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Journal of Labelled Compounds Radiopharmaceuticals
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Volume 62 | Supplement 1 | 2019 ISSN 0362-4803
The 23rd International Symposium on Radiopharmaceutical Sciences (ISRS 2019) Beijing, China, 26-31 May 2019
wileyonlinelibrary.com/journal/jlcr
wileyonlinelibrary.com/journal/jlcr
Editorial board EDITORS-IN-CHIEF R F Dannals
K M W Lawrie
Division of Nuclear Medicine The Johns Hopkins University 600 North Wolfe Street Nelson Bl-127Baltimore, Maryland 21287-0816, USA E-mail: [email protected]
Essex United Kingdom E-mail: [email protected]
LABELLED COMPOUNDS EDITOR FOR EUROPE V Derdau
RADIOPHARMA CEUTICALS EDITOR FOR ASIA, AUSTRALIA AND NEW ZEALAND M Kassiou
Medicinal Chemistry, Isotope Chemistry & Metabolite Synthesis Sanofi Industriepark Hoechst, G87665926 Frankfurt Germany E-mail: [email protected]
School of Chemistry University of Sydney NSW 2006 Sydney Australia E-mail: michael.kassiou@ sydney.edu.au
LABELLED COMPOUNDS EDITOR FOR NORTH AMERICA B D Maxwell Doylestown PA 18902, USA E-mail: [email protected]
REVIEW EDITOR F. Aigbirhio
RADIOPHARMACEUTICALS EDITOR Daniëlle Vugts VUMC, Dept Radiology & Nuclear Medicine Location Radionuclide Center 1081 HV Amsterdam, The Netherlands E-mail: [email protected]
Wolfson Brain Imaging Centre University of Cambridge Addenbrooke’s Hospital, Cambridge, CB2 2QQ, UK E-mail: [email protected]
EDITORIAL ADVISORY BOARD
C Anderson University of Pittsburgh Pittsburgh, USA G Antoni Uppsala University Uppsala, Sweden J Atzrodt R&D Sanofi Aventis Deutschland Frankfurt am Main, Germany S P Bew University of East Anglia Norwich, Norfolk, UK X Chen NBIB Bethesda, USA D Y Chi Sogang University Seoul, Korea B Cornelissen University of Oxford Oxford, UK F Dollé Service Hospitalier Frédéric Joliot Orsay, France C Elmore AstraZeneca Mölndal, Sweden
C N Filer Perkin Elmer Life Sciences Inc Boston, USA T Hartung Roche Basel, Switzerland D Hesk Merck Research Laboratories Rahway, USA J Holland University of Zurich Zurich, Switzerland J A Katzenellenbogen University of Illinois Urbana, USA W Kerr University of Strathclyde Glasgow, UK S Lapi University of Alabama Tuscaloosa, USA B Latli Boehringer Ingelheim Ridgefield, USA J Llop CICbiomaGUNE San Sebastian, Spain
W J S Lockley University of Surrey Guildford, UK N Long Imperial College London, UK D Muri Roche Basel, Switzerland D Papagiannopoulou Aristotle University Thessaloniki, Greece J Passchier Imanova London, UK T Ross Hannover Medical School Hannover, Germany H Saji Kyoto University Kyoto, Japan R Salter Johnson & Johnson Raritan, USA D Schenk Merck Rahway, USA
M Schou Astrazeneca London, UK S Stone-Elander Karolinska Pharmacy Stockholm, Sweden N Summerhill Pharmaron Cardiff, GB M L Thakur Thomas Jefferson University Philadelphia, USA N Vasdev CAMH Toronto, Canada M R Zalutsky Duke University Medical Center Durham, USA M Zanda University of Aberdeen Aberdeen, Scotland X Zhang Xiamen University Xiamen, China
wileyonlinelibrary.com/journal/jlcr
Aims and scope The Official Journal of the International Isotope Society The Journal of Labelled Compounds and Radiopharmaceuticals publishes original scientific manuscripts dealing with all aspects of research in labelled compound preparation and application. This includes areas such as analytical control, self radiolysis, quality control handling, storage, and tracer methods used in chemical, biochemical, biological, pharmacological, medical, genetic, agricultural and geochemical research. All radionuclides and enriched stable nuclides are included. The Journal of Labelled Compounds and Radiopharmaceuticals devotes particular attention to the following fields: radionuclide production; cyclotron targetry; neutron irradiation methodology; precursor preparation and production; labelling synthesis (chemical, biochemical, radiation, isotope exchange, etc); automation of nuclide production, precursor, preparation and synthesis; analysis (methods, limitations, etc. for both radioactive and stable nuclides, including new detection techniques); radiopharmaceuticals; PET chemistry; quality control (an essential requirement for valid data and especially for radiopharmaceuticals); stability and storage problems; handling of Curie and multiCurie amounts of radioactivity; etc. JLCR Award for Young Scientists: The Journal of Labelled Compounds and Radiopharmaceuticals, in cooperation with the International Isotope Society Conferences and the International Conferences on Radiopharmaceutical Sciences, sponsor every year four Awards to early excellence in radiopharmaceutical research and isotope labelling.
Copyright and copying (in any format) Copyright © 2019 John Wiley & Sons, Ltd. All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form or by any means without the prior permission in writing from the copyright holder. Authorization to copy items for internal and personal use is granted by the copyright holder for libraries and other users registered with their local Reproduction Rights Organisation (RRO), e.g. Copyright Clearance Center (CCC), 222 Rosewood Drive, Danvers, MA 01923, USA (www.copyright.com), provided the appropriate fee is paid directly to the RRO. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for republication, for creating new collective works or for resale. Permissions for such reuse can be obtained using the RightsLink “Request Permissions” link on Wiley Online Library. Special requests should be addressed to: [email protected]
Disclaimer The Publisher and Editors cannot be held responsible for errors or any consequences arising from the use of information contained in this journal; the views and opinions expressed do not necessarily ref lect those of the Publisher and Editors, neither does the publication of advertisements constitute any endorsement by the Publisher and Editors of the products advertised.
wileyonlinelibrary.com/journal/jlcr
The 23rd International Symposium on Radiopharmaceutical Sciences
Beijing, China May 26th to May 31st, 2019
Sponsored by the Society of Radiopharmaceutical Sciences
Scientific Program Committee Members
Chen, Xiaoyuan, PhD
National Institutes of Health, Bethesda, MD, USA
Chin, Frederick T., PhD
Stanford University, Stanford, CA, USA
Cutler, Cathy, PhD
Brookhaven National Laboratory, Upton, NY, USA
Gee, Antony PhD
King’s College London, London, UK
Huclier, Sandrine, PhD
Subatech Laboratory, Nantes, France
Jeong, Jae Min, PhD
Seoul National University, Seoul, South Korea
Jia, Hongmei, PhD
Beijing Normal University, Beijing, China
Kuge, Yuji, PhD
Hokkaido University, Sapporo, Japan
Kung, Hank, PhD
University of Pennsylvania, Philadelphia, PA, USA
Wang, Fan, PhD (Chair)
Peking University, Beijing, China
Yang, Zhi, PhD
Peking University, Beijing, China
Local Arrangements Committee Members Fan Wang (Chair), Professor, Peking University Zuoxiang He, Professor, Fu Wai Hospital, Chinese Academy of Medical Sciences Jian Wu, General Manager, China Isotope and Radiation CorporaƟon Minhao Xie, Professor, Jiangsu Institute of Nuclear Medicine Xianzhong Zhang, Professor, Xiamen University Zhaofei Liu, Professor, Peking University Bing Jia, Associate Professor, Peking University Jiyun Shi, Associate Professor, Institute of Biophysics, Chinese Academy of Sciences
History of ISRS: List of Venues
23rd ISRS
May 26-31, 2019 – Beijing, China
22nd ISRS
May 14-19, 2017 – Dresden, Germany
21st ISRS
May 26 – 31, 2015 – Columbia, MO, USA
20th ISRS
May 12 – 17, 2013 – Jeju Island, South Korea
19th ISRS
August 28 – September 2, 2011 – Amsterdam, Netherlands
18th ISRS
July 12- 16, 2009 – Edmonton, AB, Canada
17th ISRS
April 30 – May 4, 2007 – Aachen, Germany
16th ISRC
June 20 – 24, 2005 – Iowa City, IA, USA
15th ISRC
August 10 – 14, 2003 – Sydney, Australia
14th ISRC
June 10 – 15, 2001 – Interlaken, Switzerland
13th ISRC
June 27 – July 1, 1999 – St. Louis, MO, USA
12th ISRC
June 15 – 19, 1997 – Uppsala, Sweden
11th ISRC
August 13 – 17, 1995 – Vancouver, BC, Canada
10th ISRC
October 25 – 28, 1993 – Kyoto, Japan
9th ISRS
April 6 – 10, 1992 – Paris, France
8th ISRS
June 24 – 29, 1990 – Princeton, NJ, USA
7th ISRS
July 4 – 8, 1988 – Groningen, Netherlands
6th ISRS
June 29 – July 3, 1986 – Boston, MA, USA
5th ISRC
July 9 – 13, 1984 – Tokyo, Japan
4th ISRC
August 23 – 27, 1982 – Jülich, Germany
3rd ISRC
June 16 – 20, 1980 – St. Louis, MO, USA
2nd ISRC
July 3 – 7, 1978 – Oxford, Great Britain
1st ISRC
September 21– 24, 1976 – Brookhaven, NY, USA
Abstract Reviewers Adam, Michael, Canada Alberto, Roger, Switzerland Ametamey, Simon, Switzerland Anderson, Carolyn, United States Antoni, Gunnar, Sweden Arstad, Erik, United Kingdom Avila-Rodriguez, Miguel, Mexico Barkhausen, Christoph, Germany Barre, Louisa, France Berroteran-Infante, Neydher, Austria Bhalla, Rajiv, Australia Bilewicz, Aleksander, Poland Blower, Phil, United Kingdom Bongarzone, Salvatore, United Kingdom Brechbiel, Martin, United States Brust, Peter, Germany Chan, James, Australia Chen, Xiaoyuan, United States Cheng, Zhen, United States Chi, Dae Yoon, Korea, Republic of Choe, Yearn Seong, Korea, Republic of Chun, Joong-Hyun, Korea, Republic of Clark, John, United Kingdom Coenen, Heinz, Germany Cui, Mengchao, China Cutler, Cathy, United States DeGrado, Timothy, United States Deri, Melissa, United States Dolleˊ, Freˊdeˊric, France Donnelly, Paul, Australia Eckelman, William, United States Ekoume, Fany, Cameroon Elsinga, Philip, Netherlands Francesconi, Lynn, United States Fuchigami, Takeshi, Japan Gagnon, Katie, Sweden Gee, Antony, United Kingdom Gott, Matthew, United States Halldin, Christer, Sweden Haskali, Mohammad, Australia Herth, Matthias, Sweden Hoepping, Alexander, Germany Holger, Stephan, Germany Horti, Andrew, United States Janssen, Bieneke, United States Jensen, Svend, Denmark Jeong, Jae Min, Korea, Republic of Jia, Hongmei, China Jia, Bing, China Jin, Hongjun, China Jurisson, Silvia, United States Kassiou, Michael, Australia Kilbourn, Michael, United States Kim, Hee-Kwon, Korea, Republic of
Kim, Dong Wook, Korea, Republic of Kirjavainen, Anna, Finland Kiyono, Yasushi, Japan Kniess, Torsten, Germany Kopka, Klaus, Germany Krasikova, Raisa, Russian Federation Krohn, Kenneth, United States Kubeil, Manja, Germany Kuge, Yuji, Japan Kuhnast, Bertrand, France Lapi, Suzanne, United States Larsen, Peter, Denmark Laube, Markus, Germany Lebeda, Ondrej, Czech Republic Lee, Kyo Chul, Korea, Republic of Lee, Byung Chul, Korea, Republic of Lee, Yun-Sang, Korea, Republic of Lever, Susan, United States Lewis, Jason, United States Lewis, Michael, United States Li, Zijing, China Liang, Steven, United States Link, Jeanne, United States Liu, Zhaofei, China Liu, Zhibo, China Loeser, Reik, Germany Ma, Michelle, United Kingdom Mach, Robert, United States Maina-Nock, Theodosia, Greece Mamat, Constan n, Germany Mathis, Chester, United States Meyer, Geerd, Germany Middel, Oskar, Norway Mikolajczak, Renata, Poland Mindt, Thomas, Austria Moldes-Amaya, Angel, Norway Mu, Linjing, Switzerland Mukherjee, Jogeshwar, United States Nagren, Kjell, Denmark Neels, Oliver, Germany Neumaier, Bernd, Germany Nickles, Robert, United States Ogawa, Kazuma, Japan Ogawa, Mikako, Japan Orvig, Chris, Canada Pandey, Mukesh, United States Papagiannopoulou, Dionysia, Greece Pascali, Claudio, Italy Pascali, Giancarlo, Australia Pichler, Verena, Austria Piel, Markus, Germany Pietzsch, Hans-Jürgen, Germany Pietzsch, Jens, Germany Pike, Victor, United States
Pillarsetty, Naga Vara Kishore, United States Poot, Alex, Netherlands Qaim, Syed, Germany Quinn, Thomas, United States Radchenko, Valery, Canada Ramogida, Caterina, Canada Reichert, David, United States Riss, Patrick, Norway Ross, Tobias, Germany Rotsch, David, United States Rotstein, Benjamin, Canada Rubow, Sietske, South Africa Samnick, Samuel, Germany Schultz, Michael, United States Scott, Peter, United States Signore, Alberto, Italy Spreckelmeyer, Sarah, Germany Stehouwer, Jeff, United States Steinbach, Jörg, Germany Toyohara, Jun, Japan Ueda, Masashi, Japan van Dam, R. Michael, United States van der Wildt, Berend, United States VanBrocklin, Henry, United States Verbruggen, Alfons, Belgium Vraka, Chrysoula, Austria Vugts, Danielle, Netherlands Wadsak, Wolfgang, Austria Wängler, Björn, Germany Wang, Mingwei, China Wang, Fan, China Wester, Hans-Juergen, Germany Windhorst, Albert, Netherlands Wuest, Frank, Canada Xin, Yangchun, United States Yang, Zhi, China Yang, Xing, China Yordanov, Alexander, United States Zhang, Ming-Rong, Japan Zhang, Jinming, China Zhang, Xianzhong, China Zhang, Junbo, China Zhu, Hua, China Baranski, Ann-Christin, Germany Decristoforo, Clemens, Austria Bolzati, Cristina, Italy Gillings, Nic, Denmark Solin, Olof, Finland Garg, Pradeep, United States Huclier, Sandrine, France Wichmann, Christian, Australia
Contents Orals
S6: Oral
23rd International Symposium on Radiopharmaceutical Sciences
KEYNOTE LECTURE 1 O-01
Pioneers require a spirit of determination and challenge: Milestones of PET radiopharmaceutical development T. Ido Neuroscience Research Institute, Gachon University, South Korea
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KEYNOTE LECTURE 2 O-02
Clinical translation of molecular imaging in nuclear medicine: PUMCH experience S 14 F. Li Peking Union Medical College Hospital, China; Beijing Key Laboratory of Molecular Imaging Diagnosis and Treatment of Nuclear Medicine, China; China Association of Nuclear Medicine Equipment, China; Chinese Journal of Nuclear Medicine and Molecular Imaging, China
RADIOLABELED COMPOUNDS - ONCOLOGY (IMAGING) SESSION 1 O-03
O-04
O-05
O-06
Bispecific anti-GRPR/PSMA heterodimer for PET and SPECT imaging diagnostic of prostate cancer A. Orlova1, B. Mitran1, Z. Varasteh1, A. Abouzayed1, S. Rinne1, M. Larhed2, V. Tolmachev1, U. Rosenström1 1Uppsala University, Sweden; 2Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden Pretargeted tumor imaging with 64Cu-labeled ultrastable cross-bridged macrocyclic complex A. Bhise1, S. Sarkar2, P. Huynh2, W. Lee2, J. Y. Kim3, K. C. Lee4, J. Yoo1 1Kyungpook National University, Republic of Korea; 2Department of Molecular Medicine, Kyungpook National University, Republic of Korea; 3KIRAMS(Korea Institue of Radiological and Medical Sciences), Republic of Korea; 4KIRAMS, Republic of Korea Targeting CD206+ tumor-associated macrophages using a finely tuned albumin nano-platform for earlier detection of breast cancer metastases Ji Yong Park1, H. Chung2, K. Kim1, M. Suh1, S. H. Seok2, Y. Lee3 1Seoul National University, College of Medicine, Republic of Korea; 2Seoul National University, Republic of Korea; 3Seoul National University Hospital, Republic of Korea Improving pharmacokinetics of 99mTc-ref with PEG linkers for HER2-targeted SPECT imaging of breast cancer S. Du1, H. Gao1, C. Luo1, G. Yang1, Q. Luo2, B. Jia1, J. Shi3, F. Wang1,2 1Peking University, China; 2Institute of Biophysics, CAS, China; 3Institute of Biophysics, CAS, China
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RADIOCHEMISTRY - 18F SESSION 1 O-07
O-08
O-09
O-10
O-11
O-12
Generation of 18F-metal fluorides from [18F]HF generated by acidic QMA elution and application towards 18F-fluorination/ring-opening of complex epoxides S. Verhoog1, A. Brooks2, W. Winton2, A. Mossine2, M. Sanford2, P. Scott3 1Merck & Co Inc, USA; 2University of Michigan, USA; 3The University of Michigan, USA Pretargeted PET imaging using a dual click 18F-labeling strategy J. Steen1, C. Denk2, J. Jørgensen3, K. Nørregard3, R. Rossin5, M. Wilkovitsch2, D. Svatunek2, P. Edem6, C. Kuntner4, T. Wanek4, M. Robillard5, J. Kristensen6, A. Kjær3, H. Mikula2, M. Herth7 1Department of Drug Design and Pharmacology, University of Copenhagen, Denmark; 2Institute of Applied Synthetic Chemistry, Technische Universität Wien (TU Wien), Austria; 3Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 4Health and Environment Department, Biomedical Systems, Austrian Institute of Technology (AIT), Austria; 5Tagworks Pharmaceuticals, Netherlands; 6Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 7Univesity of Copenhagen, Sweden Development of high affinity 18F-labelled radiotracers for PET imaging of the adenosine A2A receptor T. H. Lai1, S. Schroeder1, F. Ludwig2, S. Fischer3, R. Moldovan4, M. Scheunemann1, S. Dukic-Stefanovic1, W. Deuther-Conrad1, J. Steinbach1, P. Brust1 1Helmholtz-Zentrum Dresden-Rossendorf, Germany; 2Department of Neuroradiopharmaceuticals, Institute for Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Germany; 3HZDR, FS Leipzig, Germany; 4Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden Rossendorf, Germany Preparation of [18F]fluoroalkenyliodonium salts and their application for radiolabeling by cross-coupling reactions S. Humpert1, M. Holschbach2, D. Bier3, B. Zlatopolskiy4, B. Neumaier1 1Forschungszentrum Jülich GmbH, Germany; 2Foschungszentrum Jülich GmbH, Germany; 3Forschungszentrum Juelich, Germany; 4Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany High molar activity [18F]trifluoromethane for PET tracer synthesis A. Pees1, M. Vosjan2, V. Tadino3, J. Y. Chai4, H. Cha4, D. Y. Chi4, A. Windhorst5, D. Vugts1 1Amsterdam UMC, VU University, Netherlands; 2BV Cyclotron VU, Netherlands; 3ORA Neptis, Belgium; 4Department of Chemistry, Sogang University, Republic of Korea; 5VU University Medical Center, Netherlands Synthesis and evaluation of [18F]canagliflozin for imaging SGLT-2-transporters in diabetic patients K. Attia, T. Visser, J. Steven, R. Slart, I. Antunes, S. van der Hoek, P. Elsinga, H. Heerspink University Medical Center Groningen, Netherlands
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J Label Compd Radiopharm 2019: 62 (Suppl. 1): S5–S122
23rd International Symposium on Radiopharmaceutical Sciences
Oral: S7
MULTIMODALITY IMAGING PROBES/NANOPARTICLES O-13
O-14
O-15
O-16
Magnetic nanotheranostics enhances Cherenkov radiation–induced photodynamic therapy D. Ni1, D. Jiang1, W. Wei2, L. Kang3, J. Engle4, W. Cai1 1University of Wisconsin-Madison, USA; 2Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 3Peking University First Hospital, China; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA Bimodal PSMA ligands for intra-operative tumor detection and targeted photodynamic therapy of PSMA-expressing tumors Y. Derks1, H. Amatdjais2, J. Malekzad2, G. Franssen1, A. Kip1, D. Lowik2, O. Boerman1, M. Rijpkema1, P. Laverman1, S. Lutje1, S. Heskamp1 1Radboud University Medical Center, Netherlands; 2Radboud University, Netherlands Evaluation of N-alkylaminoferrocenes for in-vivo imaging of reactive oxygen species activity using PET and optical imaging J. Toms1, S. Maschauer1, S. Daum2, V. Reshetnikov2, A. Mokhir2, O. Prante1 1Department of Nuclear Medicine, Molecular Imaging and Radiochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Germany; 2Department of Chemistry and Pharmacy, Organic Chemistry II, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Germany A Cell surface thiol targeting dual PET and fluorescent labelling reagent for multi-scale cell tracking T. Pham1, R. Yan, J. Maher King’s College London, UK
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RADIOCHEMISTRY - RADIOMETALS O-17
O-18
O-19
O-20
O-21
O-22
Towards cancer theranostics: 68Ga-, 44gSc-, 177Lu-, and 225Ac-labeled bombesin derivatives S. Ferguson1, M. Wuest1, C. Bergman1, N. Thiele2, S. Richter1, H. Jans1, V. Radchenko3, P. Causey4, R. Perron4, P. Schaffer3, J. Wilson2, T. Riauka1, F. Wuest1 1University of Alberta, Canada; 2Cornell University, USA; 3TRIUMF, Canada; 4Canadian Nuclear Laboratories (CNL), Canada Synthesis and comparison of novel fusarinine C-based chelators for 89Zr-labeling C. Zhai1, S. He2, X. Chen3, J. Lu3, C. Rangger4, D. Summer, H. Haas5, J. Foster6, J. Sosabowski7, C. Decristoforo8 1Southern Medical University, China; 2Department of Nuclear Medicine, Guangdong General Hospital, China; 3School of Forensic Medicine, Southern Medical University, China; 4Department of Nuclear Medicine, Medical University Innsbruck, Austria; 5Division of Molecular Biology, Biocenter, Medical University Innsbruck, Austria; 6Centre for Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, UK; 7Centre for Molecular Oncology and Imaging, UK; 8Medical University Innsbruck, Austria New bifunctional chelators for theranostic applications L. L. Li1, M. Jaraquemada-Pelaez2, N. Sarden2, H. Kuo3, E. A. Sarduy4, A. Robertson5, T. Kostelnik2, U. Jermilova2, E. Ehlerding4, H. Merkens6, K. Gitschtaler6, V. Radchenko7, K. Lin3, F. Benard3, J. Engle4, P. Schaffer7, C. Orvig1 1The University of British Columbia, Canada; 2Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, BC, Canada; 3BC Cancer Research Centre, Canada; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; 5Life Sciences Division, TRIUMF, Vancouver, BC, Canada; 6Department of Molecular Oncology, BC Cancer Agency, Vancouver, BC, Canada; 7TRIUMF, Canada Cooperative capture synthesis for the development of novel supramolecular radiotracers F. d’Orchymont, J. Holland Department of Chemistry, University of Zurich, Switzerland In vivo stable bisarylmercury bispidine as a tool for Hg-197(m) applications I. M. Gilpin1, M. Walther2, J. Pietzsch3, H. Pietzsch2 1HZDR, Germany; 2Helmholtz-Zentrum Dresden-Rossendorf, Germany; 3Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Germany Positron emission tomography imaging of adeno-associated virus serotype 9-tetracystein (AAV9-TC) labeled with a multichelator J. W. Seo1, L. Mahakian2, E. Ingham2, S. Tumbale3, S. Shams2, E. Silva2, K. Ferrara2 1Stanford University, USA; 2Biomedical Engineering, UC Davis, USA; 3Radiology, Stanford, USA
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KEYNOTE LECTURE 3 O-23
Catalyzing the development and use of radiopharmaceuticals with total-body PET S. Cherry UC Davis
S 41
WILEY AWARD SESSION O-24
O-25
11C-Trifluoromethylation of primary aromatic amines with [11C]CuCF via diazonium salts generated in situ 3 N. Young1, C. Taddei, V. Pike National Institute of Mental Health, USA A long-acting radiolabeled RGD analogue 177Lu-AB-3PRGD2 for targeted radiotherapy of tumor H. Gao1, G. Yang1, C. Luo1, B. Jia1, J. Shi2, F. Wang1 1Peking University, China; 2Institute of Biophysics, CAS, China
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S5–S122
S 42
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S8: Oral
O-26
O-27
23rd International Symposium on Radiopharmaceutical Sciences
Development of a radiation detector for miniaturized analysis of radiopharmaceutical samples via microchip electrophoresis J. Jones1, N. Ha2, R. M. van Dam3 1UCLA, USA; 2Lawrence Berkeley National Laboratory, USA; 3Crump Institute for Molecular Imaging, UCLA, USA Develop a peptide-based PET radiotracer for imaging PD-L1 expression in cancer K. Hu1, M. Zhang2, M. Hanyu3, L. Xie3, Y. Zhang4 1National Institute of Radiological Sciences, Japan; 2Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Japan; 4Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
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RADIOCHEMISTRY - 11C AND OTHER POSITRON EMITTERS O-28
O-29
O-30
O-31
O-32
O-33
In-loop carbonylation-a novel and simplified method for carbon-11 labeling of drugs and radioligands M. Ferrat2, Y. E. Khoury2, K. Dahl1, C. Halldin2, M. Schou3 1CAMH and University of Toronto, Canada; 2Karolinska Institutet, Sweden; 3AstraZeneca PET Centre at Karolinska Institutet, Sweden Palladium/copper-mediated rapid 11C-cyanation of (hetero)arylstannanes Z. Zhang1, T. Niwa, Y. Watanabe, T. Hosoya RIKEN Center for Biosystems Dynamics Research, Japan Rapid, one-pot radiosynthesis of [carbonyl-11C]formamides from primary amines and [11C]CO2 F. Luzi1, S. Bongarzone, A. Gee King’s College London, UK Radiosynthesis of carbon-11 labeled acylsulfonamides using [11C]CO carbonylation chemistry B. van der Wildt, B. Shen, F. Chin Stanford University, USA Synthesis of radiolabeled [11C]formamides: A new carbon-11 labeled building block to access novel PET tracers C. Bonnemaire1, J. Collet2, E. Ruijter3, R. Orru3, A. Windhorst4, D. Vugts5 1UMC Amsterdam, Netherlands; 2Department of Radiology and Nuclear Medicine, Netherlands; 3Vrije Universiteit Amsterdam, Netherlands; 4VU University Medical Center, Netherlands; 5Amsterdam UMC, VU University, Netherlands Rapid and efficient BEMP-mediated synthesis of 11C-labelled benzimidazolones using [11C]carbon dioxide K. Horkka1, K. Dahl2, C. Halldin1, M. Schou3 1Karolinska Institutet, Sweden; 2CAMH and University of Toronto, Canada; 3AstraZeneca PET Centre, Karolinska Institutet, Sweden
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RADIOLABELED COMPOUNDS - OTHER MEDICAL DISCIPLINES AND RADIOPHARMACOLOGY AND CARDIOLOGY O-34
O-35
O-36
O-37
[11C]Metoclopramide as a PET tracer to visualize ABCB1 induction at the mouse blood-brain-barrier S. Mairinger1, V. Zoufal2, T. Wanek3, M. Brackhan4, J. Stanek2, T. Filip2, M. Sauberer2, N. Tournier5, J. Pahnke4, O. Langer2 1Preclinical Molecular Imaging, AIT Austrian Institute of Technology GmbH, Austria; 2AIT Austrian Institute of Technology GmbH, Austria; 3Health and Environment Department, Biomedical Systems, Austrian Institute of Technology (AIT), Austria; 4Department of Neuro-/Pathology, University of Oslo (UiO) and Oslo University Hospital (OUS), Norway; 5CEA, France A novel high-throughput cassette microdosing approach to screen PET imaging agents M. Sun1, H. Xiao2, H. Hong1, A. Zhang3, Y. Zhang1, Y. Liu2, L. Zhu4, H. Kung5, J. Qiao1 1College of Chemistry, Beijing Normal University, China; 2Beijing Institute of Brain Disorders, Capital Medical University, China; 3Collage of Chemistry, Beijing Normal University, China; 4Beijing Normal University, China; 5University of Pennsylvania, USA Synthesis and in vivo evaluation of a novel 18F-labelled PET tracer 18F-BBR for myocardial perfusion imaging in mice X. Wu1 , M. Liang2, R. Wang2, H. Cai2, Y. Chen2, C. Fan1 1Sichuan University, China; 2The Affiliated Hospital of Southwest Medical University, China Exclusive kidney accumulation of DNA origami nanostructures protects kidneys from acute injury D. Jiang1, D. Ni1, W. Wei2, L. Kang3, J. Engle4, W. Cai1 1University of Wisconsin-Madison, USA; 2Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 3Peking University First Hospital, China; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
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RADIOLABELED COMPOUNDS - ONCOLOGY (IMAGING) SESSION 2 O-38
Development of the first 18F-labeled MCT1/MCT4 lactate transport inhibitor: Radiosynthesis and preliminary in vivo evaluation in mice M. Sadeghzadeh1, R. Moldovan2, B. Wenzel1, M. Kranz1, W. Deuther-Conrad1, M. Toussaint1, S. Fischer3, F. Ludwig4, R. Teodoro2, S. Jonnalagadda5, S. Jonnalagadda5, L. Drewes5, P. Brust1 1Helmholtz-Zentrum Dresden-Rossendorf, Germany; 2Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden Rossendorf, Germany; 3HZDR, FS Leipzig, Germany; 4Department of Neuroradiopharmaceuticals, Institute for Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Germany; 5University of Minnesota Duluth, USA
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Preclinical evaluation of 99mTc-labeled anti-EpCAM nanobody conjugates for imaging EpCAM receptor expression by immuno-SPECT T. Liu1, Y. Wu1, L. Shi2, Y. Wang3, H. Gao4, B. Hu4, X. Zhang2, H. Zhao1, Y. Wan5, B. Jia4, F. Wang4 1Medical Isotopes Research Center and Department of Radiation Medicine, Peking University, China; 2Medical Isotopes Research Center and Department of Radiation Medicine, China; 3Medical Isotopes Research Center, Peking University, China; 4Peking University, China; 5CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, China PET imaging of human melanoma using a novel 18F-labeled dual AmBF3 derivative of alpha-melanocyte stimulating hormone C. Zhang1, Z. Zhang1, K. Lin1, H. Merkens2, J. Zeisler1, N. Colpo1, D. Perrin3, F. Benard1 1BC Cancer Research Centre, Canada; 2Department of Molecular Oncology, BC Cancer Agency, Vancouver, BC, Canada; 3Department of Chemistry, University of British Columbia, Canada Imaging of in vivo tumor senescence with a novel beta-galactosidase specific PET tracer J. Cotton1, B. Zhou1, J. Schwenck2, K. Wolter3, A. Kuehn4, K. Fuchs4, G. Reischl5, A. Maurer1, C. la Fougère2, L. Zender6, M. Krueger1, B. Pichler4 1Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University of Tübingen, Germany; 2Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard Karls University of Tübingen, Germany; 3Department of Physiology I, Institute of Physiology, Eberhard Karls University of Tübingen, Germany; 4Werner Siemens Imaging Center, Germany; 5University Hospital Tübingen, Germany; 6Department of Internal Medicine VIII, University Hospital Tübingen, Germany The in vivo and in vitro validation of two activin-receptor like kinase 5 targeting PET tracers L. Rotteveel1, A. Poot2, P. Dijke3, H. J. Bogaard4, A. Lammertsma4, A. Windhorst5 1Radiology and Nuclear Medicine, Radionuclide Center, Amsterdam UMC, VU University, Amsterdam, The Netherlands; 2Amsterdam UMC, VU University, Netherlands; 3Department of Molecular Cell Biology, Leiden University Medical Centre, Netherlands; 4Amsterdam UMC, VUmc, Netherlands; 5VU University Medical Center, Netherlands Molecular imaging of autotaxin: Targeting the crossroad of inflammation and cancer M. Litchfield1, M. Wuest1, E. Briard2, Y. Auberson3, T. McMullen1, D. Brindley1, F. Wuest1 1University of Alberta, Canada; 2Novartis Pharma AG, Switzerland; 3Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Switzerland
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Engineered antibodies—New possibilities for brain PET S. Syvanen Uppsala University, Sweden
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Toward Auger radiotherapy with rhodium-103m: Bifunctional 16aneS4 chelator synthesis and development of a rhodium-103m generator C. Magnus1, G. Severin2, F. Zhuravlev3, U. Köster4, J. Fonslet3, M. Jensen3, A. Jensen1 1DTU Nutech, Technical University of Denmark (DTU), Denmark; 2Technical University of Denmark, Denmark; 3Center for Nuclear Technologies, Technical University of Denmark, Denmark; 4Institut Laue-Langevin, France Synthesis of precursors for 211At-labelling of anti-PSMA HuJ591 mAb and stability comparison after in vitro cellular internalization A. Roumesy1, S. Gouard1, L. Navarro1, F. Lelan1, F. Haddad2, F. Guérard3, A. Faivre-Chauvet, M. Chérel4, J. Gestin4 1CRCINA, France; 2GIP ARRONAX, France; 3CRCINA, Inserm, CNRS, Nuclear Oncology Group, France; 4CRCINA, Inserm, CNRS, France Radiosynthesis of a novel 77Br-labeled PARP-1 inhibitor through Cu-mediated aryl boronic ester bromination P. Ellison1, J. Burkemper2, A. Olson3, S. Hoffman1, S. Reilly4, M. Makvandi4, R. Mach5, T. Barnhart1, S. Lapi6, J. Engle7 1University of Wisconsin, USA; 2Department of Radiology, University of Alabama, Birmingham School of Medicine, USA; 3Department of Medical Physics, University of Wisconsin, USA; 4Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, University of Pennsylvania, Perelman School of Medicine, USA; 5University of Pennsylvania, USA; 6University of Alabama at Birmingham, USA; 7Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA Large-scale production and isolation of theranostic radionuclides 76Br and 77Br P. Ellison1, A. Olson2, S. Hoffman1, T. Barnhart1, R. Nickles3, J. Engle4 1University of Wisconsin, USA; 2Department of Medical Physics, University of Wisconsin, USA; 3University of Wisconsin Medical Physics, USA; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
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Neuroinflammation imaging with the P2X7R PET tracer [11C]SMW139 in the experimental autoimmune encephalomyelitis (EAE) model W. Beaino1 , B. Janssen2, E. Kooijman3, R. Vos3, R. Schuit3, M. Kassiou4, D. Vugts3, H. de Vries3, A. Windhorst5 1Radiology and Nuclear Medicine, Radionuclide Center, Amsterdam UMC, VU University, Amsterdam, The Netherlands; 2University of Pennsylvania, USA; 3Amsterdam UMC, VU University, Netherlands; 4The University of Sydney, Australia; 5VU University Medical Center, Netherlands
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Fluorinated benzimidazole sulfones as candidate radioligands for CB2 PET-imaging A. Kallinen1, R. Boyd2, S. Lane1, R. Bhalla2, K. Mardon2, D. Stimson3, G. Cowin2, F. Nasrallah2, E. Werry1, M. Connor2, M. Kassiou1 1The University of Sydney, Australia; 2University of Queensland, Australia; 3Royal Prince Alfred Hospital, Australia Synthesis and evaluation in rats of [11C]NR2B-Me as a PET radioligand for NR2B subunits in NMDA receptors L. Cai1, J. Liow2, C. Morse2, R. Davies4, M. Frankland3, S. Zoghbi3, R. Innis1, V. Pike1 National Institute of Mental Health, USA; 2NIH, USA; 3NIMH, USA; 4Oberlin College, USA Evaluation of a novel iodine-125 ligand for efficient α-synuclein compound screening B. Janssen1, Z. Lengyel2, C. Hsieh1, J. Ferrie1, A. Riad1, K. Xu1, C. Weng3, E. J. Petersson1, R. Mach1 1University of Pennsylvania, USA; 2University of Pennsylvania School of Medicine, USA; 3Department of Radiology, University of Pennsylvania, USA Synthesis of [18F]fluorotetrazines and coupling to trans-cyclooctene functionalized antibodies for amyloid-beta PET J. Rokka1, X. Fang2, G. Hultqvist1, R. Faresjö1, D. Olberg3, G. Antoni4, L. Lannfelt5, D. Sehlin5, S. Syvanen5, J. Eriksson5 1Uppsala University, Sweden; 2Yale University, USA; 3Norsk medisinsk syklotronsenter AS/University of Oslo, Norway; 4Uppsala University Hospital, Sweden; 5Uppsala University Hospital and Department of Medicinal Chemistry, Uppsala University, Sweden Automated routine implementation of [11C]ITDM for a longitudinal evaluation of mGluR1 availability in the Q175DN mouse model for Huntington’s disease Špela Korat1, D. Bertoglio1, K. Cybulska1, J. Verhaeghe1, A. Miranda1, L. Mrzljak2, J. Bard2, C. Dominguez2, L. Liu2, I. Munoz-Sanjuan2, S. Stroobants3, L. Wyffels1, S. Staelens1 1Molecular Imaging Center Antwerp, University of Antwerp, Belgium; 2CHDI Foundation, USA; 1Antwerp University Hospital, Belgium
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Development of radiopharmaceutical; from bench to FDA approved clinical application H. F. Kung Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA; Five Eleven Pharma Inc, Philadelphia, PA, USA
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High-throughput radio-TLC using Cerenkov luminescence imaging J. Wang1, A. Rios1, K. Lisova1, R. Slavik2, A. F. Chatziioannou2, R. M. van Dam2 1UCLA, USA; 2Crump Institute for Molecular Imaging, UCLA, USA Rapid, inexpensive, and high-yielding radiosynthesis of 68Ga-PSMA using a versatile microfluidic device for prostate cancer PET imaging X. Zhang1, M. Nickels, F. Liu, L. Bellan, H. Manning Vanderbilt University, USA Automated radiosynthesis of [18F]atorvastatin via Ru-mediated 18F-deoxyfluorination: A prospective PET imaging tool for the assessment of statin related mechanisms of action G. Clemente1, J. Rickmeier2, T. Zarganes-Tzitzikas3, I. Antunes4, R. Slart3, A. Dömling3, T. Ritter2, P. Elsinga1 1University Medical Center Groningen, Netherlands; 2Max-Planck-Institut für Kohlenforschung, Germany; 3Department of Drug Design, University of Groningen, Netherlands; 4UMCG, Netherlands Online positron detector for LC/MS/MS A. Kirjavainen1, S. Lahdenpohja1, S. Forsback2, O. Solin2 1Turku PET Center, University of Turku, Finland; 2University of Turku, Finland
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Radiosynthetic optimization of the SV2A radiotracer 18F-SDM-8: A search for the best precursor X. Wu1, S. Li2, M. Zheng3, Y. Huang4 1Sichuan University, China; 2Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA; 3Yale University School of Medicine, USA; 4PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA Discovery and first-in-human evaluation of M4 PAM PET tracer [11C]MK-6884 W. Li1 , Y. Wang, Z. Zeng1, T. Lohith1, L. Tong1, R. Mazzola1, K. Riffel2, P. Miller1, M. Purcell1, M. Holahan1, H. Haley1, L. Gantert1, J. Morrow1, T. Bueters1, J. Uslaner1, J. de Hoon3, G. Bormans4, M. Koole4, K. Laere4, K. Serdons4, R. Declercq5, I. Lepeleire5, M. Rudd1, D. Tellers1, A. Basile1, E. Hostetler1 1Merck Research Laboratories, USA; 2Merck & Co, Inc, USA; 3University Hospital Leuven, Belgium; 4KU Leuven, Belgium; 5Merck Sharp & Dohme (Europe) Inc, Belgium An 18F-labeled radiotracer for PET imaging of 11β-HSD1: From chemistry development to clinical study S. Li1, S. Bhatt1, D. Matuskey2, D. Holden1, W. Zhang3, Z. Cai2, N. Nabulsi4, Y. Ye1, H. Gao2, M. Kapinos2, R. Carson1, S. McKee5, K. Cosgrove5, A. Hillmer1, Y. Huang2 1Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA; 2PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA; 3Department of Nuclear Medicine, West China Hospital, Sichuan University, China; 4Yale PET Center, USA; 5Department of Psychiatry, Yale University, USA
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Structure-activity relationship studies of pyridine-based ligands and identification of a fluorinated derivative for the PET imaging of cannabinoid type 2 receptors A. Haider4, J. Kretz, L. Gobbi1, U. Grether2, C. Ullmer2, M. Honer2, I. Knuesel2, A. M. Herde4, M. Weber2, A. Brink2, C. Keller3, R. Schibli3, L. Mu3, S. Ametamey4 1F. Hoffmann - La Roche, Switzerland; 2Hoffmann-La Roche Ltd, Switzerland; 3ETH Zurich, Switzerland; 4Radiopharmacy, ETH Zurich, Switzerland; 5Kantonsspital St. Galen, Switzerland Synthesis and evaluation of 18F-labeled benzimidazopyridine derivatives as novel PET tracers for tau imaging H. Watanabe1, S. Kaide1, Y. Tarumizu1, Y. Shimizu2, S. Iikuni3, M. Ono3 1Graduate School of Pharmaceutical Sciences, Kyoto University, Japan; 2Graduate School of Medicine, Kyoto University, Kyoto, Japan; 3Kyoto University, Japan Development of a carbon-11 PET pro-radiotracer for imaging the astroglial excitatory amino acid transporter 2 I. Fontana2, E. Zimmer1, D. Souza1, S. Bongarzone2, A. Gee2 1Universidade Federal do Rio Grande do Sul, Brazil; 2King’s College London, United Kingdom
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Comparison of Al18F and 68Ga-labeled NOTA-PEG4-LLP2A for PET imaging of very late antigen-4 in melanoma Y. Gai1, L. Yuan, H. Li, X. Lan Department of Nuclear Medicine, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, China 18F-labelled click based PSMA-tracer for prostate cancer imaging V. Bohmer1, D. van der Born2, W. Szymanski3, I. Antunes3, M. Klopstra4, D. Samplonius1, J. Sijbesma1, W. Helfrich1, T. Visser4, B. Feringa1, P. Elsinga1 1University Medical Center Groningen, Netherlands; 2FutureChemistry Holding B.V., Netherlands; 3UMCG, Netherlands; 4Syncom, Netherlands Preclinical evaluation of [18F]DiFA, a novel hypoxia PET probe, in a rat intracranial glioma model H. Yasui1, K. Higashikawa1, Y. Shibata2, H. Matsumoto3, T. Shiga4, N. Tamaki5, Y. Kuge1 1Hokkaido University, Japan; 2Graduate School of Biomedical Science and Engineering, Hokkaido University, Japan; 3Nihon Medi-Physics Co, Ltd, Japan; 4Graduate School of Medicine, Hokkaido University, Japan; 5Department of Radiology, Kyoto Prefectural University of Medicine, Japan Dynamic PET/CT imaging of 18F-(2S, 4R)4-fluoroglutamine in breast cancer patients X. Xu1,2,3,4,5, H. Zhu1,2,3,4,5, Z. Yang1,2,3,4,5 Hokkaido University, Japan; 2Graduate School of Biomedical Science and Engineering, Hokkaido University, Japan; 3Nihon Medi-Physics Co, Ltd, Japan; 4Graduate School of Medicine, Hokkaido University, Japan; 5Department of Radiology, Kyoto Prefectural University of Medicine, Japan
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Dual radionuclide theranostic pretargeting O. Keinanen1, R. Membreno, K. Fung, B. Zeglis Hunter College, USA [68Ga]/[177Lu]P17-087: A potential theranostic agent targeting PSMA expressing tumor H. Kung1, S. R. Choi2, Z. Zha1, K. Ploessl1, D. Alexoff3 1University of Pennsylvania, USA; 2Five Eleven Pharma, USA; 3Five Eleven Pharma Inc, USA Selection of the optimal macrocyclic chelators for labelling with 111In and 68Ga improves contrast of HER2 imaging using engineered scaffold protein ADAPT6 V. Tolmachev1, S. Lindbo2, M. Altai1, E. von Witting2, A. Vorobyeva1, M. Oroujeni1, B. Mitran1, A. Orlova1, J. Garousi1, S. Hober2 1Uppsala University, Sweden; 2KTH, Royal Institute of Technology, Sweden A Metabolically stable boron-derived tyrosine serves as a theranostic agent for positron emission tomography guided boron neutron capture therapy J. Li1, Y. Shi, Z. Zhang2, T. Liu2, X. Chen3, Z. Liu1 1Peking University, China; 2Beijing Capture Tech (BCTC), China; 3NIBIB/CC/NIH, USA Barium ferrite magnetic nanoparticles labeled with 223Ra: A new potential magnetic radiobioconjugate for targeted alpha therapy A. Bilewicz1, E. Cedrowska1, W. Gawęda1, F. Bruchertseifer, A. Morgenstern2 1Instutute of Nuclear Chemistry and Technology, Poland; 2Institute for Transuranium Elements, Germany Photodynamic therapy with a CD276-targeted agent for enhancing tumor anti-PD-1/PD-L1 immune checkpoint inhibition B. Rui1 , Y. Wang2, L. Jianhao1, Z. Liu3, F. Wang3 1Medical Isotopes Research Center and Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, China; 2Medical Isotopes Research Center, Peking University, China; 3Peking University, China
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Synthesis of photoactivatable HBED-CC and immunoPET of the hepatocyte growth factor receptor c-MET using photoradiolabelled [68Ga]GaHBED-CC-MetMAb R. Fay1, M. Gut2, J. Holland2 1University of Zurich, Switzerland; 2Department of Chemistry, University of Zürich, Switzerland
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Preclinical evaluation of a 68Ga-labeled bombesin antagonist comprising the bifunctional chelator NODIA-Me A. Schmidtke, M. Gut1, R. Fay2, J. Holland1, S. Ezziddin3, M. Bartholomae3 1Department of Chemistry, University of Zürich, Switzerland; 2University of Zürich, Switzerland; 3Medical Center, Saarland University, Germany In-vivo PET imaging of αvβ8-integrin J. Notni, A. Wurzer, F. Reichart, O. Maltsev, K. Steiger, R. Beck, H. Wester, M. Schwaiger, H. Kessler Technical University Munich, Germany Trans-cyclooctene-functionalized PeptoBrushes with improved reaction kinetics of the tetrazine ligation for pretargeted nuclear imaging J. Steen1, K. Nørregard2, K. Johann3, J. Jørgensen2, D. Svatunek4, A. Birke3, P. Edem7, R. Rossin6, C. Seidl3, F. Schmid5, M. Robillard6, H. Mikula4, J. Kristensen7, M. Barz3, A. Kjær2, M. Herth8 1Department of Drug Design and Pharmacology, University of Copenhagen, Denmark; 2Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 3Institute of Organic Chemistry, Johannes Gutenberg University, Germany; 4Institute of Applied Synthetic Chemistry, Technische Universität Wien (TU Wien), Austria; 5Institute of Physics, Johannes Gutenberg University, Germany; 6Tagworks Pharmaceuticals, Netherlands; 7Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 8Univesity of Copenhagen, Sweden Noninvasive imaging of CD38 using 64Cu-labeled F (ab)2 fragment from daratumumab in lymphoma models L. Kang1, D. Jiang2, W. Wei3, D. Ni2, J. Engle4, R. Wang1, W. Cai2 1Peking University First Hospital, China; 2University of Wisconsin-Madison, USA; 3Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA PET imaging of gastrin-releasing peptide receptor with a novel 68Ga-labeled bombesin analogue J. Lau, E. Rousseau, Z. Zhang, C. Uribe, H. Kuo, J. Zeisler, C. Zhang, D. Kwon, K. Lin, F. Benard BC Cancer Research Centre, Canada Development of 18F-fluoroglycosylated PSMA ligands with improved kidney clearance behavior R. Potemkin, B. Strauch, M. Geisthoff, T. Kuwert, O. Prante, S. Maschauer Department of Nuclear Medicine, Molecular Imaging, and Radiochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Germany
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Radiofluorination of a COX-1 specific ligand based on two nucleophilic addition strategies C. Taddei, V. Pike National Institute of Mental Health, USA Kit-like 18F-labeling using triazole-linked conjugates for [18F]aluminum monofluoride complexation M. Walther1, C. Neuber1, R. Bergmann1, J. Pietzsch2, H. Pietzsch1 1Helmholtz-Zentrum Dresden-Rossendorf, Germany; 2Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Germany The efficient preparation of radiolabeled aromatic amino acids via Cu-mediated radiofluorination of Ni-complexes A. Craig1, N. Kolks2, E. Urusova3, J. Zischler1, B. Neumaier1, B. Zlatopolskiy4 1Forschungszentrum Jülich GmbH, Germany; 2Jülich Research Centre (FZJ), Germany; 3Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Germany; 4Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany Cyclic ketals as precursors for 3-deoxy-3-[18F]-fluororibose and its derivatives M. Parker1, M. Evans, D. Wilson University of California, San Francisco, USA Radiofluorination of non-activated aromatic prosthetic groups for efficient synthesis of fluorine-18 labelled ghrelin(1-8) analogues M. Lazarakos1, M. Kovacs2, L. Luyt1 1University of Western Ontario, Canada; 2The Lawson Health Research Institute, Canada Development of pyridine-based precursors for direct labeling of biomolecules M. Richard1, M. Roche2, S. Specklin1, B. Kuhnast1 1Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 2Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris-Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, Orsay, France
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Abstracts-Oral
DOI: 10.1002/jlcr.3724
SUPPLEMENT ARTICLE
23rd International Symposium on Radiopharmaceutical Sciences Key n ote lecture 1 O-01 | Pioneers require a spirit of determination and challenge: Milestones of PET radiopharmaceutical development Tatsuo Ido Neuroscience Research Institute, Gachon University, South Korea
On August 16, 1976, the first challengeable study of a human brain function was initiated at UPenn with the positron emitting radiopharmaceutical, 18F‐FDG. This was the first successful research of the regional glucose consumption mapping in human brain. And this was also a successful example of collaboration between different institutions and different research fields (Brookhaven/nuclear chemistry, NIMH/neurology, and UPenn/nuclear medicine). This is the one of great milestone of nuclear medicine development and led to PET functional image analysis (brain function and tumor function) with the well‐designed radiopharmaceuticals. In 1982, researchers at Johns Hopkins Medical School and Uppsala University collaborated in the undertaking of another challenge: neuro‐receptor imaging (dopamine D2) of the in‐vivo human brain using 11 C‐methylspiperone. This was a second milestone for development of molecular imaging. After this, the compounds related to signal transduction (agonist, antagonist) were labelled with 11C or 18F and applied to determine synapse activity. Dopaminergic, serotonergic, cholinergic, histaminergic, GABAergic, opioid, and glutamatergic receptors are able to determine by this method. Also, positron‐labelled MAO inhibitor and ACh‐esterase inhibitor are applied to diagnosis of PD and AD. A third milestone is the development of the theranostic application of radiopharmaceuticals to tumors. The 67Ga/68Ga labelled to a monoclonal antibody of tumor or shortened peptide linked DOTA was applied simultaneously to PET diagnosis and the internal radiation therapy of tumor. In this purpose, 89Zr is also selected because of its longer half‐life
(78.4 hr). Recently highlighted works in “Brain PET” research are the imaging of amyloidal plaque and active tau protein for AD patient. 11C‐ and 18F‐labelled thioflavin analogs have been developed as amyloidal plaque markers. Active tau protein image by 18F‐THK compound (quinoline derivative) is closer related to cell denature than the amyloidal plaque. Another prominent work is the imaging of inflammation that may be important to find tissue denature at early stage in PD, AD, and other neurodegenerative diseases. For this purpose, TSPO (translocator protein) ligand (phenoxyphenyl acetamide and oxopurine derivative) is labelled with 11C and 18F. These pioneering studies do not proceed without the spirit of determination and challenge. Do not hesitate to try your idea. Carefully planned research will lead to new developments and, perhaps, to unexpected but positive results. Never give up easily, And, finally, enjoy your research efforts and results!
Keynote l ecture 2 O-02 | Clinical translation of molecular imaging in nuclear medicine: PUMCH experience Fang Li1,2,3,4 1
Peking Union Medical College Hospital, China; 2 Beijing Key Laboratory
of Molecular Imaging Diagnosis and Treatment of Nuclear Medicine, China; 3 China Association of Nuclear Medicine Equipment, China; 4
Chinese Journal of Nuclear Medicine and Molecular Imaging, China
Translational medicine is a rapidly growing discipline in biomedical research that aims to expedite the discovery of new diagnostic tools and treatments by using a multi‐ disciplinary “bench‐to‐bedside” approach. Molecular imaging, originated from the need to better understand fundamental molecular pathways inside organisms in a noninvasive manner, has a deep impact in translational medicine, contributing to the developments of new drugs
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SUPPLEMENT ARTICLES
and theranostic approaches. Nuclear medicine, a highlighted molecular imaging modality in clinics, has a rapid development in recent decades due to discoveries and clinical translation of novel molecular probes targeting various diseases. It promotes mutual translation of basic research and clinical practice and makes medical achievements. Peking Union Medical College Hospital (PUMCH) has a heritage in translational medicine since 1920s. When PUMCH was established, it has always been advocated that the combination of basic research and clinical practice, the “bench‐to‐beside” approach, must be implemented in guidelines of scientific research. Dr. Liu Shihao, a pioneer in endocrinology in China, was devoted to the research in mechanism of insulin and insulinoma in 1930s and researched in bone metabolism and osteodystrophy in 1930s; Dr. Song Hongzhao has turned choriocarcinoma, a highly malignant tumor with over 90% mortality rate, to a curable disease based on his work since 1950s. In the new era of PUMCH, translational medicine research is still the key point in scientific research, and the National Center for Translational Medicine is being set up. In Nuclear Medicine Department of PUMCH, translational study of molecular imaging is crucial in scientific development in recent decades. One of the most successful works in translational study in nuclear medicine in PUMCH is the somatostatin receptor‐based theranostic approach in neuroendocrine tumors. We have started somatostatin receptor imaging studies since 1990s and then made many achievements to improve the molecular agent, clinical application, and radioligand theranostics, which has greatly changed the clinical practice of neuroendocrine tumors. Studies in insulinoma in PUMCH have always taken the leading place worldwide since the 1st case of insulinoma in China was successfully resected in PUMCH in 1930s. Advances in nuclear medicine in recent years have greatly improved the preoperative detection rate of insulinoma, making the “occult” tumor into a “easy‐to‐find” disease. With such efforts in translational studies of molecular imaging, many clinical dilemmas as diagnosis of neuroendocrine tumors, localizing tumor induced osteomalacia, occult insulinomas, biochemical recurrent prostate cancer, etc, have been solved with the clinical translation in novel molecular imaging. The research achievements were highly glorified in international scientific fields and clinical practice. There are two highlighted roadblocks in translational medicine: the first block prevents basic research findings from being tested in a clinical setting; the second prevents proven interventions from becoming standard practice. The first translational block has been greatly improved with implementation of “bench‐to‐bedside” approach. However, the second roadblock is one of the most
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important issues that still need to be improved, in order to make translational study to authentic clinical significant achievements.
Radiolabeled compounds ‐ oncology (i ma gi ng ) s es si o n 1 O-03 | Bispecific anti‐GRPR/PSMA heterodimer for PET and SPECT imaging diagnostic of prostate cancer Anna Orlova1; Bogdan Mitran1; Zohreh Varasteh1; Ayman Abouzayed1; Sara Rinne1; Mats Larhed2; Vladimir Tolmachev1; Ulrika Rosenström1 1
Uppsala University, Sweden; 2 Department of Medicinal Chemistry,
Science for Life Laboratory, Uppsala University, Sweden
Objectives Prostate cancer (PCa) belongs to the most heterogeneous malignant tumours, both histologically and clinically. Correct staging of PCa is crucial for patient management and is an urgent clinical need. Imaging of PCa using radiolabelled agents targeting cell‐surface proteins overexpressed in PCa is a valuable approach to improve diagnostic accuracy. Gastrin‐releasing peptide receptor (GRPR) and prostate‐specific membrane antigen (PSMA) are cell surface targets strongly associated with PCa. GRPRs are expressed at high density in prostatic intraepithelial neoplasias, primary and invasive PCa. Expression of GRPR in PCa tends to decrease with further disease progression. Expression of PSMA is low in normal prostate tissue, but is increased in PCa with progression and is significantly up‐regulated as tumours dedifferentiate into higher grade, androgen‐insensitive and metastatic lesions. No one single imaging tracer provides a satisfactory staging in PCa patients due to changes in PCa cells phenotype in disease progression. Bispecific anti‐GRPR/PSMA molecular imaging agent will improve staging of the disease due to specificity to receptors overexpressed both in earlier and later stage of the PCa. Methods Bispecific anti‐GRPR/PSMA dimer NOTA‐DUPA‐RM26 was designed by combining the peptidomimetic PSMA inhibitor Glu‐urea‐Glu and the GRPR binding peptide RM26 (D‐Phe‐Gln‐Trp‐Ala‐Val‐Gly‐His‐Sta‐Leu‐NH2) via (CH2)8‐Glu (NOTA)‐(PEG)6 and produced using a combination of solid‐phase and manual peptide synthesis. NOTA‐DUPA‐RM26 was labelled with indium‐111 and gallium‐68. In vitro characterisation of radiolabelled NOTA‐DUPA‐RM26 (binding specificity, cellular processing, and affinity determination) was performed using
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PC‐3, LNCaP, and PC‐3‐pip cell lines expressing GRPR, PSMA and both GRPR and PSMA, respectively. In vivo specificity and biodistribution of the agent was studied in mice bearing PC‐3‐pip xenografts. Visualisation of GRPR/PSMA‐expression was done using [68Ga]Ga‐ NOTA‐DUPA‐RM26 (PET) and [111In]In‐NOTA‐DUPA‐ RM26 (SPECT). Results NH2‐(CH2)8‐Glu (Aloc protected)‐(PEG)6‐RM26 was synthesized using standard Fmoc‐peptide chemistry and coupled with (S)‐5‐(tert‐butoxy)‐4‐(3‐((S)‐1,5‐di‐tert‐ butoxy‐1,5‐dioxopentan‐2‐yl)ureido)‐5‐oxopentanoic acid.
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NOTA chelator was coupled after Aloc deprotection. Cleavage of the product and deprotection were followed by HPLC purification. The peptide was isolated via RP‐HPLC and LC‐MS confirmed the identity of the compound. Product purity was over 95%. NOTA‐DUPA‐ RM26 was labelled with 111In with radiochemical yield of 99 ± 1% and with 68Ga with radiochemical yield of 98.8 ± 0.3% (determined by ITLC). Both labelled products demonstrated high stability of radiometal‐NOTA complex and specific binding to receptors in vitro and in vivo. In PC‐3‐pip xenografts expressing PSMA and GRPR, tumour uptake of both [68Ga]Ga‐NOTA‐DUPA‐RM26 (8 ± 2%ID/
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g) and [111In]In‐NOTA‐DUPA‐RM26 (12 ± 2%ID/g) exceeded uptake in any other studied tissues already at 1 h p.i. Blood clearance of radiotracers was rapid via renal excretion. Interestedly, [68Ga]Ga‐NOTA‐DUPA‐RM26 had significantly lower activity uptake in tumours but significantly higher uptake in liver than [111In]In‐NOTA‐ DUPA‐RM26. Activity uptake decreased with time in all studied tissues including tumours. Tumour‐to‐blood ratios 1 h pi were 24 ± 3 and 29 ± 4, tumour‐to‐intestine 11 ± 3 and 9 ± 3, tumour‐to‐muscle 80 ± 30 and 90 ± 30, and tumour‐to‐bone 30 ± 10 and 35 ± 15, for [68Ga]Ga‐ NOTA‐DUPA‐RM26 and [111In]In‐NOTA‐DUPA‐RM26, respectively. With time, tumour‐to‐organ ratios increased; however, improvement 3 h pi was more pronounced for [111In]In‐NOTA‐DUPA‐RM26, and 24 h pi improvement was observed only for tumour‐to‐blood ratio for this agent. MicroPET/CT and microSPECT/CT images confirm the ex vivo data (Figure). Tumour uptake dominated images for both radiotracers. Tumour uptake of [111In]In‐ NOTA‐DUPA‐RM26) was lower when conjugate was co‐ injected with PSMA‐ or GRPR‐targeting agents, and tumour uptake of both conjugates decreased when simultaneously co‐injected with PSMA‐ and GRPR‐targeting agents. Imaging contrast improved with time for [111In] In‐NOTA‐DUPA‐RM26); however, activity uptake in tumours decreased. Conclusions Bispecific anti‐GRPR/PSMA dimer NOTA‐DUPA‐RM26 for imaging of PCa labelled with galium‐68 (for PET) and indium‐111 (for SPECT) demonstrated its capacity to visualize GRPR and PSMA expression already 1 h pi and deserve further investigations. ACKNOWLEDGMENTS This work was supported by the Swedish Cancer Society (CAN2014‐474 and CAN 2017/425) and the Swedish Research Council (2015‐02509).
Radiolabeled compounds ‐ oncology ( i m a g i n g ) se s s i o n 1 O-04 | Pretargeted tumor imaging with 64Cu‐ labeled ultrastable cross‐bridged macrocyclic complex Abhinav Bhise1; Swarbhanu Sarkar2; Phuong Huynh2; Woonghee Lee2; Jung Young Kim3; Kyo Chul Lee4; Jeongsoo Yoo1 1
Kyungpook National University, Republic of Korea; 2 Department of
Molecular Medicine, Kyungpook National University, Republic of Korea; 3
KIRAMS(Korea Institue of Radiological and Medical Sciences), Republic
of Korea; 4 KIRAMS, Republic of Korea
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Objective Tumor pretargeting is a promising strategy for cancer diagnosis and therapy. It has been implemented successfully in different preclinical models with long circulating, highly specific monoclonal antibodies.1,2 The Diels‐ Alder reaction between tetrazine and strained alkene dienophile was found to be most promising click ligation variant for the biorthogonal reaction due to its high reaction rate, and absolute selectivity under in vivo condition. Cu‐64 has a mid‐long half‐life of 12.7 h, and researchers can allow the radiolabeled ligands to circulate enough long for better tumor‐to‐background ratio.3 In this case, the in vivo stability of radiolabeled ligand also plays key roles. Radiolabeled chelator must maintained its integrity under in vivo condition allowing no or minimal demetallation of free copper(II) ions from complexes. To address this issue, herein we demonstrate a new class of propylene cross‐bridged chelator, PCB‐TE2A‐tetrazine, which can maintain its in vivo stability until imaging time points and give excellent tumor‐to‐background ratio in antibody based pretargeted imaging. Methods The antibody was modified with transcyclooctene (TCO) and injected intravenously into Balb/c nude mice bearing MDB‐MB‐231 tumor xenograft. PCB‐TE2A‐ tetrazine was radiolabeled with 64Cu and injected to the same mice after 48 h injection of the antibody. The biodistribution was performed at 4 h and 8 h post‐ injection. Results The radiolabeling of PCB‐TE2A‐tetrazine with Cu‐64 was conducted at 80°C and isolated by HPLC in excellent radiochemical yield, >95%. Biodistribution at 4 h and 8 h postinjection showed tumor uptake of 25.37 and 25.15 %ID/g, respectively, with high tumor‐to‐organ ratios; tumor‐to‐muscle, tumor‐to‐blood, tumor‐to‐liver, and tumor‐to‐kidney ratio was 558, 128, 11, and 4, respectively, at 8 h post‐injection of the radiolabeled chelator. Conclusions The first demonstration of the 64Cu‐labeled cross‐bridged chelator in antibody pretargeting system was achieved successfully via inverse electron‐demand Diels‐Alder cycloaddition between tetrazine and transcyclooctene. Further animal PET imaging studies are going on and will be also presented. ACKNOWLEDGMENTS This work was supported by NRF (2016R1A2B4011546, 2013R1A4A1069507, 2017M2C2A1014006, 2017M2A2A 6A02018506, 2017R1D1A1B03033974, HI17C0221, and KRF 2016H1D3A1907667) and BK21 Plus KNU Biomedical Convergence Program, Korea.
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FIGURE 1
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Biodistribution data in MDA‐MB‐231 xenograft tumor model
R EF E RE N C E S 1. Patra M, Zarschler K, Pietzsch H‐J, Stephan H, Gasser G. Chem. Soc. Rev., 2016, 45, 6415‐6431. 2. Bailly C, Bodet‐Milin C, Rousseau C, Faivre‐Chauvet A, Kraeber‐ Bodéré F, Barbet J. EJNMMI Radiopharmacy and Chemistry, 2017, 2:6. 3. Zeglis BM, Sevak KK, Reiner T, Mohindra P, Carlin SD, Zanzonico P, Weissleder R, Lewis JS. J. Nucl. Med. 2013, 54, 1389–1396.
Radiolabeled compounds ‐ oncology ( i m a g i n g ) se s s i o n 1 O-05 | Targeting CD206+ tumor‐associated macrophages using a finely tuned albumin nano‐platform for earlier detection of breast cancer metastases Ji Yong Park1; Hyewon Chung2; Kyuwan Kim1; Minseok Suh1; Seung Hyeok Seok2; Yun‐Sang Lee3 1
Seoul National University, College of Medicine, Republic of Korea; 2 Seoul
National University, Republic of Korea; 3 Seoul National University Hospital, Republic of Korea
Introduction Currently, applied imaging modalities are limited by difficulties in detection of small metastatic lesions at an early‐ stage, thus missing the opportunity for an optimal response to therapeutic interventions. Given the earlier infiltration of CD206‐expressing tumor associated macrophages (CD206+ TAMs) than cancer cells in metastatic site, noninvasive imaging of CD206+ TAMs has a strong implication for earlier detection of metastasis in clinic. Here, we delineate the noninvasive detection of lung metastases using 111In and fluorescence labeled mannosylated human serum albumin (111In‐MSA‐FL), which binds to CD206, in orthotopic breast cancer xenograft models. The SPECT/CT images with 111In‐MSA‐FL demonstrates the strong correlation between quantitative uptake and metastatic burden and ultimately enables the identification of early‐stage metastatic lesions that are not discernible under standard imaging modalities including [18F]FDG‐PET/MRI.
Methods To synthesize a CD206‐targeted imaging probe that enabled the noninvasive imaging of CD206+ TAMs in vivo, the clickable albumin platform was prepared for conjugation of mannose, fluorescence dye and/or 111In. The number of azadibenzocyclooctyne (ADIBO) group for click reaction on the albumin platform was 8.4 ± 0.32, which was degree of functionalization (DOF) and calculated using UV‐Vis spectrophotometric method. Using this albumin platform, 5 molar excess of 1‐O‐(2‐(2‐ (2‐azidoethoxy)ethoxy)ethoxy)‐alpha‐D‐mannopyranoside (Man‐N3) was mixed with the ADIBO modified albumin platform. The number of mannosyl group on albumin platform was 4.1 ± 0.26, and then this mannosylated human serum albumin (MSA) was used for fluorescence (FNR648) labeling and/or 111In labeling to make MSA‐ FL or 111In‐MSA‐FL. The sizes of MSA derivatives were measured using dynamic light scattering (DLS) method and to be almost same with human serum albumin. Results First, 111In‐MSA‐FL was injected intravenously into this mice with orthotopic xenografts, and the SPECT/CT images were taken at 24 h post‐injection. In addition to substantial uptake in tumor, particularly tumor stroma at day 14, we demonstrated a clearly higher uptake in lung from 4T1‐bearing mice compared to tumor‐free mice at day 28. We next assessed the capability of the established 111 In‐MSA‐FL‐based CD206 imaging to discern metastatic lesion noninvasively at early stage. The 4T1‐bearing mice were imaged with both SPECT/CT using 111In‐MSA‐FL and PET/MRI using [18F]FDG from day 14 to 28 after cancer cell injection. Longitudinal monitoring showed the signal intensity at the future metastatic lung was gradually increased until day 28 when substantial metastatic nodules were observed, which was consistent with the flow cytometry analysis. Notably, we found 111In‐MSA‐FL signal in lung was higher compared to tumor‐free mice as early as day 14 and 21 post tumor inoculation as assessed by images‐based visual analysis (Figure 1a, b) and quantification of 111In‐MSA‐FL accumulation in dissected lung (Figure 1d) while there was no significant difference in [18F]FDG PET/MRI imaging between 4T1‐bearing mice and tumor‐free mice at this time (Fig. 1 a‐c). Thus, we
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demonstrated 111In‐MSA‐FL‐based imaging of CD206+ TAMs enabled the earlier detection of lung metastases than [18F]FDG PET/MRI. Conclusions Our results provide robust evidence that targeting CD206+ TAMs with 111In‐MSA‐FL could be a remarkable breakthrough to overcome the challenges in the early detection of metastasis and facilitates earlier therapeutic interventions. ACKNOWLEDGEMENTS This work was carried out by the research fund supported by the fund project of Park Yang Sook ‐ Chung Yung Ho in Seoul National University. Yun‐Sang Lee was supported by Radiation Technology R&D program (NRF‐ 2017M2A2A7A01021401) through the National Research Foundation of Korea (NRF).
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Radiolabeled compounds ‐ oncology (i ma gi ng ) s es si o n 1 O-06 | Improving pharmacokinetics of 99mTc‐ ref with PEG linkers for HER2‐targeted SPECT imaging of breast cancer Shuaifan Du1; Hannan Gao1; Chuangwei Luo1; Guangjie Yang1; Qi Luo2; Bing Jia1; Jiyun Shi3; Fan Wang1,2 1
Peking University, China; 2 Institute of Biophysics, CAS, China; 3 Institute
of Biophysics, CAS, China
Objectives Evaluating the expression status of human epidermal growth factor receptor‐2 (HER2) could predict the
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response of HER2‐targeted therapy in breast cancer. Previously, a HER2‐targeted H6F peptide (sequence: YLFFVFER) was developed as a SPECT imaging probe for HER2‐positive breast tumor. However, the 99mTc‐H6F probe was strictly limited for further clinical application because the poor water solubility and metabolic stability, as well as high gallbladder uptake. In this study, the Retro‐inverso ppD‐peptide (ref peptide full sequence: refvffly) of H6F was designed as a novel SPECT imaging probe, and PEGylation was further introduced into the probe to improve its metabolic stability and pharmacokinetics in vivo, so as to develop a promising noninvasive tool for discriminating HER2 status in breast cancer, and guiding the HER2‐targeted antibody treatment. The PEG4‐ref, PEG12‐ref, and PEG24‐ref peptides were designed and synthesized. Cell fluorescent staining and surface plasmon resonance (SPR) studies were firstly performed to validate the HER2‐binding affinity of ref peptides. Then, the PEG4‐ref/PEG12‐ref/PEG24‐ref peptides were radiolabeled with 99mTc for in vivo evaluation 99m Tc‐PEG4‐ref/99mTc‐PEG12‐ref/99mTc‐ (termed as PEG24‐ref). The biodistribution and SPECT imaging of 99m Tc‐PEG4/PEG12/PEG24‐ref were performed in HER2‐ positive SKBR3 human breast tumor bearing mice.
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Blocking group and HER2‐negative MCF7 human breast tumor group were set as controls. Results Cell staining and SPR results showed that ref peptides had high HER2‐binding affinity in vitro. NanoScan SPECT/CT imaging results showed that the HER2‐positive SKBR3 breast tumors could be clearly visualized with all three ref peptide based probes. Besides tumor, kidneys showed high accumulation followed by the liver. The biodistribution results were consistent with the imaging results. All three tracers gave enhanced tumor uptake, compared to the previous tracer 99mTc‐H6F (1.48 ± 0.18 %ID/g). Among them, the 99mTc‐PEG4‐ref showed the highest tumor uptake (3.76 ± 0.56 %ID/g) at 0.5 h p.i., but with highest kidney uptake (57.07 ± 6.55 %ID/g) and liver uptake (6.57 ± 0.94 %ID/ g) compared to that of further PEGylated 99mTc‐PEG12‐ ref (tumor: 3.29 ± 0.20 %ID/g, kidney: 35.52 ± 5.82 %ID/ g, liver: 2.57 ± 0.67 %ID/g) and 99mTc‐PEG24‐ref (tumor: 2.82 ± 0.43 %ID/g, kidney: 36.07 ± 2.10 %ID/g, liver: 2.33 ± 0.23 %ID/g), respectively. The T/NT ratios, especially Tumor/Blood, Tumor/Liver, Tumor/Muscle, and Tumor/Lung of 99mTc‐PEG24‐ref, were enhanced compared to that of 99mTc‐PEG4‐ref. In general, the further
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PEGylation of 99mTc‐PEG24‐ref resulted in improved in vivo pharmacokinetic properties but with decreased tumor uptake in comparison of 99mTc‐PEG4‐ref. The tumor uptake of 99mTc‐PEG24‐ref was notably decreased in blocking and HER2‐negative MCF7 tumor groups, indicating the HER2‐specific targeting capability. Conclusions 99m Tc‐PEG24‐ref is a promising molecular probe for HER2‐ positive breast cancer imaging, which showed enhanced tumor targeting capability and improved in vivo stability, compared to previous 99mTc‐H6F. The further PEGylation of 99mTc‐PEG24‐ref given its more improved in vivo biocompatibility, pharmacokinetic properties, resulted in better T/NT ratios, in comparison of 99mTc‐PEG4‐ref. This novel tracer possesses great potential for clinical application in screening HER2‐positive breast cancer patients and monitoring the efficacy of HER2 antibody treatment. The further investigation is still in progress. Figure 1: Representative nanoScan SPECT/CT images of (a) 99mTc‐ PEG4‐ref (b) 99mTc‐PEG12‐ref (c) 99mTc‐PEG24‐ref in SKBR3 (HER2+) tumor model, and (d) 99mTc‐PEG24‐ref in SKBR3 (HER2+) v.s. MCF7 (HER2−) and SKBR3 (Block) tumor models. (e) Chemical structures of 99mTc‐ HYNIC‐PEGn‐ref. (f) Biodistribution of 99mTc‐PEG4/12/24‐ ref in SKBR3 tumor model, compared to previous probe 99m Tc‐PEG4‐H6F. (g) T/NT ratios of 99mTc‐PEG24‐ref v.s. 99m Tc‐PEG4‐ref in SKBR3 tumor model.
Radiochemistry ‐
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O-07 | Generation of 18F‐metal fluorides from [18F]HF generated by acidic QMA elution and application towards 18F‐fluorination/ring‐ opening of complex epoxides Stefan Verhoog1; Allen Brooks2; Wade Winton2; Andrew Mossine2; Melanie Sanford2; Peter Scott3 1
Merck & Co Inc, USA; 2 University of Michigan, USA; 3 The University of
Michigan, USA
Objectives Anhydrous hydrogen fluoride (HF) is an effective fluorinating reagent with a unique reactivity profile due to its high acidity and its ability to form hydrogen bonded complexes with weak, non‐basic hydrogen bond acceptors. It is also an excellent reagent for the synthesis of well‐ defined metal fluoride salts, starting from a variety of different basic metal salt precursors.1 Previous work in our group has shown that [18F]HF can be easily generated through elution of [18F]F− trapped on a QMA, with the elution efficiency being related to the pKa of the acid
used.2 Our objective in this work was to use the [18F]HF thus produced in the synthesis of reactive 18F‐metal fluorides with a unique reactivity profile that is complementary to the reactivity of [18F]F− generated under more traditional, basic conditions in the presence of kryptand. As an example of such reactivity, we developed the fully automated 18F‐fluorination/ring opening of complex, sterically hindered epoxides using a [18F]FeF‐species generated from a combination of [18F]HF and Fe (acac)3. Methods Fluorine‐18 was produced by the 18O(p, n)18F nuclear reaction using a GE PETTrace cyclotron and delivered to a GE TRACERLab FXFN automated radiochemistry synthesis module followed by trapping on a Waters QMA SepPak Light Carb. This was followed by elution (as [18F]HF) with a solution of TFA in CH3CN/H2O 4:1 into a glassy carbon reactor, which had been charged with Fe (acac)3. The reaction was heated at 80°C for 10 min to trap [18F]HF and generate a [18F]FeF‐species, followed by azeotropic drying under vacuum/inert gas at 110°C. A solution of epoxide in dioxane was added, followed by heating at 120°C for 20 min under autogenous pressure. After cooling to 60°C, HPLC buffer was added and the mixture was purified by semi‐Prep HPLC to provide the 18F‐fluorohydrin product. Radiochemical identity and purity were confirmed using analytical HPLC, monitoring with UV and radiation detectors. Results Preliminary results show the synthesis and isolation of 4 complex 18F‐fluorohydrin products using a fully automated procedure in which acidic elution is utilized to generate [18F]HF, which is subsequently trapped as an [18F]FeF‐species. This species is then azeotropically dried to provide an effective reagent for 18F‐fluorination/ring‐opening of complex, sterically hindered epoxides (Figure 1). The reaction did not proceed when [18F] KF in combination with Kryptofix K222 was used as the 18 F‐fluorinating reagent. Conclusions A fully automated procedure was developed for the generation of [18F]HF through acidic elution, followed by trapping as a [18F]FeF‐species. This reagent was successfully used to open complex, sterically hindered epoxide substrates to provide the corresponding 18F‐fluorohydrins which were isolated after HPLC purification. The 18 F‐fluorohydrin products were synthesized in high radiochemical purity and in quantities sufficient for (pre‐)clinical imaging. The use of elution under acidic conditions to generate [18F]HF allows for synthesis of 18F‐metal fluorides with unique reactivity, which enable challenging 18 F‐fluorination reactions with complementary scope compared to basic [18F]F−/kryptand complexes.
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ACKNOWLEDGEMENTS This work was supported by NIH grant R01EB021155 from NIBIB. R EF E RE N C E S 1. Scholz, G.; Kemnitz, E. Modern Synthesis Processes and Reactivity of Fluorinated Compounds, 2017, 609‐649 2. Verhoog, S.; Brooks, A. F.; Mossine, A. V.; Scott, P. J. H. J. Nucl. Med. 2018, 59, Supplement 1:1064
Radiochemistry ‐
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O-08 | Pretargeted PET imaging using a dual click
18
F‐labeling strategy
Johanna Steen1; Christoph Denk2; Jesper Jørgensen3; Kamilla Nørregard3; Raffaella Rossin5; Martin Wilkovitsch2; Dennis Svatunek2; Patricia Edem6; Claudia Kuntner4; Thomas Wanek4; Marc Robillard5; Jesper Kristensen6; Andreas Kjær3; Hannes Mikula2; Matthias Herth7 1
Department of Drug Design and Pharmacology, University of
Copenhagen, Denmark; 2 Institute of Applied Synthetic Chemistry, Technische Universität Wien (TU Wien), Austria; 3 Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 4 Health and Environment Department, Biomedical Systems, Austrian Institute of Technology (AIT), Austria; 5 Tagworks Pharmaceuticals, Netherlands; 6 Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 7 Univesity of Copenhagen, Sweden
Objectives Pretargeted immuno‐positron emission tomography (PET) imaging using the bioorthogonal ligation between a radiolabeled tetrazine and a monoclonal antibody (mAb) modified with trans‐cyclooctene (TCO) allows for the use of short‐lived radionuclides, such as fluorine‐18. However, direct 18F‐fluorination of
tetrazines has been reported to be tedious due to the sensitivity of the tetrazine scaffold.1,2 Thus, the objective of the present study was to explore a suitable indirect labeling approach, by which the combination of different building blocks would give us access to a library of 18F‐ labeled tetrazines with high structural diversity, including reactive structures that have previously proven difficult to access. The newly developed 18F‐labeled tetrazines were going to be used to image the tumor accumulation of the TAG72‐targeting mAb CC49 in human colon carcinoma.3 Methods The Cu‐catalyzed azide‐alkyne [3 + 2] cycloaddition (CuAAC) was identified as a strategy to access a tetrazine library. The library was made up from alkyne‐modified tetrazines in combination with 18F/19F‐fluorinated azides (Figure 1). The reference compounds were evaluated in an in‐house developed blocking assay to assess their potential as radioligands for pretargeting. The assay was performed in nude BALB/c mice bearing subcutaneous colon carcinoma LS174T xenografts. The mice were pretreated with TCO‐modified CC49 (CC49‐TCO, 100 μg, 6.7 nmol, ~7 TCO/mAb) 72 h prior to the experiments, in which the ability of the tetrazines to block a previously described 111In‐labeled tetrazine was studied.4 All 18F‐labeled tetrazines were evaluated in naïve mice for stability and biodistribution assessment. Subsequent pretargeted PET studies were performed using the same tumor model and mAb as for the blocking assay. PET/CT imaging was performed 1 h after tracer administration to determine tumor uptake. Results The 18F‐labeled tetrazines were successfully obtained via the CuAAC in decay corrected radiochemical yields up to 68% and high radiochemical purity (>94%). The blocking effects of their non‐radioactive analogs were correlated to parameters such as reaction kinetics and lipophilicity. In general, high rate constants >200 M−1 s−1 with a calculated distribution coefficient
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(clogD7.4) below 0.5 were favorable for a promising in vivo behavior. These results and biodistribution studies guided the selection of a group of 18F‐labeled tetrazines that was evaluated in pretargeted PET experiments. The results from the PET studies were in line with the predicted outcome from the assay. The tetrazine with the lowest clogD7.4 and a high rate constant (>200 M−1 s−1) was identified as a promising lead compound (Figure 1, tetrazine 3 combined with azide [18F]c) with a tumor uptake of 2.08 ± 0.24% ID/g. High radioactivity levels were observed in the blood pool (tumor‐to‐blood ratio was 0.75), arising from the ligation between 18F‐labeled tetrazine and the still circulating CC49‐TCO. Conclusion A small library of structurally diverse 18F‐labeled tetrazines was accessible via the CuAAC. Evaluation of the library revealed a tetrazine lead compound, which was able to bind to the mAb at the tumor‐site under high molar activity conditions. However, residual mAb in the blood remains a challenge. Current efforts are directed toward exploring clearing or masking agents, as well as developing a group of second‐generation tetrazines with higher hydrophilicity to potentially increase the tumor uptake further. ACKNOWLEDGMENTS The authors greatly acknowledge the H2020 project Click‐it, under grant agreement no. 668532, for financial support and the technical staff at the Department of
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Clinical Physiology, Nuclear Medicine and PET at Rigshospitalet, Denmark. RE FER EN CES 1. Denk C. et al., Angew. Chem. Int.Edit., 2014, 53, 9655–9659. 2. Li Z. et al., Chem Commun., 2010, 46, 8043–8045. 3. Rossin, R. et al., Bioconjug. Chem., 2013, 24, 1210‐1217. 4. Rossin R. et al., Angew. Chem. Int. Edit., 2010, 49, 3375–3378.
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O-09 | Development of high affinity 18F‐ labelled radiotracers for PET imaging of the adenosine A2A receptor Thu Hang Lai1; Susann Schroeder1; Friedrich‐Alexander Ludwig2; Steffen Fischer3; Rares Moldovan4; Matthias Scheunemann1; Sladjana Dukic‐Stefanovic1; Winnie Deuther‐Conrad1; Jorg Steinbach1; Peter Brust1 1
Helmholtz‐Zentrum Dresden‐Rossendorf, Germany; 2 Department of
Neuroradiopharmaceuticals, Institute for Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum Dresden‐Rossendorf, Research Site Leipzig, Germany; 3 HZDR, FS Leipzig, Germany; 4 Institute of Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum Dresden Rossendorf, Germany
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Objectives The adenosine A2A receptor (A2AR) is a G‐protein‐ coupled‐receptor which is mainly expressed in the basal ganglia (including striatum) of the brain and in cells of the immune system. Radiotracers for A2AR imaging have emerged as promising candidates for the diagnosis of neurodegenerative and neurooncological diseases. Aiming at the development of such radiotracer with improved molecular imaging properties, a library of 21 fluorinated pyrazolo[2,3‐d]pyrimidine derivatives was synthesized based on a recently published lead compound [1]. Among those, the high affinity 4‐fluorobenzyl derivate 1 (Ki (hA2A) = 5.3 nM; Ki (hA1) = 220 nM) and the 2‐fluorobenzyl derivate 2(Ki (hA2A) = 2.1 nM; Ki (hA1) = 147 nM) were chosen for 18F isotopic labelling although the introduction of 18F at non‐activated aromatic positions is challenging. Herein, we report on the radiosyntheses of [18F]1 and [18F]2 via an alcohol‐ enhanced copper‐mediated one‐step radiofluorination and their first biological evaluation. Methods Three different labelling strategies for the synthesis of [18F]1 have been investigated (Figure 1). The first two were using [18F]fluorobenzaldehyde ([18F]B) as intermediate, which was produced by nucleophilic radiofluorination of a trimethylammonium precursor of type A (step a). Compound [18F]B was used either in a reductive amination reaction (step b) or it was further reduced to the corresponding alcohol (step c) followed by an Appel bromination to get [18F]C (step d), which
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was finally used in a benzylation reaction (step e). The third strategy, a one‐step approach, started from the boronic acid pinacol ester precursor of type D employing [18F]TBAF and Cu (OTf)2(py)4 in n‐BuOH/ DMA (step f). The specific binding of [18F]1 and [18F]2 was evaluated in vitro by autoradiography of mice brain slices using 1, 2 and ZM241385 as different blocking agents. Results The two‐ and four‐step labelling strategies resulted in an overall radiochemical yield of only 1.4% and 10%, respectively, for [18F]1 (non‐isolated). Therefore, [18F]1 and [18F]2 were prepared by an alcohol‐enhanced copper‐ mediated one‐step radiolabelling approach starting from the corresponding boronic acid pinacol ester precursor D. Compound [18F]1 was obtained with a radiochemical yield of 52 + 7% (n = 5, EOB), a molar activity of 135 + 64 GBq/μmol (n = 4, EOS), and a radiochemical purity of >98%. Compound [18F]2 was synthesized with a radiochemical yield of 9 + 1% (n = 2, EOB), a molar activity of 132 GBq/μmol (n = 1, EOS), and a radiochemical purity of >98%. In vitro autoradiography performed with [18F]2 showed high binding in the striatum, which could be blocked by selective A2AR ligands thus proving the specificity of the new radiotracer (Figure 1). Conclusions An efficient copper‐mediated one‐step radiolabelling procedure was established for two new high affinity A2AR radiotracers. In a first in vitro study on mice brain slices,
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[18F]2 demonstrated excellent imaging properties. Further biological in vitro and in vivo investigations are needed to completely evaluate the potential of both A2AR radiotracers. ACKNOWLEDGMENTS This work has been supported by the the European Regional Development Fund and Sächsische Aufbaubank (project no. 100226753).
R EF E RE N C E S 1. Gillespie et al., Bioorg. Med. Chem. Lett. 2008, 18, 2924‐2929.
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O-10 | Preparation of [18F] fluoroalkenyliodonium salts and their application for radiolabeling by cross‐coupling reactions 1
2
3
Swen Humpert ; Marcus Holschbach ; Dirk Bier ; Boris Zlatopolskiy4; Bernd Neumaier1 1
Forschungszentrum Jülich GmbH, Germany; 2 Foschungszentrum Jülich
GmbH, Germany; 3 Forschungszentrum Juelich, Germany; 4 Institute of
Results Under optimized conditions (KHCO3, K2.2.2, 67% aq. DMSO, 75°C) [18F]FHexI+X– salts were prepared in RCYs of about 60% (HPLC) within 10 min. Remarkably, time consuming azeotropic drying was not necessary. Radiolabeling of the phenylethynyl substituted precursors also furnished the respective 18F‐labeled iodonium salts although in lower RCYs of 20% to 30% (HPLC). The respective counter ion (OTs–, OMs–, BF4–, TFA–) did not have a significant influence on RCYs. [18F]FHexI+OTs– was purified by HPLC followed by solvent exchange and thereafter used for subsequent cross‐coupling reactions. Sonogashira, Stille, and Suzuki reactions afforded the respective radiolabeled products as pure Z‐isomers in RCYs of 61% to 74% (HPLC) within 3 to 10 min at ambient temperature. In the case of the Heck cross‐coupling the corresponding 18F‐fluorinated diene was prepared in RCY of 27 ± 2% as a mixture of E/Z isomers. Table 1: Summary of cross coupling reaction conditions Cross‐coupling
Catalyst
Base
Solvent
RCY
Sonogashira
Pd (OAc)2 + 2 PPh3, CuI
TEA
DMF/ water
61 ± 10%
Stille
Pd (PPh3)4
‐
dioxane/ water
68 ± 2%
Suzuki
Pd (OAc)2 + 1 PPh3
K2CO3
dioxane/ water
74 ± 2%
Heck
Pd (OAc)2 + KI
KHCO3
DMF/ water
27 ± 2%
Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany
Objective (Fluoroalkenyl)(aryl)iodonium salts are valuable building blocks for Pd‐catalyzed cross‐coupling reactions [1]. These prosthetic groups are easily available via nucleophilic addition of fluoride to the respective (alkynyl)(aryl) iodonium salts under exceptionally mild conditions [2]. Herein we report the preparation of 18F‐labeled (2‐ fluorohexen‐1‐yl)(aryl)iodonium salts ([18F]FHexI+X–) and their application in various Pd‐catalyzed cross‐ coupling reactions. Finally, [18F]FHexI+OTs– was used for the site selective labeling of clinically relevant compounds and peptides. Methods (Alkynyl)(aryl)iodonium salts were radiolabeled using [18F]fluoride in aqueous media in the presence of different bases and K2.2.2. The reaction conditions were optimized with respect to different parameters including reaction temperature, time, solvent, precursor amount and counter ion. After isolation, [18F]FHexI+OTs– was applied in Pd‐catalyzed cross‐couplings with different model substrates. Additionally, radiofluorinated amino acid derivatives as well as a PSMA ligand potentially suitable for the detection of prostate carcinoma lesions were prepared starting from [18F]FHexI+OTs–.
In particular, the one‐pot Sonogashira cross‐coupling reaction turned out to be very fast and robust under very mild conditions. Therefore, this reaction was selected to demonstrate the applicability of [18F]FHexI+ for the labeling of biomolecules. Nine ethynyl‐substituted amino acid derivatives were conjugated with [18F]FHexI+OTs– using the Sonogashira reaction affording the respective radiolabeled enynes in RCYs of 38% to 88% (HPLC). Furthermore, a novel 18F‐labeled PSMA ligand was prepared in an isolated RCY of 40% in two steps within 35 min. Conjugation of [18F]FHexI+OTs– to a suitably modified model dipeptide (H‐Arg‐Pra‐OBn) afforded the corresponding conjugate in 61% RCY based on isolated [18F] FHexI+OTs– using only 50 nmol peptide precursor. Conclusion The novel radiolabeled prosthetic group [18F]FHexI+OTs– is easily available in aqueous media obviating any evaporation steps. Thus, [18F]FHexI+OTs– can be used in Pd‐ catalyzed cross‐coupling reactions as a fast, high yielding, site specific and versatile procedure for the preparation of clinically relevant PET tracers. [1] Yoshida et al., Tetrahedron 62 (2006) 8636‐8645 [2] Nguyen et al., Tetrahedron 67 (2011) 3434‐34939
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Radiochemistry ‐
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F S ess io n 1
O-11 | High molar activity [18F] trifluoromethane for PET tracer synthesis Anna Pees1; Maria Vosjan2; Vincent Tadino3; Jin Young Chai4; Hyojin Cha4; Dae Yoon Chi4; Albert Windhorst5; Danielle Vugts1 1
Amsterdam UMC, VU University, Netherlands; 2 BV Cyclotron VU,
Netherlands; 3 ORA Neptis, Belgium; 4 Department of Chemistry, Sogang University, Republic of Korea; 5 VU University Medical Center, Netherlands
Objectives Fluorine‐18 due to its favourable properties is a radionuclide frequently used for PET imaging. The trifluoromethyl group is a very prominent motif in biologically active compounds, and therefore labelling of this motif with fluorine‐18 holds great promise for the synthesis of novel PET tracers. A few methods for the labelling by [18F]trifluoromethylation have been explored in the past.1–4 However, the methods suffer from low to moderate molar activities (MA) of 0.1‐30 GBq/μmol. Previous
reports suggest that the low MA values are caused by precursor degradation in presence of water and base originating from the [18F]fluoride drying procedure.2 As a high molar activity (>100 GBq/μmol) is crucial for imaging of receptors with low density, our aim was to optimize the [18F]fluoroform synthesis towards a high MA by optimizing the reaction parameters and controlling the amount of base‐cryptand complex present in the reaction. We envisioned to achieve this by implementing [18F] triflyl fluoride as gaseous [18F]fluoride source.5 Methods [18F]Fluoride was eluted from a 30‐PS‐HCO3 cartridge with 500 μL 0.1 M K2SO4 in H2O into a vessel containing 850 μL DMF. Next, bistriflate 1 (0.015 mmol) was added, resulting in the formation of [18F]triflyl fluoride, which was instantaneously distilled at 40°C into a solution of base‐cryptand complex in a polar aprotic solvent.5 Upon addition of precursor 3 or 4, [18F]fluoroform 5 was formed. The [18F]fluoroform was further reacted with benzophenone 6 to form UV active product 7 for MA determination by HPLC analysis. Reaction conditions were systematically varied: type and amount of base‐ cryptand complex, solvent, type and amount of precursor,
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TABLE 1 Precursor stability, RCY, and MA for different reaction conditions; Solvent: MeCN, reaction time: 10 min, 1 μmol precursor, n. d. = not determined, dc = decay corrected, EOS = end of synthesis.
entry
K2CO3/K222 (μmol)
precursor
Temp. (°C)
1
1.5/3.5
3
20
18 −
Precursor stability (%)
RCY of 5 (%, dc)
MA (GBq/μmol at EOS)
5
24 ± 5
15 ± 3
n.d.
F (GBq)
2
0.15/0.35
3
20
5
82 ± 0
25 ± 1
n.d.
3
1.5/3.5
3
80
5
0±0
23 ± 2
4±2
4
0.15/0.35
3
80
5
71 ± 0
44 ± 1
18 ± 2
5
0.15/0.35
3
80
25
n.d.
35 ± 4
78 ± 38
6
0.15/0.35
4
80
25
n.d.
40 ± 4
120 ± 15
reaction temperature and time. In addition, the stability of precursor 3 as well as the radiochemical yield (RCY) and the MA of [18F]fluoroform 5 were investigated for the different reaction conditions. Results and discussion Gaseous [18F]triflyl fluoride can, in the presence of only trace amounts of base in an array of solvents, be converted to dry [18F]fluoride, which gives full flexibility for optimizing the reaction conditions of the [18F]fluoroform synthesis. An excerpt of the results of the stability of precursor 3 as well as the RCY and the MA of [18F] fluoroform 5 is shown in Table 1. It was found that precursor stability and MA of [18F]fluoroform were strongly affected by the amount of base‐cryptand complex (entries 1‐2 and 3‐4). This supports the hypothesis that low MA results from precursor degradation under basic reaction conditions. The RCY was mainly affected by the reaction temperature (entry 1‐4). With the optimized reaction conditions, we obtained [18F]fluoroform from precursor 4 with a MA up to 120 ± 15 GBq/μmol (Table 1, entry 6). Conclusion Implementing the novel [18F]fluorination reagent [18F] triflylfluoride resulted in excellent control of the reaction conditions for the [18F]fluoroform formation and resulted in a MA of >100 GBq/μmol. This new procedure opens the way for the synthesis [18F]trifluoromethylated PET tracers with high MA.
ACKNOWLEDGEMENTS The project is financially supported by The Netherlands Organization of Scientific Research (NWO) and BV Cyclotron VU. RE FER EN CES 1. V.d. Born, D. et al., Angew. Chem., Int. Ed., 2014, 53, 11046–11050 2. Ivashkin, P. et al. , Chem. Eur. J., 2014, 20, 9514–9518 3. Rühl, T. et al., Chem. Commun., 2014, 50, 6056–6059 4. Huiban, M. et al., Nat. Chem., 2013, 5, 941–944 5. Pees, A. et al., Chem. Commun., 2018, 54, 10179–10182.
R a d i o ch e m i s t r y ‐
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F se s s i o n 1
O-12 | Synthesis and evaluation of [18F] canagliflozin for imaging SGLT‐2‐transporters in diabetic patients Khaled Attia; Ton Visser; Jasper Steven; Riemer Slart; Ines Antunes; Sjoukje van der Hoek; Philip Elsinga; Hiddo Heerspink University Medical Center Groningen, Netherlands
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Objective Type 2 diabetes affects more than 390 million people (1). Canagliflozin, an FDA approved drug, is a sodium glucose co‐transporter 2 inhibitor (SGLT‐2) indicated for the treatment of type 2 diabetes. It lowers plasma glucose by increasing urinary glucose excretion (2). Treatment response to canagliflozin is highly variable between patients: some patients show marked reductions in plasma glucose whereas others do not. For a study to correlate biodistribution of canagliflozin in patients to drug response, we have developed a synthesis method for [18F] canagliflozin. Methods Canagliflozin precursor equipped with a pinacol aryl boronic ester moiety has been successfully prepared by Syncom BV and its synthesis is depicted in Scheme 1. The precursor was prepared via a seven‐step synthetic route starting from thiophene 1, purified by automated reverse phase column chromatography and fully characterized. [18F]Canagliflozin has been successfully obtained by reaction of its boronic ester precursor with 18F‐Fluoride (Figure 1A). Several parameters such as temperature, solvents and reaction time were tested in order to optimize the radiolabelling of [18F]canagliflozin. Best results were obtained when the following protocol was used: 2.5‐
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3.0 mg (3.46‐4.16 μmol) of canagliflozin precursor in DMA (0.4 mL) was placed into a vial which contained Cu (OTf)2(py)4 (13.6 mg, 0.02 mmol) in DMA (0.4 mL) and Et4N·HCO3 (2.7 mg) in n‐BuOH (0.4 mL). The reaction mixture was heated at 150°C for 30 min. Deprotection of the acetyl groups was established with NaOH 1 M (1 mL) at 120°C for 5 min. The product was diluted with water (20 mL) and passed through a pre‐activated tC18 cartridge. The eluted product was then purified by HPLC and the collected peak of [18F]canagliflozin was further diluted with buffer for the ex vivo assays. Human kidney sections (8 μm) were incubated 1 hour with [18F] canagliflozin in the presence or absence of an excess of canagliflozin (Figure 1B). Results and Discussion Unfortunately direct substitution of 18F into canagliflozin by means of an isotope exchange reaction led to deterioration of the product due to the high temperatures needed for this transformation. In 2014 Gouverneur et al (Angew Chem, 2014, 7751) reported the production of 18F‐arenes from pinacol derived aryl boronic esters (arylBPin) upon treatment with [18F]KF/K222 and [Cu (OTf)2(py)4] (OTf = trifluoromethanesulfonate, py = pyridine). This method tolerates electron‐poor and electron‐ rich arenes and various functional groups. Therefore, it
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was decided to introduce the 18F label via a pinacol aryl boronic ester precursor. For the optimization of [18F] canagliflozin radiolabelling, the solvent was varied from DMA (dimethylacetamide) to DMSO and DMF. By using DMSO and DMF lower yields (2.5% for DMSO) and (0% for DMF) were obtained when compared to DMA under the same conditions. Better yields were obtained when the temperature was increased from 120°C (20% yield) to 150°C (37% yield) with DMA as a solvent. The product was obtained in a radiochemical yield of 37% (decay corrected from [18F]fluoride at the beginning of the synthesis) and a radiochemical purity >95%. The autoradiography clearly shows [18F]canagliflozin uptake (22% of added dose) in kidney sections. In the presence of excess canagliflozin, the uptake was reduced to 12%, suggesting selective binding of the tracer to SGLT‐2 transporters. Conclusion We have developed a production method for [18F] canagliflozin which have shown selectivity for SGLT‐2 transporters. This method is currently translated into a GMP compliance automated cassette‐based synthesis module for future use in patients. Figure 1 A) Scheme of the synthesis of [18F]canagliflozin. B) Autoradiography of human kidney sections incubated with [18F]canagliflozin 1. Cefalu, William T., et al. “Efficacy and safety of canagliflozin versus glimepiride in patients with type 2 diabetes inadequately controlled with metformin (CANTATA‐SU): 52 week results from a randomised, double‐ blind, phase 3 non‐inferiority trial.” The Lancet 382.9896 (2013): 941‐950. 2. Sha, S., et al. “Canagliflozin, a novel inhibitor of sodium glucose co‐transporter 2, dose dependently reduces calculated renal threshold for glucose excretion and increases urinary glucose excretion in healthy subjects.” Diabetes, Obesity and Metabolism 13.7 (2011): 669‐672.
M u l t i m o d a l i t y im a g i n g p ro b e s / n a n o p a r t i c l e s O-13 | Magnetic nanotheranostics enhances Cherenkov radiation–induced photodynamic therapy Dalong Ni1; Dawei Jiang1; Weijun Wei2; Lei Kang3; Jonathan Engle4; Weibo Cai1 1
University of Wisconsin‐Madison, USA; 2 Shanghai Jiao Tong University
Affiliated Sixth People's Hospital, China; 3 Peking University First Hospital, China; 4 Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
Objectives Photodynamic therapy (PDT) has been widely used in fundamental research and clinical practice. However, tissue
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penetration limitation, light dependence, and low tumor uptake of photosensitizers still remain major challenges for traditional nanoparticulate PDT. The interaction between radionuclides and nanomaterials could generate Cherenkov radiation (CR) and has provoked an emerging field that utilized such interaction for CR‐induced PDT, which could overcome the disadvantages of traditional PDT. However, such CR interaction is not strong enough, leaving clinicians uncertain of the benefit of this novel PDT method. Our goal is to develop a novel strategy to amplify the therapeutic effect of CR‐induced PDT. Methods Herein, we applied magnetic vectors to greatly enhance the effects of CR‐induced PDT under an external magnetic field, which provides a major step forward in photodynamic therapy. The magnetic nanoparticles (MNPs), namely, (Zn0.4Mn0.6)Fe2O4 nanoparticles, with 89Zr radiolabeling and porphyrin molecules (TCPP) surface modification (89Zr‐MNPs/TCPP) were developed for CR‐ induced PDT with magnetic targeting tumor delivery. The labeled 89Zr on the surface of MNPs could be used for PET imaging to investigate in vivo behavior of MNPs and intrinsically excited TCPP for singlet oxygen‐mediated destruction of tumor cells without any requirement of external excitation. We investigated magnetic‐targeted CR‐induced PDT using bilateral 4T1 tumor‐bearing mice with a magnet being applied on the right tumor side for 3 h after intravenous injection of 89Zr‐MNP/TCPP. Results These MNPs were uniform with an average diameter of about 20 nm and showed high saturation magnetization with no hysteresis, rendering these MNPs highly sensitive to the external applied magnetic field. After PEGlyation, the radionuclide 89Zr was chelator‐free radiolabeled with MNP‐PEG and relatively high labeling yields were achieved after incubation at 75°C (about 60%). PET images of normal mice showed the 89Zr‐MNP‐PEG with a long circulation half‐life of 2.46 h and mainly accumulated in the liver and spleen within two weeks after injection. Importantly, PET imaging of bilateral 4T1 tumor‐ bearing mice showed that the magnetic field (MF)‐ targeted tumors exhibited higher accumulation of 89Zr‐ MNP‐PEG (15.2 ± 4.8%ID/g at 3 h p.i.), which was fivefold higher than that of nontargeted tumors. After conjugating TCPP on the surface of MNP‐PEG (i.e., 89Zr‐MNP/ TCPP), the lasting generation of singlet oxygen (1O2) was found within one day, which also depended on the used dosage of radioactivity. The relative viabilities of the 4T1 cells incubated with89Zr‐MNP/TCPP decreased remarkably at higher radioactivity levels, indicating the therapeutic effect of CR‐induced PDT, which was confirmed by ROS staining under confocal imaging. For in vivo studies, the MF‐treated group, tumor growth of
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mice that received 89Zr‐MNP/TCPP treatment was significantly inhibited, whereas the MNP/TCPP‐treated group demonstrated rapid tumor growth. In contrast, the non‐MF targeted group showed lower tumor growth inhibition rates. The whole process was further verified by fluorescence, Cherenkov luminescence, and Cherenkov resonance energy transfer imaging of tumors. Conclusions By overcoming the depth and light dependence of traditional PDT, our findings revealed that 89Zr‐MNP/TCPP
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nanostructures exhibited efficient singlet oxygen generation. Importantly, magnetism‐targeted and enhanced CR‐induced PDT has been demonstrated on bilateral 4T1 tumor‐bearing mice, with rapid and significant inhibition of tumor growth in vivo under the external magnetic field. These magnetic nanostructures also displayed excellent magnetic targeting fluorescence, Cherenkov luminescence, and Cherenkov resonance energy transfer imaging to monitor the therapeutic effects of tumors. Overall, the strategy described herein
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is versatile and has great promise as an advanced phototherapy tool for treating a variety of lesions in clinics.
M u l t i m o d a l i t y im a g i n g p ro b e s / n a n o p a r t i c l e s
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second imaging and biodistribution study, tumor targeting properties were compared among all twelve ligands (2 h p.i., 0.3 nmol, 10 MBq/mouse). Additionally, co‐localization studies comparing 111In autoradiography, IRDye700DX fluorescence, and PSMA immunohistochemistry were performed. Name Ligand
Chemical Structure*
PSMA‐025
PSMA‐linker‐D‐Phe‐DOTAGA
PSMA‐046
PSMA‐linker‐D‐Phe‐IRDye700DX‐DOTAGA
PSMA‐057b
PSMA‐linker(2‐)‐D‐Phe‐DOTAGA
PSMA‐064
PSMA‐linker(2‐)‐D‐Phe‐IRDye700DX‐DOTAGA
PSMA‐J26
PSMA‐linker(2‐)‐D‐Phe‐IRDye700DX‐linker(n)‐ DOTAGA
PSMA‐J27
PSMA‐linker(2‐)‐D‐Phe‐IRDye700DX‐linker(n)‐ DOTA
Netherlands
PSMA‐111
PSMA‐linker(2‐)‐D‐Phe‐linker(n)‐IRDye700DX‐ DOTAGA
Objectives Incomplete resection of prostate cancer (PCa) and its metastases may lead to disease recurrence and consequently poor patient outcome. To obtain complete resection of tumor tissue, prostate‐specific membrane antigen (PSMA) targeting bimodal ligands containing both a radiolabel and a photosensitizer can be used for intra‐ operative tumor detection, accurate tumor delineation, and tumor‐targeted photodynamic therapy (tPDT); a selective cancer treatment that induces cell destruction upon exposure to near‐infrared (NIR) light. The aim of our study was to synthesize and evaluate bimodal (GA)‐IRDye700DX‐PSMA PSMA‐ [111In]In‐DOTA targeting agents for intra‐operative detection and treatment of PSMA‐positive tumor lesions. Methods Twelve glutamate‐urea‐lysine‐based PSMA ligands, varying in their linker and chelator moieties, were synthesized and conjugated with DOTAGA or DOTA and IRDye700DX (Table 1). After 111In‐labeling, PSMA binding and internalization capacity in PSMA‐transfected LS174T and PSMA‐negative wild‐type LS174T cells were determined in vitro. Additionally, cell viability of LS174T‐PSMA‐positive and negative cells was analyzed after tPDT with 300 J/cm2 near infrared (NIR) light irradiation. To determine the optimal ligand dose and timing for in vivo imaging and tPDT, BALB/c nude mice with both s.c. LS174T PSMA‐positive and ‐negative tumors were injected with 111In‐PSMA‐064 (0.1‐3 nmol, 10 MBq/mouse). At 1, 2, 4, and 24 h p.i., accumulation of the tracer in the tumor was evaluated using microSPECT/CT and NIR fluorescence imaging, and biodistribution was determined after dissection. In a
PSMA‐122
PSMA‐linker(2‐)‐D‐Phe‐IRDye700DX‐linker(1‐)‐ DOTA
PSMA‐140
PSMA‐linker(3‐)‐D‐Phe‐IRDye700DX‐DOTA
PSMA‐142
PSMA‐linker(3‐)‐D‐Phe‐IRDye700DX‐DOTAGA
PSMA‐143
PSMA‐linker(3‐)‐IRDye700DX‐DOTAGA
PSMA‐144
PSMA‐linker(2‐)‐IRDye700DX‐DOTAGA
O-14 | Bimodal PSMA ligands for intra‐operative tumor detection and targeted photodynamic therapy of PSMA‐expressing tumors Yvonne Derks1; Helene Amatdjais2; Jaw Malekzad2; Gerben Franssen1; Annemarie Kip1; Dennis Lowik2; Otto Boerman1; Mark Rijpkema1; Peter Laverman1; Susanne Lutje1; Sandra Heskamp1 1
Radboud University Medical Center, Netherlands; 2 Radboud University,
Results All bimodal ligands showed specific binding to PSMA‐ expressing LS174T cells in vitro. Enhanced internalization of IRDye700DX‐coupled ligands was observed compared to non‐fluorescent controls (90.8% ± 5.4% vs. 59.2% ± 2.3%, respectively). Viability of tPDT‐treated LS174T‐PSMA cells was reduced with 87.6% ± 5.8% (P < 0.001). In vivo, highest tumor uptake in s.c. LS174T‐ PSMA tumors was measured 2 h p.i. at a dose of 0.3 nmol/mouse (12.6 ± 1.8 %ID/g), which was significantly higher than uptake in PSMA‐negative LS174T tumors (0.5 ± 0.1 %ID/g, P < 0.001). Tumors were clearly visualized with both microSPECT/CT and NIR fluorescence imaging. Accumulation of the twelve [111In]In‐ DOTA (GA)‐IRDye700DX‐PSMA ligands in LS174T‐ PSMA tumors ranged from 5.3 ± 0.7 %ID/g (111In‐PSMA‐ 046) to 15.1 ± 0.8 %ID/g (111In‐PSMA‐064) and was significantly higher as compared to uptake in PSMA‐negative LS174T tumors for all ligands (average 0.4 ± 0.2 %ID/g, P < 0.001). Addition of the 2 or 3 extra negative charges in the linker part of the ligand and conjugation of the IRDye700DX moiety improved accumulation in the PSMA‐positive tumors. Moreover, analysis of LS174T‐ PSMA tumors sections demonstrated co‐localization of the radioactive signal, fluorescent signal and PSMA expression as determined immunohistochemically.
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FIGURE 1 MicroSPECT/CT, NIR fluorescent imaging, and biodistribution after dissection of [111In]In‐DOTA (GA)‐ IRDye700DX‐PSMA bimodal ligands in BALB/C nude mice. (A) MicroSPECT/CT and (B) IRDye700DX NIR fluorescent imaging of [111In]In‐DOTAGA‐ IRDye700DX‐PSMA ligands, 0.3 nmol, 10 MBq/mouse, 2 h p.i. in BALB/c nude mice with subcutaneous PSMA‐expressing LS174T‐PSMA (left flank) and PSMA‐ negative LS174T (right flank) tumors. (C) Biodistribution after dissection of the twelve bimodal ligands (0.3 nmol, 10 MBq/mouse, 2 h p.i.)
Conclusions Here, we demonstrate highly efficient and PSMA‐ specific uptake of newly developed [111In]In‐DOTA (GA)‐IRDye700DX‐PSMA PSMA‐targeting ligands. Furthermore, the feasibility of bimodal ligand‐mediated tPDT on PSMA‐positive cells was demonstrated in vitro. Interestingly, the IRDye700DX and negative charges in close proximity to the PSMA‐binding motif were shown to improve tumor targeting of the ligands. Consequently, 111In‐PSMA‐064, ‐142 and ‐143 are the most promising bimodal ligands. In the future, these ligands will be used for intra‐operative tumor detection to improve the surgical outcome of PCa patients. ACKNOWLEDGEMENT This work was supported by EKFS (2016‐A64) and the Dutch Cancer Society (NKB‐KWF 10443/2016‐1).
M u l t i m o d a l i t y im a g i n g p ro b e s / n a n o p a r t i c l e s O-15 | Evaluation of N‐alkylaminoferrocenes for in‐vivo imaging of reactive oxygen species activity using PET and optical imaging Johannes Toms1; Simone Maschauer1; Steffen Daum2; Viktor Reshetnikov2; Andriy Mokhir2; Olaf Prante1
1
Department of Nuclear Medicine, Molecular Imaging and Radiochemistry,
Friedrich‐Alexander University Erlangen‐Nürnberg (FAU), Germany; 2
Department of Chemistry and Pharmacy, Organic Chemistry II, Friedrich‐
Alexander University Erlangen‐Nürnberg (FAU), Germany
Objectives Many tumor cells show intracellular increased concentrations of reactive oxygen species (ROS), which can be used for prodrug activation. N‐Alkylaminoferrocenes are ROS‐ dependent prodrugs and were successfully tested in vitro as therapeutic cancer agents.1 Their biodistribution and suitability for ROS imaging was evaluated in this study. Methods The Cu(I)‐catalyzed alkyne‐azide‐cycloaddition (CuAAC) with 6‐deoxy‐6‐[18F]fluoroglycosyl azide was applied to the 18F‐labeling of an N‐alkinylaminoferrocene glycoconjugate. After optimization of the reaction conditions and HPLC purification of the radiotracer [18F]1 (Figure 1), various in vitro studies were performed (uptake in PC‐3 and AR42J tumor cells, stability in serum, logD value). The in vivo biodistribution was evaluated by μPET (Inveon, Siemens) using PC‐3 and AR42J tumor‐bearing nude mice. In addition, optical imaging experiments (IVIS, PerkinElmer) for further characterization of the ROS content of tumors were performed by the use of a chemoluminescent luminol‐based probe (L‐012).
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The biodistribution of the N‐alkylaminoferrocene at 1, 3, 5, and 24 h p.i. was further studied by fluorescence imaging using a Cy5‐labeled N‐alkylaminoferrocene. Results [18F]1 was synthesized in a radiochemical yield of 85% as determined on HPLC under optimized reaction conditions (Cu (OAc)2, THPTA, sodium ascorbate, 200 nmol alkyne, 40 nmol carrier (boronic acid pinacol ester of 1), phosphate buffer/THF (12/5), Vtotal = 850 μL, 15 min, 60°C). [18F]1 was found to be in a redox equilibrium with its oxidized form [18F]1+. By addition of carrier, the equilibrium could be shifted to [18F]1, which is supposed to show superior cell membrane permeability. A stable formulation of non‐oxidized [18F]1 by addition of sodium ascorbate remained difficult to prepare. The analysis of a sample of [18F]1 in human serum showed 11% of intact tracer after 35 min at 37°C and radiometabolites. The uptake of [18F]1 in PC‐3 and AR42J tumor cells was 4‐8 %/mg after 120 min at 37°C. The log D value was determined to be 0.84 ± 0.04. Using chemoluminescence imaging after injection of L‐012 into mice, higher ROS concentration was detected in PC‐3 tumors when compared with AR42J tumors, being in agreement with in vitro assays on the ROS concentration of the cell lines. After i.v. injection of [18F]1 in tumor‐bearing mice, the uptake of the tumor at 50 min p.i. was 0.8 %ID/g (PC3) and 1.1 %ID/g (AR42J), which was 2‐3‐fold higher when compared to background values, as determined by small animal PET. Finally, the biodistribution of a Cy5‐labeled N‐ alkylaminoferrocene as an analog of 1 was analyzed for later time points of injection by in vivo fluorescence imaging of mice and ROS‐specific uptake was demonstrated by ex vivo imaging 24 h p.i. of tissues of interest. Conclusion The 18F‐fluoroglycosylated N‐alkylaminoferrocene [18F]1 showed low stability in vitro; however, specific uptake in ROS‐rich tumors was shown in vivo by PET at 50 min p.i. Optical imaging experiments with a Cy5‐conjugated N‐
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alkylaminoferrocene gave valuable insight into the biodistribution at later time points after injection. Therefore, these results on PET together with optical imaging could facilitate the application of N‐alkylaminoferrocenes as therapeutic anti‐cancer agents. RE FER EN CES 1. Marzenell P, Hagen H, Sellner L, Zenz T, Grinyte R, Pavlov V, Daum S, Mokhir A. J. Med. Chem. 2013, 56, 6935‐6944.
Mul ti mo d a l i ty i ma g i n g p r ob es / n an op ar t i c l es O-16 | A Cell surface thiol targeting dual PET and fluorescent labelling reagent for multi‐ scale cell tracking Truc Pham; Ran Yan; John Maher King's College London, UK
Background Emerging as the fourth pillar of health care, cell‐based immunotherapies offer a novel and rapidly developing technology that has great potential to ameliorate human disease. One fundamental challenge in the successful development and clinical application of cellular therapeutics is the need to better understand the in vivo behaviour of adoptively infused cell products.1 We envisage that a dual PET and fluorescent cell labelling reagent will harness the synergistic property of both imaging modalities to visualise the labelled cells across cellular to whole body scales. By placing the dual imaging reagent extracellularly, the cytotoxicity and radiation damages to the cells would be minimised. Methods We synthesized a new dual‐modality trifunctional labelling reagent, 124I‐Green‐maleimide using a one‐pot three
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component radioiodination chemistry.2 It equips with: (i) a long half‐life positron emitter, iodine‐124 (t1/2 = 4.2 days) for macro‐scale cell tracking with PET; (ii) a clinically approved green fluorescent reporter, fluorescein, for micro‐scale fluorescence cell imaging; (iii) a maleimide moiety, for cell membrane thiol coupling (Figure 1A). The cellular distribution of the dual labelling reagent, its radiolabelling efficiency, and radiolabel retention were evaluated on murine multiple myeloma 5T33 and Jurkat cells, respectively, in vitro. The in vivo migration of the dual labelled Jurkat cells was also investigated using sequential PET imaging in NSG mice. Results The 124I‐Green‐maleimide was prepared with radiochemical yields (RCYs) of 80.5 ± 5.5% (n = 2) measured by HPLC and its isolated RCYs were 60.3 ± 5.8% (n = 2) with the molar activity around 1.87 GBq/μmol. The
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confocal images revealed the cell surface localisation of the 124I‐Green‐maleimide on both 5T33 and Jurkat cells (Figure 1B). The radiolabelling efficiency of 5T33 and Jurkat cells (10 × 106) with the 124I‐Green‐ maleimide were 24.2 ± 2.1% and 26.1 ± 1.0% (n = 3), respectively. Notably, about 18% and 22% of total radioactivity still retained in 5T33 and Jurkat cells, respectively, 7 days post labelling without apparent impact on their viability and reproducibility. When 124I‐Green‐ maleimide dual labelled Jurkat cells (2 × 106) were intravenously injected to NSG mice, the radioactivity was mainly accumulated in the lung of the animals at 24 and 48 h post injection (Figure 1C). Figure 1: A) 124I‐ Green‐maleimide targeting the surface protein thiols; B) confocal image of 124I‐Green‐maleimide labelled 5T33 cells. Nuclei were stained with Hoechst33342; C) PET/CT images of the dual labelled Jurkat cells
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(2 × 106) at 24 and 48 h post intravenously injection in NSG mice. Conclusions A dual PET and fluorescent cell labelling reagent, 124I‐ Green‐maleimide, was prepared in excellent RCYs. It labelled various cell lines through their membrane thiols with good labelling efficiency and prolonged radiolabel retention. The in vivo distribution of the dual labelled Jurkat cells was visualised with PET imaging. These promising results warrant future labelling of the therapeutic CAT T‐cells with the 124I‐Green‐maleimide for both in vivo PET and ex vivo fluorescence tracking study. ACKNOWLEDGEMENT Truc Pham would like to thank Rosetrees Trust PhD studentship (M585) for supporting this work. R EF E RE N C E S 1. Kircher CF, Gambhir SS, Grimm J. Nat Rev Clin Oncol. 2011, 8, 677‐688 2. Yan R, et al. J Am Chem Soc. 2013, 135, 703‐709
Radiochemistry ‐ radiometals O-17 | Towards cancer theranostics: 68Ga‐, 44g
Sc‐, 177Lu‐, and derivatives
225
Ac‐labeled bombesin
Simon Ferguson1; Melinda Wuest1; Cody Bergman1; Nikki Thiele2; Susan Richter1; Hans‐Sonke Jans1; Valery Radchenko3; Patrick Causey4; Randy Perron4; Paul Schaffer3; Justin Wilson2; Terence Riauka1; Frank Wuest1 1
University of Alberta, Canada; 2 Cornell University, USA; 3 TRIUMF,
Canada; 4 Canadian Nuclear Laboratories (CNL), Canada
with respect to ligand concentration and reaction conditions. Results [68Ga]Ga‐DOTA‐BBN2 and [44gSc]Sc‐DOTA‐BBN2 were prepared in radiochemical yields of 64 ± 16% and 80 ± 3%, respectively. PET imaging revealed the following tumor uptake values: [68Ga]Ga‐DOTA‐BBN2 (SUV60min (MCF‐7) 0.25 ± 0.03, SUV60min (PC3) 0.51 ± 0.06); [44gSc]Sc‐DOTA‐BBN2 (SUV60min (MCF‐7) 0.20 ± 0.03, SUV60min (PC3) 0.32 ± 0.03). Greater than 99% incorporation of 177Lu and 225Ac with DOTA‐BBN2 was achieved at concentrations of 10−5 M and 10−4 M, respectively, at 60 min and 85°C. Greater than 99% incorporation of 225Ac into macropa‐BBN2 was achieved at room temperature at 10−5 M concentration, which represents a ten‐fold decrease in the ligand concentration with respect to DOTA‐BBN2. Conclusions PET imaging revealed higher uptake of 68Ga‐ and 44gSc‐ labeled peptides in PC3 tumors compared to MCF‐7 tumors with overall higher tumor uptake values for [68Ga]Ga‐DOTA‐BBN2 compared to [44gSc]Sc‐DOTA‐ BBN2. Radiolabeling of 68Ga, 44gSc, and 177Lu was highly successful with DOTA, whereas 225Ac radiolabeling proceeded best with macrocycle macropa, confirming the reported superior complexation properties of the 18‐membered macrocyclic ligand for 225Ac2. ACKNOWLEDGEMENTS The authors gratefully acknowledge the Dianne and Irving Kipnes Foundation and the National Science and Engineering Research Council of Canada (NSERC) and Alberta Innovates Health Solutions for supporting this work. RE FER EN CES 1. Richter S, et al. Mol. Pharm. 2016, 13, 1347‐57.
Objectives Gastrin releasing peptide receptors (GRPRs) are overexpressed in many breast and prostate cancers. Herein, we describe radiolabeling of metabolically stabilized bombesin derivatives (DOTA‐BBN2 and macropa‐ BBN2) with radiometals for PET imaging (68Ga, 44gSc) and radiotherapy (177Lu, 225Ac). 68Ga and 44gSc‐labeled DOTA‐BBN2 were used for PET imaging experiments in preclinical breast (MCF‐7) and prostate (PC3) cancer models with high baseline expression of GRPRs. Methods DOTA‐BBN2 and marcopa‐BBN2 were synthesized according to literature procedures1,2. Dynamic PET imaging of [68Ga]Ga‐DOTA‐BBN2 and [44gSc]Sc‐DOTA‐ BBN2 was performed in MCF‐7 and PC3 tumor‐bearing mice. Radiolabeling of DOTA‐ and macropa‐decorated BBN2 with 177Lu and 225Ac, respectively, was optimized
2. Thiele N. A. et al. Angew. Chem. Int. Ed. Engl. 2017, 56, 14712‐17.
R a d i o ch e m i s t r y ‐ r a d i o m e t a l s O-18 | Synthesis and comparison of novel fusarinine C‐based chelators for
89
Zr‐labeling
Chuangyan Zhai1; Shanzhen He2; Xuebing Chen3; Jiancong Lu3; Christine Rangger4; Dominik Summer; Hubertus Haas5; Julie Foster6; Jane Sosabowski7; Clemens Decristoforo8 1
Southern Medical University, China; 2 Department of Nuclear Medicine,
Guangdong General Hospital, China; 3 School of Forensic Medicine, Southern Medical University, China; 4 Department of Nuclear Medicine, Medical University Innsbruck, Austria; 5 Division of Molecular Biology, Biocenter, Medical University Innsbruck, Austria; 6 Centre for Molecular
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Oncology, Barts Cancer Institute, Queen Mary University of London, UK; 7
Centre for Molecular Oncology and Imaging, UK; 8 Medical University
Innsbruck, Austria
Objective Fusarinine C (FSC) recently demonstrated promising prospects as a novel 89Zr‐chelator.1 Here, FSC was further derivatized to optimize the complexation properties of FSC‐based chelators for 89Zr‐labeling by introducing additional carboxylic acid groups. These were expected to improve the stability of 89Zr‐complexes by saturating the 8 coordination sphere of [89Zr]Zr4+ and also to introduce functionalities suitable for conjugation to targeting vectors such as monoclonal antibodies. Methods FSC (succ)2AA and FSC (succ)3 were synthesized by reacting the amine groups of FSC with succinic anhydride (succ) or acetic anhydride (AA). 89Zr‐labeling of FSC (succ)2AA and FSC (succ)3 were performed as we reported previously. For in vitro evaluation, partition coefficients, protein binding properties, and serum stability as well as acid dissociation and transchelation studies of 89Zr‐complexes were evaluated and compared with 89 Zr‐desferrioxamine B ([89Zr]Zr‐DFO) and 89Zr‐ triacetylfusarinine C ([89Zr]Zr‐TAFC). The in vivo properties of [89Zr]Zr‐FSC (succ)3 were further compared with [89Zr]Zr‐TAFC in BALB/c mice using microPET/CT imaging. Results FSC (succ)2AA and FSC (succ)3 were synthesized with satisfactory yield. Quantitative 89Zr‐labeling of FSC (succ)2AA and FSC (succ)3 was achieved in HEPES buffer at RT between pH 6.8 to 7.2 within 90 min. Distribution coefficients of 89Zr‐complexes revealed increased hydrophilic characters as compared to [89Zr]Zr‐TAFC. All radioligands showed high stability in PBS and human serum and low protein‐bound activity over a period of 7 days. Acid dissociation and transchelation studies exhibited different in vitro stabilities following the order: [89Zr]Zr‐FSC (succ)3 > [89Zr]Zr‐TAFC > [89Zr]Zr‐FSC (succ)2AA >> [89Zr]Zr‐DFO. Biodistribution studies of [89Zr]Zr‐FSC (succ)3 revealed a slower excretion pattern as compared to [89Zr]Zr‐TAFC. No visible bone uptake was observed from microPET/CT images at 24 h p.i. demonstrating the in vivo stability of [89Zr]Zr‐FSC (succ)3. Conclusion [89Zr]Zr‐FSC (succ)3 showed best stability and inertness and [89Zr]Zr‐FSC (succ)2AA predicts the potential of FSC (succ)2 as a monovalent chelator for conjugation to targeted biomolecules in particular monoclonal antibodies. ACKNOWLEDGEMENTS We acknowledge the financial support of the National Natural Science Foundation of China (NSFC) grants 81701738
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and 81871418, Austrian Science Foundation (FWF) grants P 25899‐B23 and I 1346, and Natural Science Foundation of Guangdong Province (project no. 2017A030310526). RE FER EN CE 1. Zhai C, Summer D, Rangger C, Franssen G, Laverman P, Haas H, Petrik M, Haubner R, Decristoforo C. Novel bifunctional cyclic chelator for 89Zr labeling‐radiolabeling and targeting properties of RGD conjugates [J]. Molecular Pharmaceutics, 2015, 12(6): 2142–2150.
R a d i o ch e m i s t r y ‐ r a d i o m e t a l s O-19 | New bifunctional chelators for theranostic applications Lee Lee Li1; Maria de Guadalupe Jaraquemada‐Pelaez2; Nicole Sarden2; Hsiou‐Ting Kuo3; Eduardo Aluicio Sarduy4; Andrew Robertson5; Thomas Kostelnik2; Una Jermilova2; Emily Ehlerding4; Helen Merkens6; Katrin Gitschtaler6; Valery Radchenko7; Kuo‐Shyan Lin3; Francois Benard3; Jonathan Engle4; Paul Schaffer7; Chris Orvig1 1
The University of British Columbia, Canada; 2 Medicinal Inorganic
Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, BC, Canada; 3 BC Cancer Research Centre, Canada; 4
Department of Medical Physics, University of Wisconsin School of
Medicine and Public Health, Madison, WI, USA; 5 Life Sciences Division, TRIUMF, Vancouver, BC, Canada; 6 Department of Molecular Oncology, BC Cancer Agency, Vancouver, BC, Canada; 7 TRIUMF, Canada
Objectives Technological advancements in radionuclide production and engineering bio‐targeting vectors both contribute to the rapidly growing metallo‐radiopharmaceutical field. One key to non‐invasive delivery of radioactive dose to the targeting site (i.e. tumor for oncology purposes) is a biologically stable, easily radiolabeled, functionally versatile chelator. DOTA has become a widely used chelator for radiometal conjugation. However, in most cases, it requires heating and relatively high concentrations of conjugated precursor to achieve high radiolabeling efficiency. Our group has developed a library of acyclic chelators that allow fast complexation with high complex stability. Most promising examples are H4octapa (N4O4), H4pypa (N5O4), and H4py4pa (N7O4). These ligands have potential coordination numbers ranging from 8 to 11, resulting in favorable chelation with a range of diagnostic and/or therapeutic radioisotopes. The foci in this work are 111In (t1/2 = 2.80d, EC), 44Sc (t1/2 = 3.97h, b +), 177Lu (t1/2 = 6.65d, b‐), and 225Ac (t1/2 = 9.92d, a). All three chelators have at least one bifunctional analog, and
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all have been conjugated to monoclonal antibody Trastuzumab (anti‐HER2) while H4octapa and H4pypa have also been coupled to a Glu‐urea‐Lys based PSMA (prostate specific membrane antigen) targeting peptidomimetic. The synthesis and characterization of the chelators and the bifunctional analogs, will be discussed, along with the results from radiochemical and in vivo studies. Methods All synthesized chelators were characterized by 1H and 13 1 C{ H} NMR spectrometry, high‐resolution mass spectrometry and elemental analysis. Complexation with
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non‐radioactive metal salts were performed with H4pypa (In, Lu, Sc, La) and H4py4pa (La) and the complexes were studied with 1H, 13C{1H}, 13C{1H}‐1H HSQC and COSY NMR spectrometry, while the crystal structure of [natLu (Hpypa)] was characterized. Thermodynamic stability constants and pM values were determined for [M (pypa)]‐ complexes (M = Sc, In, Lu, Y, La) by potentiometric titration and UV‐vis spectrophotometry. Radiolabeling of [AE] [E (pypa)]‐ (AE = 111In, 177Lu, 44 Sc, 225Ac), [225Ac][Ac (octapa)]‐, [225Ac][Ac (py4pa)]‐ were performed, and the radiochemical yields were analyzed by iTLC and/or rHPLC. In vitro stability was
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determined by human/mouse serum challenge and the percentage of intact complex was analyzed by iTLC. Binding assays and biodistribution studies were performed with the PSMA‐positive PC3‐pip or LNCaP cell lines. Results First of all, the synthesized H4pypa‐C7‐PSMA617 showed quantitative radiochemical yield (RCY > 98%) with 111In and 177Lu at ligand concentrations as low as 10−6 M and 10−7 M (pH = 7, 15 minutes, RT), respectively, which were comparable to those of H4pypa, implying that the targeting moiety did not impede the coordination. Animal studies are currently in progress. The PSMA‐ targeting conjugate also demonstrated promising chelation with 44Sc (pH = 4.5, 30 minutes, RT), showing specific tumor (PSMA+) uptake (4.86 %ID/g from ex vivo biodistribution, 8 h p.i.) without significant off‐target uptake, except in the kidney. The overall results highlight the potential theranostic applications of H4pypa. As for 225 Ac chelation, three chelators (H4octapa, H4pypa and H4py4pa) were compared with DOTA for 225Ac radiolabeling. After 30 minutes at RT, H4py4pa and H4octapa showed the most promising radiolabeling results (RCY = 98%, at 10−6 M ligand concentration), while H4pypa required 10‐fold higher concentration for 93% RCY. Nonetheless, the results obtained were significantly better for the three chelators than for DOTA. All chelators have been conjugated to monoclonal antibody Trastuzumab, and radiolabeling and serum stability studies are in progress. Conclusions Preliminary radiolabeling and in vitro stability data have proven the potential theranostic applications of [AE] [E (pypa)] (AE = 111In, 177Lu, 44Sc, 225Ac). Additionally, pypa can be easily bifunctionalized and the corresponding radiolabeled PSMA‐targeting peptidomimetic conjugates are being studied. Moreover, the affinities of H4octapa, H4pypa and H4py4pa to 225Ac were compared and the radiolabeling data were highly encouraging. Radiolabeled Trastuzumab conjugates are currently being investigated. ACKNOWLEDGEMENTS We thank NSERC CREATE IsoSiM at TRIUMF for funding a PhD research stipend (LL) and both NSERC and CIHR for financial support via a Collaborative Health Research Project (CHRP to FB, CO and PS). TRIUMF receives additional funding via a contribution agreement with the National Research Council of Canada.
R EF E RE N C E J Am Chem Soc. 2013;135, 12707‐12721 Kostelnik TI, Orvig C. Chem. Rev. https://doi.org/10.1021/acs.chemrev.8b00294
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R a d i o ch e m i s t r y ‐ r a d i o m e t a l s O-20 | Cooperative capture synthesis for the development of novel supramolecular radiotracers Faustine d'Orchymont; Jason Holland Department of Chemistry, University of Zurich, Switzerland
Objectives Supramolecular chemistry involves systems held together by non‐covalent interactions, considerably weaker than covalent bonds. In the recent years, these systems have been largely studied as targeted drug‐delivery systems. Supramolecular host molecules such as β‐cyclodextrins (β‐CD) and cucurbituril (CB[6]) have shown great potential in drug design due to excellent biocompatibility and their ability to trap molecules through molecular recognition in their unique hydrophobic cavities. In particular, the cavity of CB[6] catalyses alkyne‐azide cycloadditions (CB‐AAC) in an ideal stoichiometric ratio for the syntheses of mechanically interlocked molecules (MIMs), such as rotaxanes. Addition of β‐CD, which contains hydrogen‐bonding donors, was found to accelerate the CB‐AAC reaction. Using this unique ability of CB[6] and β‐CD, we aim to develop an efficient and modular synthetic tool for the synthesis of unprecedented non‐ covalently bound radiotracers, and to explore supramolecular interactions in radiochemistry. Methods Desferrioxamine B azide (DFO‐azide) was prepared by amine coupling through standard NHS/EDC chemistry. The CB‐AAC reaction occurs between the terminal azide group of DFO‐azide and the alkyne groups of the biphenyl unit (guest‐alkyne). The rotaxane was successfully obtained by a one‐pot reaction strategy involving cooperative capture synthesis and molecular recognition. This quick rotaxane formation is explained by an efficient preorganisation through a hydrogen bonding network and host‐guest complex formation between the substrates. The crude rotaxane was purified by semi‐ preparative HPLC. Radiolabelling was achieved by addition of an aliquot of [68Ga][Ga(H2O)6]Cl3(aq.) stock solution to an aqueous solution of the rotaxane buffered with NaOAc (0.2 M, pH 4.4). The reaction was monitored by using a radio‐iTLC and the product was characterised by analytical HPLC. Results The rotaxane was synthesised within one minute in H2O by mixing DFO‐azide, CB[6], guest‐alkyne and β‐CD in a 2:2:1:1 ratio at 80°C (Figere 1A). Reactions were monitored by 1H‐NMR. 68Ga‐radiolabelling reaction was
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(A) Reaction scheme and structure of [68Ga]Rotaxane. (B) Reverse‐phase HPLC chromatograms of (top, blue) the radioactive [ Ga]Rotaxane, and (bottom, black) co‐injection of the non‐radioactive natGa‐Rotaxane, l = 254 nm. (*) mono 68Ga/natGa rotaxane, 5%.
FIGURE 1 68
complete after 10 min at 23°C giving a radiochemical conversion >99%. The identity of the radiolabelled compound [68Ga]Rotaxane was confirmed by co‐injection with an authenticated sample of natGa‐Rotaxane (Figure 1B, retention time: 7.12 min, radiochemical purity >95%). Conclusion We have put cooperative capture synthesis into practice by (i) demonstrating that CB‐AAC can accept a larger scope of substrates by introducing a chelate as one of the four components, (ii) synthesising a rotaxane within a minute in water by introducing β‐CD as a co‐catalyst, and (iii) successfully synthesising a non‐covalently bound supramolecular radiotracer in high radiochemical yield and purity. Studies are ongoing to exploit our supramolecular approach in the synthesis of targeted radiotracers based on peptides and proteins. ACKNOWLEDGEMENTS FdO thanks the Swiss Government excellence scholarship. J.P.H thanks the Swiss Cancer League (Krebsliga Schweiz; KLS‐4257‐08‐2017), the Swiss National Science Foundation (SNSF Professorship PP00P2_163683), the European Research Council (ERC‐StG‐2015, NanoSCAN – 676904), and the University of Zurich for financial support. R EF E RE N C E Hou X, Ke C, Stoddart JF. Chem. Soc. Rev., 2016, 45, 3766.
Radiochemistry ‐ radiometals O-21 | In vivo stable bisarylmercury bispidine as a tool for Hg‐197(m) applications Ian Moore Gilpin1; Martin Walther2; Jens Pietzsch3; Hans‐Jurgen Pietzsch2
1
HZDR, Germany; 2 Helmholtz‐Zentrum Dresden‐Rossendorf, Germany;
3
Department Radiopharmaceutical and Chemical Biology, Institute of
Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum Dresden‐ Rossendorf, Germany
Intro Reactor‐produced Hg‐197 saw previous medical use in radiolabelled chlormerodrin for SPECT imaging1 in the 1960s and 70s but was discontinued because of the up‐ and‐coming Tc‐99m generator system's widespread use, the uncertain in vivo stability of Hg‐197 labelled compounds and the low molar activity of the Hg‐197 itself (500 GBq/μmol),3 allowing access, at innocuous mercury concentrations, to the theranostically useful decay modes and half‐life of the radiometal's metastable nuclear isomer (γ for SPECT‐ imaging and conversion and auger electrons for tumour therapy. Hg‐197g T1/2 = 64.1 h, Hg‐197m T1/2 = 23.8 h). Objective The development of an in vivo stable mercury compound able to conjugate to a cancer‐targeting carrier. Radiopharmaceutical applications obviously require high in vivo stability but the fast metabolism of most mercury compounds in solution is a prevalent issue.4 However, Hg‐C organometallics show good water‐stability and bypass the issue of Hg‐S bonds suffering from competition by common thiol‐containing biomolecules, e.g., cysteine. Therefore, this project is specifically focussed on the strongest of this kind: the mercury‐phenyl bond.5 Previous study has shown that the syntheses of monodentate ligands for κ1‐L2Hg species suffer from significant cleavage.6 For this reason, our research is centred on the synthesis of a bidentate chelator design, due to the entropic
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advantage, the improved formation kinetics and the stability imparted by steric shielding. Current Results Separation from the gold target leaves the produced Hg‐ 197(m) in an acidic aqueous solution as the chloride salt. Consequently, transmetallation, via boronic acid or stannyl derivatives, was chosen as a feasible route for forming the mercury‐carbon bonds. Following several chelator attempts, all showing low selectivity for the 1:1‐ compound, a better fitting structure was found using the bispidine backbone (being known in co‐ordination chemistry for a variety of metals, good bio‐stability and its bridge linking‐functionalisation).7 After improvement of the reaction conditions, radiolabelling experiments showed good evidence of specific binding with the bispidine derivative 9‐butyl‐1,5‐diphenyl‐3,7‐bis(2‐ (trimethylstannyl)benzyl)‐3,7‐diazabicyclo[3.3.1]nonan‐9‐ ol “L1(SnMe3)2,” as analysed by thiol‐impregnated radio‐ TLC and supported by radio‐HPLC, whilst ESI‐MS of the stable mercury compound provided evidence that the desired 1:1 product had been formed. The in vitro stability tests conducted on the radiolabelled compound showed exciting results, with negligible degradation after 5 days (thereafter the activity was below analytical levels) in solutions with excess glutathione and 2,2′,2″‐nitrilotris (ethane‐1‐thiol). The only noticeable (ca. 5% degradation after 48 h), but expected reaction, was with sodium sulphide. Biodistribution experiments in healthy male Wistar rats showed no build‐up in the kidneys, with excretion occurring through the liver, indicating no de‐metallation. Summary The bisarylmercury bispidine (L1Hg) shows good stability in vitro as well as in vivo and is a promising candidate as a biocompatible mercury binding compound. Further
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research is continuing into full characterisation, conjugation to peptides and proteins, subsequent in vivo studies and for derivatives based on the structural design. ACKNOWLEDGEMENTS Regina Herrlich, Ulrike Gesche, Thomas Wünsche. Hg‐ 197(m) measurements were carried out at the CANAM infrastructure of the NPI CAS Rez supported through MEYS project no. LM2011019. RE FER EN CES 1. Sodee DB. Comparison of 99mTc‐pertechnetate and 197Hg‐ chlormerodrin for brain scanning. J Nucl Med 1968;9(12):645. 2. Ribeiro Guevara S, Zizek S, Repinc U, Perez CS, Jacimovic R, Horvat M. Anal Bioanal Chem 2007;387:2185–2197. 3. Walther M, Preusche S, Bartel S, Wunderlich G, Freudenberg R, Steinbach J, Pietzsch H‐J. Appl Radiat Isot 2015;97:177‐181. 4. Henke KR, Robertson D, Krepps MK, Atwood DA. Wat Res 2000;34:3005‐3013. 5. Dean JA. Lange's Handbook of Chemistry, 15th ed. McGraw‐Hill, Inc: 1998.606 p. 6. Wilhelm M, Saak W, Strasdeit H. Z Naturforsch 2000;55b:35‐38. 7. Comba P, Haaf C, Wadepohl H. Inorg Chem 2009;48:6604‐6614.
R a d i o ch e m i s t r y ‐ r a d i o m e t a l s O-22 | Positron emission tomography imaging of adeno‐associated virus serotype 9‐tetracystein (AAV9‐TC) labeled with a multichelator Jai Woong Seo1; Lisa Mahakian2; Elizabeth Ingham2; Spencer Tumbale3; Shahin Shams2; Eduardo Silva2; Katherine Ferrara2 1
Stanford University, USA; 2 Biomedical Engineering, UC Davis, USA;
3
Radiology, Stanford, USA
Objectives Adeno‐associated viruses (AAVs) are typically single‐ stranded deoxyribonucleic acid (ssDNA) encapsulated within 20‐nm protein capsids. AAV capsid engineering has recently resulted in tissue‐specific capsids that enhance delivery in rodents.1 The AAV biodistribution has previously been evaluated invasive methods; in vivo imaging of reporter proteins has been applied to monitor transduction over time.2 The pharmacokinetics of the viral capsid has not been yet characterized through in vivo imaging. AAV labeling with positron emitters is challenging due to two issues: 1) the injected dose in rodent studies is fairly low (typically ~1 × 1012 vector genome (Vg) which is on the order of 1.6 pmol) and 2) short half‐life positron emitters (F‐18: t1/2 = 109.7 minutes and Ga‐68: t1/2 = 67.7 minutes) with high specific activity are not
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feasible for AAV labeling due to the extended blood circulation time of some AAVs. To overcome these limits, we established a reliable AAV labeling method using a multichelator with Cu‐64 (t1/2 = 12.7 hours). Methods To evaluate the PK of AAVs by PET, the site‐specific labeling of the AAV was achieved with AAV9‐tetracystein (AAV9‐TC, known to have a brain tropism) and a maleimide‐multichelator ((NOTA)8‐PEG27‐MI, 2) as shown in Figure 1B. The multichelator (NOTA)8‐PEG27‐ NH2 (1) was synthesized on solid phase and functionalized to (NOTA)8‐PEG27‐MI (2) (Figure 1A). We evaluated 1) the incorporation efficiency of Cu(II) by titering the chelator/Cu(II) ratio and 2) the transduction efficiency of (NOTA)8‐PEG27‐MI‐conjugated AAV9‐TC in human embryonic kidney cells 293T (HEK293T) by measuring the GFP level. Cu‐64 (74 MBq, 2 mCi) were combined with (NOTA)8‐PEG27‐MI (2, 35 pmol) in an ammonium citrate buffer for 30 min. This mixture was immediately reacted with AAV9‐TC (3 × 1013 Vg, 50 pmol), which had disulfide reduced to cysteine by TCEP in PBS for 30 min. After a 1‐hour incubation, 64Cu‐AAV9‐TC was purified by a size‐ exclusion column and filtered and administered to C57BL/6 mice (n = 3) through the tail vein for PET scans at 0, 4, and 21 h and biodistribution at 21 h. Results Multichelators ((NOTA)8‐PEG27‐NH2 (1) and (NOTA)8‐ PEG27‐MI (2)) were obtained with >95% purity. The transduction efficiency assay demonstrated that the conjugation of (NOTA)8‐PEG27‐MI (2) to the AAV9‐TC does not hamper AAV9‐TC transduction. Radiolabeling of AAV9‐TC via incorporation of Cu‐64 to (NOTA)8‐ PEG27‐MI (99% on ITLC in 30 min) afforded 64Cu‐ AAV9‐TC with a 6% yield (4.88 MBq (132 μCi)). Systemic administration of 64Cu‐AAV9‐TC and PET image analysis resulted in estimates of the blood half‐life of AAV‐TC (2.4 hours, one‐phase decay) and time activity curve (Figure 1C). The biodistribution of 64Cu‐AAV‐TC (21 h) demonstrated that the brain uptake of 64Cu‐AAV9‐TC is 0.62 ± 0.027% ID/g and the highest uptake organ was liver (19.3 ± 1.05% ID/g). The multichelator approach afforded high molar activity for the radiolabeled AAV9‐ TC (~1.6 MBq/pmol Vg (44 μCi/pmol Vg)). Conclusions We successfully achieved a Cu‐64 radiolabeling of AAV9‐ TC by the multichelator‐maleimide ((NOTA)8‐PEG27‐MI, 2) approach. Here, we report an initial PET study of AAVs systemically administered through the tail vein in rodents. ACKNOWLEDGEMENTS We appreciate the assistance of Viviana Gradinaru and Tatiana Dobreva in this work and acknowledge that AAV9‐TC is from AAV9 discovered by Dr. James Wilson at University of Pennsylvania.
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RE FER EN CES 1. Mingozzi, F., & High, K. A. (2011). Therapeutic in vivo gene transfer for genetic disease using AAV: progress and challenges. Nat Rev Genet, 12(5), 341–355. 2. Xu X, Yang J, Cheng Y. (2011). Pharmacokinetic study of viral vectors for gene therapy: progress and challenges, viral gene therapy, Dr. Ke Xu (Ed.), ISBN: 978‐953‐307‐539‐6, InTech
Keynote l ecture 3 O-23 | Catalyzing the development and use of radiopharmaceuticals with total‐body PET Simon Cherry UC Davis
Catalyzing the development and use of radiopharmaceuticals with total‐body PET Simon R. Cherry Departments of Biomedical Engineering and Radiology University of California, Davis, The EXPLORER consortium recently completed construction of the world's first total‐body PET/CT scanner.1–3 The 194.8 cm axial field of view of the EXPLORER scanner is sufficient to cover the entire human body in a single acquisition and allows total‐ body pharmacokinetic studies with frame times as short as 1 second.3 Two smaller scale EXPLORER systems also have been developed for preclinical nonhuman primate imaging4 and companion animal veterinary medicine applications.5 The large increase in sensitivity arising from total‐body coverage, as well as increased solid angle for detection at any point within the body, leads to roughly a factor of 40 signal gain over conventional PET/CT and PET/MR scanners. This allows whole‐body PET studies to be acquired with unprecedented count density, improving the signal‐to‐noise ratio of the resulting images. Alternatively, the sensitivity gain can be used to acquire high‐quality PET images at radiation doses on the order of that received for a roundtrip transatlantic flight, or with very short scanning times. These capabilities could have a profound influence on how PET is used both in biomedical research and clinical practice.1,2 This new molecular imaging platform offers exciting opportunities for radiopharmaceutical science. The total‐body pharmacokinetics of novel radiotracers can be studied in the entire body simultaneously, and the high sensitivity permits imaging for an additional five half‐lives. For example, imaging of 18F labeled compounds out to 18 hours has been demonstrated, and 89 Zr‐labeled agents have been followed for a month from a single injection. This will be invaluable to study the targeting of these radiotracers, clearance and optimal
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imaging times, as well as accurate dosimetry. Furthermore, adequate imaging can be conducted extremely low activities, allowing early study of difficult to synthesize (low yield) radiotracers, as well as distribution of short‐lived radiotracers over much larger distances. This presentation will discuss the design and technical capabilities of the EXPLORER PET/CT scanner and report on the first human studies using a range of different protocols that provide initial evidence that support the capabilities of this system.3 The impact on radiopharmaceutical science provided by the ability to perform total‐body pharmacokinetic imaging will be highlighted. R EF E RE N C E S 1. Cherry SR, Badawi RD, Karp JS et al. Total‐body imaging: transforming the role of positron emission tomography. Science Translational Med 2017; 9: eaaf6169 2. Cherry SR, Jones T, Karp JS et al. Total‐body PET: maximizing sensitivity to create new opportunities for clinical research and patient care. J Nucl Med 2018; 59: 3‐12. 3. Badawi RD, Shi H et al. First human imaging studies with the EXPLORER total‐body PET scanner. J Nucl Med 2019; doi: https://doi.org/10.2967/jnumed.119.226498 (Epub ahead of print) 4. Berg E, Zhang X, Bec J et al. Development and evaluation of mini‐EXPLORER: a long axial field‐of‐view PET scanner for nonhuman primate imaging. J Nucl Med 2018; 59:993‐998. 5. Lyu Y, Lv X, Liu W et al. Mini EXPLORER II: a prototype high sensitivity PET/CT scanner for companion animal whole body and human brain scanning. Phys Med Biol 2019; doi: https:// doi.org/10.1068/1361‐6560/aafc6c (Epub ahead of print)
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W i l e y aw a r d s e s s i o n O-24 |
11
C‐Trifluoromethylation of primary aromatic amines with [11C]CuCF3 via diazonium salts generated in situ
Nicholas Young; Carlotta Taddei; Victor Pike National Institute of Mental Health, USA
Objective An ability to radiolabel the trifluoromethyl (CF3) group in diverse molecules with 18F or 11C in high molar activity has recently gained interest in positron‐emission tomography (PET) radiotracer development.1 Diazonium salts can be utilized as precursors in 11C‐trifluoromethylation reactions with [11C]CuCF3 to produce 11C‐ trifluoromethylated arenes in high yields.1 However, diazonium salts can be difficult to synthesize and isolate due to their low stability.[2] Several non‐radiochemical studies have demonstrated that diazonium salts produced in situ can be effective intermediates for the conversion of aromatic primary amino groups into other functionalities.3–5 Herein, a new method was developed to replace a primary aromatic amino group directly with a 11 C‐trifluoromethyl group via a diazonium salt generated in situ. Methods [11C]CuCF3 was prepared from [11C]fluoroform by treatment with CuBr in the presence of t‐BuOK in DMF.1 Amine, t‐butyl nitrite, and HCl solutions were prepared
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SCHEME 1
11
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C‐Trifluoromethylation of primary aromatic amines
in DMF under inert atmosphere. After cooling the aromatic amine (50 μmol) to 0°C, HCl (2.0 equiv.) was added and allowed to mix for 5 min at 0°C. Then t‐butyl nitrite (1.1 equiv.) was added and allowed to react for 15 min at 0°C, yielding the diazonium salt solution. This was then quickly transferred to the reaction vial containing [11C] CuCF3 in DMF, first kept at −42°C for 10 min and then at RT for over 10 min (Scheme 1, A). The reaction mixture was quenched with MeCN:H2O (50:50) and analyzed with radio‐HPLC. Radiochemical yields were estimated from radio‐chromatograms by peak integration of [11C] products and unreacted [11C]CuCF3. Results Initially, experiments were conducted with aniline as a substrate to determine a time‐efficient and substrate‐ versatile route. The optimized time conditions gave [11C] trifluorotoluene in up to 45 ± 6% yield. These conditions were then tested on different para‐substituted aromatic primary amines and successfully produced the 11C‐ trifluoromethylated products in moderate to high yields (Scheme 1, B). Aniline with bromine or chlorine in para position gave the corresponding 11C‐trifluoromethylated products in 35% and 23% yields, respectively, whereas ortho‐substituted bromoaniline gave no yield. Moderate yields of 22%, 11% and 18% were obtained with para‐ substituted thiomethyl, trifluoromethyl and nitro substituents, respectively. In contrast, only 7% yield was obtained with a meta‐nitro substituent. Conclusions 11 C‐Trifluoromethylation of various aromatic primary amines with [11C]CuCF3 was achieved in moderate to high yields. Further investigations need to be performed to optimize the reaction conditions and confirm the reproducibility of results. In addition, a wider range of substrates bearing electron‐withdrawing or electron‐
donating groups will be explored to test the overall scope of the presented methodology. ACKNOWLEDGEMENTS This work was supported by the Intramural Research Program of the National Institutes of Health (NIMH; ZIA MH002793). The authors would like to acknowledge Dr. Sanjay Telu and Dr. Bo Yeun Yang for their advice and help during this work. RE FER EN CES 1. Haskali M. B., Pike, V. W., Chem. Eur. J. 2017, 23, 8156. 2. Zollinger, H., Acc. Chem. Res. 1973, 6, 335. 3. Wang X., et al., J. Am. Chem. Soc. 2013, 13, 10330. 4. Zhao, C., et al., J. Syn. Lett. 2014, 25, 1577. 5. Yang, H., et al., J. Am. Chem. Soc. 2015, 137, 1362.
Wil e y Aw a r d S e ss i on O-25 | A long‐acting radiolabeled RGD analogue 177Lu‐AB‐3PRGD2 for targeted radiotherapy of tumor Hannan Gao1; Guangjie Yang1; Chuangwei Luo1; Bing Jia1; Jiyun Shi2; Fan Wang1 1
Peking University, China; 2 Institute of Biophysics, CAS, China
Objectives Targeted radiotherapy (TRT) is an emerging approach for tumor treatment. Previously, 177Lu‐labeled 3PRGD2 (3 PEG4 linkers modified RGD dimmer peptide) has demonstrated great potential for integrin αvβ3‐targeted radiotherapy with two‐dose (111 MBq × 2) regimen.
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The structural strategy of 177Lu‐AB‐3PRGD2 (A), representative nanoScan SPECT/CT images of 177Lu‐3PRGD2, and 177Lu‐AB‐ 3PRGD2 in U87MG tumor model at different time points (B), and TRT of 177Lu‐AB‐3PRGD2 (18 MBq), 177Lu‐3PRGD2 (18 MBq), 177Lu‐AB (18 MBq), and control group in U87MG tumor model (C). White dotted circle indicates the U87MG tumor
FIGURE 1
However, due to its fast blood clearance, high‐dose or multiple drug delivery was indispensable while using 177 Lu‐3PRGD2. Here, we introduced an albumin binding motif D‐lys‐4‐(p‐iodophenyl) butyric acid (termed: AB) into the TRT tracer structure, aimed to enhance the tumor uptake and prolong the tumor retention time of radiotracer, hence potentially improve the therapeutic efficacy at a relatively low dose. Methods The nanoScan SPECT/CT imaging, biodistribution, blood clearance, and TRT of 177Lu‐AB‐3PRGD2was carried out in U87MG tumor model with 177Lu‐3PRGD2, 177Lu‐AB as controls. For imaging, the mice were injected with 18.0 MBq dose via tail vein and imaged at 1, 4, 12, 24, 48, and 72 h p.i. For biodistribution, the mice were injected with 0.74 MBq dose via tail vein and sacrificed for organs harvesting and gamma‐counting at 1, 4, 24, and 72 h p.i. For TRT experiment, the mice were injected with 18.0 MBq dose for each group via tail vein, tumor volume and body weight were monitored every other day. Results The radiotracers were determined at >95% RCP by radio‐ HPLC before in vivo applications. As showed in Figure 1B, 177Lu‐AB‐3PRGD2 showed remarkly higher tumor uptake (imaging quantified tumor ROI (region of interest): 14.48 ± 3.41, 21.55 ± 2.18, 17.12 ± 1.27, 10.49 ± 0.91, 5.52 ± 0.83 and 2.50 ± 0.42 %ID/mL at 1, 4, 12, 24, 48, and 72 h p.i., respectively) and longer tumor retention time than that of 177Lu‐3PRGD2 (imaging quantified tumor ROI: 3.43 ± 0.64, 3.62 ± 0.84, 2.82 ± 0.22, 2.66 ± 0.21, 1.89 ± 0.18, and 1.01 ± 0.40 %ID/mL at 1, 4, 12, 24, 48, and 72 h p.i., respectively), which resulted in 4.2 times increased tumor AUC (area under curve) during 72 h p.i. Biodistribution results were consistent with imaging results. The TRT results showed that the tumor volume doubling time was delayed from 3 days p.i. (control group)
to 4 days p.i. for 177Lu‐AB (18 MBq), 5 days p.i. for 177Lu‐ 3PRGD2 (18 MBq), respectively, and further delayed to 11 days p.i. for 177Lu‐AB‐3PRGD2 (18 MBq). The U87MG tumor growth was remarkably inhibited with 177Lu‐AB‐ 3PRGD2 at a low dose as 18 MBq, which is comparable to the therapeutic efficacy of 177Lu‐3PRGD2 at a high dosage of 111 MBq, according to our previous study data. Conclusions The 177Lu‐AB‐3PRGD2 is a promising TRT agent for integrin αvβ3 overexpressed tumors with much lower dose than previous TRT tracer 177Lu‐3PRGD2. By introducing an albumin binding moiety, 177Lu‐AB‐3PRGD2 showed remarkably enhanced accumulation and prolonged retention in U87MG tumors, achieved about 4.2 times increased tumor AUC than 177Lu‐3PRGD2 during 72 h p.i., which guaranteed the same outcome with much lower dose and less frequency of administration. Since the single dose TRT at 18 MBq showed notable tumor regression until day 10, a repeated dose regimen might be scheduled with 10‐day interval to get prolonged therapy efficacy.
W i l e y aw a r d s e s s i o n O-26 | Development of a radiation detector for miniaturized analysis of radiopharmaceutical samples via microchip electrophoresis Jason Jones1; Noel Ha2; R. Michael van Dam3 1
UCLA, USA; 2 Lawrence Berkeley National Laboratory, USA; 3 Crump
Institute for Molecular Imaging, UCLA, USA
Background Capillary electrophoresis (CE) is a rapid, high‐resolution analytical separation technique that has the benefit,
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compared to high‐performance liquid chromatography (HPLC), of being easily miniaturized, i.e., microchip electrophoresis (MCE). CE has been used previously in the analysis of PET[1] and SPECT[2] radiopharmaceuticals; however, use of MCE for this purpose has not been reported. In fact, there is no report of a radiation detector integrated into an MCE system[3]. We propose that radio‐MCE would be an attractive method for analysis of PET radiopharmaceuticals, and here, we integrate a radiation detector into a previously developed hybrid MCE chip capable of UV detection with high‐sensitivity and high‐ resolution separation, including the separation of fluoro‐ 3′‐deoxythymidine (FLT) from its known impurities[4]. To achieve the highest sensitivity without compromising spatial resolution for radiation detection in this modality, we focus on positron detection; gamma detection is low sensitivity and reduces spatial resolution and therefore sample separation. Therefore, a solid‐state positron‐ detector was chosen for this work. Methods MCE was performed in a “hybrid” device comprising a PDMS microfluidic sample injection chip (with 4 nL injection volume) and a PDMS detection chip connected by a 20‐cm‐long fused‐silica capillary[5] (Figure 1A). The detection chip contains a Z‐shaped flow cell for UV absorbance detection and was modified in this work to also include a radiation detector. A 2 mm × 2 mm avalanche photodiode (APD) solid‐state detector was used. This type of detector is highly sensitive to short‐range positrons if positioned close to the source and are relatively insensitive to longer‐range annihilation gamma rays, limiting the sensitive detection region to the positron range (i.e., a few mm). The APD is positioned 100 μm below the sample channel, separated by a PDMS membrane (Figure 1B). MCE separations were performed at a field strength of 200 V/cm using 30 mM phosphate buffer with 100 mM sodium dodecyl sulfate. We used [18F]3′‐fluoro‐3′‐deoxythymidine ([18F]FLT) as a model compound for preliminary studies. We injected
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and analyzed several samples as a preliminary demonstration of this device: purified [18F]FLT with and without coinjection with reference standard, as well as crude [18F] FLT, and purified [18F]FLT spiked with known amounts of impurities (thymidine, stauvidine, chlorothymidine, and nosyl acid). Electropherogram peaks were fit to Gaussian curves to analyze migration time, peak area, and peak width. Samples were also injected into analytical HPLC (mobile phase EtOH:H2O 1:9 (v/v) with 20 mM phosphate monobasic; C18 Luna column 4 mm × 250 mm; 1.5 mL/ min) for comparison. Results UV migration time of [18F]FLT was found to be 205 ± 5 s, with consistent symmetric peak shape across all injections (Figure 1D). Implementation of the APD did not compromise the separation efficiency of our MCE device; [18F]FLT was successfully separated from all impurities with baseline resolution (Figure 1C). In the crude sample of [18F]FLT, we observed a single 20‐ s‐wide radiation peak corresponding to [18F]FLT peak as well as UV peaks corresponding to thymidine, stavudine, CLT, and nosyl acid (Figure 1E). Compared to radio‐HPLC (Figure 1F), the migration time was faster (200 s vs 7.5 m), and the FWHM of the radiation peak in MCE was narrower than in HPLC (14 s vs 25 s FWHM.) Experiments to measure limits of detection for this device are currently in progress. Conclusions We have successfully demonstrated the integration of a radiation detector into an MCE device, and successfully detect a narrow radiation peak from the 4 nL sample having concentration of a typical formulated PET tracer. This device can generate electropherograms from both the UV absorbance and radiation detectors. This information can be combined to provide information about chemical and radiochemical purity of radiopharmaceutical samples, with migration time and/or coinjection used to confirm radiochemical identity. Future work will focus on
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modifications to reliably detect [18F]fluoride in samples as well as detailed characterization of radiation detector sensitivity. ACKNOWLEDGEMENTS We gratefully acknowledge support from the NIA, NCI, and NIBIB. R EF E RE N C E S 1. Pentoney et al., Anal. Chem. 61: 1642–1647, 1989. 2. Jankowsky et al., J ChromB 724: 365–371, 1999. 3. Ha et al., Micromachines 8: 337, 2017. 4. Ly et al., Anal Bioanal Chem 410: 2423–2436, 2018. 5. Ha et al., Analytica Chimica Acta 985: 129–140, 2017.
Wiley a ward session O-27 | Develop a peptide‐based PET radiotracer for imaging PD‐L1 expression in cancer Kuan Hu1; Ming‐Rong Zhang2; Masayuki Hanyu3; Lin Xie3; Yiding Zhang4 1
National Institute of Radiological Sciences, Japan; 2 Department of
Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3 National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology
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(QST), Japan; 4 Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
Objectives Immune checkpoint blockade has emerged as a promising cancer treatment paradigm. Unfortunately, there are still a large number of patients and malignancies that do not respond to this therapy. A major barrier to validating biomarkers for the prediction and monitoring of responders to clinical checkpoint blockade has been the lack of imaging tools to accurately assess dynamic immune checkpoint expression. The programmed cell death ligand 1 (PD‐L1) is expressed in many cancers and is an important contributor to the maintenance of immunosuppressive tumor microenvironment. PD‐L1 is a prominent target for cancer immunotherapy.1,2 An octapeptide (PWZ‐1), was recently screened with high binding affinity for PD‐L1 (KD ≈ 10 nM). Here, we examine the feasibility of developing the octapeptide as a radiotracer for noninvasive detection of PD‐ L1 expression in tumors by PET. Methods PWZ‐1 peptide was conjugated with DOTA as a chelator for radioisotope labelling. The binding affinity of PWZ‐1‐ NOTA was evaluated by surface plasmon resonance. PWZ‐1 was subjected to radiolabeling with copper‐64 and the radiolabeling conditions were optimized. The resulting [64Cu]PWZ‐1 was assessed for stability in saline and in mouse serum. The in vitro specificity of the radiolabeled peptides for two PD‐L1(+) cell lines MDA‐
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MB‐231 and B16F10 was tested. Next, we performed small animal PET imaging in tumor‐bearing mice with the radiolabeled peptide which was injected via tail vein. The ex vivo biodistribution of [64Cu]PWZ‐1 in mice was also conducted. Results Surface plasmon resonance showed the DOTA‐conjugated PWZ‐1 with a similar binding affinity with PWZ‐1. Synthesis of [64Cu]PWZ‐1 provided radiochemical purity >99% after purification and formulation. Biodistribution in mice demonstrated 5‐10 percentage of injected dose per gram (%ID/g) in MDAMB231and B16F10 tumors, respectively, at 1 h postinjection, with high binding specificity noted with coinjection of excess unlabelled PWZ‐1. PET imaging showed high uptake contrast in all tumor models tested. Conclusion We demonstrated the specificity of [64Cu]PWZ‐1 to detect PD‐L1 expression in multiple xenograft models with variable PD‐L1 expressions and described its biodistribution and pharmacokinetics. In addition, the radiolabeling and purification conditions tested for preparation of [64Cu]PWZ‐1 could be easily modified to facilitate a kit preparation of the radiotracer for PD‐L1 imaging. Such 64 Cu‐labeled PD‐L1 imaging agents with short biological half‐life and fit within the routine clinical work flow enables therapy monitoring and stratification of patients in the field of immuno‐oncology. R EF E RE N C E S 1. Roy LM, et al. Proc. Natl. Sci. USA. 2015, 112, E6506‐14. 2. Truillet C, et al. Bioconjugate. Chem. 2018, 29, 96‐103.
R a d i o c h e m i s t r y ‐ 1 1 C a nd ot he r p os i t r on e m i t t e r s O-28 | In‐loop carbonylation‐a novel and simplified method for carbon‐11 labeling of drugs and radioligands Melodie Ferrat2; Youssef El Khoury2; Kenneth Dahl1; Christer Halldin2; Magnus Schou3 1
CAMH and University of Toronto, Canada; 2 Karolinska Institutet,
Sweden; 3 AstraZeneca PET Centre at Karolinska Institutet, Sweden
Objectives Transition metal–mediated carbonylation is a versatile method for introducing carbon‐11 (11C) into drug‐like molecules and radioligands. The synthesis is usually performed by automated system at high pressure and temperature and extended reaction times. However,
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radiochemistry using [11C]CO is challenging due to its poor solubility in organic solvents, its high dilution in inert gas, and also difficult to handle for being a radioactive gas. The main objective of this project was to develop a novel and simplified method for 11C‐carbonylation, in which the radiolabeling reaction takes place on the interior surface of an ordinary stainless‐steel loop commonly used for high‐performance liquid chromatography (HPLC). Methods 11 C was produced by a GEMS PET trace cyclotron, using 14 N(p,α) 11C nuclear reaction performed by proton bombardment of a pressurized gas target containing nitrogen (99.9%) and oxygen (0.5%) to produce [11C]CO2. The produced [11C]CO2 was transferred into a [11C]CO‐synthesizer prototype in a shielded hot‐cell, located at the adjacent PET radiochemistry laboratory. [11C]CO2 was reduced to [11C]CO by the use of a pre‐heated column (850°C) filled with molybdenum powder. The [11C]CO was transferred at room temperature (r.t), into a stainless‐steel loop (2 mL) used for high‐performance liquid chromatography (HPLC), pre‐loaded with the reaction mixture (aryl halide, palladium‐source, supporting ligand, and nucleophile in anhydrous solvent). The loop was kept for 5 min at the desired temperature (r.t. to 110°C). Reaction mixtures were analyzed using HPLC with ultraviolet (UV) and radiation detection. The radiochemical yield (RCY) was assessed by radio‐HPLC and the trapping efficiency (TE) was calculated by dividing the radioactivity delivered to the product vial with the total radioactivity (taking untrapped radioactivity during trapping into the loop as well as volatile radioactive products in the product vial into account). Results This new in‐loop method was optimized on a model substance called N‐benzyl benzamide, which was obtained in quantitative radiochemical yield (RCY = 99 ± 0.5%) and trapping efficiency (TE = 99 ± 0.5%). In‐loop method was next applied for [11C]benzoic acid (RCY > 99%, TE > 91%), a series of 11C‐labeled esters, namely, [11C]methyl benzoate (RCY > 99%,TE > 93%), [11C]ethyl benzoate (RCY > 99%, TE > 96%), and [11C]phtalide (RCY > 99%, TE > 88% ). A set of pharmaceuticals was radiolabelled using un‐optimized conditions. Excellent yields were obtained for H3 receptor radioligand [11C]AZ13198083 (RCY = 93%,TE = 98%), the PARP inhibitor [11C]olaparib (RCY > 99%,TE = 97%), and the dopamine D2 receptor antagonist [11C]raclopride (RCY = 89%,TE = 88%). Modest yield was obtained for [11C]FLB457 (RCY = 79%,TE = 54%) (Figure 1a). The method proved to be useful to provide 11C‐ labeled amide, esters, and carboxylic acids (Figure 1b). Imaging demonstrated that the majority of the radioactivity was trapped in the first quarter (~0.5 mL) of the stainless steel tubing.
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Conclusion A new versatile in‐loop radiochemical method has been described and applied to the labeling of 11C‐amides, 11C‐ esters, a 11C‐labeled lactone, and a 11C‐labeled carboxylic acid in moderate to excellent radiochemical yields (Figure 1b). The method is operationally simple, remarkably efficient for most substrates, and is well suited for automation. The greatest advantage is that transfer losses between the reactor and the preparative HPLC system are minimized. This methodology has the potential to be widely implemented in the development of new tracer molecules for PET imaging.
R EF E RE N C E S 1. Dahl K, Schou M, Amini N, Halldin C. Eur.J.Org.Che. 2013, 1228‐1231 2. Långström B, Itsenko O, Rahman O. J Label Compd Radiopharm, 2007, 50, 794‐810 3. Wilson AA, Garcia A, Jin L, Houle S. Nucl Med Bio. 2000, 27, 529‐53 4. Dahl K, Schou M, Ulin J, Sjöberg C‐O, Farde L, Halldin C. RSC Adv., 2015, 5, 88886‐88889 5. Chow SY, Stevens MY, Akerbladh L, Bergman S, Odell LR. Chem.Eur.J. 2016, 22, 9155‐9161
ACKNOWLEDGEMENTS • This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska‐Curie grant agreement no. 675071. • The authors would like to thank members of PET group at Karolinska Institutet.
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DISCLOSURES • MS is an employee and shareholder at AstraZeneca. The other co‐authors declare no conflicts of interest.
Radiochemistry ‐ emitters
11
C and other positron
O-29 | Palladium/copper‐mediated rapid 11C‐ cyanation of (hetero)arylstannanes Zhouen Zhang; Takashi Niwa; Yasuyoshi Watanabe; Takamitsu Hosoya RIKEN Center for Biosystems Dynamics Research, Japan
Objectives Recently, we developed a palladium(II)‐mediated rapid 11 C‐cyanation of (hetero)arylborons with [11C]NH4CN/ NH3 that enabled efficient preparation of 11C‐ cyanoarene‐containing PET tracers.1 To further expand the scope of synthesizable [cyano‐11C]heteroaromatic nitriles, we have established an alternative method using ready available (hetero)arylstannanes as precursors (Figure 1). Methods [11C]NH4CN was generated by passing the gas mixture of [11C]CH4 and NH3 over an oven containing a platinum wire catalyst at 990°C. The obtained gaseous mixture containing [11C]NH4CN and NH3 was trapped in a reaction mixture containing a Pd(II) complex, CuCl and (hetero) arylstannanes, followed by heating at 110°C for 5 min.
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The radiochemical yield (RCY) of [cyano‐11C](hetero)aromatic nitriles from [11C]NH4CN was determined by radio‐HPLC analysis of the reaction mixture. Results We found that the combined use of palladium(II) and copper complexes was crucial for obtaining the desired [cyano‐11C](hetero)aromatic nitriles in high RCYs, indicating a synergistic effect of these two complexes for this transformation (Figure 1). This 11C‐cyanation showed excellent compatibility to various heteroaromatic structures. By using this method, [cyano‐11C]topiroxostat was successfully synthesized, which could be a potential PET tracer for xanthine oxidase imaging study. We have also demonstrated the utility of this rapid 11C‐cyanation for synthesizing 11C‐labeled heteroaromatic rings. For example, the rapid 11C‐cyanation of 2‐(tributylstannyl) pyrimidine (1) afforded [cyano‐11C]2‐cyanopyrimidine (2), which was further transformed into [11C]2‐(1H‐ tetrazol‐5‐yl)pyrimidine (3) and [11C]6‐(pyrimidin‐2‐yl)‐ 1,3,5‐triazine‐2,4‐diamine (4) in a one‐pot manner (Figure 2). Conclusions We have achieved an efficient 11C‐cyanation of (hetero) arylstannanes with [11C]NH4CN by combined use of palladium and copper complexes, which allowed for the synthesis of a broad range of [cyano‐11C](hetero)aromatic nitriles and their derivatives in high RCYs. This 11C‐ cyanation method would greatly contribute to the synthesis of 11C‐labeled PET tracers. ACKNOWLEDGEMENTS This work was supported by JSPS KAKENHI 16K08339, J‐AMED under grant numbers JP18am0101098, the Pioneering Project “Chemical Probe” from RIKEN, and JSPS A3 Foresight Program.
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RE FER EN CES 1. Zhang Z, Niwa T, Watababe Y, Hosoya T. J. Label. Compd. Radiopharm. 2017, 60, S48. 2. Zhang Z, Niwa T, Watababe Y, Hosoya T. Org. Biomol. Chem. 2018, 16, 7711
Radiochemistry ‐ emitters
11
C and other positron
O-30 | Rapid, one‐pot radiosynthesis of [carbonyl‐11C]formamides from primary amines and [11C]CO2 Federico Luzi; Salvatore Bongarzone; Antony Gee King's College London, UK
Objectives Formamides are common motifs of biologically‐active compounds (e.g., formoterol, octotiamine, and fursaltiamine)1 and are frequently employed as intermediates to yield benzimidazoles.2 A rapid, simple, and reliable route to [carbonyl‐11C]formamides would enable access to this important class of compounds as in vivo PET imaging agents. The methods currently available for 11C‐ formylation proceed via the initial production of more reactive synthons, such as [11C]formaldehyde or [11C]formates.2–5 However, these methods require harsh reaction conditions,3,4 long processing times, and the time‐ consuming production of labelled secondary precursors as starting materials (e.g., [11C]CH3I or [11C]CH3OH).3,5 To our knowledge, no method has yet been developed that directly utilises cyclotron‐produced [11C]CO2 for 11C‐ formylation reactions. Here, we report the rapid, one‐pot
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Figure 1. Reaction scheme for the
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11
C‐formylation of amines.
11
C‐formylation of amines via the reduction of [11C]isocyanate intermediates formed directly from cyclotron‐ produced [11C]CO2. Methods The method exploits a simple one‐valve, one‐vial synthesis set‐up. Cyclotron‐produced [11C]CO2 was bubbled directly from the target into a solution of BEMP (2‐tert‐butylimino‐ 2‐diethylamino‐1,3‐dimethylperhydro‐1,3,2‐diazaphosphorine) and benzylamine (time taken: ca. 2 min from EOB = “end of delivery” (EOD)).6 POCl3 was subsequently added and allowed to react for 2 minutes at low temperature (0°C) to produce the corresponding [11C]isocyanate.6 The [11C]isocyanate was subsequently reduced using an excess of sodium borohydride as reducing agent for 15 min at room temperature, yielding the [carbonyl‐11C] formamide derivative. Results Greater than 90% of the activity delivered from the target was trapped in the vial. The formation of the crude [11C] isocyanate was achieved in >80% radiochemical yield (RCY, based on HPLC analysis of the crude product). Reduction with an excess of sodium borohydride produced the corresponding [carbonyl‐11C]formamide derivative in moderate yields (RCY = 37.7% based on HPLC analysis of the crude product) in less than 23 minutes from end of bombardment (EOB) to end of synthesis (EOS). Conclusions This proof‐of‐concept study demonstrates the feasibility of 11C‐formylation of amines using the primary [11C] CO2 synthon. The method proceeds via the formation of a [11C]isocyanate derivative, which is achieved in high yields, and subsequently reduced to the respective [carbonyl‐11C]formamide. Total processing time was 99% (n = 5). After distillation, [11C]formic acid was reacted with benzylamine (458 μmol) resulting in the formation of N‐[11C]benzylformamide in 90 ± 6% (n = 2) radiochemical yield based on HPLC analysis. A lower amount of benzylamine (137 μmol) was used as well, but resulted in a lower and more variable yield: 37 ± 30%. After HPLC purification, N‐[11C]benzylformamide was obtained in a radiochemical yield of 9 ± 1% (calculated from [11C] CO2) with a radiochemical purity of 67 ± 2% (before 37 ± 30%). The total synthesis time was less than 25 min from end of beam. Results with other carbon‐11 labeled formamides are depicted in scheme 1,
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all in a radiochemical purity comparable to N‐[11C] benzylformamide. Discussion We investigated the influence of the concentration of the reducing agent (LiEt3BH) and found that between 0.2 M and 0.4 M was optimal for quantitative reduction of [11C] CO2 to [11C]formic acid. Lower concentrations resulted in partly unreacted [11C]CO2 and higher concentration in over‐reduction to [11C]methanol. The reaction of [11C] formic acid with benzylamine led to a high radiochemical yield (determined by HPLC) up to 90 ± 6% by using the coupling agent BOP with a base, while a maximum yield of 13% was observed without using BOP. Furthermore, we investigated the influence of the benzylamine amount and observed that 45.8 μmol provided no conversion while 137 to 458 μmol provided, respectively, 37 ± 30% and 90 ± 6% of N‐[11C]benzylformamide. The optimized method was applied to other amine precursors and showed that primary, secondary, tertiary, and aromatic [11C]formamide formation is possible. Conclusions A fast and easy method for the synthesis of radiolabelled N‐[11C]benzylformamide has been developed. This method was applied in the synthesis of a small series of radiolabelled formamides by using different amine precursors. Further optimization, including determination of the molar activity, is ongoing as well as application of these new carbon‐11 labeled building blocks in the synthesis of novel PET tracers. ACKNOWLEDGEMENTS The project is financially supported by The Netherlands Organization of Scientific Research (NWO).
RE FER EN CES 1. Chen B‐C, et al., Tetrahedron Lett., 2000, 41, 5453 2. (a) Roeda D, Dollé F, Crouzel C. J. Labelled Cpd. Radiopharm., 2001, 44, S126; (b) Van der Mey M, et al. Bioorg. Med. Chem., 2006, 14, 4526–4534
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Radiochemistry ‐ emitters
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11
C and other positron
O-33 | Rapid and efficient BEMP‐mediated synthesis of 11C‐labelled benzimidazolones using [11C]carbon dioxide Kaisa Horkka1; Kenneth Dahl2; Christer Halldin1; Magnus Schou3 1
Karolinska Institutet, Sweden; 2 CAMH and University of Toronto,
Canada; 3 AstraZeneca PET Centre, Karolinska Institutet, Sweden
Objectives Benzimidazolones are common structural motifs in drug‐ like molecules and radioligands. An example of a benzimidazolone PET tracer is (S)‐[11C]CGP12177, a radioligand for beta‐adrenoceptors in the human myocardium and airways.[1, 2] The current project aimed to develop a novel method for radiolabelling benzimidazolone motifs starting from cyclotron‐produced [11C] carbon dioxide ([11C]CO2) and thereby precluding the use of 11C‐labelled phosgene for this purpose. Methods No‐carrier‐added [11C]CO2 was produced using an on‐site PETtrace cyclotron (GEMS, Uppsala, Sweden). The produced [11C]CO2 was further concentrated and introduced in a stream of helium into a reaction vessel pre‐charged with the appropriate o‐phenylenediamine and BEMP in acetonitrile. After 2 minutes, a solution of DBAD and tributylphosphine in acetonitrile were added. The reaction was quenched after 4 minutes, and the radiochemical yield (RCY) was determined by radio‐HPLC. The trapping efficiency (TE) was calculated by dividing the radioactivity remaining in the reaction mixture after the quench with that delivered to the vial. RCYs and TEs are presented as an average of two experiments, unless otherwise stated.
Results The formation of the unsubstituted [11C]benzimidazolone was selected as model reaction, a compound that was obtained in a near quantitative RCY (99 ± 0.5%, n = 3) and TE (98 ± 0.5%, n = 3) at optimized conditions. With these reaction conditions in hand, a series (n = 6) of substituted [11C]benzimidazolones were obtained in excellent RCYs (83‐99%) and TEs (91‐97%). Electron‐ donating and withdrawing groups were well tolerated, as well as N‐monoalkyl substituents. In addition to benzimidazolones, other heterocycles were also accessible using this novel strategy, as exemplified by the synthesis of [11C]benzoxazolone (RCY = 83%, TE = 70%, n = 3) and [11C]benzothiazolone (RCY = 95% and TE = 97%, n = 3). To evaluate the utility of the methodology for the labelling of drug‐like and PET tracer molecules, it was applied to the radiosynthesis of (S)‐[11C]CGP12177. 11 C‐labelling and subsequent deprotection of the O‐ silylated precursor afforded the isolated radiotracer in an 8% RCY and molar activity of 14 GBq/μmol. Conclusions The herein reported method for the preparation of [11C] benzimidazolones is an important addition to the thin library of available methods for 11C‐labelling. This novel [11C]CO2 fixation method is simple and efficient and allows for a reliable production of 11C‐carbonylated radiotracers for PET imaging. ACKNOWLEDGMENTS This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska‐Curie grant agreement no. 675071. RE FER EN CES 1. Ueki J, Rhodes CG, Hughes JM, De Silva R, Lefroy DC, Ind PW, Qing F, Brady F, Luthra SK, Steel CJ, et al. J. Appl. Physiol. 1993, 75, 559‐565.
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2. Boullais C, Crouzel C, Syrota A. J. Labelled Compd. Radiopharm. 1986, 23, 565‐567.
Radiolabeled compounds ‐ other medical disciplines and radiopharmacology and cardiology O-34 | [11C]Metoclopramide as a PET tracer to visualize ABCB1 induction at the mouse blood‐brain‐barrier Severin Mairinger1; Viktoria Zoufal2; Thomas Wanek3; Mirjam Brackhan4; Johann Stanek2; Thomas Filip2; Michael Sauberer2; Nicolas Tournier5; Jens Pahnke4; Oliver Langer2 1
Preclinical Molecular Imaging, AIT Austrian Institute of Technology
GmbH, Austria; 2 AIT Austrian Institute of Technology GmbH, Austria; 3
Health and Environment Department, Biomedical Systems, Austrian
Institute of Technology (AIT), Austria; 4 Department of Neuro‐/Pathology, University of Oslo (UiO) and Oslo University Hospital (OUS), Norway; 5
CEA, France
Introduction There is evidence that clearance of beta‐amyloid from brain into blood is mediated by P‐glycoprotein (ABCB1) at the blood‐brain barrier (BBB). Pharmacological induction of ABCB1 is a currently investigated approach for the treatment of Alzheimer's disease. For the development of ABCB1‐inducing therapeutics, the availability of a PET tracer to measure ABCB1 function at the BBB would be very helpful. Currently, available avid ABCB1 substrates for PET (e.g., (R)‐[11C]verapamil and [11C]N‐desmethyl‐ loperamide) are not suitable to measure ABCB1 induction at the BBB due to their very low brain uptake and presence of brain‐penetrant radiolabeled metabolites. We evaluated the ability of the recently introduced weak ABCB1 substrate [11C]metoclopramide ([11C]MCP) [1] to measure ABCB1 induction at the mouse BBB. Methods [11C]MCP was synthesized in a Tracerlab FX C Pro synthesis module by O‐methylation of O‐desmethyl‐ metoclopramide with [11C]methyl triflate [1]. Groups of female C57BL/6J mice aged approximately 170 days (n = 4‐6 per group) underwent a baseline [11C]MCP PET scan followed by treatment with two different validated ABCB1 induction protocols (PCN: 25 mg/kg i.p. over 7 days or rifampicin: 10 mg/kg i.p. over 5 days) or vehicle solution (safflower oil) and a second [11C]MCP PET scan at the end of treatment. At the end of each PET scan, a small blood sample was collected from each animal and counted for radioactivity in a gamma counter. In separate
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groups of animals, radiolabelled metabolites of [11C]MCP were analysed by radio‐TLC at 15 min after injection (n = 2‐5 per group). As an outcome parameter of ABCB1 function, the elimination slope for radioactivity washout from the brain was determined from the log‐transformed brain time‐activity curves (kE,brain, h−1) [1]. All values are reported as mean ± SD. Results [11C]MCP was synthesized in a decay‐corrected radiochemical yield of 8.1 ± 1.6% (n = 15, based on [11C]methane) in a total synthesis time of 31 min with a radiochemical purity >99% and a molar activity at end of synthesis of 96.5 ± 45.3 GBq/μmol. To the radiotracer solution carrier was added (2 mg/kg) to reduce peripheral metabolism of [11C]MCP [1]. KE,brain was not significantly different between baseline, rifampicin‐ and vehicle‐ treated groups (0.687 ± 0.056 vs. 0.701 ± 0.075 and 0.775 ± 0.071 h−1, p < 0.05). Significantly higher kE,brain was observed in the PCN‐treated group (0.883 ± 0.195 h −1 , p < 0.001, 1‐way ANOVA with Tukey's test) compared to the baseline group. No significant differences between the four groups were observed in blood radioactivity concentrations measured at the end of the PET scan. In plasma and brain, the percentage of unchanged [11C] MCP at 15 min after injection was comparable for all groups (plasma: 33.9 ± 6.2%, brain: 90.9 ± 2.8%). Conclusion We established the synthesis of [11C]MCP and evaluated two validated ABCB1 induction protocols. [11C]MCP was found to lack brain‐penetrant radiolabelled metabolites. Treatment with PCN significantly enhanced washout of radioactivity from the brain, which indicated that [11C]MCP is a suitable PET tracer to measure ABCB1 induction at the BBB. RE FER EN CES 1. Pottier G, et al. J Nucl Med 2016;57:309‐314.
Radiolabeled compounds ‐ other medical disciplines and radiopharmacology and cardiology O-35 | A novel high‐throughput cassette microdosing approach to screen PET imaging agents Mingyue Sun1; Hao Xiao2; Haiyan Hong1; Aili Zhang3; Yan Zhang1; Yajing Liu2; Lin Zhu4; Hank Kung5; Jinping Qiao1 1
College of Chemistry, Beijing Normal University, China; 2 Beijing Institute
of Brain Disorders, Capital Medical University, China; 3 Collage of
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Chemistry, Beijing Normal University, China; 4 Beijing Normal University, China; 5 University of Pennsylvania, USA
Objectives Positron emission tomography (PET) is a very sensitive molecular imaging technique.1 However, the utility of this method is limited by the availability of suitable radiopharmaceuticals to probe specific targets and biology‐related disease processes. Methods to screen candidate compounds prior to radiolabeling would speed up the discovery of novel radiopharmaceuticals. Besides its high sensitivity, LC‐MS/MS provides the possibility to analyze multiple compounds simultaneously, which makes it possible to enhance the throughput of PET imaging agent screening.2 The purpose of this study is to develop a new approach using LC‐MS/MS to enhance the throughput in screening radiopharmaceutical biodistribution in the rat brain using iv injection of cassettes of “cold” candidate compounds. Methods The analytes were divided into three groups: cassette a‐c (combination of three compounds shown in the Figure 1A). We have selected three different groups of compounds targeting serotonin transporters (SERT) and vesicular monoamine transporters 2 (VMAT2) in the brain: a. serotonin transporter – group one SERT ligands (FPBM, FPBM2, and P16‐134); group two SERT ligands (P17‐021, P16‐132, and P17‐020) and group three VMAT2 ligands (AV‐133, P16‐098, and DTBZ). The rats were also divided into three groups (n = 5) by average weight: (1) the rats of group 1 were given cassette a intravenously by tail vein, then were given cassette b 30 minutes later
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and cassette c after 58 minutes; (2) the rats of group 1 were given cassette b intravenously by tail vein, then were given cassette c 30 minutes later and cassette a after 58 minutes; (3) the rats of group 1 were given cassette c intravenously by tail vein, then were given cassette a 30 minutes later and cassette b after 58 minutes. The rats were sacrificed at 60 min post‐administration. Different brain regions such as hypothalamus (HT), striatum (ST), hippocampus (HP), cortex (CX), cerebellum (CB), and remainder of the brain (RE) were isolated and were weighed immediately after dissection. Sample preparation: 4 times volumes of 1 ng/mL IS acetonitrile solution were added to the weighed harvested brain region to precipitate protein, the mixture was homogenized, vortex‐mixed, and centrifuged. The supernatants were evaporated to dryness under a stream of nitrogen, and the residue was reconstituted in acetonitrile for analysis. Results The concentrations of analytes in rat brains were calculated as percentage injected dose per gram tissue weight (%ID/gtissue). The regional distribution of FPBM and its derivative in the rat brain was found to be HT > RE > ST = CX > HP > CB. They exhibited high uptake in the brain regions expressing SERT and low uptakes in the brain regions not expressing SERT. The regional distribution of AV‐133, DTBZ, and P16‐098 in rat brain was ST > HT > HP = RE > CX > CB. VMAT2 ligands showed higher uptake in target tissue than with other brain substructures, and the pattern was in accordance with the known distribution of VMAT2. The biodistribution data of FPBM, FPBM2, AV‐133, and P16‐134
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obtained by the method matched very well with the values obtained by the standard radioactivity measurements (shown in the Figure 1B). Conclusions A novel cassette microdosing with LC–MS/MS method was used for testing the feasibility of screening PET imaging agents. The advantage of this method is that it is relatively simple and has a reasonably high throughput for testing target‐binding PET radiopharmaceuticals without the use of radioactive agents. ACKNOWLEDGMENTS This work was financially supported in part by the National Key Research and Development Program of China (2016YFC1306300) and the Beijing Natural Science Foundation (7171002).
R EF E RE N C E S 1. Lin Z, Karl P, Hank F. K. Expanding the scope of fluorine tags for PET imaging. Science. 2013; 342(6157):429‐430. 2. Hao X, Mingyue S, Ruiyue Z, et al. Developing a cassette microdosing approach to enhance the throughput of PET imaging agent screening. J Pharmaceut Biomed. 2018; 154:48‐56.
Radiolabeled compounds ‐ other medical disciplines and radiopharmacology and cardiology
O-36 | Synthesis and in vivo evaluation of a novel 18F‐labelled PET tracer 18F‐BBR for myocardial perfusion imaging in mice Xiaoai Wu1; Meng Liang2; Rang Wang2; Huawei Cai2; Yyue Chen2; Chengzhong Fan1 1
Sichuan University, China; 2 The Affiliated Hospital of Southwest
Medical University, China
Objectives Cardiovascular‐related diseases have become the leading cause of death and incur significant medical and economic burden worldwide. Myocardial perfusion imaging (MPI) with single‐photon emission computed tomography (SPECT) or positron emission tomography (PET) remains the most effective and noninvasive method to detect and identify the risk index of coronary artery disease (CAD). It can also be used to assess hemodynamic changes and myocardial ischemia. Currently, the most commonly used cardiac PET tracers (e.g., 13NH3 and H215O) presented certain disadvantages in clinical applications due to the short half‐life of the radio‐isotopes.
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Therefore, substantial efforts have been focused on the development of longer half‐life 18F‐labeled PET perfusion tracers. Recent studies revealed that a traditional Chinese medicinal herb, Rhizomes of Coptis chinensis, inhibited acetylcholinesterase (AChE), activated the AMP‐activated protein kinase, and exhibited efficacy in treating congestive heart failure. The aim of this study was to develop a derivative of the main active extract of Coptis chinensis, berberine (BBR) to evaluate its therapeutic potential, and to radiolabel the compound with 18 F to assess the potential of 18F‐BBR as a novel MPI agent. Methods The precursor and reference standard for 18F‐BBR were synthesized from berberrubine through a nucleophilic substitution. 18F‐BBR was labeled with K18F following the methods adapted from the literature. In vitro stability of 18F‐BBR in human serum was measured at 37°C. Cell uptake was assessed in cardiomyocyte H9c2 and fibroblast NIH/3T3 cell lines. Ex vivo biodistribution study was carried out in mice. PET imaging was also conducted to evaluate the pharmacokinetic and binding characteristics of the radiotracer in mice. Results The precursor and reference standard of 18F‐BBR was successfully synthesized. 18F‐BBR was produced in ~30% radiochemical yield (decay uncorrected), greater than 99% radiochemical purity, and molar activity of 6.5 ± 2.1 GBq/μmol (n = 3) at the end of synthesis (EOS). 18F‐BBR displayed high stability in human serum in vitro and maintained >98% radiochemical purity at 6 h after EOS. Cellular uptake assays demonstrated selective uptake of 18F‐BBR in cardiomyocyte H9c2 cells and no uptake in fibroblast NIH/3T3 cells. In biodistribution studies in mice 18F‐BBR displayed extremely high and sustained myocardial uptake with 34.6 ± 3.9, 31.6 ± 2.2, and 30.1 ± 0.2 %ID/g, respectively, at 5, 30, and 240 min post‐injection (n = 4). Heart‐to‐lung and heart‐ to‐liver activity ratios were also high, at 25 ± 1.2 and 2.7 ± 0.2, respectively, at 5 min post‐injection (n = 2). PET imaging with 18F‐BBR showed clear and sustained cardiac uptake in mice, with minimal activity in the lungs and rapid clearance from the liver. Conclusion 18 F‐BBR was successfully synthesized. It exhibited high stability in human serum and selective uptake in cardiomyocyte cells in vitro. PET imaging studies in healthy mice indicated that 18F‐BBR had high and persistent cardiac uptake over 2 h, with high myocardium‐to‐lung and myocardium‐to‐liver ratios. Taken together, results from the current study indicate that 18F‐BBR holds promise as a new radiotracer for myocardial perfusion imaging.
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Radiolabeled compounds ‐ other medical disciplines and radiopharmacology and cardiology O-37 | Exclusive kidney accumulation of DNA origami nanostructures protects kidneys from acute injury Dawei Jiang1; Dalong Ni1; Weijun Wei2; Lei Kang3; Jonathan Engle4; Weibo Cai1 1
University of Wisconsin‐Madison, USA; 2 Shanghai Jiao Tong University
Affiliated Sixth People's Hospital, China; 3 Peking University First Hospital, China; 4 Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
Objectives DNA nanotechnology has been developed for over three decades, and most researchers envisioned the broad potential of DNA origami nanostructures (DONs) for in vivo application due to their biocompatibility and biodegradability. However, the biological behavior of DONs
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in vivo has not been fully understood, let alone exploiting DONs for preclinical or clinical uses. Here, we report the biological behaviors of DONs in mouse and conclude that DONs can be used for the treatment of acute kidney injury (AKI). Methods We radiolabeled three different DONs (Rectangular DON, Rec‐DON; triangular DON, Tri‐DON; and tubular DON, Tub‐DON) with copper‐64 and used positron emission tomography (PET) to investigate their pharmacokinetics and biodistribution patterns in vivo. Then, we induced AKI in healthy mice with an injection of 50% glycerol intramuscularly. And Rec‐DONs were administrated as a test drug to protect kidneys at 2 hours after AKI induction. Phosphate buffered saline (PBS) was used as a control. 24 hours after AKI induction, a 30 min PET imaging with 68Ga‐EDTA (a clinically‐used PET tracer for renal function) was performed for all mice (healthy group, Rec‐DON‐treated group, and PBS‐treated group) to non‐invasively evaluate kidney functions of all groups, then blood and kidney samples were collected for further validating of the treatment effect.
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Results Based on the PET imaging of different DONs, we found that they were all prone to accumulate in the kidneys, with minor uptake in the liver and intestine. Among all three DONs investigated, Rec‐DONs presented the highest kidney uptake. As for the treatment of AKI, we found that the excretory function of AKI mice could be re‐established by administrating Rec‐DONs at 2 h after AKI induction based on the PET imaging with 68Ga‐ EDTA, while PBS could not improve the renal excretion of 68Ga‐EDTA in AKI mice, suggesting the active protection of Rec‐DONs for the kidneys. Blood tests of end products of nitrogen metabolism (urea and creatinine) showed that PBS group had a high level of blood urea nitrogen (BUN) as well as creatinine (Cr), while healthy mice and Rec‐DON‐treated AKI mice both exhibited low BUN and Cr level. H&E staining of kidney tissue sections revealed a large number of casts (destroyed kidney tubules and glomerulus structures) in the PBS group, while no casts could be found in the healthy group, and few in the Rec‐DON‐treated group. Conclusion This is the first study to achieve therapeutic effects with DNA origami nanostructures in murine acute kidney injury model. Our PET imaging results showed that DONs mainly localized in the kidneys, with low uptake in the liver and intestine. With the murine model, Rec‐DONs could significantly improve the excretory function of kidneys with AKI. The therapeutic effects of these DONs in various other diseases are being investigated.
Radiolabeled compounds ‐ oncology (imaging) session 2 O-38 | Development of the first 18F‐labeled MCT1/MCT4 lactate transport inhibitor: Radiosynthesis and preliminary in vivo evaluation in mice Masoud Sadeghzadeh1; Rares Moldovan2; Barbara Wenzel1; Mathias Kranz1; Winnie Deuther‐Conrad1; Magali Toussaint1; Steffen Fischer3; Friedrich‐Alexander Ludwig4; Rodrigo Teodoro2; Sravan Jonnalagadda5; Shirisha Jonnalagadda5; Lester Drewes5; Peter Brust1 1
Helmholtz‐Zentrum Dresden‐Rossendorf, Germany; 2 Institute of
Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum Dresden Rossendorf, Germany; 3 HZDR, FS Leipzig, Germany; 4 Department of Neuroradiopharmaceuticals, Institute for Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum Dresden‐Rossendorf, Research Site Leipzig, Germany; 5 University of Minnesota Duluth, USA
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Objectives Although lactate is occasionally considered as a waste product in physiological cell metabolism, it is also known as an important substrate that fuels the oxidative metabolism of oxygenated tumor cells. Therefore, tumor cells express a set of plasma membrane transporters for lactic acid. Those monocarboxylate transporters (MCTs) are regarded as functional biomarkers for the metabolic symbiosis between glycolytic and oxidative tumor cells [1]. Overexpression of MCT1 and MCT4 has been shown for a variety of human cancers (e.g., colon, brain, breast, and kidney) [2]. Experimentally, inhibition of MCT1/MCT4 results in intracellular lactate accumulation, acidosis and cell death. In the current study, the first 18F‐labeled MCT1/MCT4 inhibitor was developed for potential in vivo imaging of MCT expression in cancer. Methods Fluorinated α‐CHC derivatives (FACH and tert‐Bu‐ FACH) were synthesized and the inhibitory activity of FACH towards MCT1 and MCT4 was estimated by [14C]lactate uptake assays using immortalized rat brain endothelial (RBE4) and MDA‐MB‐231 cell lines, respectively. For the radiosynthesis of [18F]FACH, a protected mesylate precursor was developed to prevent any possible effect on the labeling reaction. [18F]FACH was produced via a two‐step radiosynthesis approach, starting with the nucleophilic substitution on the alkyl chain using [18F] TBAF followed by removal of the protecting group by trifluoroacetic acid (TFA) at room temperature (Figure 1A). Figure 1. (A) Radiosynthesis of [18F]FACH; (B) Small animal PET image (0‐60 min) of a female CD‐1 mouse depicting the differential distribution of [18F] FACH in peripheral organs in particular in kidney medulla and cortex (blue cross). Separation of [18F]FACH was performed by semi‐preparative HPLC (Reprosil‐Pur C18‐AQ column, 250 × 10 mm, 46% CH3CN/aq. 20 mM NH4HCO2, pH = 4‐5, flow 3.5 mL/min). The tracer was finally purified via solid‐phase extraction (Sep‐Pak® C18 light cartridge) and formulated in 10% EtOH/saline solution. In vitro stability tests were performed in pig plasma, saline, PBS, and n‐octanol. The logD value was assessed by the shake‐flask method. The in vivo metabolism of the radiotracer was investigated in female CD‐1 mice at 30 min p.i. The biodistribution of [18F]FACH and the inhibitory effects of FACH and α‐CHC were investigated by dynamic PET imaging (60 min, nanoScan® PET/MRI, MEDISO, Budapest, Hungary) of female CD‐1 mice (Figure 1B). Results FACH showed strong inhibition of MCT1 and MCT4 (IC50 = 11.0 and 6.4 nM, respectively). The intermediate [18F]tert‐Bu‐FACH was obtained by an optimized
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procedure (CH3CN, 3.75 μmol of TBAHCO3, 2‐5 GBq of K[18F]F, 100°C, 15 min) with 55‐85% radiochemical yield (n = 10, non‐isolated). [18F]FACH was obtained after deprotection of [18F]tert‐Bu‐FACH with TFA in acetonitrile at room temperature for 15 min. After purification and formulation, the novel radiotracer could be achieved with a RCY of 39 ± 3% (n = 10, EOB), molar activity of 42‐100 GBq/μmol (EOS), and RCP >98%. The measured logD value (0.42) reveals moderate lipophilicity of the radiotracer. [18F]FACH was highly stable in saline (>98%) up to 60 min. In vivo metabolite studies showed >98% of intact tracer in plasma, brain, liver and kidney at 30 min p.i. Beside [18F]FACH, a few polar metabolites were also found in urine after 30 min p.i. The organ distribution pattern of [18F]FACH in healthy mice corresponds to the specific expression of MCT1 and MCT4 in kidney, lung, pancreas, and liver. In these tissues, a moderate to high reduction of uptake was observed after pre‐ injection of FACH and α‐CHC, respectively. Conclusions The high uptake of [18F]FACH in kidney and other peripheral MCT‐expressing organs together with the strong inhibition by specific drugs provide evidence that the new MCT1/MCT4‐targeting radiotracer could be proven in ongoing studies to be useful for imaging of solid tumors with PET.
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ACKNOWLEDGEMENT The Alexander von Humboldt Foundation and the University of Minnesota Foundation are acknowledged for their financial support. RE FER EN CES 1. Halestrap, A. P. Mol. Aspects Med.2013, 34, 337‐349 2. Pinheiro, C. et al. J BioenergBiomembr.2012, 44, 127‐139.
Radiolabeled compounds ‐ oncology (i ma gi ng ) s es si o n 2 O-39 | Preclinical evaluation of 99mTc‐labeled anti‐EpCAM nanobody conjugates for imaging EpCAM receptor expression by immuno‐SPECT Tianyu Liu1; Yue Wu1; Linqing Shi2; Yanpu Wang3; Hannan Gao4; Biao Hu4; Xin Zhang2; Huiyun Zhao1; Yakun Wan5; Bing Jia4; Fan Wang4 1
Medical Isotopes Research Center and Department of Radiation
Medicine, Peking University, China; 2 Medical Isotopes Research Center and Department of Radiation Medicine, China; 3 Medical Isotopes Research Center, Peking University, China; 4 Peking University, China; 5
CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia
Medica, China
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Objectives Overexpression of epithelial cell adhesion molecule (EpCAM) plays important roles in tumor genesis and tumor progression in almost all epithelial‐derived cancer. Monitoring of EpCAM in tumors might provide guidance for tumor evaluation, treatment, and prognosis. In this study, we describe the synthesis and evaluation of a site‐ specific 99mTc‐labeled stable EpCAM‐targeting nanobody (NB4) as a SPECT radiotracer for the in vivo imaging of EpCAM expression.
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Methods High specific activity precursor 99mTc‐G4K was obtained by labeling the polypeptide GGGGK‐HYINIC with 99mTc, in which TPPTS and tricine acted as co‐ligands. Subsequently, under the action of Sortase A enzyme, 99mTc‐ G4K was site‐specific fixed on the C‐terminal of the ‐ LPETG containing nanobody (NB4), and 99mTc‐NB4 was obtained accordingly. The in vitro stability, specificity, and cellular metabolic properties of 99mTc‐NB4 were evaluated by detailed in vitro experiments. The tumor imaging
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ability of 99mTc‐NB4 in EpCAM positive and negative tumors bearing mice was evaluated by in vivo SPECT/CT imaging. Finally, the pharmacokinetic data of 99mTc‐NB4 was obtained by in vitro biodistribution experiments. Results 99m Tc‐NB4 displayed high EpCAM specificity both in vitro and in vivo. SPECT/CT imaging revealed that 99m Tc‐NB4 was cleared rapidly from the blood and normal organs except for the kidneys, and HT‐29 tumors were clearly visualized in contrast with HL‐60 tumors. The uptake value of 99mTc‐NB4 in HT‐29 tumors was increased continuously from 3.77 ± 0.39 %ID/g at 0.5 h to 5.53 ± 0.82 %ID/g at 12 h after injection. Conclusion 99m Tc‐NB4 is a promising SPECT radiotracer for the noninvasive imaging of EpCAM expression in vivo. Our data support that this site‐specific radiolabeling tracer has high stability and high activity for 1‐day imaging.
Radiolabeled compounds ‐ oncology ( i m a g i n g ) se s s i o n 2 O-40 | PET imaging of human melanoma using a novel 18F‐labeled dual AmBF3 derivative of alpha‐melanocyte stimulating hormone Chengcheng Zhang1; Zhengxing Zhang1; Kuo‐Shyan Lin1; Helen Merkens2; Jutta Zeisler1; Nadine Colpo1; David Perrin3; Francois Benard1 1
BC Cancer Research Centre, Canada; 2 Department of Molecular
Oncology, BC Cancer Agency, Vancouver, BC, Canada; 3 Department of Chemistry, University of British Columbia, Canada
Objectives Molecular imaging of human melanoma targeting melanocortin‐1 receptor (MC1R) is a challenging task due to limited expression level of the receptor (~1000 MC1R/cell). We recently developed an 18F‐labeled ammoniomethyl‐trifluoroborate (AmBF3)‐conjugated alpha‐melanocyte stimulating hormone (αMSH) derivative (CCZ01064), and acquired high contrast images of mouse melanoma (~22,000 MC1R/cell) with positron emission tomography (PET) [1]. The aim of this study was to evaluate the potential of CCZ01064, as well as a novel dual AmBF3 derivative CCZ01096 (Figure 1A), for human melanoma imaging in a preclinical animal model using PET. Methods Both CCZ01064 and CCZ01096 were synthesized using standard Fmoc chemistry and purified using high
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performance liquid chromatography (HPLC). Competitive binding assays were performed using B16F10 cells with 125I‐NDP‐αMSH as the radioligand. The 18F‐labeling was achieved in a simple one step 18F‐19F isotope exchange reaction in mild conditions (pH 2). The 18F‐ labeled peptides were purified using HPLC. Saturation binding assays were performed using human melanoma SK‐MEL‐1 cells with 125I‐NDP‐αMSH. PET imaging and biodistribution studies were performed in NSG mice bearing SK‐MEL‐1 tumors. Results Both CCZ01064 and CCZ01096 were prepared in high purity. Sub‐nanomolar binding affinity (Ki = 0.51 ± 0.08 nM) was achieved for CCZ01096 (Figure 1B). Radiolabeling with 18F for both CCZ01064 and CCZ01096 were readily achievable in decay‐corrected radiochemical yield of 14.3 ± 4.9 and 29.2 ± 4.6%, respectively. The dual AmBF3‐conjugated [18F]F‐CCZ01096 resulted in superior molar activity of 193.6 ± 73.5 MBq/nmol, in comparison to 78.6 ± 21.0 MBq/nmol of [18F]F‐CCZ01064. The MC1R receptor density on SK‐MEL‐1 cells was determined to be 972 ± 154 receptors/cell (n = 4). SK‐MEL‐1 human melanoma was clearly visualized at both 1 and 2 h post‐injection (p.i.) using [18F]F‐CCZ01096 with minimal background activity accumulation except for kidney, bladder, and thyroid (Figure 1C). With a lower molar activity, SK‐MEL‐1 melanoma was distinctly visualized at 2 h p.i., but not at 1 h p.i. for [18F]F‐CCZ01064, and overall lower tumor‐to‐ normal organ contrast was observed (Figure 1D). Biodistribution studies were also carried out and showed consistent results to PET imaging. Tumor uptake of 5.44 ± 0.90 and 6.46 ± 1.42 percent injected dose per gram of tissue (%ID/g) at 1 and 2 h p.i. was achieved for [18F]F‐ CCZ01096, respectively (n = 5). High tumor‐to‐normal organ contrast ratios were observed at 2 h p.i., i.e., tumor‐ to‐blood at 30.6 ± 5.7 and tumor‐to‐muscle at 85.7 ± 11.3. In comparison, lower tumor uptake of 2.71 ± 0.55 and 3.05 ± 0.47%ID/g at 1 and 2 h p.i. was achieved for [18F]F‐ CCZ01064, respectively. Also, lower tumor‐to‐normal organ contrast was observed at 2 h p.i., i.e. tumor‐to‐blood at 13.8 ± 6.2 and tumor‐to‐muscle at 33.7 ± 14.9. In addition, blocking experiments were performed with co‐ injection of excess amount of non‐radioactive counterparts for both PET imaging and biodistribution studies, and resulted in significant tumor uptake reduction (≥85%), suggesting the uptake was MC1R‐mediated. Conclusions We evaluated two 18F‐labeled αMSH derivatives for PET imaging of human melanoma. Due to the limited number of MC1R, the dual AmBF3 moieties enabled high molar activity and led to high contrast PET images of human melanoma using [18F]F‐CCZ01096 in a preclinical model of mice bearing SK‐MEL‐1 tumors.
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FIGURE 1 (A) Chemical structure of the dual AmBF3‐conjugated αMSH derivative, CCZ01096. (B) Representative competitive binding curve for CCZ01096. Maximum intensity projections of PET images with [18F]F‐CCZ01096 (C) and [18F]F‐CCZ01064 (D) acquired at 1 and 2 h post‐injection (p.i.), as well as 1 h p.i. blocked with co‐injection of excess non‐radioactive counterparts in mice bearing SK‐MEL‐1 human melnaoma xenografts. Color bar unit is %ID/g. t, tumor; k, kidney; i, intestines; th, thyroid; b, bladder.
ACKNOWLEDGMENTS The authors would like to thank Dr. Jinhe Pan, Wade English, Baljit Singh, and Guillaume Langlois for technical assistance.
2
Physiology I, Institute of Physiology, Eberhard Karls University of Tübingen, Germany; 4 Werner Siemens Imaging Center, Germany; 5
R EF E RE N C E S 1. Zhang C, Zhang Z, Lin K‐S, et al. Mol. Pharmaceutics, 2018, 15 (6), 2116–2122.
R a d i o l a b e l e d C o m p o u n d s ‐ O nc o l o g y ( I ma g in g ) S e ss io n 2 O-41 | Imaging of in vivo tumor senescence with a novel beta‐galactosidase specific PET tracer Jonathan Cotton1; Benyuan Zhou1; Johannes Schwenck2; Katharina Wolter3; Anna Kuehn4; Kerstin Fuchs4; Gerald Reischl5; Andreas Maurer1; Christian la Fougère2; Lars Zender6; Marcel Krueger1; Bernd Pichler4 1
Werner Siemens Imaging Center, Department of Preclinical Imaging and
Radiopharmacy, Eberhard Karls University of Tübingen, Germany;
Department of Nuclear Medicine and Clinical Molecular Imaging,
Eberhard Karls University of Tübingen, Germany; 3 Department of
University Hospital Tübingen, Germany; 6 Department of Internal
Medicine VIII, University Hospital Tübingen, Germany
Objectives Senescence, a durable cell cycle arrest, is a stress response that plays essential role in the treatment outcome in cancer. Currently, senescence‐associated ß‐galactosidase (SABG) is the gold standard biomarker for ex vivo detection of senescence and is used primarily in ex vivo histology. To address the need for the in vivo detection and quantification of senescent cells in cancer patients, we have developed the GMP compliant PET tracer [18F] FPyGal. Methods The automated GMP synthesis relies on nucleophilic aromatic fluorination, producing an acetylated ß‐galactoside intermediate, which is deprotected in the module reactor with dilute NaOH. Purification by semipreparative HPLC uses an eluent that is suitable for injection. LogP of the
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tracer was obtained experimentally using a PhosphorImager and was compared to predicted values. Enzyme specificity was assessed by incubating the tracer/standard with ß‐galactosidase and evaluated using 1H NMR and radio‐HPLC. In vitro, senescence was induced in HCT116 cells by a single treatment of doxorubicin and in a liver progenitor cell line it was induced by p53‐ reactivation. In two hepatocellular carcinoma (HCC) cell lines, a ribosomal checkpoint inhibitor (RCI) was used for senescence induction. The tracer uptake was subsequently assessed using a gamma‐counter. For in vivo experiments, the previously described cell lines were injected s.c. in mice. For senescence induction, the animals were suitably treated with doxorubicin, doxycycline or RCI. The tracer was injected i.v., after which PET/MR scans were performed. The tracer uptake in the tumors (%ID/cc) and tumor‐to‐muscle ratios were calculated. Ex vivo tumor sections were subjected to autoradiography followed by SABG staining to correlate tracer uptake with ß‐galactosidase activity. Finally, correlative immunohistochemistry against biomarkers for senescence (p53, p16), apoptosis (caspase‐3) and cellular proliferation (ki67) was performed. Both a toxicity (rat) and pilot first‐in‐man studies were performed. In the latter, the tracer was applied in a colorectal cancer patient with liver metastases treated with senescence inducing Alisertib. Results The decay corrected yield was 18.6 ± 2.5% (n = 10; EOB), with a molar radioactivity of 98.1 ± 23.4 GBq*μmole−1 (n = 5; EOS) and high (>99%) radiochemical purity. The ChemDraw calculated cLogP of −1.6 closely matches observed LogP of −1.4. Incubation of the tracer with ß‐ galactosidase yielded the expected (radioactive) metabolite. In all four cell lines, the in vitro tracer uptake was significantly increased compared to the control cells. The greatest increase was observed in one of the HCC cell lines (by a factor of >3). In vivo, notable tracer uptake was demonstrated in all four tumor models. The highest increase was observed in one of the HCC models, with an increase in tracer uptake by a factor of ~2 compared to non‐ senescent tumors. Ex vivo SABG staining was compared to autoradiography, with regions containing high radioactive signal correlating to higher ß‐galactosidase activity. Finally, immunohistology of tumor tissue supported induction of senescence. The compound passed the toxicology tests and the human study revealed high tracer uptake in a liver metastasis. Conclusions Owing to the low toxicity, the increased uptake of [18F] FPyGal in vitro and in vivo in senescent cells and tumors as well as the promising first‐in‐man study, further clinical trials with the GMP compliant tracer are currently being prepared.
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ACKNOWLEDGEMENTS The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007‐ 2013) /ERC Grant Agreement n. [323196]. RE FER EN CES Campisi J, et. al., Nature Reviews, 2007
Radiolabeled compounds ‐ oncology (i ma gi ng ) s es si o n 2 O-42 | The in vivo and in vitro validation of two activin‐receptor like kinase 5 targeting PET tracers Lonneke Rotteveel1; Alex Poot2; Peter Dijke3; Harm Jan Bogaard4; Adriaan Lammertsma4; Albert Windhorst5 1
Radiology and Nuclear Medicine, Radionuclide Center, Amsterdam
UMC, VU University, Amsterdam, The Netherlands; 2 Amsterdam UMC, VU University, Netherlands; 3 Department of Molecular Cell Biology, Leiden University Medical Centre, Netherlands; 4 Amsterdam UMC, VUmc, Netherlands; 5 VU University Medical Center, Netherlands
Introduction TGFβ plays a complex role in cancer biology is involved in both tumor suppression and promotion. Elevated levels of the TGFβ type I receptor were found in numerous cancers and diseases like pulmonary arterial hypertension and fibrosis.1 Positron emission tomography (PET) imaging of ALK5 would allow assessing its expression and activity in vivo to create an opportunity to study the role of ALK5 in these diseases. Therefore, [11C]LR111 (IC50 = 5.5 nM)2 and [18F]EW‐7197 (IC50 = 13 nM)3 were selected as lead compounds for carbon‐11 and fluorine‐18 labelling, respectively to study their potential to study ALK5 targeting and expression in vivo. Materials and Methods [11C]LR111 and [18F]EW‐7197 were synthesized as previously reported.4 A metabolite analysis was accomplished in SCID mice (n = 4) at 15 and 45 min. The non‐polar metabolite of [11C]LR111 in SCID mice was identified with LC‐MS/MS. Binding experiments with both tracers were established with cell experiments and with TABLE 1 Ex vivo metabolite analysis of [11C]LR111 and [18F] EW‐7197 in blood of healthy SCID mice (n = 4) [11C]LR111
[18F]EW‐7197
15 min
67 ± 2
54 ± 3
45 min
39 ± 2
21 ± 2
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autoradiography on MDA‐MB‐231 tumor sections. Both tracers were used for PET imaging in MDA‐MB‐231 xenograft models. Results and discussion [11C]LR111 was synthesized with a yield of 17 ± 6%, a specific activity of 126 ± 79 GBq.μmol−1 and a purity of >95% (n = 44). [18F]EW‐7197 was synthesized with a yield of 10 ± 5%, a specific activity of 183 ± 126 GBq.μmol−1, and a purity of >95% (n = 11). The metabolic stability which was measured in vivo was moderate; 39 ± 2% of intact [11C]LR111 and 21 ± 2% of intact [18F]EW‐7197 was observed in blood plasma after 45 minutes (Table 1). LC‐MS/MS analysis identified a hydroxylated analog of [11C]LK111. Selective uptake of [11C]LR111 and [18F]EW‐7197 was obtained in MDA‐ MB‐231 cells. The autoradiograms of [11C]LR111 and [18F]EW‐7197 presented selective binding of the tracer to the tumor sections (Figure 1b). The PET images showed selective uptake of both tracers in the MDA‐ MB‐231 tumor xenografts in vivo (Figure 1c). Conclusion [11C]LR111 and [18F]EW‐7197 both show selective binding to the ALK5 receptor in vivo and in vitro and are thereby valuable tools for the diagnostics of ALK5 in vitro and in vivo. ACKNOWLEDGEMENT CVON is acknowledged for funding this project and the BV Cyclotron VU for providing the [11C]CO2 and [18F]F‐ R EF E RE N C E S 1. Massague J, Blain SW et al. 2000, Cell, 103(2):295‐30 2. Amada H, Sekiguchi Y et al. 2012, Bioorganic & Medicinal Chemistry, 20(24),7128‐7138. 3. Jin CH, Krishnaiah M et al. 2014 Journal of Medicinal Chemistry, 57(10):4213‐4238.
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4. Rotteveel L, Poot A.J. et al 2017 ISRS2017
Radiolabeled compounds ‐ oncology (i ma gi ng ) s es si o n 2 O-43 | Molecular imaging of autotaxin: Targeting the crossroad of inflammation and cancer Marcus Litchfield1; Melinda Wuest1; Emmanuelle Briard2; Yves Auberson3; Todd McMullen1; David Brindley1; Frank Wuest1 1
University of Alberta, Canada; 2 Novartis Pharma AG, Switzerland;
3
Global Discovery Chemistry, Novartis Institutes for BioMedical Research,
Switzerland
Objectives Autotaxin (ATX), due to its production of lysophosphatidate (LPA), is an emerging drug target for chronic inflammatory diseases, including pathological states of fibrosis and cancer. As ATX inhibitors are now progressing to the clinic, innovative tools are needed to measure ATX expression and distribution in vivo. Herein, we describe the radiosynthesis and preclinical validation of a 18F‐labeled benzyl‐methyl‐tetrazole [18F]1 as radiotracer for PET imaging of ATX in cancer. Methods Inhibitory potency of the ATX inhibitor 1 was determined by the measurement of released choline from LPC in the presence of ATX1. Radiosynthesis was accomplished through conventional radiofluorination chemistry starting from the corresponding tosylate labeling precursor 2 and n. c.a. [18F]fluoride. Tumor uptake and binding to ATX of
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FIGURE 1 18
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Radiosynthesis (left) and dynamic PET imaging of [18F]1 (right) in 4T1 and 4T1‐LPP1 tumors
F‐labeled ATX inhibitor [18F]1 were studied with dynamic PET imaging in orthotopic murine 4T1 mammary tumors with and without lipid phosphate phosphatase‐1 (LPP1) expression. LPP1 reduces ATX expression in adipose tissue adjacent to 4T1 tumors2. Results Benzyl‐methyl‐tetrazole 1 was identified as highly potent ATX inhibitor (IC50 = 4 nM) in a choline releasing assay. Radiosynthesis of [18F]1, including radio‐HPLC purification, was accomplished in 120 min in isolated radiochemical yields of 63‐70% (n = 7), starting from corresponding tosylate precursor 2 (3 mg) in CH3CN (300 mL) and reaction at 85°C for 5 min. Molar activity (Am) was calculated to be >40 GBq/μmol. Lipophilicity of radiotracer [18F]1 was determined using the shake‐flask method (logP = 1.77). Dynamic PET imaging studies revealed higher radiotracer uptake in 4T1 tumors (SUV60min = 0.81 ± 0.05 (n = 3)) compared to 4T1‐LPP1 tumors with lower ATX expression ((SUV60min = 0.69 ± 0.07 (n = 3)) confirming ATX‐mediated uptake of radiotracer [18F]1 (Figure 1). Conclusions Radiotracer [18F]1 is the first example of a 18F‐labeled ATX inhibitor used for PET imaging of ATX. Future studies will include use of human cancer cells with high ATX baseline expression such as thyroid cancer cell line 8305C3. ACKNOWLEDGEMENTS The authors gratefully acknowledge the Dianne and Irving Kipnes Foundation, the Alberta Cancer Foundation,
and the University of Alberta Faculty of Medicine and Dentistry for supporting this work. RE FER EN CES 1. Rosse G. ACS Med. Chem. Lett. 2006, 7, 1016‐1017. 2. Tang X. et al., J. Lipid Res. 2014, 2389‐2399. 3. Benesch M.G. et al. Endocr. Relat. Cancer. 2015, 22, 593‐607.
Keynote l ecture 4 O-44 | Engineered antibodies—New possibilities for brain PET Stina Syvanen Uppsala University, Sweden
Objectives Traditionally PET radioligands for brain imaging are based on small drug‐like and fairly lipophilic molecules. Antibodies are large molecules with low and slow brain distribution and have therefore not been used for brain PET. However, antibodies can be designed for more efficient passage across the blood‐brain barrier (BBB) into the brain parenchyma. This strategy has been used in a number of preclinical studies1–3, and some clinical trials4, to shuttle therapeutic antibodies across the BBB
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for treatment of neurodegenerative diseases. In line with this, we are exploring the possibility to use antibody‐ based radioligands, of different formats and sizes, for PET imaging of aggregated proteins in preclinical models of Alzheimer's disease (AD) and Parkinson's disease (PD) pathology. Methods Antibodies, or fragments of antibodies, targeting amyloid‐ beta (Aβ) or alphasynuclein (α‐syn), were fused with either transferrin receptor (TfR) antibody 8D35 or fragments of 8D3 resulting in bispecific antibodies of different formats and sizes. Generation of bispecific antibodies targeting Aβ protofibrils, i.e., aggregates formed prior to insoluble Aβ plaques, i.e., the pathological hallmark of AD, has been a special focus of our research and thus, protofibril selective antibody mAb1586 has been extensively used. The humanized form of mAb158, BAN2401, is presently studied in clinical phase III studies, as a therapeutic for AD7. The bispecific antibodies were then labeled with iodine‐ 124 (124I) and used for PET imaging in AD models and wild‐type mice of different ages. Binding to TfR via the 8D3 binding domain enables receptor mediated transcytosis across the BBB while the mAb158‐moiety binds to Aβ in the brain parenchyma (Figure 1). Initial work to radiolabel bispecific antibodies with fluorine‐18 has also been initiated, as well as the construction of bispecific antibodies targeting aggregated α‐syn, i.e. the protein believed to cause neuronal death in PD. Results All TfR binding bispecific antibodies displayed up to 80‐ fold better BBB transport compared to their unmodified version without the TfR‐moiety8–11. Monovalent binding to TfR resulted in more efficient transport across the
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BBB compared with bivalent TfR binding and smaller molecular size of the final bispecific protein resulted in faster elimination from blood and peripheral organs, thus making the smaller constructs better suited for further development as PET radioligands. PET images obtained after administration of radiolabeled bispecific antibodies showed a clear distinction between AD models and wild‐type control mice. The PET signal correlated closely with levels of Aβ protofibrils measured in brain homogenate. Initial experiments show that flourine‐18 labelling can be achieved by trans‐cyclooctene (TCO) modification of the bispecific antibodies and subsequent reaction with [18F]fluorotetrazines. Conclusions Aggregated proteins in the brain can be visualized in vivo with bispecific antibodies engineered to enter the brain. In a longer perspective, the use of bispecific antibodies as PET ligands may enable imaging of proteins involved in diseases of the brain for which imaging agents are lacking today.
RE FER EN CES 1. Yu YJ, et al. Sci Transl Med. 2011.3:84 2. Yu YJ, et al. Sci Transl Med. 2014.6:261 3. Niewoehner J, et al. Neuron. 2014.81:49‐60 4. Giugliani R, et al. Orphanet J Rare Dis. 2018.13:110 5. Kissel K, et al. Histochem Cell Biol 1998.110:63‐72 6. Englund H, et al. J Neurochem. 2007.103:334‐45 7. Logovinsky V, et al. Alzheimers Res Ther. 2016.8:14 and for recent phase IIb results: https://www.eisai.com/news/2018/ news201866.html 8. Sehlin D, et al. Nature Commun. 2016.7:10759
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9. Hultqvist G, et al. Theranostics 2017; 7(2):308‐318 10. Syvänen S, et al. Neuroimage. 2017.148:55‐63 11. Fang XT, et al. Neuroimage. 2019 184:881‐888.
R a d i o c h e m i s t r y ‐ ot he r r a d i o n u c l i d e s a n d ta r g e t r y O-45 | Toward Auger radiotherapy with rhodium‐103mRh: Bifunctional 16aneS4 chelator synthesis and development of a rhodium‐ 103m Rh generator Charlotte Magnus1; Gregory Severin2; Fedor Zhuravlev3; Ulli Köster4; Jesper Fonslet3; Mikael Jensen3; Andreas Jensen1 1
DTU Nutech, Technical University of Denmark (DTU), Denmark;
2
Technical University of Denmark, Denmark; 3 Center for Nuclear
Technologies, Technical University of Denmark, Denmark; 4 Institut Laue‐ Langevin, France
Objective Auger electron emitters represent an attractive modality for radionuclide therapy. Auger electrons have short ranges of less than a cell diameter and high energy deposition. Small tumors lesions, such as micro metastases, can therefore be targeted while sparing surrounding healthy tissue. Rhodium‐103m (103mRh, t½ = 56.1 min) has been identified as a very promising therapeutic Auger electron emitter due to its high electron‐to‐photon yield.1 103mRh can be obtained as the decay daughter of Palladium‐103 (103Pd, t½ = 17 days).2 Macrocyclic thioethers have
FIGURE 1
Synthesis of 16aneS4‐ol and derivatives.
previously been found to form strong chelates with rhodium.3 Here, we present our efforts to synthesize bifunctional macrocyclic chelator for 103mRh, based on the 16aneS4 ring. Further, we hypothesized that the decay of chelated 103Pd would result in the expulsion of radiochemically pure 103mRh. We utilized this principle in the development of a radionuclide generator for 103mRh. Methods The macrocyclic thioether 16aneS4‐ol (5) was synthesized in five consecutive steps (Figure 1). The linear diol (1) was prepared in quantitative yield. By tosylation and conversion of (2), compound (3) was obtained in 97% yield. Finally, deprotection of (4) with subsequent ring‐closing gave the macrocyclic thioether‐alcohol (5) as the final product in excellent purity and 50% yield. Compound (5) offered functionality for further modification. The oxo‐ butanoic acid derivate (6) was formed in one‐step in 74% yield. Compound (7) was formed from octanol mesylate and compound (5) in excellent purity and 40% yield. Compound (6) was conjugated to human epidermal growth factor (hEGF) using EDC and NHS. [103Pd]Pd was obtained by neutron irradiation of enriched [102Pd]Pd. The targets were dissolved in aqua regia, followed by reconstitution in hydrochloric acid. The [103Pd]Pd was then chelated by compound (7) in excess. The chelate was applied to a C18 solid support, which was eluted with hydrochloric acid. Eluates were analyzed by liquid scintillation and X‐ray spectrometry. Results We synthesized 16aneS4‐ol, and this was further functionalized into compound (6). Preliminary studies show that (6) has been conjugated to hEGF. hEGF is an
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internalizing and nucleus‐localizing small protein that was recently used in phase I clinical studies.4 To achieve efficient therapy, Auger decays must occur near the DNA, making internalization paramount. [103Pd]Pd was successfully chelated by compound (7) and captured on a C18 solid support. By eluting with aqueous hydrochloric acid (1.0 M), radiochemically pure (RCP: >99%) could be obtained. Maximum effective molar activities were 23 MBq/nmol, decay‐corrected to dissolution of the target. Elution yields, as percentage of theoretical maximum, were generally modest at about 5%. It has been previously calculated that recoil energy alone would not be sufficient for Szillard‐Chalmers based expulsion.5 We suggest that transient ionization of the daughter may play a role in the observed expulsion, but that this may not be sufficient to achieve near quantitative elution yields. Conclusion We successfully synthesized bifunctional derivatives of the 16aneS4‐ol chelator and conjugated these to a nucleus‐localizing vector (hEGF). In addition, we developed a practical generator capable of furnishing 103m Rh in high radiochemical purity, although in modest yields. We will continue this work through optimization of both technologies, as well as combining the two into therapeutically effective 103mRh‐based Auger radiotherapeutics. ACKNOWLEDGMENTS This work was funded by The Independent Research Fund Denmark (DFF). R EF E RE N C E S 1. Bernhardt, P. et al. Acta Oncol. (Madr). 40, 602–608 (2001). 2. Bartoś, B. et al. Radioanal. Nucl. Chem. 279, 655–657 (2009). 3. Li, N. et al. Nucl. Med. Biol. 24, 85–92 (1997). 4. Vallis, K. A. et al. Am J Nucl Med Mol Imaging 4, 181–92 (2014). 5. van Rooyen J, et al. Applied Radiation and Isotopes 66, 1346–1349 (2008).
R a d i o c h e m i s t r y ‐ ot he r r a d i o n u c l i d e s a n d ta r g e t r y O-46 | Synthesis of precursors for
211
At‐
labelling of anti‐PSMA HuJ591 mAb and stability comparison after in vitro cellular internalization Aurélia Roumesy1; Stébastien Gouard1; Laurent Navarro1; Faustine Lelan1; Ferid Haddad2; Francois Guérard3; Alain Faivre‐Chauvet; Michel Chérel4; Jean‐Francois Gestin4 1
CRCINA, France; 2 GIP ARRONAX, France; 3 CRCINA, Inserm, CNRS,
Nuclear Oncology Group, France; 4 CRCINA, Inserm, CNRS, France
Objectives Radio‐immunotherapy (RIT) is a promising approach for cancer treatment because curative doses of radiation can potentially be selectively delivered not only to the primary tumour but also to metastatic lesions spread throughout the body. A radionuclide of great interest for RIT is the heavy halogen 211At because it decays by the emission of short‐range, high‐energy α‐particles. Based on its electrophilic At+ form, several approaches using the astatodestannylation reaction of aryl precursors have been developed in order to attach 211At to biomolecules.1 Many prosthetic groups have been synthesized for biomolecule labelling with 211At, in order to reinforce the stability of 211 At‐biomolecule bond.2,3 Various improvements have been described but they all exhibit some in vivo instability when the radiopharmaceutical is rapidly metabolized or when it is internalized in the tumour cell. However, no direct comparison between these reported compounds has been reported. Thus, the aim of this work was to compare the stability of some of prosthetic groups coupled to antibodies by acylation of lysine amino group but also to study the influence of a maleimide function for addition to thiol functions. We report herein the comparison of four astatinated prosthetic groups that have been associated to internalizing anti‐PSMA HuJ591 mAb through activated ester (NHS) or maleimide function and tested in the same in vitro test model. Methods Three NHS based precursors (MeATE, SPEMS and SGMTB) and a maleimide precursor (SMPM) were synthesized in order to compare the influence of the stability of the At‐C bond or of the prosthetic group‐Ab bound. They were radiolabelled with 125I and 211At and then coupled to the internalizing IgG anti‐PSMA HuJ591 mAb via their NHS or maleimide function. To compare the stability of these four compounds, an in vitro cellular internalization assay was conducted with LNCaP‐GFP cell line to measure the percentage of radioactivity dissociated from the IgG present in the extracellular medium after internalization. Results All precursors (MeATE, SPEMS, SGMTB, and SMPM) were synthesized and obtained with high purity. Radiolabelling of precursors with 125I gave radiochemical yields (RCYs) for [125I]SIB, [125I]Methyl‐SIP, [125I]SGMIB, and [125I]IMPM of 51, 63, 56, and 50%, respectively. Radiolabeling with 211At gave RCYs for [211At]SAB, [211At]Methyl‐SAPS, [211At]SAGMB, and [211At]AMPM of 48, 20, 14, and 31, respectively. Radiolabeling of J591 mAb with [125I]SIB, [211At]SAB, [125I]Methyl‐SIPS, [211At]Methyl‐SAPS, [125I]SGMIB, and [211At]SAGMB through the NHS function provided conjugation yields within the 45‐60% range, providing the purified radiolabeled antibody with a >95% radiochemical purity.
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Radiolabeling of J591 mAb with [125I]IMPM and [211At] AMPM through the maleimide function provided conjugation yields within the 80‐90% range, providing the purified radiolabeled antibody with a >95% radiochemical purity. Internalization tests performed with either 125I‐ radiolabeled compounds [125I]SIB, [125I]Methyl‐SIPS, [125I]SGMIB, and [125I]IMPM, or 211At‐radiolabelled compounds [211At]SAB, [211At]Methyl‐SAPS, [211At]SAGMB, and [211At]AMPM showed no significant differences even if we observed a little advantage to the maleimide coupling function. Conclusion Under the conditions of our experiment (with IgG HuJ591 and LNCaP‐GFP cell line), all tested 125I or 211 At radiolabelled compounds exhibited some instability after internalization but no significant differences where observed. ACKNOWLEDGMENTS This research was supported in part by grants from the French National Agency for Research, called “Investissements d'Avenir” IRON Labex no. ANR‐11‐ LABX‐0018‐01 and ArronaxPlus Equipex no. ANR‐11‐ EQPX‐0004, and by grant INCa‐DGOS‐Inserm_12558. R EF E RE N C E S 1. Guérard, F., Gestin, J.‐F. & Brechbiel, M. W. Production of [211At]‐ astatinated radiopharmaceuticals and applications in targeted α‐particle therapy. Cancer Biother.Radiopharm. 28, 1–20 (2013). 2. Vaidyanathan, G., Affleck, D. J., Bigner, D. D. & Zalutsky, M. R. N‐succinimidyl 3‐[211At]astato‐4‐guanidinomethylbenzoate: an acylation agent for labeling internalizing antibodies with alpha‐ particle emitting 211At. Nucl. Med. Biol. 30, 351–359 (2003). 3. Talanov, V. S. et al. Preparation and in vivo evaluation of a novel stabilized linker for 211At labeling of protein. Nucl. Med. Biol. 33, 469–480 (2006).
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R a d i o ch e m i s t r y ‐ o t h e r r a d i o n u c l i d e s an d t a r g e t r y O-47 | Radiosynthesis of a novel 77Br‐labeled PARP‐1 inhibitor through Cu‐mediated aryl boronic ester bromination Paul Ellison1; Jennifer Burkemper2; Aeli Olson3; Sabrina Hoffman1; Sean Reilly4; Mehran Makvandi4; Robert Mach5; Todd Barnhart1; Suzanne Lapi6; Jonathan Engle7 1
University of Wisconsin, USA; 2 Department of Radiology, University of
Alabama, Birmingham School of Medicine, USA; 3 Department of Medical Physics, University of Wisconsin, USA; 4 Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, University of Pennsylvania, Perelman School of Medicine, USA; 5 University of Pennsylvania, USA; 6
University of Alabama at Birmingham, USA; 7 Department of Medical
Physics, University of Wisconsin School of Medicine and Public Health, USA
Objectives The radioisotopes of bromine include diagnostic positron‐ emitter 76Br (t1/2 = 16.2 h) and therapeutic Auger‐ emitters 77Br (t1/2 = 57.0 h) and 80mBr (t1/2 = 4.4 h), which can be readily and stably incorporated into biological small molecules1. Recently, radiobromine's chemical lability in Cu‐mediated nucleophilic reactions with aryl boronic ester precursors was demonstrated and used for the synthesis of a 77Br‐labeled inhibitor of the DNA damage response protein, poly ADP ribose polymerase (PARP‐1) derived from the cancer therapeutic olaparib.2 Additionally, 18F‐, 125I‐, and 211At‐labeled PARP‐1 inhibitors derived from a second cancer therapeutic, rucaparib, have recently been radiosynthesized and investigated in preclinical and human studies.3,4 This work aims to investigate radiobromination conditions for the preparation of a 77Br‐labeled rucaparib derivative.
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Methods Bromine‐77 and bromine‐80m were produced at the University of Wisconsin through proton irradiation (40 μA for 1‐2 h at 13.3 MeV) of Co77Se or Co80Se, respectively, and each isolated through dry distillation. The final preparation of 1.4 GBq [77Br]bromide (or 0.6 GBq [80mBr]bromide) was in 500 μL of 20 mM K2SO4 in 1:1::MeCN:H2O. Precursor (1‐(4‐(4,4,5,5‐ tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)phenyl)‐8,9‐dihydro‐ 2,7,9a‐triazabenzo[cd]azulen‐6(7H)‐one; pre‐KX1‐Bpin) and standard (1‐(4‐iodophenyl)‐8,9‐dihydro‐2,7,9a‐ triazabenzo[cd]azulen‐6(7H)‐one; iodo‐KX‐1) were synthesized at the University of Pennsylvania as previously described.4 Copper catalyst (tetrakis (pyridine)copper(II) triflate; Cu (py)4(OTf)2) and ligand (3,4,7,8‐tetramethyl‐ 1,10‐phenanthroline; Lig) were obtained from Sigma Aldrich. Radiochemical reactions shown in Figure 1 were investigated by varying solvent volume and comload, Cu‐Lig molar ratios, position, K2SO4 and temperature. Reactions were monitored by autoradiography‐visualized silica thin layer chromatography (radioTLC) developed with 3:1 EtOAc:MeCN. The reactions were purified by Waters C18 light cartridge, followed by preparative HPLC (Kinetix XB‐C18, 5 μm, 100 Å, 10 × 250 mm, 4 mL/min 40:60 MeCN:0.1 M NH4formate, pH 4.5). Radiochemical conversion was determined by dose calibrator measurement (Capintec CRC 15R, setting #121 for 77Br, setting #170 for 80mBr) of purified fractions. The radiopeaks from five radiolabeling reactions were collected, concentrated by C18 cartridge purification, and re‐run through prepHPLC to determine the final purified mass via 254 nm absorbance. Stable iodo‐KX1 was used as a standard to estimate the
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mass/absorbance calibration curve for 77Br‐radiolabeled compound molar activity. Results Radiochemical conversion yields from 99%. In vitro autoradiography in brain sections of an 18‐month old A53T mouse showed increased binding in regions displaying high α‐syn antibody staining (Figure 1B), which suggests binding of [125I]BJ‐1‐094 to α‐syn in tissue, although further evaluation is still warranted. Conclusions Since [125I]BJ‐1‐094 hits two binding sites on α‐syn fibrils, it is a promising new ligand for an efficient first screening of new lead compounds for α‐syn targeted PET tracer development. ACKNOWLEDGMENTS The Michael J. Fox Foundation is acknowledged for funding.
RE FER EN CES 1. Kotzbauer, P.T., Tu, Z. and Mach, R.H., Clin. Transl. Imaging 2017, 5, 3‐14. 2. Peng, C. et al., Nature 2018, 557, 558‐563. 3. Hsieh, C.‐J. et al., ACS Chem. Neurosci. 2018, 9, 2521‐2527.
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Radiolabeled compounds ‐ neurosciences session 1 O-53 | Synthesis of [18F]fluorotetrazines and coupling to trans‐cyclooctene functionalized antibodies for amyloid‐beta PET Johanna Rokka1; Xiaotian Fang2; Greta Hultqvist1; Rebecca Faresjö1; Dag Olberg3; Gunnar Antoni4; Lars Lannfelt5; Dag Sehlin5; Stina Syvanen5; Jonas Eriksson5 1
Uppsala University, Sweden; 2 Yale University, USA; 3 Norsk medisinsk
syklotronsenter AS/University of Oslo, Norway; 4 Uppsala University Hospital, Sweden; 5 Uppsala University Hospital and Department of Medicinal Chemistry, Uppsala University, Sweden
Objectives Biomolecules such as monoclonal antibodies and engineered derivatives are increasingly used in therapy and diagnostics owing to their high specificity and high‐ affinity binding properties. PET tracers based on large proteins typically have slow equilibrium biodistribution and clearance from blood and consequently labelled with radioisotopes with long half‐lives, e.g., zirconium‐89, copper‐64 or iodine‐124. If these limitations could be overcome, labelling with fluorine‐18 would potentially simplify logistics surrounding the PET examination, reduce radiation dose, modify excretion patterns, and improve PET data by the shorter positron emission range. In an on‐going effort to develop antibody‐based imaging of cerebral amyloid‐beta, structural modifications are investigated towards enhanced kinetics and brain uptake of labelled antibody constructs, e.g., reduction of the molecular weight and introduction of active BBB transport by transferrin receptor (TfR) binders.[1,2] The work on antibody constructs has been paralleled with
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development of a practical method for 18F‐labelling of biomolecules. In this study trans‐cyclooctene (TCO) modified antibodies were labelled by inverse electron‐demand Diels‐Alder reaction with [18F]fluorotetrazines and subjected to biological evaluation. Methods The antibodies were labelled in a three‐step procedure. 1) An anion exchange cartridge containing trapped [18F] fluoride was eluted with a precursor solution, instantly forming [18F]F‐Py‐TFP [3] activated ester. 2) The [18F]F‐ Py‐TFP obtained in the eluate was reacted with tetrazine amine in the presence of base. 3) The formed [18F] fluorotetrazine was purified by semi‐preparative HPLC and conjugated with TCO‐modified antibody. The 18F‐ labelled amyloid‐beta antibody constructs were evaluated in Alzheimer's disease mouse models and wild type controls using micro‐PET. Results The radiochemical yield of [18F]F‐Py‐TFP activated ester was 62 ± 12% and the yield of [18F]fluorotetrazine was 47 ± 18%. Using the inverse Diels‐Alder conjugation >85% of [18F]fluorotetrazine was coupled with TCO‐ modified antibody. Two different fluorine‐18 labelled bispecific antibodies showed approximately 10 and 50‐fold increased brain concentrations at 2 h post injection compared to antibodies without TfR binders. PET imaging was performed at 12 h post injection with the antibody construct based on a full‐sized anti amyloid‐ beta IgG fused with single chain variable fragments of TfR antibody 8D3, [18F]mAb‐scFv8D3. Animals with expression of amyloid‐beta displayed a 2‐fold higher radioactivity brain concentration compared to wild‐type mouse lacking amyloid‐beta. The difference was also visually apparent in the PET images. Scull uptake was minimal and decreased over time indicating very limited defluorination.
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Conclusion Fluorine‐18 labelling has been developed and successfully applied in the benchmarking of antibody‐based PET imaging of cerebral amyloid‐beta with the aim to facilitate clinical applications. R EF E RE N C E S 1. Hultqvist G, Syvänen S, Fang XT, Lannfelt L, Sehlin D. Theranostics 2017; 7(2):308‐318. 2. Fang XT, Hultqvist G, Meier SR, Antoni G, Sehlin D, Syvänen S. Neuroimage. 2019 184:881‐888. 3. Olberg DE, Arukwe D, Grace D, Hjelstuen OK, Solbakken M, Kindberg GM, Cuthbertson A. J. Med. Chem., 2010; 53 (4):1732–1740
Radiolabeled compounds ‐ neurosciences session 1 O-54 | Automated routine implementation of [11C]ITDM for a longitudinal evaluation of mGluR1 availability in the Q175DN mouse model for Huntington's disease Špela Korat1; Daniele Bertoglio1; Klaudia Cybulska1; Jeroen Verhaeghe1; Alan Miranda1; Ladislav Mrzljak2; Jonathan Bard2; Celia Dominguez2; Longbin Liu2; Ignacio Munoz‐Sanjuan2; Sigrid Stroobants3; Leonie Wyffels1; Steven Staelens1 1
Molecular Imaging Center Antwerp, University of Antwerp, Belgium;
2
CHDI Foundation, USA; 3 Antwerp University Hospital, Belgium
Objectives Huntington's disease (HD) is an autosomal dominant neurodegenerative disease characterized by a polyglutamine
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expansion leading to the formation of mutant huntingtin (mHTT) protein1. In order to gain better understanding of mHTT involvement in the cell signaling of glutamatergic receptors, we exploited the use of [11C]ITDM (a selective radioligand for mGluR12) in the Q175DN knock‐in HD mouse model for a longitudinal evaluation over disease progression. Methods Automated radiolabeling of [11C]ITDM (Figure 1A) was carried out by bubbling [11C]CH3I into a freshly prepared and cooled (−20°C) solution of the arylstannane precursor, K2CO3, CuCl, Pd2(dba)3 and P(o‐tol)3 dissolved in anhydrous DMF, until a plateau was reached. After 5 min at 65°C, the mixture was filtered and purified by reverse phase semi‐preparative HPLC (Waters XBridge 5 μm 10 mm × 150 mm; CH3CN:H2O:Et3N (6:4:0.01, V/V/V); 2.7 mL/min). The collected fraction (Rt ∼ 8 min) was trapped on an Oasis HLB cartridge and eluted over a sterile filter with ethanolic saline containing 0.5% ascorbic acid. Ninety‐minutes of dynamic microPET/CT images were acquired after intravenous administration of [11C]ITDM in heterozygous (HET) Q175DN mice (n = 21) and wild‐type (WT) littermates (n = 22) at the age of 6 and 12 months with a third time‐point at 16 months underway. Total volume of distribution (VT) (Logan) was calculated noninvasively using an image‐derived input function for distinct brain regions, including striatum (STR), motor cortex (motor CTX), thalamus (thal), hippocampus (HC), pons, and cerebellum (CB). Results [11C]ITDM was obtained in an acceptable radiochemical yield of 4.9 ± 2.3% (RCY; n = 31, based upon theoretical yield of [11C]CO2), a radiochemical purity (RCP) of >99% and a molar activity (Am) of 82.2 ± 29.1 GBq/μmol
A) Chemical structure of [11C]ITDM. B, C) VT (Logan) values of [11C]ITDM in the motor cortex (B) and in the cerebellum (C) at the age of 6 and 12 months. WT‐ wild‐type, HET‐ heterozygous, *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. Red star defines difference within HET, blue star defines difference between genotypes
FIGURE 1
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(n = 31) at the end of synthesis. Total synthesis time, from the end of bombardment and including formulation, was approximately 31 min. At the age of 6 months significantly higher uptake was detected in HET Q175DN mice in the motor cortex (WT = 3.38 ± 0.52, HET = 3.87 ± 0.72; 14.4 ± 5.7%, p < 0.01, Figure 1B) and in the cerebellum (WT = 7.08 ± 1.38, HET = 8.02 ± 1.78; 13.3 ± 6.9%, p < 0.05, Figure 1C). At the age of 12 months, this significantly higher uptake remained only in the cerebellum (WT = 5.35 ± 0.97, HET = 6.46 ± 0.75; 20.6 ± 5.3%, p < 0.05). Additionally, we observed a significant temporal decrease of [11C] ITDM in all brain regions between both time‐points in both genotypes (in the motor CTX, p < 0.05; in the HC, thal, p < 0.001; in the STR, pons, CB, p < 0.0001) within WT and (in the thal, pons, p < 0.001; in the STR, motor CTX, HC, CB, p < 0.0001) within HET. Conclusions A reliable and highly reproducible automated radiosynthesis of [11C]ITDM was established, with good RCY, Am and RCP achieved throughout the study. ACKNOWLEDGEMENTS This work was funded by CHDI Foundation, Inc, a nonprofit biomedical research organization exclusively dedicated to developing therapeutics that will substantially improve the lives of HD‐affected individuals. R EF E RE N C E S 1. Ribeiro F. M.; Pires R. G. W.; Ferguson S. S. G. Molecular Neurobiology 2011, 43, 1‐11 2. Fujinaga M.; Yamasaki T.; Maeda J.; Yui J.; Xie L.; Nagai Y.; Nengaki N.; Hatori A.; Kumata K.; Kawamura K.; Zhang M. ‐R. Journal of Medicinal Chemistry 2012, 55, 11042‐11051.
Keynote lecture 5 O-55 | Development of radiopharmaceutical; from bench to FDA approved clinical application Hank F. Kung1,2 1
Department of Radiology, University of Pennsylvania, Philadelphia, PA,
USA; 2 Five Eleven Pharma Inc, Philadelphia, PA, USA
In 1981, the passage of the Bayh‐Dole act by the US congress allowed researchers in the US academic institutions to patent and market their inventions by guaranteeing patent rights to the awardee organization. This provided certain encouragement as well as financial incentive for research universities in the US to get involved in translating technologies from bench to market. The intent of the
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law was to make the results of government funded research available for further commercial development, which may benefit the public (consumers); in return, the academic institutions would benefit by owing patents and receiving royalty revenues from the commercialization of the technology. However, the execution of this law is not as simple as it appears. First of all, in order to make their discoveries clinically useful, researchers need to understand the needs of medical practice and its relationship with financial aspect of the health care “industry.” This practical mindset is not always compatible with academic priorities. An on‐going discussion between the clinic and the academic laboratory is imperative for successful translational research. Researchers need to consider cost and convenience as well as distribution and use. An imaging agent may provide beautiful images for publication and yet it may not be practical for diagnosis or too expensive for daily use. For example, in order to develop radioactive probes a radiochemist needs to understand how probes are distributed to nuclear medicine clinics, which isotopes are most useful in the typical clinical setting and whether clinicians (ie the customers) are interested in the additional data that the probe could provide. When a viable agent, with real clinical utility has been created, the researcher may have to spend years bringing the drug to the market. First of all, as non‐profit institutions, universities are not set up to handle the commercialization or development of new technologies or a new drug. The logistics of patent filing and licensing the technology to commercial companies is sometimes very difficult to manage and execute in an academic setting. In order to move a potential drug through the clinical trials required by the FDA approval process, millions of dollars of additional funding are needed. The processes of raising money from venture capitalists, licensing the agent and forming a startup company are not compatible with the traditional academic mission. The conflict of interest, or the appearance of it, causes many “pure and high minded” researchers to pause, contemplate and rethink their job description and the “dignity” of academic life. Examples of translational research in an academic institution by considering the development of two brain imaging agents will be presented by using two case studies: 1. TRODAT‐1, which can be used to diagnose and monitor Parkinson's disease and 2. AV‐45 (Amyvid), an imaging agent for mapping amyloid plaques in the brain in patients at risk of having Alzheimer's disease. Trials and tribulations of developing radiopharmaceuticals from bench to clinics will be presented and discussed. Pros and cons are to be examined from the angle of researchers (academician) as well as investors (Drug Company). Take a deep breath, this is going be a rocky ride.
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Automation/microfluidics/process development O-56 | High‐throughput radio‐TLC using Cerenkov luminescence imaging Jia Wang1; Alejandra Rios1; Ksenia Lisova1; Roger Slavik2; Arion F. Chatziioannou2; R. Michael van Dam2 1
UCLA, USA; 2 Crump Institute for Molecular Imaging, UCLA, USA
Objectives Radio thin layer chromatography (radio‐TLC) is commonly used to analyze purity of radiopharmaceuticals and to determine reaction conversion during radiosynthesis optimization. In many applications, radio‐ TLC is preferred over radio‐high‐performance liquid chromatography (radio‐HPLC) due to its simple procedure and instrumentation, quantitative accuracy and relatively short measurement time. However, with current radio‐TLC methods, it is cumbersome to analyze a large number of samples when using emerging technologies for high‐ throughput reaction optimization or labeling libraries of compounds. In a couple of studies, Cerenkov luminescence imaging (CLI) has been used for reading of radio‐TLC plates spotted with a variety of isotopes, and here we show that this approach can be extended to high‐throughput radio‐TLC analysis of complex mixtures of 18F‐labeled and 177Lu‐labeled radiopharmaceuticals including (S)‐N‐ ((1‐allyl‐2‐pyrrrolidinyl)methyl)‐5‐(3‐[18F]fluoropropyl)‐
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2,3‐dimethoxybenzamide ([18F]fallypride), [18F] 18 177 fluoroethyl‐tyrosine ([ F]FET), and [ Lu]Lu‐PSMA‐617. Methods Crude [18F]fallypride, [18F]FET, and [177Lu]Lu‐PSMA‐ 617 were synthesized by previously reported methods [1]–[3], deposited on TLC plates (unmodified and RP‐18 modified silica gel 60 F254 sheets), and developed with appropriate mobile phases. After drying, the plates were imaged for 5 min with a custom Cerenkov imaging system [4]. Briefly, the radio‐TLC plate was placed in a light‐tight chamber, covered with a transparent substrate, and Cerenkov light was detected by a sensitive CCD camera equipped with a 50 mm lens. Using custom‐written MATLAB software, images were processed and regions of interest (ROIs) were drawn to enclose the radioactive regions/spots. For each sample, the proportion of integrated signal in each ROI was computed. Results The greater separation resolution of CLI was readily apparent for a TLC plate after separation of samples of crude [18F]FET (n = 2) and crude intermediate product (n = 2). In addition to expected species, a low‐abundance side product (6 ± 0% of activity, n = 2) was easily visible in these samples (Figure 1A), but was not discernable using the radio‐TLC scanner (Figures 1B,1C). Leveraging this superior resolution, we observed that all species ([18F]fluoride, [18F]Fallypride, and minor impurity) could be clearly resolved via CLI in crude [18F]Fallypride samples (n = 8) with only 15 mm separation distance
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(Figure 1D), unlike the chromatogram from the radio‐ TLC scanner, in which severe peak overlap was observed (Figure 1E). The short separation distance enables each set of samples to be rapidly developed, and allows several sets of samples to be imaged simultaneously (e.g., 2 plates of 8 samples). To explore the application of CLI‐based radio‐TLC analysis to additional isotopes, labeling yield of [177Lu]Lu‐PSMA‐617 was measured as a function of reaction time. We observed that high labeling efficiency (99%) can be achieved in just 10 min, rather than the typical 30 min timeframe used (Figure 1F). Conclusions Spotting multiple sample per TLC plate combined with readout via CLI is a practical method for rapid, high‐ throughput radio‐TLC analysis. It provided significantly higher resolution, the ability to image multiple samples in parallel in shorter time, and the ability to quantify low‐ abundance impurities that were not discernable with radio‐TLC scanning. CLI of TLC plates has a broad application for the analysis of radiotracers labeled with radionuclides that are positron emitters used for PET imaging and radiopharmaceuticals labeled with beta emitters. ACKNOWLEDGMENTS The authors are grateful for support from the NCI, NIMH, and NIBIB. R EF E RE N C E S 1. Wang et al., Lab. Chip 17: 4342–4355, 2017. 2. Hamacher and Coenen, Appl. Radiat. Isot. 57: 853–856, 2002. 3. Fendler et al., J. Nucl. Med. 58: 1786–1792, 2017. 4. Dooraghi et al., Analyst 138: 5654–5664, 2013.
Automation/microfluidics/process development O-57 | Rapid, inexpensive, and high‐yielding radiosynthesis of 68Ga‐PSMA using a versatile microfluidic device for prostate cancer PET imaging Xin Zhang; Michael Nickels; Fei Liu; Leon Bellan; Henry Manning Vanderbilt University, USA
Objectives Prostate cancer has become the second most common cancer in men worldwide. Prostate specific membrane antigen (PSMA) represents a highly sensitive and specific molecular target for imaging and therapy because of its overexpression on prostate cancer cells. Herein, we report the development of an inexpensive and high‐yielding
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microfluidic chip‐based radiosynthesis of both 68Ga‐ and Lu‐PSMA. Preliminary results suggest a promising technology that can be easily adaptable to the clinical environment allowing for PET imaging and therapy at substantially reduced costs. Methods The microfluidic chip was constructed with three key components: an on‐chip strong cation exchange (SCX) column, followed by an on‐chip strong anion exchange (SAX) column, and a passive in‐plane mixing/reaction module.1 The entire chip is first placed on a hot plate that is preheated to 95°C. Starting with generator (iTG) produced [68Ga]GaCl3 in HCl, the isotope was first isolated using the on‐chip SCX column, followed by elution with a solution of NaCl in HCl. The isotope, now in the form of [68Ga]GaCl4−, was isolated using the on‐chip SAX column and finally eluted using 200 mL of pure water.2 Upon elution of the isotope, the solution was mixed by flowing through the on‐chip micromixer with 200 ml of PSMA‐11 precursor dissolved in a sodium acetate solution. Radiochemical yield (RCY) and radiochemical purity were determined by both Radio‐TLC and Radio‐HPLC. Results Rigorous testing of the SCX and SAX columns revealed that 8 mg of the SCX and 10 mg of the SAX resins were needed to obtain efficient trapping. A full elution of the gallium‐68 generator (4 mL) was concentrated using the on‐chip SCX column with greater than 98% (n = 6) efficiency over 5 minutes. Elution off of the SCX and onto the SAX was achieved using as low as 700 mL of a NaCl (5 M)/ HCl (5.5 M) solution, which was followed by elution of the gallium‐68 using pure water (200 mL) with greater than 92% (n = 6) efficiency. Flow through the mixing of gallium‐68 solution and the PSMA precursor solution was achieved within 1 minute by leveraging a novel in‐ plane passive micromixer, designed with diamond‐shaped obstructions placed inside the microchannel with geometric variations throughout. Analysis of the reaction product revealed the overall process resulted in 100% radiolabeling efficiency (n = 12) and little to no difference in radiochemical or chemical impurities when directly compared to clinically produced 68Ga‐PSMA‐11. Of particular note is the fact that no additional purification of the reaction product was needed to observe the high purity levels. Conclusions This work demonstrated the ultrafast and high‐yielding radiosynthesis of 68Ga‐PSMA using an inexpensive and versatile microfluidic chip. This new design of a microfluidic chip has demonstrated many desirable attributes that hold promise to advance on‐demand personalized radiopharmaceutical production. Imaging experiments along with the Lu‐177 experiments are ongoing. 177
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Automation/microfluidics/process development O-58 | Automated radiosynthesis of [18F] atorvastatin via Ru‐mediated 18F‐ deoxyfluorination: A prospective PET imaging tool for the assessment of statin related mechanisms of action Goncalo Clemente1; Jens Rickmeier2; Tryfon Zarganes‐Tzitzikas3; Ines Antunes4; Riemer Slart3; Alexander Dömling3; Tobias Ritter2; Philip Elsinga1 1
University Medical Center Groningen, Netherlands; 2 Max‐Planck‐Institut
für Kohlenforschung, Germany; 3 Department of Drug Design, University of Groningen, Netherlands; 4 UMCG, Netherlands
Introduction Cardiovascular diseases represent the leading cause of death globally, having high incidence rates regardless of each country income level.1 Since the 1970s, when the first statin was isolated and screened as a potent 3‐hydroxy‐3‐methyl‐glutaryl‐coenzyme A reductase (HMGCR) inhibitor, this class of lipid‐lowering agents became the spine of primary and secondary cardiovascular disease prevention. HMGCR is an enzyme involved in the production of endogenous cholesterol and the structure‐based rational quest for more powerful inhibitors ended up with numerous statins being synthesized and added to medical prescription. In addition to their unambiguous cholesterol‐lowering effects, the success of statins is increasingly being connected with its pleiotropic effects.2 More and more often statins are being associated with potential protective effects on other pathologies (e.g., respiratory, carcinogenic, viral, neurodegenerative). Although these data are strongly suggestive, the exact off‐target effects of statins have not been proven in vivo. On the other hand, some patients revealed to be statin‐resistant or statin‐intolerant.3 Therefore, an increasingly specific knowledge of the subcellular mechanisms affected by statins and the development of a more sensitive toolbox to investigate this subject is currently challenging in medicinal chemistry. Objective Herein, we propose the radiofluorination of atorvastatin, the most widely used statin in the prevention of cardiovascular risk factors and one of the bestselling drugs in pharmaceutical history. By taking advantage of the fluorobenzene ring present in atorvastatin, we intend to produce the radiolabeled analogue [18F]atorvastatin without changing the physicochemical characteristics of the original molecule. We believe that this positron emission
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tomography (PET) tracer may have the potential to unveil some of the statin‐related mechanisms of action by supporting the development of highly sensitive in vitro quantitative techniques to compare cellular and subcellular localization. Off‐target activity and pharmacokinetics can potentially be identified by mapping the radiotracer biodistribution over time. To evaluate these hypotheses, in vitro and in vivo experiments are currently ongoing. Methods First, a phenol‐derived [18F]atorvastatin precursor with a ketal and tert‐butyl ester protected side‐chain was synthesized and then the phenol substituent was complexed to a ruthenium fragment to decrease electron density and activate the arene for subsequent nucleophilic aromatic substitution.4 This strategy unlocks the access to 18F‐fluorination of aromatic rings lacking electron withdrawing groups. 18F‐Deoxyfluorination and deprotection were manually optimized and then translated to automation, taking into account the particularities and constraints (i.e. limitation of volumes, fluid trajectories, arrangements) of the selected synthesis module (Synthra RNplus), to obtain [18F]atorvastatin reformulated into an injectable physiological saline solution. Results To date, the full synthesis, purification and reformulation of [18F]atorvastatin has been consistently achieved, reinforcing the robustness of this 18F‐deoxyfluorination method. After a total time of approximately 75 min., stable (at least up to 3 h when incubated in solution or human serum) [18F]atorvastatin with radiochemical purity ≥95% was obtained in moderate isolated yields of 20.4% ± 1.9% (d.c.) during the manual optimization tests, being already adequate for the planning and performance of pre‐clinical assays (molar activity 112 ± 77 GBq/μmol). Despite the reduced radiochemical yields obtained to date with the chosen automated module (approx. 5%), the acquired data forecast an interesting margin of progression for the enhancement of the final characteristics and efficiency of the process. Conclusions Here we demonstrate the suitability of the late‐stage 18 F‐deoxyfluorination strategy to be automated in order to achieve the radiolabeling of phenol derived Ru‐ coordinated complexes to routinely produce [18F]atorvastatin. In vitro and in vivo studies are currently ongoing to evaluate the potential of this radiolabeled statin to identify off‐target activity. Ultimately, [18F]atorvastatin might be used to distinguish between statin‐resistant and non‐resistant patients for personalized therapy, thereby the first in human PET studies are already being envisaged at our department.
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R EF E RE N C E S 1. Roth GA et al. [2017], J Am Coll Cardiol, 70(1):1 2. Oesterle A et al. [2017], Circ Res, 120(1):229 3. Reiner Ž [2014] Nutr Metab Cardiovasc Dis, 24(10):1057 4. Beyzavi MH et al. [2017] ACS Cent Sci, 3(9):944.
Automation/microfluidics/process development O-59 | Online positron detector for LC/MS/MS Anna Kirjavainen1; Salla Lahdenpohja1; Sarita Forsback2; Olof Solin2 1
Turku PET Center, University of Turku, Finland; 2 University of Turku,
Finland
Objectives LC/MS/MS is wildly used in chemical research and increasingly also in radiochemical and radiopharmaceutical research. Obviously, combination of online radiodetection and LC/MS/MS is highly desirable. Design parameters for our research for a simple and robust radiodetector for LC/MS/MS were high sensitivity for β+‐radiation, low sensitivity for γ‐radiation and low noise characteristics. Methods Radio‐LC/MS/MS was performed with a linear ion trap quadrupole mass spectrometer (QTRAP, Applied Biosystems SCIEX, Canada) equipped with a turbo ion spray source, an Agilent 1100 series pump (Agilent Technologies, USA), a 0.5 μl Rheodyne injector (Rheodyne, USA) and various chromatographic columns compatible with LC/MS/MS. The radioactivity detector was placed between the column outlet and MS inlet. The radioactivity detector consisted of a thin‐walled teflon tube and a plastic scintillator (Meltilex®, Perkin Elmer, Finland), with an active volume of ~0.1 μl embedded in the scintillator fused on the surface of a photomultiplier tube (PMT). Scintillation light from β+‐particles interacting with the scintillator was detected by the double‐cathode PMT (R1548,
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Hamamatsu, Japan)1 and this scintillation signal was converted to a millivolt signal proportional to the radioactivity concentration eluting from the chromatographic column. Results Figure 1 shows a representative presentation of the system performance. A sample from radiosynthesis is injected on to the system and relevant single ion masses are followed, in this case m/z 301 amu and m/z 317 amu2. It can be seen that certain mass signals correspond to a particular radioactivity signal. Note, that no separate shielding is installed between the LC column and MS inlet, demonstrating the high sensitivity and low background level of the system. Conclusions The prototype detector3, which has now been used for several years in our laboratory, has proven to be robust, sensitive, and highly useful. RE FER EN CES 1. Nickles et al. IEEE transactions on nuclear science, 1992, 39:2316 2. Kirjavainen et al. Mol Imaging Biol. 2013,15:131 3. Lahdenpohja et al. Manuscript in preparation 2018
FIGURE 1 Radiochromatogram from the radiodetector between the outlet of a HPLC column and inlet of the MS and two selected single ion mass traces from the MS. The insert depicts the light‐ shielded radio‐detector head with PM tube, scintillator and teflon tube embedded in the scintillator
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Radiolabeled compounds ‐ neurosciences session 2 O-60 | Radiosynthetic optimization of the SV2A radiotracer best precursor
18
F‐SDM‐8: A search for the
Xiaoai Wu1; Songye Li2; Ming‐Qiang Zheng3; Yiyun Huang4 1
Sichuan University, China; 2 Yale PET Center, Department of Radiology
and Biomedical Imaging, Yale University School of Medicine, USA; 3 Yale University School of Medicine, USA; 4 PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA
Objectives Dysfunction/disruption of synapses is associated with a variety of diseases such as Alzheimer's disease, epilepsy, depression and schizophrenia. The synaptic vesicle glycoprotein 2A (SV2A), one of the major membrane proteins on the synaptic vesicles, is crucial to neurotransmission, and can be used as a biomarker for synaptic density/integrity measurement in neurodegenerative and psychiatric diseases. We have previously developed and validated 11C‐UCB‐J as a radiotracer for the imaging and quantification of SV2A.1,2 However, with 20‐min half‐life of the 11C‐radionuclide, 11C‐UCB‐J has to be produced and used on‐site, and hence is not suitable for distribution and applications in multi‐center clinical trials or diagnosis of diseases in the clinics. Therefore, we set out to develop 18F‐labeled SV2A radiotracers. A structure‐activity relationship study led to the discovery of 18F‐SDM‐8, which has been shown to have higher specific binding in vivo than 11C‐UCB‐J in nonhuman primates.3 Thus 18F‐SDM‐8 holds great promise to be an excellent radiotracer for SV2A imaging. The aim of this study was to screen 18F‐radiolabeling precursors and find the best one for the routine production of 18F‐ SDM‐8. Methods Eight precursors, including those newly developed in recent years,4–6 were prepared from commercially available materials. Efficiency of F‐substitution was tested with each precursor using 10 eq. of KF to the precursor under simulated radiolabeling conditions. Test radiolabeling was then performed with each precursor under different conditions by varying the 18F‐fluoride elution methods, reaction solvents (DMF, DMSO and DMA), temperatures (110‐150°C), and times (10‐30 min). The radiochemical yield (RCY) was calculated based on integration of the product peak on the HPLC chromatogram, or as the ratio between the activity of collected product
fractions and the total activity injected onto the HPLC column. Results All precursors (Figure 1) were successfully synthesized with overall yield ranging from 20% for the boronic acid precursor (3, Figure 1) to 37% for the quaternary ammonium salt (2). Test runs with KF under simulated radiolabeling conditions (heating at 140°C for 20 min in DMA with the reagents listed in the table) indicated that the highest 19F‐incorporation yield was achieved with the trimethyltin precursor (7), followed by boronic acid (3), tributyltin (8), the Ritter precursor (1), boronic ester (4), iodonium ylide (6), iodonium salt (5), and quaternary ammonium salt (2). In radiolabeling tests, except for the Ritter precursor, reactions in DMA gave slightly higher RCY than those in DMF or DMSO. Extension of reaction time, however, did not lead to higher RCY. The highest RCY was obtained in the copper (II)‐catalyzed reaction with the trimethyltin precursor (7) in DMA at 110°C (24%) and with the Ritter precursor (1) in DMSO at 140°C (30%). Radiolabeling of the boronic ester precursor (4) in DMA resulted in moderate RCY (6% at 110°C and 11% at 140°C), while ~2% RCY was achieved with the iodonium ylide precursor (6) in DMF at 110 or 140°C. We also found that the radiotracer racemized when heating above 120°C with high concentration of bases (> 4 mg/mL). Hence, subsequent radiolabeling runs were all conducted at 110°C and the results listed in the table. Overall, optimal RCY (24%, decay‐uncorrected) was achieved with the trimethyltin precursor (7) heating in DMA at 110°C for 20 min. These conditions were then used in validation runs to produce 18F‐SDM‐8 for IND submission and for use in human studies. The total synthesis time was ~90 min from the end of bombardment. Mean molar activity of 18F‐SDM‐8 was 241.7 MBq/nmol at the end of synthesis (n = 4). Conclusions Eight precursors for 18F‐SDM‐8 were successfully synthesized and tested. Overall the trimethyltin precursor can be prepared in high yield and radiolabeling of this precursor provided the highest radiochemical yield for 18 F‐SDM‐8 with good molar activity. 18F‐SDM‐8 has since been advanced to PET imaigng evaluation in human subjects. RE FER EN CES : 1. Nabulsi N et al. J Nucl Med 2016; 57:777. 2. Finnema SJ et al. Sci Transl Med 2016; 8:348. 3. Li S et al. J Nucl Med 2018; 59:S68. 4. Preshlock S et al. Chem Rev 2016; 116:719. 5. Neumann CN et al. Nature 2016; 534:369. 6. Makaravage KJ et al. Org Lett 2016; 18:5440.
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Radiolabeled compounds ‐ neurosciences session 2 O-61 | Discovery and first‐in‐human evaluation of M4 PAM PET tracer [11C]MK‐6884 Wenping Li1; Yuchuan Wang; Zhizhen Zeng1; Talakad Lohith1; Ling Tong1; Robert Mazzola1; Kerry Riffel2; Patricia Miller1; Mona Purcell1; Marie Holahan1; Hyking Haley1; Liza Gantert1; John Morrow1; Tjerk Bueters1; Jason Uslaner1; Jan de Hoon3; Guy Bormans4; Michel Koole4; Koen Laere4; Kim Serdons4; Ruben Declercq5; Inge Lepeleire5; Michael Rudd1; David Tellers1; Anthony Basile1; Eric Hostetler1 1
Merck Research Laboratories, USA; 2 Merck & Co, Inc, USA; 3 University
Hospital Leuven, Belgium; 4 KU Leuven, Belgium; 5 Merck Sharp & Dohme (Europe) Inc, Belgium
Objectives Modulating the cholinergic system by specifically targeting the M4 muscarinic acetylcholine receptor (mAChR) is a novel approach for the treatment of behavioral symptoms
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in patients with Alzheimer's disease and schizophrenia. Development of a selective M4 positive allosteric modulator (PAM) has been proposed as a strategy to overcome the challenges of developing a selective orthosteric M4 agonist. Moreover, measurements of receptor occupancy (RO) using PET is a key biomarker for assessing target engagement at a PAM site on the M4 receptor, as well as an aid in defining therapeutically‐relevant doses. These benefits of PET imaging have led to the discovery of the M4 PAM PET tracer [11C]MK‐6884 (Figure 1) and its clinical validation in healthy human subjects. Methods [11C]MK‐6884 was synthesized by N‐alkylation of the parent lactam with [11C]methyl iodide resulting in good radiochemical yield with high radiochemical purity and molar activity. In vitro autoradiographic and tissue homogenate binding studies were carried out with [3H]MK‐6884 to determine the regional distribution of tracer binding, the Kd values, and target concentration (Bmax) in rhesus monkey and human brain tissues. In vivo imaging studies were performed in Rhesus monkeys under baseline and blocking conditions with [11C]MK‐6884. Clinical PET
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SUPPLEMENT ARTICLES 1
Yale PET Center, Department of Radiology and Biomedical Imaging,
Yale University School of Medicine, USA; 2 PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA; 3 Department of Nuclear Medicine, West China Hospital, Sichuan University, China; 4 Yale PET Center, USA; 5 Department of Psychiatry, Yale University, USA
FIGURE 1
Structure of MK‐6884
scans were performed to determine human dosimetry and baseline test/retest variability. Results The binding site distribution of [3H]MK‐6884 in brain slices of rhesus monkey and human showed high binding density localized primarily in the striatum. Moderate binding was observed in the cortex and hippocampus. No displaceable binding was seen in the cerebellum and brainstem. Tissue homogenate binding studies showed MK‐6884 binds at the M4 allosteric site with high affinity (Kd 0.9 nM rhesus monkey striatum, Kd 1.2 nM human striatum) and the Bmax/Kd ratio was similar in both rhesus monkey and human. Baseline PET studies in rhesus monkeys showed good brain uptake in the striatum and low uptake in other brain regions, consistent with the in vitro autoradiography results. Blocking studies with a different M4 PAM reduced tracer binding in the striatum to levels similar to cerebellum. Clinical PET studies with [11C]MK‐6884 demonstrated acceptable dosimetry, good brain uptake that is highest in the striatum, and good baseline test/retest variability. Conclusions [11C]MK‐6884 shows excellent potential for imaging the M4 receptors in vivo: regional distribution consistent with known M4 receptor distribution, a large dynamic range, specificity with regard to tracer binding in the brain, and low baseline test/retest variability. For these reasons, [11C]MK‐6884 is being used to determine central RO of therapeutic M4 PAM compounds in preclinical and clinical studies.
Radiolabeled compounds ‐ neurosciences session 2 O-62 | An 18F‐labeled radiotracer for PET imaging of 11β‐HSD1: From chemistry development to clinical study Songye Li1; Shivani Bhatt1; David Matuskey2; Daniel Holden1; Wenjie Zhang3; Zhengxin Cai2; Nabeel Nabulsi4; Yunpeng Ye1; Hong Gao2; Michael Kapinos2; Richard Carson1; Sherry McKee5; Kelly Cosgrove5; Ansel Hillmer1; Yiyun Huang2
Objectives 11β‐hydroxysteroid dehydrogenase‐1 (11β‐HSD1) converts cortisone to cortisol, a major “stress hormone”. As such, 11β‐HSD1 is believed to be involved in the pathophysiology of stress‐related brain disorders, metabolic diseases, and neurodegenerative diseases. We have previously developed 11C‐AS2471907 as a PET radiotracer to image 11β‐HSD11,2. The presence of three aryl fluorines in the molecule of AS2471907 renders it amenable to 18 F‐labeling via newly developed radiofluorination methodologies. Therefore, we prepared 18F‐AS2471907 as the first 18F‐labeled 11β‐HSD1 PET radiotracer for evaluation in nonhuman primates and translation into studies in humans. Methods Both ortho‐ and para‐18F‐AS2471907 were synthesized using novel iodonium ylide precursors (Figure 1). PET experiments in nonhuman primates were conducted on a Focus‐220 scanner and included baseline and blocking scans with 11β‐HSD1 inhibitors. In the clinical study, four participants each underwent test and retest PET scans on two separate days, while four additional subjects had a single scan, on a High Resolution Research Tomograph (HRRT). Arterial blood samples were drawn for metabolite analysis and construction of arterial input function (AIF). Time‐activity curves (TACs) were generated and fitted with 1‐ and 2‐tissue (1T, 2T) models and the multi‐linear analysis (MA1) method to derive regional distribution volume (VT) using the AIF. In nonhuman primates, target occupancy and non‐displaceable distribution volume (VND) were determined from the blocking scan to assess the specific binding level, represented by non‐ displaceable binding potential (BPND). In the human brain, absolute test‐retest variability (aTRV) in VT was assessed. Results Two iodonium ylide precursors (otho and para to the alkoxy moiety) were synthesized in 7 steps with an overall yield of ~2%. 18F‐AS2471907 was prepared (Figure 1) in high radiochemical purity and molar activity, with the ortho‐precursor giving much higher radiochemical yield than the para‐precursor (34% vs.12%). In rhesus monkeys, metabolism of 18F‐ AS2471907 was slow with ~94% of parent fraction remaining at 30 min post‐injection. Brain uptake was
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1T‐derived VT (mL/cm3) from baseline scans and a blocking scan with ASP3662, and regional BPND in rhesus monkey
TABLE 1
VT
ROI
Baseline (mean ± SD, n = 4)
Blocking (n = 1)
BPND Baseline (mean ± SD, n = 4)
Caudate
4.9 ± 0.9
3.4
0.5 ± 0.3
Cerebellum
8.3 ± 1.3
3.6
1.6 ± 0.4
Frontal cortex
5.7 ± 0.9
3.1
0.8 ± 0.3
Insula
7.0 ± 1.0
3.3
1.2 ± 0.3
12.7 ± 2.1
3.5
3.0 ± 0.7
7.9 ± 1.7
3.9
1.5 ± 0.5
10.0 ± 1.7
3.3
2.2 ± 0.6
4.5 ± 0.9
3.6
0.4 ± 0.3
Occipital cortex Putamen Temporal cortex Thalamus
TABLE 2 2T and MA1‐derived VT (mL/cm3) from baseline scans in human and MA1 VT test‐retest variability.
ROI
2T
MA1
VT (mean ± SD, n = 12)
VT (mean ± SD, n = 12)
TRV aTRV (%) (%)
Caudate
3.2 ± 1.0
3.2 ± 1.0
‐7.0 13.4
Putamen
8.1 ± 3.2
8.0 ± 2.9
4.2 12.7
Frontal cortex
8.5 ± 2.2
8.9 ± 2.5
0.6 14.0
Insula
5.8 ± 1.6
5.7 ± 1.6
2.3 10.0
Occipital cortex
15.9 ± 4.2
15.7 ± 4.2
0.6 16.6
Temporal cortex
9.1 ± 3.5
8.7 ± 2.5
4.3 15.6
Thalamus
13.4 ± 5.6
13.1 ± 5.7
‐2.9 23.4
Cerebellum
12.6 ± 5.5
12.5 ± 5.4
‐10.7 23.9
high with a peak SUV of 5.2, and tissue kinetics was fast. TACs were well‐fitted with the 1T model to provide VT estimates ranging from 4.5 to 12.7 mL/cm3 (Table 1). Pretreatment with the 11β‐HSD1 inhibitor ASP3662 (0.3 mg/kg)3 reduced uptake in all brain regions and produced 94% occupancy, with VND calculated as 3.18 mL/cm3. Regional BPND values were calculated using VND (Table 1) and gave high regional BPND values of 0.4‐2.2 for 18F‐AS2471907 in the monkey brain. In humans, 18F‐AS2471907 also metabolized slowly (87% of parent at 30 min). Brain uptake was good with appropriate kinetics and highest peak SUV of 3.0 in occipital cortex at ~30 min post‐injection. TACs were well described by the 2T model and MA1 method. Mean VT (Table 2) was 7.9 mL/cm3 (range: 3.2‐15.8 mL/ cm3). aTRV for MA1 VT was modest, 99%). The decay‐corrected radiochemical yield was 10.6 ± 3.8% (n = 16). High CB2‐specificity was confirmed by autoradiograms of [18F]CB2‐R1 on CB2‐postive rat spleen and CB2‐deficient rat brain tissues. Biodistribution studies in Wistar rats revealed a specificity of 86% for the CB2‐rich spleen using the commercially available CB2 ligand GW405833 as a blocker. High specific and reversible binding was also confirmed in PET experiments using Wistar rats as demonstrated by displacement experiments. By in vitro autoradiography studies on post‐ mortem human tissues, higher CB2 expression was found in human ALS spinal cord sections compared to control samples. No radiometabolites were detected in the brain up to 45 min after injection. Considerable in vivo defluorination and radioactivity uptake in the Wistar rat skull was observed in the PET experiments. However, defluorination could be circumvented by the replacement of all the hydrogen atoms in the fluoroalkyl side chain by deuterium atoms to afford [18F]CB2‐R1‐d6 (Figure 1). The resulting radioligand, [18F]CB2‐R1‐d6, exhibited a remarkably high stability as confirmed by metabolic identity studies and the lack of radioactivity uptake in the skull by PET imaging in Wistar rats. Conclusion [18F]CB2‐R1‐d6 is a promising radiofluorinated probe that exhibits specificity and selectivity for CB2. The herein presented preclinical data strongly support the clinical translation of [18F]CB2‐R1‐d6. Figure 1: A. Radiosynthetic approach to obtain [18F]CB2‐R1‐d6. B. Autoradiograms of the CB2‐rich rat spleen under baseline and blockade conditions. High CB2‐specificity of [18F]CB2‐R1 was demonstrated by blockade with commercially available CB2‐ ligand GW‐405,833 (10 μM).
Radiolabeled compounds ‐ neurosciences session 2 O-64 | Synthesis and evaluation of
18
F‐labeled benzimidazopyridine derivatives as novel PET tracers for tau imaging
Hiroyuki Watanabe1; Sho Kaide1; Yuta Tarumizu1; Yoichi Shimizu2; Shimpei Iikuni3; Masahiro Ono3 1
Graduate School of Pharmaceutical Sciences, Kyoto University, Japan;
2
Graduate School of Medicine, Kyoto University, Kyoto, Japan; 3 Kyoto
University, Japan
Objectives Neurofibrillary tangles composed of abnormal aggregation of hyperphosphorylated tau proteins are well known as
one of the neuropathological hallmarks of Alzheimer's disease (AD). Since the accumulation of tau aggregates is correlated with impaired cognition and neuronal injury, in vivo imaging of the tau aggregates may be useful for diagnosis and monitoring of the progression of AD. Therefore, several PET tracers for tau imaging have been tested clinically and demonstrated their feasibility1. Recently, we have reported radioiodinated benzimidazopyridine (BIP) derivatives including [123I] BIP‐NMe2 as novel tau tracers for SPECT (Figure 1)2,3. These derivatives showed high and selective binding affinity for tau aggregates in AD brain sectionsand favorable pharmacokinetics in mouse brains. These results encouraged us to develop novel PET tracers based on the BIP scaffold. In this study, we newly designed and synthesized 18F‐labeled BIP derivatives (Figure 1) and evaluated their utility as novel PET tracers for imaging tau aggregates in AD brains. Methods We synthesized five BIP derivatives. 18F‐labeled BIP derivatives were prepared from their corresponding tosylate precursors. In vitro autoradiographic studies were performed using postmortem AD brain sections (frontal lobe (tau (−), β‐amyloid (Aβ) (+)) and temporal lobe (tau (+), Aβ (+))) to evaluate specific binding of these derivatives to tau aggregates. Brain uptake and clearance were measured in normal mice after injection of the BIP derivatives. In addition, we tested in vivo stability in normal mice. Results 18 F‐labeled BIP derivatives were successfully obtained in radiochemical yields of 37‐65% with radiochemical purities of >99%. In in vitro autoradiographic studies, radioactivity of all 18F‐labeled BIP derivatives was accumulated in the temporal lobe (tau (+), Aβ (+)). These labeling patterns corresponded to immunohistochemical staining of anti‐phosphorylated tau antibody. Conversely, no marked accumulation was observed in the frontal lobe (tau (−), Aβ (+)). These results suggested that 18F‐ labeled BIP derivatives bound to tau aggregates selectively in AD brain sections. In addition, the substituted group introduced into 7‐position of BIP scaffold did not affect the selective binding to tau aggregates against Abplaques in in vitro. In biodistribution studies using normal mice, all 18F‐labeled BIP derivatives showed high brainuptake at 2 min postinjection (5.2‐6.8% ID/g) and clearance at 60 min postinjection (1.8‐2.2% ID/g). In addition, these compounds were stable in in vivo in normal mice. Conclusions The findings in the present study suggest that novel 18F‐ labeled BIP derivatives may be useful PET tracers for imaging tau aggregates in AD brains.
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R EF E RE N C E S 1. Villemagne VL, et al. (2018) Nat Rev Neurol, 14, 225‐326. 2. Ono M, et al. (2016) Sci Rep, 34197. 3. Kaide S, et al. (2018) ACS Med Chem Lett, 9, 478‐483.
Radiolabeled compounds ‐ neurosciences session 2 O-65 | Development of a carbon‐11 PET pro‐ radiotracer for imaging the astroglial excitatory amino acid transporter 2 Igor Fontana2; Eduardo Zimmer1; Diogo Souza1; Salvatore Bongarzone2; Antony Gee2 1
Universidade Federal do Rio Grande do Sul, Brazil; 2 King's College
London, United Kingdom
Objectives The excitatory amino acid transporter 2 (EAAT2), mostly located in astrocytes, plays a key role in the clearance and recycling of glutamate, which is the major excitatory neurotransmitter in the mammalian brain. Astroglial EAAT2 dysfunction and glutamate excitotoxicity are implicated in neurodegenerative diseases, such as Alzheimer's disease, amyotrophic lateral sclerosis, epilepsy, Huntington's disease, myotonic dystrophy and schizophrenia1. In this way, small molecules with affinity to EAAT2 are of high interest for understanding the role of glutamatergic excitotoxicity in brain disorders. Greenfield et al.2 synthesised a specific inhibitor of EAAT2 (Fig 1A ‐ IC50 in vitro = 0.7 μM), with suitable molecular structure for carbon‐11 radiolabelling but with a predictive low brain penetrance (typical of carboxylic acids). To overcome this limitation the development of an analogous ester as a pro‐radiotracer to be hydrolysed to the active form within the brain seems a promising strategy. The potential of this approach is supported by successful reports of 18F‐ fluoromethylated pro‐radiotracer which is hydrolysed in
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a similar manner to produce an active EAAT2 radiotracer. The aim of this work is to develop the carbon‐11 labelled pro‐radiotracer ([11C]IF1) which we hypothesise will be hydrolysed to the EAAT2‐targeting radiotracer ([11C]IF2) after passage across the BBB. Methods The [11C]IF1 radiosynthesis procedure was implemented using an Eckert & Ziegler Modular‐Lab system. [11C] CO2 was converted to [11C]CO using a silane lithium derivative as previously reported by Taddei et al.3. The [11C]CO afforded [11C]IF0 via a palladium‐mediated [11C]carbonylation reaction according to Fig 1B. [11C] IF1 was obtained after removal of the BOC protecting group with trifluoroacetic acid at 90 °C for 4 min. The reaction was quenched with PBS/NaOH and the crude product analysed by radio‐HPLC. Results Crude [11C]IF1 was obtained within 18 min after the end of bombardment with radiochemical yield of 8% (decay corrected) based on radio‐HPLC, with a radiochemical purity of 39%. [11C]IF1 was identified following co‐ injection with the non‐radioactive reference compound. Conclusion [11C]IF1, a potential EAAT2 pro‐radiotracer, was successfully synthesised from [11C]CO. Work is in progress to further optimize this reaction and to develop a suitable purification regimen aimed at evaluating the potential of this pro‐radiotracer for in vivo imaging of EAAT2 density in astrocytes. RE FER EN CES 1. Lin CL, Kong Q, Cuny GD, Glicksman MA. Glutamate transporter EAAT2: a new target for the treatment of neurodegenerative diseases. Future Med Chem. 2012;4:1689‐700. 2. Greenfield A, Grosanu C, Dunlop J, McIlvain B, Carrick T, Jow B, et al. Synthesis and biological activities of aryl‐ether‐, biaryl‐, and fluorene‐aspartic acid and diaminopropionic acid analogs as potent inhibitors of the high‐affinity glutamate transporter EAAT‐2. Bioorg Med Chem Lett. 2005;15:4985‐8.
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3. Taddei C, Bongarzone S, Haji Dheere AK, Gee AD. [11C]CO2 to [11C]CO conversion mediated by [11C]silanes: a novel route for [11C]carbonylation reactions. Chem Commun (Camb). 2015;51: 11795‐7.
Radiolabeled compounds ‐ oncology (imaging) session 3 O-66 | Comparison of Al18F and 68Ga‐labeled NOTA‐PEG4‐LLP2A for PET imaging of very late antigen‐4 in melanoma Yongkang Gai; Lujie Yuan; Huiling Li; Xiaoli Lan Department of Nuclear Medicine, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, China
Objectives Melanoma is a highly malignant tumor with an increasing incidence especially among Caucasians and has become one of the major health problems in Western countries. Very late antigen‐4, overexpressed in many tumors including melanoma, lymphoma, and multiple myeloma, is an extremely attractive target for cancer imaging and therapy. In this study, based on a reported promising VLA‐4 targeting ligand LLP2A, two Al18F and 68Ga radiolabeled NOTA‐PEG4‐LLP2A were developed and evaluated for imaging of melanoma. Methods NOTA‐PEG4‐LLP2A was radiolabeled with Al18F and 68 Ga, and purified using C18 cartridge. The radiochemical yield, radiochemical purity and in vitro stability were evaluated. Cell uptake and blocking studies in B16F10 cells were performed and the results were compared. In vivo biodistribution and PET imaging evaluation were performed using B16F10 tumor bearing mice.
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Results The radiochemical yield of [68Ga]Ga‐NOTA‐PEG4‐LLP2A was greater than 95%, while that of [18F]AlF‐NOTA‐ PEG4‐LLP2A was only 40%. Both tracers remain intact after a 4 hrs or 2 hrs incubation in human serum. Both tracers could be internalized rapidly by B16F10 cells. However, a significantly higher uptake was observed in [68Ga]Ga‐NOTA‐PEG4‐LLP2A group. In the PET images, all tumors were clearly visible after injection of two tracers, while [68Ga]Ga‐NOTA‐PEG4‐LLP2A have a better pharmacokinetic profile with lower background in liver. The biodistribution data were consistent with the PET images. Comparable tumor uptakes were observed for Al18F and 68Ga radiolabeled tracers (8.9 ± 2.3%ID/g vs 7.9 ± 1.6 %ID/g at 1 h, 7.3 ± 1.5 %ID/g vs 7.8 ± 0.7 %ID/g at 2 h). However, the tumor/background ratios of [68Ga]Ga‐NOTA‐PEG4‐LLP2A were superior to those of [18F]AlF‐NOTA‐PEG4‐LLP2A in some time‐ points. The tumor‐to‐blood ratios of Al18F and 68Ga radiolabeled tracers were 2.8 ± 0.4 vs 3.3 ± 0.4 at 1 h, and 5.1 ± 0.9 vs 7.3 ± 0.6 at 2 h, respectively. When treating with cold LLP2A ligand, the uptake in tumor were significantly decreased, showing high affinity to VLA‐4 receptors. Conclusions Both Al18F and 68Ga radiolabeled NOTA‐PEG4‐LLP2A tracers exhibited high affinity to VLA‐4 receptors, making them good tracers for imaging melanoma. The performance of [68Ga]Ga‐NOTA‐PEG4‐LLP2A was slightly superior to those of [18F]AlF‐NOTA‐PEG4‐LLP2A. Considering of the availability of both radionuclide and the in vitro and in vivo performance, both tracers hold promising potential for clinical translation. ACKNOWLEDGEMENT This work was supported by the National Natural Science Foundation of China (nos. 81630049 and 81801738).
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Radiolabeled compounds ‐ oncology (imaging) session 3 O-67 |
18
F‐labelled click based PSMA‐tracer for prostate cancer imaging
Verena Bohmer1; Dion van der Born2; Wiktor Szymanski3; Ines Antunes3; Marten Klopstra4; Douwe Samplonius1; Jürgen Sijbesma1; Wijnand Helfrich1; Ton Visser4; Ben Feringa1; Philip Elsinga1 1
University Medical Center Groningen, Netherlands; 2 FutureChemistry
Holding B.V., Netherlands; 3 UMCG, Netherlands; 4 Syncom, Netherlands
Introduction Positron emission tomography (PET)‐imaging of prostate cancer exploiting small heterodimeric PSMA inhibitors, such as [68Ga]PSMA‐11 or [18F]PSMA‐1007, has emerged tremendously over the last few years.1 These PSMA inhibitors were also coupled to other radionuclides and imaging agents.2 However, the latter required marked structural changes that may negatively influence the binding sites of these inhibitors. Therefore, a versatile
click‐based synthesis route was developed for the production of PSMA inhibitor‐based tracers suitable for various applications, including optical imaging, photodynamic therapy and radionuclide therapy, without changing the main structure of the PSMA‐binding sites. Using this approach, the novel fluorine‐18 tracer designated [18F] PSMA‐VB01 was produced and compared with the clinically used [68Ga]PSMA‐11. Methods A synthesis route for [18F]PSMA‐VB01 was established by retro‐synthesis. After successful manual synthesis, the fluorine‐18 radiolabeling was automated using the FlowSafe continuous‐flow micro‐reactor platform. Both the building blocks VB01‐S1 and [18F]fluoride were azeotropically dried, dissolved in dry acetonitrile and transferred through a 100 μL micro‐reactor at a flow of 80 mL/min resulting in an effective reaction time of 75 s and an overall time of 17 min for complete transfer of both solutions through the micro‐reactor. [18F]VB01‐S1 was purified using a solid phase extraction cartridge and eluted with DMSO into a vial containing the pre‐dissolved acetylene‐PSMA‐binding ligand and click reagents in H2O. The mixture was left to react for 20 min at 90oC.
Overview of the results obtained for the fluorine‐18 labeling of the novel tracer [18F]PSMA‐VB01. A) Synthesis route of the novel tracer [ F]PSMA‐VB01, which was synthesized in a radiochemical yield of 21% decay corrected from the beginning of the radiolabeling with a total synthesis time of 148 min. B) Results of the in vitro experiments on LNCaP cells with different concentrations of F‐PSMA‐VB01 (short F‐PSMA1) and the precursor PSMA‐HBED‐CC (precPSMA‐HBED‐CC) against the clinically used [68Ga]PSMA‐11 showing similar binding affinities. C) Preliminary results of the in vivo studies (n = 4) showing tumor uptake of 14.2 ± 2 %ID/g
FIGURE 1
18
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[18F]PSMA‐VB01 was purified using HPLC and formulated. The IC50 value of the purified tracer was assessed in vitro using PSMA‐expressing LNCaP cancer cells. Moreover, in vivo imaging studies were performed using BALBc nude mice bearing a LNCaP xenograft. Results The novel [18F]PSMA‐VB01 was successfully synthesized. Automation using microfluidics led to less side‐ products, which simplified purification and led to a higher radiochemical yield. The synthesis was performed with an overall radiochemical yield of 21% and a molar activity of 14.1 ± 12 GBq/mmol (Figure 1A). The partition coefficient was ‐0.4. In vitro study with bench mark agent [68Ga]PSMA‐11 showed an IC50 of 49.2 ± 32 nM for F‐ PSMA‐VB01 compared to 66.6 ± 34 nM for PSMA‐ HBED‐CC, the precursor of [68Ga]PSMA‐11 (Figure 1B). Biodistribution data at 105 min p.i. show an tumor uptake of the radiotracer of 14.2 ± 2 %ID/g, which is higher than the reported uptake of 4.9 ± 1 %ID/g of the clinically used [68Ga]PSMA‐11 on the same tumor model.3 The tumor is clearly visible in the mPET‐image (Figure 1C). Conclusion A novel [18F]PSMA‐VB01 PCa tracer was successfully synthesized. The in vitro and in vivo results show good binding properties towards PSMA‐expressing cancer cells. Further research is warranted to determine possible metabolite‐formation and compare PSMA binding specificity of [18F]PSMA‐VB01 with [68Ga]PSMA‐11. R EF E RE N C E S 1. Czarniecki, M. et al. Keeping up with the prostate‐specific membrane antigens (PSMAs): an introduction to a new class of positron emission tomography (PET) imaging agents. Transl. Androl. Urol. 7, 831–843 (2018). 2. Wang, X. et al. Theranostic agents for photodynamic therapy of prostate cancer by targeting prostate‐specific membrane antigen. Mol. Cancer Ther.(2016). doi:https://doi.org/10.1158/1535‐7163. MCT‐15‐0722 3. Baranski, A.‐C. et al. Improving the imaging contrast of 68Ga‐ PSMA‐11 by targeted linker design: charged spacer moieties enhance the pharmacokinetic properties. Bioconjug. Chem. 28, 2485–2492 (2017).
Radiolabeled compounds ‐ oncology (imaging) session 3 O-68 | Preclinical evaluation of [18F]DiFA, a novel hypoxia PET probe, in a rat intracranial glioma model Hironobu Yasui1; Kei Higashikawa1; Yuki Shibata2; Hiroki Matsumoto3; Tohru Shiga4; Nagara Tamaki5; Yuji Kuge1
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Hokkaido University, Japan; 2 Graduate School of Biomedical Science
and Engineering, Hokkaido University, Japan; 3 Nihon Medi‐Physics Co, Ltd, Japan; 4 Graduate School of Medicine, Hokkaido University, Japan; 5
Department of Radiology, Kyoto Prefectural University of Medicine, Japan
Objectives Glioblastoma is the most frequent primary malignant brain tumor and its malignant natures such as radio/chemo‐resistance and metastasis are closely associated with hypoxia. A nitroimidazole derivative, [18F]‐ fluoromisonidazole ([18F]FMISO) can accumulate specifically in the hypoxic cells and is expected as a promising PET imaging agent. However, the slow clearance of [18F] FMISO from normal tissue causes a problem that it takes relatively long time to obtain good contrast images of the tumor hypoxia. In this study, we assessed the validity of a new [18F]FMISO‐based derivative with higher hydrophilicity, 1‐(2,2‐dihydroxymetyl‐3‐[18F]‐fluoropropyl)‐2‐ nitroimidazole ([18F]DiFA, formerly reported as [18F]‐ HIC101, Figure 1) as a hypoxic probe in comparison with [18F]FMISO by investigating their intratumoral distribution in a rat intracranial glioma model. Methods The rat glioma cell line C6 was used for evaluation. For intracranial implantation, tumor cells (5 × 105 cells) in a total volume of 10 μL were injected at 2.0 mm anterior and 2.0 mm lateral to the bregma to a depth of 3.5 mm at a rate of approximately 2 μL/min in WKAH/Hkm rats aged 6‐9 weeks. Two weeks after cell inoculation, tumor‐bearing rats were assigned to two groups and [18F]DiFA or [18F]FMISO PET imaging was performed to each group. The static PET images were obtained using a small‐animal PET/CT equipment at 1 h and 2 h after [18F]DiFA or [18F]FMISO injection. The co‐localization of PET probe and pimonidazole, which was injected 30 min before sacrifice, in tumor tissues was examined by autoradiography (ARG) and immunohistological staining. Results [18F]DiFA clearly visualized the tumor at 1 h post injection, while [18F]FMISO showed relatively vaguely‐ delineated tumor due to the high background tissues at this time point (Fig. 2). Estimated intratumoral SUVmax values at 1 h and 2 h after [18F]DiFA injection were significantly smaller than those of [18F]FMISO (1 h: 0.55 ± 0.07 vs 1.83 ± 0.37, 2 h: 0.47 ± 0.08 vs 2.40 ± 0.25). On the other hand, obtained SUVmax ratio of tumor to normal brain tissues revealed that [18F]DiFA produced good tumor contrast compared to [18F]FMISO from early time point (1 h: 2.93 ± 0.14 vs 1.64 ± 0.20, 2 h: 4.13 ± 0.58 vs 2.03 ± 0.02). In addition, histological analysis showed a positive correlation between the localizations of [18F] DiFA visualized by ARG and pimonidazole.
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Conclusions PET study revealed rapid clearance of [18F]DiFA from normal tissue gives the advantage of early visualization of tumor tissue over [18F]FMISO. Histological analysis confirmed the property of [18F]DiFA as a hypoxic probe. These results are in good agreement with our previous study using subcutaneous tumor models. Therefore, [18F]DiFA can be applied to various types of solid tumors and enables higher contrast PET imaging for hypoxia than [18F]FMISO. ACKNOWLEDGMENTS This study was supported in part by the Creation of Innovation Centers for Advanced Interdisciplinary Research Areas Program of the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and by Acceleration Transformative research for Medical innovation program (ACT‐M) from the Japan Agency for Medical Research and Development (AMED). R EF E RE N C E S 1. Nakata N. et al. J Nucl Med 2012; 53(S1):1523. 2. Yasui H. et al. J Nucl Med 2017; 58(S1):680.
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Radiolabeled compounds ‐ oncology (imaging) session 3 O-69 | Dynamic PET/CT imaging of
18
F‐(2S, 4R)4‐fluoroglutamine in breast cancer patients
Xiaoxia Xu1,2,3,4,5; Hua Zhu1,2,3,4,5; Zhi Yang1,2,3,4,5 1
Hokkaido University, Japan; 2 Graduate School of Biomedical Science
and Engineering, Hokkaido University, Japan; 3 Nihon Medi‐Physics Co, Ltd, Japan; 4 Graduate School of Medicine, Hokkaido University, Japan; 5
Department of Radiology, Kyoto Prefectural University of Medicine, Japan
Abstract This preliminary clinical study evaluated the safety, biodistribution and diagnostic potential of a glutamine analog, 18F‐(2S, 4R) 4‐fluoroglutamine (18F‐FGln), in breast cancer patients. Methods Seventeen patients (Female; age 36~69y) with biopsy‐ proven breast cancer were investigated with MRI and PET/CT. All subjects underwent dynamic whole‐body PET/CT after intravenous injection of 18F‐FGln
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(3.7 MBq per kilogram), followed by a whole body 18F‐ FDG/PET performed in the same week. The PET/CT imaging characteristics of MRI, FDG/PET and FGln/PET in all lesions of 17 patients were compared. The quantitative analysis parameter in tumors and normal breast tissues were evaluated by maximal standardized uptake values (SUV). As the Ki‐67 proliferation index is presently used as the key marker of prognosis, and treatment guidelines are largely based on this index, the correlation among the Ki‐67 index, 18F‐FGln, 18F‐ FDG uptake was also investigated. Results 18 F‐FGln was well tolerated in all patients without adverse events. Normal breast tissue background was low (the average SUV was 0.88 ± 0.39), a minor uptake in normal breast was observed and reached the plateau at about 30 min after injection. Uptake of 18F‐FGln in breast tumors was rapid and the SUV was highest between 1 and 10 min after injection and then a gradual washout over time (32.7% reduction in mean tumor uptake at 60 min after injection). A three‐compartment model fitted the tracer kinetics well. Axillary lymph node lesions showed rapid uptake followed by a slower washout than in tumors. It was reasonable to conclude that an early imaging window (between 0‐30 min) provided the best visual results. Furthermore, two breast tumors, ductal carcinoma in situ and mucinous carcinoma, showed slight activity of 18F‐FGln (SUVmax < 3) at all stages. Nevertheless, there were two tumors that appeared ambiguous on the 18F‐FDG scan but clear on 18F‐FGln images. The other 13 tumors and 6 metastatic lymph
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nodes were clearly diagnosed on 18F‐FGln even though the SUVmax were lower than 18F‐FDG. The median SUVma for 18F‐FGln and 18F‐FDG were 4.54 and 6.4 respectively. Immunohistochemical staining confirmed that SUVmax of 18F‐FDG was positively correlated with Ki‐67 index(r = 0.75, p = 0.01), while 18F‐FGln was not. Conclusion Dynamic imaging of 18F‐FGln PET/CT can be useful for detection of breast cancer and metastatic lymph nodes. An early imaging window seems to provide the best visual results. This study suggested that 18F‐FGln PET imaging alone might not be enough to monitor breast cancer subtypes and its cell invasion ability. ACKNOWLEDGEMENTS This work was supported in part by grants from Beijing Natural Science Foundation Key Program (No. 7171002).
Radiolabeled Compounds ‐ Oncology (Therapy and Theranostics) O-70 | Dual radionuclide theranostic pretargeting Outi Keinanen; Rosemery Membreno; Kimberly Fung; Brian Zeglis Hunter College, USA
Objectives The goal of in vivo pretargeting is to reduce the effective radiation dose to healthy tissues by separating the
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radioactivity from the targeting vector, injecting the former only when the latter has reached its target and cleared from the blood, and allowing the two to combine in the body. Pretargeting has proven especially promising in the context of nuclear imaging and targeted radiotherapy with vectors with slow pharmacokinetic profiles such as antibodies.1 In the work at hand, we sought to explore the possibility of developing an antibody‐based theranostic pretargeting platform based on the bioorthogonal ligation between tetrazine (Tz) and trans‐cyclooctene (TCO) and the sequential administration of two different radiolabeled tetrazines. Methods TCO‐modified huA33 antibody (100 μg, 0.67 nmol, 2.4 TCO/mAb) was administered i.v. to SW1222 tumor‐ bearing mice 24 h prior to the injection of [64Cu]Cu‐ SarAr‐Tz (10.4‐11.1 MBq, 0.68‐0.73 nmol). Six hours after the administration of [64Cu]Cu‐SarAr‐Tz, [177Lu]Lu‐ DOTA‐PEG7‐Tz (6.2‐6.3 MBq, 0.65‐0.67 nmol) was administered i.v. to the same mice (Figure 1A). PET imaging was carried out at 6, 24, and 48 h after the injection of [64Cu]Cu‐SarAr‐Tz. At 4, 24, 48, and 120 h after the injection of [177Lu]Lu‐DOTA‐PEG7‐Tz, the mice were sacrificed, and their organs were collected, weighed, and measured with gamma counter. Results Similar biodistribution profiles were observed for both radiotracers, confirming that pretargeted PET imaging
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and radioimmunotherapy can be achieved via the sequential administration of tetrazine radioligands (Figure 1B). At early time points, small differences were seen in the uptake of [64Cu]Cu‐SarAr‐Tz and [177Lu]Lu‐DOTA‐ PEG7‐Tz in the tumor and blood. This is likely due to the six‐hour interval between the administration of the two radiotracers, which would have a larger effect at the earliest time points. Conclusions We have successfully demonstrated the efficacy of in vivo pretargeting with two successive injections of tetrazine radiotracers. Based on our results, theranostic pretargeted PET imaging could be used to estimate the optimal time point for the administration of a radiotherapeutic dose to the same individual. Furthermore, this method of sequential injections could also be applied to the administration of fractioned doses in pretargeted radioimmunotherapy. ACKNOWLEDGEMENTS We are very grateful to the National Institutes of Health (U01CA22104) for their support. The MSKCC Small Animal Imaging Core Facility and Radiochemistry and Molecular Imaging Probe Core, which were supported by NIH grant P30 CA08748 and S10 RR020892‐01, are also acknowledged.
RE FER EN CE 1. Stéen, E. et al. 2018. Biomaterials, 179, 209‐245.
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Radiolabeled compounds ‐ oncology (therapy and theranostics) O-71 | [68Ga]/[177Lu]P17‐087: A potential theranostic agent targeting PSMA expressing tumor Hank Kung1; Seok Rye Choi2; Zzhihao Zha1; Karl Ploessl1; David Alexoff3 1
University of Pennsylvania, USA; 2 Five Eleven Pharma, USA; 3 Five
Eleven Pharma Inc, USA
Objectives Prostate specific membrane antigen (PSMA) targeting imaging agents have successfully demonstrated clinical utility in the diagnosis of primary and biochemical recurrent (BCR) prostate cancer with higher tumor detection rate compared to choline PET/CT and radiological conventional imaging. In addition to diagnostic applications, PSMA targeting agents can be used for theranostic endoradiotherapy with therapeutic nuclides (e.g., 177Lu and 225Ac). [177Lu]PSMA‐617 is now under phase III clinical trials, and it may soon be approved for treatment of prostate cancer. Previously, we reported a new PSMA targeting imaging agent, [68Ga]P16‐093, [68Ga]Glu‐NH‐CO‐NH‐Lys (Ahx)‐linker‐HBED‐CC conjugate with a novel O‐(carboxymethyl)‐L‐tyrosine, as the linker group (Figure 1).1 [68Ga]P16‐093 was proved to be a useful imaging agent and is now in early phase II clinical trial. To develop theranostic agents, we prepared and evaluated several new DOTA‐based derivatives with the same linker of P16‐093. One of which, [177Lu]P17‐087 is found to be a promising candidate as a theranostic agent for the imaging and therapy of prostate cancer.
TABLE 1
Methods Preparation of “cold” ligands, P17‐087, [natGa]P17‐087 and [natLu]P17‐087 complexes were accomplished and characterized similar to that of [natGa]P16‐093.1 Radiolabeling of P17‐087 and PSMA‐617 with [177Lu] and [68Ga] were performed in acetate buffer (pH 4.5) at 90 °C for 10‐20 min. The radiochemical purity was >95% as detected by HPLC. Binding affinity to PSMA was determined by in vitro competition‐binding assay against [125I]MIP‐1095. Biodistribution studies were conducted in nude mice bearing PSMA positive PIP‐PC3 and PSMA negative PC3 tumor xenografts. Results In vitro binding studies using PSMA‐overexpressing cell membrane homogenates showed that “cold” PSMA‐617, P17‐087, [natGa]P17‐087, and [natLu]P17‐087 complexes displayed excellent binding affinities (IC50 = 7, 15, 22, and 19 nM, respectively). Radioactive [68Ga]P17‐087, [177Lu]P17‐087, [68Ga]PSMA‐617, and [177Lu]PSMA‐617 were prepared and the radiochemical purities were >95%. In vivo biodistribution studies were performed in mice implanted with PIP‐PC3 (PSMA positive) and PC3 (PSMA negative) cells. At one hour post iv injection the PSMA positive tumor showed high uptake (13.9 ± 1.5, 15.3 ± 2.9, 10.1 ± 1.8 and 11.4 ± 2.8% dose/g for [68Ga] P17‐087, [177Lu]P17‐087, [68Ga]PSMA‐617 and [177Lu] PSMA‐617, respectively). Comparison between [177Lu] P17‐087 and [177Lu]PSMA‐617 in the same PIP‐tumor mouse model showed similar uptakes at 1 hr and 4 hr for both agents (Table 1). Furthermore, [177Lu]P17‐087 exhibited an extended PSMA positive tumor retention (tumor activity was 15.3 ± 2.9, 22.4 ± 3.5, 11.3 ± 2.6, 14.0 ± 6.4, 6.9 ± 1.9 and 4.2 ± 1.0% dose/g at 1, 4, 24, 48, 96, and 192 hr, respectively). Beside tumor uptake, physiological tracer uptake was seen in kidneys and spleen, with [177Lu]P17‐087 showing higher kidney
Comparison of biodistribution in tumor bearing nude mice (% dose/g, n = 4) 1 hr 68
4 hr 177
[ Ga]
[
Lu]
68
[ Ga]
[
177
Lu]
[177Lu]
[177Lu]
PSMA‐617
PSMA‐617
P17‐087
P17‐087
PSMA‐617
P17‐087
Blood
0.44 ± 0.11
0.16 ± 0.03
0.65 ± 0.08
0.27 ± 0.07
0.02 ± 0.00
0.02 ± 0.01
Kidney
25.6 ± 31.5
21.8 ± 10.6
166.3 ± 18.6
45.6 ± 20.5
5.07 ± 0.74
21.2 ± 5.08
Liver
1.94 ± 0.57
0.15 ± 0.04
2.87 ± 0.30
0.18 ± 0.05
0.12 ± 0.01
0.09 ± 0.03
Bone
0.09 ± 0.03
0.14 ± 0.15
0.17 ± 0.01
0.15 ± 0.05
0.03 ± 0.01
0.05 ± 0.01
Muscle
0.11 ± 0.03
0.11 ± 0.06
0.21 ± 0.05
0.18 ± 0.06
0.02 ± 0.01
0.05 ± 0.01
PIP‐PC3
10.1 ± 1.8
11.4 ± 2.8
13.9 ± 1.5
15.3 ± 2.9
18.0 ± 2.8
22.4 ± 3.5
PC3
0.50 ± 0.30
0.70 ± 0.19
1.14 ± 0.25
1.13 ± 0.61
0.34 ± 0.06
0.28 ± 0.08
PIP‐PC3 tumor (PSMA positive) cells and PC3 tumor (PSMA negative) cells were implanted in the same mouse.
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uptake at 4 hr compared to [177Lu]PSMA‐617. [177Lu]P17‐ 087 showed good stability in vitro and in vivo. No metabolites were observed in plasma of mouse at 2 hr post‐ injection. Results suggest that [177Lu]P17‐087 proved to have comparable PSMA binding specificity and PSMA positive tumor uptakes in vivo to those of [177Lu]PSMA‐ 617, a theranostic ligand currently in clinical evaluation. Also, [68Ga]P17‐087 showed in vitro and in vivo characteristics similar to [177Lu]P17‐087. Conclusions In summary, [68Ga]/[177Lu]P17‐087 is a promising candidate for further development as a theranostic agent for the imaging and therapy of metastatic castration‐resistant prostate cancer.
R EF E RE N C E 1. Zha Z, Ploessl K, Choi SR, Wu Z, Zhu L, and Kung HF. Synthesis and evaluation of a novel urea‐based 68Ga‐complex for imaging PSMA binding in tumor. Nucl. Med. Biol. 2018; 59:36‐47.
Radiolabeled compounds ‐ oncology (therapy and theranostics) O-72 | Selection of the optimal macrocyclic chelators for labelling with 111In and 68Ga improves contrast of HER2 imaging using engineered scaffold protein ADAPT6 Vladimir Tolmachev1; Sarah Lindbo2; Mohamed Altai1; Emma von Witting2; Anzhelika Vorobyeva1; Maryam Oroujeni1; Bogdan Mitran1; Anna Orlova1; Javad Garousi1; Sophia Hober2 1
Uppsala University, Sweden; 2 KTH, Royal Institute of Technology,
Sweden
Objectives ADAPTs are small (molecular weight 5‐7 kDa) engineered targeting proteins developed using the scaffold of the albumin‐binding domain of protein G. ADAPT6, which specifically binds to human epidermal
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growth factor 2 (HER2), has demonstrated capacity to provide high‐contrast imaging of HER2‐expressing tumour xenografts in mice. Literature data for short peptides and other engineered scaffold proteins show that a combination of a radionuclide and a chelator influence off‐target interactions and, in this way, imaging contrast. In this study, we compared tumour‐targeting properties of ADAPT6 variants, which were site‐specifically labelled with 68Ga or 111In using the macrocyclic chelators NOTA, NODAGA, DOTA and DOTAGA. The goal was to select the variant(s) providing highest tumour‐to‐organ ratios and, in this way, the highest sensitivity in imaging of small metastases. Methods ADAPT6 variants having a single cysteine at C‐terminus were produced recombinantly and conjugated with maleimido‐monoamino derivatives of macrocyclic chelators NOTA, NODAGA, DOTA and DOTAGA. Labelling with 68Ga was performed in 1.25 M sodium acetate, pH 3.5 (95°C, 15 min). Labelling with 111In was performed in 0.2 M ammonium acetate, pH 6.5 (95°C, 30 min). The labelled conjugates were purified using NAP‐5 cartridges. In vitro specificity and cellar processing of the radiolabelled conjugates were evaluated using HER2‐expressing SKOV‐3 ovarian carcinoma cell line. Biodistribution of radiolabelled conjugates was measured in BALB/C nu/nu mice bearing SKOV‐3 xenografts at 3 h and 24 h (only for 111In) after injection. HER2‐negative Ramos xenografts were used as specificity control. Results Mass‐spectrometry data for all conjugates were in excellent agreement with the theoretical molecular weights. The molar activity of the radiolabelled conjugates was over 14.6 GBq/μmol. The radiochemical purity was over 98%. No measurable release of radionuclides was detected after challenge with 500‐molar excess of EDTA. Binding of all conjugates to cancer cell‐lines in vitro was HER2‐specific. In vivo, all conjugates were cleared rapidly from blood via kidneys with subsequent renal reabsorption (Table 1), which resulted in high kidney uptake. Clinical experience with affibody molecules having similar biodistribution patter demonstrated that
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TABLE 1
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Uptake of radiolabelled ADAPT6 variants. Data presented as average with standard deviation (n = 4) NOTA‐ADAPT6
NOGAGA‐ADAPT6
DOTA‐ADAPT6
DOTAGA‐ADAPT6
Uptake (%ID/g) 111
In; 3 h
Blood
0.62 ± 0.10
0.49 ± 0.05
0.13 ± 0.02
0.17 ± 0.01
Kidney
351 ± 60
372 ± 46
350 ± 21
387 ± 14
19.8 ± 5.3
13.2 ± 1.5
14.6 ± 2.3
13.8 ± 1.7
Tumour
68
Ga; 3 h
Blood
0.25 ± 0.05
0.12 ± 0.02
0.20 ± 0.02
0.19 ± 0.01
Kidney
365 ± 63
376 ± 45
338 ± 21
379 ± 9
19.2 ± 53
12.7 ± 1.4
12.8 ± 2.0
12.6 ± 1.6
Tumour
111
In; 24 h
Blood
0.16 ± 0.02
0.11 ± 0.03
0.03 ± 0.01
0.05 ± 0.01
Kidney
257 ± 31
281 ± 56
283 ± 49
300 ± 13
Tumour
9.2 ± 0.5
10.4 ± 2.5
10.2 ± 3.7
11.2 ± 1.3
Figure. Selected tumour‐to‐organ ratios for ADAPT6 variants labelled with 111In at 3 h (A) and 24 h (C) and with 68Ga at 3 h (B). Data presented as average and standard deviation (n = 4) the high renal uptake does not prevent imaging of metastases in lumbar area. Uptake of all variants in HER2‐ positive tumours was much higher than in HER2‐ negative (p < 0.0005), which demonstrates high HER2‐ specificity. There was no significant difference between uptakes of all variants in HER2‐positive xenografts at 3 h p.i. In the case of 68Ga, the clearance of conjugates labelled using triaza chelators (NOTA and NODAGA) from blood and normal tissues was rapider than clearance of conjugates labelled using tetraaza chelators (DOTA and DOTAGA). Accordingly, these chelators provided higher tumour‐to‐organ ratios. For 111In, the tetraza chelators provided rapider clearance and higher tumour‐to‐organ ratios. Conclusions The combination of a radionuclide and a macrocyclic chelator has strong influence on off‐target interaction of ADAPT‐based imaging probes. Selection of an optimal combination enables selection of a variant providing the highest imaging contrast. Among 68Ga‐labelled variants,
NODAGA‐ADAPT6 provided the best tumour‐to‐organ ratios for blood, muscles and major metastatic sites (lung, liver and bone). For 111In label, DOTA‐ADAPT6 provided the best tumour‐to‐organ ratios. This study shows that selection of optimal labelling chemistry might not only provide stable coupling of nuclide to a targeting protein, but can improve sensitivity of imaging.
Radiolabeled compounds ‐ oncology (therapy and theranostics) O-73 | A Metabolically stable boron‐derived tyrosine serves as a theranostic agent for positron emission tomography guided boron neutron capture therapy Jiyuan Li1; Yaxin Shi; Zizhu Zhang2; Tong Liu2; Xiaoyuan Chen3; Zhibo Liu1
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Peking University, China; 2 Beijing Capture Tech (BCTC), China;
3
NIBIB/CC/NIH, USA
Objectives Boronophenylalanine (BPA) is the dominant boron delivery agent for boron neutron capture therapy (BNCT), and [18F]FBPA has been developed to assist the treatment planning for BPA‐BNCT. However, the clinical application of BNCT has been limited by its inadequate tumor specificity due to metabolic instability. In addition, the distinction on the molecular structure between [18F]FBPA and BPA is also a concern that [18F]FBPA cannot quantitate boron concentration of BPA in a real‐time manner. In this study, a metabolically stable boron‐derived tyrosine, denoted as fluoroboronotyrosine (FBY), was developed as a theranostic agent for both boron delivery and cancer diagnosis, leading to PET imaging guided BNCT of cancer.
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Methods [18F]FBY was radiolabeled through 18F‐19F isotope exchange reaction. Computational studies and competitive inhibitory assay were conducted to study the mechanism of cellular uptake of FBY. Stability of FBY was monitored by HPLC. In vivo small‐animal [18F]FBY PET imaging and biodistribution studies were conducted. The correlation between PET image and boron concentrations of tumor and major organs was studied under the condition of injection with the mixture of trace amount of [18F]FBY along with therapeutic dose of FBY. At last, the effectiveness of FBY‐BNCT was evaluated on mice bearing B16‐F10 tumors. Results [18F]FBY was synthesized in high radiochemical yield (50%) and high radiochemical purity (98%). FBY showed high similarity with natural tyrosine. The uptake of FBY
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in B16‐F10 cells was LAT‐1 dependent and reached up to 128 ppm. FBY displayed high stability. [18F]FBY PET showed high accumulation in the tumor and notably low normal tissue uptake (Tumor/Muscle = 3.16 ± 0.48; Tumor/Blood = 3.13 ± 0.50; Tumor/Brain = 14.25 ± 1.54). Moreover, administration of [18F]FBY tracer along with therapeutic dose of FBY showed high‐specific accumulation in the tumor and low normal tissue uptake. correlation between PET‐image and boron biodistribution was established, indicating the possibility to estimate boron concentration via non‐invasive approach. At last, neutron irradiation with FBY showed excellent tumor control without exhibiting obvious systemic toxicity. Conclusion FBY‐BNCT provides excellent control over the growth of B16‐F10 melanoma cancer. Moreover, FBY holds a great potential for being an efficient theranostic agent for imaging‐guided BNCT for brain tumor and lung metastases by offering a possible solution of measuring local boron concentration via PET imaging.
Radiolabeled Compounds ‐ Oncology (Therapy and Theranostics) O-74 | Barium ferrite magnetic nanoparticles labeled with 223Ra: A new potential magnetic radiobioconjugate for targeted alpha therapy Aleksander Bilewicz1; Edyta Cedrowska1; Weronika Gawęda1; Frank Bruchertseifer; Alfred Morgenstern2 1
Instutute of Nuclear Chemistry and Technology, Poland; 2 Institute for
Transuranium Elements, Germany 223
Ra, as radium chloride, is the first commercially and widely used α‐radiopharmaceutical. It is easily obtained from the 227Ac/223Ra generator. However, 223Ra is used only for treatment of bone metastases derived from primary prostate and breast cancers. Unfortunately, the lack of an appropriate bifunctional ligand for radium was the reason why 223Ra has not yet found application in receptor targeted therapy. Because Ra2+ and Ba2+ are nearly identical cations in our studies we propose to use barium ferrite (BaFe12O19) nanoparticles as multifunctional carriers for 223Ra radionuclide for targeted α therapy. Results and methods Barium hexaferrite nanoparticles labelled with 223Ra were synthesized by a modified autoclave method described by Drofenik et al [1]. The reaction mixture of FeCl3, BaCl2 and 223RaCl2 was alkalized with NaOH solution. Next, the reaction mixture was stirred in autoclave at 210oC for 6 h. Obtained radioactive, magnetic [223Ra]BaFe12O19 nanoparticles were washed with distilled water and
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hydrochloric acid (0.001 M HCl). Obtained magnetic BaFe12O19 nanoparticles were characterized by transmission emission microscopy and dynamic light scattering. The diameter of synthesized nanoparticles was ~20 nm and the determined magnetization of nanoparticles in room temperature was about 42 emu/g. Yield of labelling was about 70% (for 100 kBq 223Ra). Stability of the obtained radioactive nanoparticles was tested in various biological solutions: 0.01 M PBS, 0.9% NaCl and in human blood serum. It is confirmed that 223Ra was highly retained inside nanoparticles in every tested solution. Only about 20% of 211Pb (recoiled decay product of 223Ra) was found in solution. In order to synthesize a radiobioconjugate having affinity to HER2 receptors, the monoclonal antibody trastuzumab was conjugated to the obtained barium ferrite nanoparticles. Firstly, the surface of barium ferrite nanoparticles was modified with 3‐phosphonopropionic acid linker using a method described by Mohapatra et al [2], and then, the monoclonal antibodies were coupled to the barium ferrite nanoparticles using the carbodiimide chemistry. Synthesized bioconjugate was characterized by thermogravimetric analysis, dynamic light scattering and were tested for stability in biological fluids. The obtained [223Ra] BaFe12O19‐CEPA‐trastuzumab radiobioconjugate almost quantitatively retains 223Ra and majority of the daughter products. In‐vitro biological studies indicate that [223Ra] BaFe12O19‐CEPA‐trastuzumab exhibits high affinity and cytotoxicity to the to the SKOV3 ovarian cell line. Conclusions We have shown that radium ferrite nanoparticles labelled with 223Ra and functionalized with trastuzumab presents a prospective solution for the use of the 223Ra as a therapeutic tool for targeting HER2 positive breast and ovarian cancers. ACKNOWLEDGEMENT This work was supported by National Science Centre of Poland by Grants NCN Preludium 2015/17/N/ST4/03943 and Opus 2016/21/B/ST4/02133. RE FER EN CE 1. Drofenik M, et al. Mat.Chem.Phys. 2011; 127: 415–419 2. Mohapatra S, et al. Nanotechnology 2007; 18: 385102–11
Radiolabeled Compounds ‐ Oncology (Therapy and Theranostics) O-75 | Photodynamic therapy with a CD276‐targeted agent for enhancing tumor anti‐PD‐1/PD‐L1 immune checkpoint inhibition Bao Rui1; Yanpu Wang2; Lai Jianhao1; Zhaofei Liu3; Fan Wang3
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Medical Isotopes Research Center and Department of Radiation
Medicine, School of Basic Medical Sciences, Peking University Health Science Center, China; 2 Medical Isotopes Research Center, Peking University, China; 3 Peking University, China
Objectives Antiangiogenic therapies have been demonstrated to reverse the immunosuppressive status of the tumor microenvironment and thus improve the efficacy of immunotherapy. However, most of current antiangiogenic agents cannot discriminate tumor angiogenesis from physiological angiogenesis. CD276 is a receptor overexpressed in various tumor cells and tumor vasculature but not in normal tissue vasculature. Herein, we aimed to develop a tumor cell and vasculature CD276‐specific photodynamic therapy (PDT) agent and investigated whether this PDT agent could be used in combination with PD‐1/PD‐L1 blockade for the effective treatment of primary tumors as well as ablation of tumor metastases. Methods A CD276‐targeting agent (denoted as IRD‐αCD276/Fab) was synthesized by conjugating the Fab fragment (αCD276/Fab) of an anti‐CD276 antibody with the
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photosensitizer IRDye700. To evaluate the distribution of IRD‐αCD276/Fab in mice, small‐animal optical imaging with IRD‐αCD276/Fab and PET/CT imaging with 64 Cu‐labeled αCD276/Fab were performed. The therapeutic effect of IRD‐αCD276/Fab‐based PDT with or without anti‐PD‐1/PD‐L1 blockade was tested in 4T1 and firefly luciferase stably transfected 4T1 (4T1‐fLuc) tumor mouse models. Results The tumor uptake of IRD‐αCD276/Fab was significantly higher than that of the IRD‐IgG/Fab control (e.g., 10.27 ± 1.16% vs. 4.05 ± 0.34% at 2 h p.i.; P < 0.001), demonstrating that IRD‐αCD276/Fab was specific for CD276 in the tumor. The results of optical imaging were further verified by evaluating the in vivo behavior of the radiolabeled counterpart 64Cu‐αCD276/Fab by PET/CT. PDT using IRD‐αCD276/Fab significantly inhibited the growth of subcutaneous 4T1 tumor and its metastasis to the lung. Moreover, it triggered antitumor immunity by increasing the activation and maturation of dendritic cells in vivo. Tumor PD‐L1 levels were also significantly increased after PDT using IRD‐αCD276/Fab, as evidenced by noninvasive PD‐L1‐targeted small‐animal
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PET imaging and biodistribution of 124I‐αPD‐L1 (14.82 ± 3.25 %ID/g vs. 6.56 ± 1.56 %ID/g; P < 0.01). In combination with anti‐PD‐1 or anti‐PD‐L1 treatment, IRD‐αCD276/Fab PDT markedly suppressed tumor growth and prevented lung metastasis by increasing the infiltration of CD8+ T cells into the tumor. Conclusions We demonstrated that CD276‐targeted photodynamic ablation of tumor cells and tumor vasculature enables upregulation of PD‐L1 in tumors, thereby increasing the antitumor efficacy of PD‐1/PD‐L1‐targeted immune checkpoint inhibitory therapy. Combination of CD276‐ targeted PDT with PD‐L1/PD‐1 pathway inhibition is a promising strategy for eliminating primary tumors as well as disseminated metastases, by generating local and systemic antitumor responses.
Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-76 | Synthesis of photoactivatable HBED‐CC and immunoPET of the hepatocyte growth factor receptor c‐MET using photoradiolabelled [68Ga]GaHBED‐CC‐MetMAb Rachael Fay1; Melanie Gut2; Jason Holland2 1
University of Zurich, Switzerland; 2 Department of Chemistry, University
of Zürich, Switzerland
Objectives Amplification of the hepatocyte growth factor receptor (c‐MET) has been identified as a biomarker in various human cancers.1 The genetically engineered one‐armed scFv‐FC antibody fragment MetMAb (Ornatuzumab) was designed to block hepatocyte growth factor (HGF) binding and inhibit c‐MET signalling by interacting with the extracellular domain of c‐MET. Development of an immunoPET agent based on MetMAb has the potential to characterise c‐MET expression in tumours.2,3 In a novel approach for radiotracer design, we synthesised a photoactivatable derivative of the chelate HBED‐CC and used a two‐step photochemical conjugation and radiolabelling approach to produce [68Ga]GaHBED‐CC‐ azepin‐MetMAb. ImmunoPET imaging of the c‐Met biomarker was investigated in tumour‐bearing mice. Methods The HBED‐CC‐arylazide derivative was synthesised in seven linear steps starting from methyl 3‐(4‐ hydroxyphenyl)propionate. Photochemical conjugation MetMAb was of HBED‐CC‐PEG3‐propyl‐ArN3to
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accomplished by irradiation at 365 nm for 10 min at pH >8. The desired conjugate was purified by centrifugal filtration and subsequently radiolabelled with 68Ga (0.25 M NaOAc, pH 4.4, 23 °C). The immunoreactive fraction was determined in vitro using two different cell lines with either high (MKN‐45) or moderate‐to‐low (PC‐3) c‐Met expression. Athymic nude mice were injected subcutaneously on the right shoulder with either MKN‐45 (female, gastric) or PC‐3 cells (male, prostate). The pharmacokinetics and tumour binding of [68Ga]GaHBED‐CC‐azepin‐ MetMAb were investigated in vivo in both tumour models. Animals were administered 0.5 nmol (Am = 22.3 MBq/ nmol) of 68GaHBED‐CC‐azepin‐MetMAb viatail vein injection. A competitive blocking study in the MKN‐45 tumour line was also conducted using a reduced molar activity formulation (10.5 nmol total protein, Am = 1.26 MBq/nmol). PET images were recorded up to 6 h post injection and then biodistribution studies were performed. Results Photochemical conjugation of HBED‐CC‐arylazide to MetMAb was achieved with a photochemical efficiency of 18.5 ± 0.5% (n = 2). Purified [68Ga]GaHBED‐CC‐ azepin‐MetMAb was obtained with a radiochemical purity >95% (Size‐exclusion chromatography), a molar activity of Am = 35.8 MBq/nmol of protein, and an isolated radiochemical yield of 55%. Standard Lindmo assays confirmed remained that [68Ga]GaHBED‐CC‐azepin‐MetMAb immunoreactive and bound specifically to both MKN‐45 and PC‐3 cells. Radiotracer uptake in high c‐MET expressing MKN‐45 tumours was 10.33 ± 1.27 %ID/g (n = 5) and in lower c‐MET expressing PC‐3 models only 3.88 ± 1.27 %ID/g (n = 3, Student's t test P value < 0.001). The competitive blocking study, confirmed that [68Ga] GaHBED‐CC‐azepin‐MetMAb bound specifically to c‐ MET with MKN‐45 tumour uptake reduced by approximately 55% (4.62 ± 0.67 %ID/g, n = 5, P value < 0.001). Conclusions Unlike traditional thermochemically mediated conjugation methods which often require extended incubation times, photochemical conjugation of HBED‐CC‐PEG3‐ propyl‐ArN3to MetMAb was achieved in ~10 min. Subsequent radiochemical, cellular and in vivo experiments confirmed the viability and specificity of the [68Ga] GaHBED‐CC‐azepin‐MetMAb radiotracer as a potential tool for measuring changes in c‐MET expression in various cancers. ACKNOWLEDGEMENTS J.P.H thanks the Swiss Cancer League (Krebsliga Schweiz; KLS‐4257‐08‐2017), the Swiss National Science Foundation (SNSF Professorship PP00P2_163683), the European Research Council (ERC‐StG‐2015, NanoSCAN – 676904), and the University of Zurich for financial support.
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A) Photochemical conjugation and radiolabelling of MetMAb. B) in showing specific accumulation of [68Ga]GaHBED‐CC‐ azepin‐MetMAb in MKN‐45 tumour bearing mice
FIGURE 1
R EF E RE N C E S 1. Organ SL, Tsao MS, Ther. Adv. Med. Oncol., 2011, 3(1), 7–19. 2. Pool M, et al., Eur. J. Nucl. Med. Mol. Imaging., 2017, 44, 1328–1336. 3. Jagoda EM, et al., J. Nucl. Med., 2012, 53(10), 1592–1600.
Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-77 | Preclinical evaluation of a 68Ga‐labeled bombesin antagonist comprising the bifunctional chelator NODIA‐Me Alexander Schmidtke; Melanie Gut1; Rachael Fay2; Jason Holland1; Samer Ezziddin3; Mark Bartholomae3 1
Department of Chemistry, University of Zürich, Switzerland; 2 University
of Zürich, Switzerland; 3 Medical Center, Saarland University, Germany
Objectives The high‐density expression of the gastrin‐releasing peptide receptor (GRPr) in common human cancers, such as prostate and breast cancer, combined with the lack of GRPr‐expression in surrounding healthy tissues make it a promising target for molecular imaging and endoradiotherapy.1 Several studies have shown that non‐internalizing radiolabeled peptide antagonists exhibit superior pharmacokinetics over their agonistic counterparts with regards to tumor accumulation and retention as well as rapid clearance from physiological organs.2 Studies by Maecke et al. suggested that the positive charge at the N terminus of the GRPr antagonist RM2, created via the cationic spacer 4‐amino‐1‐carboxymethyl‐ piperidine, is responsible for high GRPr affinity and favorable pharmacokinetics.2a These results were, at least in part, recently corroborated by Guillou et al. for a small
series of 64Cu‐labeled GRPr antagonist, in which the N‐ terminal positive charge was instead created by cationic radiometal chelates.3 In this project, the structurally related 68Ga‐labeled GRPr antagonist NODIA‐Me‐Ahx‐ JMV594 1 (Figure 1A) was developed to further elucidate the influence of positively charged radiometal chelates on GRPr affinity and pharmacokinetics. Methods The peptide conjugate 1 was prepared by automated solid‐phase peptide synthesis using standard Fmoc chemistry. Labeling of 1 with 68Ga was performed at 95°C for 15 min in sodium acetate buffer pH 4.0. The GRPr affinities of the metal‐free and natGa‐labeled conjugates of 1 and RM2 were determined by competitive cell binding studies in the human prostate cancer cell line PC‐3. The pharmacokinetics of [68Ga]Ga‐1 were evaluated in male athymic nude mice bearing PC‐3 xenografts by small‐ animal PET imaging and ex vivo biodistribution studies. Target specificity was confirmed by co‐injection of a ~100‐fold molar excess of 1. Results The bioconjugate 1 was obtained in excellent yields (94%) after purification by semi‐preparative RP‐HPLC. Quantitative radiolabeling yields were achieved in molar activities of ~20 MBq/nmol and radiochemical purities of >99%. Competitive inhibitory constants for 1, natGa‐1, RM2 and natGa‐RM2 were determined to be 0.4 ± 0.2, 1.4 ± 0.2, 1.4 ± 0.1, and 1.0 ± 0.2 nM, respectively. In small‐animal PET imaging experiments at 1 h post intravenous injection (125 pmol, ~2 MBq), GRPr‐positive PC‐3 tumors as well as the pancreas (physiologically expressing high levels of GRPr) were specifically delineated by [68Ga]Ga‐1 (Figure 1B). In biodistribution studies, tumor and pancreatic uptake were 5.43 ± 1.52 and 17.68 ± 2.34% ID/g at 1 h p.i. (Figure 1C), respectively. Target specificity was demonstrated using blocking experiments, which reduced activity accumulation in the tumor and pancreas to 2.03 ± 0.26 and 0.92 ± 0.11% ID/ g (both P < 0.0001), respectively. Excretion occurred
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predominantly via the renal route with a kidney uptake of 2.85 ± 0.11% ID/g at 1 h p.i., which was significantly increased in the blocking group (11.76 ± 2.68% ID/g). Conclusions The GRPr affinity of 1 was comparable to RM2, confirming that (1) a positive charge at the N terminus of GRPr antagonists favors GRPr binding and that (2) this charge can also be created by cationic metal chelates without the need for charged amino acid spacers. Biodistribution studies of [68Ga]Ga‐1 showed excellent tumor uptake and favorable pharmacokinetics making it a promising radiotracer for imaging of GRPr‐expressing tumors. ACKNOWLEDGEMENTS M.D.B thanks the Fonds der Chemischen Industrie for funding. J.P.H thanks the Swiss Cancer League (Krebsliga Schweiz; KLS‐4257‐08‐2017), the Swiss National Science Foundation (SNSF Professorship PP00P2_163683), the European Research Council (ERC‐StG‐2015, NanoSCAN
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– 676904), and the University of Zurich for financial support. RE FER EN CES 1. a) Gugger M, Reubi JC. Gastrin‐releasing peptide receptors in non‐neoplastic and neoplastic human breast. Am J Pathol. 1999;155:2067–2076. b) Markwalder R, Reubi JC. Gastrin‐releasing peptide receptors in the human prostate: relation to neoplastic transformation. Cancer Res. 1999;59:1152–1159. 2. a) Mansi R, Wang X, Forrer F, et al. Development of a potent DOTA‐conjugated bombesin antagonist for targeting GRPr‐ positive tumours. Eur J Nucl Med Mol Imaging. 2011;38:97–107. b) Cescato R, Maina T, Nock B, et al. Bombesin receptor antagonists may be preferable to agonists for tumor targeting. J Nucl Med. 2008;49:318–326. 3. Guillou A, Lima L, Esteban‐Gómez D, Bartholomä MD, Platas‐ Iglesias C, Delgado R, Patinec V, Tripier R. Methylthiazolyl tacn ligands for copper complexation and their BCA derivatives for bioconjugation and 64Cu radiolabeling: an example with bombesin, submitted.
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Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-78 | In‐vivo PET imaging of αvβ8‐integrin Johannes Notni; Alexander Wurzer; Florian Reichart; Oleg Maltsev; Katja Steiger; Roswitha Beck; Hans‐Juergen Wester; Markus Schwaiger; Horst Kessler Technical University Munich, Germany
αvβ8‐Integrin is one out of 8 integrins recognizing the RGD peptide sequence. However, the αvβ8 subtype is fundamentally different from the well‐known αvβ3. Natively expressed on astrocytes, αvβ8 is involved in tumor development and other pathological functions. It controls tumor cell migration and metastasis in lung, colon, and squamous cell carcinomas; activates TGFβ‐1 and triggers epithelial‐mesenchymal transition; is involved in development of fibrosis, COPD, and viral entry of viruses (Herpes simplex, Epstein‐Barr). Its expression in healthy tissues is generally very low, rendering it a promising target for oncology and beyond. However, in vivo imaging of αvβ8‐integrin was hitherto hampered by a complete lack of selective small‐molecule ligands. We developed the first selective small molecular ligand for αvβ8‐integrin, the cyclic RGD octapeptide cyclo (GLRGDLp (NMe)K), which shows a good affinity for αvβ8 (IC50 = 8 nM) and a high selectivity over other
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RGD‐binding integrins (IC50 for αvβ6 = 99 nM, for αvβ3 = 343 nM, for αvβ5, α5β1, and αIIbβ3 > 1000 nM). Using the TRAP (triazacyclononane‐triphosphinate) chelator and a simple one‐pot click‐chemistry (CuAAC) coupling protocol, we synthesized monomeric and trimeric conjugates for 68Ga labeling. The natGa‐labeled trimer showed a markedly higher αvβ8 affinity (IC50 = 0.89 nM) than the monomer (IC50 = 17 nM), determined by ELISA on immobilized integrins. Both TRAP conjugates were automatically labeled with 68Ga (400–500 MBq) for 3 min at 95°C using 2 nmol of precursor, resulting in yields of 90‐95% (decay‐corrected after SPE purification) and molar activities of 150‐250 MBq/nmol. Both 68Ga tracers were evaluated by ex vivo biodistribution and μPET imaging in tumor‐bearing mice (SCID; subcutaneous human melanoma (MeWo cells) xenografts, 60 min p.i.). The trimer showed a higher tumor uptake (1.9 ± 0.3 %ID/g) than the monomer (1.0 ± 0.3 %ID/g). Blockade with excess unlabeled resulted in a similar non‐specific background (ca. 0.25 %ID/g). Both compounds are excreted renally due to pronounced hydrophilicity (log D = –3.1 and –3,9, respectively). Uptakes in non‐tumor tissues were very low, with one exception. The trimer, but not the monomer, showed a significant (0.68 ± 0.19% ID/g) but specific (i.e., blockable) uptake in the lung. This finding is consistent with β8‐ immunohistochemistry results. While other tissues were found β8‐negative and the tumor was β8‐positive, a slight
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β8‐expression was found in the lung, which did not cause an uptake of the 68Ga‐labeled monomer but of the 68Ga‐ trimer because of its higher affinity. In dynamic μPET imaging, the trimer showed a higher uptake and slower washout from the tumor (see Figure) and a higher tumor‐to‐tissue contrast (tumor‐to‐blood: 6.7; to‐liver: 6.8; to‐muscle: 29) than the monomer (tumor‐to‐blood: 5.5; to‐liver: 6.6; to‐muscle: 24). This study confirms that multimerization is a viable concept to improve the tumor retention of integrin‐binding ligands (see Figure; a superior in‐vivo performance of TRAP‐based trimers in comparison to their monomeric analogs has been observed before for αvβ3‐ and α5β1‐integrin selective ligands). Because the trimeric 68Ga labeled peptide enabled a highly sensitive and specific PET imaging of αvβ8‐integrin expression in vivo, its translation to the clinic is imminent.
Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-79 | Trans‐cyclooctene‐functionalized PeptoBrushes with improved reaction kinetics of the tetrazine ligation for pretargeted nuclear imaging Johanna Steen1; Kamilla Nørregard2; Kerstin Johann3; Jesper Jørgensen2; Dennis Svatunek4; Alexander Birke3; Patricia Edem7; Raffaella Rossin6; Christine Seidl3; Friederike Schmid5; Marc Robillard6; Hannes Mikula4; Jesper Kristensen7; Matthias Barz3; Andreas Kjær2; Matthias Herth8 1
Department of Drug Design and Pharmacology, University of
Copenhagen, Denmark; 2 Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 3 Institute of Organic Chemistry, Johannes Gutenberg University, Germany; 4 Institute of Applied Synthetic Chemistry, Technische Universität Wien (TU Wien), Austria; 5 Institute of Physics, Johannes Gutenberg University, Germany; 6
Tagworks Pharmaceuticals, Netherlands; 7 Department of Drug Design
and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 8 Univesity of Copenhagen, Sweden
Objectives Pretargeting strategies for nuclear imaging using nanomedicines offer the potential to improve imaging contrast and lower the absorbed radiation burden compared to conventional approaches. The bioorthogonal tetrazine ligation is an ideal strategy to use for pretargeting.1 The majority of reported pretargeting studies based on this ligation have used TCO‐functionalized monoclonal antibodies as targeting vectors in combination with a radiolabeled tetrazine. The objective of
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the present study was to explore a TCO‐functionalized polymeric targeting vector possessing passive tumor accumulation via the enhanced permeability and retention (EPR) effect. Such a targeting vector would allow for a higher degree of TCO‐functionalization per particle, which in turn may improve reaction kinetics. In particular, we were interested in using biocompatible copolymers based on a polyglutamic acid (pGlu) backbone grafted with polysarcosine (pSar) side chains. Methods The polymers were synthesized by ring‐opening polymerization of benzoyl‐protected N‐glutamic acid carboxyanhydride, followed by deprotection to afford a pGlu backbone. Afterward, the backbone was functionalized with TCO‐moieties and grafted with pSar side chains. The reaction kinetics of the polymers in the tetrazine ligation was determined by reaction with fluorogenic “turn‐on” tetrazines via stopped‐flow measurements.2 Radiolabeling was carried out by using a previously described 111In‐labeled DOTA‐tetrazine derivative.1 Small animal SPECT/CT imaging was performed in female BALB/c mice bearing subcutaneous colorectal mouse tumors (CT26). Results Three PeptoBrushes (Figure 1A) with different degree of TCO‐functionalization (8, 13, and 30%) were synthesized in good yields. PeptoBrush 1 with 30% TCO‐loading showed the fastest reaction kinetics in the tetrazine ligation, particularly to a lipophilic tetrazine. A second order rate constant of 427 000 M−1 s−1 was measured based on polymer concentration, which corresponds to 14 200 M−1 s−1 when normalized to the total number of TCO‐moieties. The high second order rate constants were speculated to have resulted from a hydrophobic effect and a rearrangement in the polymer chains creating hydrophobic patches (Figure 1A). PeptoBrush 1 was selected for in vivo evaluation and thus radiolabeled via ligation to the 111In‐labeled tetrazine. The labeled ligation adduct (˃99% radiochemical purity) was administered intravenously to mice. SPECT/CT image analysis revealed an EPR‐mediated tumor uptake of 5.2 ± 0.6% ID/g after 72 h. In a subsequent pretargeting study, mice were pretreated with PeptoBrush 1 72 h prior to administration of the 111In‐labeled tetrazine (Figure 1B). SPECT/CT images 2 and 22 h p.i. of the tetrazine showed a tumor uptake of 3.4 ± 0.3% ID/g and 8.1 ± 0.8% ID/g, respectively (Figure 1C). The increase in uptake between 2 and 22 h is most likely a result of the passive accumulation of still circulating PeptoBrush 1 that became radiolabeled in the blood pool. Conclusions A new easily accessible and biocompatible copolymer, functionalized with TCO‐moieties for pretargeted
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imaging based on the tetrazine ligation has been developed. Current efforts include optimization of the approach by using a clearing or masking agent to minimize the level of residual polymer in the blood pool and obtain higher tumor‐to‐blood ratios. When the approach has reached its full potential, a pretargeted theranostic strategy would be of interest. ACKNOWLEDGMENTS This research has received funding from the H2020 project Click‐it under grant agreement no. 668532. R EF E RE N C E S 1. Rossin, R. et al. Angew. Chem. Int. Ed. 2010, 49 (19), 3375–3378. 2. Meimetis, L. G. et al. Angew. Chem. Int. Ed. 2014, 53, 7531‐7534.
Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-80 | Noninvasive imaging of CD38 using 64
Cu‐labeled F (ab)2 fragment from daratumumab in lymphoma models
Lei Kang1; Dawei Jiang2; Weijun Wei3; Dalong Ni2; Jonathan Engle4; Rongfu Wang1; Weibo Cai2
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1
Peking University First Hospital, China; 2 University of Wisconsin‐
Madison, USA; 3 Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China; 4 Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
Purpose CD38 has strong links with several kinds of lymphoma, especially for multiple myeloma (MM). CD38 has been considered as a biomarker for MM and in vivo evaluation of CD38 expression may provide useful information about lesion detection and prognosis of treatment in multiple myeloma (MM). In our previous study, immunoPET imaging with a 89Zr‐labeled CD38‐specific monoclonal antibody (daratumumab) was successfully used for differentiation of CD38 expression in murine lymphoma models. However, the long circulation and late uptake peak in the tumor of full antibody prevented its potential utility in the future clinical application. Therefore, we developed a 64Cu (t1/2 = 12.7 h) labeled F (ab′)2 fragment of daratumumab, smaller but with similar specificity, to visualize CD38 in the early phase. Methods Daratumumab‐F (ab′)2 fragments were produced using IdeS enzyme and purified with Protein A beads from Promega Corp. CD38 specific monoclonal antibody daratumumab and human non‐specific IgG F (ab
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′)2fragments were used as the control. F (ab′)2 fragments were evaluated using HPLC and gel electrophoresis. After conjugated with p‐SCN‐Bn‐NOTA (NOTA), the probes were radiolabeled with 64Cu. Fluorescein dye (Thermo Fisher) conjugated daratumumab‐F (ab′)2 was used to
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evaluate its cellular uptake. Ramos cells were implanted subcutaneously to build a lymphoma murine model overexpressing CD38. Small animal PET/CT imaging and biodistribution was performed within 48 h after injection of 64Cu labeled daratumumab‐F (ab′)2 or IgG‐F (ab′)2.
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Meanwhile, 64Cu labeled daratumumab was evaluated by imaging and biodistribution studies. Further, the histological analysis was performed to verify the CD38 expression in tumors. Results SDS‐PAGE verified the molecular weight of F (ab′)2 fragments was about 110 kDa, which proved the successful digestion. Fluorescein dye conjugated daratumumab‐F (ab′)2 showed high binding ability with Ramos cells. Via the conjugation with NOTA, F (ab′)2 fragments or intact antibody were labeled with 64Cu and its labeling yield was more than 90%. PET imaging revealed 64Cu labeled daratumumab‐F (ab′)2 had a rapid and high tumor uptake as early as 4 h post‐injection (8.2 ± 0.9 %ID/g) and reached the peak at 12 h (9.5 ± 0.7 %ID/g) (n = 4). It showed the highest tumor‐to‐background ratios at 12 h post‐injection (tumor‐to‐blood ratio = 4.6 ± 0.8; tumor‐to‐muscle ratio = 19.7 ± 3.5). In the comparison, 64Cu‐NOTA‐IgG‐ F (ab′)2 demonstrated a near‐background tumor uptake in Ramos model (2.0 ± 0.3 %ID/g at 12 h). Both of labeled F (ab′)2 fragments showed the highest uptake in kidneys. 64 Cu‐NOTA‐daratumumab had relatively high tumor uptake but long uptake retention in blood‐rich organs with low tumor‐to‐background ratios. Biodistribution studies showed that tumor uptake of 64Cu‐NOTA‐ daratumumab‐F (ab′)2 was 7.66 ± 0.54 while that of non‐ specific IgG was 0.80 ± 0.18 at 48 h, which verified the imaging results. Immunofluorescent staining displayed a strong CD38 expression in the tumor of Ramos. Conclusions In this study, 64Cu labeled daratumumab‐F (ab′)2 showed a rapid and high tumor uptake in CD38‐positive lymphoma, along with the low background. It provides a potential immunoPET imaging agent to visualize CD38 for the clinical application.
Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-81 | PET imaging of gastrin‐releasing peptide receptor with a novel bombesin analogue
68
Ga‐labeled
Joseph Lau; Etienne Rousseau; Zhengxing Zhang; Carlos Uribe; Hsiou‐Ting Kuo; Jutta Zeisler; Chengcheng Zhang; Daniel Kwon; Kuo‐Shyan Lin; Francois Benard BC Cancer Research Centre, Canada
Objectives Gastrin‐releasing peptide receptor (GRPR), a G protein‐ coupled receptor, is overexpressed in several solid
malignancies particularly in prostate cancer [1]. Thus, GRPR is a promising cancer imaging biomarker. For this study we synthesized [68Ga]Ga‐ProBOMB1 bearing a novel GRPR‐targeting sequence D‐Phe‐Gln‐Trp‐Ala‐Val‐ Gly‐His‐Leu‐ψ (CH2N)‐Pro‐NH2 (Figure 1A). We evaluated its pharmacokinetics and ability to image GRPR expression with positron emission tomography (PET), in comparison to the established clinical tracer [68Ga]Ga‐ NeoBOMB1 (Figure 1A) [2,3]. Methods ProBOMB1 (DOTA‐pABzA‐DIG‐D‐Phe‐Gln‐Trp‐Ala‐Val‐ Gly‐His‐Leu‐ψ (CH2N)‐Pro‐NH2) was synthesized using solid‐phase peptide synthesis approach. The polyaminocarboxylate chelator 1,4,7,10‐ tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) was coupled to the N‐terminus and separated from the GRPR‐targeting sequence by a p‐aminomethylaniline‐ diglycolic acid (pABzA‐DIG) linker. Binding affinity to GRPR was determined using a cell‐based competition assay, while agonist/antagonist property was determined with a calcium efflux assay. 68Ga labeling was conducted in HEPES buffer (1 M, pH 4.5) with microwave heating for 1 min, followed by HPLC purification. PET imaging and biodistribution studies were performed in male immunocompromised mice bearing GRPR‐expressing PC‐3 prostate cancer xenografts. Blocking experiments were performed with co‐injection of 100 μg of [D‐Phe6, Leu‐NHEt13,des‐Met14]Bombesin(6‐14). Dosimetry calculations were performed with OLINDA software based on the biodistribution data obtained from tumor‐bearing mice. Results ProBOMB1 and the non‐radioactive Ga‐ProBOMB1 were obtained in 1.1 and 67% yield, respectively. The Ki value of Ga‐ProBOMB1 for GRPR was 3.97 ± 0.76 nM. Ga‐ ProBOMB1 is an antagonist of GRPR as no significant calcium release was observed after incubating PC‐3 cells with up to 50 nM of Ga‐ProBOMB1. [68Ga]Ga‐ProBOMB1 was obtained in 48.2 ± 10.9% decay‐corrected radiochemical yield with 121 ± 46.9 GBq/μmol molar activity, and > 95% radiochemical purity. Imaging/biodistribution studies showed excretion of [68Ga]Ga‐ProBOMB1 was primarily through the renal pathway, while significantly higher hepatobiliary excretion of [68Ga]Ga‐NeoBOMB1 was observed (Figure 1B; scale of color bar: 0‐15 %IA/ mL). At 1 h post‐injection (p.i.), PC‐3 tumor xenografts were clearly delineated in PET images with better imaging contrast obtained by using [68Ga]Ga‐ProBOMB1. Based on biodistribution data at 1 h p.i., tumor uptake for [68Ga]Ga‐ProBOMB1 was 8.17 ± 2.57 percent injected activity per gram (%IA/g), and 9.83 ± 1.48 %IA/g for [68Ga]Ga‐NeoBOMB1. This corresponded to tumor‐to‐ blood and tumor‐to‐muscle uptake ratios of 20.6 ± 6.79
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and 106 ± 57.7 for [68Ga]Ga‐ProBOMB1, and 8.38 ± 0.78 and 39.0 ± 12.6 for [68Ga]Ga‐NeoBOMB1. Blockade with [D‐Phe6,Leu‐NHEt13,des‐Met14]Bombesin(6‐14) significantly reduced average uptake of [68Ga]Ga‐ProBOMB1 in tumors by 62%. The estimated absorbed radiation dose for an average adult human male was higher for [68Ga] Ga‐NeoBOMB1 than [68Ga]Ga‐ProBOMB1 across all organs except urinary bladder (0.0569 vs. 0.0659 mGy/ MBq). Notably, the pancreas is expected to receive vs 0.263 mGy/MBq for [68Ga]Ga‐NeoBOMB1 68 0.0144 mGy/MBq for [ Ga]Ga‐ProBOMB1. The kidney is expected to receive 0.0169 mGy/MBq for [68Ga]Ga‐ NeoBOMB1 vs 0.00432 mGy/MBq for [68Ga]Ga‐ ProBOMB1. Conclusions [68Ga]Ga‐ProBOMB1 is an excellent radiotracer for imaging GRPR expression with PET. [68Ga]Ga‐ProBOMB1
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achieved similar uptake as [68Ga]Ga‐NeoBOMB1 in tumor, but with enhanced tumor‐to‐background contrast and much lower whole‐body absorbed dose. ACKNOWLEDGMENTS This work was supported by the Canadian Institutes of Health Research (FDN‐148465) and the BC Leading Edge Endowment Fund. The authors thank Jinhe Pan, Navjit Hundal‐Jabal, Nadine Colpo, and Helen Merkens for technical assistance. RE FER EN CES 1. Mansi R, Minamimoto R, Macke H, et al. J Nucl Med 2016; 57 (Suppl. 3): 67S‐72S. 2. Dalm SU, Bakker IL, de Blois E, et al. J Nucl Med 2017; 58: 293‐299. 3. Nock BA, Kaloudi A, Lymperis E, et al. J Nucl Med 2017; 58: 75‐80.
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Radiolabeled Compounds ‐ Oncology (Imaging) Session 4 O-82 | Development of 18F‐fluoroglycosylated PSMA ligands with improved kidney clearance behavior Roman Potemkin; Brigitte Strauch; Manuel Geisthoff; Torsten Kuwert; Olaf Prante; Simone Maschauer Department of Nuclear Medicine, Molecular Imaging, and Radiochemistry, Friedrich‐Alexander University Erlangen‐Nürnberg (FAU), Germany
Objectives The aim of our study was the radiosyntheses, and in vitro and in vivo evaluation of new 18F‐fluoroglycosylated ligands for PET imaging of PSMA‐positive tumors. The alkyne‐functionalized PSMA ligand 1 is amenable to 18 F‐fluoroglycosylation via copper(I)‐catalyzed azide‐ alkyne cycloaddition (CuAAC, Scheme 1). The resulting 18 F‐glycoconjugates [18F]4 and [18F]5 are supposed to be alternative 18F‐radioligands for PET imaging of prostate cancer, in principle providing benefits when compared to the routinely used 68Ga‐PSMA‐11 analog, due to their longer half‐live together with an assumed improvement of the in vivo kidney clearance behavior of the glycosylated molecules. Methods Precursor 1 was synthesized as described by Chen et al. with slight modifications [1]. Our previously developed methodology based on CuAAC using 2‐deoxy‐2‐[18F] fluoroglucosyl azide ([18F]2) or 6‐deoxy‐6‐[18F] fluoroglucosyl azide ([18F]3) as prosthetic groups [2] was applied to the radiosyntheses of 18F‐fluoroglycosylated glutamate‐urea‐lysine based PSMA inhibitors 2‐[18F]
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FGlc‐PSMA ([18F]4) and 6‐[18F]FGlc‐PSMA ([18F]5) (Scheme 1). The PSMA binding affinity, expressed as IC50 value, was determined by competitive radioligand binding assays using 99mTc‐MIP‐1404 and PC‐3 PIP cells. The biodistribution and small animal PET studies were performed using PSMA‐positive PC‐3 PIP and PSMA‐negative PC‐3 tumor‐bearing nude mice. Results PSMA inhibitors [18F]4 and [18F]5 were obtained in high radiochemical yields of 19‐22% (non‐decay‐corrected, referred to [18F]fluoride) and in molar activities of 112‐ 136 GBq/μmol. PSMA ligands [18F]4 (IC50 = 234 ± 49 nM, n = 4) and [18F]5 (IC50 = 59 ± 12 nM, n = 4) showed moderate affinities to PSMA. In biodistribution studies at 60 min p.i. the specific uptake of [18F]4 and [18F]5 in PC‐3 PIP tumors was 13 ± 3 %ID/g and 6 ± 5 %ID/g (each n = 3), respectively. The PSMA‐negative PC‐3 tumors and all other tissues showed negligible low uptake values. Interestingly, [18F]4 showed remarkable retention in the kidneys from 30 to 60 min p.i. (74 to 72 %ID/g), such that the bladder did not accumulate radioactivity within the first 5 to 10 min after tracer injection. Contrary, [18F]5 revealed relatively low uptake of 7.5 %ID/g in kidneys at 30 min p.i. and was rapidly cleared (0.9 %ID/g at 120 min p.i.), leading to a high tumor‐to‐kidney ratio of 4:1 at 120 min p.i. Small animal PET studies demonstrated higher uptake of [18F]4 (5‐12 %ID/g, n = 4, p = 0.006 (paired t test)) and [18F]5 (3‐7 %ID/g, n = 4, p = 0.022 (paired t test)) in the tumor in comparison to 68 Ga‐PSMA‐11 (2‐5 %ID/g, n = 4), which could be blocked with PMPA by >99% (as shown for [18F]5). Conclusion Overall, the developed 18F‐fluoroconjugate radioligands, both the 6‐[18F]fluoroglucosyl derivative [18F]5 with its considerably reduced kidney uptake and the 2‐[18F] fluoroglucosyl derivative [18F]4 with its reduced bladder
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uptake at early time points after injection, demonstrated sufficient uptake in PSMA‐positive tumors in vivo, such that both candidates could be valuable for the translation into the clinic. R EF E RE N C E S 1. Chen Y, Lisok A, Chatterjee S, Wharram B, Pullambhatla M, Wang Y, Sgouros G, Mease RC, Pomper MG. [18F]Fluoroethyl triazole substituted PSMA inhibitor exhibiting rapid normal organ clearance. Bioconjug. Chem. 2016, 27: 1655‐1662. 2. Maschauer S, Haubner R, Kuwert T, Prante O. 18F‐Glyco‐RGD peptides for PET: efficient radiosynthesis by click chemistry and modulation of biodistribution by glycosylation. Molecular Pharmaceutics 2014, 11: 505–515.
Radiochemistry ‐
18
Methods Two‐step strategy (A): • STEP 1: Cyclotron produced [18F]fluoride ion in [18O] water was placed in a vial containing a solution of K‐2.2.2 and K2CO3 (2:1) in MeCN:H2O (10:1, v/v). Azeotropic drying with MeCN was performed four times. A solution of 2,2‐difluorovinyl tosylate and a proton source (e.g., IPA, NH4Cl) in DMSO was then added to the sealed vial and heated to 85 °C for a fixed time. An aliquot of the reaction mixture was then quenched and analyzed with radio‐HPLC. • STEP 2: Crude [18F]2,2,2‐trifluoroethyl tosylate was transferred to another reaction vial containing hydroxy precursor and K2CO3 in DMF. The sealed vial was heated to 130°C for a fixed time. An aliquot was then quenched and analyzed with radio‐HPLC.
F Session 2 One‐step strategy (B):
O-83 | Radiofluorination of a COX‐1 specific ligand based on two nucleophilic addition strategies Carlotta Taddei; Victor Pike
• A solution of 2,2‐difluorovinyl precursor and a proton source in DMSO was added to a sealed vial containing dried [18F]fluoride ion. The vial was heated to 130°C for a fixed time. A reaction aliquot was then quenched and analyzed with radio‐HPLC.
National Institute of Mental Health, USA
Objectives Cyclooxygenases, COX‐1 and COX‐2, are enzymes responsible for the synthesis of pro‐inflammatory prostaglandins and are being investigated as possible biomarkers of inflammation. COX‐1 may play an important role in neuroinflammation associated with neuropsychiatric disorders.1 Recently we reported the synthesis of a COX‐1‐specific PET radioligand [11C] PS13,2 and the selectivity of [11C]PS13 for quantifying COX‐1 in monkey brain.3 [11C]PS13 is now being evaluated in healthy human subjects. An 18F‐labeled version of PS13 could be valuable because the longer half‐life of fluorine‐18 (t1/2 = 109.8 min) versus that of carbon‐11 (t1/2 = 20.4 min) would enable transport over considerable distances to PET imaging centers without cyclotrons, and longer PET scans. PS13 contains a 1,1,1‐ trifluoroethoxy group as a possible site for 18F‐labeling. We conceived two strategies for 18F‐labeling of PS13 based on prior radiochemistry reports,4–6 namely, synthesis of [18F]2,2,2‐trifluoroethyl tosylate for reaction with a hydroxy precursor (two‐step process) (Scheme 1, A) and reaction with a 2,2‐difluorovinyl precursor with [18F]fluoride ion (one‐step process) (Scheme 1, B). The goal of this work was to evaluate the applicability of each strategy for the nucleophilic addition of [18F]fluoride ion to the synthesis of [18F]PS13.
Radioactive product identities were confirmed with mass spectrometry of associated carrier and co‐elution with reference compound on reversed phase HPLC. Results Two‐step strategy (A): • STEP 1: [18F]2,2,2‐trifluoroethyl tosylate was obtained in up to 70% radiochemical purity (RCP), up to 64% yield within 1 min, and with a molar activity (Am) up to 23.0 GBq/μmol. • STEP 2: [18F]PS13 was obtained in up to 32% RCP, up to 31% yield within 20 min from the start of synthesis, and with an Am up to 6.4 GBq/μmol. One‐step strategy (B): • [18F]PS13 was achieved in up to 4% RCP, up to 3% yield within 20 min from the start of synthesis, and with an Am up to 20.3 GBq/μmol. Conclusions [18F]PS13 was prepared through two nucleophilic 18F‐ fluorination strategies in acceptable yield (≤31%) and Am (≤20.3 GBq/μmol) within 20 min from the start of synthesis. The two‐step strategy gave [18F]PS13 in higher yield than the one‐step strategy, whereas a higher Amvalue was obtained with the one‐step strategy. For both methodologies, increased nucleophilic addition time
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decreased Am, presumably due to increased extent of an 18 19 F/ F isotopic exchange[4]. ACKNOWLEDGEMENTS This work was supported by the Intramural Research Program of the National Institutes of Health (NIMH; ZIA MH002793). The authors would like to acknowledge Dr. Shuiyu Lu and Ms. Cheryl Morse for their technical support during this work.
Radiochemistry ‐
R EF E RE N C E S
1
1. Bosetti F. et al., Biochimie 2011, 93, 46.
Radiopharmaceutical and Chemical Biology, Institute of
2. Singh P. et al., ACS Chem Neurosci. 2018, https://doi.org/ 10.1021/acschemneuro.8b00102.
Rossendorf, Germany
3. Shrestha S. et al., ACS Chem Neurosci. 2018, https://doi.org/ 10.1021/acschemneuro.8b00103. 4. Riss P.J. et al., Chem Commun. 2011, 47, 11873. 5. Riss P.J. et al., Org Biomol Chem. 2012, 10, 6980. 6. Fawaz M.V. et al., ACS Chem Neurosci. 2014, 5, 718.
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F Session 2
O-84 | Kit‐like 18F‐labeling using triazole‐linked conjugates for [18F]aluminum monofluoride complexation Martin Walther1; Christin Neuber1; Ralf Bergmann1; Jens Pietzsch2; Hans‐Jurgen Pietzsch1 Helmholtz‐Zentrum Dresden‐Rossendorf, Germany; 2 Department
Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum Dresden‐
Objectives For about 10 years, numerous ligands have been developed and tested for their suitability for 18F‐labeling in the form of [18F]aluminum monofluoride. Initially,
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the well‐known macrocyclic ligands NOTA and NODA1,2 with high temperature reactions were used. Under current approaches, open chain ligands, derived from ethylene diamine, provide a much faster complex formation at lower temperatures (95%. 3‐Deoxy‐3‐[18F]‐fluororibose‐5‐ methylenephosphonic acid was synthesized in 9% radiochemical yield (n = 3) with a radiochemical purity of >95%. Cold standards were synthesized using analogous chemistry using 19F reagents. The cold standards were used for kinetic measurements against ribose‐phosphate diphosphokinase. 3‐Deoxy‐3‐[18F]‐fluororibose was not a substrate as expected. 3‐Deoxy‐3‐[18F]‐fluororibose‐5‐ methylenephosphonic acid was determined to have a catalytic efficiency (kcat/Km) of 39 mM−1 s−1. The catalytic efficiency of the natural substrate, ribose‐5‐phosphate was determined to be 42 mM−1 s−1. Conclusions and 3‐deoxy‐3‐[18F]‐ 3‐Deoxy‐3‐[18F]‐fluororibose fluororibose‐5‐methylenephosphonic acid have been successfully synthesized and evaluated as substrates for ribose‐phosphate diphosphokinase. The preliminary results are encouraging that we will be able to develop imaging agents for this biomarker. In vitro and in vivo experiments are currently underway. ACKNOWLEDGMENTS This work was achieved through a DOD Prostate Cancer Research Program Postdoctoral Fellowship W81XWH‐17‐ 1‐0198.
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R EF E RE N C E S 1. (a) Visentin LP, Hasnain S, Gallin W. FEBS Lett.1977, 79 (2): 258–63. (b) Li S, Lu Y, Peng B, Ding J. Biochem. J. 2007,401 (1): 39–47. (c) Tang W, Li X, Zhu Z, Tong S, Li X, Zhang X, Teng M, Niu L. Acta Crystallographica Section F.2006, 62 (Pt 5): 432–4. 2. Cunningham JT, Moreno MV, Lodi A, Monen SM, Ruggero D. Cell. 2014, 158 (3), 689‐93. 3. Evdokimov NM, Clark PM, Flores G, Chai T, Faull KM, Phelps ME, Witte ON, Jung ME. J. Med. Chem.2015, 58, 14, 5538‐5547.
Radiochemistry ‐
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F Session 2
O-87 | Radiofluorination of non‐activated aromatic prosthetic groups for efficient synthesis of fluorine‐18 labelled ghrelin(1‐8) analogues Marina Lazarakos1; Michael Kovacs2; Leonard Luyt1 1
University of Western Ontario, Canada; 2 The Lawson Health Research
Institute, Canada
Objectives The growth hormone secretagogue receptor 1a (GHSR‐1a) is a protein differentially expressed in a number of cancer types compared to healthy tissues, and thus is a receptor target for cancer imaging. The endogenous ligand for the GHSR‐1a is ghrelin, a 28 amino acid peptide acylated with an octanoyl side chain on the serine residue in the third position. Substantial effort has been made to develop fluorine‐18 labelled analogues of ghrelin for PET imaging resulting in a short 8 amino acid peptide bearing a 6‐ fluoro‐2‐naphthoyl (6‐FN) group in place of the octanoyl side chain. The peptide [Inp1,Dpr3(6‐FN),1Nal4,Thr8] ghrelin(1‐8) amide (1) showed sub‐nanomolar receptor affinity (IC50 = 0.11 nM) toward the GHSR‐1a making it the highest affinity ghrelin analogue reported to date.1 Fluorine‐18 was incorporated into this peptide through a [18F]6‐fluoro‐2‐pentafluorophenyl naphthoate prosthetic group, which was radiolabelled using conventional nucleophilic aromatic substitution techniques. However, the non‐activated nature of this prosthetic group resulted in low isolated radiochemical yields of only 3.1% decay corrected for [18F]1 creating a need for an improved radiofluorination method.1 Recently, the use of spirocyclic iodonium (III) ylide precursors have been applied toward the synthesis of non‐activated [18F]‐labelled arenes.2 Therefore, we sought to employ this technique to improve 18 F‐labelling of 1. Since aromatic groups appear to be of value for incorporating fluorine‐18 while maintaining binding affinity, we also propose to expand this chemical
space by synthesizing, evaluating, and radiolabelling the ghrelin(1‐8) peptide with other non‐activated fluorine‐ containing aromatic groups in position 3. Methods A 4′‐fluoro‐4‐biphenylcarboxyl (4′‐FBC) group was synthesized and conjugated to the ghrelin(1‐8) peptide as the side chain in position 3. The novel [Inp1,Dpr3(4′‐ FBC),1Nal4,Thr8]ghrelin(1‐8) amide (2) peptide was evaluated for binding toward the GHSR‐1a through a radioligand displacement binding assay in HEK293 GHSR+ cells. A spiroadamantyl‐1,3‐dioxane‐4,6‐dione (SPIAd) auxiliary was synthesized and conjugated to methyl 6‐iodo‐2‐naphthoate and methyl 4′‐iodo‐4‐ biphenylcarboxylate according to literature procedures to prepare the precursors for fluorine‐18 labelling of 1 and 2.2 Both 18F‐labelled prosthetic groups were prepared as pentafluorophenyl esters in 3 steps and conjugated to the peptide precursor, [Inp1,Dpr3,1Nal4,Thr8]ghrelin(1‐8) amide. Results Peptide 2 was found to possess a binding affinity of IC50 = 1.7 nM, which is comparable to that of human ghrelin (IC50 = 3.1 nM). Fluorine‐18 labelling and preparation of the [18F]6‐FN (56 ± 6% isolated RCY, d.c., RCP > 98%, n = 3) and the [18F]4’‐FBC prosthetic groups (31 ± 3% isolated RCY, d.c., RCP > 98%, n = 3) for peptide conjugations was accomplished from the corresponding spirocyclic iodonium (III) ylide precursors. This resulted in an improved overall radiochemical yield for [18F]1 (25 ± 2% isolated RCY, d.c., n = 3) and successful radiolabelling of the novel [18F]2 (17 ± 3% isolated RCY, d.c., n = 3). Conclusions We have demonstrated the ability for fluorine‐containing non‐activated aromatic compounds to be incorporated in place of the natural octanoyl side chain in ghrelin analogues. These groups not only play a critical role in binding toward the receptor but also as the fluorine source for 18 F‐PET imaging. Peptide [18F]2 was prepared in a moderate radiochemical yield of 17% d.c., using an iodonium (III) ylide‐based radiolabelling technique, while the radiochemical yield of previously reported [18F]1 was improved 8‐fold using the same method. The high binding affinity of 1 and improved radiofluorination yields make this peptide an attractive prospect for pre‐clinical imaging of cancer models and other diseases associated with high expression of the GHSR‐1a. ACKNOWLEDGEMENTS We thank the Lawson Cyclotron and PET Radiochemistry facility at St. Joseph's Hospital in London, ON, for their generous donation of [18F]F− used for this work. Funding sources: Canadian Institutes of Health Research (CIHR); Natural Sciences and Engineering Research
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Council (NSERC); Molecular Imaging Collaborative Program, University of Western Ontario. R EF E RE N C E S 1. Charron, C.L., Hou, J., McFarland, M.S., Dhanvantari, S., Kovacs, M.S., Luyt, L.G. J. Med. Chem. 2017, 60, 7256. 2. Rotstein, B.H., Wang, L., Liu, R.Y., Patteson, J., Kwan, E., Vasdev, N., Liang, S.H. Chem. Sci. 2016, 7, 4407.
Radiochemistry ‐
18
F Session 2
O-88 | Development of pyridine‐based precursors for direct labeling of biomolecules Mylène Richard1; Mélanie Roche2; Simon Specklin1; Bertrand Kuhnast1 1
Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS,
Université Paris Sud, Université Paris‐Saclay, Service Hospitalier Frédéric Joliot, France; 2 Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris‐Sud, Université Paris‐Saclay, Service Hospitalier Frédéric Joliot, Orsay, France
Objectives Fluorine‐18 labeled biomolecules are increasingly employed in molecular imaging but their radiolabeling remains a challenge. Indeed, the drastic conditions (high temperature in particular) required for radiofluorination
are not compatible with the complexity and fragility of these compounds. To deal with these issues, most strategies rely on two‐steps methods involving the preparation of a 18F‐labeled prosthetic group subsequently conjugated to the biomolecule in biocompatible conditions. Based on recent work on pyridines fluorination,1 we aim to develop an activated pyridine tag enabling a direct one‐step radiofluorination of biomolecules in mild conditions. Methods We synthesized several pyridine moieties bearing different electron‐withdrawing groups (nitrile, ester and amide) and studied their radiofluorination kinetics to select the best activating group. The syntheses of the precursors and cold references were carried out from commercially available pyridones via an original aromatic substitution of triflate intermediates by tertiary amines. Radiofluorinations were performed in DMSO with K[18F]F/K222 complex at 25°C and 40°C in triplicates, and the reaction conversions were monitored by radioTLC and controlled by analytical HPLC. The best electron‐withdrawing group was then selected for the synthesis of a pyridine tag containing an activated ester as reactive handle for pre‐conjugation to a biomolecule. This tag was then conjugated to RGD, PSMA and octreotide and utilized for direct radiofluorination of these model peptides. Results Sixteen trialkyammonium precursors were synthesized in two or three steps starting from pyridones in 47 to 94%
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overall yields. Activated precursors bearing an ester or a nitrile group led to the expected 18F‐pyridines with a conversion >90% in less than 15 minutes at 40°C, whereas the less activated amide precursors exhibited a slightly lower conversion of 70% within the same reaction time. Besides, it is noteworthy that labelling for 15 minutes at room temperature was sufficient to get a radiofluorination yield >70% for most of the precursors. Stability studies were performed by adding PBS buffer to the reaction mixture and HPLC analysis showed no degradation of the radiofluorinated products after 30 minutes incubation. Conclusions The syntheses and radiolabeling kinetic studies of 16 activated pyridines were carried out and enabled the selec-
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tion of an optimized pyridine scaffold for aromatic radiofluorination in mild conditions. Conjugation of this activated pyridine tag to model peptides is in progress and direct radiofluorination of the conjugates will be examined in the near future. ACKNOWLEDGMENTS Mylène Richard is funded by CEA‐DRF‐Impulsion “IRIP” program.
RE FER EN CE 1. Olberg, D.E., Arukwe, J. M., Grace, D., Hjelstuen, O. K., Solbakken, M., Kindberg, G. M. and Cuthbertson, A. J. Med. Chem. 2010, 53 (4), 1732‐1740
Contents Poster
S124: Poster
23rd International Symposium on Radiopharmaceutical Sciences
POSTER CATEGORY: RADIOCHEMISTRY - 18F P-001
Synthesis and initial in vitro characterization of [18F]fluoroalkyl derivatives of GSK1482160 as new candidate P2X7R radioligands M. Gao, M. Wang, B. Glick-Wilson, J. Meyer, J. Peters, P. Territo, M. Green, G. Hutchins, H. Zarrinmayeh, Q. Zheng Indiana University School of Medicine, United States
S 154
P-002
Radiosynthesis of a novel 18F-labeled triazole PET tracer for imaging GluN2B in the brain H. Fu1, X. Zhang2, Z. Chen1, Q. Yu1, Y. Shao3, S. Sun4, H. Wey1, L. Josephson1, Z. Li5, S. Traynelis6, S. Liang1 1MGH/Harvard, United States; 2MGH/Harvard, China; 3University of Oklahoma, United States; 4College of Nuclear Technology and Chemistry and Biology, Hubei University of Science and Technology, China; 5Center for Molecular Imaging and Translational Medicine, Xiamen University, China; 6Department of Pharmacology, Emory University School of Medicine, United States
S 155
P-003
Synthesis and evaluation of trialkyammonium salts as 18F labeling precursors for AZD4694 (NAV4694) H. Xiong, K. Fan, A. Hoye, C. Horchler, N. A. Lim, G. Attardo Avid Radiopharmaceuticals, Inc., a wholly-owned subsidiary of Eli Lilly and Company, United States
S 157
P-004
Simplified synthesis of [18F]NS12137 via copper-mediated 18F-fluorination S. Lahdenpohja, N. Rajala, A. Kirjavainen Turku PET Centre, University of Turku, Finland
S 158
P-005
Development, biological evaluation and PET application of [18F]fluoro-glyco”RGD” T. Vucko, C. Collet, G. Karcher, N. P. Moïse, S. Lamande-Langle University de Lorraine, France
S 158
P-006
Radiosynthesis of [18F]FEDAC with the hydrous 18F-fluorination using Kryptofix 222 and potassium carbonate. K. Kawamura1, K. Kumata2, W. Mori3, M. Fujinaga4, Y. Kurihara5, M. Ogawa5, N. Nengaki5, M. Zhang2 1National Institute of Radiological Sciences, National Institute for Quantum and Radiological Science and Technology, Japan; 2Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 4National Institute of Radiological Sciences, Japan; 5SHI Accelerator Service, Japan
S 159
P-007
Synthesis and application of [18F]fluorobenziodoxole M. C. Gonzalez1, P. Nordeman2, A. B. Gomez1, D. Meyer1, G. Antoni2, M. Schou3, K. Szabo1 1Stockholm University, Sweden; 2Uppsala University Hospital, Sweden; 3AstraZeneca PET Centre at Karolinska Institutet, Sweden
S 160
P-008
Synthesis of 6-[F-18]Fluoropyridine-3-carbaldehyde-O-[4-(2,5-dioxo-2,5-dihydropyrrol-1-yl)butyl and pentyl]oximes, novel thiol reactive bifunctional agents for peptide labeling M. Akula1, D. Blevins2, G. Kabalka3, D. Osborne4 1University of Tennessee Medcial center, United States; 2The University of Tennessee, GSM, United States; 3University of Tennessee Medical Center, United States; 4The university of Tennessee Medical Center, United States
S 161
P-009
Synthesis and biological investigation of a novel fluorine-18 labeled benzoimidazotriazine: A Potential radioligand for in vivo phosphodiesterase 2A (PDE2A) PET imaging R. Ritawidya, R. Teodoro1, B. Wenzel2, M. Kranz, M. Toussaint2, S. Dukic-Stefanovic, W. Deuther-Conrad, M. Scheunemann2, P. Brust2 1Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden Rossendorf, Germany; 2Helmholtz-Zentrum Dresden-Rossendorf, Germany
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P-010
A simple SPE purification method for 18F-radiolabeling: Proof-of-concept study in stilbene amyloid-β ligands with a neopentyl labeling group T. Tago1, J. Toyohara1, R. Fujimaki2, K. Hirano3, K. Iwai3, K. Ishibashi1, H. Tanaka2 1Tokyo Metropolitan Institute of Gerontology, Japan; 2Tokyo Institute of Technology, Japan; 3NMP Business Support Co., Ltd., Japan
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P-011
Design of a new 18F-prosthetic reagent for the “thiol-ene”-Dha-based conjugation with proteins M. Richard, S. Specklin, F. Hinnen, B. Kuhnast Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France
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P-012
Cobalt-catalyzed C–F bond borylation of aryl fluorides for PET applications E. Lee Pohang University of Science and Technology
S 166
P-013
18F-fluorination
of BaGdF5 nanoparticles for multimodal imaging and PET/CT biodistribution in mouse. L. Fernandez-Maza1, A. Corral2, A. Becerro3, D. Gonzalez4, A. Parrado2, M. Balcerzyk5, M. Ocana6 1Universidad de Sevilla, CSIC, Junta de Andalucía, Spain; 2Universidad de Sevilla, CSIC, Junta de Andalucia, Spain; 3CSIC, Universidad de Sevilla, Spain; 4CSIC,Universidad de Sevilla, Spain; 5Universidad de Seville, CSIC, Junta de Andalucia, Spain; 6CSIC, Junta de Andalucia, Spain
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P-014
4-Nitrophenyl activated esters are superior synthons for indirect radiolabelling of biomolecules; A direct radiofluorination tolerance and acylation kinetics study M. Haskali1, A. Farnsworth2, R. Hicks3, P. Roselt1, C. Hutton2 1Peter MacCallum Cancer Centre, Australia; 2School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Australia; 3The Peter MacCallum Cancer Centre, Australia
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J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S125
P-015
Automated radiosynthesis of a PDE10A PET radiotracer: [18F]TZ20A - two-pot, two-step, and two-HPLC purification on one module J. Fan1, N. Yasui, Z. Luo2, Z. Tu3 1UAB, United States; 2Washington University School of Medicine in Saint Louis, United States; 3Department of Rdiology, Washington University School of Medicine in Saint Louis, United States
S 168
P-016
Radiosynthesis of [18F]Fluoroaminoesters by deoxyradiofluorination of b-hydroxy-a-aminoesters under mild conditions M. Morlot, F. Gourand1, C. Perrio2 1CYCERON ISTCT/LDM-TEP, France; 2Cyceron, France
S 170
P-017
An improved synthesis of 4-(4-[F-18]fluorophenyl)piracetam, a PET agent for Parkinson’s disease D. Blevins1, M. Akula2, G. Kabalka3, D. Osborne4 1The University of Tennessee, GSM, United States; 2University of Tennessee Medcial Center, United States; 3University of Tennessee Medical Center, United States; 4The university of Tennessee Medical Center, United States
S 171
P-018
A novel [18F]fluoride relay reagent for radiofluorination reactions B. Zhang1, B. Fraser2, M. Klenner3, Z. Chen4, S. Liang4, M. Massi5, A. Robinson6, G. Pascali3 1Australia’s Nuclear Science and Technology Organisation (ANSTO), Australia; 2The Australian Nuclear Science and Technology Organisation, Australia; 3ANSTO, Australia; 4MGH/Harvard, United States; 5Curtin University, Australia; 6Monash University, Australia
S 172
P-019
An improved method for preparing [18F]AV-45 using solid-phase extraction purification L. Zhang1, Y. Zhang1, F. Liu1, X. Yao1, Z. Zha2, Y. Liu3, J. Qiao1, L. Zhu4, H. Kung2 1College of Chemistry, Beijing Normal University, China; 2University of Pennsylvania, United States; 3Beijing Institute of Brain Disorders, Capital Medical University, China; 4Beijing Normal University, China
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P-020
18F
labeled pyrrolopyrimidine derivatives targeting LRRK2 for evaluation of Parkinson’s disease X. Chen, Z. Mou1, Y. Zhang1, H. Yang1, Z. Li2, F. Xie3 1Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, China; 2Xiamen University, Center for Molecular Imaging and Translational Medicine, China; 3PET Center, Huashan Hospital, Fudan University, China
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P-021
Automated radiosynthesis of 2-[18F]BTSO2CF2H in a GE FASTLab synthesizer A. Lemos1, L. Trump2, B. Lallemand3, P. Pasau3, J. Mercier3, C. Genicot3, C. Lemaire4, A. Luxen5 1University of Liège, Belgium; 2Global Chemistry, UCB New medicines, UCB Biopharma SPRL, Belgium; 3Global Chemistry, UCB NewMedicines, UCB Biopharma SPRL, Belgium; 4GIGA Cyclotron Research Centre In Vivo Imaging, University of Liège, Belgium; 5Universite De Liege, Belgium
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P-022
Rapid and chemoselective ligation of hydroxylamine-functionalized biomolecules with [18F]6-fluoronicotinoyltrifluoroborate at room temperature H. Ahmed1, A. Chiotellis2, C. White1, T. Betzel1, S. D. Ros1, R. Schibli1, J. Bode1, S. Ametamey3 1ETH Zurich, Switzerland; 2NCSR Demokritos, Greece; 3Radiopharmacy, ETH Zurich, Switzerland
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P-023
BF3-Gln-C2 as a stable 18F-labeled glutamine derivative for imaging tumor J. Chen, C. Li, J. Li, Z. Liu Peking University, China
S 177
P-024
One-step synthesis of [18F]MC225 intended for GMP compliant productions L. G. Varela, K. Attia, I. Antunes1, C. Kwizera, A. Niezink, R. Zijlma, T. Visser, R. Dierckx1, P. Elsinga2, G. Luurtsema2 1UMCG, Netherlands; 2University Medical Center Groningen, Netherlands
S 178
P-025
Development of scandium-catalyzed N-[18F]fluoroalkylation of aryl and heteroaryl amines with [18F]epifluorohydrin M. Fujinaga1, T. Ohkubo2, K. Kumata3, N. Nengaki2, M. Zhang3 1Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2SHI Accelerator Service, Japan; 3Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
S 180
P-026
Ruthenium-mediated 18F-fluorination of phenols at Turku PET Centre N. Rajala, S. Lahdenpohja, A. Kirjavainen Turku PET Centre, University of Turku, Finland
S 181
P-027
Development of a new 18F-labeled radioligand for imaging sigma2 receptors by positron emission tomography F. Ludwig1, S. Fischer2, R. Moldovan3, W. Deuther-Conrad, M. Kranz, D. Schepmann4, H. Jia5, B. Wünsch, P. Brust6 1Department of Neuroradiopharmaceuticals, Research Site Leipzig, Helmholtz-Zentrum Dresden-Rossendorf, Institute for Radiopharmaceutical Cancer Research, Germany; 2HZDR, FS Leipzig, Germany; 3Helmholtz-Zentrum Dresden Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 4Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Germany; 5Beijing Normal University, China; 6Helmholtz-Zentrum Dresden-Rossendorf, Germany
S 181
P-028
Investigation of [18F]FESCH for PET imaging of the adenosine A2A receptor in a rotenone-based mouse model of Parkinson’s disease and development of a two-step one-pot radiolabeling strategy S. Schroeder, T. H. Lai1, M. Kranz, M. Toussaint1, Q. Shang2, S. Dukic-Stefanovic, F. Pan-Montojo3, P. Brust1 1Helmholtz-Zentrum Dresden-Rossendorf, Germany; 2Ludwig-Maximilians-Universität (LMU) Munich, University Hospital Großhadern, Neurological Clinic, Department of Neurology, Munich (Germany) AND Technische Universität Dresden (TUD), University Hospital Carl Gustav Carus, Clinic of Neurology, Dresden, Germany; 3Ludwig-Maximilians-Universität (LMU) Munich, University Hospital Großhadern, Neurological Clinic, Department of Neurology, Munich, Germany
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S 183
S126: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-029
Ligand effect in the radiofluorination of aryl pinacol boronates catalyzed by copper (II) triflate complexes D. Antuganov1, V. Timofeev1, K. Timofeeva1, M. Zykov1, V. Orlovskaya2, R. Krasikova3 1Almazov National Medical Research Centre, Russian Federation; 2N.P. Bechtereva Institute of Human Brain, Russian Academy of Science, Russian Federation; 3N.P.Bechtereva Institute of Human Brain Russian Academy of Sciences, Russian Federation
S 183
P-030
Elution efficiency of [18F]fluoride from OASIS WAX cartridge using DMA solution of 4-dimethylaminopyridinium trifluoromethanesulfonate D. Antuganov1, V. Timofeev1, K. Timofeeva1, V. Orlovskaya2, R. Krasikova3 1Almazov National Medical Research Centre, Russian Federation; 2N.P. Bechtereva Institute of Human Brain, Russian Academy of Science, Russian Federation; 3N.P. Bechtereva Institute of Human Brain Russian Academy of Sciences, Russian Federation
S 185
P-031
Synthesis of 18F-labelled fragmented antibody [18F]Fab O. Eskola1, C. Yim2, T. Johnson3, J. Bergman4, O. Solin5 1Turku PET Centre, University of Turku, Finland; 2Turku PET Centre, Finland; 3UCB Pharma, United Kingdom; 4Turku PET Center, Finland; 5University of Turku, Finland
S 186
P-032
Site-specific conjugation and fluorine-18 radiolabeling of non-immunoglobulin-based scaffold proteins M. Vandamme1, F. Cleeren2, G. Bormans1 1KU Leuven, Belgium; 2Radiopharmaceutical Research, Department of Pharmacy and Pharmacology, University of Leuven, Belgium
S 187
P-033
Development of new fluorination methods for fluorine-18 labelling of aromatic compounds R. Pelletier, B. Kuhnast, S. Specklin Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France
S 188
P-034
Improved and simpler radiosynthesis of [18F]ADAM, a radioligand for PET imaging of serotonin transporters S. M. Sephton, X. Zhou, S. Thompson, F. Aigbirhio University of Cambridge, United Kingdom
S 189
P-035
New strategy for infection PET imaging by fluorine-18 labeling of a bacterial azide-containing LPS S. Specklin1, A. Baron2, M. Badet-Denisot2, B. Vauzeilles2, B. Kuhnast1 1Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 2ICSN, UPR-CNRS 2301, 91198, Gif-sur-Yvette Cedex, Université Paris-Saclay, France
S 190
P-036
Novel Pyridinyl Quarternary Ammonium Salts as Precursors of Radiofluorination D. Blevins1, M. Akula2, G. Kabalka2, D. Osborne2 1The University of Tennessee, GSM, United States; 2University of Tennessee Medcial Center, United States
S 191
P-037
Synthesis and in-vitro evaluation of novel PET probes 18F-CNPI and 18F-CNBI for glycogen synthase kinase-3 imaging M. Pandey1, H. Berg2, N. Nelson2, A. Bansal2, A. Walsh2, L. Peyton2, T. DeGrado3, V. Lowe2, M. Frye2, J. Port2 1Department of Radiology, Mayo Clinic, United States; 2Mayo Clinic Rochester, United States; 3Mayo Clinic, United States
S 192
P-038
Radiofluorination of higher-valent aryliodines: A comparative investigation of [18F]fluoroarenes produced from hypervalent compounds a different oxidation states Y. Kwon, J. Son, Y. H. Ryu1, J. Chun2 1Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Republic of Korea; 2Yonsei University College of Medicine, Republic of Korea
S 193
P-039
One-step synthesis of [18F]fluoro-4-(vinylsulfonyl)benzene (FVSB): A thiol reactive synthon for selective radiofluorination of peptides and proteins J. Murphy, G. Ma University of California Los Angeles, United States
S 194
P-040
Radiofluorination of p-aminobenzoic acid for bacterial infection imaging with PET J. Fang1, X. Lin, H. Yang, J. Li, R. Zhuang2, X. Zhang3 1State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics & Center for Molecular Imaging and Translational Medicine, China; 2State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, China; 3Xiamen University, China
S 195
P-041
Aromatic [18F]fluorination of [18F]BS224 and its bioevaluation in animal models of neuroinflammation and stroke S. H. Lee1, I. H. Song2, S. Y. Lee1, B. S. Moon3, H. S. Park2, S. E. Kim3, B. C. Lee 1Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Republic of Korea; 2Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea; 3Seoul National University Bundang Hospital, Korea, Republic of, 4Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea
S 196
P-042
BTC5A (Bis-Triethylene glycol-functionalized Crown-5-calix[4]Arene) analogs: Phase-transfer catalysts for Aromatic [18F]fluorination W. Lee1, S. M. Kang, D. W. Kim2, B. C. Lee3, S. E. Kim4 1Department of Transdisciplinary studies, Graduate School of Convergence Science and Technology, Seoul National University, Republic of Korea; 2Inha University, Republic of Korea; 3Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea; 4Seoul National University Bundang Hospital, Republic of Korea
S 197
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S127
P-043
Rhenium complexation-dissociation strategy for fluorine-18 labelling of bidentate PET ligands M. Klenner1, G. Pascali1, B. Zhang2, M. Massi3, B. Fraser4 1ANSTO, Australia; 2Australia’s Nuclear Science and Technology Organisation (ANSTO), Australia; 3Curtin University, Australia; 4The Australian Nuclear Science and Technology Organisation, Australia
S 198
P-044
Drying free 18F labeling of phosphate analogues with high stability in vivo H. Yang, Z. Li Center for Molecular Imaging and Translational Medicine, Xiamen University, China
S 199
P-045
Studies on F2-free UV photon-mediated production of [18F]F2 A. Krzyczmonik1, M. Haaparanta-Solin1, O. Solin1,2 1University of Turku, Finland; 2Åbo Akademi University, Finland
S 200
P-046
One step synthesis of N-succidimidyl-4-[18F]-fluorobenzoate ([18F]SFB) I. Petersen1, A. Kjær2, M. Herth3, J. Madsen4 1Department of Clinical Physiology, Nuclear Medicine and PET, University Hospital Copenhagen, Denmark; 2Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 3Univesity of Copenhagen, Sweden; 4Copenhagen University Hospital, Denmark
S 201
P-047
Bis-triethylene glycolic crown-5-calix[4]arene as an efficient phase-transfer catalyst for nucleophilic radiofluorination with K18F S. M. Kang, H. Kim, K. C. Lee1, C. H. Park, D. W. Kim2 1KIRAMS, Republic of Korea; 2Inha University, Republic of Korea
S 202
P-048
Organophosphine fluoride acceptors based one-step 18F-labeling in aqueous media H. Hong, R. Zhuang1, H. Liu, J. Li, H. Yang, X. Zhang2, Z. Li3 1State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, China; 2Xiamen University, China; 3Center for Molecular Imaging and Translational Medicine, Xiamen University, China
S 202
P-049
Discovery of new ligand for copper mediated [18F]trifluoromethylation from aryl iodides J. Y. Choi1, S. Das, D. Y. Bae2, E. Lee2, B. C. Lee3, S. E. Kim4 1Seoul National University, Republic of Korea; 2POSTECH, Republic of Korea; 3Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea; 4Seoul National University Bundang Hospital, Republic of Korea
S 204
P-050
Convenient access to 18F-labeled amines through the Staudinger reduction V. Shalgunov1, J. Steen1, C. Denk2, H. Mikula2, A. Kjær3, J. Kristensen4, M. Herth5 1Department of Drug Design and Pharmacology, University of Copenhagen, Denmark; 2Institute of Applied Synthetic Chemistry, Technische Universität Wien (TU Wien), Austria; 3Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 4Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 5 Univesity of Copenhagen, Sweden
S 205
P-051
Late stage 18F-difluoromethylation via a flow photoredox reaction to N-heteroaromatics. L. Trump1, A. Lemos2, B. Lallemand3, J. Mercier3, P. Pasau3, C. Lemaire4, A. Luxen5, C. Genicot3 1Global Chemistry,UCB New medicines, UCB Biopharma SPRL, Belgium; 2University of Liège, Belgium; 3Global Chemistry, UCB NewMedicines, UCB Biopharma SPRL, Belgium; 4Cyclotron Research Center, Universite De Liege, Belgium; 5Universite De Liege, Belgium
S 206
P-052
Preparation of 18F-labeled aromatic amino acids by copper-mediated radiofluorination J. Ermert1, B. Neumaier2, B. Zlatopolskiy3, D. Modemann4 1Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry, Germany; 2Forschungszentrum Jülich GmbH, Germany; 3Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany; 4Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry, Jülich, Germany
S 206
P-053
The use of methanolic solution of tetrabutylammonium tosylate in the preparation of reactive [18F]fluoride and aliphatic radiofluorinations V. Orlovskaya1, O. Fedorova2, D. Antuganov3, R. Krasikova2 1N.P. Bechtereva Institute of Human Brain, Russian Academy of Science, Russian Federation; 2N.P.Bechtereva Institute of Human Brain, Russian Academy of Sciences, Russian Federation; 3Almazov National Medical Research Centre, Russian Federation
S 207
P-054
18F-Fluorination
on natural monophosphate Z. Mou, H. Yang, C. Wang, Z. Li Center for Molecular Imaging and Translational Medicine, Xiamen University, China
S 208
P-055
Explorations towards the chemical scope of [18F]triflyl fluoride, a new gaseous [18F]fluoride source L. Haveman1, A. Pees2, D. Vugts2, A. Windhorst1 1VU University Medical Center, Netherlands; 2Amsterdam UMC, VU University, Netherlands
S 209
P-056
Radiosynthesis of 18F-Crizotinib, a potential radiotracer for PET imaging of the P-glycoprotein transport function S 210 at the blood-brain barrier M. Sardana1, F. Caillé2, M. Kondrashov3, M. Schou4, G. Wrigley5, N. Tournier6, C. Elmore1, B. Kuhnast2 1Early Chemical Development, Pharmaceutical Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden; 2Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 3Karolinska Institute, Sweden; 4AstraZeneca PET Centre at Karolinska Institutet, Sweden; 5Medicinal Chemistry, Oncology, IMED Biotech Unit, AstraZeneca, Cambridge, United Kingdom; 6CEA, France
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S128: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-057
Investigation of the metabolic stability of new silicon-based fluoride acceptor 18F-tracers S. S. Otaru1, S. Imlimthan2, K. Helariutta2, K. Wähälä2, M. Sarparanta2, A. Airaksinen2 1Department of Chemistry, University of Helsinki, Finland; 2University of Helsinki, Finland
S 211
P-058
Radiosynthesis of [18F]mFBG on Trasis AllinOne for PET imaging in children with neuroendrocrine malignancies E. D. C. Branquinho1, J. Fouque1, M. Luporsi2, C. Beauvineau3, T. C. Mounat2, S. Blondeel-Gomes1, O. Madar1 1Department of Radiopharmacology, Institut Curie, France; 2Department of Imagery, Nuclear Medicine Unit, Institut Curie, France; 3Research center, CMIB, UMR9187/U1196, Institut Curie, France
S 212
P-059
2-[18F]Fluoro-5-iodopyridine ([18F]FIPy): A novel reactive prosthetic group for the fast site specific radiolabeling via Pd-catalyzed cross coupling reactions M. A. Omrane1, B. Zlatopolskiy2, B. Neumaier3 1Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Jülich, Germany. Department of Nuclear Medicine, University Medical Center Freiburg, and Division of Radiopharmaceutical Development, German Cancer Consortium (DKTK), partner site Freiburg, Germany; 2Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany; 3Forschungszentrum Jülich GmbH, Germany
S 213
P-060
[18F/19F] Isotopic exchange radiolabeling of pentafluorosulfanyl groups H. Hiscocks1, J. Hill2,5, G. Pascali3,6, P. Scott4, A. Brooks2, A. Ung1 1University of Technology Sydney, Australia; 2University of Michigan, United States; 3ANSTO, Australia; 4The University of Michigan, United States; 5University of Queensland, Australia; 6University of Sydney, Australia
S 214
P-061
Synthesis and preliminary preclinical evaluation of a 18F-fluorinated quaternary α-aminoacid-based arginase inhibitor G. Clemente1, I. Antunes2, S. Kurhade3, A. V. Waarde1, A. Dömling3, P. Elsinga1 1University Medical Center Groningen, Netherlands; 2UMCG, Netherlands; 3Department of Drug Design, University of Groningen, Netherlands
S 214
P-062
A new method for synthesis of 18F-FDG: Using integrated flow board with micro reactor W. Liang1, Y. Shao2, J. Liu3, D. Liu3, J. Lv3 1Department of Nuclear Medicine, No. 940 Hospital of the Joint Logistic Support Force, Chinese People’s Liberation Army, China; 2Department of Nuclear Medicine, No. 960 Hospital of the Joint Logistic Support Force, Chinese People’s Liberation Army, Jinan, Shandong, China; 3Shaanxi Zhengze Bio-Science & Technology Co., LTD, Xian 710200, Shaanxi, China
S 216
P-063
Cu-Mediated Aminoquinoline-Directed Radiofluorination of Aromatic C-H Bonds with K18F S. J. Lee1, K. Makaravage1, A. Brooks1, M. Sanford1, P. Scott2 1University of Michigan, United States; 2The University of Michigan, United States
S 216
P-064
Radiofluorination of pyridinyl iodonium salts for the preparation of 3/5-[18F] fluoropyridines: Optimization, mechanism investigation and scope C. Perrio2, M. Pauton, C. Aubert1,2, G. Bluet2, F. Gruss-Leleu2, S. Roy2 1Normandie University, France; 2Sanofi, France
S 217
P-065
Aryltrialkylstannanes are viable substrates for [18F]trifluoromethylation B. Y. Yang1, S. Telu1, X. Zhang2, S. Liang3, V. Pike1 1National Institute of Mental Health, United States; 2MGH/Harvard, China; 3MGH/Harvard, United States
S 218
P-066
A Combinatorial Library of Fluorine-Integrated Peptides for PET Imaging Agent Discovery E. Murrell, L. Luyt University of Western Ontario, Canada
S 219
P-067
A novel PET probe for in vivo imaging of free radical species V. Akurathi1, L. Floryance1, V. Pawar2, C. North1, D. Dick1 1University of Iowa, United States; 2Synthink Research Chemicals, India
S 221
P-068
Using novel radiofluorination methodologies to advance the development and translation of 18F-labeled PET tracers: The Yale experience Z. Cai1, S. Li2, W. Zhang3, N. Nabulsi4, Y. Huang1 1PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States; 2Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States; 3Department of Nuclear Medicine, West China Hospital, Sichuan University, China; 4Yale PET Center, United States
S 222
P-069
Arabinofuranose-derived PET radiotracers for sensing gram-negative bacteria in vivo M. Kalita, M. Stewart, J. Luu, J. Blecha, H. VanBrocklin, M. Evans, M. Ohliger, O. Rosenberg, D. Wilson University of California, San Francisco, United States
S 223
P-070
Preclinical evaluation of [18F] Tetrafluoroborate ([18F] TFB) radiopharmaceutical, using a semi automatically method. J. C. Manrique-Arias1, V. Rodriguez2, F. Garcia, D. Garduño 1Universidad Nacional Autónoma de México (UNAM), Mexico; 2UNAM, Mexico
S 224
P-071
Automated production of high specific activity [18F]6F-l-DOPA using a TRACERLab FXFN synthesis module A. Mossine1, S. Tanzey1, A. Brooks1, B. Henderson1, M. Skaddan2, M. Sanford1, P. Scott3 1University of Michigan, United States; 2AbbVie, United States; 3The University of Michigan, United States
S 225
P-072
Improved synthesis and quality control of [18F]PSMA-1007 A. Fasel, R. Martin, D. Baumgart, S. Weidlich, M. Mueller ABX Advanced Biochemical Compounds, Germany
S 226
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S129
P-073
Two-step 18F-labeling of Pept-ins™ targeting S. aureus via [18F]F-py-TFP K. Luyten1, T. Thibangu, F. Cleeren2, L. Khodaparast, L. Khodaparast, F. Rousseau3, J. Schymkowitz3, G. Bormans4 1Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit Leuven, Belgium; 2Radiopharmaceutical Research, Department of Pharmacy and Pharmacology, University of Leuven, Belgium; 3VIB Switch Laboratory, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, Leuven, Belgium; 4Katholieke Universiteit Leuven, Belgium
P-074
An open-label, single arm trial to explore potential imaging biomarkers correlate with efficacy of bevacizumab combined with conventional therapy in newly diagnosed glioblastoma L. Li, S. Yuan, J. Yu, N. Liu, H. Zhang, R. Tao, Z. Fu, S. Zhao, L. Xu, Y. Liu, Y. Gao Shandong Cancer Hospital and Institute, China
S 227
S 229
P-075
High-purity synthesis of [18F]-AlF-pHLIP using semi-preparative HPLC S. Carlin1, E. Burnazi2, S. Lyashchenko2, J. Lewis1 1Memorial Sloan Kettering Cancer Center, United States; 2MSKCC, United States
S 230
P-076
18F- PEG2-OTSSP167 inhibits maternal embryo leucine zipper kinase for PET imaging of triple-negative breast cancer
S 231
H. Jia1,2, F. Hu1,2 1Memorial Sloan Kettering Cancer Center, United States; 2MSKCC, United States P-077
Experimental study on the diagnosis of hepatocellular carcinoma by 18F-NOTA-NSC-GLU PET/CT X. Xiang The First Affiliated Hospital of Sun Yat-Sen University
S 232
POSTER CATEGORY: RADIOCHEMISTRY - 11C AND OTHER POSITRON EMITTERS P-078
Development of a novel PET ligand for imaging leucine rich repeat kinase 2 Z. Chen1, T. Shao1, H. Fu1, L. Wang2, T. Collier3, H. Wey1, Y. Shao4, L. Josephson1, S. Liang1 1MGH/Harvard, United States; 2The first affiliated hospital of Jinan University, China; 3Advion Inc, United States; 4University of Oklahoma, United States
S 232
P-079
Base effect on the radiosynthesis of P2X7R radioligands [11C]GSK1482160 and its halo-analogs M. Gao, M. Wang, J. Meyer, J. Peters, P. Territo, H. Zarrinmayeh, Q. Zheng Indiana University School of Medicine, United States
S 233
P-080
Preclinical evaluation of [11C]AZ13713945 and its analogs as muscarinic acetylcholine receptor M4 PET ligands X. Deng1, A. Hatori2, T. Shao1, K. Kumata2, Z. Chen1, Y. Shao3, S. Sun4, L. Josephson1, M. Zhang2, S. Liang1 1MGH/Harvard, United States; 2Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3University of Oklahoma, United States; 4College of Nuclear Technology & Chemistry and Biology, Hubei University of Science and Technology, China
S 235
P-081
Immuno-PET imaging with 89Zr-atezolizumab in low and high PD-L1 expressing renal cell carcinoma patient-derived xenograft models G. Hao1, A. Mulgaonkar1, L. Woolford1, K. Nham1, B. Guan1, J. Brugarolas1, X. Sun2 1UT Southwestern Medical Center, United States; 2University of Texas Southwestern Medical Center, United States
S 236
P-082
An original radio-biomimetic synthesis of 11C-nor-buprenorphine for PET imaging F. Caillé1, S. Auvity2, M. Goislard1, S. Goutal2, N. Tournier2, B. Kuhnast1 1Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 2CEA, France
S 237
P-083
Pd catalyzed cross-coupling of [11C]MeLi and its application in the synthesis and evaluation of a potential PET tracer for the vesicular acetylcholine transporter (VAChT) H. Helbert1, B. Wenzel2, W. Deuther-Conrad, G. Luurtsema3, W. Szymanski, P. Brust2, B. Feringa, R. Dierckx4, P. Elsinga3 1UMC Groningen, Netherlands; 2Helmholtz-Zentrum Dresden-Rossendorf, Germany; 3University Medical Center Groningen, Netherlands; 4UMCG, Netherlands
S 238
P-084
A mild method to activate molecular sieve 13X for [11C]carbon dioxide entrapment and release S. Lu1, J. Hong2, W. Miller, V. Pike3 1National Institutes of Health, United States; 2National Institute of Health, United States; 3National Institute of Mental Health, United States
S 239
P-085
CuI-mediated 11C-cyanation of (hetero)aromatic bromide and synthesis of [11C]perampanel H. Ishii1, T. Okamura2, M. Zhang3 1Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
S 240
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S130: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-086
Synthesis and radiopharmacological evaluation of a C-11-labeled azadipeptide nitrile inhibitor for targeting cysteine cathepsins M. Laube1, M. Frizler2, R. Wodtke3, C. Neuber4, R. Bergmann4, M. Bachmann3, M. Gütschow2, J. Pietzsch5, R. Loeser6 1Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany; 2Pharmaceutical Institute, Pharmaceutical Chemistry I, Rheinische Friedrich-Wilhelms-Universität, Germany; 3HelmholtzZentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 4Helmholtz-Zentrum Dresden-Rossendorf, Germany; 5Helmholtz-Zentrum Dresden-Rossendorf, Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Germany; 6Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany
S 241
P-087
New trends in cross-coupling 11C-methylation F. Liger1, T. Iecker2, C. Tourvieille2, D. le Bars3, T. Billard1 1CNRS–CERMEP, France; 2CERMEP, France; 3CERMEP Imgerie du Vivant, France
S 242
P-088
Rhodium-catalyzed addition of organozinc iodides to [11C]isocyanates B. Mair, M. Fouad1, U. Ismailani, B. Rotstein2 1University of Ottawa, Canada; 2University of Ottawa & University of Ottawa Heart Institute, Canada
S 242
P-089
Facile radiosyntheses of [11C]tetrazoles and [11C]triazines from (hetero)arylborons Z. Zhang, T. Niwa, Y. Watanabe, T. Hosoya RIKEN Center for Biosystems Dynamics Research, Japan
S 243
P-090
Expanding the scope of carbon-11 labelled ureas: A universal method to access short-lived click reagents for in vivo PET imaging S. Bongarzone, A. Ferocino, A. Gee King’s College London, United Kingdom
S 244
P-091
Rapid one-step carbon-11 carboxylation of terminal alkynes using [11C]CO2. F. Goudou, S. Bongarzone, A. Gee King’s College London, United Kingdom
S 245
P-092
Synthesis of [11C]nicotinamide analogs for imaging of nicotinamide N-methyltransferase activity T. Okamura1, H. Ishii2, T. Kikuchi3, M. Okada, H. Wakizaka, M. Zhang4 1National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3National Institute for Quantum and Radiological Science and Technology, Japan; 4Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
S 246
P-093
Novel 11C-labeled and 18F-labeled allosteric modulators for M4 imaging X. Deng1, Z. Chen1, X. Zhang2, T. Shao1, S. Sun3, Y. Shao4, L. Josephson1, S. Liang1 1MGH/Harvard, United States; 2MGH/Harvard, China; 3College of Nuclear Technology & Chemistry and Biology, Hubei University of Science and Technology, China; 4University of Oklahoma, United States
S 246
P-094
Challenge of [11C]pirenzepine radiosynthesis: structure analysis of a novel rearrangement product M. Ozenil, L. Skos, A. Roller, C. Vraka, H. Spreitzer, M. Mitterhauser, M. Hacker, W. Wadsak, V. Pichler Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria
S 248
P-095
Application of new positron imaging agent 68Ga-pentixafor PET/CT in primary aldosteronism J. Ding, L. Yaping, P. Qingqing, L. Fang, T. Anli, Z. Yushi, H. Li Chinese Academy of Medical Science & Peking Union Medical College, Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, China
S 249
P-096
A “Universal” Method for Rapid 11C-Radiolabeling of PSMA Targeted Ligands via [11C]CO2 Fixation J. Downey, F. Goudou, S. Bongarzone, A. Gee King’s College London, United Kingdom
S 250
P-097
A [11C]CO dispensing system for fast and efficient screening of carbon-11 carbonylation reactions B. van der Wildt, B. Shen, F. Chin Stanford University, USA
S 252
P-098
Novel carbon-11 radiolabelling of Pt, Pd, and Ru complexes using [11C]CS2: Towards applications in PET S. Cesarec1, C. Plisson2, P. Miller1 1Imperial College London, UK; 2Imanova Limited, UK
S 252
P-099
In-loop synthesis of [11C] -methionine M. Stewart, S. Jivan, J. Blecha, T. Hayes, H. VanBrocklin, M. Ohliger, O. Rosenberg, D. Wilson University of California, San Francisco, USA
S 254
P-100
A facile method for the preparation of [11C]cyanide from [11C]methyl iodide T. Kikuchi1, M. Zhang2, A. Gee3 1National Institute for Quantum and Radiological Science and Technology, Japan; 2Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3King’s College London,United Kingdom
S 254
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23rd International Symposium on Radiopharmaceutical Sciences
Poster: S131
P-101
Facilitated troubleshooting in (+)-[11C]PHNO synthesis by investigation of reagents, byproducts, and intermediates S. Pfaff1, C. Philippe2, L. Nics2, N. Berroteran-Infante1, K. Pallitsch3, C. Rami-Mark1, A. Weidenauer4, U. Sauerzopf4, M. Willeit4, M. Mitterhauser2, M. Hacker1, W. Wadsak2, V. Pichler2 1Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; 2Medical University of Vienna, Austria; 3Institute of Organic Chemistry, University of Vienna, Austria; 4Department of Psychiatry and Psychotherapy, Division of General Psychiatry, Medical University of Vienna, Vienna, Austria
S 255
P-102
Some aspects on the specific activity of CH3I B. Nebeling Synthra GmbH, Hamburg, Germany
S 257
POSTER CATEGORY: RADIOCHEMISTRY - RADIOMETALS P-103
Preparation and quality control of ready for injection [64Cu]copper dichloride solution for theranostic applications M. Avila-Rodriguez Universidad Nacional Autonoma de Mexico (UNAM), Mexico
S 258
P-104
Bispidine chelators for radiometals M. Starke, K. Rück, P. Comba Heidelberg University, Germany
S 258
P-105
Copper (II) coordination chemistry of C- and N-alkylated cyclam ligands. Advantage of the triazole unit and application in 64-Cu radiochemistry K. Selmeczi1, W. Bouali1, E. Wenger2, A. Ouadi3, N. P. Moïse1 1Université de Lorraine - L2CM UMR 7053, France; 2Université de Lorraine - CRM2 UMR 7036, France; 3Institut Pluridisciplinaire Hubert Curien, CNRS, France
S 259
P-106
A one-pot synthesis of DOTA-hydrazide via HATU-mediated coupling reaction for biomacromolecule radiolabeling S. Imlimthan, A. Airaksinen, M. Sarparanta University of Helsinki, Finland
S 260
P-107
Perfluorinated calixarene shuttles for radium and barium F. Reissig, D. Bauer, H. Pietzsch, J. Steinbach, C. Mamat Helmholtz-Zentrum Dresden-Rossendorf, Germany
S 261
P-108
Purification of gallium-67 for (pre)clinical application as surrogate for gallium-68 E. de Blois, C. Koyuncu, Y. Seimbille Erasmus MC, Netherlands
S 262
P-109
PET-Imaging of PD-L1 expression for immunotherapy monitoring S. Stadlbauer1, M. Schaefer1, U. Bauder-Wuest1, K. Kopka2 1German Cancer Research Center, Germany; 2German Cancer Research Centre (dkfz), Germany
S 263
P-110
Preparation and preliminary evaluation of gallium-68 labeled PSMA inhibitor [68Ga]-NOTA-ANCP-PSMA K. Wen, H. Ji, C. Haiping German Cancer Research Center (DKFZ), Germany
S 264
P-111
SRadium-doped BaSO4 nanoparticles for future targeted alpha therapy F. Reissig, H. Pietzsch, J. Steinbach, C. Mamat Helmholtz-Zentrum Dresden-Rossendorf, Germany
S 265
P-112
Synthesis of estrogen derivatized cyclopentadienyl complexes of technetium and rhenium with potential radiopharmaceutical application M. Tejeria1, D. Hernández2, R. Lengacher2, J. Giglio1, A. M. Rios3, R. Alberto4 1Chemistry University, Uruguay; 2Chemistry Department, University of Zurich, Switzerland; 3Faculty of Chemistry, UdelaR, Uruguay; 4University of Zurich, Switzerland
S 266
P-113
H2CHXhox, cyclohexane reinforced chelating ligand for Ga3+ and Cu2+ X. Wang1, M. D. G. Jaraquemada-Pelaez1, C. Rodríguez-Rodríguez2, Y. Cao2, J. Pan5, K. Saatchi2, B. Patrick3, U. Häfeli4, K. Lin5, C. Orvig2 1Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, BC, Canada; 2University of British Columbia, Canada; 3Department of Chemistry, University of British Columbia, Canada; 4Faculty of Pharmaceutical Sciences, University of British Columbia, Canada; 5BC Cancer Research Centre, Canada
S 267
P-114
H5decaox: A high denticity “ox” ligand for diagnostic and therapeutic radiometals L. Southcott1, M. D. G. Jaraquemada-Pelaez2, N. Choudhary2, X. Wang2, V. Radchenko3, C. Orvig4, P. Causey5, R. Perron5 1Department of Chemistry, University of British Columbia, Canada; 2Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, BC, Canada; 3TRIUMF, Canada; 4University of British Columbia, Canada; 5Canadian Nuclear Laboratories (CNL), Canada
S 268
P-115
[68Ga]Ga-HBED-CC-DiAsp: A new renal function imaging agent S. Shi1, L. Zhang1, A. Zhang1, H. Hong1, Z. Wu2, Z. Zha3, S. R. Choi4, L. Zhu5, H. Kung3 1College of Chemistry, Beijing Normal University, China; 2Beijing Institute of Brain Disorders, Capital Medical University, China; 3University of Pennsylvania, USA; 4Five Eleven Pharma, USA; 5Beijing Normal University, China
S 269
P-116
Synthesis of novel technetium-99m tricarbonyl-HBED-CC complexes and structural prediction in solution by density functional theory calculation S. Shi1, L. Yao1, Z. Zha2, M. Sun1, L. Zhu3, D. Fang1, H. Kung2 1College of Chemistry, Beijing Normal University, China; 2University of Pennsylvania, USA; 3College of Chemistry, Beijing Normal University, China
S 271
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S132: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-117
A simple kit-based preparation of [68Ga]Ga-P15-041: A novel bone imaging agent H. Hong1, A. Zhang1, S. Shi1, Z. Zha2, Z. Wu3, J. Qiao1, K. Ploessl2, L. Zhu4, H. Kung2 1College of Chemistry, Beijing Normal University, China; 2University of Pennsylvania, USA; 3Beijing Institute of Brain Disorders, Capital Medical University, China; 4Beijing Normal University, China
S 272
P-118
A novel method for radiolabeling monoclonal antibodies under mild conditions with the therapy nuclide lutetium-177 using AAZTA5-en-Squaric acid as chelator-conjugate E. S. Moon1, B. Klasen1, F. Roesch2 1Johannes Gutenberg University Mainz, Institute of Nuclear Chemistry, Germany; 2Johannes Gutenberg University, Germany
S 273
P-119
New trans-[M (SS)(isc)2(CO)2], [M (SS)(P)2(CO)2] and [M (SS)(isc)(P)(CO)2], (M = 99mTc/Re) mixed ligand complexes M. Ischyropoulou1, I. Roupa1, A. Papasavva1, A. Shegani2, M. Kaplanis1, K. Makripidi1, C. Kiritsis1, D. Ischyropoulos1, C. Raptopoulou1, V. Psycharis1, A. Chiotellis1, M. Pelecanou3, I. Pirmettis1, M. Papadopoulos1 1NCSR ‘DEMOKRITOS’, Greece; 2University of Missouri Research Reactor Center (MURR), USA; 3NCSR ‘Demokritos’ “Institute of Radioisotopes”, Greece
S 274
P-120
A novel squaric acid based AAZTA5.SA.KuE conjugate for PET and radiotherapy of prostate cancer: gallium-68, scandium-44, copper-64, and lutetium-177 T. Grus1, L. Greifenstein1, J. Sinnes1, F. Roesch2 1Institute of Nuclear Chemistry, Johannes Gutenberg University Mainz, Germany; 2Johannes Gutenberg University, Germany
S 276
P-121
The first Curie-quantity production of [68Ga]Ga-PSMA-HBED-CC C. Schweinsberg1, A. Johayem1, A. Llamazares1, K. Gagnon2 1University Hospital Zurich, Switzerland; 2GE Healthcare, Sweden
S 276
P-122
Investigation of intramolecular complexes of hydroxyalkylamines for chelation of 68Ga with PSMA-HBED-CC V. Timofeev1, D. Antuganov1, M. Zykov1, K. Timofeeva1, Y. Kondratenko2 1Almazov National Medical Research Centre, Russian Federation; 2Grebenshchikov Institute of Silicate Chemistry RAS, Russian Federation
S 277
P-123
Synthesis of a Glu-urea-Lys based titanium-45-labelled PSMA inhibitor for positron emission tomography K. Pedersen, K. M. Nielsen, M. Jensen, F. Zhuravlev Center for Nuclear Technologies, Technical University of Denmark, Denmark
S 279
P-124
Novel radiochemical isolation strategy for the production of no-carrier-added Ba-133m E. Aluicio-Sarduy1, C. Kutyreff2, P. Ellison3, T. Barnhart3, R. Nickles4, J. Engle1 1University of Wisconsin-Madison, USA; 2Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, USA; 3University of Wisconsin, USA; 4University of Wisconsin Medical Physics, USA
S 280
P-125
Production of [62Zn]citrate and [62Cu]glycine with a modified 62Zn/62Cu generator system Z. Yu1, D. Parker2, A. Gee1, P. Blower1 1King’s College London, UK; 2School of Physics and Astronomy, University of Birmingham, UK
S 281
P-126
A small molecule 64copper-2-phenylethyenesulfonamide (64Cu-PES) as a novel HSP70 targeted imaging agent P. Ghosh UT Health Science Center-Houston, Texas, USA
S 281
P-127
H4picoopa: An acyclic high-denticity chelator for targeted alpha therapy L. Wharton1, M. D. G. Jaraquemada-Pelaez1, L. Southcott1, A. Robertson2, V. Radchenko, C. Orvig1, P. Schaffer2, P. Causey3, R. Perron3 1University of British Columbia, Canada; 2TRIUMF, Canada; 3Canadian Nuclear Laboratories (CNL), Canada
S 282
P-128
Evaluation of a new dicarboxy-monoamide-tetraaza-bifunctional chelator for rapid room temperature labeling of lead and copper radionuclides for radiopharmaceuticals M. Schultz1, M. Li1, J. Bjorklund1, M. Gabr1, D. Lee1, E. Sagastume2, F. Johnson2, F. C. Pigge1, S. Mason1, F. Boschetti3 1University of Iowa, USA; 2Viewpoint Molecular Targeting, Inc, USA; 3Chematech
S 283
P-129
Evaluation of radiation dose on 99Mo absorption of AG1-×8 resin J. Liang, Y. Shen, X. Xiang, Y. Wu, N. Yu Department of Isotope, China Institute of Atomic Energy, China
S 284
P-130
Technetium complexes of 2-hydrazinopyridine and hydrazinonicotinamide (HYNIC)-conjugated peptides. Insights from LC-MS and electrophoresis studies J. Pijarowska-Kruszyna, A. Jaroń, M. Orzełowska, M. Maurin, R. Mikolajczak, P. Garnuszek National Center for Nuclear Research, Radioisotope Center POLATOM, Poland
S 285
P-131
A novel FAP-inhibitor containing squaric acid coupled DOTA: Synthesis and preliminary evaluation E. Eppard1, L. Greifenstein2, E. S. Moon2, T. Grus2, V. Kramer3, F. Roesch4 1PositronPharma, Chile; 2Johannes Gutenberg University Mainz, Institute of Nuclear Chemistry, Germany; 3Positronpharma SA, Chile; 4Johannes Gutenberg University, Germany
S 286
P-132
HPLC for determination of unbound gallium-68 in radiopharmaceuticals: Pitfalls and solutions A. Larenkov, A. Maruk, G. Kodina State Research Center - Burnasyan Federal Medical Biophysical Center, Russian Federation
S 287
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23rd International Symposium on Radiopharmaceutical Sciences
Poster: S133
P-133
New phosphonic acids as components of bone seeking radiopharmaceuticals G. Tsebrikova1, V. Baulin1,2, V. Ragulin2, V. Solov’ev1, A. Maruk1,3, E. Lyamtseva3, A. Malysheva3, A. Larenkov3, M. Zhukova3, A. Lunev3, O. Klementyeva3, G. Kodina3, Y. Wang4, A. Tsivadze1 1Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Federation; 2Institute of Physiologically Active Compounds, Chernogolovka, Russia Severny proezd, Russian Federation; 3Burnasyan Federal Medical Biophysical Center, Russian Federation; 4Harbin Institute of Technology, China
S 287
P-134
Zirconium-89 solutions: Preparation, formulation, analysis, and comparison of applicability for radiopharmaceutical purposes A. Larenkov, V. Bubenschikov, A. Makichyan, G. Kodina State Research Center, Burnasyan Federal Medical Biophysical Center, Russian Federation
S 289
P-135
Investigations on the mechanism of simultaneous photochemical conjugation and radiolabelling of proteins with modified arylazides M. Gut1, L. Eichenberger2, J. Holland1 1Department of Chemistry, University of Zürich, Switzerland; 2University of Zürich, Switzerland
S 289
P-136
Synthesis of a photoactivatable aryl-azide-SAAC ligand and in vivo studies with the photochemically conjugated [99mTc][Tc (CO)3(SAAC-azepin)]-MetMAb F. Gribi, J. Holland Department of Chemistry, University of Zurich, Switzerland
S 291
P-137
Synthesis and biological evaluation of Tz-PEG4-HBEDCC-68Ga confirming its capability for bioorthogonal and pretargeted imaging E. Lambidis1, D. Lumen1, E. Honkaniemi1, K. Kepsu1, T. Koivula2, B. B. Lopez1, M. Sarparanta1, A. Airaksinen1 1University of Helsinki, Finland; 2Cyclotron Unit, Medical Imaging Center, HUS Helsinki University Hospital, Finland
S 292
P-138
Effect of excipients on gallium-68 species content in radiopharmaceutical preparations: Old biases and new data A. Larenkov1, E. Arefyeva2, A. Makichyan1, A. Maruk1, M. Rakhimov1 1State Research Center, Burnasyan Federal Medical Biophysical Center, Russian Federation; 2Lomonosov Moscow State University, Russian Federation
S 293
P-139
Simultaneous photochemical conjugation and 89Zr-radiolabelling of antibodies for immuno-PET J. Holland, S. Klingler, M. Patra, L. Eichenberger University of Zürich, Switzerland
S 294
P-140
Tripodal N-centred phosphine ligands: Towards a novel donor set for 99mTc and 186/188Re radiopharmaceutical formulation S. Cooper1, T. Yue1, P. Miller1, M. Ma2, N. Long1 1Imperial College London, UK; 2King’s College London, UK
S 295
P-141
Production and applications of radiometal zirconium-89 J. H. Park, C. Vyas, J. Y. Lee, S. D. Yang, M. G. Hur Korea Atomic Energy Research Institute, Republic of Korea
S 296
P-142
Development of bifunctional N2O2 Schiff base ligands for Re (III) and Tc (III) radiopharmaceuticals J. Baumeister1, S. Jurisson2, H. Hennkens3, A. Mitchell1, R. Cadena1 1University of Missouri, USA; 2University of Missouri-Columbia, USA; 3University of Missouri Research Reactor Center and Department of Chemistry, USA
S 297
P-143
Characterization of yttrium hydroxycarbonate microparticles for [90Y]Y-based liquid brachytherapy agent development A. Charles1, G. Makris2, M. Embree2, D. Stalla3, S. Ellebracht4, J. Simón4, H. Hennkens1,2 1University of Missouri Department of Chemistry, USA; 2University of Missouri Research Reactor Center, USA; 3Electron Microscopy Core, University of Missouri-Columbia, USA; 4IsoTherapeutics Group, LLC, USA
S 298
P-144
Broken symmetry copper complexes of photoactive bis (thiosemicarbazone) ligands for chromophore enhancement of photoradiochemical kinetics J. E. Flores1, J. Holland2 1University of Zürich, Switzerland; 2Department of Chemistry, University of Zurich, Switzerland
S 299
P-145
HOPO: A potential chelator for use in 44Sc and 47Sc based theranostic agents M. Phipps1, V. Sanders2, A. Younes3, D. Medvedev2, J. Lewis4, C. Cutler2, L. Francesconi3, M. Deri5 1Graduate Center of the City University of New York, USA; 2Brookhaven National Laboratory, USA; 3Hunter College, USA; 4Memorial Sloan Kettering Cancer Center, USA; 5Lehman College, CUNY, USA
S 300
P-146
Automated production and purification of copper medical radioisotopes in a variable energy cyclotron using solid targets D. Niculae1, S. Ilie2, R. Leonte2, L. Chilug2, L. Craciun2 1Horia Hulubei National Institute for Physics and Nuclear Engineering, Romania; 2Radiopharmaceutical Research Centre, Horia Hulubei National Institute for Physics and Nuclear Engineering, Romania
S 301
P-147
Refining theranostic isotopes of germanium from irradiated cobalt-gallium targets C. Kutyreff1, P. Ellison2, E. Aluicio-Sarduy3, T. Barnhart2, R. Nickles4, J. Engle5 1Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, USA; 2University of Wisconsin, USA; 3University of Wisconsin-Madison, USA; 4University of Wisconsin Medical Physics, USA; 5Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
S 302
P-148
Tb-161 Purification by high performance ion chromatography (HPIC) from irradiated Gd-160 A. Burgoyne, M. Ooms, T. Cardinaels, D. Elema Belgian Nuclear Research Centre (SCK•CEN), Institute for Nuclear Materials Science, Belgium
S 303
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S134: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-149
Clinical implementation of cyclotron-based [68Ga]Ga-PSMA-11 at the University of Michigan M. Rodnick1, B. Hockley2, M. Piert1, K. Gagnon3, D. Parr3, J. Frigell3, C. Sollert3, P. Scott1 1University of Michigan, USA; 2Nuclear Medicine, Department of Radiology, University of Michigan, USA; 3GE Healthcare, Sweden
S 304
P-150
Site-specific radiolabeling of antibodies through enzyme-mediated oligosaccharide remodeling J. Wang1,2,3, T. Cole1,2,3, R. Phelan1,2,3, L. Miesbauer1,2,3, P. Devries1,2,3, D. Reuter1,2,3, H. Falls1,2,3, E. Digiammarino1,2,3, J. Ji1,2,3, R. Comley1,2,3, S. Finnema1,2,3 1University of Michigan, USA; 2Nuclear Medicine, Department of Radiology, University of Michigan, USA; 3GE Healthcare, Sweden
S 304
P-151
An optimised manual 64Cu-radiolabelling and purification method of [64Cu]CuSAR-bisPSMA; reformulation and radiostability for prospective automation and preclinical development L. Spare1, N. Zia2, P. Donnelly2, I. Greguric3, E. van Dam1, M. Harris1, N. Lengkeek3 1Clarity Pharmaceuticals, Australia; 2University of Melbourne, Australia; 3ANSTO, Australia
S 306
P-152
Pre-targeted glucose metabolism imaging of murine tumors with technetium-99m labelled dibenzocyclooctyne derivative J. Ding1,2,3, T. Chu1,2,3 1Clarity Pharmaceuticals, Australia; 2University of Melbourne, Australia; 3ANSTO, Australia
S 307
P-153
Abstract withdrawn
POSTER CATEGORY: RADIOCHEMISTRY - OTHER RADIONUCLIDES P-154
In vivo imaging of diesel exhaust particulates in mice via efficient radioactive iodine labeling of polycyclic aromatic hydrocarbon assemblies H. E. Shim, C. H. Lee, L. Song, J. Jeon Korea Atomic Energy Research Institute, Republic of Korea
S 309
P-155
Synthesis of 4-(4-[I-123]iodophenyl)piracetam, a potential SPECT agent for Parkinson’s disease M. Akula1, D. Blevins2, G. Kabalka1, D. Osborne1 1University of Tennessee Medical Center, USA; 2The University of Tennessee, GSM, USA
S 310
P-156
Radioiodinated EIPBA for PR targeting with enhanced nucleus uptake via phenylboronic acid conjugation F. Gao1,2, R. Zhuang1, J. Li1, Z. Guo2, X. Zhang2 1State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics and Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, China; 2Xiamen University, China
S 311
P-157
Production, formulation, and quality control of [13N]NH3 for clinical use P. Kumar, R. Joshi NIMHANS, India
S 312
P-158
TLR5 as a target for Flavopiridol effect on breast cancer in mice model D. Shi
S 313
P-159
Direct nucleophilic radioiodination and astatination of antibodies via pre-conjugated arylboronic acids M. Berdal1, L. Navarro2, C. Alliot4, M. Chérel1, A. Faivre-Chauvet5, J. Gestin1, F. Guérard3 1CRCINA, Inserm, CNRS, France; 2CRCINA, France; 3Université de Nantes, CRCINA, Nuclear Oncology group; 4Arronax, France; 5University of Nantes, France
S 314
POSTER CATEGORY: AUTOMATION/MICROFLUIDICS/PROCESS DEVELOPMEN P-161
Synthesis and validation of [18F]6ʺ-fluromaltotriose, a radiotracer for imaging bacterial infections T. Haywood, M. Namavari, D. Anders, S. Gambhir Stanford University, USA
S 315
P-162
A concentration method for efficient microscale one-pot radiosynthesis of [18F]FET and [18F]fallypride R. Iwata1, C. Pascali2, K. Terasaki3, Y. Ishikawa4, R. Harada5, S. Furumoto1, K. Yanai5 1Tohoku University, Japan; 2Fondazione IRCCS Istituto Nazionale Tumori, Italy; 3Cyclotron Research Center, Iwate Medical University, Japan; 4Cyclotron and Radioisotope Center, Tohoku University, Japan; 5Graduate School of Medicine, Tohoku University, Japan
S 316
P-163
Facile two-step one-pot automated radiosynthesis of [18F]FET suitable for clinical PET study of brain tumors M. Wang, B. Glick-Wilson, Q. Zheng Indiana University School of Medicine, USA
S 318
P-164
Radio-analytical RP-HPLC methods for synthesis monitoring and quality control of [18F]FET B. Glick-Wilson*, Q. Zheng, M. Wang Indiana University School of Medicine, USA
S 319
P-165
Automated synthesis of 5-[18F]fluoro-α-methyl tryptophan (5-[18F]F-AMT) J. Blecha1, T. Hayes1, L. B. Garcia2, W. Chou2, T. Huynh3, D. Beckford-Vera1, M. H. Barcellos-Hoff2, B. Franc1, H. VanBrocklin1 1University of California, San Francisco, USA; 2UCSF Helen Diller Comprehensive Cancer Center, USA; 3UCSF Radiology and Biomedical Imaging, USA
S 321
P-166
Automated radiosynthesis of (2S,4R)-4-[18F]fluoroglutamine for clinical application Y. Zhang1, L. Zhang1, Z. Wu2, J. Yang3, K. Ploessl4, Z. Zha4, L. Fei3, H. Zhu, L. Zhu5, Z. Yang6, H. Kung4 1College of Chemistry, Beijing Normal University, China; 2Beijing Institute of Brain Disorders, Capital Medical University, China; 3Department of Nuclear Medicine, Peking University Cancer Hospital, China; 4University of Pennsylvania, USA; 5Beijing Normal University, China; 6Peking University, China
S 322
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23rd International Symposium on Radiopharmaceutical Sciences
Poster: S135
P-167
Spirocyclic iodonium ylide (SCIDY)-mediated automatic radiolabeling of [18F]FDPA and validation for human use L. Wang1, S. Yao2, H. Zhu1, R. Tang3, H. Xu1, S. Liang4 1The First Affiliated Hospital of Jinan University, China; 2Department of PET-CT Diagnostic, Tianjin Medical University General Hospital, Tianjin, China; 3Guangzhou Hightech Radiopharmaceutical Co. Ltd, Guangzhou, China; 4MGH/Harvard, USA
S 323
P-168
Towards continuous cyclotron production of PET radiometals: Membrane-based liquid-liquid extraction in flow of gallium-68, copper-64, zirconium-89, and titanium-45 K. Pedersen, K. M. Nielsen, J. Fonslet, M. Jensen, F. Zhuravlev Center for Nuclear Technologies, Technical University of Denmark, Denmark
S 324
P-169
Stability of [18F]FE-PE2I C. Denholt1, S. Lehel1, J. Madsen2, N. Gillings3 1Department of Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Denmark; 2Copenhagen University Hospital, Denmark; 3Copenhagen University Hospital Rigshospitalet, Denmark
S 325
P-170
“In-loop” 18F-fluorination: A proof-of-concept study K. Dahl1, A. Garcia1, N. A. Stephenson2, N. Vasdev1,3 1Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health, Canada; 2Department of Chemistry, University of the West Indies, Mona, Jamaica; 3Department of Psychiatry, University of Toronto, Canada
S 326
P-171
Click chemistry on TracerLab: Towards GMP manufacturing of high molar activity F-18 PET tracers F. Pisaneschi1, B. Engel1, M. N. Uddin1, S. Gammon1, S. Fiacco2, D. Piwnica-Worms3, S. Millward1 1UT MD Anderson Cancer Center, USA; 2EvoRx Technologies Inc, United States; 3MD Anderson Cancer Center, USA
S 328
P-172
Automated radiosynthesis of [177Lu]Lu-PSMA-617 on the iPHASE MultiSyn module C. Wichmann1, U. Ackermann2, S. Poniger3, K. Young2, J. Chan2, M. Hofman4, J. Sachinidis2, A. Scott1 1Olivia Newton-John Cancer Research Institute, Australia; 2Austin Health, Australia; 3Austin Hospital, Australia; 4Peter MacCallum Cancer Centre, Australia
S 329
P-173
Automated synthesis of [18F]O6-[(4-[18F]fluoro)benzyl]guanine ([18F]pFBG) via [18F]-fluorobenzyl alcohol ([18F]4FBnOH) from an optimized copper mediated radiofluorination (CMRF) of 4-tributyltin-benzyl alcohol G. Bowden1, A. Franke2, B. Pichler2, A. Maurer1 1Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Germany; 2Werner Siemens Imaging Center, Germany
S 329
P-174
Automated radiosynthesis of O-(2-[18F]fluorothyl)-O-(4-nitrophenyl)methylphosphonate: A PET tracer surrogate of VX T. Hayes1, J. Blecha1, C. Thompson2, J. Gerdes3, H. VanBrocklin1 1University of California, San Francisco, USA; 2University of Montana, USA; 3Department of Biomedical and Pharmaceutical Sciences, University of Montana, USA
S 331
P-175
Simple and fully automatic production of [18F]fluorodeprenyl-D2 using FXFN chemistry module M. Kim1, S. J. Lee2, N. R. Ko1, D. H. Kim1, J. S. Kim2, S. J. Oh2 1Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Republic of Korea; 2Asan Medical Center, Republic of Korea
S 332
P-176
Simple and fully automatic production of (S)-[18F]28 using All-in-One chemistry module S. J. Lee1, E. Cho1, D. H. Kim2, M. Kim2, M. Cui3, J. S. Kim1, S. J. Oh1 1Asan Medical Center, Republic of Korea; 2Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Republic of Korea; 3Beijing Normal University, China
S 333
P-177
Automated synthesis of [18F]NAV4694 using GE TracerLab FX-N Pro in compliance with PIC/S GMP M. F. B. M. Noh1, E. Laurens, S. Y. Jeow1, R. Vedarethinam2, X. J. Wee1, F. Z. B. Fatholmoein4, G. Pek2, H. T. S. Ping1, D. Green2, V. K. Chiam1, K. Boodeea4, P. R. Doshi, A. Kulasi1, E. T. J. Hui2, A. Weekes1, E. Robins3 1Clinical Imaging Research Centre, Singapore; 2A*STAR-NUS Clinical Imaging Research Centre (CIRC), Singapore; 3Singapore Bioimaging Consortium, Singapore; 4National University of Singapore
S 333
P-178
Automated handling of carbon-11 waste gases M. Shadwell, M. Izard, N. Paneras, E. Hoffman, G. Perkins ANSTO, Australia
S 334
P-179
Automated cartridge remover for radioactive solid waste handling in radiopharmaceutical production M. Izard, L. Griffith, J. Markham, N. Paneras, G. Perkins ANSTO, Australia
S 335
P-180
First in Southeast Asia (Singapore) clinical study utilizing an automated synthesis of [11C]metomidate on Tracerlab Fx C Pro in compliance with PIC/S GMP X. J. Wee1, M. F. B. M. Noh1, S. Y. Jeow1, R. Vedarethinam2, F. Z. B. Fatholmoein4, C. S. Lee1, G. Pek2, H. T. S. Ping1, D. Green2, E. Laurens, V. K. Chiam1, K. Boodeea4, P. R. Doshi, A. Kulasi1, E. T. J. Hui2, T. H. Puar1, A. Weekes1, E. Robins3 1Clinical Imaging Research Center, Singapore; 2A*STAR-NUS Clinical Imaging Research Centre (CIRC), Singapore; 3Singapore Bioimaging Consortium, Singapore; 4National University of Singapore
S 336
P-181
Fast HPLC quality control (QC) analysis of [18F]MK6240 using a core-shell particle column in partnership with Cerveau Technologies F. Z. B. Fatholmoein1, C. S. Lee1, G. Pek1, H. T. S. Ping1, M. F. B. M. Noh2, S. Y. Jeow2, R. Vedarethinam1, X. J. Wee3, D. Green1, E. Laurens1, V. K. Chiam4, K. Boodeea1, P. R. Doshi1, A. Kulasi2, E. T. J. Hui1, A. Weekes5, E. Robins6 1A*STAR-NUS Clinical Imaging Research Centre (CIRC), Singapore; 2Clinical Imaging Research Centre, Singapore; 3Clinical Imaging Research Center, Singapore; 4Clinical Imaging Research Centre Singapore, Singapore; 5Clinical Imaging Research Centre (CIRC), Singapore; 6Singapore Bioimaging Consortium, Singapore
S 336
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S136: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-182
Using a microdroplet reactor for rapid, nucleophilic synthesis of [18F]FDOPA J. Wang1, T. Holloway1, R. M. van Dam2 1UCLA, USA; 2UCLA Crump Institute for Molecular Imaging, USA
S 337
P-183
Optimization of the copper mediated [18F]radiofluorination (CMRF) of arylstannane precursors using a “design of experiments” (DoE) approach G. Bowden1, B. Pichler2, A. Maurer1 1Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Germany; 2Werner Siemens Imaging Center, Germany
S 339
P-184
Radiochemical and analytical aspects of inter-institutional quality control measurements on radiopharmaceuticals Erik de Blois1, Z. Zanger2, H. S. Chan3, M. Konijnenberg1, W. Breeman4 1Erasmus MC, Netherlands; 2TNO, Netherlands; 3AlfaRim Medical Holding BV, Netherlands; 4Erasmus University Medical Center, Netherlands
S 340
P-185
iMiLAB: A new cassette-based micro-fluidic platform for PET radiotracer synthesis—Initial results for the synthesis of [11C]methionine F. Goudou1,2,3, A. K. H. Dheere1,3, A. Gee1,3, V. Hourtane2, N. Masse2, Y. Cisse2 1King’s College London, UK; 2PMB, France; 3Synbiolab, France
S 341
P-186
Large-scale continuous-flow production of [18F]DCFPyl on a microfluidic synthesis module A. Poot1, D. van der Born2, S. Eeden1, D. Vugts1, A. Windhorst3, K. Koch2 1Amsterdam UMC, VU University, Netherlands; 2Future Chemistry Holding B.V., Netherlands; 3VU University Medical Center, Netherlands
S 342
P-187
Fully Automated MPLC-based manufacturing process and evaluation of potential stabilizers for flortaucipir F 18 injection J. Ogikubo, R. Ippisch, K. Fan, N. A. Lim, T. Benedum Avid Radiopharmaceuticals, Inc., a wholly owned subsidiary of Eli Lilly and Company, USA
S 344
P-188
Improved Florbetapir F 18 Injection manufacturing process W. Zhang1, A. Cagnolini2, X. Huang1, D. Pham1, C. Huang1, N. A. Lim1, T. Benedum1 1Avid Radiopharmaceuticals, Inc., a wholly owned subsidiary of Eli Lilly and Company, USA; 2Avid Radiopharmaceuticals, Inc., a wholly-owned subsidiary of Eli Lilly and Company, USA
S 345
P-189
Toward automation of a new process of dry nucleophilic [18F]fluoride production from [18F]triflyl fluoride N. Maindron1, Y. Joyard2, V. Tadino3, A. Pees4, A. Windhorst5, D. Vugts4 1ORA, Belgium; 2OOC, Belgium; 3ORA Neptis, Belgium; 4Amsterdam UMC, VU University, Netherlands; 5VU University Medical Center, Netherlands
S 345
P-190
New self-cleaning module for implementing process development and automation in 18F-radiochemistry N. Maindron1, Y. Joyard2, V. Tadino3 1ORA, Belgium; 2OOC, Belgium; 3ORA Neptis, Belgium
S 347
P-191
Synthesis of [11C]PK11195 and [11C]Ro15-4513 using a cassette-based method A. K. H. Dheere, A. Gee, M. Kovac King’s College London, UK
S 348
P-192
Use of a novel high-throughput microdroplet reaction platform for rapid optimization of [18F]fallypride synthesis conditions A. Rios1, J. Wang1, P. Chao1, R. M. van Dam2 1UCLA, USA; 2UCLA Crump Institute for Molecular Imaging, USA
S 348
P-193
High-throughput microdroplet radiochemistry platform to accelerate radiotracer development J. Jones1, A. Rios1, P. Chao1, J. Wang1, R. M. van Dam2 1UCLA, USA; 2UCLA Crump Institute for Molecular Imaging, USA
S 350
P-194
Radiosynthesis in microliter droplets at the 10 s of GBq scale—Impact of starting activity on reaction performance P. Chao1, J. Wang1, R. M. van Dam2 1UCLA, USA; 2UCLA Crump Institute for Molecular Imaging, USA
S 351
P-195
Adaptation and optimization of [18F]Florbetaben ([18F]FBB) radiosynthesis to a microdroplet reactor K. Lisova1, J. Wang1, A. Rios1, R. M. van Dam2 1UCLA, USA; 2UCLA Crump Institute for Molecular Imaging, USA
S 353
P-196
Optimization of reagents for automated isolation of Aastatine-211 from irradiated bismuth targets using tellurium-packed columns Y.Li1, D. Hamlin2, M. Chyan2, R. Wong2, T. Morscheck2, D. S. Wilbur1 1University of Washington, USA; 2University of Washington-Seattle, USA
S 354
POSTER CATEGORY: MULTIMODALITY IMAGING PROBES/NANOPARTICLES P-197
Development of platforms as dyes for combined [18F]PET/NIRF imaging T. Vucko, J. Ariztia1, N. P. Moïse2, S. Lamande-Langle3 1Université de Lorraine—UMR L2CM, France; 2Université de Lorraine—L2CM UMR 7053, France; 3Université de Lorraine, France
S 355
P-198
Elaboration of nanocarriers based on biocompatible polymers for the specific vectorisation of an imaging agent O. Malval, E. Vène1, P. Loyer1, S. Cammas-Marion1, N. Lepareur2 1ISCR, UMR 6226 CNRS, ENSCR, University of Rennes 1, France; 2Department of Nuclear Medicine, Centre Eugene Marquis, France
S 356
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23rd International Symposium on Radiopharmaceutical Sciences
Poster: S137
P-199
Dynamic PET imaging of tetrahedral DNA nanoparticles enables quantitative evaluation of kidney function via mathematical modeling D. Jiang1, D. Ni1, L. Kang2, W. Wei3, J. Engle4, W. Cai1 1University of Wisconsin, Madison, USA; 2Peking University First Hospital, China; 3Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, USA
S 357
P-200
Characterization of TCP-1 multimodality imaging probes in targeting colorectal cancer cells Z. Liu1, B. Gray2, C. Barber1, L. Wan1, A. Gmitro1, R. Liang1, K. Pak2, J. Woolfenden1 1University of Arizona, USA; 2Molecular Targeting Technologies, Inc., USA
S 358
P-201
Highly stable near infrared dye-cerasomes for synergistic chemo-photothermal therapy of colorectal cancer X. Zhang, R. Hou2, X. Liang1, F. Wang2,3, X. Li, X. Ma3 1Peking University Third Hospital, China; 2Peking University, China; 3Chinese Academy of Sciences, China
S 359
P-202
In situ conversion of Rose Bengal microbubble into nanoparticle for enhanced antitumor efficacy of sonodynamic therapy R. Hou2, X. Liang1, X. Zhang2, X. Li2, X. Ma3, F. Wang2,3 1Department of Ultrasound, Peking University Third Hospital, Beijing, China; 2Medical Isotopes Research Center and Department of Radiation Medicine, School of Basic Medical Sciences, Peking University, Beijing, China; 3Key Laboratory of Protein and Peptide Pharmaceuticals, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
S 360
P-203
Development of bimodal (PET/NIR) tumor tracers for non-invasive staging and fluorescence guided surgery of prostate cancer C. Kramer, T. Kanagasundaram, K. Kopka German Cancer Research Center (dkfz), Germany
S 361
P-204
Application of 64 Cu-Mn-PEG-d-MNP as a multimodal imaging contrast agent in tumor PDX model X. Lei, H. Zhu, Z. Yang German Cancer Research Center (dkfz), Germany
S 363
P-205
Development and preclinical evaluation of intrinsically radiolabeled [103Pd]AuPd nanoparticles in an injectable seed-forming system for nanobrachytherapy M. Fach2, F. Fliedner1, P. Kempen2, A. Hansen1, U. Köster3, A. Kjær4, T. Andresen, A. Jensen5, J. Henriksen2 1Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet and University of Copenhagen, Denmark; 2DTU Nanotech, Technical University of Denmark, Denmark; 3Institut Laue-Langevin, France; 4Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 5DTU Nutech, Technical University of Denmark, Denmark
S 364
P-206
Novel highly water-soluble and spherical boron nitride nanoparticles for boron neutron capture therapy L. Li, P. Du, J. Li, R. Zhang, Z. Liu Peking University, China
S 365
P-207
Peptide modified and radiometals loaded BP quantum dots for targeted PET imaging-guided tumor photothermal and photodynamic therapy K. Hu1, M. Zhang2, M. Hanyu3, L. Xie, Y. Zhang2 1National Institute of Radiological Sciences, Japan; 2Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Japan
S 366
P-208
Design and synthesis of an optical-PET bimodal imaging probe based on a NIR fluorophore and fluorine-18 S. Specklin, K. Solmont, B. Kuhnast Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France
S 367
P-209
Improving signal-to-noise ratio of hypoxia positron emission tomography (PET) imaging via polymeric delivery of [18F]fluoromisonidazole ([18F]FMISO) J. Goos1, N. Lengkeek2, I. Greguric2, M. Davydova1, M. Whittaker3, J. Quinn3, J. Baell3, J. Lewis1, T. Davis3 1Memorial Sloan Kettering Cancer Center, USA; 2ANSTO, Australia; 3Monash University, Australia
S 368
P-210
Synthesis and bioevaluation of 64Cu-labeled multifunctional gold nanoparticle conjugates as biovehicle for brain penetration L. Yang1,2, W. Qian3, Z. Zhong1,4, E. Ouchi1, P. J. Scott1, X. Shao1 1University of Michigan, USA; 2Pharmaceutical University, China; 3IMRA America, USA; 4Nankai University, China
S 368
P-211
Polyphenols-doped liquid metal nanodroplets for multimodal imaging J. Yan, X. Wang, D. Pan, R. Yang, Y. Xu, L. Wang, M. Yang Jiangsu Institute of Nuclear Medicine, China
S 369
P-212
99mTc/Gd- and PEG/FA-functionalized ultrasmall nanographene oxides for SPECT/MR imaging of cancers M. Wang, X. Zhou, T. Cao, Q. Shi, J. Zhang, Y. Zhang Fudan Univerisity Shanghai Cancer Center, China
S 370
P-213
Pharmacokinetics study of different sized iron oxide nanoparticles using simultaneous PET/MR J. Y. Park1, Y. H. Cho2, G. B. Ko3, K. Kim1, M. Suh, J. S. Lee1, Y. Lee2, D. S. Lee1, J. M. Jeong2 1College of Medicine, Seoul National University, Republic of Korea; 2Seoul National University Hospital, Republic of Korea; 3Naver, Republic of Korea
S 371
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S138: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-214
Chelator “free” Cu-64 radiolabeled carbon nitride 2D nanodots for PET imaging C. H. Kim1, H. Ahn2, K. Yerin1, S. Yoo1, K. C. Lee2, Y. J. Lee3, D. W. Kim4 1Department of Chemistry and Chemical Engineering, Inha University, Republic of Korea; 2KIRAMS, Republic of Korea; 3Korea Institute of Radiological & Medicals Sciences, Republic of Korea; 4Inha University, Republic of Korea
S 372
P-215
Radiolabeling of SUV size liposome with hexadecyl-4-[18F]fluorobenzoate ([18F]HFB) for tumor imaging S. H. Lee1, J. K. Park2, S. Lee3, J. Lee1, T. Ido1 1Neuroscience Research Institute, Gachon University, Republic of Korea; 2GAIHST, Gachon University, Republic of Korea; 3Department of Neuroscience, College of Medicine, Gachon University, Republic of Korea
S 373
P-216
Functionalised graphene nanoflakes as potential theranostic agents J. Lamb1, J. Holland2, C. Salzmann3, M. Rosillo-Lopez3, E. Fischer2 1University of Zurich, Switzerland; 2Department of Chemistry, University of Zurich, Switzerland; 3Department of Chemistry, University College London, UK
S 374
P-217
Regioselective labeling of biovectors with a novel dual-modality fluorescence/nuclear imaging probe K. Chen, Y. Seimbille Department of Radiology & Nuclear Medicine, Erasmus MC, Netherlands
S 375
P-218
The diagnostic efficiency of Bombesin functionalized superparamagnetic iron oxide nanoparticles in in breast cancer mouse models L. Li, H. Cai, L. Pan, X. Li, C. Wu, R. Tian, A. Kuang Department of Radiology & Nuclear Medicine, Erasmus MC, Netherlands
S 376
P-219
111In-radiolabeling
of tri-PEGylated porous silicon nanoparticles and their in vivo evaluation in murine 4T1 breast cancer model D. Lumen1, S. Näkki2, S. Imlimthan1, E. Lambidis1, M. Sarparanta1, W. Xu2, V. Lehto2, A. Airaksinen1 1University of Helsinki, Finland; 2Pharmaceutical Physics, Department of Applied Physics, University of Eastern Finland, Finland
S 377
P-220
64Cu-radiolabeled
polymeric micellar nanoparticles for targeting EGFR in cancer S. Mattingly1, I. Paiva2, M. Wuest3, M. Weinfeld2, A. Lavasanifar2, F. Wuest3 1Department of Oncology, University of Alberta, Canada; 2Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Canada; 3University of Alberta, Canada
S 378
P-221
Radioiodine labelled melanin nanoparticles for cancer brachytherapy X. Wang, J. Yan, M. Yang Jiangsu Institute of Nuclear Medicine, China
S 379
POSTER CATEGORY: RADIOLABELED COMPOUNDS - CARDIOLOGY P-222
Radiosynthesis of β-phenylethylamine derivatives for cardiac sympathetic nervous PET imaging Y. He, J. Zhang The PLA General Hospital, China
S 380
P-223
A 18F-PET probe for detection of oxidative stress in doxorubicin induced cardiotoxicity R. Yan King’s College London, UK
S 381
P-224
18F-Py-(cApoPep)2:
Apoptosis-targeting 18F-labeled PET tracer for imaging of the vulnerable plaque S. Y. Chu1, H. J. Jeong1, M. H. Kim1, M. H. Kim1, J. S. Kim1, B. S. Lee1, H. E. Park2, C. W. Kim2, J. Hyun2, K. Chang2, D. Y. Chi3 1Futurechem, Republic of Korea; 2The Catholic University of Korea, Republic of Korea; 3Department of Chemistry, Sogang University, Republic of Korea
S 382
P-225
Optimization of the automated synthesis of [11C]mHED - administered and apparent molar activities C. Vraka1, V. Pichler2, N. Berroteran-Infante1, T. Wollenweber1, A. Pillinger1, L. Fetty1, M. Hohensinner1, D. Beitzke, X. Li1, C. Philippe2, K. Pallitsch, M. Mitterhauser2, M. Hacker1, W. Wadsak2 1Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria; 2Medical University of Vienna, Austria
S 382
P-226
Synthesis and biological evaluation of fluorescence- and gallium-68-labeled anti-miR-21 E. Janssen, J. Fiedler, L. Langer, J. Thackeray, J. Bankstahl, T. Thum, F. Bengel, T. Ross Hannover Medical School, Germany
S 384
P-227
Vulnerable atherosclerotic plaques imaging by VEGFR PET Z. Yang, F. Li, D. Yelamanchili, C. Rosales, H. Pownall, K. Youker, D. Hamilton, Z. Li Hannover Medical School, Germany
S 385
P-228
Detecting vulnerable atherosclerotic plaques by 68Ga-labeled divalent cystine knot peptide L. Jiang1, Z. Cheng2 1Shanghai Pulmonary Hospital, Tongji University School of Medicine, China; 2Stanford University, USA
S 385
POSTER CATEGORY: RADIOLABELED COMPOUNDS - NEURO SCIENCES P-229
Improved synthesis of F18 MK6240, a PET tracer for neurofibrillary tangles M. Yu, C. Xu Houston Methodist Hospital Research Institute, USA
S 386
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23rd International Symposium on Radiopharmaceutical Sciences
Poster: S139
P-230
Radiosynthesis and in vitro characterization of an iodine-125 labeled radiotracer for α-synuclein Z. Tu1, X. Yue2, J. Gu2, Z. Luo2, C. Weng3, Z. Lengyel4, D. Dhavale2, P. Kotzbauer2, R. Mach5 1Department of Radiology, Washington University School of Medicine in Saint Louis, USA; 2Washington University in St. Louis School of Medicine, USA; 3Department of Radiology, University of Pennsylvania, USA; 4University of Pennsylvania School of Medicine, USA; 5University of Pennsylvania, USA
S 387
P-232
Dosimetry and toxicology of [18F]MC225 for measuring P-glycoprotein function at the blood-brain barrier in humans J. Toyohara1, M. Sakata1, T. Tago1, N. Colabufo2, G. Luurtsema3 1Tokyo Metropolitan Institute of Gerontology, Japan; 2Università degli Studi di Bari, Italy; 3University Medical Center Groningen, Netherlands
S 388
P-233
PET radiotracer translation from rats to higher species, using an increased-throughput in vivo evaluation strategy E. T. L’Estrade1, M. Xiong1, I. Petersen2, V. Shalgunov3, F. G. Edgar2, H. Hansen4, M. Erlandsson5, T. Ohlsson6, G. Knudsen4, M. Palner4, M. Herth7 1University of Copenhagen, Denmark; 2Department of Clinical Physiology, Nuclear Medicine and PET, University Hospital Copenhagen, Denmark; 3Department of Drug Design and Pharmacology, University of Copenhagen, Denmark; 4Neurobiology Research Unit, Copenhagen University Hospital, Denmark; 5Skanes University Hospital, Sweden; 6University Hospital of Lund, Sweden
S 389
P-234
Synthesis and characterization of a difluoroboron complex of fluorine-18 labeled curcumin derivative for β-amyloid plaque imaging H. Kim1, J. Y. Choi2, K. Lee2, B. Kim2, Y. S. Choe2 1Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Republic of Korea; 2Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Republic of Korea
S 390
P-235
Evaluation of the brain bio-distribution of [11C]BIIB104, an AMPA positive allosteric modulator in the living NHP brain using positron emission tomography S. Nag1, Z. Jia2, R. Arakawa1, K. Varnas1, M. Mohammad1, P. Datta1, D. Scott3, C. Shaffer3, M. Hutchison3, M. Kaliszczak3, L. Martarello3, C. Halldin1 1Karolinska Institute, Sweden; 2Clinical Neuroscience, Karolinska Institutet, Sweden; 3Biogen MA Inc, USA
S 391
P-236
Translational development of 18F-FC0324, a PET radiotracer for CB2 receptors imaging F. Caillé1, B. Attili2, S. Auvity3, M. Goislard1, J. Cayla1, G. Bormans4, M. Peyronneau1, B. Kuhnast1 1Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 2Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, UK; 3CEA, France; 4KU Leuven, Belgium
S 392
P-237
Assessment of adenosine agonist to improve drug delivery via the nasal to brain route of administration S. Khanapur1, V. Soh1, B. Ramasamy1, J. Goggi1, E. Robins2 1Singapore Bioimaging Consortium, A*STAR, Singapore; 2Singapore Bioimaging Consortium, Singapore
S 393
P-238
Synthesis and evaluation of a new PET ligand for imaging of monoacylglycerol lipase in brain W. Mori1, Y. Kurihara2, A. Hatori1, Y. Zhang1, M. Fujinaga1, M. Zhang1 1Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2SHI Accelerator Service, Japan
S 394
P-239
Radiosynthesis and evaluation of a negative allosteric modulator for the PET imaging of metabotropic glutamate receptor 2 in rat brain K. Kumata1, Y. Zhang1, A. Hatori1, T. Yamasaki1, Y. Kurihara2, N. Nengaki2, M. Zhang1 1Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2SHI Accelerator Service, Japan
S 395
P-240
Synthesis and evaluation of tropane-based, radiometal-labeled CNS tracers for the visualization of the dopaminergic transporter system S. Häseli1, F. Roesch2 1Institute for Nuclear Chemistry, Johannes Gutenberg-Universität Mainz, Germany; 2Johannes Gutenberg-Universität Mainz, Germany
S 396
P-241
Characterization of the rotenone mouse model of Parkinson’s disease using radioligands for the adenosine A2A receptor ([18F]FESCH) and the nicotinic α4β2 receptor ((−)-[18F]Flubatine) M. Toussaint1, M. Kranz1, S. Schröder2, T. H. Lai1, W. Deuther-Conrad1, S. Dukic-Stefanovic1, Q. Shang3,4, M. Patt5, H. Reichmann6, R. Funk7, O. Sabri5, F. Pan-Montojo3, P. Brust1 1Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany; 2Department of Research and Development, ROTOP Pharmaka GmbH, Dresden, Germany; 3Ludwig-Maximilians-Universität Munich, University Hospital GroßhadernNeurological Clinic & Polyclinic, Department of Neurology, Munich, Germany; 4Clinic of Neurology, Technische Universität Dresden, University Hospital Carl Gustav Carus, Dresden, Germany; 5Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany; 6Department of Neurology, Technische Universität Dresden, University Hospital Carl Gustav Carus, Dresden, Germany; 7Institute of Anatomy, Technische Universität Dresden, University Hospital Carl Gustav Carus, Dresden, Germany
S 397
P-242
Evaluation of fluorinated benzazepine and benzo[7]annulen-7-amine analogues for development as imaging agents for the GluN2B subunits of the N-methyl-D-aspartate receptor A. Haider1, H. Ahmed1, J. Varisco1, M. Stankovic1, R. Wallimann1, S. Gruber1, I. Iten1, J. Miguel4, C. Keller1, R. Schibli1, D. Schepmann2, L. Mu1, B. Wünsch2, S. Ametamey3 1ETH Zurich, Switzerland; 2Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Germany; 3Radiopharmacy, ETH Zurich, Switzerland; 4Esteve, Spain
S 398
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S140: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-243
Progress towards the first adenosine A1R full agonist PET radioligand M. Guo1, Z. Gao2, J. Ramsey3, T. Stodden3, C. Javdan4, L. Carvalho3, K. Jacobson2, S. W. Kim1, N. Volkow5 1National Institutes of Health/National Institute on Alcohol Abuse and Alcoholism, USA; 2Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, USA; 3Laboratory of Neuroimaging, National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, USA; 4University of Maryland College Park, USA; 5Laboratory of Neuroimaging, National Institute of Alcohol Abuse and Alcoholism, National Institute on Drug Abuse, National Institutes of Health, USA
S 399
P-244
Fluorine-18 radiolabelling and in vitro/in vivo metabolism of [18F]D4-PBR111 B. Fraser, M. Safavi-Naeini, A. Wotherspoon, A. Arthur, A. Nguyen, A. Parmar, H. Hamze, C. Day, D. Zahra, L. Matesic, E. Davis, G. Rahardjo, N. Yepuri, R. Shepherd, R. Murphy, T. Pham, V. Nguyen, P. Callaghan, P. Holden, M. Gregoire, T. Darwish Australian Nuclear Science and Technology Organisation, Australia
S 401
P-245
A novel imaging probe with selectivity for tau-oligomeric protein aggregates: In vitro evaluation and radiolabelling with fluorine-18 S. Thompson1, Y. Zhao1, O. Tietz2, F. Aigbirhio1 1University of Cambridge, UK; 2Molecular Imaging Chemistry Laboratory, Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
S 403
P-246
SPECT imaging of the glymphatic pathway with 111In-labeled ovalbumin in the rat brain V. Shalgunov1, T. Lilius2, B. Sigurðsson2, S. L. Bærentzen2, N. L. Hauglund2, M. Herth3, M. Palner4, M. Nedergaard2 1Department of Drug Design and Pharmacology, University of Copenhagen, Denmark; 2left for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 3University of Copenhagen, Sweden; 4Neurobiology Research Unit, Copenhagen University Hospital, Denmark
S 404
P-247
Preclinical evaluation in rats and non-human primates of [18F]GE387, a novel 18 kDa translocator protein (TSPO) PET radioligand with low binding sensitivity to human polymorphism rs6971 M. Hird1, F. Aigbirhio1, S. Thompson1, P. Scott2, A. Brooks2, D. Williamson1, N. K. Ramakrishnan1 1University of Cambridge, UK; 2University of Michigan, USA
S 406
P-248
Evaluation of in vitro and in vivo stability to support the preclinical and clinical development of [11C]MK-6884, a PET tracer for imaging M4 positive allosteric modulators K. Riffel1, W. Li2, Y. Wang1, T. Lohith2, M. Holahan2, H. Haley2, L. Tong2, R. Mazzola2, T. Bueters2, M. Koole3, K. Serdons3, K. Laere3, G. Bormans3, I. Lepeleire4, A. Basile2, E. Hostetler2 1Merck & Co., Inc., USA; 2Merck Research Laboratories, USA; 3KU Leuven, Belgium; 4Merck Sharp & Dohme (Europe) Inc., Belgium
S 407
P-249
Developing PET ligands targeting CNS stem cells for application in multiple sclerosis imaging S. Kealey1, D. Williamson1, N. K. Ramakrishnan1, A. G. de la Fuente2, F. Aigbirhio1, R. Franklin1 1University of Cambridge, UK; 2Queen’s University Belfast, UK
S 408
P-250
18F-labeled
azine derivatives as potential Aβ imaging agents for diagnosis of Alzheimer’s disease K. Zhou, Y. Li, F. Yang, M. Cui Beijing Normal University, China
S 409
P-251
A novel 18F-labeled D4-receptor ligand M. Willmann1, B. Neumaier2, J. Ermert3 1INM-5, Germany; 2Forschungszentrum Jülich GmbH, Germany; 3Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry, Germany
S 410
P-252
First-in-human evalua on of 18F-LY2459989, the first 18F-labeled PET radiotracer for imaging of the kappa opioid receptor S. Li1, M. Naganawa1, N. Nabulsi1, S. Henry1, M. Dias1, S. Najafzadeh1, H. Gao1, Z. Cai1, M. Kapinos1, J. Ropchan1, D. Matuskey1, Y. Huang1 1Yale PET left, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, USA; 2Yale PET left, USA
S 411
P-253
Quantitative structure-property relationship coupled with PET imaging predicts blood-brain-barrier transport of benzamides Y. Kang1, S. J. Lee2, J. Logan3, J. Hooker3, N. Volkow4, J. Fowler6, S. W. Kim5 1Howard University, USA; 2University of Michigan, USA; 3University of California, USA; 4Laboratory of Neuroimaging, National Institute of Alcohol Abuse and Alcoholism, National Institute on Drug Abuse, National Institutes of Health, USA; 5National Institute on Alcohol Abuse and Alcoholism/National Institutes of Health, USA; 6Brookhaven national Laboratory, USA
S 413
P-254
18F-labeled
styrylquinoxaline deriva ves as tau probes for PET L. Zhang, T. Xie, K. Zhou, M. Cui Beijing Normal University, China
S 413
P-255
Automated synthesis and separation of F-JNJC. Huang, G. Chen, W. Zhang, H. Kolb Beijing Normal University, China
S 414
P-256
[18F]FPEB for imaging mGluR5 is a P-gp substrate in the rodent J. Y. Choi1, K. R. Nam1, K. Jung1, S. J. Oh2, S. J. Han1, W. S. Chung1 1Korea Institute of Radiological and Medical Sciences, Republic of Korea; 2Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Republic of Korea
, a PET tracer for AMPA-TARPγ receptors
S 415
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S141
POSTER CATEGORY: RADIOLABELED COMPOUNDS - ONCOLOGY (IMAGING) P-257
PET imaging of human melanoma using Ga-68-DOTA-GGNle-CycMSHhex: Bench to bedside translation J. Yang1, J. Xu1, R. Gonzalez1, T. Lindner2, C. Kratochwil2, Y. Miao1 1University of Colorado Denver, USA; 2University Hospital Heidelberg, Germany
S 416
P-258
Preparation and evaluation of [18F]AlF-NOTA-NOC for PET imaging of neuroendocrine tumors J. Dam1, N. Langkjær1, C. Baun1, B. Olsen2 1Odense Universitetshospital, Denmark; 2Department of Nuclear Medicine, Odense University Hospital, Denmark HER2-targeted multimodal imaging of anaplastic thyroid cancer W. Wei1, D. Jiang2, D. Ni2, L. Kang3, J. Engle2, W. Cai2 1Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 2University of Wisconsin-Madison, USA; 3Peking University First Hospital, China
S 416
P-261
Construction of molecular probe 68Ga-DOTA-VAP and micro-PET/CT imaging study in GRP78 overexpressing tumor H. Zhao1, C. Wang1, J. Liu1, G. Huang1 1Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
S 418
P-262
Pretargeting of experimental prostate cancer using complementary L-oligonucleotides: Radiochemical and radiopharmacological characterization S. Weissflog1, F. Striese2, W. Sihver2, R. Bergmann2, M. Ullrich2, C. Neuber2, J. Pietzsch3, M. Bachmann4, J. Steinbach2, H.-J. Pietzsch2 1Department of Radionuclide Theragnostics, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 2Helmholtz-Zentrum Dresden-Rossendorf, Germany; 3Department Radiopharmaceutical and Chemical Biology, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 4Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany
P-260
S 417
S 419
P-263
Transport into the central nervous system of [ F]FLT and [ F]Fludarabine for brain tumors M. Tintas, S. Guillouet, M. Ibazizène, F. Fillesoye, C. Papamicaël, V. Levacher, L. Barré, F. Gourand Normandie University, France
S 420
P-264
68Ga-labeled GRPR- and VPAC R-specific peptide heterodimers—A favorable alternative to conventional monospecific peptides for tumor imaging S. Lindner1, L. Fiedler1, B. Waengler2, P. Bartenstein1, R. Schirrmacher3, C. Waengler4 1Department of Nuclear Medicine, University Hospital Munich, LMU, Germany; 2IKRN, Germany; 3Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, Canada; 4Biomedical Chemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany
S 421
P-265
[64Cu]Cu-NOTA- and [64Cu]Cu-NODAGA-6Ahx-RM2 GRPR-pep de antagonists for the targe ng of prostate cancer G. Makris1, A. Shegani1, M. Kuchuk2, R. Bandari, C. Smith2, H. Hennkens3,4 1University of Missouri Research Reactor le , USA; 2University of Missouri, USA; 3HSTMVH, USA; 4Department of Chemistry, University of Missouri Research Reactor le , USA
S 422
P-266
Stable site-specific labeling of nanobodies with 99mTc for SPECT imaging T. Liu1, Y. Wu1, H. Gao2, B. Jia2, F. Wang2 1Medical Isotopes Research le and Department of Radia on Medicine, Peking University, China; 2Peking University, China
S 423
P-267
Performance of a new preclinical PET/CT system for quantitative total-body dynamic imaging with low tracer doses C. Molinos1, S. Eigner1, T. Sasser1, D. Viertl2, S. Berr3, B. Kundu3, W. Gsell4, A. Bahadur1, S. Stark1, C. Correcher1, S. van Wyk1, J. Prior2, U. Himmelreich4, M. Heidenreich1 1Bruker BioSpin, Preclinical Imaging, Germany; 2Lausanne University Hospital, Switzerland; 3University of Virginia School of Medicine, USA; 4KU Leuven, Belgium
S 425
P-268
Preclinical evaluation of [18F]CETO as a tool for the study of the adrenals M. Jahan1, I. Silins2, P. Hellman2, A. Sundin3, M. Brown4, M. Gurnell5, F. Aigbirhio6, P. Nordeman7, G. Antoni7 1PET-Centre, Uppsala University Hospital, Uppsala, Sweden; 2Department of Surgery, Uppsala University Hospital, Uppsala, Sweden; 3Department of Radiology, Uppsala University Hospital, Uppsala, Sweden; 4Metabolic Research Laboratories, University of Cambridge, Cambridge, UK; 5William Harvey Heart Centre, Queen Mary University of London, London, UK; 6University of Cambridge, UK; 7Uppsala University Hospital, Sweden
S 427
P-269
C-C chemokine receptor type 2 (CCR2) targeted PET imaging in gene cally-engineered pancrea c cancer mouse model X. Zhang1, D. Sultan2, G. S. Heo1, H. Luehmann1, L. Detering1, L. Li1, F. Dehdash 1, K. Lim1, Y. Liu3 1Washington University in St. Louis, USA; 2Washington University School of Medicine, USA; 3Washington University, USA
S 428
P-270
Radioiodinated hyaluronan for imaging pancreatic stromal remodeling related to pancreatic cancer development Z. Liu, L. Wan, C. Barber, L. Han, L. Furenlid, J. Woolfenden University of Arizona, USA
S 429
P-271
Multi-mode molecular imaging of orthotopic HepG-2 liver hepatocellular carcinoma from animal to clinical: (2S,4R)4-[18F]fluoroglutamine PET holds advantages H. Zhu1, X. Xu1, N. Zhou1, Y. Zhang2, T. Liu1, X. Guo1, J. Yang1, F. Wang1, N. Li1, L. Zhu2,3, H. F. Kung3,4, Z. Yang1 1Peking University Cancer Hospital & Institute, China; 2Beijing Normal University, China; 3Capital Medical University, China; 4University of Pennsylvania, USA
S 430
P-272
Nivolumab-DTPA as platform for PD-1 expression probe for precise diagnosis of colon cancer D. Li, X. Li, Z. Shi, Y. Peng, L. Zhang, W. Su, C. Zuo University of Arizona, USA
S 431
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S142: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-273
Development of 99mTc-labeled trivalent isonitrile radiotracer for folate receptor targeted imaging N. A. Lodhi1, J. Y. Park1, K. Kim1, M. K. Hong1, Y. J. Kim1, Y. Lee2, G. J. Cheon1, J. M. Jeong2 1College of Medicine, Seoul National University, Republic of Korea; 2Seoul National University Hospital, Republic of Korea
S 432
P-274
A pretargeted imaging strategy for immune checkpoint ligand PD-L1 expression in tumor based on bioorthogonal Diels-Alder click chemistry L. Qiu2, Q. Lin, Z. Si3, H. Tan, W. Mao, J. Zhou, D. Cheng1, H. Shi1 1Zhongshan Hospital, China; 2Fudan University, China; 3BC Cancer Research Centre, Canada
S 433
P-275
Monitoring the response of PD-L1 expression to EGFR-TKIs in NSCLC xenografts by immuno-PET imaging D. Li
S 435
P-276
An improved integrin alpha 6-targeted SPECT imaging probe for tumor detection Q. Luo1, H. Gao2, S. Du2, C. Luo2, G. Yang2, J. Shi2, B. Jia2, F. Wang1,2 1Institute of Biophysics, CAS, China; 2Peking University, China
S 435
P-277
Synthesis and radiolabeling of a novel glutamine derivative: (2S,4S)4-[18F]FEBGln Y. Huang1, S. Liu1, R. Wu1, L. Zhang2, Y. Zhang2, H. Hong2, A. Zhang2, H. Xiao1, Y. Liu1, Z. Wu1, L. Zhu3, H. Kung4 1Beijing Institute of Brain Disorders, Capital Medical University, China; 2College of Chemistry, Beijing Normal University, China; 3Beijing Normal University, China; 4University of Pennsylvania, USA
S 436
P-278 P-279
Abstract withdrawn The prognostic value of 18F-FDG PET/CT textural features in patients with primary gastric diffuse large B cell lymphoma (PG-DLBCL) Y. Zhou
P-280
New, potent PSMA-inhibitors using squaric acid for coupling and increased affinity L. Greifenstein1, N. Engelbogen, R. Bergmann2, F. Roesch3 1Institute of Nuclear Chemistry, Johannes Gutenberg University Mainz, Germany; 2Helmholtz-Zentrum Dresden-Rossendorf, Germany; 3Johannes Gutenberg University Mainz, Germany
S 440
P-281
Synthesis and evaluation of [18F]fluoropivalic acid as PET imaging biomarker in HCC F. F. Yong1, S. Khanapur1, P. Cheng1, M. Ng1, B. Ramasamy1, J. Goggi1, E. Robins2 1Singapore Bioimaging Consortium, A*STAR, Singapore; 2Singapore Bioimaging Consortium, Singapore
S 440
P-282
Discovery of [18F]JK-PSMA-7 as PET-probe suitable for imaging of small PSMA expressing lesions B. Zlatopolskiy1, H. Endepols1, P. Krapf2, M. Guliyev3, E. Urusova2, R. Richarz2, M. Hohberg4, M. Dietlein4, A. Drzezga4, B. Neumaier5 1Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany; 2Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Germany; 3Herr, Germany; 4Department of Nuclear Medicine, University Hospital of Cologne, Germany; 5Forschungszentrum Jülich GmbH, Germany
S 442
P-283
Imaging-guided anti-PD-L1 immunotherapy with SPECT/CT of 99mTc-labeled nanobody Y. Wu1, H. Gao2, T. Liu1, B. Hu1, X. Zhang3, Y. Wan4, J. Shi5, B. Jia2, F. Wang2 1Medical Isotopes Research left and Department of Radiation Medicine, Peking University, China; 2Peking University, China; 3Medical Isotopes Research left and Department of Radiation Medicine, China; 4CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, China; 5Institute of Biophysics, CAS, China
S 443
P-284
Multimodality hypoxia imaging using positron emission tomography (PET) and multispectral optoacoustic tomography (MSOT): A comparative study X. Deng1, F. F. Yong1, S. Khanapur1, P. Sadasivam1, G. Balasundaram1, J. Song2, J. Goggi1, M. Olivo1, E. Robins3 1Singapore Bioimaging Consortium, A*STAR, Singapore; 2School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore; 3Singapore Bioimaging Consortium, Singapore
S 445
P-285
18F-Radiolabeling
and preliminary preclinical evaluation of an HSP90 ligand P. Nordeman1, J. Patel, E. Briard2, M. Larhed3, G. Antoni1, M. R. Jensen4, B. Skogseid5, A. Monazzam1 1Uppsala University Hospital, Sweden; 2Novartis Pharma AG, Switzerland; 3Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden; 4Novartis Institutes for BioMedical Research, Switzerland; 5Department of Medical Sciences, Endocrine Tumorbiology, Sweden
S 446
P-286
Gold nanoclusters integrated with 64Cu for CCR2 positron emission imaging of triple negative breast cancer D. Sultan1, L. Detering3, Y. Zhao, H. Luehmann3, Y. Liu2 1Washington University School of Medicine, United States; 2Washington University, United States; 3Washington University in St. Louis, USA
S 447
P-287
Synthesis and evaluation of radiogallium labeled ADAM8-activatable cell penetrating peptides for diagnosis of pancreatic cancer T. Fuchigami, R. Yamaguchi, S. Yoshida, M. Nakayama Nagasaki University, Japan
S 448
P-288
Evaluation of targeting and distribution pattern of trastuzumab biosimilar using radioiodine labeling method M. Seo1, B. S. Kim1, W. S. Chung1, H. Park2, H. K. Jun3, J. Kim, M. H. Jung3, K. I. Kim1, J. H. Kang1 1Korea Institute of Radiological and Medical Sciences, Republic of Korea; 2Kirams, Republic of Korea; 3Celltrion, Inc, Republic of Korea PET Molecular targets and near-infrared fluorescence imaging of liver tumor-initiating cells X. Guo Peking University, Beijing, China
S 450
P-289
S 439
S 450
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S143
P-290
A novel 99mTc-labeled molecular probe for PD-L1 detection X. Xu Fudan University Shanghai Cancer Center
S 451
P-291
11C-labeled pictilisib as a novel molecular tracer targeting phosphatidylinositol 3-kinase for breast cancer imaging
S 452
Y. Gai, N. Han, X. Lan Department of Nuclear Medicine,Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, China P-292
Biotin modified red blood cell membrane based nanoparticles: Biomimetic nano-platform for avoiding immune barriers of in vivo system J. Y. Lee1, C. Vyas, P. S. Choi, M. G. Hur2, S. D. Yang1, Y. B. Kong, E. J. Lee, H. S. Song, J. H. Park1 1Korea Atomic Energy Research Institute, Republic of Korea; 2KAERI, Republic of Korea
S 453
P-293
[55Co]Co-DOTATATE improves PET imaging contrast of somatostatin receptor expressing tumours: Comparison with [64Cu]Cu-DOTATATE and [68Ga]Ga-DOTATATE H. Thisgaard1, T. Andersen2, C. Baun1, J. Dam3, B. Olsen1 1Department of Nuclear Medicine, Odense University Hospital, Denmark; 2Department of Nuclear MedicineOdense University Hospital, Odense, Denmark; 3Odense Universitetshospital, Denmark
S 454
P-294
EGFR-TK imaging by technetium-99m labeled complex bearing a quinazoline pharmacophore Z. Si1,2,3, Y. Xiu1,2,3, H. Shi1,2,3, D. Cheng1,2,3 1Department of Nuclear Medicine, Odense University Hospital, Denmark; 2Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark; 3Odense Universitetshospital, Denmark
S 455
P-295
Site-specifically radiolabelled human PD-L1 nanobody: A new tool for clinical PET imaging J. Bridoux1, K. Broos2, M. Crauwels3, Q. Lecocq2, C. Martin4, F. Cleeren5, G. Bormans6, S. Ballet4, G. Raes7, K. Breckpot2, S. Muyldermans3, N. Devoogdt1, V. Caveliers8, M. Keyaerts9, C. Xavier10 1In Vivo Cellular and Molecular Imaging (ICMI), Vrije Universiteit Brussel (VUB), Belgium; 2Laboratory of Molecular and Cellular Therapy (LMCT), VUB, Belgium; 3Cellular and Molecular Immunology (CMIM), VUB, Belgium; 4Research group of Organic Chemistry (ORGC), VUB, Belgium; 5Radiopharmaceutical Research, Department of Pharmacy and Pharmacology, University of Leuven, Belgium; 6KU Leuven, Belgium; 7Myeloid Cell Immunology Lab, VIB Inflammation Research Center, Belgium; 8UZ Brussel, Belgium; 9Nuclear Medicine Department, UZ Brussel, Belgium; 10Vrije Universiteit Brussel, Belgium
S 456
P-296
Sultone-based radiochemistry for the development of 18F-radiotracers for high performance hypoxia PET imaging C. Perrio Cyceron
S 457
P-297
68Ga and MMAF dual-labelled single-chain variable fragments (scFv) for PET imaging of HER2 overexpressed tumors
S 458
R. Fu1, M. Braga2, L. Carroll, I. Stamati3, G. Yahioglu3, E. Aboagye1, P. Miller1 1Imperial College London, United Kingdom; 2Imperial College, United Kingdom; 3Antikor Biopharma, United Kingdom P-298
Fluorine-18 pretargeted PET imaging of cetuximab antibody via in vivo sydnone-alkyne click reaction M. Richard1, C. Truillet2, V. L. Tran2, H. Liu3, M. Roche4, D. Audisio5, B. Kuhnast1, F. Taran5, S. Specklin1 1Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 2Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris-Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, France; 3Service de Chimie Bio-organique et de Marquage CEA-DRF-JOLIOT-SCBM, Université Paris-Saclay 91191, France; 4Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris-Sud, Université Paris-Saclay, Service Hospitalier Frédéric Joliot, Orsay, France; 5Service de Chimie Bio-organique et de Marquage CEA-DRF-JOLIOT-SCBM, Université Paris-Saclay, France
S 459
P-299
Carbon-11 labeled methotrexate derivatives for tumor imaging M. Papachristou1, Z. Zhong2,3, E. Ouchi2, I. Datseris1, P. Scott2, X. Shao2 1Athens General Hospital, Greece; 2The University of Michigan, United States; 3Nankai University, China
S 461
P-300
Screening His-tagged nanobodies by 99mTc(CO)3(H2O)3-Radiolabeling and SPECT/CT for Her2-positive cancer molecular imaging in vivo H. Song1,2, W. Lian1, Q. Shi1, M. Wang2 1Fudan University, China; 2Shanghai Normal University, China
S 462
P-301
A general cGMP-compliant protocol for facile synthesis of fluorine-18 labeled FLT and FMISO W. Qu1, N. Waterhouse2, M. Dooley2, J. Babich2 1Citigroup of Biomedical Imaging Center and Department of Radiology, Weill Cornell Medicine, United States; 2Citigroup of Biomedical Imaging Center, Weill Cornell Medicine, United States
S 463
P-302
A 99mTc-labeled cyclic peptide for integrin αvβ6-targeted SPECT/CT imaging of tumor and pulmonary fibrosis in preclinical mouse models X. Feng, H. Liu, L. Gao, J. Shi, B. Jia, Z. Liu, F. Wang Peking University Health Science Center, China
S 464
P-303
Comparison of [18F]DMFB and [18F]DMPY2 for PET imaging of melanoma A. Pyo, Y. Jung, D. Kim, J. J. Min Chonnam National University Hwasun Hospital Department of Nuclear Medicine, Republic of Korea
S 465
P-304
68Ga-labeled
S 466
non-blocking nanobody for targeting PET imaging of tumor PD-L1 expression G. Lv, L. Qiu, K. Li, Q. Liu, J. Lin Jiangsu Institute of Nuclear Medicine, China
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S144: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-305
Preparation, evaluation, and SPECT/CT imaging of 99mTc-radiolabeled nanobody for Her2-positive breast cancer H. Song1,2, W. Lian1, Q. Shi1, M. Wang1 1Fudan University, China; 2Shanghai Normal University, China
S 467
P-306
Novel 99mTc labelled nitroimidazole xanthates as potential tumor hypoxia imaging agents Q. Ruan1, J. Zhang1, X. Zhang1,2 1Beijing Normal University, China; 2China Institute of Atomic Energy, China
S 468
P-307
Optimizing the molecular design of 68Ga-labeled affibody molecules for in vivo PET imaging of HER3 expression S. Rinne1, B. Mitran1, J. Gentry, A. Vorobyeva1, C. D. Leitao2, K. Andersson2, J. Lofblom2, V. Tolmachev1, A. Orlova1 1Uppsala University, Sweden; 2KTH Royal Institute of Technology, Sweden
S 468
P-308
Synthesis and evaluation of a 99mTc-labelled glucose derivative for tumor imaging X. Zhang, Y. Li1, R. Jing, Y. Li, Q. Ruan1, J. Du2, J. Zhang1 1Beijing Normal University, China; 2China Isotope Corporation, China
S 470
P-309
Caspase-3 activity-based PET probes for assessment of early response to cancer therapy F. Elvas1, A. Solania2, P. Van der Veken3, K. Augustyns3, S. Staelens4, S. Stroobants, D. Wolan2, L. Wyffels5 1University of Antwerp, Belgium; 2Departments of Molecular and Experimental Medicine and Chemical Physiology, The Scripps Research Institute, United States; 3Laboratory of Medicinal ChemistryUniversity of Antwerp, Antwerp, Belgium; 4Molecular Imaging Center AntwerpUniversity of Antwerp, Antwerp, Belgium; 5University Hospital Antwerp, Belgium
S 471
P-310
89Zr-immuno-PET and biodistribution preclinical studies to compare the tumor targeting of the novel anti-CD166 probody drug conjugate CX-2009 and its parental derivatives in a lung cancer xenograft mouse model. M. Chomet1, M. Schreurs2, O. Vasiljeva3, M. Nguyen3, G. van Dongen4, D. Vugts5 1Amsterdam UMC, VU University, Radiology and Nuclear Medicine, Netherlands; 2Amsterdam UMC, Netherlands; 3CytomX Therapeutics Inc., United States; 4VU University Medical center, Netherlands; 5Amsterdam UMC, VU University, Netherlands
S 472
P-311
Bispecific GRPR-PSMA radiotracers for prostate cancers A. Abouzayed1, C. Yim2, B. Mitran1, S. Rinne1, M. Larhed3, V. Tolmachev1, U. Rosenström1, A. Orlova1 1Uppsala University, Sweden; 2Turku PET Centre, Finland; 3Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden
S 473
P-312
Abstract withdrawn
P-313
Synthesis and biological evaluation of a furin-activatable molecular probe for PET imaging of breast cancer L. Qiu, Q. Liu, K. Li, G. Lv, J. Lin Jiangsu Institute of Nuclear Medicine, China
S 475
P-314
A novel 68Ga labeled peptide conjugate for potential use in imaging of HER2-positive breast cancer F. Gao, W. Tao Department of Medical Imaging, Jinling Hospital, China
S 476
P-315
Direct-labeling of iron oxide nanoparticles with zirconium-89 and its biological application in targeting of cancer cells P. S. Choi2, J. Y. Lee1, C. Vyas1, Y. B. Kong2, E. J. Lee2, H. S. Song2, S. D. Yang1, M. G. Hur2, J. H. Park1 1Korea Atomic Energy Research Institute, Korea, Republic of; 2KAERI, Korea, Republic of
S 476
P-316
Radiolabelling and preliminary evaluation of 89Zr-DFO-denosumab, a novel antibody-based radiopharmaceutical or imaging the receptor activator of the nuclear factor k B ligand (RANKL) in the tumour microenvironment. J. Dewulf1, F. Elvas2, T. van den Wyngaert2 1Antwerp University Hospital, Belgium; 2University of Antwerp, Belgium
S 477
P-317
Preparation of 68Ga-labeled carbonic anhydrase IX (CAIX) ligands via CBT/1,2-aminothiol click reaction for tumor hypoxia imaging K. Chen1, Y. Seimbille1,2 1Erasmus MC, Department of Radiology & Nuclear Medicine, Netherlands; 2TRIUMF, Canada
S 479
P-318
Pre-clinical evaluation of a novel [18F]-labeled d-TCO amide derivative for bioorthogonal pretargeted imaging of cancer E. Ruivo1, F. Elvas1, C. Vangestel2, F. Sobott3, S. Staelens2, S. Stroobants1, P. Van der Veken4, L. Wyffels5, K. Augustyns4 1University of Antwerp, Belgium; 2Molecular Imaging Center AntwerpUniversity of Antwerp, Antwerp, Belgium; 3Biomolecular and Analytical Mass SpectrometryUniversity of Antwerp, Antwerp, Belgium; 4Laboratory of Medicinal ChemistryUniversity of Antwerp, Antwerp, Belgium; 5University Hospital Antwerp, Belgium
S 479
P-319
Fluorine-18 labeling of an anti-HER2 sdAb with 6-fluoronicotinyl moiety via the inverse electron-demand Diels-Alder reaction (IEDDAR) including a renal brush border enzyme-cleavable linker Z. Zhou1, M. Zalutsky2, G. Vaidyanathan2 1Duke University, United States; 2Duke University Medical Center, United States
S 480
P-320
Imaging features and prognosis of peripheral primitive neuroectodermal tumors with 18F-FDG PET/CT imaging X. Niu
S 482
P-321
Synthesis of [89Zr]Zr-DFO-PEG5-Tz and in vivo evaluation of bioorthogonally labeled antibody D. Lumen1, D. Vugts2, P. Lang3, M. Chomet4, M. Verlaan5, R. Vos, A. Windhorst6, A. Airaksinen1 1University of Helsinki, Finland; 2Amsterdam UMC,VU University, Netherlands; 3Chemistry research laboratory, Department of Chemistry, University of Oxford, United Kingdom; 4Amsterdam UMC, VU University, Radiology and Nuclear Medicine, Netherlands; 5Amsterdam UMC, VU UniversityRadiology and Nuclear medicine, Radionuclide Center, De Boelelaan 1085c, Amsterdam, Netherlands; 6VU University Medical Center, Netherlands
S 483
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S145
P-322
Fluorine-18 labeling of a single domain antibody fragment with 2,5-dioxopyrrolidin-1-yl 3-(1-(2-(2-(2-(2-[18F] fluoroethoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-5-(guanidinomethyl)benzoate, an alternative residualizing prosthetic agent. Z. Zhou1, D. McDougald2, N. Devoogdt3, M. Zalutsky2, G. Vaidyanathan2 1Duke University, United States; 2Duke University Medical Center, United States; 3In Vivo Cellular and Molecular Imaging (ICMI), Vrije Universiteit Brussel (VUB), Belgium
S 484
P-323
The value of 18F-FDG PET/CT in the diagnosis of multiple myeloma X. Niu
S 486
P-324
Carbon-11 labeled BLZ945 as PET tracer for Colony Stimulating Factor 1 Receptor imaging in the brain Berend van der Wildt, Z. Miao, J. H. Park, S. Reyes, J. Klockow, B. Shen, F. Chin Stanford University, United States
S 487
P-325
A zirconium-89 labeled star-PEG polymer as a radiotracer for image-guide drug delivery D. Beckford-Vera1, S. Fontaine2, G. Trusz1, T. Huynh1, J. Blecha1, G. Ashley3, D. Santi3, H. VanBrocklin1 1University of California, San Francisco, United States; 2ProLynx LLC, United States; 3ProLynx LCC, United States
S 488
P-326
ImmunoPET imaging of CD146 for orthotopic breast cancer detection L. Kang1, D. Jiang2, D. Ni, Wei3, Engle4, Wang1, W. Cai2 1Peking University First Hospital, China; 2University of Wisconsin-Madison, United States; 3Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 4Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, United States
S 489
P-327
Imaging hypoxia-driven regulation of nucleoside and amino acid transporters in breast cancer D. Krys1, F. Wuest2, M. Wuest2, S. Mattingly3, I. Hamann2 1University of Alberta/Department of Oncology, Canada; 2University of Alberta, Canada; 3Department of Oncology, University of Alberta, Canada
S 491
P-328
Mild and site-specific labeling of peptides using a novel biarsenical imaging probe M. Kondrashov1, S. Svensson2, P. Strom3, C. Halldin4, M. Schou5 1Karolinska Institute, Sweden; 2BioPercept AB, Sweden; Linköping University, Sweden; 3Novandi Chemistry AB, Sweden; 4Karolinska Institutet, Sweden; 5AstraZeneca PET Centre at Karolinska Institutet, Sweden
S 492
P-329
Development of a 89Zr-labelled anti-EGFR and cMET bispecific antibody for PET imaging of triple-negative breast cancer S. Suxia1, A. Cavaliere2, S. Lee3, S. Moores4, Y. Huang5, B. Marquez-Nostra1 1Yale University, United States; 2Department of Radiology and Biomedical Imaging, Yale University, United States; 3Yale School of Medicine, United States; 4Janssen Pharmaceutical Philadelphia, PA, United States; 5PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States
S 493
P-330
[18F]Triacoxib: A novel radiotracer for PET imaging of COX-2 identified through in situ click chemistry. M. Litchfield, M. Wuest, D. Galubrecht, T. McMullen, D. Brindley, F. Wuest University of Alberta, Canada
S 494
P-331
Development of FOXM1 inhibitors as potential theranostic agents: initial steps in the validation of FOXM1 as a positron emission tomography (PET) probe for triple negative-breast cancer detection. D. Perez, S. T. Dakhili, C. Bergman, J. Dufour, M. Wuest, F. Wuest, C. Velazquez-Martinez University of Alberta, Canada
S 495
P-332
Synthesis and in vivo evaluation of metabolic radiotracers (S) and (R) 4-[18F]fluoro-3-hydroxybutyrate S. Mattingly1, M. Wuest2, E. Fine3, R. Schirrmacher4, F. Wuest2 1Department of Oncology, University of Alberta, Canada; 2University of Alberta, Canada; 3Department of Radiology, Albert Einstein College of Medicine, United States; 4Department of Oncology, Division of Oncological ImagingUniversity of Alberta, Edmonton, Canada
S 496
P-333
In vivo evaluation of [11C]osimertinib for PET imaging of tumours expressing mutated EGFR A. Högnäsbacka1, E. Kooijman1, R. Schuit1, M. Chomet2, D. Vugts1, G. van Dongen3, A. Poot1, A. Windhorst1 1Amsterdam UMC, VU University, Netherlands; 2Amsterdam UMC, VU University, Radiology and Nuclear Medicine, Netherlands; 3VU University Medical center, Netherlands
S 497
P-334
Evaluation of tryptophan derivative, [18F]trifluoromethyl-L-tryptophan ([18F]CF3-L-Trp) as PET/MR agent for detection of prostate cancer: Comparison with L-[11C]Methionine ([11C]MET) H. Y. Kim1, J. Y. Lee1, H. Seo, Y. Lee2, J. M. Jeong2 1Seoul National University, Republic of Korea; 2Seoul National University Hospital, Republic of Korea
S 499
P-335
Radiosynthesis, in vitro and in vivo evaluation of [18F]Fluorphenylglutamine and [18F] Fluorbiphenylglutamine as novel ASCT-2 directed tumor tracers. T. Baguet4, J. Verhoeven4, S. D. Lombaerde4, S. Piron4, B. Descamps1, C. Vanhove1, H. Beyzavi2, F. D. Vos3 1IbiTech-MEDISIP-INFINITY, Belgium; 2Department of chemistry and biochemistry/University of Arkansas, United States; 3Laboratory of Radiopharmacy, Belgium; 4Ghent University, Belgium
S 500
P-336
N-Methyl carboxylic acid substituted glutamate-urea-lysine analogues, more hydrophilic PSMA inhibitors with high binding affinity B. S. Lee1, S. Y. Chu1, H. J. Jeong1, W. J. Jung1, H. J. Moon1, M. H. Kim1, J. S. Kim1, Y. J. Lee2, K. C. Lee3, M. H. Kim1, S. M. Lim3, D. Y. Chi4 1FutureChem, Korea, Republic of; 2Korea Institute of Radiological & Medicals Sciences, Korea, Republic of; 3KIRAMS, Korea, Republic of; 4Department of Chemistry, Sogang University, Korea, Republic of
S 502
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S146: Poster P-418
23rd International Symposium on Radiopharmaceutical Sciences
Synthesis and evaluation of [18F]SuPAR for PET Imaging of DNA damage-dependent PARP activity A. J. Shuhendler, B. Shen, L. Cui, Z. Chen, J. Rao, F. T. Chin Department of Radiology, Molecular Imaging Program at Stanford (MIPS), USA
S 502
POSTER CATEGORY: RADIOLABELED COMPOUNDS - ONCOLOGY (THERAPY & THERANOSTICS) P-337
131I-AuNPs-TAT particles target cells nuclei in colon cancer for enhanced radioisotope therapy W. Su1,2,3,4, C. Zuo1,2,3,4 1FutureChem, Korea, Republic of; 2Korea Institute of Radiological & Medicals Sciences, Korea, Republic of; 3KIRAMS, Korea, Republic of; 4Department of Chemistry, Sogang University, Korea, Republic of
S 504
P-338
CD146-targeted, multimodal image-guided photoimmunotherapy of melanoma W. Wei1, D. Jiang2, D. Ni, L. Kang3, J. Engle2, W. Cai2 1Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China; 2University of Wisconsin-Madison, United States; 3Peking University First Hospital, China
S 505
P-339
A novel tracer for GD2-positive neuroblastoma S. Spreckelmeyer, K. Schoenbeck, J. Rogasch, N. Beindorff, H. Lode, J. Schulte, P. Hundsdoerfer, H. Amthauer Charité Berlin—Nuclear Medicine Department—Radiopharmacy, Germany
S 506
P-340
Synthesis of [211At]MABG using remote-controlled synthesizer and quality evaluation M. Aoki1, K. Minegishi2, K. Nishijima1, H. Suzuki3, S. Sasaki4, K. Washiyama1, S. Zhao1, K. Nagatsu5, M. Zhang6, K. Takahashi1 1Fukushima Medical University, Japan; 2National Institutes for Quantum and Radiological Science and Technology (QST), National Institute of Radiological Sciences (NIRS), Japan; 3National Institutes for Quantum and Radiological Science and Technology, National Institute of Radiological Sciences, Japan; 4SHI Accelerator Service Ltd., Japan; 5National Institute of Radiological Sciences, Japan; 6Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
S 507
P-341
[89Zr]ZrDFO-CR011 PET imaging to predict response to an antibody drug conjugate for gpNMB in triple negative breast cancer S. Lee1, A. Cavaliere2, S. Suxia3, X. Xiang4, T. Keler5, S. Michelhaugh6, T. Mulnix7, S. Maher8, R. Carson9, Y. Huang10,11, A. Bothwell8, S. Mittal1, B. Marquez-Nostra3 1Yale School of Medicine, United States; 2Department of Radiology and Biomedical Imaging, Yale University, United States; 3Yale University, United States; 4The First Affiliated Hospital of Sun Yat-Sen University , China; 5Celldex Therapeutics, Inc., United States; 6Wayne State University, United States; 7Yale University PET Center, United States; 8Yale University School of Medicine, United States; 9Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States; 10PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States; 11Wayne State University/Karmanos Cancer Institute, United States
S 508
P-342
Theranostics of Glioma Mice with a novel agent 111In-DOTA-AEK22 Y. Tang1, Z. Liao1, W. Liu1, Y. Li1, Y. Hu1, H. Cai1, H. Ma2, J. Yang1, Y. Yang1, J. Liao1, J. Cai2, N. Liu1 1Sichuan University, China; 2Chengdu New Radiomedicine Technology Co. Ltd., China
S 509
P-343
[58mCo]Co-DOTA-hEGF—A novel ligand for targeted Auger electron therapy of glioblastoma using convection-enhanced delivery V. Laursen1, C. Baun, C. Poulsen2, B. Olsen3, J. Dam4, A. Jensen5, H. Thisgaard3 1Department of Nuclear MedicineOdense University Hospital, Odense, Denmark; 2Department of Urology, Odense University Hospital, Denmark; 3Department of Nuclear Medicine, Odense University Hospital, Denmark; 4Odense Universitetshospital, Denmark; 5DTU Nutech, Technical University of Denmark, Denmark
S 511
P-344
Evans blue attachment prolongs blood half-life and improves radionuclide therapy in a patient-derived xenograft model of pancreatic neuroendocrine tumors L. Zhao1, X. Wen2, Z. Guo2, H. Chen1, Q. Lin1 1The First Affiliated Hospital of Xiamen University, China; 2Xiamen University, China
S 512
P-345
PARaDIM—A PHITS-based Monte Carlo tool for internal dosimetry L. Carter1, T. Crawford2, T. Sato3, T. Furuta3, W. Bolch4, J. Brown4, C. Kim5, C. Choi5, J. Lewis1 1Memorial Sloan Kettering Cancer Center, United States; 2University of Rhode Island, United States; 3Japan Atomic Energy Agency, Japan; 4University of Florida, United States; 5Hanyang University, Korea, Republic of
S 512
P-346
SPECT/CT imaging of chemotherapy-induced tumor apoptosis using 99mTc-labeled dendrimer-entrapped gold nanoparticles Y. Xing
S 514
P-347
PET imaging with [11C]NMS-E973 reveals difference between healthy and malignant expressed HSP90 K. Vermeulen1, M. Ahamed2, G. Bormans1 1KU Leuven, Belgium; 2Centre for Advanced Imaging, The University of Queensland, Australia
S 514
P-348
Second generation of triazolominigastrins: Towards further improvement of tumour-targeting characteristics of radiopeptidomimetics N. Grob1, S. Schmid2, M. Behe, R. Schibli1, T. Mindt3 1ETH Zurich, Switzerland; 2ETH Zurich, Institute of Pharmaceutical Sciences, Switzerland; 3Ludwig Boltzmann Institute Applied Diagnostics, Austria
S 515
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S147
P-349
Radiolabeling and in vitro evaluation of a TA-MUC1 specific monoclonal antibody and its corresponding single chain fragment with zirconium-89, scandium-44, and lutetium-177: Promising tools for diagnosis and therapy of breast cancer B. Klasen1, N. Stergiou2, E. S. Moon3, E. Schmitt2, F. Roesch4 1Institute for Nuclear Chemistry, Johannes Gutenberg-University Mainz, Germany; 2Institute for Immunology, University Medical Center Mainz, Germany; 3Johannes Gutenberg University Mainz, Institute of Nuclear Chemistry, Germany; 4Johannes Gutenberg Univ., Germany
S 517
P-350
Preclinical evaluation of chemokine receptor 4 (CXCR4) as a theranostic target in high-risk neuroblastoma D. Liu, M. Schultz, M. Li, D. Lee, K. Nourmahnad, A. Bellizzi, M. S. O’Dorisio University of iowa, United States
S 518
P-351
Monitoring therapeutic response of lung adenocarcinoma to ZHER2:V2-pemetrexed by SPECT imaging with 99mTc-ZHER2:V2-pemetrexed. J. Han
S 519
P-352
Antibody nanotechnology mediated by site-specific assembly enhances antitumor efficacy of therapeutic antibodies via multivalent binding Y. Zhao1, L. Gao2, F. Wang2, G. Nie1 1National Center for Nanoscience and Technology, China; 2Peking University, China
S 521
P-353
Optimization of 177Lu-labeled GRPR-antagonist PEG2-RM26 for GRPR-targeted radiotherapy: Influence of chelator on labeling, stability, and biodistribution B. Mitran1, S. Rinne1, M. Konijnenberg2, T. Maina3, B. A. Nock, M. Altai1, A. Vorobyeva1, M. Larhed4, 1Uppsala University, Sweden; 2Erasmus MC, Netherlands; 3I/R-RP, NCSR \’Demokritos\’, Greece; 4Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden
S 522
P-354
[68Ga]Ga-ABY-025/PET-CT for individualized management of breast cancer patients: Automated production for multicenter clinical study I. Velikyan1, P. Schweighofer2, P. Feldwisch3, J. Seemann4, F. Frejd3, H. Lindman5, J. Sorensen6 1Department of Medicinal Chemistry, Uppsala University, Sweden; 2Eckert & Ziegler Eurotope GmbH, Germany; 3Affibody AB, Solna, Sweden; 4Eckert & Ziegler Eurotope GmbH, Sweden; 5Department of Immunology, Genetics and Pathology, Uppsala University, Sweden; 6Section of Nuclear Medicine and PET, Department of Surgical Sciences, Uppsala University, Sweden
S 524
P-355
The study of biodistribution and micro-PET imaging of 18F-BPA in nude mice bearing glioma L. Fenglin, L. Zhifu, F. Caiyun, L. Zihua China Institute of Atomic Energy, China
S 525
P-356
[64Cu]CuCl2 PET metallomics for determining the anticancer mechanism of novel drug Dextran-Catechin G. Pascali1, A. Parmar2, F. Voli3, L. Lerra3, E. Lee3, A. Ahmed-Cox3, K. Kimpton3, G. Cirillo4, A. Arthur2, D. Zahra2, G. Rahardjo2, G. Liu1, N. Lengkeek1, P. Pellegrini1, F. Saletta5, A. Charil6, M. Kavallaris3, O. Vittorio3 1ANSTO, Australia; 2The Australian Nuclear Science and Technology Organisation, Australia; 3CCIA, Australia; 4University of Calabria, Italy; 5Westmead Hospital, Australia; 6ANSTO, United States
S 526
P-358
Production and radiochemical purity of 177Lu-PSMA-617 for clinical trial A. Asad1, R. Scharli2, L. Morandeau1, R. Price3 1Sir Charles Gairdner Hospital, Australia; 2University of Western Australia, Australia; 3Sir Charles Gairdner Hospital—Medical Technology & Physics, Australia
S 527
P-359
177Lu-PSMA-I&T PSMA radioligand therapy in metastatic castration-resistant prostate cancer: First clinical trial in Asia T. Bu
S 527
P-360
Experimental study of 68Ga/177Lu-PSMA I&T: A novel PSMA inhibitor for theranostic of prostate cancer L. Zhang1, P. Zhang2, F. Wang 1Nanjing Medical Univesity Affiliated Nanjing First Hospital, China; 2༡ிᕷ➨୍་㝔(༡ி་⛉Ꮫ㝃ᒓ༡ி་㝔), Chile
S 528
POSTER CATEGORY: RADIOLABELED COMPOUNDS - OTHER MEDICAL DISCIPLINES P-361
Development of a PET tracer targeting neutrophil elastase for inflammation imaging P. Nordeman1, M. Elgland1, S. Estrada2, P. Jimenez-Royo3, M. Bergström4, G. Antoni1 1Uppsala University Hospital, Sweden; 2Uppsala University, Sweden; 3GSK, United Kingdom; 4GSK, Sweden
S 529
P-362
Novel imaging of the third gasotransmitter hydrogen sulfide using 99mTc-labeled polyhydroxy acids J. M. Jeong1, Y. J. Kim2, J. Y. Park2, J. Y. Lee3, Y. Lee4 1Seoul National University Hosp, Republic of Korea; 2Seoul National University, College of Medicine, Republic of Korea; 3Seoul National University, Republic of Korea; 4Seoul National University Hospital, Republic of Korea
S 530
P-363
Investigation of the potentials of a thymidine phosphorylase imaging probe for the differential diagnosis of nonalcoholic steatohepatitis K. Higashikawa1, R. Uehara1, S. Horiguchi1, Y. Shibata2, M. Tarisawa1, H. Kitaura3, H. Yasui1, H. Takeda1, Y. Kuge1 1Hokkaido University, Japan; 2Graduate School of Biomedical Science and Engineering, Hokkaido University, Japan; 3Health Sciences University of Hokkaido, Japan
S 532
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S148: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-364
18F-Radiolabeling
and in vivo evaluation of two diverse glycomimetics using PET K. Bratteby1, E. Torkelsson9, E. T. L’Estrade1, K. Peterson2, V. Shalgunov3, M. Xiong1, H. Leffer2, F. Zetterberg4, T. Ohlsson5, N. Gillings6, U. Nilsson2, M. Herth7, M. Erlandsson8 1University of Copenhagen, Denmark; 2Lund University, Sweden; 3Department of Drug Design and Pharmacology, University of Copenhagen, Denmark; 4Galecto Biotech, Sweden; 5University Hospital of Lund, Sweden; 6Copenhagen University Hospital Rigshospitalet, Denmark; 7Univesity of Copenhagen, Sweden; 8Skanes university hospital, Sweden; 9Red Glead Discovery, Sweden
S 533
P-365
Imaging of occult bacterial infection using 68Ga-Yersiniabactin targeting siderophore transport C. Zhai1, M. Petrik2, S. He3, X. Chen4, J. Lu4, M. Ahmadi5, H. Haas6, B. Pfeifer5, C. Decristoforo7 1Southern Medical University, China; 2Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, Czech Republic; 3Department of Nuclear Medicine, Guangdong General Hospital, China; 4School of Forensic Medicine, Southern Medical University, China; 5Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, United States; 6Division of Molecular Biology, Biocenter, Medical University Innsbruck, Austria; 7Medical University Innsbruck, Austria
S 534
P-366
Visualisation of fibrosis after tissue damage with PET—A tracer for the fibroblast activation protein L. Langer, A. Hess, L. Reffert, J. Bankstahl, J. Thackeray, F. Bengel, T. Ross Hannover Medical School, Germany
S 535
P-367
Synthesis and characterization of 9-(4-fluoro-3-(hydroxymethyl)butyl)-2-(phenylthio)-6-oxopurine ([18F]FHBT) as a PET tracer for HSV1-tk reporter gene imaging T. Fuchigami1, T. Haywood2, G. Gowrishankar3, D. Anders4, M. Namavari2, S. Gambhir2 1Nagasaki University, Japan; 2Stanford University, United States; 3Stanford University School of Medicine, United States; 4Stanford Uiversity, United States
S 537
P-368
First-in-class bicyclic peptide based imaging agent targeting for non-invasive diagnosis and monitoring of fibrosis I. Velikyan1, S. Estrada2, R. Selvaraju3, G. van Scharrenburg5, H. Steen5, G. Antoni4 1Department of Medicinal Chemistry, Uppsala University, Sweden; 2Uppsala University, Sweden; 3Preclinical PET-MR Pilot platform, Dept. of Medicinal Chemistry, Uppsala University, Sweden; 4Uppsala University Hospital, Sweden; 5Biorion Technologies
S 538
P-369
Development and preclinical evaluation of an immunoPET tracer for clinical imaging of Aspergillosis A. Maurer1, N. Beziere2, D. Seyfried1, J. Wehrmüller3, P. Spycher3, J. Schwenck4, A. Wild5, G. Davies6, F. Boschetti7, S. Wiehr5, S. Geistlich3, M. Gunzer8, C. Thornton6, R. Schibli9, G. Reischl10, B. Pichler11 1Werner Siemens Imaging Center, Deptartment of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Germany; 2Werner Siemens Imaging Center, Deptartment of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Germany; 3Paul Scherrer Institute, Center for Radiopharmaceutical Sciences, Switzerland; 4Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard Karls University Tuebingen, Germany; 5Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Germany; 6School of Biosciences, College of Life & Environmental Sciences, University of Exeter, United Kingdom; 7Chematech; 8Institute for Experimental Immunology and Imaging, University Hospital, University of Duisburg-Essen, Germany; 9ETH Zurich, Switzerland; 10University Hospital Tuebingen, Germany; 11Werner Siemens Imaging Center, Germany
S 539
P-370
Synthesis of 68Ga-NOTA-insulin a PET probe for insulin imaging M. Pandey1, N. Nelson2, K. Schlasner2, G. Curran2, P. MIn2, T. DeGrado3, K. Kandimalla4, V. Lowe2 1Mayo Clinic, Department of Radiology, United States; 2Mayo Clinic Rochester, United States; 3Mayo Clinic, United States; 4Department of Pharmaceutics, University of Minnesota, United States
S 540
P-371
Early prediction of radiation induced lung fibrosis using Cu-64-labeled 1,4,7-triazacyclononane, 1-glutaric acid-4,7 acetic acid (NODAGA)-galactose-bombesin analogue Y. J. Lee1, H. Ahn2, J. A. Park2, K. C. Lee2, J. Y. Kim3, J. H. Kang4, Y. Lee 1Korea Institute of Radiological & Medicals Sciences, Republic of Korea; 2KIRAMS, Republic of Korea; 3KIRAMS(Korea Institue of Radiological & Medical Sciences), Republic of Korea; 4Korea Institute of Radiological and Medical Sciences, Republic of Korea
P-372
A novel monoacylglycerol lipase-targeted 18F-labeled probe for positron emission tomography imaging of brown adipose tissue in the energy network R. Cheng1, M. Fujinaga2, Z. Chen3, T. Shao3, X. Zhang4, L. Wang5, S. Sun6, C. Ran7, M. Zhang8, S. Liang3 1School of Medical Imaging, Tianjin Medical University, China; 2Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3MGH/Harvard, United States; 4MGH/Harvard, China; 5The first affiliated hospital of Jinan University, China; 6College of Nuclear Technology & Chemistry and Biology, Hubei University of Science and Technology, China; 7Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, United States; 8Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
S 542
S 542
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
23rd International Symposium on Radiopharmaceutical Sciences
Poster: S149
P-373
Synthesis and initial preclinical evaluation of the CRTH2 antagonist [11C]MK-7246 J. Eriksson1, T. Roy2, S. Sawadjoon2, K. Bachmann2, C. Sköld2, M. Larhed3, J. Weis4, R. Selvaraju5, 1Uppsala University Hospital and Department of Medicinal Chemistry, Uppsala University, Sweden; 2Department of Medicinal Chemistry, Uppsala University, Sweden; 3Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden; 4Department of Surgical Sciences, Uppsala University, Sweden; 5Preclinical PET-MR Pilot platform, Dept. of Medicinal Chemistry, Uppsala University, Sweden; 6Department of Immunology, Genetics and Pathology, Uppsala University, Sweden; 7Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
S 544
P-374
Research on the preparation of 99mTc-TPN towards VPAC1 receptor and testing in animals T. Jiang1,2,3,4,5,6,7, L. Zhen1,2,3,4,5,6,7, X. Zhang1,2,3,4,5,6,7, X. Ding1,2,3,4,5,6,7 1Uppsala University Hospital and Department of Medicinal Chemistry, Uppsala University, Sweden; 2Department of Medicinal Chemistry, Uppsala University, Sweden; 3Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden; 4Department of Surgical Sciences, Uppsala University, Sweden; 5Preclinical PET-MR Pilot platform, Dept. of Medicinal Chemistry, Uppsala University, Sweden; 6Department of Immunology, Genetics and Pathology, Uppsala University, Sweden; 7Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
S 545
P-375
Development of a new method for the microbiological analysis of iodine 131 A. Aiboud1, N. Bentaleb2 1National Energy Center of Nuclear Science and Technology of Morocco, Morocco; 2National Energy Center of Nuclear Science and Technology of Morocco, Morocco
S 547
P-376
Evaluation of [18F]NEBIFQUINIDE, a new TSPO PET tracer, in a mouse model of non-alcoholic fatty liver disease N. Berroteran-Infante1, A. Pillinger1, L. Fetty1, M. Hacker1, W. Wadsak2, A. Haug1, M. Mitterhauser2 1Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria; 2Medical University of Vienna, Austria
S 547
P-377
Ex vivo-loaded chylomicron-like particles labelled with 18F-BDP-triglyceride as an imaging agent for brown adipose tissue M. Bauwens1, A. Paulus1, N. Drude2, E. Nascimento3, E. Buhl4, J. Berbee5, P. Rensen5, W. V. M. Lichtenbelt3, F. Mottaghy6 1MUMC, Netherlands; 2Institute for Experimental Molecular Imaging, University Hospital and Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany; 3Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Netherlands; 4Electron Microscopy Facility, University Hospital RWTH, Aachen, Germany; 5Division of Endocrinology, Department of Medicine, Leiden University Medical Center, Netherlands; 6Department of Medical Imaging, Division of Nuclear Medicine, MUMC, Netherlands
S 548
P-378
Targeting bacterial peptidoglycan with 11C-D-alanine and 11C-D-alanyl-D-alanine M. Parker1, B. Schulte1, J. Luu1, T. Huynh2, K. Ibrahim1, S. Jivan3, R. Flavell4, M. Ohliger1, O. Rosenberg1, D. Wilson1 1University of California, San Francisco, United States; 2UCSF Radiology and Biomedical Imaging, United States; 3University of California San Francisco, United States; 4UCSF, United States
S 549
P-379
Optimization of 89Zr-based radiotracers for long-term in vivo cell tracking with PET imaging I. Jonsson, E. Jussing, X. Zhang, L. Lu1, E. Samén, R. Harris, S. Holmin1, T. Tran Karolinska University Hospital, Sweden
S 551
POSTER CATEGORY: RADIOPHARMACOLOGY P-380
Synthesis and radiopharmacological evaluation of three F-18-labeled celecoxib derivatives— A quest to trick metabolism M. Laube1, C. Gassner1, C. Neuber2, M. Bachmann3, T. Kniess2, J. Pietzsch4 1Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany; 2Helmholtz-Zentrum Dresden-Rossendorf, Germany; 3Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 4Department Radiopharmaceutical and Chemical Biology, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany
S 552
P-381
Radioiodinated 4-(p-iodophenyl)butyric acid as a versatile agent for in vivo imaging with SPECT X. Wen1, L. Zhao2, H. Chen2, Z. Guo1, X. Zhang1 1Xiamen University, China; 2The First Affiliated Hospital of Xiamen University, China
S 553
P-382
Evaluation of [18F]DBT10 as potential α7 nAChRs diagnostic biomarker for PET imaging of stroke-associated neuroinflammation in a sheep stroke model R. Teodoro1, B. Nitzsche2, W. Härtig2, B. Wenzel, M. Scheunemann, S. Aleithe, J. Luthardt, M. Rullmann, G. Becker, T. Grunwald, D. Michalski, J. Boltze, O. Sabri, P. Brust3, M. Patt, W. Deuther-Conrad, H. Barthel 1Helmholtz-Zentrum Dresden Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 2Nuklearmedizin, Universität Leipzig, Germany; 3Helmholtz-Zentrum Dresden-Rossendorf, Germany
S 554
P-383
Evaluation of potential cleavable linkers for reduction of renal accumulation of radiolabeled peptides and antibody fragments using mouse renal brush border membranes F. Cleeren1, T. Thibangu2, C. Deroose2, G. Bormans2 1Radiopharmaceutical Research, Department of Pharmacy and Pharmacology, University of Leuven, Belgium; 2KU, Leuven, Belgium
J Label Compd Radiopharm 2019: 62 (Suppl. 1): S123–S588
S 555
S150: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-384
Structure-based design of novel squaric acid coupled KuE targeting vectors with PSMA and first in vitro evaluation studies H. Lahnif1, L. Greifenstein2, T. Grus2, C. Kersten3, R. Bergmann4, F. Roesch5 1Johannes Gutenberg - University Mainz Institute of Nuclear Chemistry, Germany; 2Institute of Nuclear Chemistry, Johannes Gutenberg University Mainz, Germany; 3Institute of Pharmacy and Biochemistry - Therapeutical Life Sciences, Johannes Gutenberg University Mainz, Germany; 4Helmholtz-Zentrum Dresden-Rossendorf, Germany; 5Johannes Gutenberg University, Germany
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P-385
Structure-based design of a new CXCR4 targeting peptidomimetic molecule for potential PET imaging M. K. Sarvestani1, M. Schaefer2, A. Carlesso3, S. Stadlbauer2, L. Eriksson3, K. Kopka4 1German Cancer Research Center (DKFZ), Germany; 2German Cancer Research Center, Germany; 3University of Gothenburg, Sweden; 4German Cancer Research Centre (dkfz), Germany
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P-386
Bioequivalence study of 68Ga radiolabeling DOTA-iNGR kit S. Wang
S 558
P-387
Evaluation of bivalent peptides as radioligands for peptide receptor radionuclide therapy of prostate cancer N. Romantini1, S. Dobitz2, S. Alam1, M. Spillmann1, R. Schibli2, X. Deupi1, H. Wennemers2, P. Berger1, M. Behe1 1Paul Scherrer Institute, Switzerland; 2ETH, Zurich, Switzerland
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POSTER CATEGORY: TARGETRY P-388
Separation study of silver radionuclides from a palladium target irradiated by cyclotron T. Ohya1, K. Nagatsu2, K. Minegishi1, M. Hanyu1, M. Zhang3 1National Institutes for Quantum and Radiological Science and Technology (QST), National Institute of Radiological Sciences (NIRS), Japan; 2National Institute of Radiological Sciences, Japan; 3Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
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P-389
Preliminary evaluation of the enriched zinc-68 chloride solution target for the continuous production of gallium-68 chloride on a medical cyclotron K. M. Nielsen, M. Jensen, K. Pedersen, F. Zhuravlev Center for Nuclear Technologies, Technical Univeristy of Denmark, Denmark
S 560
P-390
Radiochemical separation/purification for establishing a 44Ti/44Sc generator S. Huclier1, D. Medvedev2, C. Cutler2 1Subatech and Arronax, France; 2Brookhaven National Laboratory, USA
S 562
P-391
Cyclotron production of 47Ca for 47Ca/47Sc generator R. Walczak1, R. Misiak2, M. Pruszynski1, M. Agnieszka1, M. Sitarz, J. Jastrzębski, A. Bilewicz1 1Institute of Nuclear Chemistry and Technology, Poland; 2The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences, Poland
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P-392
Production and application therapeutic radionuclides at TRIUMF: Auger emitters V. Radchenko1, T. Kostelnik2, J. Mynerich1, J. Engle3, Aeli Olson4, I. Kalomista5, A. Marinova6, E. Kurakina6, C. Ramogida7, C. Hoehr1, P. Kunz8, J. Lassen8, M. Sakheie9, S. Zeisler1, A. Robertson10, L. L. L. Li11, D. Prevost12, L. Graham12, D. Filosofov6, C. Orvig13, P. Schaffer1 1TRIUMF, Canada; 2Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, BC, Canada; 3Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, United States; 4Department of Medical Physics, University of Wisconsin, Highland Avenue, United States; 5Department of Chemistry, University of Copenhagen, Denmark; 6DLNP, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980, Dubna, Moscow Region, Russian Federation, Russian Federation; 7Simon Fraser University & TRIUMF, Canada; 8Accelerator Division, TRIUMF, Canada; 9Life Science Division, TRIUMF, Canada; 10Life Sciences Division, TRIUMF, Vancouver BC, Canada; 11The University of British Columbia, Canada; 12Life Sciences Division, TRIUMF, Canada; 13University of British Columbia, Canada
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P-393
Automated production of Ga-68 chloride and Ga-68-dotatate on a low energy medical cyclotron W. Tieu1, C. Hollis1, K. Kuan1, M. Malinconico2, P. Takhar1 1Molecular Imaging and Therapeutic Research Unit, South Australian Health and Research Institute, Australia; 2COMECER S.p.A., Castel Bolognese, Italy
S 565
P-394
Production, quality control of next-generation PET nuclide zirconium-89 (89Zr) F. Wang1,2, Z. Yang1,2, H. Zhu1,2 1Molecular Imaging and Therapeutic Research Unit, South Australian Health and Research Institute, Australia; 2COMECER S.p.A., Castel Bolognese, Italy
S 565
P-395
First experience on producing gallium-68 with liquid target at HUS Medical Imaging Center using a Cyclone KIUBE 180 cyclotron T. Koivula, J. Lehto, T. Lipponen, J. Laine, J. Tervonen, K. Bergström Medical Imaging Center, Cyclotron Unit, HUS Helsinki University Hospital, Finland
S 566
P-396
Automated production of Cu-64, Zr-89, Ga-68, Ti-45, I-123, and I-124 with a medical cyclotron, using a commercial solid target system M. Malinconico1, J. Asp2, K. Kuan2, W. Tieu2, C. Lang2, G. Guidi1, F. Boschi1, P. Takhar2 1COMECER S.p.A., Castel Bolognese, Italy; 2Molecular Imaging and Therapy Research Unit, South Australian Medical Research Institute, Adelaide, Australia
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23rd International Symposium on Radiopharmaceutical Sciences
Poster: S151
P-397
Shortage of Ge-68/Ga-68 generators—Incoming material inspection and GMP compliant use of non-approved generators D. Mueller, A. Fuchs, Y. Leshch, M. Proehl Zentralklinik Bad Berka GmbH, Germany
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P-398
Chromatographic separation methods for nuclear medicine radioisotopes D. McAlister, E. P. Horwitz Eichrom Technologies, LLC, USA
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P-399
Initial results of cyclotron produced Ga-68 and their post-processing using solid targets D. Mueller, M. Schlitter, S. Senftleben, M. Proehl, Y. Leshch, A. Fuchs Zentralklinik Bad Berka GmbH, Germany
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P-400
Evaluation of cyclotron produced 43,44,47Sc from titanium(0) and titanium oxide C. Loveless1, T. Carzaniga2, J. Blanco1, S. Braccini2, S. Lapi1 1University of Alabama at Birmingham, USA; 2Albert Einstein Center for Fundamental Physics, Universität Bern, Switzerland
S 569
P-401
Isolation of 99mTc from the gamma irradiated 100Mo target M. Gumiela, P. Kozminski, A. Bilewicz Institue of Nuclear Chemistry and Technology, Poland
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P-402
Scandium-47 separation by extraction chromatography using TBP resin R. Mikolajczak, D. Pawlak, W. Wojdowska, I. Cieszykowska, M. Zoltowska, J. Parus National Centre for Nuclear Research Radioisotope Centre POLATOM, Poland
S 571
P-403
Cyclotron production of scandium-44 from enriched calcium-44 targets W. Wojdowska, D. Pawlak, I. Cieszykowska, M. Zoltowska, T. Janiak, T. Barcikowski, J. Parus, R. Mikolajczak National Centre for Nuclear Research Radioisotope Centre POLATOM, Poland
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POSTER CATEGORY: MISCELLANEOUS P-404
Preintervention and postintervention air quality monitoring in a low-income radiopharmacy F. Ekoume1, H. Boersma2, S. Rubow3 1Yaounde General Hospital and Stellenbosch University, Cameroon; 2UMCG, Netherlands; 3Stellenbosch University, South Africa
S 573
P-405
HILIC—A simple HPLC method to determine [18F]fluoride in plasma and tissue samples B. Wenzel1, R. Moldovan2, R. Teodoro2, W. Deuther-Conrad, P. Brust1 1Helmholtz-Zentrum Dresden-Rossendorf, Germany; 2Helmholtz-Zentrum Dresden Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany
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P-406
Implementation of a quality management system: Self-assessments in a sub-Saharan radiopharmacy F. Ekoume1, H. Boersma2, S. Rubow3 1Yaounde General Hospital and Stellenbosch University, Cameroon; 2UMCG, Netherlands; 3Stellenbosch University, South Africa
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P-407
Radiopharmaceutical production technology at the Nuclear Medicine Centre Federal Siberian Research Clinical Centre, Russia A. Ozerskaya1, K. Belugin1, N. Tokarev1, N. Chanchikova1, M. Larkina2, E. Podrezova3, M. Yusubov4, M. Belousov2 1Federal Siberian Research Clinical Centre, FMBA of Russia, Russian Federation; 2Siberian State Medical University, Russian Federation; 3National Research Tomsk Polytechnic University, Russian Federation; 4Siberian State Medical University, National Research Tomsk Polytechnic University, Russian Federation
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P-408
Albendazole ameliorates triple-negative breast cancer by inhibiting glucose uptake pathway H. Liu, H. Sun, B. Zhang, S. Liu, S. Deng, Z. Weng, B. Zuo, J. Yang, Y. He First Affiliated Hospital of Soochow University, China
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P-409
21 Code of Federal Regulation Part 11, Electronic Records: Electronic signatures, scope and application for the commercial PET manufacturing world in the USA M. Haka, A. Anzellotti, C. Buchanan, A. Aksanov, M. Nazerias, E. Webster PETNET Solutions, USA
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P-410
Measurement of the metal impurity in PET probe using the HPLC post-column method M. Hanyu1, H. Ishii2, N. Nengaki3, M. Ogawa3, D. Arashi4, K. Furutsuka3, H. Hashimoto5, K. Kawamura6, M. Zhang7 1National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Japan; 2Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3SHI Accelerator Service, Japan; 4Tokyo Nuclear Services, Japan; 5National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Japan; 6National Institute of Radiological Sciences, National Institute for Quantum and Radiological Science and Technology, Japan; 7Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
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P-411
Study of the radioactive contaminants appearing during [18F]FDG production T. Tasi, R. Ay, G. Tihanyi, B. Bojtor, Z. Ancsan, P. Mikecz Kaposi Mór Teaching Hospital, Medicopus Nonprofit Ltd., Hungary
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S152: Poster
23rd International Symposium on Radiopharmaceutical Sciences
P-412
Rapid analysis of chemical purity in 68Ga-PSMA-11 and 68Ga-DOTA-NOC by capillary electrophoresis D. Antuganov, Y. Antuganova, T. Zykova Almazov National Medical Research Centre, Russian Federation
S 582
P-413
Simultaneous analysis of seven potentially toxic chemical impurities in the radiopharmaceuticals formulations by capillary electrophoresis D. Antuganov1, Y. Antuganova1, T. Zykova1, R. Krasikova2 1Almazov National Medical Research Centre, Russian Federation; 2N.P. Bechtereva Institute of Human Brain, Russian Academy of Sciences, Russian Federation
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P-414
Use of [11C]CO2 to study molecular organic frameworks adsorption performance G. Perkins1, P. Southon2, C. Kepert2, G. Pascali1 1ANSTO, Australia; 2University of Sydney, Australia
S 584
P-415
Application of BODIPY650/665 for optical imaging of prostate cancer S. Son1,2, K. Kim1,2, H. Kwon1,2, D. Choi1,2, I. Minn1,2, Y. Byun1 1ANSTO, Australia; 2University of Sydney, Australia
S 585
P-416
A simple spot test for semi-quantitative determination of tetrabutylammonium in [18F] PSMA-1007 N. Halvorsen, O. H. Kvernenes Center for nucl.med/PET, Haukeland University Hospital, Norway
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P-417
Validation of [18F]PSMA-1007—Does synthesis platform matter? T. C. Adamsen1, N. Halvorsen2 1Haukeland University Hospital, Norway; 2Center for nucl.med/PET, Haukeland University Hospital, Norway
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Abstracts-Poster
DOI: 10.1002/jlcr.3725
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Poster Presentations 23rd International Symposium on R a d i o p h a rm a c e u t i c a l Sc i e n c e s Poster Cate gory: Radiochemistry ‐ 18 F P-001 | Synthesis and initial in vitro characterization of [18F]fluoroalkyl derivatives of GSK1482160 as new candidate P2X7R radioligands Mingzhang Gao; Min Wang; Barbara Glick‐Wilson; Jill Meyer; Jonathan Peters; Paul Territo; Mark Green; Gary Hutchins; Hamideh Zarrinmayeh; Qi‐Huang Zheng Indiana University School of Medicine, United States
Objectives The purinergic receptor P2X ligand‐gated ion channel type 7 (P2X7R) is an adenosine triphosphate (ATP)‐gated ion‐ channel, and P2X7R is a key player in inflammation. P2X7R is an emerging therapeutic target in central nervous system (CNS) diseases including Alzheimer's disease (AD) and Parkinson's disease (PD), because P2X7R also plays a pivotal role in neuroinflammation. P2X7R represents a potential molecular imaging target for neuroinflammation via biomedical imaging technique positron emission tomography (PET), and several radioligands targeting P2X7R have been developed and evaluated in animals. In our previous work, we have developed and characterized [11C]GSK1482160 as a P2X7R radioligand for neuroinflammation,1,2 clinical evaluation of [11C]GSK1482160 in healthy controls and patients is currently underway, and the estimation of radiation dosimetry for [11C] GSK1482160 in normal human subjects has been reported.3 Since the half‐life (t1/2) of radionuclide carbon‐ 11 is only 20.4 min, it is attractive for us to develop derivatives of [11C]GSK1482160, which can be labeled with the radionuclide fluorine‐18 (t1/2, 109.7 min), and a fluorine‐ 18 ligand would be ideal for widespread use.4 To this end, a series of [18F]fluoroalkyl including [18F]fluoromethyl (FM), [18F]fluoroethyl (FE), and [18F]fluoropropyl (FP)
derivatives of GSK1482160 have been prepared and examined as new potential P2X7R radioligands. Methods The reference standards (S)‐N‐(2‐chloro‐3‐(trifluoromethyl)benzyl)‐1‐(2‐fluoromethyl)‐5‐oxopyrrolidine‐2‐ carboxamide (IUR‐1600 or FM‐GSK1482160), (S)‐N‐(2‐ chloro‐3‐(trifluoromethyl)benzyl)‐1‐(2‐fluoroethyl)‐5‐ oxopyrrolidine‐2‐carboxamide (IUR‐1601 or FE‐ GSK1482160), and (S)‐N‐(2‐chloro‐3‐(trifluoromethyl) benzyl)‐1‐(2‐fluoropropyl)‐5‐oxopyrrolidine‐2‐ carboxamide (IUR‐1602 or FP‐GSK1482160) were synthesized either from tert‐butyl (S)‐5‐oxopyrrolidine‐2‐carboxylate, fluoroalkyl building blocks 5, and 2‐chloro‐ 3‐(trifluoromethyl)benzylamine in three steps or from desmethyl‐GSK1482160 and fluoroalkyl building blocks in one step. Their corresponding precursors for fluorine‐ 18 labeling were synthesized in similar methods. The target tracers (S)‐N‐(2‐chloro‐3‐(trifluoromethyl)benzyl)‐1‐ (2‐[18F]fluoroethyl)‐5‐oxopyrrolidine‐2‐carboxamide ([18F]IUR‐1601 or [18F]FE‐GSK1482160) and (S)‐N‐(2‐ chloro‐3‐(trifluoromethyl)benzyl)‐1‐(2‐[18F]fluoropropyl)‐ 5‐oxopyrrolidine‐2‐carboxamide ([18F]IUR‐1602 or [18F] FP‐GSK1482160) were synthesized either from their chloro‐precursors and K[18F]F/Kryptofix 2.2.2 in one step or from desmethyl‐GSK1482160 and [18F]fluoroalkyl tosylates in two steps. The receptor affinity of fluoroalkyl derivatives of GSK1482160 was determined by a radioligand competitive binding assay using [11C] GSK1482160. Results We failed to synthesize IUR‐1600, because the fluoromethylated compound synthesized by the reaction of amide with fluoromethyl halides or sulfonates were too unstable to be detected or purified from the reaction mixtures.6 Instead, desmethyl‐GSK1482160 reacted with FCH2OTs/KOH to yield a spiral compound, (S)‐2‐(2‐ chloro‐3‐(trifluoromethyl)benzyl)tetrahydro‐1H‐pyrrolo[1,2‐c]imidazole‐1,5(6H)‐dione. The chemical yields for the reference standards IUR‐1601 and IUR‐1602 were 12% and 13%, respectively. The chemical yields for the precursors Cl‐IUR‐1601 and Cl‐IUR‐1602 were 10% and 11%, respectively. One‐step radiosynthesis of [18F]IUR‐
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1601 and [18F]IUR‐1602 failed due to the elimination reaction under heating and basic conditions. The decay‐ corrected radiochemical yields for two‐step radiosynthesis of [18F]IUR‐1601 and [18F]IUR‐1602 from bis‐tosylate and K[18F]F/Kryptofix 2.2.2 with desmethyl‐GSK1482160 were 2‐7%, and the molar activity at the end of bombardment (EOB) was 74‐370 GBq/μmol. The binding affinity Ki values for IUR‐1601, IUR‐1602, spiral compound, and GSK1482160 were 3.73 ± 0.30 nM, 23.6 ± 0.96 nM, >10 μM, and 3.07 ± 0.24 nM, respectively. Conclusions The chemistry of [18F]IUR‐1601 and [18F]IUR‐1602 is highly similar. The [18F]fluoroalkylation of amide is a tough reaction, requiring high reaction temperature and strongly basic conditions. These are predisposing conditions for an elimination reaction, which caused one‐step radiosynthesis to fail and two‐step radiosynthesis with low radiochemical yield. Two new P2X7R radioligands [18F]IUR‐1601 and [18F]IUR‐1602 have been successfully radiosynthesized. The initial in vitro biological evaluation results suggest [18F]IUR‐1601 retained the P2X7R affinity of [11C]GSK1482160; [18F]IUR‐1602 remained low nM P2X7R affnity, but 8‐fold decrease compared to [18F] IUR‐1601 and [11C]GSK1482160. ACKNOWLEDGEMENTS This work was partially supported by Indiana University Showalter Young Investigator Award and Indiana University Department of Radiology and Imaging Sciences in the United States. R EF E RE N C E S 1. M. Gao, et al. Bioorg. Med. Chem. Lett. 2015, 25, 1965‐1970. 2. P.R. Territo, et al. J. Nucl. Med. 2017, 58, 458‐465.
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3. M.A. Green, et al. J. Nucl. Med. 2018, 59(S1), 1009. 4. M. Gao, et al. Bioorg. Med. Chem. Lett. 2018, 28, 1603‐1609. 5. D. van der Born, et al. Chem. Soc. Rev. 2017, 46, 4709‐4773. 6. M.‐R. Zhang, et al. J. Fluo. Chem. 2004, 125, 1879‐1886.
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-002 | Radiosynthesis of a novel 18F‐labeled triazole PET tracer for imaging GluN2B in the brain Hualong Fu1; Xiaofei Zhang2; Zhen Chen1; Qingzhen Yu1; Yihan Shao3; Shaofa Sun4; Hsiao‐Ying Wey1; Lee Josephson1; Zijing Li5; Stephen Traynelis6; Steven Liang1 1
MGH/Harvard, United States; 2 MGH/Harvard, China; 3 University of
Oklahoma, United States; 4 College of Nuclear Technology and Chemistry and Biology, Hubei University of Science and Technology, China; 5 Center for Molecular Imaging and Translational Medicine, Xiamen University, China; 6 Department of Pharmacology, Emory University School of Medicine, United States
Objectives GluN2B is one of the N‐Methyl‐D‐aspartate receptor (NMDAR) subunits and plays a significant role in determining the functional and pharmacological properties of NMDAR. The PET imaging of GluN2B subunit could help to understand the pathology of related diseases and accelerate the drug development.1 However, no clinically‐validated PET ligand is available to achieve accurate quantification of GluN2B subunit in the brain to date. Herein we developed a triazole‐based antagonist 2‐((1‐(4‐fluoro‐3‐methylphenyl)‐1H‐1,2,3‐triazole‐4‐yl)
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methoxy)‐5‐methoxypyrimidine (4, Figure 1) that are suitable for 18F‐labeling. The pharmacology evaluations were carried out to determine the potency and selectivity of 4 to GluN2B subunit, and [18F]4 was efficiently prepared by using our spirocyclic iodonium ylide (SCIDY) method2 through two steps. Methods As shown in Figure 1, the synthesis of cold compound 4 was initiated with the preparation of aromatic azide 2 in acidic conditions with 72% yield. The key intermediate 3 was obtained by “click” reaction between 2 and propargyl alcohol in 62% yield. Finally, compound 4 was afforded as a white solid (yield 17%) by SNAr reaction between 3 and 2‐bromo‐5‐methoxypyrimidine. The pharmacology evaluations were performed via glutamate/glycine (100μM/ 100μM) assays with Xenopus oocytes expressing GluN1 subunit with a GluN2 subunit including GluN2A– GluN2D. The precursor 6 was prepared as a yellowish solid from the oxidation of iodinated azidobenzene 5 with mCPBA, followed by ligand exchange with SPIAd3 in 36% yield. The treatment of 6 with [18F]F‐ in 0.4 mL anhydrous DMF containing 3.5 mg TEAB was afforded [18F]2, and the subsequent step was achieved by “click”
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reaction between [18F]2 and 7 (2‐3 mg) under the catalysis of CuI (2‐3 mg), which gave [18F]4 in high overall radiochemistry yield (RCY). The purification was carried out by high‐performance liquid chromatography (HPLC) using a YMC C18 reverse phase column (5 μm, 10 × 250 mm, elution: CH3CN/H2O = 40%/60%, 5 mL/min, tR = 19.8 min). Results Compound 4 was obtained as a white solid in three steps with the overall yield of 13% and showed high potency (IC50 = 28 nM) to GluN2B subunit and high selectivity toward GluN2A–GluN2D, GluA1, and GluK2 subunits. The precursor 6 was prepared in two steps with an excellent overall yield of 36%. The desired PET tracer [18F]4 was generated in two steps based on our SCIDY method in a high overall RCY of 39% (n = 5, decay corrected) after HPLC purification, and the total synthesis time was ~90 min. In addition, [18F]4 was provided in high radiochemistry purity >99% and a good molar activity of ~19 GBq/μmol (n = 5). The logD value of [18F]4 was measured by a shake‐flask method and determined to be 2.89 ± 0.037 (n = 3), which suggested a high probability for blood‐brain barrier (BBB) penetration.
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Conclusion The GluN2B‐selective antagonist 4 was successfully synthesized. Compound 4 display high potency and selectivity to GluN2B subunit, which identified it as a potent candidate for PET ligand development. Furthermore, [18F]4 was readily prepared by a SCIDY method in two steps with a high RCY and a good molar activity. This tracer has a proper logD value for BBB penetration and may be used as a feasible PET ligand for GluN2B imaging. PET imaging studies of [18F]4 will be reported in due course. R EF E RE N C E S 1. Mony L. et al. Br. J. Pharmacol. 2009;157:1301‐1317 2. Rotstein BH. et al. Nat. Commun. 2014;5:4365 3. Rotstein BH. et al. Chem. Sci. 2016;7:4407‐4417.
Poster Cate gory: Radiochemistry ‐ 18 F P-003 | Synthesis and evaluation of trialkyammonium salts as 18F labeling precursors for AZD4694 (NAV4694) Hui Xiong; Kuo‐Hsien Fan; Adam Hoye; Carey Horchler; Nathaniel Anthony Lim; Giorgio Attardo Avid Radiopharmaceuticals, Inc., a wholly‐owned subsidiary of Eli Lilly and Company, United States
We recently reported a convenient synthesis 2‐ trialkylammonium pyridines from readily accessible pyridine N‐oxides, and demonstrated the utility of this method
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in the successful preparation of [18F]AV‐1451. In this report, we would like to disclose an application of this methodology: a process of preparing the trialkylammonium salt precursor enabling highly efficient radiosynthesis of [18F]AZD4694, a beta‐amyloid PET tracer (also known as NAV4694). Methods/Results The trimethylammonnium precursor was prepared in 4 linear synthetic steps. The last step of conversion of pyridine N‐oxide to the corresponding trimethylammonnium salt was successful, albeit in low isolated yield (17%). Radiosynthesis of [18F]AZD4694 was achieved in 32‐41% isolated radiochemical yield (decay‐corrected). The synthesis time was around 1 hr. Conclusions Our reported method of late‐stage installation of trialkylammonium leaving group at 2 position of pyridine ring from the corresponding pyridine N‐oxides enabled the successful preparation of trimethylammonnium precursor for [18F]AZD4694, which might have been difficult to access otherwise. In comparison to the literature nitro precursor, significant improvement in the radiosynthesis efficiency was observed when using the new trimethylammonnium precursor, both in terms of higher isolated yield and shortened synthesis time.
RE FER EN CES 1. Xiong, H.; Hoye, A. T.; Fan, K.‐H.; Li, X.; Clemens, J.; Horchler, C. L.; Lim, N. C.; Attardo, G. Org. Lett. 2015, 17, 3726 – 3729 2. Swahn, B.‐M.; Sandell, J.; Pyring, D.; Bergh, M.; Jeppsson, F.; Juréus, A.; Neelissen, J.; Johnström, P.; Schou, M.; Svensson, S. Bioorg. Med. Chem. Lett. 2012, 22, 4332‐4337.
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3. Björk, S.; Delisser, V.; Johnström, P.; Nilsson, N. A.; Ruda, K.; Schou, P. M.; Swahn, B.‐M. WO2010024769A1, 2010.
Poster Cate gory: Radiochemistry ‐ 18 F P-004 | Simplified synthesis of [18F]NS12137 via copper‐mediated
18
F‐fluorination
Cu (OTf)2(py)4 with good elution efficiency. The subsequent reaction is not notably affected by the use of SPE system. ACKNOWLEDGMENTS This work was supported by the Academy of Finland (grant no. 266891 and 307924). RE FER EN CES 1. Kirjavainen AK et al. 2018, NMB, 56:39‐46
Salla Lahdenpohja; Noora Rajala; Anna Kirjavainen Turku PET Centre, University of Turku, Finland
Objectives [18F]NS12137 (exo‐3‐[(6‐[18F]fluoro‐2‐pyridyl)oxy]8‐ azabicyclo[3.2.1]octane) is a highly selective norepinephrine transporter (NET) tracer.1 Herein we introduce a simplified Cu‐mediated 18F‐fluorination of [18F]NS12137 (Fig 1), where azeotropic distillation of [18F]fluoride has been replaced by solid phase extraction (SPE). Methods Radiolabeling was performed with a semi‐automated synthesis device. Cyclotron produced [18F]fluoride was trapped into a custom made QMA carb SPE cartridge. The cartridge was washed with dimethylacetamide (DMA). [18F]fluoride was eluted with varied amount of Cu (OTf)2(py)4 and LiOTf in DMA. The reaction was heated at 120°C, and samples for analytical radio‐HPLC were collected at 1, 5, and 15 minutes. The protecting group was removed via acid hydrolysis at room temperature. Figure 1. Synthesis of [18F]NS12137 Results: [18F]Fluoride was successfully eluted from SPE cartridge with a 1:1 mixture of Cu (OTf)2(py)4 and LiOTf or by using 5 equivalents excess of Cu (OTf)2(py)4. Elution efficiency was up to 50%. The radiofluorination reaction proceeded with over 90 % radiochemical yield (RCY, non‐decay corrected, based on the HPLC analysis of the crude product), and the subsequent deprotection was nearly quantitative. When using more than 5 equivalents of Cu (OTf)2(py)4, the RCY of the radiofluorination reaction decreased. Excess of triflate ions from LiOTf did not affect the 18F‐labeling reaction. Conclusions [18F]NS12137 can be produced without the use of azeotropic distillation. [18F]Fluoride can be eluted from the SPE cartridge without any additional water by using
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-005 | Development, biological evaluation and PET application of [18F]fluoro‐glyco”RGD” Timothâ Vucko; Charlotte Collet; Gilles Karcher; Nadia Pellegrini Moïse; Sandrine Lamande‐Langle University de Lorraine, France
Objectives Glycosylation of peptides is known to enhance their bioavailability, pharmacokinetic, and in vivo clearance properties.1 In this context and in connection with our researches on the development of glycosylated prosthetic groups for PET (Positon Emission Tomography) imaging,2 we have developed new types of fluoro‐glyco”RGD” built with a stable C‐glycosidic bond.3 Methods As a powerful tool in the chemical ligation, the copper catalyzed azide alkyne cyclo addition (CuAAC) was selected to conjugate glycoside derivatives and RGD peptides containing a cysteine residue. Biological evaluation of the new conjugates was investigated on aIIbb3 and aVb3 integrins. Fully automated radiosynthesis of [18F]fluoro‐ glyco”RGD” was performed on an AllInOne synthesizer. Results Synthesis of carbohydrate‐based prosthetic groups and fluoro‐glyco”RGD” was efficiently performed. Biological evaluation on aIIbb3 and aVb3 integrins highlighted promising affinities and selectivity for two glycoconjugates. Radiosynthesis of [18F]fluoro‐glyco”RGD” was successful allowing the use of these derivatives as tools for diagnosis purposes in PET imaging.
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Conclusions New fluoro‐glyco”RGD” were developed and showed promising biological properties in terms of integrins selectivity. Full automation of [18F]fluoro‐glyco”RGD” synthesis was performed and could be applied to other prosthetic groups or peptides. [18F]fluoro‐glyco”RGD” could become valuable radiotracers for imaging of tumor angiogenesis in PET. R EF E RE N C E S 1. a) R. Haubner, B. Kuhnast, C. Mang, W. A. Weber, H. Kessler, H. J. Wester, M. Schwaiger, Bioconjugate Chem. 2004, 15, 61‐69. b) S. Maschauer, R. Haubner, T. Kuwert, O. Prante, Mol. Pharm. 2014, 11, 505‐515. 2. a) C. Collet, F. Maskali, A. Clément, F. Chrétien, S. Poussier, G. Karcher, P. ‐Y. Marie, Y. Chapleur, S. Lamandé‐Langle, J. Label. Compd. Radiopharm. 2016, 59, 54‐62. b) Y. Chapleur, S. Lamandé, C. Collet, F. Chrétien, WO 2014006022 A1 20140109, 2014. c) S. Lamandé‐Langle, C. Collet, R. Hensienne, C. Vala, F. Chrétien, Y. Chapleur, A. Mohamadi, P. Lacolley, V. Regnault, Bioorg. Med. Chem. 2014, 22, 6672‐6683. 3. N. Petry, T. Vucko, C. Collet, S. Lamandé‐Langle, N. Pellegrini‐ Moïse, F. Chrétien. Carbohydrate Res. 2017, 445, 61‐64.
Poster Cate gory: Radiochemistry ‐ 18 F P-006 | Radiosynthesis of [18F]FEDAC with the hydrous 18F‐fluorination using Kryptofix 222 and potassium carbonate. Kazunori Kawamura1; Katsushi Kumata2; Wakana Mori3; Masayuki Fujinaga4; Yusuke Kurihara5; Masanao Ogawa5; Nobuki Nengaki5; Ming‐Rong Zhang2 1
National Institute of Radiological Sciences, National Institute for
Quantum and Radiological Science and Technology, Japan; 2 Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3 Department of Radiopharmaceuticals Development,
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National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 4 National Institute of Radiological Sciences, Japan; 5 SHI Accelerator Service, Japan
Objectives Most 18F‐labeled radiopharmaceuticals are prepared via aliphatic and aromatic nucleophilic substitution reaction with 18F‐. Owing to hydration, water significantly diminishes the nucleophilicity of 18F‐. To remove the bulk of water, 18F‐ is trapped on the Sep‐Pak QMA cartridge, and water is removed by time‐consuming repetitive azeotropic drying from an aqueous solution of potassium carbonate (K2CO3) and Kryptofix 222 (K222) as an elution from the Sep‐Pak QMA cartridge. To develop an easy and fast fluorination without the use of azeotropic drying, Kniess T. et al. established the concept of hydrous 18F‐fluorination using K2CO3 and K222 [ref. 1]. Recently, to transfer the production technique of [18F]FEDAC to other PET centers, we developed an efficiently radiosynthetic method of [18F]FEDAC in the one‐pot [ref. 2]. To achieve an easy and fast radiosynthesis, we examined the radiosynthesis of [18F]FEDAC with the hydrous 18F‐fluorination using K2CO3 and K222 in the one‐pot. Methods [18F]FEDAC was synthesized with the hydrous 18F‐fluorination in two routes from tosyl‐precursor or desmethyl‐ precursor. [18F]F‐ was trapped on the Sep‐Pak QMA cartridge, and eluted with the solution (1 mL, 0.2% water in acetonitrile) of K222 (12‐15 μmol) and K2CO3 (6‐ 8 μmol). In the case of direct 18F‐fluorination of tosyl‐ precursor, the eluent from the Sep‐Pak QMA cartridge was loaded into the vessel in which tosyl‐precursor (1‐ 4 mg, 3‐7 μmol) was added in advance, and the mixture solution was heated at 100°C for 15 min. After the solution was evaporated to dryness, the eluent of HPLC was added into the vessel, and the reaction mixture was loaded into the injector of preparative HPLC. In the case of 18F‐fluoroethylation of desmethyl‐precursor in the one‐pot, the eluent from the Sep‐Pak QMA cartridge
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was loaded into the vessel in which ethylene glycol ditosylate (2.4‐3.1 mg, 7‐8 μmol) and cesium carbonate (2.1‐2.8 mg, 7‐8 μmol) were added in advance, and the mixture solution was heated at 100°C for 5 min. After the solution was evaporated to dryness, the desmethyl‐ precursor (2.6‐3.0 mg, 7‐8 μmol) in DMSO (0.5 mL) was added into the vessel and the mixture solution was heated at 100°C for 15 min. After the eluent of HPLC was added into the vessel, the reaction mixture was loaded into the injector of preparative HPLC. HPLC fractions of [18F] FEDAC were collected and evaporated to dryness, and the residue was dissolved in physiological saline. Results In the radiosynthesis with the hydrous 18F‐fluorination of tosylated‐precursor, the radiochemical yield (RCY) from [18F]F‐ was 15% (1 mg of precursor) at the end of irradiation (EOI). In the previous study with azeotropic drying, the RCY from [18F]F‐ was 19% (1 mg of precursor) at EOI [ref. 2]. Although the RCY in this study was close to that in the previous study, the present synthesis time (approx. 53 min) was shorter than that in previous study (70 min) [ref. 2]. Furthermore, we optimized this radiosynthesis with the hydrous 18F‐fluorination of tosylated‐precursor, and the RCY from [18F]F‐ was achieved over 20% at EOI by the use of 4 mg (7 μmol) of precursor. In the case of 18 F‐fluoroethylation of desmethyl‐precursor in the one‐ pot, the RCY from [18F]F‐ was approximately 10% at EOI. In the previous study with azeotropic drying in the two‐ pots, the RCY from [18F]F‐ was 24% (1 mg of precursor) at EOI [ref. 2]. Although the RCY in this study was lower than that in the two‐step reaction, the present synthesis time (60 min) was shorter than that in previous study (90 min). Conclusion We enabled to synthesize [18F]FEDAC easily and rapidly with the hydrous 18F‐fluorinaiton in the one‐pot. R EF E RE N C E S 1. T. Kniess, M. Laube, and J. Steinbach, Appl Radiat Isot. 2017, 127, 260–8. 2. K. Kawamura, K. Kumata, T. Takei. et al, Nucl Med Biol. 2016, 43, 445–53.
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P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-007 | Synthesis and application of [18F] fluorobenziodoxole Miguel Cortes Gonzalez1; Patrik Nordeman2; Antonio Bermejo Gomez1; Denise Meyer1; Gunnar Antoni2; Magnus Schou3; Kalman Szabo1 1
Stockholm University, Sweden; 2 Uppsala University Hospital, Sweden;
3
AstraZeneca PET Centre at Karolinska Institutet, Sweden
Objectives The objective of this work is the application of [18F] fluorobenziodoxole,1 an electrophilic 18F‐fluorinating reagent that was prepared from a nucleophilic 18F‐fluorine source. Methods [18F]Fluorobenziodoxole,1 was prepared by nucleophilic substitution of TsO‐benziodoxole precursor using nucleophilic [18F]Bu4NF and was purified by extraction. [18F] Fluorobenziodoxole was used1 for fluorocyclization reactions2 to obtain [18F]fluorobenzoxazepines. In subsequent studies, we used [18F]fluorobenziodoxole reagent for a 18 metal‐catalyzed F‐fluorination‐based difunctionalization of diazoketones. Results [18F]Fluorobenziodoxole was successfully employed in the synthesis of [18F]fluorobenzoxazepines, obtaining good to very good radiochemical yields (50‐90% estimated by HPLC analysis of the crude reaction mixture) and a molar activity of 396 GBq/mmol. Conclusions We have developed a method for synthesis of [18F] fluorobenziodoxole, an electrophilic 18F‐fluorination reagent. [18F]Fluorobenziodoxole was applied in the synthesis of [18F]fluorobenzoxazepines in high radiochemical yield and molar activity. ACKNOWLEDGMENTS Support by the Stockholm Brain Institute, Vinnova, and the Swedish Research Council is gratefully acknowledged.
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R EF E RE N C E S 1. M. A. Cortes Gonzalez, P. Nordeman, A. Bermejo Gomez, D. N. Meyer, G. Antoni, M. Schou, K. J. Szabo, Chem. Commun. 2018, 54, 4286‐4289. 2. A. Ulmer, C. Brunner, A. M. Arnold, A. Pothig, T. Gulder, Chem. Eur. J. 2016, 22, 3660‐3664.
Poster Cate gory: Radiochemistry ‐ 18 F P-008 | Synthesis of 6‐[F‐18]Fluoropyridine‐3‐ carbaldehyde‐O‐[4‐(2,5‐dioxo‐2,5‐dihydropyrrol‐ 1‐yl)butyl and pentyl]oximes, novel thiol reactive bifunctional agents for peptide labeling Murthy Akula1; David Blevins2; George Kabalka3; Dustin Osborne4 1
University of Tennessee Medcial center, United States; 2 The University of
Tennessee, GSM, United States; 3 University of Tennessee Medical Center, United States; 4 The university of Tennessee Medical Center, United States
Objective Direct radiofluorination of sensitive biomolecules such as proteins and nucleotides is rarely carried out because of the harsh reaction conditions. These sensitive molecules have been successfully radiofluorinated using bifunctional agents otherwise called prosthetic groups. Some of the prominent thiol reactive prosthetic groups include [F‐18]FBAM1, [F‐18]FPyMe2, and [F‐18]FPyrAM3. We wish to report two novel pyridine based bifunctional agents 7 and 8.
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Methods The requisite precursors 3 and 4, to condense with 6‐[F‐ 18]fluoropyridine‐3‐carboxaldehyde, 6, were prepared from 1,4‐butanediol and 1,5‐pentanediol in five steps in over all yields of 16% and 18%, respectively. The radiofluorination of previously4 known DABCO pyridinyl salt 5 was carried out on Sofie Elyxis Radiochemistry Platform to obtain the aldehyde 6 that was condensed with the maleiimde linker 3 or 4 to obtain the title compounds 7 or 8. Results Cyclotron produced [18F]fluoride (~100 mCi) was trapped on a QMA cartridge and eluted into a reaction vessel with kryptofix‐potassium carbonate solution and thoroughly dried using a drying sequence optimized on Sofie box. The radiofluorination was carried out with DABCO chloride 5 (16.0 mg in 1.0 mL DMSO) at 50°C for 15 min. To the crude solution of 6‐[18F]fluoronicotinaldehyde (6) was transferred maleimide precursor 3 or 4 (16 mg in 1.0 mL 50% methanol in 6N HCl). The mixture was heated at 75°C for 15 min. The reaction mixture was then diluted with water (10 mL) and passed through a C18 Sep‐Pak cartridge. The cartridge was washed with water (5 mL), and the crude product was eluted with CH3CN (3 mL). Eluted product was further diluted with water (2 mL) before loading into the injection loop. Semipreparative HPLC purification was performed using a Luna C18 column, 5μ, 10 × 250 mm; 4 mL/min.(A: CH3CN, B: 0.1 M ammonium formate); 0‐5 min 40%A and 60%B; 5‐15 min 40%A‐70%A; 15‐30 min 70% A). A fraction (25‐27 min) was collected diluted with water (10 mL) and passed through a C18 Sep‐Pak cartridge. The cartridge was washed with diethyl ether (2 mL), and the solvent evaporated in a stream of N2 to afford 40‐45 mCi (40‐45%) of 7 or 8. The radiochemical purity (Agilent 1200 Binary) was determined to be
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≥98%. The identity of the product was confirmed by the co‐elution with the cold compound. Conclusions Two new thiol reactive bifunctional agents were successfully synthesized (n = 4) with high radiochemical yields (40‐45%) and purity >98%. The advantage of DABCO salt is that it does not produce volatile Me[F‐18]F generally observed when trimethylammonium triflates are used. ACKNOWLEDGEMENTS The funding for this research was supported by Molecular Imaging Translational Research Programme, the Radiology Department. R EF E RE N C E S 1. M. Brendt, et al. (2007) Nucl Med Biol, 34, 5. 2. B. Bruin, et al. (2005) Biocon. Chem, 16, 406. 3. M. Akula et al. (2013) J Label Compd Radiopharma, 56, S44. 4. M. Akula et al. (2015) J Label Compd Radiopharma, 58, S198.
Poster Cate gory: Radiochemistry ‐ 18 F P-009 | Synthesis and biological investigation of a novel fluorine‐18 labeled benzoimidazotriazine: A Potential radioligand for in vivo phosphodiesterase 2A (PDE2A) PET imaging Rien Ritawidya; Rodrigo Teodoro1; Barbara Wenzel2; Mathias Kranz; Magali Toussaint2; Sladjana Dukic‐Stefanovic; Winnie Deuther‐Conrad; Matthias Scheunemann2; Peter Brust2 1
Institute of Radiopharmaceutical Cancer Research, Helmholtz‐Zentrum
Dresden Rossendorf, Germany; 2 Helmholtz‐Zentrum Dresden‐Rossendorf, Germany
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Objectives Cyclic nucleotide phosphodiesterase 2A (PDE2A), an enzyme which hydrolyzes the second messengers cAMP and cGMP, is highly enriched in distinct areas of the brain. Accordingly, PDE2A is involved in important signaling pathways related to normal brain function but also to neurodegeneration and neuro‐oncology.1 To enable the visualization of this protein in the brain with PET, we developed a novel fluorine‐18 radioligand for PDE2A. Methods Based on the benzoimidazotriazine (BIT) tricyclic scaffold, several fluorine‐containing derivatives were synthesized via a multi‐step synthesis route, and their inhibitory profiles were assessed by PDE isoenzyme‐ specific activity assays. The most potent and selective PDE2A ligand BIT1 was radiolabeled via nucleophilic aromatic substitution of the corresponding 2‐nitro pyridine precursor by [18F]fluoride in DMSO with thermal heating (Figure 1). [18F]BIT1 was isolated using semi‐ preparative HPLC (Reprosil‐Pur C18‐AQ column, 250 × 10 mm, 46% ACN/aq. 20 mM NH4OAc, flow 5.5 mL/min) followed by final purification with solid‐ phase extraction and formulation in isotonic saline containing 10% ethanol. Preliminary in vitro autoradiography and in vivo PET studies (60 min dynamic PET imaging, nanoScan PET/MRI, MEDISO, Budapest, Hungary) of [18F]BIT1 were performed using pig brain slices and female CD‐1 mice, respectively. The in vivo metabolism of [18F]BIT1 was investigated by radio‐HPLC analysis of mouse plasma and brain samples at 30 min p.i. Results From the series of BIT derivatives, BIT1 was selected as candidate for PET imaging of PDE2A based on the most suitable inhibitory potential and profile (IC50 PDE2A3 = 3.3 nM; 16‐fold selectivity over PDE10A). [18F]BIT1 was successfully synthesized with a radiochemical yield of 54 ± 2% (n = 3, EOB), molar activities of 155–175
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GBq/μmol (EOS) and radiochemical purities of ≥99%. [18F]BIT1 was stable in saline, pig plasma, and n‐octanol up to 60 min at 37°C. The distribution pattern of [18F] BIT1 in pig brain cryosections corresponds to the spatial distribution of PDE2A with accumulation in the striatal regions caudate nucleus and nucleus accumbens. Additionally, the displacement of [18F]BIT1 with BIT1 as well as TA1 (a potent PDE2A ligand) indicated saturability and selectivity of these binding sites. Uptake of [18F]BIT1 in the brain was shown by subsequent imaging studies in mice (SUVwhole brain = 0.7 at 5 min p.i.); however, more detailed analyses revealed nonspecific distribution of the tracer in the brain (78% parent compound at 30 min p.i.). Conclusions The potent and selective PDE2A inhibitor [18F]BIT1 binds in vitro in brain regions known to express PDE2A. Further structural modifications will be performed to develop radiotracers with improved brain uptake and target‐selective accumulation in vivo. ACKNOWLEDGEMENT 1. Deutsche Forschungsgemeinschaft (German Research Foundation, SCHE 1825/3‐1). 2. Scholarship Program for Research and Innovation in Science and Technology Project (RISET‐PRO)‐Indonesia Ministry of Research, Technology and Higher Education (World Bank Loan No: 8245‐ID) R EF E RE N C E S 1. S. Schröder, B. Wenzel, W. Deuther‐Conrad, M. Scheunemann, P. Brust, Novel Radioligands for Cyclic Nucleotide Phosphodiesterase Imaging with Positron Emission Tomography: An Update on Developments Since 2012, Molecules 21 (2016) 650–685.
Poster Cate gory: Radiochemistry ‐ 18 F P-010 | A simple SPE purification method for 18
F‐radiolabeling: Proof‐of‐concept study in stilbene amyloid‐β ligands with a neopentyl labeling group
Tetsuro Tago1; Jun Toyohara1; Ryo Fujimaki2; Keiichi Hirano3; Kumiko Iwai3; Kenji Ishibashi1; Hiroshi Tanaka2 1
Tokyo Metropolitan Institute of Gerontology, Japan; 2 Tokyo Institute of
Technology, Japan; 3 NMP Business Support Co., Ltd., Japan
Objectives To develop a simple radioligand purification method by solid‐phase extraction (SPE), we applied an 18F‐labeling group containing a 2,2‐dihydroxymethyl‐1‐[18F]fluoropropane (JP2017052713) (Figure 1A). An advantage of
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the 18F‐labeling group is to provide [18F] fluorinated products without alkenyl by‐products by β‐elimination. We also adopted a highly lipophilic leaving group to remove the intact precursor and the desorbed leaving group from the reaction mixtures by SPE. Herein, we select stilbene compounds as model compounds to demonstrate the utility of the neopentyl 18F‐labeling group for PET imaging of amyloid‐β in Alzheimer's disease.1 Methods Preliminary radiosynthesis experiments of a neopentyl compound ([18F]1) were performed using a COSMiC‐Mini synthesizer (NMP Business Support Co., Ltd., Fig. 1B). Briefly, 18F‐anion (about 100 MBq) trapped on a Sep‐ Pak® QMA cartridge (Waters) was eluted with a mixture of K2CO3 (2.0 mg/0.3 mL H2O) and Kryptofix® 222 (11 mg/0.7 mL CH3CN) to the first reaction vial followed by azeotropic drying with CH3CN (0.5 mL × 3). 4‐(Didodecylcarbamoyl)benzenesulfonate precursor (5 mg/500 μL CH3CN) was added and then the mixture was heated at 110°C for 30 min. After dilution with 30% aqueous CH3CN solution, the reaction mixture was passed through the first Sep‐Pak® C8 cartridge. The cartridge was washed with 30% aqueous CH3CN solution followed by H2O. An 18F‐labeled intermediate was eluted with 80% aqueous CH3CN solution (2 mL) into the second reaction vial. 5 M HCl (1.8 mL) was added, and then the mixture was heated at 110°C for 3 min. The reaction mixture was neutralized with 1 M NaHCO3 and passed through the second C8 cartridge. After washing with H2O, the final product was eluted with EtOH (2 mL). Identification and radiochemical purity analysis of the product was performed by radio‐thin‐layer chromatography. The radioligands that were used for the following biological experiments were obtained using an F100 synthesizer (Sumitomo Heavy Industries, Ltd.) with a conventional semi‐preparative HPLC equipment. Four ligands with different lengths of polyethylene glycol linkers (PEG = 0, 1, 2, or 4) that bridge the neopentyl group and the stilbene framework were synthesized. Saturation binding assays were performed for synthetic Aβ1‐42 aggregates. Pharmacokinetics in normal mice (ddY, male, 8 week‐old) were assessed by ex vivo biodistribution studies. Results Using an SPE purification method, [18F]1 was obtained with radiochemical yield and radiochemical purity of 22.2 ± 10.0% (decay‐corrected) and 94.1 ± 2.5%, respectively (n = 3). HPLC analysis (λ = 254 nm) revealed that more than 95% of the precursors were removed from the crude reaction mixture by the first SPE step (Fig. 1C). Dissociation constants of the radioligands for Aβ1‐42 aggregates were low (Kd = 3.6–23 nM), suggesting that the neopentyl side‐chain did not disturb Aβ‐
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binding to stilbenes. All radioligands except [18F]4 showed sufficient brain uptake at 2 min post‐injection (3.0–4.2% ID/g) followed by gradual reduction. Moderate radioactivity accumulation in the bone (4.2% ID/g at 120 min post‐injection) was observed for only [18F]4, indicating its relatively high sensitivity for in vivo defluorination. Conclusions In our preliminary experiments, an 18F‐labeled neopentyl stilbene compound was radiosynthesized employing an SPE purification method. Among the tested compounds, [18F]2 had the most promising properties as an Aβ radioligand, such as a high binding affinity for Aβ1‐42 aggregates and high brain uptake in mice. These results
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showed a proof‐of‐concept of the simple SPE purification method based upon the novel neopentyl 18F‐labeling group and that the labeling group is feasible for a stilbene Aβ radioligand. ACKNOWLEDGEMENTS This work was supported by the Grant‐in‐Aid for the Development of Advanced Measurement and Analysis Systems from Japan Sciences and Technology Agency. We thank Mr. Kunpei Hayashi and Mr. Masanari Sakai (SHI Accelerator Service Ltd.) for technical assistance. RE FER EN CES 1. W Zhang et al., Nucl Med Biol. 2005;32:799.
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Pos ter Category : Ra dio c h e m istr y ‐ 18 F P-011 | Design of a new 18F‐prosthetic reagent for the “thiol‐ene”‐Dha‐based conjugation with proteins Mylène Richard; Simon Specklin; Francoise Hinnen; Bertrand Kuhnast Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris‐Saclay, Service Hospitalier Frédéric Joliot, France
Objectives 18 F‐radiolabeled reagents containing a thiol moiety for the prosthetic labeling of biologics have not been widely used so far. A series of 18F‐fluorothiols was first developed for the conjugation with the chloroacetylated N‐terminus of peptides 1 and more recently, a thionated version of 18F‐ FDG was described for the site‐specific “thiol‐ene” conjugation with peptides and proteins displaying a dehydroalanine residue introduced by post‐translational modification of a cysteine.2 Based on this conjugation strategy, we report herein the design, synthesis, and radiosynthesis of a new fluoropyridine‐based thiol‐ containing reagent. Its conjugation via a “thiol‐ene” reaction was exemplified on a dehydroalanine model compound. Methods Reference prosthetic reagent 3 was prepared in two steps starting from 2‐fluoro‐3‐hydroxypyridine (1) and diethylene glycol compound 2. Non‐radioactive conjugate 5 was then obtained by reaction of the prosthetic reagent 3 with the dehydroalanine model compound 4. Tritylated radiolabeling precursor 6 was prepared in two steps by alkylation of the 2‐dimethylamino‐3‐hydroxypyridine with compound 2 followed by methylation of the
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dimethylamino moiety. Standard radiofluorination conditions involving precursor 6 (5 mg) and K[18F]F‐K222 provided the prosthetic reagent [18F]‐3. After a pre‐ purification using a C18 cartridge, the trityl protective group was removed before RP‐HPLC purification. The preparation of [18F]‐3 was fully automated on a TRACERLab Fx N Pro synthesizer (GEMS). An aliquot of [18F]‐3 was then reacted with 4 in reductive conditions to avoid disulfide dimerization, affording the radioactive conjugate [18F]‐5. The conversion was monitored by analytical RP‐HPLC and radioTLC. Results Reference prosthetic reagent 3 and the radioactive precursor 6 were prepared in 88% and 83% yield over two steps, respectively, and the non‐radioactive conjugate 5 was obtained in 83% yield. The radiolabeling precursor 6 was prepared in 72% yield over two steps. The 18F‐ labeled prosthetic reagent [18F]‐3 was radiolabeled in 20% decay‐corrected yield in 60 min synthesis time. Typically, starting from a 31 GBq [18F]F‐ production batch, 6.2 GBq of pure [18F]‐3 could be collected. After 1 hour incubation of 4 with [18F]‐3, the radiochemical identity of the radioactive conjugate [18F]‐5 was assessed by analytical HPLC and the conjugation yield was evaluated by radioTLC to 37%. Conclusion The prosthetic reagent [18F]‐3 could be prepared fully automatically in good yields. The conjugation via “thiol‐ ene” reaction was established and the optimization of the conjugation conditions is in progress. ACKNOWLEDGMENTS Supported by the CEA‐DRF‐Impulsion IRIP intramural program.
RE FER EN CES 1. Glaser M et al. Bioconjugate Chem (2004), 15, 1447. 2. Boutureira O et al. ChemComm (2011), 47, 10010.
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Poster Cate gory: Radiochemistry ‐ 18 F P-012 | Cobalt‐catalyzed C–F bond borylation of aryl fluorides for PET applications Eunsung Lee Pohang University of Science and Technology
Fluorine atoms can be found in a variety of organic molecules such as pharmaceuticals, agrochemicals, and polymeric materials. In line with an importance of fluorinated compounds, there have been significant advances on C―F bond formation for the past decades. However, unlike a development of C―F bond formation reactions, C―F bond functionalization has been limited to either highly activated C―F bonds or C―C bond formation. In 2015, C―F functionalization of unactivated fluoroarenes has been developed by the Marting group and the Niwa and Hosoya group demonstrating Ni‐ catalyzed defluoroborylation of fluoroarenes and its application to F‐18 radiochemistry and further organic transformations.1 Although the methods are efficient and top‐notched, there are still some limitations: high reaction temperatures, limited functionality‐tolerance, and operational difficulty. In order to overcome the barriers, we have been explored Co‐based catalysis, and here we present cobalt‐catalyzed unactivated aryl C―F bond borylation. This reaction can be set up in air and does not require a presynthesized organometallic complex. A mild and practical Co‐catalyzed borylation of various fluoroarenes enables a new reaction strategy in synthetic chemistry.2 Furthermore, this method was successfully applied to synthesize complex [18F]fluoroarenes with great radiochemical yields. The details will be discussed. R EF E RE N C E S 1. (a) Liu, X.; Echavarren, J.; Zarate, C.; Martin, R. J. Am. Chem. Soc. 2015, 137, 12470–12473. (b) Niwa, T.; Ochiai, H.; Watanabe, Y.; Hosoya, T. J. Am. Chem. Soc. 2015, 137, 14313−14318. 2. Lim, S.; Song, D.; Jeon, S.; Kim, Y.; Kim, H.; Lee, S.; Cho, H.; Lee, B. C.; Kim, S. E.; Kim, K.; Lee, E. R. Org. Lett. 2018, 20, 7249–7252.
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P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-013 |
18
F‐fluorination of BaGdF5 nanoparticles for multimodal imaging and PET/CT biodistribution in mouse. Laura Fernandez‐Maza1; Ariadna Corral2; Ana Becerro3; Daniel Gonzalez4; Angel Parrado2; Marcin Balcerzyk5; Manuel Ocana6 1
Universidad de Sevilla, CSIC, Junta de Andalucía, Spain; 2 Universidad de
Sevilla, CSIC, Junta de Andalucia, Spain; 3 CSIC, Universidad de Sevilla, Spain; 4 CSIC,Universidad de Sevilla, Spain; 5 Universidad de Seville, CSIC, Junta de Andalucia, Spain; 6 CSIC, Junta de Andalucia, Spain
Objective Rare earth nanoparticles are promising multimodal imaging agents. Due to their physico‐chemical properties, they are useful in different diagnostic techniques (1); bioluminescence, magnetic resonance (MRI), computed tomography (CT), and positron emission tomography (PET). At present work, Barium Gadolinium pentafluoride (BaGdF5) nanoparticles were labelled with fluorine‐18 for PET and CT images in a BALB/c female mouse. Methods 2960 MBq of [18F]fluoride were obtained in a 18/9 MeV Cyclone cyclotron (IBA Belgium) and sent directly to the reactor chamber of a TracerLab FXFN synthesis module (General Electric). As the BaGdF5 nanoparticles are unstable in presence of salts, [18F]fluoride could not be preconcentrated in quaternary methyl ammonium resin, nor eluted with potassium carbonate, as usual. To ensure the absence of long half‐life contaminants from the Havar alloy, the main product of bombardment was used for another purpose, and for our experiment we used a rinse of 500 μL of water, to carry the [18F]fluoride to the reactor. Gamma spectra were performed for three days to look for long‐lived contaminant isotopes. Once the [18F]fluoride was at the reactor, the nanoparticles suspension was added to the [18F]fluoride. The BaGdF5 nanoparticle concentration was adjusted to 0.5 mg/mL with water per injection, to limit the number of nanoparticles injected to the mouse. The labeling reaction took place at 37°C during ten minutes in continuous stirring. No further purification was performed.
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Before injection to the animal, quality control was performed by instant thin layer chromatography (ITLC) in a MiniGITA (Raytest) Radiochromatograph to ensure radiochemical purity, pH control, and visual inspection, and to verify the absence of nanoparticle aggregation. 13.2 MBq of radioactive nanoparticles were injected in the lateral tail vein of a healthy control mouse, and dynamic PET images were acquired for 20 minutes in a Mosaic MicroPET scanner (Philips). CT acquisition followed PET scan. The animal was anaesthetized during both studies, so that PET images were attenuated corrected with the anatomical images. Both studies were analyzed with PMOD 3.0 (Mediso). In vitro stability was tested in previous tests, incubating 0.5 mg/mL of BaGdF5 nanoparticles in human plasma and complete blood, to observe nanoparticle aggregation at CT (45 Kv,
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0.2 mm of spatial resolution, 500 ms exposition time, 240 projections) in a NanoSPECT/CT (Bioscan). Results No clogging of BaGdF5 nanoparticles was observed at CT. Gamma spectra did not show peaks corresponding to contaminating isotopes compared to background activity, in the expected energy range (0‐2000 KeV). 2738 MBq of [18F] BaGdF5 nanoparticles were obtained at end of synthesis, with a radiochemical purity of 90.65% (ITLC silicagel as stationary phase, NaCl 0.9% mobile phase). pH in physiological range. Conclusion As [18F]BaGdF5 nanoparticles are not yet functionalized, the main activity uptake was in liver and spleen. Later images showed increasing kidney and bladder uptake, that suggest renal clearance. No activity was seen in
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bowel. The animal was still alive two months later, in observation, with no symptoms of toxicity. Further studies will be performed with nanoparticles bioconjugation to different peptides to direct this multimodal imaging agent to different tumor targets. ACKNOWLEDGEMENTS Authors would like to thank Siemens Healthineers by support in part this work. R EF E RE N C E 1. González‐Mancebo D., Becerro A.I., Genevois C., Allix M., Corral A., Parrado A., Ocaña M. Structural, optical and X‐ray attenuation properties of Tb3+:BaxCe(1‐x)F(3‐x) (x=0.18‐0.48) nanospheres synthesized in polyol medium, Dalton Transactions 2018, 47, 8382‐8391.
Poster Cate gory: Radiochemistry ‐ 18 F P-014 | 4‐Nitrophenyl activated esters are superior synthons for indirect radiolabelling of biomolecules; A direct radiofluorination tolerance and acylation kinetics study Mohammad Haskali1; Ashleigh Farnsworth2; Rodney Hicks3; Peter Roselt1; Craig Hutton2 1
Peter MacCallum Cancer Centre, Australia; 2 School of Chemistry and
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Methods PNP and TFP esters of (4‐carboxyphenyl)(4‐methoxyphenyl)iodonium tosylates (compounds 1 and 2) and 5‐ carboxy‐2‐trimethylammoniopyridine (compounds 3 and 4) were prepared. Compounds 1–4 were treated with Kryptofix 2.2.2./potassium [18F]fluoride complex at 100°C in DMSO:amyl alcohol (4:6). The corresponding [18F]‐products were acylated with varying concentrations of benzylamine, as a model substrate. Results PNP esters of both 4‐[18F]fluorobenzoate [18F]5 and 6‐[18F]fluoronicotinate [18F]6 were prepared in 88% and 95% yield, respectively. The TFP ester of 4‐[18F] fluorobenzoate [18F]7 was prepared in 0‐31% yield and 6‐[18F]fluoronicotinate [18F]8 in 34‐75% yield under identical conditions to their PNP ester analogues. Acylation rates of PNP esters [18F]5 and [18F]6 were found to be higher and more reproducible than that of TFP ester [18F]8. Acylation rates of ester [18F]7 was not studied due to the poor formation yields. Conclusion PNP esters demonstrated superior tolerance under direct radiofluorination conditions and afforded higher acyaltion reactivity and reproducibility.
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F
Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Australia; 3 The Peter MacCallum Cancer Centre, Australia
Aim To evaluate the tolerance of 4‐nitrophenyl (PNP) and 2,3,4,5‐ tetrafluorophenyl (TFP) esters to direct radiofluorination conditions for the preperation of two useful synthons for the indirect radiolabelling of peptides; namely their 4‐[18F] fluorobenzoate and 6‐[18F]fluoronicotinate analogues. Furthermore, we aim to determine the relative acylation kinetics of these PNP and TFP esters.
P-015 | Automated radiosynthesis of a PDE10A PET radiotracer: [18F]TZ20A ‐ two‐pot, two‐step, and two‐HPLC purification on one module Jinda Fan1; Norio Yasui; Zonghua Luo2; Zhude Tu3 1
UAB, United States; 2 Washington University School of Medicine in Saint
Louis, United States; 3 Department of Rdiology, Washington University School of Medicine in Saint Louis, United States
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Objectives Phosphodiesterase 10A (PDE10A) is a dual‐substrate specific PDE that degrades both cAMP and cGMP, secondary messengers playing critical regulatory roles in live cells. Restricted expression in striatum of brain, PDE10A has been shown was implicated in the pathophysiology of neurodegenerative and neuropsychiatric disorders such as the Huntington disease, Parkinson disease, and schizophrenia. PDE10A inhibitors have been studied for the treatment of these diseases. Consequently, PDE10A specific, both C‐11 and F‐18 labeled radio ligands were developed for the quantification and visualization of this enzyme in vivo using PET. Recently, it was reported that PDE10A protein level is elevated in several different types of human tumors, such as colon, lung and breast tumors, and that highly specific PDE10A inhibitors selectively inhibit cancer cell growth, leading to the exploration of developing small molecule inhibitors for the chemoprevention and therapy of these
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mentioned types of cancers. To facilitate the anti‐cancer drug development on this novel target, PET imaging can serve as a useful tool. Therefore, there was a demand for PDE10A specific radiotracers. For our application, we selected [18F] TZ20A, a potent (IC50 = 0.26 nM) and selective (>1000 times over other PDEs) radiotracers for PDE10A, and developed a method for the automated radiosynthesis of the tracer. Methods The radiosynthesis of [18F]TZ20A was performed by a two‐ step labeling strategy using 2‐[18F]fluoroethyl tosylate (Scheme 1) as an intermediate, using a customized Synthra RNplus module (Figure 1). Nucleophilic F‐18 substitution of aliphatic tosylate was conducted to get the desired 2‐[18F] fluoroethyl tosylate. The intermediate was purified on a HPLC system using a semi‐preparative C‐18 column, acetonitrile/0.1M pH 4.5 formate buffer solution as mobile phase, then processed via a C‐18 Sep‐Pak cartridge, eluted with ether, and dried by going through Sep‐Pak Dry
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cartridge, subsequently removing ether, coupled with precursors containing phenol on the quinoline moieties, using cesium carbonate as a base, and DMSO as the solvent. The final product was purified on a HPLC system using semi‐ preparative C‐18 column, acetonitrile/0.1M pH 4.5 formate buffer solution as mobile phase, then processed via a C‐18 Sep‐Pak cartridge, eluted with ethanol, and formulated to 10% ethanol in sterile 0.9% NaCl solution. The whole process, two‐step synthesis and two‐HPLC purification were all completed on one module, including the purification and drying process of intermediated 2‐[18F]fluoroethyl tosylate, under optimized conditions, using 0.020 ID peek tubing to control the flow rate of ether through Sep‐Pak Dry cartridge. Results Starting with 500‐1000 mCi of F‐18 in O‐18 water from cyclotron target, through two‐step radiosynthesis and two HPLC purification, 50‐100 mCi of [18F]TZ20A were routinely produced in 120‐130 minutes. The F‐18 incorporation rate was 60‐70% and the coupling reaction yield was 40‐50% based on HPLC chromatograms. The overall radio‐chemical yield is 20‐25% (corrected to EOB). The final product has a high chemical purity (>95%, n > 12), high radiochemical purities (>99%, n > 12), and decent molar activity of >3.5 ± 1.0 Ci/μmol (>129.5 ± 37 GBq/μmol at time of EOS). Conclusions Two‐step radiosynthesis of [18F]TZ20A was accomplished on one synthesis module, including two HPLC purification process. Particularly, the purification, isolation, and drying of 2‐[18F]fluoroethyl tosylate was also conducted on the module automatically. The automation not only cut the synthesis time but dramatically simplified the operation and substantially reduced the radiation exposure and personal dose compared to the manual synthesis. The optimized method has also been applied in the radiosynthesis of other radiotracers containing the common [18F]fluoroethoxy moieties on aromatic rings. Research Support UAB RRIPA
Poster Cate gory: Radiochemistry ‐ 18 F
P-016 | Radiosynthesis of [18F] Fluoroaminoesters by deoxyradiofluorination of b‐hydroxy‐a‐aminoesters under mild conditions
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Objectives Aminoacid derivatives bearing a fluorine‐18 atom at vicinal aliphatic position have found widespread applications in PET imaging.1 The main radiochemical approaches involved the substitution reaction of halides2 or sulfonates,3 and the ring opening of sulfamidates4 or aziridines5 using [18F]fluoride. These reactions required heating conditions and the preparation of precursors may involve a multi‐step synthesis. Recently, late‐stage manganese salen and decatungstate‐catalyzed C‐H radiofluorinations were reported, but they were restricted to benzylic or branched [18F]fluoroaminoacids.6 Previously, we developed a new aliphatic radiofluorination approach via an aziridinium intermediate, allowing an efficient and rapid access to β‐[18F] fluoroamines from ethanolamines under room temperature conditions.7 We thought that extension of this methodology to β‐hydroxyaminoesters would represent an attractive radiosynthesis of [18F]fluoroaminoesters (Figure 1). Methods The newly proposed deoxyfluorination reaction was investigated from a series of readily obtained β‐hydroxyaminoesters derived from serine, α‐methylserine or b‐ phenylserine. Those precursors were treated first with triflic anhydride in the presence of DIPEA to generate in situ the aziridinium by anchimeric assistance, then with [18F]‐fluoride. [18F]KF/K222 and [18F]TBAF were tested as [18F]fluoride reagent. Radioactive products were identified by coelution with reference compounds on analytical HPLC. RCYs were determined by semi‐preparative HPLC. Results The efficacy and the regioselectivity of the reaction were found to be highly dependent on the nature of precursors. The optimal radiochemical yields (40‐70%) were obtained from serine and a‐methylserine precursors bearing a N,N‐ dibenzyl or N‐benzyl‐N‐methylamine function, and the approach was found to be totally regioselective, leading exclusively to β‐aminoesters. In the phenylserine series, a mixture of both α and β isomers was obtained and radiochemical yields were in the 17‐30% range. Results were similar whatever the reaction temperature (rt or 90°C), and the radiofluorination reaction did not progress after 15 min. Conclusion Our results demonstrated the proof of concept of the deoxyradiofluorination methodology for the radiosynthesis of [18F]fluoroaminoesters from serine derivatives at room temperature. The ready access to the hydroxyl precursors as well as the very mild reaction conditions made the approach useful and promising in the field of radiochemistry using fluorine‐18.
Mmarine Morlot; Fabienne Gourand1; Cecile Perrio2 1
CYCERON ISTCT/LDM‐TEP, France; 2 Cyceron, France
RE FER EN CES 1. C. Huang, J. McConathy, Curr. Topics Med. Chem. 2013, 13, 871‐891.
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2. for example: R. N. Krasikova, O. F. Kuznetsova, O. S. Fedorova, Y. N. Belokon, V. I. Maleev, L. Mu, S. Ametamey, P. A. Schubiger, M. Friebe, M. Berndt, N. Koglin, A. Mueller, K. Graham, L. Lehmann, L. M. Dinkelborg, J. Med. Chem. 2011, 54, 406‐410. 3. for example: W. Qu, Z. Zha, K. Ploessl, B. P. Lieberman, L. Zhu, D. R. Wise, C. B. Thompson, H. F. Kung, J. Am. Chem. Soc. 2011, 133, 1122‐1133. 4. for example: a) W. Yu, J. McConathy, L. Williams, V. M. Camp, E. J. Malveaux, Z. Zhang, J. J. Olson, M. M. Goodman, J. Med. Chem. 2010, 53, 876–886; b) N. Jarkas, R. J. Voll, L. Williams, V. M. Camp, M. M. Goodman, J. Med. Chem. 2010, 53, 6603‐6607; c) L. Wang, W. Qu, B. P. Lieberman, K. Plössl, H. F. Kung, Nucl. Med. Biol. 2011, 38, 53‐62; e) C. Huang, L. Yuan, K. M. Rich, J. McConathy, Nucl. Med. Biol. 2013, 40, 498‐506. 5. a) F. Basuli, H. Wu, Z.‐D. Shi, B. Teng, C. Li, A. Sulima, A. Bate, P. Young, M. McMillan, G. L. Griffiths, Nucl. Med. Biol. 2012, 39, 687‐696; b) C. Schjoeth‐Eskesen, P. R. Hansen, A. Kjaer, N. Gillings, ChemistryOpen 2015, 4, 65‐71. 6. a) X. Huang, W. Liu, H. Ren, R. Neelamegam, J. M. Hooker, J. T. Groves, J. Am. Chem. Soc. 2014, 136, 6842‐6845; b) M. B. Nodwell, H. Yang, M. Čolović, Z. Yuan, H. Merkens, R. E. Martin, F. Bénard, P. Schaffer, R. Britton, J. Am. Chem. Soc. 2017, 139, 3595‐3598. 7. a) M. Médoc, F. Sobrio, RSC Adv. 2014, 4, 35371–35374; b) M. Médoc, F. Sobrio, J. Org. Chem. 2015, 80, 10086–10097.
Poster Cate gory: Radiochemistry ‐ 18 F P-017 | An improved synthesis of 4‐(4‐[F‐18] fluorophenyl)piracetam, a PET agent for Parkinson's disease David Blevins1; Murthy Akula2; George Kabalka3; Dustin Osborne4 1
The University of Tennessee, GSM, United States; 2 University of
Tennessee Medcial Center, United States; 3 University of Tennessee Medical Center, United States; 4 The university of Tennessee Medical Center, United States
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Objective Racetams are pyrrolidin‐2‐one based nootropic drugs that are cyclic derivatives of GABA. These agents are known to restore cell membrane fluidity1,2 and are used as cognitive enhancers and to treat dementia. We have previously reported 4‐(4‐[18F]fluorophenyl)piracetam3, 1, as a potential brain imaging agent, by radiofluorodeboronation of the boronate ester 2 followed by ammonolysis. However, the over‐all radiochemical yield was 11% in two steps. We wish to report an improved synthesis of this tracer 1 by radiofluorodestannylation of the new tin precursor 5. Methods The boronate ester 2 was converted to potassium trifluoborate 3 in quantitative yield by reacting the ester with KHF2 in a mixture of methanol and water. The potassium trifluoborate 3 was conveniently converted to the iodo‐compound 4 using ferric chloride and sodium iodide in acetonitrile following the procedure developed in our laboratory.4 Palladium catalyzed deiodostannylation of 4 resulted in the key precursor 5 for radiofluorination. Copper promoted5 radiofluorination of the tin precursor 5 using a mixture of KOTf, K2CO3, Cu (OTf)2 and pyridine in DMA at 130°C for 30 min followed by ammonolysis with NH4OH afforded the title compound 1 in 24% yield. Results Cyclotron produced [18F]fluoride (~100 mCi) was trapped on a QMA cartridge and eluted into a reaction vessel with a mixture of KOTf‐K2CO3 solution and thoroughly dried using an automated sequence on the Sofie Elixys Radiochemistry Platform. A mixture of the tin precursor 5 (5.4 mg), Cu (OTf)2 (7.2 mg), and pyridine (12.2 mL) in DMA (1.0 mL) was transferred to the reaction vessel containing anhydrous fluoride. The reaction was carried out for 30 min. at 130°C. The labeled product was passed through a C18 cartridge and was eluted with ethanol (1.0 mL), and intermediate ethyl ester in ethanol was heated with conc. NH4OH (1.0 mL) at 70°C for 12 min to obtain 4‐(4‐[18F]fluorophenyl)piracetam. The crude product was purified by HPLC to obtain the title compound 1 (24.0 mCi) in 24 % radiochemical yield (n = 2).
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Conclusions An improved synthesis of 4‐(4‐[18F]fluorophenyl)piracetam, 1, a potential PET imaging agent for PD has been successfully accomplished in two steps from tin precursor 5. The radiochemical yield was found to be 24% that is two times more than previously reported method. The radiochemical purity was determined to be >95%. The total reaction time was 50 min. ACKNOWLEDGEMENTS We wish to acknowledge the Molecular Imaging and Translational Research Program and University Health Systems, Knoxville, for the support of this research. R EF E RE N C E S 1. Gunal D, et al (2008) J. Clin Pharm Therap, 33, 175. 2. Nakamura K, et al (1994) Eur J Pharm, 4, 257. 3. Blevins D, et al (2015) J Label Compd Radioharm, 60, S256. 4. Blevins D, et al (2015) Tet Lett, 56, 3130. 5. Markaravage, K et al. (2016) Org lett, 18, 5440
Poster Cate gory: Radiochemistry ‐ 18 F P-018 | A novel [18F]fluoride relay reagent for radiofluorination reactions Bo Zhang1; Benjamin Fraser2; Mitchell Klenner3; Zhen Chen4; Steven Liang4; Massimiliano Massi5; Andrea Robinson6; Giancarlo Pascali3 1
Australia's Nuclear Science and Technology Organisation (ANSTO),
Australia; 2 The Australian Nuclear Science and Technology Organisation, Australia; 3 ANSTO, Australia; 4 MGH/Harvard, United States; 5 Curtin University, Australia; 6 Monash University, Australia
Objectives Fluorine‐18 is the most utilized radioisotope in Positron Emission Tomography (PET), but the wide application of fluorine‐18 radiopharmaceuticals is hindered by its challenging labelling conditions. This necessitates production
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at centralized PET centres with highly specialized equipment including cyclotrons, hot cells, synthesizers, and HPLC capabilities, which ultimately limit the availability of fluorine‐18 tracers to those whose production has a large marketing scale (e.g., [18F]FDG). As such, many potentially important leads remain underutilized. Herein, we describe the use of [18F]ethenesulfonyl fluoride (ESF) as a novel radiofluoride relay reagent that allows radiofluorination reactions to be performed in minimally equipped satellite nuclear medicine centres (Figure 1). Methods [18F]ESF was produced from 2,4,6‐trichlorophenylethenesulfonate using a microfluidic system and was stored on inert cartridges. The cartridges could be shipped remotely where trapped [18F]ESF was liberated by chosen solvent to a vial containing precursor and additives. The reaction mixture was then stirred and heated using a heating block. Reaction conditions including temperature, time, precursor concentration, and additives were optimised, and the radiochemical yields (RCYs) were compared with those for traditional [18F]fluoride method. Results We found that conditions of 1 mg/mL precursor, 0.5 mg/ mL tetraethylammonium bicarbonate as additive, temperature of 100°C, and time of 15 min were useful to assess radiofluorination scope on commercially available precursors. The obtained RCYs were compared with those generated from traditional dried [18F]fluoride source and no statically significant difference was observed for most precursors. Some differences on RCYs, both positive and negative, were noted when novel type of precursors (i.e., boronic acids, iodonium ylides) were tested. Conclusions We have developed a method to perform radiofluorinations using a new radiofluoride relay reagent, [18F] ESF. Such method reduces the reaction equipment needed, in the simplest case to a simple heating block, single‐use vials and magnetic stir bar. Notably, this new process is not only compatible with typical commercial precursors, but also feasible to accommodate emerging precursors with novel leaving groups.
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ACKNOWLEDGMENTS Financial supports from Monash University (MGS and MIPRS) and The Australian Institute of Nuclear Science and Engineering (AINSE PGRA 12074) are gratefully acknowledged.
Poster Cate gory: Radiochemistry ‐ 18 F
P-019 | An improved method for preparing [18F]AV‐45 using solid‐phase extraction purification Lifang Zhang1; Yan Zhang1; Futao Liu1; Xinyue Yao1; Zhihao Zha2; Yajing Liu3; Jinping Qiao1; Lin Zhu4; Hank Kung2 1
College of Chemistry, Beijing Normal University, China; 2 University of
Pennsylvania, United States; 3 Beijing Institute of Brain Disorders, Capital Medical University, China; 4 Beijing Normal University, China
Objectives Alzheimer's disease (AD) is a neurodegenerative disease with a very significant social impact in aging population.1 Accumulation of Aβ in the brain is one of the major factors in driving AD pathogenesis. [18F]AV‐45 (florbetapir f18, Amyvid) is the first 18F‐labeled PET imaging agent targeting β‐amyloid plaques for the diagnosis of AD approved by FDA. It is now being used for patient selection prior to enrollment in drug trials specifically designed to reduce the accumulation of β‐amyloid plaques in the brain.2 In this preliminary work, instead of using HPLC purification, we proposed to take advantage a rapid and simple solid‐phase extraction (SPE) purification method for preparation of [18F]AV‐45.3 However, one of the main issues in using this SPE purification method was that the main chemical impurity, predominantly a hydroxyl derivative (AV‐136), cannot be completely removed. We report herein an optimization of
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SPE purification method for preparation of [18F]AV‐45 to remove the majority of chemical impurities. Methods Radiosynthesis of [18F]AV‐45 was first initiated by azeotropic distillation with acetonitrile to obtain activated [18F]KF/K222, after a nucleophilic substitution reaction with tosylate precursor (1 mL DMSO, 110, 120, 130, or 140°C), followed by acid hydrolysis (1 mL 3 M HCl or 1 mL 2 M H2SO4 acid solutions, 100°C) and neutralization. The crude product was passed through an Oasis cartridge (3cc, Waters), and the cartridge was rinsed with water (10 mL × 2). Then the Oasis cartridge was eluted with increasing concentration of ethanol (EtOH/water, 10%‐70%) and acetonitrile (ACN/water, 10%‐50%), respectively. Next, increasing volume of optimal combination of eluent (ACN/water or EtOH/water) to wash the cartridge was carried out. Finally, we also identified and quantified residual chemical impurities in the product by using LC/MS analysis and estimated quantity presenting in each HPLC peak by comparing with standard curves. Results As shown in Figure 1 (B, C), a majority of the pseudo‐carrier, AV‐136, was removed with ACN/water, while retaining the desired product, [18F]AV‐45. In order to make the SPE purification more efficient, we explored the optimal combination of eluent using EtOH/water or ACN/water (Figure 1D and 1E). The optimal elution conditions for SPE purification was identified as washing Oasis cartridge with 6 mL of 35% ACN/water (Figure 1D and 1E). With this SPE purification method, more than 95% of AV‐136 was removed, while the loss of the desired product, [18F]AV‐45, was minimized to less than 10%. There were two other chemical impurities remaining in the SPE‐purified product: 4 and 5 (Figure 1A). Under optimized conditions, the remaining two impurities, 4 and 5, were reduced. In summary, we have optimized and purified the desired, [18F]AV‐45, by using SPE purification via Oasis cartridge. Under an optimized condition, the remaining pseudo‐carrier, AV‐136, in the final product was 13.2 ± 1.2 μg (n = 3); the amount of impurity 4 was 3.4 ± 0.9 μg (n = 3), and the amount of impurity 5 was about 3.0 ± 2.5 μg (n = 3). It was observed that after the optimal SPE purification a total amount of chemical impurities remaining in the final product vial was less than 30 μg. Conclusions A rapid and simple SPE purification method for [18F]AV‐ 45 preparation was developed to remove majority of chemical impurities. This simplified preparation may be suitable for routine preparation in clinical studies. ACKNOWLEDGEMENTS This work was supported in part by grants from the National Key Research and Development Program of China (2016YFC1306300) and Beijing Science and Technology Project (Z151100003915116).
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R EF E RE N C E S 1. Choi SR, Golding G, Zhuang Z, et al. Preclinical properties of 18F‐ AV‐45: a PET agent for Aβ plaques in the brain. J Nucl Med. 2009;50(11):1887‐1894. 2. Zhu L, Ploessl K, Kung HF. PET/SPECT imaging agents for neurodegenerative diseases. Chem Soc Rev. 2014;43(19):6683‐6691. 3. Liu Y, Zhu L, Ploessl K, et al. Optimization of automated radiosynthesis of [18F]AV‐45: a new PET imaging agent for Alzheimer's disease. Nucl Med Biol. 2010;37(8):917‐925.
Poster Cate gory: Radiochemistry ‐ 18 F P-020 |
18
F labeled pyrrolopyrimidine derivatives targeting LRRK2 for evaluation of Parkinson's disease Xueyuan Chen; Zhaobiao Mou1; Yunming Zhang1; Hongzhang Yang1; Zijing Li2; Fang Xie3 1
Center for Molecular Imaging and Translational Medicine, State Key
Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, China; 2 Xiamen University, Center for Molecular Imaging and Translational Medicine, China; 3 PET Center, Huashan Hospital, Fudan University, China
Objectives Clinical PET imaging diagnose of Parkinson's diseases relies on monitoring pathological changes such as levels of dopamine, glucose metabolism, neuroinflammation, which are reflecting disease progression indirectly. Mutations associated with leucine‐rich repeat kinase 2 (LRRK2) gene are the main cause of Parkinson's disease (PD). However, no radiotracer targeting LRRK2 has been developed to study the changes of LRRK2 expression for diagnosing Parkinson's diseases until now. Therefore, the aim of this study was to develop a 18F tracer based on PF‐06447475[1] for diagnosing PD with LRRK2 mutations and to study the occurrence and development of PD by PET imaging. Methods This novel LRRK2 radiotracer was designed by modifying cyanophenyl group into 2‐bromopyridine, and 18F was
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introduced by halogen nucleophilic substitution. The synthesis of precursor was achieved from 4‐chloro‐5‐iodo‐[2,3‐ d]pyrimidine by substituting morpholine for chlorine and Suzuki coupling reaction. After confirming the structure, we used classically cryptand in combination with potassium carbonate is the aminopolyether Kryptofix 2.2.2. complex.[2] 18F‐(2‐10 mCi, approximately 10μL) was added into the glanded reaction bottle containing 1.0 mg/mL precursordissolved in DMSO(100 μL). The reaction was at 150°C for 15 minutes; after extracting and concentrating, the residue was purified via semipreparative RP‐HPLC. Results The chemical yields of precursor 1 and its reference compound were 54.8% and 68.2%, respectively. The radiotracer [18F]1 was prepared from nucleophilic substitution reaction and analyzed by RP‐HPLC with 15‐20% radiochemical yield. The reaction time was no more than 30 minutes. Precursor 1 and its reference compound have different retention time, which demonstrate easily to separated by HPLC. Conclusions A novel 18F labeled compound has been successfully developed, which was obtained easily by simple chemical synthesis and traditional labeling method. This compound can be developed as potenial PET probe to diagnose PD. ACKNOWLEDGMENTS This work was supported by the National Science Foundation of China (81501534).
Poster Cate gory: Radiochemistry ‐ 18 F P-021 | Automated radiosynthesis of 2‐[18F] BTSO2CF2H in a GE FASTLab synthesizer Agostinho Lemos1; Laura Trump2; Bénédicte Lallemand3; Patrick Pasau3; Joël Mercier3; Christophe Genicot3; Christian Lemaire4; Andre Luxen5 1
University of Liège, Belgium; 2 Global Chemistry, UCB New medicines,
UCB Biopharma SPRL, Belgium; 3 Global Chemistry, UCB NewMedicines, UCB Biopharma SPRL, Belgium; 4 GIGA Cyclotron Research Centre In Vivo Imaging, University of Liège, Belgium; 5 Universite De Liege, Belgium
Objectives Fluorine‐18 is the one of most commonly used radionuclide for posítron emission tomography (PET). The relevance of noninvasive PET as a molecular imaging tool for in vivo quantification of biochemical and physiological processes, for assessment of disease state, and for drug development has caused a great demand for novel approaches for installation of fluorine‐18 and other relevant motifs (eg, CHF18F). Despite the recent advances in difluoromethylation of organic substrates, only a few methodologies for the preparation of
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CHF18F‐containing ligands have been reported.1 Inspired by the previous works describing the use of 2‐BTSO2CF2H in the photoinduced difluoromethylation of substrates,2 we opted to synthesize 2‐[18F]BTSO2CF2H ([18F]1) as a potential novel reagent for introduction of CHF18F groups on new PET ligands under photoredox conditions. Methods A fully automated and multi‐step radiosynthesis of [18F]1 was performed in a GE FASTlab synthesizer in conjunction with an additional high performance liquid chromatography (HPLC) purification procedure. Results Low activity labeling tests were performed to determine the feasibility of the radiosynthesis of [18F]1. Several parameters regarding the elution of fluorine‐18 from a quaternary methyl ammonium (QMA) cartridge, the solvents and temperature implemented in the introduction of fluorine‐18, the amount of precursor, and the reaction time seemed to influence the efficiency of the radiochemical synthesis. The fully automated radiosynthesis of [18F]1 at high level of starting radioactivity in conjunction with HPLC purification and formulation was performed in 60 min. After HPLC purification, the isolated compound [18F]1 was obtained in 3.5 ± 0.5% RCY (decay‐corrected) with a high radiochemical purity (RCP > 99%), and with a molar radioactivity of 81 ± 11 GBq/μmol (decay‐ corrected). A slight decrease of the RCP of [18F]1 was observed after the end‐of‐synthesis (EOS). Conclusions We reported the development of a very promising CHF18F‐ containing reagent that will enable the access to novel radiotracers and radiopharmaceuticals potentially useful for PET imaging. In collaboration with UCB, the reagent is currently being implemented in visible light photoredox‐catalyzed 18 F‐difluoromethylation of N‐containing heteroarenes of medicinal interest. This work also evidenced the importance of automating a radiochemical synthesis in the circumvention of potential radioprotection issues especially with multiple GBq of starting radioactivity. ACKNOWLEDGEMENTS This work was supported by funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement N°675071 (ISOTOPICS). RE FER EN CES 1. (a) Org. Lett., 2013, 15, 2648‐2651; (b) Angew. Chem. Int. Ed., 2015, 54, 9991‐9995; (c) Synlett, 2016, 27, 25‐28; (d) Angew. Chem. Int. Ed., 2016, 55, 1‐6; (e) Chem. Commun., 2017, 53, 126‐129; (f) Org. Lett., 2017, 19, 568‐571. 2. (a) Angew. Chem, Int. Ed. 2016, 55, 2743‐2747; (b) Chem. Commun. 2016, 52, 13413‐13416; (c) Org. Biomol. Chem. 2017, 15, 8748‐8754; (d) Org. Biomol. Chem. 2017, 15, 9057‐9060.
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Poster Cate gory: Radiochemistry ‐ 18 F P-022 | Rapid and chemoselective ligation of hydroxylamine‐functionalized biomolecules with [18F]6‐fluoronicotinoyltrifluoroborate at room temperature Hazem Ahmed1; Aristeidis Chiotellis2; Christopher White1; Thomas Betzel1; Sara Da Ros1; Roger Schibli1; Jeffrey Bode1; Simon Ametamey3 1
ETH Zurich, Switzerland; 2 NCSR Demokritos, Greece; 3 Radiopharmacy,
ETH Zurich, Switzerland
Objectives Fluorine‐18 labeling of large biomolecules such as peptides, proteins, and antibodies is generally accomplished via a multi‐step reaction sequence using a prosthetic group. The prosthetic group has to satisfy several requirements including high 18F incorporation and fast coupling to the target
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biomolecule under mild conditions. Recently, a biorthogonal, fast, and quantitative amide‐forming ligation of potassium acyltrifluoroborates (KATs) and O‐ carbamoylhydroxylamines has been reported.1 As part of our efforts to develop a fluorine‐18 labeling strategy for large biomolecules under mild conditions, we explored a series of [18F]F‐KATs and used the best performing KAT codenamed [18F]FN‐KAT (6‐fluoronicotinoyltrifluoroborate) for ligation reactions with biomolecules of different molecular sizes. Methods Four different pyridine KATs were radiolabeled with 18F via nucleophilic aromatic substitution reaction using either a bromo or a nitro leaving group. The reactions were carried out in DMSO with and without the additive, 1,4‐ diazabicyclo[2.2.2]octane, (DABCO), which was recently reported to enhance 18F incorporation of 2‐halopyridines.2 For the purification of the fluorine‐18 labeled KATs, a series of solid phase extraction cartridges and HPLC conditions were evaluated. The KAT with the best radiochemical yield was selected for the ligation reactions. Conjugation efficiency was validated using hydroxylamine functionalized model compounds that include a small molecule, a peptide, and super‐folder green fluorescent protein (S147C) modified with His‐tag [sfGFP(S147C)‐His].3 Results From the list of the four KATs tested, [18F]FN‐KAT (Scheme 1) provided the highest radiochemical yield using DABCO as an additive. Near quantitative radiochemical yield of 96% was achieved for [18F]FN‐KAT. The best trapping efficiency was obtained using HLB Plus cartridge and HPLC purification was accomplished using 10 mM aqueous potassium acetate and MeCN (73:27) as eluent to afford greater than 95% radiochemical purity for [18F]
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FN‐KAT. Contrary to our expectations, no 18F‐19F isotopic exchange was observed, and molar activity ranged from 43‐152 GBq/μmol. The coupling of [18F]FN‐KAT to hydroxylamine functionalized but otherwise fully unprotected peptide as well as folded [sfGFP(S147C)‐His] was accomplished in quantitative radiochemical yields at room temperature after a reaction period of 15 min (Scheme 1). Conclusion A very promising chemoselective ligation reaction with [18F]FN‐KAT has been achieved. The method allows the rapid radiofluorination of small and large complex molecules in quantitative radiochemical yields at room temperature without the need to protect functional groups. ACKNOWLEDGEMENTS This project was supported by ETH Research Grant ETH‐ 44 17‐2. R EF E RE N C E S 1. Noda H, Erős G, Bode JW. Rapid Ligations with Equimolar Reactants in Water with the Potassium Acyltrifluoroborate (KAT) Amide Formation. Journal of the American Chemical Society. 2014;136(15):5611‐5614. 2. Naumiec GR, Cai L, Lu S, Pike VW. Quinuclidine and DABCO Enhance the Radiofluorination of 5‐Substituted 2‐Halopyridines. European Journal of Organic Chemistry. 2017;2017(45): 6593‐6603. 3. White CJ, Bode JW. PEGylation and Dimerization of Expressed Proteins under Near Equimolar Conditions with Potassium 2‐ Pyridyl Acyltrifluoroborates. ACS Central Science. 2018;4(2): 197‐206.
Poster Cate gory: Radiochemistry ‐ 18 F P-023 | BF3‐Gln‐C2 as a stable 18F‐labeled glutamine derivative for imaging tumor Junyi Chen; Cong Li; Jiyuan Li; Zhibo Liu Peking University, China
Objective Both glutaminolysis and glycolysis are important metabolisms in the tumor cell. People now definitely affirm that tumor cell use glycolysis to produce not only energy but also metabolic intermediates for tumor rapid growth. For the tumor with glucose‐addiction, [18F]FDG as the glucose derivative has been developed for many years and did well. There is not a widely used F‐18 labeled Gln probe. Although [18F]4‐FGln by Hank F. Kung[a] or [18F]Gln‐ BF3 by Zhibo Liu[b] shows great tumor imaging and
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application potential, what should not be ignored is that both of them are unstable and defluorinate rapidly, which bring inconvenience during clinical research. So as to develop a more stable Gln probe, we modified the structure of [18F]Gln‐BF3 and obtain [18F]Gln‐BF3‐C2, which can be labeled by the kit‐like way, be stable and be high tumor uptake. Method Based on possible unstable mechanisms through a 5‐membered or 6‐membered transition state, [18F]Gln‐ BF3‐C2, two more carbon atoms with [18F]Gln‐BF3 was synthesized. Same with other BF3 probes, [18F]Gln‐BF3‐ C2 can be labeled with 40% RCY by using HPLC‐free aqueous 18F‐19F isotope exchange. In vitro stability was tested in 37°C PBS for 2 hours. So as to compare the stability in vivo, we did the biodistribution and PET imaging of [18F]Gln‐BF3 and [18F]Gln‐BF3‐C2 in Nu/Nu mice, especially in kidney and bone. The PET/CT imaging of [18F] Gln‐BF3‐C2 was done in mice bearing BGC823 or 4T1 xenografts, which was compared with [18F]4‐FGln and [18F]Gln‐BF3. Results [18F]Gln‐BF3‐C2 shows great stability and no obvious defluorination for 2 hours in PBS. Through the biodistribution and PET imaging, two more carbon atoms decreased the bone uptake markedly. The decreased uptake of kidney implied [18F]Gln‐BF3‐C2 was lower hydrophilic and with better pharmacokinetics. PET imaging showed high contrast (tumor/muscle >3) of [18F]Gln‐BF3‐C2 uptake in 4T1 and BGC823, which was no tumor uptake of [18F]Gln‐BF3. We compared the PET imaging of [18F]Gln‐BF3‐C2 and [18F]4‐FGln; [18F]Gln‐BF3‐C2 showed higher tumor uptake and clean background. Conclusion We succeeded in synthesis [18F]Gln‐BF3‐C2, a more stable Gln PET probe, and it showed remarkable stability in vitro and in vivo. It can be cleared rapidly and shows high contrast for PET imaging in mice bearing BGC823 or 4T1 xenografts. [18F]Gln‐BF3‐C2 was a potential clinical Gln probe on account of its stability and high tumor contrast. ACKNOWLEDGEMENTS We acknowledge support from the National Natural Science Foundation of China and people from Peking Union Medical College Hospital. RE FER EN CES 1. [a] Lieberman B P, et al. PET Imaging of Glutaminolysis in Tumors by 18 F‐(2S, 4R) 4‐Fluoroglutamine. The Journal of Nuclear Medicine, 2011, 52(12): 1947. [b] Li C, et al. Preclinical study of an 18F‐labeled glutamine derivative for cancer imaging. Nuclear medicine and biology, 2018, 64: 34‐40.
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Poster Cate gory: Radiochemistry ‐ 18 F
1
P-024 | One‐step synthesis of [18F]MC225
Objectives [18F]MC225 [5] is a radiopharmaceutical for imaging P‐ glycoprotein (P‐gp) function at the blood‐brain barrier.1 Dysfunction of P‐gp can lead to the onset of several neurodegenerative diseases such as Alzheimer or Parkinson.2,3 For the evaluation of [18F]MC225 in clinical studies, a
intended for GMP compliant productions Lara Garcia Varela; Khaled Attia; Ines Antunes1; Chantal Kwizera; Astrid Niezink; Rolf Zijlma; Ton Visser; Rudi Dierckx1; Philip Elsinga2; Gert Luurtsema2
UMCG, Netherlands; 2 University Medical Center Groningen,
Netherlands
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reliable fully automated GMP compliant synthesis is needed. Recently, [18F]MC225 was produced via two steps synthesis, including distillation of [18F] 4 fluorethylbromide. This synthesis is rather complex and involves a time‐consuming procedure with relatively low radiochemical yields. Therefore, our aim is to develop a one‐step synthesis to produce [18F]MC225 in order to make the reaction easier, faster, and more robust. Moreover, we set the appropriate conditions for the automation of the one‐step synthesis for GMP production. Methods The one‐step synthesis method required the development of a new precursor that allows us to achieve the [18F] MC225 via direct fluorination. Therefore, the mesylate precursor [4] was synthesized from the phenol compound [1] according to the reaction scheme (Figure 1) in 3 steps. The automated synthesis was performed using Eckert & Ziegler modular‐lab cassette based units. Optimization of the synthesis was performed to find appropriate conditions. The crude reaction mixture was purified with preparative HPLC using NaOAc/ACN (5.5:4.5) (v/v) as eluent and a Symmetry shield RP8 5 μM 7.8 × 300 mm column at a flow of 3 ml/min. The formulation and quality control were performed as described in the literature.1 Results: The desired mesylate precursor [4] was successfully synthesized in practical yields. The addition of a good leaving group to the phenoxyethanol [3] affected the stability of the compound. However, it was found that by attaching methanesulfonic anhydride to the mesylate precursor,[4] the stability was substantially improved via a salt formation. The optimal conditions for the radiosynthesis were obtained using a mixture of [18F] Fluoride, K2CO3, and Kryptofix222 dried in ACN at 130°C for 15 min, otherwise decreases in the radiochemical yield occurred. Afterwards, the mesylate precursor
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[4] dissolved in DMF was added and heated in a closed vial at 140°C for 15 min, resulting in TLC‐confirmed conversion of 20% from [4] to [5]. The reaction mixture was pre‐purified using alumina cartridge and transferred to a preparative HPLC. After purification and formulation, the quality control confirmed that the product was obtained in a radiochemical yield of 8%, corrected for decay. The radiochemical purity was 98%, and average molar activity >25.000 GBq/mmol (n = 3). The average synthesis time was 77 min (n = 3) including purification and formulation. Conclusions [18F]MC225 was successfully produced via one‐step synthesis using the mesylate precursor [4]. This procedure allows us to automate the process on commercially available synthesis modules and perform the radiosynthesis under GMP conditions. Further optimization is ongoing to increase the radiochemical yield.
RE FER EN CES 1. Savolainen H, Windhorst AD, Elsinga PH, et al. Evaluation of [18F]MC225 as a PET radiotracer for measuring P‐glycoprotein function at the blood–brain barrier in rats: Kinetics, metabolism, and selectivity. J Cereb Blood Flow Metab. 2017;37:1286‐1298. 2. Löscher W, Potschka H. Role of drug efflux transporters in the brain for drug disposition and treatment of brain diseases. Prog Neurobiol. 2005;76:22‐76. 3. Kannan P, John C, Zoghbi SS, et al. Imaging the Function of P‐ Glycoprotein With Radiotracers: Pharmacokinetics and In Vivo Applications. Clin Pharmacol Ther. 2009;86:368‐377. 4. Savolainen H, Cantore M, Colabufo NA, Elsinga PH, Windhorst AD, Luurtsema G. Synthesis and Preclinical Evaluation of Three Novel Fluorine‐18 Labeled Radiopharmaceuticals for P‐ Glycoprotein PET Imaging at the Blood‐Brain Barrier. Mol Pharm. 2015;12:2265‐2275.
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Poster Cate gory: Radiochemistry ‐ 18 F P-025 | Development of scandium‐catalyzed N‐[18F]fluoroalkylation of aryl and heteroaryl amines with [18F]epifluorohydrin Masayuki Fujinaga1; Takayuki Ohkubo2; Katsushi Kumata3; Nobuki Nengaki2; Ming‐Rong Zhang3 1
Department of Radiopharmaceuticals Development, National Institute of
Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2 SHI Accelerator Service, Japan; 3
Department of Radiopharmaceutics Development, National Institute of
Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
Objectives [18F]Fluoroalkylation is a useful method for introduction of fluorine‐18 into molecules containing NH, OH, and SH‐groups. Using various [18F]fluoroalkylating agents, we are routinely producing clinically‐useful 18F‐radiotracers, such as [18F]FMeNER‐d2, [18F]FEDAA1106, [18F]FEDAC, [18F]FE‐SPARQ, and [18F]FEtPE2I. Recently, we have reported a convenient [18F] fluoroalkylation route for introducing 3‐[18F]fluoro‐2‐ hydroxypropyl ([18F]FHP) group into a targeted molecule via ring‐opening reaction of [18F]epifluorohydrin ([18F]2) with phenol analogs by using an automated synthesis system.1 However, despite the usefulness of epifluorohydrin in organic chemistry, the reaction of [18F]2 with low nucleophilic reagents, such as aromatic amine has rarely been reported. To extend application of this technique, in this study, we developed a simple method for introducing [18F]FHP group into aryl or heteroaryl amines in the presence of Sc(OTf)3. Methods Unlabeled 3a‐n were prepared by reactions of aryl or heteroaryl amines with epifluorohydrin in the presence of Sc(OTf)3 at moderate chemical yields (40‐84%). [18F]2 was synthesized by the reaction of glycidyl tosylate 1 (10 mg) and [18F]KF/K2.2.2 in 1,2‐dichlorobenzene at 130°C for 2 min and immediately transferred by distillation into a reaction vial including aromatic amine in CCl4. The reaction conditions for the N‐[18F]fluoroa‐
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lkylation of p‐anisidine as a model compound with [18F]2 were optimized with regard to solvents, temperatures, and times. Under the optimized conditions, [18F]3a‐n were synthesized by the reaction of various aryl or heteroaryl amines and [18F]2. Radiochemical conversions (RCCs) were determined by radio‐HPLC for these reaction mixtures. Results First, a suitable solvent for N‐[18F]fluoroalkylation of p‐anisidine with [18F]2 in the presence of Sc(OTf)3 (10 mol%) was examined. In coordinating solvents such as THF and DMF, the reaction did not effectively proceed. On the other hand, the reaction efficiency was significantly increased by the use of nonpolar solvent such as CCl4. Under several temperatures and times investigated, the reaction performed in CCl4 at 50°C for 20 min was found to give the best [18F]fluoroalkylating result. According to the optimized conditions, [18F]3a was synthesized by reaction of p‐anisidine and [18F]2 using an automated synthesis system. By purification for the reaction mixture with semi‐preparative HPLC and formulation, [18F]3a was obtained with a synthesis time of 85 ± 3 min and 27% radiochemical yield (isolated‐yield based on the cyclotron‐produced [18F]F‐). To demonstrate suitability of this method, [18F]3b‐n were synthesized from various aryl or heteroaryl amines containing halogen, alkyl, acetyl, or hydroxyl groups. Radio‐HPLC analyses for the reaction mixtures indicated that [18F]3b‐l and [18F]3m‐n were yielded in 25–69% and 6–16% RCCs, respectively. Using 2,2,2‐ trifluoroethanol (TFE) as a co‐solvent, N‐[18F] fluoroalkylation of aryl amines proceeded more effectively to give the corresponding product [18F]3b‐l in 30–98% RCCs. Conclusion Scandium‐catalyzed N‐[18F]fluoroalkylation with [18F]2 allowed facile introduction of [18F]FHP group into aryl or heteroaryl amines under mild conditions. Next, we will focus on improving efficiency for the N‐[18F] fluoroalkylation of heteroaryl amines.
RE FER EN CES 1. M. Fujinaga, T. Ohkubo, T. Yamasaki, et al. ChemMedChem. 2018, 13, 1723–1731.
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Poster Cate gory: Radiochemistry ‐ 18 F P-026 | Ruthenium‐mediated 18F‐fluorination of phenols at Turku PET Centre Noora Rajala; Salla Lahdenpohja; Anna Kirjavainen Turku PET Centre, University of Turku, Finland
Objectives Transition metal‐mediated 18F‐fluorination has been a hot topic in PET‐radiochemistry over the last years with the most recent studies in Ru‐mediated 18F‐fluorination.1,2 At Turku PET Centre, we have applied Ru‐mediated 18F‐fluorination reactions to practice with several small molecules (3‐ [18F]fluoropyridine, 1‐[18F]fluoro‐4‐iodobenzene, 1‐[18F] fluoro‐4‐nitrobenzene and 4‐[18F]fluorobenzonitrile). Methods Ru‐complex and Ru‐phenol‐complex were synthetized as previously reported.1 Formation of Ru‐phenol‐complex was followed with MS. Radiolabeling was performed with a semi‐automated synthesis device roughly following a previously published synthesis method.1,2 The synthesis protocol is presented in Fig 1. Cyclotron produced [18F] fluoride was dried either by azeotropic distillation with MeCN or by solid phase extraction (SPE). With SPE, [18F]fluoride was trapped into a 45 mg PS‐HCO3‐ SPE cartridge (Synthra, Germany). The cartridge was washed with MeCN and [18F]fluoride was eluted with a mixture of Ru‐phenol‐complex and chloroimidazolium chloride (Im‐Cl) in 1:1 DMSO:MeCN mixture into the reaction vessel. The reaction was heated at 125°C for 60 min and samples for analytical radio‐HPLC were collected at 10, 30, and 60 minutes. Radiochemical yields (RCY) are non‐decay corrected and are based on the HPLC analysis of the crude product. Figure 1. Ru‐mediated synthesis of [18F]arylfluorides. Results Ru‐phenol‐complex formations were successful. [18F] Fluoride was effectively dried by azeotropic distillation or by SPE (elution efficiency of up to 60 %). Radiochemical yields (RCY) varied from poor to excellent as follows: 1‐[18F]fluoro‐4‐nitrobenzene RCY 80 % after 10 min reaction, 3‐[18F]fluoropyridine RCY 1.5 % after 30 min reaction, 1‐[18F]fluoro‐4‐iodobenzene RCY 10 % after 30 min
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reaction and 4‐[18F]fluorobenzonitrile RCY 90 % after 30 min reaction. Conclusions For our experience, Ru‐mediated fluorination is suitable method to label phenols containing a strong electron withdrawing group. Reactivity scope is variable. In the future, our aim is to synthetize clinically interesting structures via Ru‐mediated 18F‐labeling. ACKNOWLEDGMENTS This work was supported by the Academy of Finland (grant no. 307924). RE FER EN CES 1. Beyzavi et al. ACS Cent. Sci. 2017, 3, 944 2. Rickmeier and Ritter, Angew. Chem. Int. Ed. 2018, 57, 14207
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-027 | Development of a new 18F‐labeled radioligand for imaging sigma2 receptors by positron emission tomography Friedrich‐Alexander Ludwig1; Steffen Fischer2; Rares Moldovan3; Winnie Deuther‐Conrad; Mathias Kranz; Dirk Schepmann4; Hongmei Jia5; Bernhard Wünsch; Peter Brust6 1
Department of Neuroradiopharmaceuticals, Research Site Leipzig,
Helmholtz‐Zentrum Dresden‐Rossendorf, Institute for Radiopharmaceutical Cancer Research, Germany; 2 HZDR, FS Leipzig, Germany; 3 Helmholtz‐Zentrum Dresden Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 4 Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Germany; 5 Beijing Normal University, China; 6 Helmholtz‐Zentrum Dresden‐Rossendorf, Germany
Objectives Sigma2 receptors (S2R) have been found in CNS, liver, kidney, as well as endocrine glands and are suggested to play important roles in the regulation of cell differentiation. Besides their overexpression in various tumor cell lines, derived from, eg, breast, brain, colon, lung, pancreas, and prostate, they show a 10‐fold higher expression
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in the proliferating vs quiescent status and thus are possible markers of solid tumor's proliferative status. To quantify the S2R availability in living subjects, we aim for the development of a new class of S2R ligands that could be labeled by fluorine‐18. Methods Starting from structural motifs known for S2R ligands,1,2 we modified the indole ring system in A and synthesized a novel series of fluorine containing indole and aza‐indole derivatives (1a‐d and 2‐6 in Fig. 1). Their binding affinities towards sigma2 and sigma1 receptors were determined by radioligand‐binding assays, and 2 was selected for synthesis of a boronic acid pinacol ester precursor for radiolabeling. Synthesis of [18F]2 was optimized starting from 100‐500 MBq of 18F‐fluoride, using Kryptofix (K2.2.2.)/ K2CO3 (0.18‐1.8 μmol/0.04‐0.35 μmol) as well as TBAHCO3 (2.3 and 7.5 μmol) and 2‐4 mg of precursor 7, in the presence of Cu (OTf)2py4 (0.4‐6.8 eq.) in various solvent systems at 80‐135°C, monitored for 5‐20 min. For monitoring, several analytical methods (radio‐UHPLC, ‐HPLC, and ‐TLC) have been established, e.g., on the basis of RP18 und RP8 stationary phases for LC systems. Besides, different techniques for purification and isolation were investigated, including a substitution of semi‐preparative HPLC by time‐ saving cartridge systems. Results By altering the heterocyclic system of A, a small series of fluorinated aza‐indoles was synthesized (Fig. 1), of which 2 showed most promising binding affinity and selectivity (Ki(S2R) = 1.6 nM; Ki(S1R) = 691 nM). Radiosynthesis of [18F]2 was achieved with RCYs in a range of 20‐45% (n = 2, all non‐isolated, radio‐UHPLC)
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by use of 2.0 mg of precursor 7 (4.1 μmol) and 3.6 eq. of Cu (OTf)2py4 at 115°C within 10 min. The reaction was accompanied by the formation of a by‐product (bp), which increased over time. Using the K2.2.2./K2CO3 system resulted in RCYs of 21.5% (bp 5.5%) and 27.7% (bp 4.6%), in DMF and DMA/ n‐BuOH, respectively. Application of TBAHCO3 showed further increased conversions, represented by a RCY of 44.8% (bp 9.1%) in DMA/ n‐BuOH. For subsequent semi‐preparative HPLC, separation conditions were optimized but still lack from low recoveries. As an alternative, SPE procedures using cartridge systems (SiO2, RP18) are being established and could be used as a time saving technique for the isolation of [18F]2. Conclusions The novel S2R‐affine aza‐indole derivative 2 was synthesized and radiofluorination of the appropriate boronic acid pinacol ester precursor afforded [18F]2 in RCYs of up to 45% (non‐isolated). The optimal parameters for the radiosynthesis, conducted in a synthesis automat or module, have to be determined to setup a procedure for the production of [18F]2, which enables detailed preclinical in vitro and in vivo studies of this promising radioligand. ACKNOWLEDGEMENT The authors would like to thank the Deutsche Forschungsgemeinschaft (DFG) for financial support (BR 1360/13‐1).
RE FER EN CES 1. Georgiadis, M.‐O. et al. Molecules 2017, 22, 1408 2. Wang, L. et al. Bioorg. Med. Chem. 2017, 25, 3792‐3802
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Poster Cate gory: Radiochemistry ‐ 18 F P-028 | Investigation of [18F]FESCH for PET imaging of the adenosine A2A receptor in a rotenone‐based mouse model of Parkinson's disease and development of a two‐step one‐pot radiolabeling strategy Susann Schroeder; Thu Hang Lai1; Mathias Kranz; Magali Toussaint1; Qi Shang2; Sladjana Dukic‐Stefanovic; Francisco Pan‐Montojo3; Peter Brust1 1
Helmholtz‐Zentrum Dresden‐Rossendorf, Germany; 2 Ludwig‐
Maximilians‐Universität (LMU) Munich, University Hospital Großhadern, Neurological Clinic, Department of Neurology, Munich (Germany) AND Technische Universität Dresden (TUD), University Hospital Carl Gustav Carus, Clinic of Neurology, Dresden, Germany; 3 Ludwig‐Maximilians‐ Universität (LMU) Munich, University Hospital Großhadern, Neurological Clinic, Department of Neurology, Munich, Germany
Objectives Rotenone‐treated mice are regarded as a model for Parkinson's disease (PD). Increased availability of the adenosine A2A receptor (A2AR) has been found in the striatum of patients with PD and dyskinesias.1 The aim of this study was to investigate whether similar alterations are found in the mouse model of PD using small animal PET/MR imaging. For that purpose, [18F]FESCH 2 was the radiotracer of choice due to its high A2AR specificity and excellent PET imaging properties.2–5 Furthermore, we intended to develop a simplified one‐pot strategy for the radiosynthesis of [18F]FESCH. Methods The published two‐step procedures for the radiosynthesis of [18F]FESCH start with the nucleophilic 18F‐labeling of ethane‐1,2‐diol bis(3,4‐dibromobenzenesulfonate) 4 or ethane‐1,2‐diol bis(4‐methylbenzenesulfonate).2 The respective [18F]fluoroethyl synthon is isolated either by semi‐ preparative HPLC 4 or cartridge 2 and, only then, reacted with the phenol precursor desmethyl SCH442416. In our novel one‐pot approach, desmethyl SCH442416 was treated with 40% TBAOHaq. to generate the activated phenolate, which was directly reacted with the non‐isolated 2‐[18F] fluoroethyl tosylate in MeCN at 120°C for 10 min (see Figure 1). [18F]FESCH was purified by semi‐preparative HPLC, concentrated using solid‐phase extraction on a pre‐ conditioned RP cartridge and eluted with absolute EtOH. After evaporation of the solvent at 75°C, the radiotracer was finally formulated in isotonic saline ready for injection. [18F]FESCH (5.0 ± 1.8 MBq) was administered to C57BL/6JRj mice (control n = 5, rotenone‐treated n = 7, 18 month, 28‐35 g), and whole body scans were performed
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for 60 min in listmode with a Mediso nanoScan® PET/MR scanner followed by dynamic reconstruction. Time‐activity curves (TACs) were generated for regions of interest such as striatum (Figure 1) and cerebellum as reference region. Results The herein described one‐pot strategy provided [18F]FESCH (Ki hA2A=0.6 nM) with an overall radiochemical yield of 16.1 ± 1.5% (n = 9, EOB), a radiochemical purity of ≥98% and compared to the published two‐pot procedure with a notably increased molar activity of 116 ± 18.5 GBq/μmol (n = 7, EOS). The PET images over 60 min showed high uptake of [18F]FESCH in the striatum (Figure 1), which is consistent with the known A2AR distribution pattern in the brain. Although not significant, slightly higher striatal A2AR binding was found in rotenone‐treated mice. Conclusions The radiotracer [18F]FESCH proved to be suitable for in vivo imaging of the adenosine A2A receptor in the mouse brain. Since the increased A2AR availability appears to be related to dyskinesia, it has to be proven whether the investigated mouse model of PD reflects this aspect. ACKNOWLEDGMENTS The European Regional Development Fund (ERDF) and Sächsische Aufbaubank (SAB) are acknowledged for financial support (Project No. 100226753). RE FER EN CES 1. Ramlackhansingh et al., Neurology, 76, 2011 2. Khanapur et al., J. Med. Chem., 57, 2014 3. Shinkre et al., Bioorg. Med. Chem. Lett., 20, 2010 4. Bhattacharjee et al., Nucl. Med. Biol., 38, 2011 5. Khanapur et al., J. Nucl. Med., 58, 2017
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-029 | Ligand effect in the radiofluorination of aryl pinacol boronates catalyzed by copper (II) triflate complexes Dmitrii Antuganov1; Vasilii Timofeev1; Ksenia Timofeeva1; Mikhail Zykov1; Viktoria Orlovskaya2; Raisa Krasikova3 1
Almazov National Medical Research Centre, Russian Federation; 2 N.P.
Bechtereva Institute of Human Brain, Russian Academy of Science, Russian Federation; 3 N.P.Bechtereva Institute of Human Brain Russian Academy of Sciences, Russian Federation
Objectives Cu (OTf)2(Py)4 has recently been introduced as an efficient catalyst in the nucleophilic radiofluorination of aryl pinacol boronates (arylBPin) allowing for the introduction of the fluorine‐18 into various electron‐rich arenes.1 However, for less reactive precursors, for example, benzooxazole‐5‐
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boronic acid pinacol ester, only 8% radiochemical conversion (RCC) can be achieved using this this catalyst.2 Lately, replacing pyridine in Cu (OTf)2(Py)4 with imidazo[1,2‐b] pyridazine (impy) has been shown to increase RCC near 4‐fold when applied to the [18F]olaparib synthesis.3 In a similar approach, we have prepared a series of copper (II) triflate complexes with p‐substituted pyridines, 2,2'‐bipyridine, and 1,10‐phenanthroline (2‐9) to be examined for their catalytic efficiency in radiofluorination of benzooxazole‐5‐boronic acid pinacol ester (I) as a model aromatic substrate. Methods [18F]fluoride was isolated from irradiated [18O]H2O using OASIS WAX 1cc (30 mg) cartridge pre‐conditioned with NaHCO3 solution. Radionuclide was eluted from the cartridge with a solution of 4‐dimethylaminopyridinium triflate (25 μmol) in DMA (0.5 mL) as described elsewhere.4 The eluate was collected into the vial containing 5 μmol of copper complex 1‐9 and 10 μmol of I dissolved in 0.5 mL of DMA. The mixture was heated (110°C, 20 min) in a sealed vial under air. After cooling the RCC was determined using radioTLC. Results To estimate catalytic efficiency of the complexes in question, we have followed a typical protocol reported for the
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radiofluorination of arylBPin precursors, using Cu (OTf)2(Py)4 as the catalyst and 4‐dimethylaminopyridinium triflate as a PTC.4 Under these conditions the RCC for I was 28 ± 4%. Looking at the new potential catalysts, almost no fluorination was observed in the reactions involving compounds 2 and 3. The fluorination efficiency of 4 and 5 (Entry 4 and 5) was slightly higher compared to Cu (OTf)2Py4. However, introduction of 4‐fluoromethyl‐ or 4‐phenylpyridine (Entries 8 and 9) as ligands instead of pyridine has significantly improved observed RCC (up to 75%) compared to the original catalyst (Cu (OTf)2Py4). Conclusions Replacing pyridine in the Cu (OTf)2(Py)4 with other ligand appears to provide an interesting opportunity to fine‐tune the catalytic efficiency of the complex in question when applied to the fluorination of arylBPin precursor I as a model compound. It is likely that this effect extends to other substrates and may be of a particular value for fluorinated arenes which are not easy accessible via use of common catalytic complexes. The feasibility of this approach will be further investigated for possible applications in the synthetic routes to other radiofluorinated arene compounds via copper‐mediated fluorination of arylBPin precursors.
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ACKNOWLEDGEMENTS This research was supported by RFBR grant № 16‐54‐ 12062\18. R EF E RE N C E S 1. M. Tredwell et al., Angew. Chem. Int. Ed., 2014, 53(30), 7751‐7755 2. N. J. Taylor et al., J. Am. Chem. Soc., 2017, 139(24), 8267‐8276 3. T. Wilson et al., J. Nucl. Med., 2018, DOI: https://doi.org/10.2967/ jnumed.118.213223 4. D. Antuganov et al., Eur. J. Org. Chem., DOI https://doi.org/ 10.1002/ejoc.201801514R1
Entry
Catalyst
RCC,%, N = 3 for all 28±4
1
Cu (OTf)2Py4
2
Cu (OTf)2(bpy)2
3±1
3
Cu (OTf)2(phen)2
2±1
4
Cu (OTf)2(C5H4N‐pMe)4
45±2
5
Cu (OTf)2(C5H4N‐pOMe)4
35±4
6
Cu (OTf)2(C5H4N‐pCN)4
29±1
7
Cu (OTf)2(C5H4N‐pNMe2)4
18±1
8
Cu (OTf)2(C5H4N‐pCF3)4
74±6
9
Cu (OTf)2(C5H4N‐pPh)4
73±5
Poster Cate gory: Radiochemistry ‐ 18 F P-030 | Elution efficiency of [18F]fluoride from OASIS WAX cartridge using DMA solution of 4‐dimethylaminopyridinium trifluoromethanesulfonate Dmitrii Antuganov1; Vasilii Timofeev1; Ksenia Timofeeva1; Viktoria Orlovskaya2; Raisa Krasikova3 1
Almazov National Medical Research Centre, Russian Federation; 2 N.P.
Bechtereva Institute of Human Brain, Russian Academy of Science, Russian Federation; 3 N.P. Bechtereva Institute of Human Brain Russian Academy of Sciences, Russian Federation
Objectives The recently suggested copper‐mediated radiofluorination of arly pinacol boronates (ArylBPin)1 greatly facilitates the access to 18F‐fluorinated aromatic amino acids and other complex molecules. Further adjustment of this methodology, in particular, 18F‐recovery step, for routine preparation of the radiotracers, has been the focus of the recent research.2,3 Previous work4 has shown that [18F]F‐ trapped on Oasis WAX cartridge
preconditioned with NaHCO3 can be eluted with a solution of 4‐dimethylaminopyridinium trifluoromethanesulfonate (I) in aprotic solvents such as DMF or DMA (up to 80% elution efficiency—EE). The successful use of this methodology in radiofluorination of ArylBPin precursors4 prompted us to investigate other preconditioning agents to increase the EE. The method efficiency was controlled via model fluorination of 4‐biphenylboronic acid pinacol ester (II) in the presence of Cu (OTf)2Py4. Methods An Oasis WAX 1cc cartridge (30 mg) was rinsed with 5 mL of preconditioning agent and 10 mL of water. Aqueous [18F]fluoride (1.3‐1.8 mL) was loaded onto the cartridge from the male side, rinsed with 1 mL of i‐PrOH in the same direction and dried by compressed air. The waste radioactivity was measured, allowing to evaluate “rinsing loss, %.” [18F]Fluoride was eluted from the female side with 25 μmol of I in 0.5 mL of DMA into the vial containing 5.3 μmol of Cu (OTf)2Py4 and 17.9 μmol of II. The mixture was heated (110°C, 20 min) in a sealed vial under air. After cooling, the radiochemical conversion (RCC) was determined by radioTLC. All the experiments were performed at least in triplicate. Results As it has seen from the table, in most cases, trapping and elution efficiencies of [18F]fluoride were over 90 and 75%, respectively. However, for the acids‐based agents (3‐9), very poor RCC's and high rinsing loss were observed. The use of alkali metal salts for preconditioning was more effective. However the compromise between rinsing loss, EE and RCC values was reached for conditioning of Oasis WAX with NaHCO34 (Entry 10). The EE were slightly higher for compounds 13 and 15‐19, but the fluorination was less effective compared with NaHCO3. Conclusions The solutions of inorganic salts of strong bases and week acids have been found to be the best conditioning agents when combined with weak anion exchange resin Oasis WAX. Our results show that copper‐mediated fluorination of ArylBPin precursors clearly benefits from tailoring [18F]fluoride processing conditions. ACKNOWLEDGEMENTS This research was supported by RFBR grant no 16‐54‐ 12062\18.
RE FER EN CES 1. M. Tredwell et al., Angew. Chem. Int. Ed., 2014, 53(30), 7751‐7755 2. A.V. Mossine et al., Sci. Rep., 2017, 7(1), 233. 3. B.D. Zlatopolskiy et al., Chem. Eur. J., 2017, 23(14), 3251‐3256 4. Antuganov D., et al., Eur. J. Org. Chem., 2018, DOI: https://doi. org/10.1002/ejoc.201801514R1.
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Preconditioning Trapping Rinsing RCC, No agent Efficiency, % Loss, % EE, % % 1
None
93 ± 1
14 ± 1
69 ± 3 64 ± 2
2
Water
88 ± 3
12 ± 3
75 ± 2 58 ± 2
3
1M TfOH
96 ± 3
58 ± 5
72 ± 5 2 ± 1
4
1M TsOH
92 ± 3
71 ± 2
63 ± 4 0
5
1M MsOH
98 ± 1
45 ± 4
76 ± 1 0
6
1M H2SO4
41 ± 3
59 ± 3
77 ± 5 3 ± 2
7
1M H3PO4
97 ± 1
13 ± 2
80 ± 5 7 ± 3
8
1M HCl
98 ± 1
52 ± 8
71 ± 2 3 ± 1
9
1M AcOH
97 ± 1
2±1
87 ± 2 10 ± 1
10
0.5 M NaHCO3
98 ± 1
1±1
78 ± 2 96 ± 3
11
0.5M K2CO3
57 ± 9
37 ± 1
78 ± 2 91 ± 3
12
0.5M NaOAc
98 ± 1
0.2 ± 0.1 72 ± 5 85 ± 2
13
0.5M KOTf
97 ± 1
2±1
14
0.5M PPTS
92 ± 2
57 ± 3
15
0.5M K2HPO4
84 ± 2
8±3
80 ± 5 80 ± 1
16
0.5M KCl
96 ± 1
1±1
80 ± 5 85 ± 1
17
0.5M NaH2PO4
96 ± 3
6±1
88 ± 1 23 ± 5
18
0.5M Na2SO4
87 ± 1
15 ± 2
80 ± 1 92 ± 1
19
0.5M Et4NHCO3
95 ± 3
1±1
82 ± 2 84 ± 3
20
0.5M NH4OH
91 ± 1
8±3
78 ± 4 86 ± 2
21
0.5M NaOH
90 ± 2
9±1
75 ± 2 83 ± 4
82 ± 1 83 ± 2 67 ± 1 0
Poster Cate gory: Radiochemistry ‐ 18 F P-031 | Synthesis of 18F‐labelled fragmented antibody [18F]Fab Olli Eskola1; Cheng‐Bin Yim2; Tim Johnson3; Jorgen Bergman4; Olof Solin5 1
Turku PET Centre, University of Turku, Finland; 2 Turku PET Centre,
Finland; 3 UCB Pharma, United Kingdom; 4 Turku PET Center, Finland; 5
University of Turku, Finland
Objectives Antibodies provide a versatile tool for nuclear medicine, allowing a non‐invasive delivery of radionuclides for diagnostic or therapeutic purposes to cancer cells based on specific molecular recognition.1 As compared to intact antibodies, an engineered antibody fragment (Fab) may offer faster delivery to the target site with retained tumor specificity and rapid clearance from the non‐tumor tissues.2,3 In this study, we present the 18F‐labelling strategy of a 50 kDa monovalent Fab fragment, derived from a humanized IgG, using strain‐promoted alkyne azide cycloaddition reaction (click‐reaction).4
Methods The [18F]Fab precursor 4 (see Fig 1) was synthesized by UCB Pharma through the derivatization of the Fab with dibenzocyclo‐octyne‐PEG4‐N‐hydroxysuccinimidyl ester 1, which reacts with the primary amino residues of the protein backbone. In average, 3.5 linkers were attached per Fab molecule. 18F‐fluoride was produced with 18O(p,n)18F nuclear reaction. After the removal of target water, the radiosynthesis of the [18F]‐PEG4‐azide prosthetic group 3 was achieved by reacting the dried K+/K222/[18F]F‐ complex with the tosyl‐PEG4‐azide precursor 2 (~1.7 mg in 0.5 mL DMSO) at 100°C for 6 minutes. The mixture was diluted with 1.5 mL water and [18F]‐PEG4‐azide 3 was isolated with semi‐ preparative HPLC (Phenomenex Jupiter Proteo 90Å, 10 × 250 mm; 90/10 → 0/100 % H2O/MeOH, 20 min linear gradient, 5.0 mL/min). The fraction of [18F]‐PEG4‐azide 3 (Rt ~13‐14 min) was collected in 20 mL water, and then passed through a Waters HLB 1cc extraction cartridge, which was subsequently washed with 20 mL water. [18F]‐ PEG4‐azide 3 was eluted from the cartridge with 250 μL ethanol. The eluate was mixed with a solution of the Fab‐DBCO precursor 4 (0.56‐1.22 mg). PBS (phosphate buffered saline) was added in such a way that the share of ethanol (v/v) was 1/3 at maximum. This click‐reaction solution was mixed (600 rpm) at 45°C for 25‐30 min. [18F]Fab 5 was isolated from lower‐molecular‐weight side products using size exclusion chromatography (SEC) and an Illustra NAP‐5 cartridge, the procedure of which offered [18F]Fab 5 dissolved in 0.8 ml PBS. Radiochemical purity was analyzed with radio‐HPLC (Column: Waters Xbridge Protein BEH SEC, 125Å, 3.5 μm, 7.8 × 150 mm. Eluent: H2O (0.1 % TFA) /CH3CN 80/20, 0.6 ml/min). Figure 1. 18F‐labelling of DBCO‐modified fragmented antibody 4 utilizing click‐chemistry. Results The radiochemical yield of [18F]‐PEG4‐azide 3 (decay corrected to the end of bombardment and calculated from the initial 18F‐radioactivity) was 19.2 ± 8.1 % and 6.0 ± 1.9 for the isolated [18F]Fab 5, respectively (n = 5). Radiochemical purity of [18F]Fab exceeded 99.0% and was found to remain unchanged up to 3 hours post‐synthesis. The overall synthesis time was ~110 min. Conclusions Radiosynthesis of [18F]Fab using click‐strategy was achieved with high radiopharmaceutical quality and activity yields high enough to enable preclinical experiments. RE FER EN CES 1. Carter LM et al., J Label Compd Radiopharm. 2018;61:611‐635, 2. Viola‐Villegas NT et al., Mol Pharmaceutics 2014;11:3965‐3973, 3. Goldenberg DM et al., J Nucl Med Technol 1997;25:18‐23 4. Agard NJ et al., J Am Chem Soc 2004;126:15046‐15047.
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Poster Cate gory: Radiochemistry ‐ 18 F P-032 | Site‐specific conjugation and fluorine‐18 radiolabeling of non‐immunoglobulin‐based scaffold proteins Mathilde Vandamme1; Frederik Cleeren2; Guy Bormans1 1
KU Leuven, Belgium; 2 Radiopharmaceutical Research, Department of
Pharmacy and Pharmacology, University of Leuven, Belgium
Objectives Due to their high affinity and specificity, non‐immunoglobulin‐based scaffold proteins are increasingly being used as vector molecules for PET radiopharmaceuticals. Fluorine‐18 is among the radionuclides having the most suitable characteristics for in vivo PET imaging. Indeed, it has a high positron abundance (97%), low positron emission energy (634 keV), and can be reliably produced
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in high quantity with a cyclotron (>370 GBq). Moreover, the half‐life of fluorine‐18 perfectly matches the fast pharmacokinetics of non‐immunoglobulin‐based scaffold proteins, providing high contrast images within one to three hours after injection. Furthermore, introduction of an unpaired cysteine residue at the C‐terminus of the protein allows site‐specific conjugation of chelators or radiolabeled groups via maleimide‐thiol reactions, avoiding heterogeneous tracer populations. The aim of the project is to site‐specifically radiolabel a non‐immunoglobulin‐based scaffold protein with the prosthetic group N‐(2‐(2,5‐dioxo‐2,5‐dihydro‐1H‐pyrrol‐1‐yl)‐ethyl)‐ 6‐fluoronicotinamide ([18F]FNEM). In this study, the maleimide‐thiol reaction was optimized using maleimide‐Cy5, and the scaffold protein was characterized before and after conjugation with UPLC‐HRMS. Precursors for direct and indirect radiolabeling of [18F] FNEM1 are synthesized, and the stability of precursor was assessed in radiolabeling conditions.
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Methods From 6‐chloronicotinic acid, the maleimide precursor (5‐((2‐ (2,5‐dioxo‐2,5‐dihydro‐1H‐pyrrol‐1‐yl)ethyl)carbamoyl)‐N, N,N‐trimethylpyridin‐2‐ammonium triflate) was synthesized in six steps; the reference compound FNEM has been synthesized in three steps. The stability of the maleimide moiety under direct radiolabeling conditions (40 °C, K2C2O4, K222, pH 8.45) was assessed using maleimide‐BOC as test compound. Maleimide‐thiol coupling conditions have been optimized using the commercially available fluorescent Cy5‐maleimide. The scaffold protein construct has been characterized using size exclusion chromatography (Superdex 75 10/300 GL) and UPLC System (Zorbax SB‐C3 column, 3 mm × 100 mm, 1.8 μm) coupled in series to an ultra‐high resolution time of flight mass spectrometer (ESI‐ TOF‐HRMS, MaXis impact, Bruker) before and after derivatization with maleimide‐Cy5 and FNEM. Results Both the maleimide precursor and FNEM were successfully synthesized. Stability studies showed that the maleimide‐ precursor is able to withstand direct radiolabeling conditions with minor degradation; still 71% of precursor was intact under these conditions. The optimal maleimide‐thiol coupling conditions were found to be 15 min at room temperature in a 20 mM HEPES/150 mM NaCl buffer containing 0.1 mM TCEP (tris(2‐carboxyethyl)phosphine) at pH 7.2. The TCEP concentration was found to be crucial as higher concentration resulted in low conjugation yields and lower concentration resulted in the formation of dimers of the protein. High resolution mass analysis showed a molecular ion mass corresponding to the calculated mass of the Cy5‐ maleimide‐protein construct, and the Cy5‐derivatized protein eluted as a single peak using SEC with UV detection 647 nm. Using optimized conditions, we have been able to achieve the coupling reaction with FNEM. We observed a neutral average mass corresponding to the calculated mass of the fluoronicotinic‐maleimide derivatized protein. Direct radiolabeling of [18F]FNEM and radiolabeling of the protein is under progress. Conclusions We successfully characterized the scaffold protein before and after conjugation with Cy5‐maleimide and FNEM. The optimal maleimide‐thiol conjugation conditions were 20 mM HEPES, 150 mM NaCl, and 0.1 mM TCEP, pH 7.2 at room temperature. Precursors for direct and indirect radiolabeling of [18F]FNEM are synthesized and stability studies showed that the maleimide‐precursor is able to withstand direct radiolabeling conditions.
R EF E RE N C E S 1. Yue, X.; Yan, X.; Wu, C.; Niu, G.; Ma, Y.; Jacobson, O.; Shen, B.; Kiesewetter, D. O.; Chen, X. Mol. Pharmaceutics 2014, 11, 3875‐3884.
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P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-033 | Development of new fluorination methods for fluorine‐18 labelling of aromatic compounds Rémi Pelletier; Bertrand Kuhnast; Simon Specklin Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS, Université Paris Sud, Université Paris‐Saclay, Service Hospitalier Frédéric Joliot, France
Objectives Considering the low reactivity of [18F]fluoride anion, radiolabelling of non‐activated aromatic compounds remains a modern challenge and can affect the development of radiotracers. Despite the handful of recent methods available, such as the copper‐mediated fluorination of boronic esters1 or the deoxyfluorination of phenols2, the development of 18F‐probes based on an electron‐rich aromatic fluorination is still substantially limited. In this work, new radiofluorination strategies based on concerted nucleophilic aromatic substitution (cSNAr)3 are explored. In that way, model aromatic rings were substituted with specific leaving groups (LG) carrying a directing group (DG) to guide fluorides during the aromatic fluorination. To evaluate the potential of the developed methods, the radiolabelling of the anticancer drug Binimetinib will be studied. Beyond the challenge of the synthesis of [18F]Binimetinib, the molecule would be an important key for the study of the MAPK/ERK pathway that is involved in the cell death and proliferation mechanism. In order to compare our method with the actual gold standards while securing the access to [18F]Binimetinib, the labelling will be performed first via a method already described. Methods Alkyl ammoniums are often used as efficient LG in SNAr and are studied in this work in conjunction with a boron based directing group, relying on the boron affinity for fluoride4. Several borylated aromatic ammoniums precursors were synthesized along with the corresponding trimethylammoniums derivatives used as references for the aromatic fluorination. The reaction course of those compounds with several fluoride sources have been monitored by LC‐MS. Before using these methods for the labelling of [18F]Binimetinib, the radiosynthesis of this compound is studied by copper mediated fluorination of the corresponding boronic ester derivative. This precursor was synthetized from a commercial advanced precursor. In that way, [18F]Binimetinib will be prepared via a copper catalysed substitution of the boronic ester to secure
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the access to the radiotracer before evaluating the new methodology. Results Two couples of borylated ammoniums and the corresponding trimethylammoniums were obtained in a 4 to 5 steps synthesis with 50% to 95% overall yields. Fluorination of these compounds from an excess of four different fluoride salts has shown a moderate conversion in aryl fluoride of around 10% with similar result between the trimethyl‐ and borylated ammoniums. The boronic ester used as a radiolabelling precursor for the synthesis of [18F]Binimetinib has been obtained in 6 steps from an advanced precursor with a 15% overall yield. Its labelling by copper mediated radiofluorination is currently under investigation. Conclusion The first set of compounds based on the association of a directing group with a leaving group led to minor influences in the SNAr with fluoride. These first observations resulted in the design of several other precursors whose synthesis is currently studied. The synthesis of the boronic ester precursor of the [18F]Binimetinib was developed and the preliminary evaluation of the labelling of this compound is currently studied. ACKNOWLEDGMENTS Supported by CEA intramural “Phares” PhD program. R EF E RE N C E S 1. Tredwell, M.; Preshlock, S. M.; Taylor, N. J.; Gruber, S.; Huiban, M.; Passchier, J.; Mercier, J.; Génicot, C.; Gouverneur, V. A General Copper‐Mediated Nucleophilic 18 F Fluorination of Arenes. Angewandte Chemie International Edition 2014, 53 (30), 7751–7755 2. Campbell, M. G.; Ritter, T. Late‐Stage Fluorination: From Fundamentals to Application. Organic Process Research & Development 2014, 18 (4), 474–480. 3. Neumann, C. N.; Hooker, J. M.; Ritter, T. Concerted Nucleophilic Aromatic Substitution with 19F− and 18F−. Nature 2016, 534 (7607), 369–373. 4. Wade, C. R.; Broomsgrove, A. E. J.; Aldridge, S.; Gabbaï, F. P. Fluoride Ion Complexation and Sensing Using Organoboron Compounds. Chemical Reviews 2010, 110 (7), 3958–3984.
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P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-034 | Improved and simpler radiosynthesis of [18F]ADAM, a radioligand for PET imaging of serotonin transporters Selena Milicevic Sephton; Xiaoyun Zhou; Stephen Thompson; Franklin Aigbirhio University of Cambridge, United Kingdom
Objectives Serotonin transporter (SERT) plays an important role in termination of action of serotonin and recycling it to the presynaptic neuron. Altered SERT has been found in brain disorders such as mood disorders, Alzheimer's disease, and Parkinson's disease. Positron‐emission tomography (PET) with suitable radioligands for SERT could serve to study the function of SERT in various brain diseases. [18F]ADAM, an F‐18 analogue of the most used SERT tracer [11C]DASB, was developed and evaluated in rodents and non‐human primates.1 The radiotracer displayed favourable pharmacokinetics and binding profile to SERT. However, the use of [18F]ADAM ([18F]2, Figure 1) is limited due to its radiolabelling procedure being laborious and provides [18F]ADAM in low radiochemical yield (ca. 1‐15%).2–4 Here, we report a new improved method for the radiosynthesis of [18F] ADAM, aiming to simplify radiolabelling and improve RCY. Methods We adopted the copper‐mediated 18F‐fluorination method described by Preshlock et al5 with appropriate
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modifications. First, precursor 1 bearing an aryl boronic ester was reacted with [18F]KF/K222 in dimethylformamide or dimethylacetamide in the presence of Cu (OTf)2(py)4. After the radiolabelling step, 4M HCl was added to remove the tert‐butyloxycarbonyl protecting group followed by neutralization with 4M NaOH. Various solvents, reaction temperature, reaction time, precursor/catalyst ratio, and precursor concentration were tested to optimize the reaction. Results [18F]ADAM was successfully synthesized with an RCY of 30 ± 10% (n = 6). Comparing various radiolabelling conditions, the highest RCY was obtained by reaction of 0.01 mmol precursor 1 with 20‐50 MBq [18F]KF/K222 in 300 μl dimethylacetamide in the presence of Cu (OTf)2(py)4. The fluorination yielded 32 ± 10% conversion to the protected intermediate at 90°C for 10 min. The subsequent deprotection step took 10 min with >90% yield. Conclusions We have developed a new, simpler, and improved radiolabelling method for [18F]ADAM, with high RCY (30% vs 15% published) and reduced time of synthesis (1h vs 2h published). The radiolabelling procedure is straightforward and can be easily scaled up and implemented in various synthetic modules. ACKNOWLEDGEMENTS The authors would like to acknowledge Dr. Bianca Jupp (University of Cambridge, UK) for many useful discussions. R EF E RE N C E S 1. U. Ackermann, et al J. Label. Compd. Radiopharm. 2004, 47, 523–530. 2. Y. Y. Huang, et al Appl. Radiat. Isot. 2012, 70, 2298–2307. 3. Y. Y. Huang, et al Appl. Radiat. Isot. 2009, 67, 1063–1067. 4. C. J. Peng, et al Appl. Radiat. Isot. 2008, 66, 625–631. 5. S. Preshlock, et al Chem. Commun. 2016, 52, 8361–8364.
Poster Cate gory: Radiochemistry ‐ 18 F P-035 | New strategy for infection PET imaging by fluorine‐18 labeling of a bacterial azide‐containing LPS Simon Specklin1; Aurelie Baron2; Marie‐Ange Badet‐Denisot2; Boris Vauzeilles2; Bertrand Kuhnast1 1
Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS,
Université Paris Sud, Université Paris‐Saclay, Service Hospitalier Frédéric Joliot, France; 2 ICSN, UPR‐CNRS 2301, 91198, Gif‐sur‐Yvette Cedex, Université Paris‐Saclay, France
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Objectives Early diagnosis of bacterial infection is a key challenge for a fast and efficient treatment of infected patients. Among all the imaging techniques, opportunities offered by nuclear medicine are in contrast with the limited number of available radiopharmaceuticals.1 In PET imaging, 18F‐FDG remains the gold standard but suffers from a lack of specificity, reinforcing the need of the development of probes with improved specific targeting. This work focuses on the establishment of a new strategy for PET imaging of infection by combining biorthogonal chemistry and the metabolic incorporation of an azide‐modified monosaccharide in the bacteria lipopolysaccharide (LPS).2 In that way, a fluorine‐18 cyclooctyne was developed and used for the SPAAC click reaction with the azide‐containing bacteria, paving the way for a new strategy for bacteria labeling. Methods The synthesis of a sugar substituted with an azide function (KDO‐N3) was developed starting from D‐arabinose. Bacteria were then fed with KDO‐N3 in various culture conditions to optimize its incorporation in the LPS. Azide‐containing bacteria were analyzed by fluorescent labeling in flow cytometry. Synthesis and radiosynthesis of a cyclooctyne based on the DBCO scaffold and labeled with fluorine‐18 were developed. In vitro labeling of the azide‐bacteria was studied by incubation with 18F‐DBCO under several conditions. Control experiments with standard bacteria were performed for each conditions. After incubation, the labeled bacteria were washed and recovered by centrifugation to determine the activity incorporated. Results KDO‐N3 was obtained after an 11 steps synthesis with 17% overall yield. Non‐pathogenic Escherichia coli MG1655 bacteria were used and cultivated with KDO‐N3 (4 mM) for 9 h at 37°C then 15 h at 4°C. Control bacteria were cultivated in the same conditions without KDO‐N3. Radiolabeling tosyloxy‐precursor and non‐radioactive reference were respectively synthesized in 4 and 5 steps with 36% and 18% overall yield. A fully automated radiosynthesis was developed, including radiofluorination with K[18F]F/K222 at 90°C in acetonitrile for 15 min and resulting in the production of 18F‐DBCO with a typical decay‐corrected yield of 17% and 6.8 GBq (EOB) over a 80 min synthesis time. In vitro labeling of the azide‐containing bacteria was performed after incubation with 18F‐DBCO for 1 h and led to 5.8 MBq (EOB) labeled bacteria. Conclusion 18 F‐DBCO cyclooctyne was developed and used for the radioactive labeling of bacteria displaying an azide‐ modified sugar. In vitro labeling of these bacteria was achieved, and in vivo application of this strategy is currently studied to propose a new imaging tool of the bacterial infection.
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ACKNOWLEDGMENTS This work is supported by an “amorces de collaboration” program of WP1‐France Life Imaging. R EF E RE N C E S 1. Dutta, J.; Naicker, T.; Ebenhan, T.; Kruger, H. G.; Arvidsson, P. I.; Govender, T. Eur. J. Med. Chem. 2017, 133, 287–308. 2. Dumont, A.; Malleron, A.; Awwad, M.; Dukan, S.; Vauzeilles, B. Angew. Chem. Int. Ed. 2012, 51, 3143–3146.
Poster Cate gory: Radiochemistry ‐ 18 F P-036 | Novel Pyridinyl Quarternary Ammonium Salts as Precursors of Radiofluorination David Blevins1; Murthy Akula2; George Kabalka2; Dustin Osborne2 1
The University of Tennessee, GSM, United States; 2 University of
Tennessee Medcial Center, United States
Objective Several important PET radiotracers have pyridine ring structure, and in many cases the alpha position to nitrogen has [F‐18]fluorine.1,2 Generally, the [F‐18]fluoride is introduced by fluorodehalogenation, fluorodenitration, or by displacing a labile quartenary ammonium as a good leaving group. Currently, trimethylammonium triflates are used as
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efficient precursors for radiofluorination. We wish to report the fluorination of new pyridinyl quarternary ammonium salts derived from DABCO, quinuclidine, and DMAP as precursors for radifluorination. Methods The requisite quarternary ammonium salts 2 were prepared in quantitative yields by reacting halopyridines 1 with DABCO, quinuclidine, or DMAP in THF at ambient temperature for 16 h. The resulting salts were filtered and thoroughly dried under vacuum. The radiofluorination was carried out by reacting these salts with [18F]F‐K+/ K222 using Sofie Elixys Radiochemistry flatform. Results Several 3‐substituted 6‐pyridinyl ammonium salts were radiofluorinated (Table). Cyclotron produced fluoride dried using automated sequence on the Sofie system, and the Precursor 2 (10 mg) in DMSO (1.0 mL) was transferred to reaction vial containing anhydrous fluoride. The resulting mixture was heat at 50°C for 20 min. The product was purified through a C18 Sep‐Pak cartridge, and the radiochemical yields were determined using Bioscan radio‐TLC(10% EtOAc in Hexanes). Conclusions Various pyridinyl quarternary ammonium salts were successfully transformed into corresponding [18F] fluoropyridines at low temperature (50°C) with high radiochemical yields. (40‐80%). These salts start decomposing at 60°C. ACKNOWLEDGEMENTS We wish to acknowledge the Molecular Imaging and Translational Research Program and University Health Systems, Knoxville for the support of this research. RE FER EN CES 1. Alam, M et al. J. Label Compd Radiopharma 2017, 60, S376. 2. Lindmenn, M et al. J Label Compd Radiopharma 2017, 60, S247.
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SUPPLEMENT ARTICLES
Number
R1
R
% Yield of 3
1
DABCO
CHO
72
2
DABCO
COOEt
85
3
DABCO
COCH3
83
4
DABCO
CN
74
5
quinuclidine
CHO
85
6
quinuclidine
COOEt
81
7
quinuclidine
COCH3
83
8
quinuclidine
CN
77
9
DMAP
CHO
66
10
DMAP
COOEt
75
11
DMAP
COCH3
40
12
DMAP
CN
80
Poster Cate gory: Radiochemistry ‐ 18 F P-037 | Synthesis and in‐vitro evaluation of novel PET probes 18F‐CNPI and 18F‐CNBI for glycogen synthase kinase‐3 imaging Mukesh Pandey1; Heather Berg2; Nicholas Nelson2; Aditya Bansal2; Abigail Walsh2; Lee Peyton2; Timothy DeGrado3; Val Lowe2; Mark Frye2; John Port2 1
Department of Radiology, Mayo Clinic, United States; 2 Mayo Clinic
Rochester, United States; 3 Mayo Clinic, United States
Objective The objectives of the present work were to synthesize and radiolabel highly selective and blood brain permeable positron emission tomography (PET) probes for glycogen synthase kinase‐3 (GSK‐3). GSK‐3 has been implicated in various cancers, neurodegenerative, and psychiatric diseases.1 A successful development of PET probe for GSK‐ 3 imaging will help in better understanding of GSK‐3's role in pathophysiology of different diseases and thus help to advance the development of new therapeutics. Methods Taking a lead from a previous study,2 two novel 18F‐ labeled PET probes, 2‐(cyclopropanecarboxamido)‐N‐(4‐ [18F‐ (4‐18F‐fluorophenyl)pyridin‐3‐yl)isonicotinamide CNPI] and 2‐(cyclopropanecarboxamido)‐N‐(6‐(fluoro‐ 18 F)‐[3,4'‐bipyridin]‐3'‐yl)isonicotinamide [18F‐CNBI], were synthesized using their respective nitro precursors, 2‐(cyclopropanecarboxamido)‐N‐(4‐(4‐nitrophenyl)pyridin‐3‐yl)isonicotinamide and 2‐(cyclopropanecarboxamido)‐N‐(6‐(nitro)‐[3,4'‐bipyridin]‐3'‐yl)isonicotinamide. A standard, nucleophilic reaction using cryptand (Kryptofix/K222, 8.1 mg), potassium carbonate (K2CO3,
4.0 mg), and 18F‐fluoride was employed for the 18F‐labeling. The labeling was performed at 165°C, 30 min in anhydrous DMSO using 5 mg of nitro precursor and 4 mg of 18‐ crown‐6 as a catalyst. Final products were purified using an Oasis HLB Sep‐Pak and concentrated through a standard C‐18 plus solid phase extraction cartridge via trap and release. The identities of the synthesized PET probes 18F‐ CNPI and 18F‐CNBI were confirmed using their respective non‐radiative reference standards 19F‐CNPI and 19F‐CNBI on an analytical HPLC. All the radiosyntheses were carried out manually. Reference compounds 19F‐CNPI and 19F‐ CNBI were evaluated through parallel artificial membrane permeability assay (PMPA) at pH 7.4 for blood brain barrier permeability, and their selective binding (IC50 value) for both GSK‐3α and GSK‐3β was measured using GSK‐3α/β kinase enzyme system (Promega Corporation), whereas kinase activity was detected by “ADP‐GloTM” assay (Promega Corporation). Results Radiosyntheses of 18F‐CNPI and 18F‐CNBI were achieved successfully in a 5‐11% uncorrected yields at end of synthesis and purification. Overall, synthesis and purification was performed in ~55‐60 min. Based on r‐TLC, the unpurified labeling yields were 21% and 41% for 18F‐CNPI and 18F‐CNBI, respectively. Non‐radioactive reference standards and precursors were synthesized in multi‐steps and fully characterized by 1H‐NMR, 19F‐NMR, 13C‐NMR, and HRMS. GSK‐3α/β kinase enzyme system showed IC50 value of 6.7 ± 0.6 nM and 7.5 ± 0.3 nM for 19F‐CNPI and 29.1 ± 1.6 nM and 29.7 ± 5.8 nM for 19F‐CNBI, against GSK‐3α and GSK‐3β, respectively. The PMPA assay showed Avg. Pe 38 × 10−6 and 1.6 × 10−6cm/s for 19 F‐CNPI and 19F‐CNBI, respectively. Conclusions Two novel PET probes 18F‐CNPI and 18F‐CNBI were developed for imaging GSK‐3. The PMPA assay showed both the probes are blood brain barrier permeable and have high affinity for GSK‐3α and GSK‐3β. A fully automated radiosynthesis and in‐vivo evaluation of the developed PET probes in specific mouse model will be performed as future study. ACKNOWLEDGEMENT This study was funded by Department of Radiology, Mayo Clinic Rochester as part of small grants program to MKP. RE FER EN CES 1. M K. Pandey, T. R. DeGrado. Glycogen Synthase Kinase ‐3 (GSK‐3) Targeted Therapy and Imaging. Theranostics, 2016, 6(4), 571‐593. 2. G. Luo, L. Chen, C. R. Burton, H. Xiao, P. Sivaprakasam et al. Discovery of Isonicotinamides as Highly Selective, Brain Penetrable, and Orally Active Glycogen Synthase Kinase‐3 Inhibitors. J Med Chem. 2016; 59(3): 1041‐1051.
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Poster Cate gory: Radiochemistry ‐ 18 F P-038 | Radiofluorination of higher‐valent aryliodines: A comparative investigation of [18F]fluoroarenes produced from hypervalent compounds a different oxidation states Young‐Do Kwon; Jeongmin Son; Young Hoon Ryu1; Joong‐Hyun Chun2 1
Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei
University College of Medicine, Republic of Korea; 2 Yonsei University College of Medicine, Republic of Korea
Objectives Unlike other classes of hypervalent compounds used to produce [18F]fluoroarenes 1, the reactions of [18F]fluoride ions with hypervalent iodine precursors such as diaryliodonium salts and aryliodonium ylides are now well‐established for introducing fluorine‐18 (t1/2 = 109.7 min) onto aryl rings to generate new radiotracers for positron emission tomography (PET) imaging studies.2 Recently, the direct use of higher‐valent, oxidized iodoarenes (OIAs) was demonstrated to be useful
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for producing various [18F]fluoroarenes.3 However, it is still not clear which hypervalent species in the oxidized mixture is the main active precursor for radiofluorination. Therefore, we investigated the labelling efficacy of different λ3‐ and λ5‐oxidized hypervalent aryliodines as precursors for no‐carrier‐added aromatic radiofluorination. Methods Azeotropically dried 18F‐‐K2.2.2‐K+ or TBA18F complex (74−110 MBq/500 μL) and each hypervalent precursor (2–3 mg) in solvent (DMSO or DMA; 1.5 mL) were mixed manually and radiofluorinated at 160°C for 10 min. The temperature and reaction time were fixed to compare the radiochemical yields (RCYs) of [18F]fluoroarenes. The reaction mixture was quenched directly with MeCN‐H2O (40: 60 v/v, 3 mL) and subject to radio‐high‐ performance liquid chromatography (HPLC). RCYs were determined based on the reverse‐phase radio‐HPLC chromatogram. Results [18F]Fluoroarenes were prepared from hypervalent precursors with different oxidation states of iodine (Figure 1). For example, with iodotoluene derivatives, λ5‐iodoxyarene gave the highest RCY (~62%). Unlike a previous report, [18F]fluorotoluene was not acquired from (diacetoxyiodo)toluene.4 [18F]Fluorotoluene 3 was obtained from the λ ‐hypervalent iodosyl and benziodoxole derivatives in 32 and 13% RCY, respectively. Aryl‐iodyl derivatives, which are polymers in the solid state (ArI=O), provided moderate RCYs (15~32%). Interestingly, cyclic λ3‐benziodoxole derivatives also produced electron‐rich [18F]fluoroarenes, albeit in low RCYs (3~13%). Other λ3‐hypervalent derivatives failed to provide the corresponding [18F]aryl fluorides. Conclusions Radiofluorination of λ3‐ or λ5‐hypervalent aryliodines provided various [18F]fluoroarenes. In general, λ5‐ iodoxyarenes gave higher RCYs than λ3‐hypervalent precursors. Oxidized, higher‐valent iodoarenes may find
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useful applications in the production of other radiotracers, particularly with aromatic radiofluorination. ACKNOWLEDGEMENTS This work was supported by the National Research Foundation (NRF) of Korea, funded by the Ministry of Science (NRF‐2015R1D1A1A02061420). R EF E RE N C E S 1. Tredwell, M.; Gouverneur, V. Angew. Chem. Int. Ed. 2012, 51, 11426. 2. Pike, V. W. J. Labelled Compd. Radiopharm. 2018, 61, 196. 3. unpublished results 4. Haskali, M. B.; Telu, S. et al., J. Org. Chem. 2016, 81, 297.
Poster Cate gory: Radiochemistry ‐ 18 F P-039 | One‐step synthesis of [18F]fluoro‐4‐ (vinylsulfonyl)benzene (FVSB): A thiol reactive synthon for selective radiofluorination of peptides and proteins Jennifer Murphy; Gaoyuan Ma University of California Los Angeles, United States
Objectives Radiolabeled peptides and proteins are important diagnostic tools due to their selectivity towards overexpressed cell surface receptors of many cancers, which can be exploited for targeting purposes.1,2 Selective bioconjugation reactions for 18F‐labeling of peptides and proteins have largely focused on the modification of cysteine residues. Currently, the gold‐standard for 18F‐labeling via thiol‐reactive bioconjugations are maleimide‐based synthons; however, these conjugates exhibit low stability and are susceptible
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to a Retro‐Michael addition reaction.3 We report an 18F‐ labeled vinyl sulfone, [18F]fluoro‐4‐(vinylsulfonyl)benzene ([18F]FVSB), as a thiol‐reactive synthon for site‐specific radiolabeling of peptides and proteins, for applications in positron emission tomography (PET) molecular imaging. Methods One‐step synthesis of [18F]FVSB was achieved following the deoxyfluorination of phenols methodology reported in literature.4 In five steps, starting from thiophenol, the vinyl sulfonyl precursor was obtained as a crystaline solid. No azeotropic drying of [18F]fluoride is needed. The precursor was utilized to elute [18F]fluoride from an ion exchange cartridge, and the reaction was heated to 130°C for 20 mins. [18F]FVSB was used without HPLC purification for subsequent bioconjugation. Radiochemical conversions (RCC) were determined by radio‐Thin Layer Chromatography (radio‐TLC) and the identity of [18F] FVSB was confirmed by radio‐HPLC via co‐injection with the fluorine‐19 reference standard. Results [18F]FVSB was synthesized in 77‐96% RCC and purified via a C18 SPE cartridge. [18F]FVSB displays rapid and selective reactivity with thiol‐containing peptides and was utilized for the site‐specific 18F‐labeling of a model RGDC peptide. Incubation with an RGDC peptide in methanol/buffer at 35 oC provided the 18F‐labeled peptide conjugate in 20‐27 min with >96% conversion, determined by HPLC. Benefits of [18F]FVSB over other thiol‐reactive synthons include one‐step radiofluorination, high RCC, no HPLC purification, improved stability in aqueous environments, rapid bioconjugation, no azeotropic drying of [18F]fluoride, and fully automated synthesis. Conclusions We anticipate the numerous advantages of [18F]FVSB over other thiol‐reactive synthons will facilitate
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extensive utility of this approach for preparation and evaluation of 18F‐labeled peptides and proteins for PET probes.
R EF E RE N C E S 1. Fani, M.; Maecke, H. R.; Okarvi, S. M. Theranostics 2012, 2, 481‐501. 2. Sun, X.; Li, Y.; Liu, T.; Li, Z.; Zhang, X.; Chen, X. Adv. Drug Deliv. Rev.2017,110‐111, 38‐51. 3. Koniev, O.; Wagner, A. Chem. Soc. Rev. 2015,44, 5495‐5551. 4. Neumann, C.N.; Hooker, J.M.; Ritter, J. Nature 2016, 534, 369‐373.
Poster Cate gory: Radiochemistry ‐ 18 F P-040 | Radiofluorination of p‐aminobenzoic acid for bacterial infection imaging with PET Jianyang Fang1; Xiaru Lin; Hongzhang Yang; Jindian Li; Rongqiang Zhuang2; Xianzhong Zhang3 1
State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics
& Center for Molecular Imaging and Translational Medicine, China; 2 State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, China; 3 Xiamen University, China
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Para‐aminobenzoic acid (PABA) is an intermediate in the synthesis of folate by bacteria, which could be specifically recognized and incorporated into both gram‐negative and gram‐positive bacteria. In this work, a novel radiofluorination method was developed to obtain the radiolabeled 2‐[18F]F‐p‐aminobenzoic acid (2‐[18F]F‐ PABA) for bacterial infection imaging in vivo. Methods After the radiofluorination of presursor, methyl 2‐(trimethyl ammoniumtriflate) 4‐nitrobenzoate, with further hydrolysis in alkaline solution, the reaction was continued without purification to reduce the 4‐nitro moiety rapidly to produce 2‐[18F]F‐PABA. The final product was purified and analyzed by radio‐HPLC. Thereafter the in vitro stability of 2‐[18F]F‐PABA was tested in saline and serum, respectively. Results This one‐pot‐synthesis of radiofluorination relied on a conventional nucleophilic aromatic substitution (SNAr) reaction. The overall decay corrected radiochemical yield of 2‐[18F]F‐PABA was 41.21 ± 4.52%. It had good radiochemical purity (>99% after HPLC purification) and high molar activity (65.92 ± 17.60 GBq/μmol, n = 3). 2‐[18F]F‐PABA remains stable in saline or serum after 2 h incubation. Conclusions We have developed a novel, efficient approach to synthesize 2‐[18F]F‐p‐aminobenzoic acid. The further evaluations of this probe in vitro and in vivo are in progress. After completion of the radiochemical study, a related Objectives
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work was reported by Zhang et al (ACS Infect. Dis., 2018,4, 11, 1635‐1644). ACKNOWLEDGMENTS This study was financially supported by the National Key Basic Research Program of China (2014CB744503).
Poster Cate gory: Radiochemistry ‐ 18 F P-041 | Aromatic [18F]fluorination of [18F] BS224 and its bioevaluation in animal models of neuroinflammation and stroke Sang Hee Lee1; In Ho Song2; So Young Lee1; Byung Seok Moon3; Hyun Soo Park2; Sang Eun Kim3; Byung Chul Lee 1
Department of Transdisciplinary Studies, Graduate School of
Convergence Science and Technology, Seoul National University, Republic of Korea; 2 Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea; 3 Seoul National University Bundang Hospital, Korea, Republic of, 4Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea
Objectives Abnormal TSPO (the translocator protein 18 kDa) expression in brain is markedly observed in activated microglia, choroid plexus, and reactive astrocytes.1 The selective TSPO‐binding ligand can provide a powerful imaging tool to detect and monitor inflammatory brain disorders because TSPO expression is significantly low in the normal brain.2 Herein, we have designed an aromatic
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fluorine substituted imidazo[1,2‐a]pyridine analogue, [18F]BS224 that is useful for imaging TSPO overexpression by being high in vivo stability compared to the reported [18F]CB251.3 We now report the radio‐synthesis and in vitro and in vivo evaluation of the novel neuroinflammation imaging PET radioligand. Method [18F]BS224 has been synthesized by two different precursors: i) diaryliodonium salts by using condition A; ii) pinacol boronate ester by using condition B.4 Both conditions for aromatic [18F]fluorination were conducted and optimized in several PTC complexes (K222/K2CO3, 18‐Crown‐6/CsHCO3, and nBu4NHCO3), solvents, temperatures and catalysts. The desired product was collected from semi‐preparative HPLC at 34 min (Waters, Xterra Semi‐preparative C18 column, 10 × 250 mm, 10 μm; 50% acetonitrile‐water, 250 nm, flow rate: 5.0 mL min‐1). In vitro TSPO‐binding and CBR‐binding affinities of BS224 were measured by displacement of [3H]PK11195 and [3H]flunitrazepam, respectively, in rat cereberocortical samples. In vivo TSPO PET studies were accomplished in a lipopolysaccharide (LPS) induced inflammatory and middle cerebral artery occlusion (MCAO) rat models. Result A new aromatic fluorine‐substituted imidazo[1,2‐a]pyridine analogue, BS224, showed a subnanomolar affinity (Ki = 0.51 nM). Using the optimized condition A, [18F] BS224 was synthesized with the range of radiochemical yield (RCY) 18‐25% from diaryliodonium salts precursor based on radio‐TLC analysis of the crude product. In case of the pinacol boronate ester precursor in condition B, much higher RCY of [18F]BS224 (63.6%, based on radio‐ TLC analysis) was shown in the presence of copper (II) triflate and pyridine in dimethylformamide. Finally, we optimized the radio‐synthesis of [18F]BS224 by using condition B including HPLC purification. RCY of the final product was 39 ± 6.8 % (n = 3, decay corrected) with high molar‐activity (127 GBq/μmol) and radiochemical purity (>99 %). The partition coefficient (Log D) and in vitro human serum stability were 2.78 ± 0.04 and over 99% after 2 h, respectively. In animal PET imaging studies, [18F]BS224 provided a clearly visible image of the inflammatory lesion with high signal‐to‐noise ratio in both animal models without no skull uptake as shown Figure. In addition, the displacement studies by injecting of flumazenil and PBR28 indicate that the uptake of the major fraction of [18F]BS224 in the inflammatory lesion was selectively and specifically mediated by TSPO. Conclusion Aromatic [18F]fluorination of [18F]BS224 was successfully performed by nucleophilic substitution of the corresponding the pinacol boronate ester precursor using [18F]fluoride. The results, together with those obtained on
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in vitro TSPO binding, stability, in vivo PET imaging studies with specific and selective binding for TSPO, and a clear visibility of inflammatory lesion in animal models support the conclusion that [18F]BS224 is a promising TSPO PET imaging agent for neuroinflammation.
Poster Cate gory: Radiochemistry ‐ 18 F P-042 | BTC5A (Bis‐Triethylene glycol‐functionalized Crown‐5‐calix[4]Arene) analogs: Phase‐transfer catalysts for Aromatic [18F]fluorination Wonchang Lee1; Seok Min Kang; Dong Wook Kim2; Byung Chul Lee3; Sang Eun Kim4 1
Department of Transdisciplinary studies, Graduate School of
Convergence Science and Technology, Seoul National University, Republic of Korea; 2 Inha University, Republic of Korea; 3 Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea; 4 Seoul National University Bundang Hospital, Republic of Korea
Objectives Fluorine containing compounds particularly aromatic [18F] fluorine labeled radiotracers have an important role in the pharmaceutical field for their high in vivo stability and lipophilicity and also use for PET imaging study. As a result, new labeling methods for effective incorporation of [18F]fluorine into arenes are always in demand. Aromatic nucleophilic substitution, ie, fluorination has been carried out in various precursors containing conventional substituents for aromatic fluorination. Herein, we intend to achieve an effective aromatic fluorination from various precursors by using a new type of phase transfer catalyst (PTC) BTC5A (Bis‐Triethylene glycol‐functionalized Crown‐5‐calix[4]Arene) analogs.1 Methods We prepared six different leaving groups substituted biphenyl precursors (1‐6) for aromatic fluorination. After evaluating the reactivity of precursors in the presence of BTC5A, we have chosen diaryliodonium salt precursors (1 and 2)2 as the
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desirable precursor and optimized the condition of nucleophilic aromatic [18F]fluorination with BTC5A catalyst by changing various solvents, bases, and PTCs. To monitor the stability of the diaryliodonium salts, two diaryliodonium salt precursor was reacted with PTC (K2.2.2/K2CO3 or BTC5A/K2CO3) in various solvents at 120°C for 15 min without the presence of the fluoride ion. Aromatic [18F]fluorinations were conducted with different amounts of PTC complex (K2.2.2/K2CO3 and BTC5A/K2CO3), solvents, radical scavenger (with and without TEMPO), and temperatures by using the diaryliodonium salt precursor (1 or 2) by measuring the radio‐TLC. Results Two diaryliodonium salt precursors (1 and 2) have been synthesized as following the reported method. In the stability test, both precursors showed approximately 30% higher stability in case of BTC5A catalyst compared to K2.2.2 under the same basic condition. After having the stability test, aromatic fluorinations from the biphenyl precursor by using KF with BTC5A were performed in the previous optimized condition (K2.2.2/K2CO3 or BTC5A/K2CO3,DMSO at 120°C for 15 min) and showed that highest yields, up to 64%, is about 20 times higher than K2.2.2 catalyst. In aromatic [18F]fluorine labeling experiments, the radiochemical yield (RCY) in the presence of BTC5A is two times higher (60%) than that in the presence of using K2.2.2. We have also found that RCY was varying (10~61%) by changing the amount of BTC5A and was independent of a radical scavenger, TEMPO as shown Table. Conclusions In this study, we have successfully optimized the condition for aromatic fluorination by using a new type of PTC, BTC5A which is far better (20 times) than commonly use catalyst K2.2.2. With this promising results of fluorine‐18 labeling experiments, we are expecting that BTC5A analogs could be an alternative catalyst providing aromatic [18F]fluorination help to develop new radiopharmaceuticals. Table 1a. Optimization of condition for aromatic fluorination using BTC5A Fluoride Entry Solvent Source
TEMPO Catalyst
RCY (%)
1
DMSO
KF
‐
BTC5A (1.1 eq.)
63.8b
2
DMSO
KF
‐
K2.2.2
2.9b
3
DMSO
18 ‐
‐
BTC5A (1.1 eq.)
10.00
18 ‐
‐
BTC5A (1.1 eq.)
1.58
18 ‐
‐
K2.2.2
nd
18 ‐
‐
K2.2.2
0.30
BTC5A (1.1 eq.)
36.93
4 5 6 7 8 9
DMF DMSO DMF DMSO DMSO DMSO
F ,K2CO3 F ,K2CO3 F ,K2CO3 F ,K2CO3
18 ‐
F ,K2CO3
18 ‐
F ,K2CO3
18 ‐
F ,K2CO3
1 mg ‐
BTC5A (0.55 eq.) 17.22
1 mg
BTC5A (0.55 eq.) 61.54
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Poster Cate gory: Radiochemistry ‐ 18 F P-043 | Rhenium complexation‐dissociation strategy for fluorine‐18 labelling of bidentate PET ligands Mitchell Klenner1; Giancarlo Pascali1; Bo Zhang2; Massimiliano Massi3; Benjamin Fraser4 1
ANSTO, Australia; 2 Australia's Nuclear Science and Technology
Organisation (ANSTO), Australia; 3 Curtin University, Australia; 4 The Australian Nuclear Science and Technology Organisation, Australia
Objectives Pursuant to the discovery that rhenium complexation promotes fluorine‐18 radiolabelling of 1,10‐phenanthroline systems under low temperature, quasi‐aqueous conditions, which circumvent the need for azeotropic drying,1 we expanded our investigation towards thermal decomplexation strategies to improve the radiosynthesis of similar pyridinyl bidentate tracers. Methods Thirty‐eight compounds were synthesised based upon chloro, bromo, nitro, and fluoro substitutions of 1,10‐ phenanthroline, 2,2’‐bipyridine and 8‐hydroxyquinoline
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structures and their respective rhenium tricarbonyl chloride complexes. Each of these compounds, save for the non‐ radioactive fluoro substituted standards, were reacted (>n = 8) under microfluidic conditions with tetraethyl ammonium [18F]fluoride in anhydrous DMSO solvent with increasing reaction temperatures ranging from 50°C to 190°C in 20°C increments. All other parameters such as the precursor quantity, radioactivity, and flow rate/reaction time were kept constant (0.08 μmol, 29 ± 10 MBq, 20 μL·min−1/47 s, respectively). Radiochemical yields (RCYs) for each reaction were then calculated from the Radio‐HPLC peak integrations of the non‐isolated products. Results High RCYs were observed for the [18F]fluoride substitution of rhenium complexed 1,10‐phenanthroline structures (up to 91%) at temperatures ≤90°C, which could prove useful as a novel method for producing PET‐optical tracers given the optical emission properties of rhenium. Good RCYs were also observed for the 2,2’‐bipyridine rhenium complexes, peaking at 84% at 130°C in one example, which then dissociated to form the radiolabelled ligand in 82% RCY at a higher temperature of 190°C, as shown in Figure 1. Radiolabelling of these ligands was unsuccessful under conventional conditions using dry [18F]fluoride, thus establishing rhenium complexation‐dissociation as a novel method for
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radiolabelling. The fluorine‐18 labelling of 8‐ hydroxyquinoline structures was also tested as a means of improving the radiosynthesis of Alzheimer's disease imaging PET tracers such as [18F]CABS13.2 While preliminary rhenium complexation‐dissociation experiments have not yet improved on the radiosynthesis of [18F]CABS13 (5% RCY of ligand & 18% RCY of rhenium complex vs 19±5% RCY of ligand in literature),3 such experiments have enabled the radiosynthesis of related structures, which could not be radiolabelled under conventional conditions using dry [18F]fluoride (eg, [18F]5‐ fluoro‐8‐hydroxyquinoline). Conclusions We report a novel radiofluorination method utilising the rhenium complexation of pyridinyl bidentate structures. This method facilitates radiolabelling of certain analogues of 2,2’‐bipyridine and 8‐hydroxyquinoline structures, which do not radiolabel under conventional conditions. Investigations into monopyridine structures and the development of milder methods of decomplexation are currently ongoing. ACKNOWLEDGMENTS The support of the Australian Institute for Nuclear Science and Engineering (AINSE) is recognised for the kind provision of a postgraduate research award (PGRA), which helped to fund this research. R EF E RE N C E S 1. Klenner, M.A.; Pascali, G.; Zhang, B.; Sia, T.R.; Spare, L.K.; Krause‐Heuer, A.M.; Aldrich‐Wright, J.R.; Greguric, I.; Guastella, A.J.; Massi, M.; Fraser, B.H. Chem. Euro. J. 2017.23, 6499‐6503. 2. Vasdev, N.; Cao, P.; Van Oosten, E.M.; Wilson, A.A.; Houle, S.; Hao, G.; Sun, X.; Slavine, N.; Alhasan, M.; Antich, P.P.; Bonte, F. J.; Kulkarni, P. Med. Chem. Commun. 2012, 3, 1228‐1230. 3. Liang, S.H.; Holland, J.P.; Stephenson, N.A.; Kassenbrock, A.; Rotstein, B.H.; Diagnault, C.P.; Lewis, R.; Collier, L.; Hooker, J. M.; Vasdev, N. ACS Chem. Neurosci. 2015.6, 535‐541.
Poster Cate gory: Radiochemistry ‐ 18 F P-044 | Drying free 18F labeling of phosphate analogues with high stability in vivo Hhongzhang Yang; Zijing Li Center for Molecular Imaging and Translational Medicine, Xiamen University, China
Objectives Phosphate analogues play important roles in both physiological processes and pharmaceutical development, which make themselves potential PET tracers. However, there has been no report that 18F has been labeled
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on phosphate group so far, and the corresponding labeling method remains an open request.1 Herein, to label phosphate group with 18F and protect products from being hydrolyzed through feasible chemistry, precursors (2‐ thio‐1,3,2‐dithiaphospholane), and reference compounds were synthesized. To label and imitate phosphate analogues for tumor imaging, [18F]O‐(((2R,3S,4R,5R)‐5‐(6‐ amino‐9H‐purin‐9‐yl)‐3,4‐dihydroxytetrahydrofuran‐2‐yl) methyl)phosphorofluoridodithioate 4 was designed and labelled as an example to evaluation the accumulation in tumor. Methods Precursors were synthesized starting with 1,1‐dichloro‐N, N‐diethylphosphanamine, followed by nucleophilic substitution using alcohol, finally sulfurization of PIII dithiaphospholane. The corresponding reference compounds were obtained by F‐ nucleophilic substitution and purified by silica gel column chromatography. Precursors were labeled at different times to study the reaction kinetics. Precursors were labeled at different temperatures and reaction solvents for studying the optimum condition of the labeling strategy. Radiolabeling under each condition was repeated at least three times. The radiochemical yields were determined by semipreparative RP‐HPLC. To study adenine nucleotide analogues accumulate in tumor, compound 4 was selected for evaluation in a xenograft tumor–bearing mouse with tumor implanted on the right shoulder. Results Precursor 1 and reference compound 2 were successfully synthesized with high yields and characterized by NMR spectrometry. 18F labeling achieved high radiochemical yield (97%) by nucleophilic substitution in acetonitrile at room temperature with ultrafast reaction speed (in 30 s). Radiolabeling by nucleophilic substitution allowed good separation of the precursor and product, thereby ensuring high specific activity. The ultrahigh reaction efficiency is attributed to low free‐energy barriers of F‐ nucleophilic substitution. Furthermore, the labeling strategy exhibited excellent toleration for water, obtaining satisfactory radiochemical yields when the content of water was between 0% and 20%, which could skip multistep and complex processing procedures of 18F‐ containing azeotropic drying and trapped on QMA. The 18F labeled phosphate analogue demonstrated the excellent stability in PBS, mice serum and healthy BALB/c mice during investigating the metabolic process. Whole‐body PET image of a AR42J tumor–bearing mouse show that [18F]4 specifically accumulated in the tumor. Conclusions An efficient labeling strategy that allows to label phosphate group by 18F with high radiochemical yields was introduced, providing a widely applicable strategy for 18F labeling of phosphate analogues. 18F labeled adenine nucleotide
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exhibited analogues almost identical charge distribution with natural phosphate and have excellent specifical accumulation in tumor. Phosphate analogues can be labeled easily with the labeling strategy, and have great potential to apply in clinical for tumor diagnosis. ACKNOWLEDGMENTS This study was financially supported by the National Natural Science Foundation of China (81501534). R EF E RE N C E S Studenov A R, Adam M J, Wilson J S, et al. Journal Of Labelled Compounds And Radiopharmaceuticals 2005, 48, 497–500.
Poster Cate gory: Radiochemistry ‐ 18 F P-045 | Studies on F2‐free UV photon‐mediated production of [18F]F2 Anna Krzyczmonik1; Merja Haaparanta‐Solin1; Olof Solin1,2 1
University of Turku, Finland; 2 Åbo Akademi University, Finland
Objectives Electrophilic 18F‐fluorination is a useful method for the fluorination of electron‐rich structures such as
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activated aromatic rings or double bonds. The use of electrophilic 18F‐fluorination is limited mostly because of the problematic production of [18F]F2, and the low molar activity that can, in most cases, be obtained with this method. [18F]F2 can be produced in a cyclotron target by irradiating neon or oxygen‐18 enriched oxygen gas, but both of these methods result in very low molar activity and require special gas targets and handling. In 1997, Bergman and Solin presented a method for the production of [18F]F2 from [18F]F‐. The method starts with the synthesis of [18F]MeF from the anhydrous [18F]F‐. Next, [18F] MeF is transfer to a quartz chamber together with carrier F2 and the gas mixture is excited with high voltage electrical discharge.1 Recently, two new modifications of this method have been developed. The first method applies vacuum‐UV photons to promote the isotopic exchange between [18F]MeF and F2, instead of the high voltage discharge.2 The second method uses SF6 as a source of carrier fluorine instead of the toxic F2 for the discharge promoted reaction.3 The aim of the present study is to investigate if the advantages of these two methods 2,3 could be combined for the production of [18F]F2; the use of vacuum‐UV photons and avoidance of F2, Figure 1. Methods [18F]MeF is produced from the dry [18F]KF/K222 complex with MeI in MeCN. After purification by gas
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chromatography, [18F]MeF is collected in a trap held at liquid nitrogen temperature. [18F]MeF is transported into a quartz chamber together with 1% SF6 in neon or xenon. The gas mixture is illuminated with 193 nm photons, generated by an ArF excimer laser. For analysis, the gas mixture is subsequently used for labelling attempts of a model molecule. Results First results indicate that the use of SF6 for vacuum‐UV photon promoted reaction for [18F]F2 does not proceed easily, with no [18F]F2 formed. Similar behavior was previously observed for the discharge promoted SF6 reaction with [18F]MeF 3, which needed much longer discharge time than the original procedure.1 Conclusion Further experiments to confirm the usability of this methods are now ongoing. The use of various fluorine containing carrier gases is explored. ACKNOWLEDGEMENT This study was funded by the European Community's Seventh Framework Programme: FP7‐PEOPLE‐2012‐ ITN‐RADIOMI‐316882 and by a grant from the Academy of Finland (no. 266891). R EF E RE N C E S 1. J. Bergman, O. Solin, Nucl. Med. Biol. 1997; 24, 677 2. A. Krzyczmonik et al., J Labelled Comp Radiopharm. 2017; 60, 186 3. A. Krzyczmonik et al., J Fluor Chem. 2017; 204, 90
Poster Cate gory: Radiochemistry ‐ 18 F
commercialization and favorable half‐life. When labelling biomolecules, incorporation of radionuclide‐tagged prosthetic groups on the biomolecules is the method of choice, since the hash direct labeling with fluorine‐18 is not compatible with protein and peptides. A prosthetic group is labelled and then incorporated into the biomolecule, using mild conditions. One of the most applied prosthetic groups are succinimidyI‐4‐[18F]‐fluorobenzoate ([18F]SFB) obtained in a 3 radioactive steps.1 During the synthesis, a volatile radioactive by‐product is formed. The objective of this study was to simplify the radiosynthesis of [18F]SFB as well as avoiding formation of volatile radioactive by‐products. Methods A novel one step procedure is presented using new precursors that are based on spirocyclic iodonium ylides.2 The radiosynthesis procedure is shown Figure 1. In the presence of the K2CO3 and K222, the precursor was reacted under heating for 4 minutes with the dried [18F] fluoride. [18F]SFB can be purified by different types of SPE or semipreparative HPLC. Results [18F]SFB was obtained in RCY of 10‐15% after purification. [18F]SFB was dissolved in an aqueous buffer and a solution of the peptide/protein/small molecule can be added for labeling. The radiosynthesis was easy to automate, and the synthesis time was less than 50 minutes, including drying of fluorine‐18, labelling and purification. Conclusions A novel feature of the described radiosynthesis of [18F]SFB is that it is a one‐step synthesis (as compared to the usually applied 3‐step synthesis) and reduces its overall complexity. The simpler synthesis is much easier to automate and can thus be implemented on almost all existing automatization devices. In addition, the use of this procedure does not result in the formation of radioactive volatile side products as it is the case for the usually applied 3‐step synthesis and the overall synthesis time is shortened. RE FER EN CES
P-046 | One step synthesis of N‐succidimidyl‐4‐ 18
18
[ F]‐fluorobenzoate ([ F]SFB) Ida Petersen1; Andreas Kjær2; Matthias Herth3; Jacob Madsen4 1
Department of Clinical Physiology, Nuclear Medicine and PET,
University Hospital Copenhagen, Denmark; 2 Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 3 Univesity of Copenhagen, Sweden; 4 Copenhagen University Hospital, Denmark
Objectives Fluorine‐18 is an attractive radionuclide for PET imaging because it can be produced in amounts that allow
1. L. Lang, W. C. Eckelman, Appl. Radiat. Isot. 1994, 45, 1155–116 2. B. H. Rotstein, N. A. Stephenson, N. Vasdev, S. H. Liang, Nat Commun, 2014, 5, 4365
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Poster Cate gory: Radiochemistry ‐ 18 F P-047 | Bis‐triethylene glycolic crown‐5‐calix [4]arene as an efficient phase‐transfer catalyst for nucleophilic radiofluorination with K18F Seok Min Kang; Haebin Kim; Kyo Chul Lee1; Chan Ho Park; Dong Wook Kim2 1
KIRAMS, Republic of Korea; 2 Inha University, Republic of Korea
Objectives Incorporation of fluorine into small molecules has attracted much attention especially in the field of PET (positron emission tomography).1 Most traditional methods of introduction of single fluorine atom into small molecules is nucleophilic aliphatic fluorination with corresponding sulfonate or halide using metal fluoride (eg, KF and CsF). Especially, because of its strong ionic interaction, potassium fluoride (KF) is barely solvated even in polar organic solvent that requires harsh condition like high temperature.2 In this study, we designed and synthesized calix[4]arene based phase transfer catalyst called BTC5A (bis‐triethylene glycolic crown‐5‐calix[4]arene) for nucleophilic fluorination with KF. To validate its practicality in the synthesis of various 18F labeled biomolecules, nucleophilic fluorination of various substrate is successfully conducted with BTC5A in the presence of KF. Method Thirty mCi of fluorine‐18 (produced from [18O]H2O by proton bombardment) in [18O]H2O (0.4 mL) was added to the mixture of BTC5A (40 mg, 0.047 mmol) and K2CO3 (4.9 mg, 0.036 mmol) in glass vial. Subsequently, [18O]H2O was removed by azeotropic distillation with CH3CN (x2) under a stream of nitrogen at 100°C. After complete removal of [18O]H2O, this mixture was transferred to another vial containing 2‐(3‐
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methanesulfonyloxypropoxy)naphthalene (10 mg, 0.036 mmol) by washing with CH3CN (0.5 mL) and stirred at 100°C for 20 min (initial radioactivity was 10.32 mCi). The reaction solution was cooled to room temperature in water bath. Then, radio TLC ratio was confirmed followed by purification step in which elution of reaction mixture with dichloromethane (0.8 mL), EtOAc (4.6 mL) by Plus silica Sep‐Pak was performed to obtain 2‐(3‐[18F]fluoropropoxy)naphthalene. ([18F]21, 7.43 mCi, radio TLC ratio: 100%, decay‐corrected radio chemical yield: 90%, 36 min total reaction time). Results We carried out an F‐18 radiofluorination of model compound 4 with 18F generated by cyclotron under no‐carrier‐added method for PET application of BTC5A. Pleasingly, we obtained desired 18F labeled product [18F]21 in excellent decay corrected radiochemical yield within only 20 min (dcRCY: 90%, radio TLC ratio: 100%, total reaction time: 35 min). After the reaction, BTC5A was successfully removed by short column chromatography. Conclusion We have designed and synthesized BTC5A as a facile aliphatic nucleophilic fluorination promoter with KF. We demonstrated its catalytic system by performing nucleophilic F‐18 radiofluorination to give [18F]21.
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F
P-048 | Organophosphine fluoride acceptors based one‐step
18
F‐labeling in aqueous media
Hhuawei Hong; Rongqiang Zhuang1; HuanHuan Liu; Jindian Li; Hongzhang Yang; Xianzhong Zhang2; Zijing Li3 1
State Key Laboratory of Molecular Vaccinology and Molecular
Diagnostics & Center for Molecular Imaging and Translational Medicine,
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School of Public Health, Xiamen University, China; 2 Xiamen University, China; 3 Center for Molecular Imaging and Translational Medicine, Xiamen University, China
Objectives Currently, only a few 18F‐labeling techniques1,2 can be applied in aqueous media, with non‐macroelement fluoride acceptors and stringent conditions required. Herein, a fast one‐step 18F labeling method through phosphor‐fluorine bond formation in aqueous/organic solvent under room temperature was developed with very high radiochemical yields. Organophosphine fluoride synthons were further conjugated to several peptidic ligands, including c (RGDyk) and HAS, demonstrating intrinsic targeting abilities during imaging. This labeling method offers a more accessible pathway, enabling widespread applications of 18F. Methods Several organofluorophosphine synthons were designed and synthesized. Screening based on in vivo stabilities and kinetic features, di‐tert‐butylphenyl phosphine derivatives (DBPOF) with excellent labeling properties were chosen for radiolabeling of heat‐sensitive biomolecules human serum albumin (HSA) and c (RGDyk) in one step; for labeling, DBPOF‐c (RGDyk) and DBPOF‐HSA was dissolved in an aqueous solution in a glass vial. The aqueous 18F‐ solution from the cyclotron target was trapped on a QMA carbonate ion cartridge then eluted into a reaction vial charged with the unlabeled
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precursor. The vial was gently shaken at room temperature for 5‐15 min and further purified by HPLC or C18 Sep‐Pak Cartridge. Results Radiochemistry of organofluorophosphine fluoride acceptors indicated that di‐tert‐butylphenyl phosphine was rapidly labeled with higher yield and achieved a 100% labeling yield in dimethyl sulfoxide (DMSO) at 75°C. The labeled compound exhibited the highest stability in mice serum, saline, and ethanol, and negligible defluorination in healthy BALB/c mice by investigating the metabolic process. [18F]DBPOF‐c (RGDyk) and [18F] DBPOF‐HAS exhibit excellent stability in vitro. Furthermore, U87 tumor mice and healthy rat were performed with [18F]DBPOF‐c (RGDyk) and [18F]DBPOF‐HSA. Conclusions Here we present a novel method to label biomolecules with 18 F via organofluorophosphine synthons, which can entail a single‐step, very fast, 18F‐labeling reaction in aqueous media and can be easily automated for routine production. ACKNOWLEDGMENTS This study was financially supported by the National Natural Science Foundation of China (81501534). RE FER EN CES 1. Wängler, C.; Kostikov, A.; Zhu, J.; Chin, J.; Wängler, B.; Schirrmacher, R., Silicon‐[18F]fluorine radiochemistry: Basics, applications and challenges. Applied Sciences 2012, 2 (2), 277‐302.
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2. Liu, Z.; Pourghiasian, M.; Radtke, M. A.; Lau, J.; Pan, J.; Dias, G. M.; Yapp, D.; Lin, K. S.; Benard, F.; Perrin, D. M., An organotrifluoroborate for broadly applicable one‐step 18F‐labeling. Angew Chem Int Ed Engl 2014, 53 (44), 11876‐80.
Poster Cate gory: Radiochemistry ‐ 18 F P-049 | Discovery of new ligand for copper mediated [18F]trifluoromethylation from aryl iodides Ji Young Choi1; Shyamsundar Das; Dae Young Bae2; Eunsung Lee2; Byung Chul Lee3; Sang Eun Kim4 1
Seoul National University, Republic of Korea; 2 POSTECH, Republic of
Korea; 3 Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea; 4 Seoul National University Bundang Hospital, Republic of Korea
Objectives Trifluoromethyl group containing drugs have more lipophilicity, in vivo stability and cell wall permeability. For this reason, new methods to introduce a trifluoromethyl moiety into aryl group are very important. Furthermore, [18F]trifluoromethylation is very useful reaction for production of new PET imaging agents.1 In this study, we have tested the various kinds of ligands to find the most efficient ligand for Cu mediated trifluoromethylation (CF3) from aryl iodide. The best ligand, 3,4,7,8‐ tetramethyl‐1,10‐phenanthroline (tmphen), has been used for [18F]trifluoromethylation from various functional group containing aryl iodide. Method In order to find the most efficient ligand, a series of σ‐donor as well as π‐donor ligands were screened and
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the reactivity of these ligands for trifluoromethylation (see Table 1) were compared. We have optimized the reaction conditions with the model substrate 4‐nitro‐1‐ iodobenzene for CF3 substitution in presence of copper iodide, methylchlorodifluoroacetate (MCDFA), potassium fluoride, and ligands. Based on the cold reaction condition, [18F]trifluoromethylation was also performed and compared the radio chemical yield (RYC). Result It has been observed that π‐donor ligands were giving the better yields compare to σ‐donor at the same reaction condition. The most efficient ligand was 3,4,7,8‐ tetramethyl‐1,10‐phenanthroline (tmphen) showed the best yields for trifluoromethylation in cold reaction (35.5 ± 8.4%, n ≥ 3) as well as the highest yields on [18F] CF3 substitution (72 ± 2.0%, n ≥ 3) compared to reported ligand TMEDA (4.7 ± 0.7% and 44 ± 5.8%, n ≥ 3, respectively).2 Finally, the best ligand, tmphen, was used for [18F]trifluoromethylation of various aryl iodide containing sensitive group like, CN, CHO to provide the corresponding [18F]trifluoromethyl substituted arene derivatives. Conclusion In this study, we have explored various ligands on trifluoromethylation to find out the most efficient ligand and gratifyingly tmphen showed the best result compared to all. This methodology has been applied for the synthesis of various [18F]trifluoromethyl substituted arene derivatives and shows good tolerance towards the sensitive group. RE FER EN CES 1. X. Lin, C. Hou, H. Li, Z. Weng. Chem. Eur. J., 2016, 22, 2075 – 2084. 2. M. Huiban, M. Tredwell, S. Mizuta, Z. Wan, X. Zhang, T. L. Collier, V. Gouverneur, J. Passchier, Nat. Chem., 2013, 5, 941–944.
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Poster Cate gory: Radiochemistry ‐ 18 F P-050 | Convenient access to 18F‐labeled amines through the Staudinger reduction Vladimir Shalgunov1; Johanna Steen1; Christoph Denk2; Hannes Mikula2; Andreas Kjær3; Jesper Kristensen4; Matthias Herth5 1
Department of Drug Design and Pharmacology, University of
Copenhagen, Denmark; 2 Institute of Applied Synthetic Chemistry, Technische Universität Wien (TU Wien), Austria; 3 Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Denmark; 4 Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 5
Univesity of Copenhagen, Sweden
Objectives 18 F‐Labeled amines are valuable synthons for the preparation of radiopharmaceuticals.1 Free amino groups are not compatible with direct 18F‐fluorination via traditional nucleophilic substitution methods, so the synthesis of an 18 F‐labeled amine is typically a 2‐step procedure. In 2012, Glaser et al reported preparation of 2‐[18F] fluoroethyl amine through Cu‐mediated reduction of 1‐azido‐2‐[18F]fluoroethane.2 Since 18F‐labeled azides are also popular synthons,1 preparation of 18F‐labeled amines by azide reduction has the advantage that two radiolabeled synthons are synthesized from a single precursor. We aimed to explore the Staudinger reduction [7] as an alternative method for the reduction of 18F‐ labeled azides to amines. The Staudinger reduction can be performed in a homogenous solution, which makes it amenable for automation. Methods Staudinger reduction: 18F‐labeled azides (structures shown in Figure 1) were reacted with triphenylphosphine (5 mg) in dry MeCN for 10 min at 100°C, then 20 mM aqueous NaOH was added to hydrolyze the formed iminophosphorane, the mixture was heated for extra 10 min and let cool down to ambient temperature, affording crude 18F‐labeled amines. Acylation: to the solutions of crude 18F‐labeled amines, benzoyl chloride (1–2 μL, 8.5–17 μmol) was added, and the mixtures were let stand at ambient temperature for 5 min. N‐(2‐(2‐(2‐(2‐[18F]Fluoroethoxy)ethoxy)ethoxy)ethyl) benzamide ([18F]11) was also prepared on an automated synthesis module through Staudinger reduction of the azide [18F]1 with sodium diphenylphosphinobenzene‐3‐ sulfonate (PPh2PhSO3Na) instead of triphenylphospine, and acylation of the crude amine [18F]6 with benzoyl chloride. Radiochemical yields (RCYs) were determined
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by radio‐TLC. Identity of all 18F‐labeled azides, amines, and benzamides was confirmed by co‐elution with 19 F‐references on HPLC and/or TLC. Results Aliphatic and aromatic 18F‐labeled azides were successfully converted to corresponding amines with RCYs ranging from 35% to 84% (Figure 1). In situ acylation with benzoyl chloride gave near quantitative conversion of the obtained amines to the corresponding 18F‐labeled benzamides. Automated synthesis of [18F]11 afforded [18F]11 in 57% radiochemical yield from azide [18F]1 (9% from [18F]fluoride). Conclusions The reduction of 18F‐labeled aliphatic and aromatic azides using triphenylphospine or sodium diphenylphosphinobenzene‐3‐sulfonate proceeded in high RCYs. The amines could successfully be used to prepare a small set of model compounds (benzamides [18F]11‐15) by indirect radiolabeling. Moreover, the procedure was easily automated. We believe that the Staudinger reduction is a valuable tool that can be used to access amino‐functionalized synthons for radiosynthesis of a wide scope of PET tracers. ACKNOWLEDGEMENTS The authors greatly acknowledge the H2020 project Click‐it under grant agreement no. 668532 for financial support and the technical staff at the Department of Clinical 0Physiology, Nuclear Medicine & PET at Rigshospitalet, Denmark. We also thank Placid N. Orji for assistance in the lab.
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R EF E RE N C E S 1. D. van der Born, A. Pees, A.J. Poot, R.V.A Orru, A.D. Windhorst, D.J. Vugts, Chem. Soc. Rev., 2017, 46, 4709–4773. 2. M. Glaser, E. Årstad, A. Gaeta, J. Nairne, W. Trigg, E.G. Robins, J. Label. Compd. Radiopharm., 2012, 55, 326‐331. 3. Y.G. Gololobov, L.F. Kasukhin, Tetrahedron, 1992, 48, 1353‐1406
Poster Cate gory: Radiochemistry ‐ 18 F P-051 | Late stage 18F‐difluoromethylation via a flow photoredox reaction to N‐heteroaromatics. Laura Trump1; Agostinho Lemos2; Bénédicte Lallemand3; Joël Mercier3; Patrick Pasau3; Christian Lemaire4; Andre Luxen5; Christophe Genicot3 1
Global Chemistry,UCB New medicines, UCB Biopharma SPRL, Belgium;
2
University of Liège, Belgium; 3 Global Chemistry, UCB NewMedicines,
UCB Biopharma SPRL, Belgium; 4 Cyclotron Research Center, Universite De Liege, Belgium; 5 Universite De Liege, Belgium
Objectives Up to 50% of the drugs fail in phase 2 and/or 3 due to lack of efficacy, representing a major challenge for pharmaceutical industry. PET (Positron Imaging Tomography) is a powerful non‐invasive imaging technology using radiolabeled molecules for the evaluation of a disease state and for the selection of patients (patient stratification) in clinical trials. For that purpose, 11C and 18F are the most commonly used radioisotopes.1 With a half‐life of 110 minutes (compared to 20 min for 11C), 18F is particularly attractive. However, although CHF2 or CF3 groups are commonly found in drug candidates, only a few methodologies are known for their 18F‐radiolabeling.2–5 Most known methods require a pre‐functionalization step and generally produce compounds with low to moderate molar activity which limits their use in clinical PET imaging. To overcome these limitations, we will report a new flow photoredox methodology for the C‐H insertion of CHF18F on N‐heteroaromatics commonly used in medicinal chemistry. Methods A flow photoredox reaction, allowing to form a CHF18F radical that can be added by C‐H activation on N‐ heteroaromatics compounds.
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Results The reaction has been studied on the acyclovir, an antiherpetic drug. The reaction proceeds fast (within 2 minutes), and allow high radiochemical yield (RCY), up to 70% (based on the crude product). Moreover, this reaction works on a wide range of heteroaromatics (indoles, benzimidazoles, and pyrimidines), tolerates most of the functions present in drugs (nitriles, alcohols, chlorides, and amines) and affords compounds with high molar activity (44.4 −11.1 GBq/μmol). Conclusions We reported a new flow photoredox reaction for the insertion of CHF18F to N‐heteroaromatics. This reaction proceeds fast, by C‐H activation, can be widely applicable, and affords compounds with high molar activity, which makes it promising for later PET studies. ACKNOWLEDGEMENTS This work was supported by funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement N°675071 (ISOTOPICS). RE FER EN CES 1. Preshlock, S., Tredwell, M. and Gouverneur, V. Chem. Rev. 116, 719‐766 (2016). 2. Verhoog, S. et al. Synlett 27, 25‐28 (2016). 3. Shi, H. et al. Angew. Chem. Int. Ed. 55, 10786‐10790 (2016). 4. Yuan, G. et al. Chem. Commun. 53, 126‐129 (2016). 5. Verhoog, S. et al. J. Am. Chem. Soc. 140, 1572‐1575 (2018).
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-052 | Preparation of 18F‐labeled aromatic amino acids by copper‐mediated radiofluorination Johannes Ermert1; Bernd Neumaier2; Boris Zlatopolskiy3; Daniel Modemann4 1
Forschungszentrum Jülich GmbH, Institute of Neuroscience and
Medicine, INM‐5, Nuclear Chemistry, Germany; 2 Forschungszentrum Jülich GmbH, Germany; 3 Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany; 4
Forschungszentrum Jülich GmbH, Institute of Neuroscience and
Medicine, INM‐5, Nuclear Chemistry, Jülich, Germany
Objectives [18F]Fluorophenylamino acids exhibit great potential for diagnostic applications using PET. Nevertheless, their clinical application is still strongly restricted owing to cumbersome production methods. Recently novel transition metal‐mediated 18F‐fluorination methods have
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been introduced into radiochemistry enabling radiofluorination of arenes regardless of their electronic properties.1 The aim of this work was to develop a method for the efficient production of 18F‐labeled aromatic amino acids in high doses by means of alcohol‐enhanced Cu (II)‐mediated radiofluorination of arylboronic acid pinacol esters (PBE).2 Methods The PBE precursors were synthesized by Miyaura borylation of the corresponding N‐BOC protected iodoaromatic amino acid esters. The synthesis of 6‐[18F] FDOPA, L‐2‐[18F]fluorophenylalanine (2‐[18F]FPhe), 6‐[18F]fluoro‐L‐meta‐tyrosine (6‐[18F]FMT) and 5‐[18F] fluoro‐L‐meta‐tyrosine (5‐[18F]FMT) were performed with (py)4Cu(II)(OTf)2 as catalyst. The labeling conditions were optimized with respect to temperature, solvent, and amount of (py)4Cu(II)(OTf)2. The intermediates were purified by SPE and hydrolyzed with HCl affording after HPLC‐purification the desired product. Results The precursors for radiolabeling were synthesized in overall yields of 3 to 17%. The 18F‐labelling reactions were performed using n‐butanol as a co‐solvent improving the RCYs significantly. In the case of 6‐[18F]fluoro‐ L‐3,4‐dihydroxyphenylalanine (6‐[18F]FDOPA), RCY increased from 8% (without the use of n‐butanol for alcohol enhancement) to 40% using alcohol‐enhanced Cu (II)‐mediated radiofluorination. Furthermore, the radiosynthesis of 2‐[18F]FPhe, 6‐[18F]FMT, and 5‐[18F] FMT using boronic acid pinacol esters was transferred to a remote‐controlled synthesis device. High RCYs lead to product activities of 2.4–18.8 GBq enabling preclinical studies. Conclusions The combination of alcohol–enhanced and copper‐ mediated radiofluorination of BPE as labelling precursors was studied with regard to the automated synthesis of several aromatic amino acids. 6‐[18F]FDOPA, 2‐[18F]FPhe, 6‐[18F]fluoro‐L‐meta‐tyrosine (6‐[18F]FMT) and 5‐[18F] fluoro‐L‐meta‐tyrosine (5‐[18F]FMT) were obtained in high
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RCY of 40–66% and up to >99% ee. This enables their synthesis in large amount of radioactivity and high radiochemical and enantiomeric purity, which is necessary for their use in preclinical studies. RESEARCH SUPPORT This work was supported by the DFG grant ZL 65/1‐1.
RE FER EN CES 1. S. Preshlock, M. Tredwell, V. Gouverneur, Chem. Rev. 2016, 116, 719‐766. 2. J. Zischler, N. Kolks, D. Modemann, B. Neumaier, B. D. Zlatopolskiy, Chem. ‐ Eur. J. 2017, 23, 3251‐3256.
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-053 | The use of methanolic solution of tetrabutylammonium tosylate in the preparation of reactive [18F]fluoride and aliphatic radiofluorinations Viktoria Orlovskaya1; Olga Fedorova2; Dmitrii Antuganov3; Raisa Krasikova2 1
N.P. Bechtereva Institute of Human Brain, Russian Academy of Science,
Russian Federation; 2 N.P.Bechtereva Institute of Human Brain, Russian Academy of Sciences, Russian Federation; 3 Almazov National Medical Research Centre, Russian Federation
Objectives Aliphatic nucleophilic SN2 substitution in the presence of kryptofix 2.2.2 or tetrabutyl ammonium hydrocarbonate as phase transfer catalysts (PTC) is currently the most prominent method for production of clinically relevant radiotracers ([18F]FDG, [18F]FET, [18F]FLT). Nucleophilic 18F‐fluorination reactions traditionally include the preceding steps of [18F]fluoride absorption/ elution on the anion exchange resin followed by
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azeotropic drying with acetonitrile. However, this process is associated with radioactivity losses due to radioactive decay of the isotope, its absorption to the walls of the drying vessel and difficulties in automation. Recently several adsorption/elution protocols have been suggested to shorten 18F‐recovery step and, which is more important, to provide less basic and milder 18F‐ fluorination conditions.1,2 Based on these findings, we introduce a new 18F‐processing protocol based on the tetrabutylammonium tosylate (TBAOTs) solution in MeOH and applied it in the synthesis of O‐(2’‐[18F] fluoroethyl)‐L‐tyrosine ([18F]FET) via fluorination of NiII‐complex of an alkylated (S)‐tyrosine Schiff base, Ni‐(S)‐BPB‐(S)‐Tyr‐OCH2‐CH2OTs (I).3,4 Methods QMA Light Sep‐Pak cartridge (130 mg) was pre‐ conditioned with 4 mL of 0.5 M K2CO3 and 10 mL of water. An aqueous [18F]fluoride (1.3 mL) was loaded onto the cartridge from the male side, rinsed with 5 mL of MeOH in the same direction and dried by compressed air. [18F]Fluoride was eluted from the female side with solution of 5 mg of TBAOTs in 1 mL of MeOH. After solvent evaporation, the precursor I (5 mg in 0.8 mL of MeCN) was added, and fluorination was carried out for 8 min at 80°C. The reaction mixture was treated with 0.25 N HCl (120°C, 10 min), then 20 mL of water and 1.6 mL of 0.1 M NaOH were added. The resulting basic solution was passed via two tC18 plus cartridges connected in row. [18F]FET was eluted by 10 mL of NaOAc (5 mM, pH 4) containing 3% of EtOH. Results The replacement of K222/K2CO33,4 with TBAOTs in fluorination of I allowed substantially increase the radiochemical conversion (RCC > 93%, radioTLC) and minimize the radioactivity losses on the walls. The suggested SPE purification procedure afforded [18F]FET in radiochemical purity >99% and enantiomeric purity >95% within 65 min synthesis time. The radiochemical yield (not decay corrected) was 45%. The application of TBAOMs as an inert PTC for radiofluorination of model aliphatic substrates in the protic solvents was earlier reported.2 However, the reaction performance in commonly used acetonitrile suggested in our protocol is preferable for routine production of the radiotracers. The feasibility of new 18 F‐processing protocol was evaluated in the synthesis of [18F]FLT. The RCC was increased from 50 to 85% when switched from K222/K2CO3 to TBAOTs/MeOH using only 10 mg of standard dimethoxybenzyl‐FLT precursor (ABX). Conclusions The use of non‐aqueous solutions and inert bases for the elution of [18F]fluoride gives several advantages in the
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aliphatic radiofluorinations: substantial increase in fluorination efficiency, minimal formation of radiolabelled by‐products, and low radioactivity losses on the inner surfaces. ACKNOWLEDGMENTS This research was supported by RFBR grant 18‐29‐ 01015‐mk 1. H.H. Coenen, J. Ermert, Clin. Transl. Imaging, 2018, 6, 169‐193 2. J. W. Seo et al., Bull. Korean Chem. Soc., 2011, 32(1), 71‐76 3. O. Fedorova et al., J. Radioanal. Nucl. Chem., 2014, 301(2): 505‐512 4. N. Lakshminarayanan et al., Appl. Rad. Isot., 2017, 127, 122‐129
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-054 |
18
F‐Fluorination on natural monophosphate Zhaobiao Mou; Hongzhang Yang; Chao Wang; Zijing Li Center for Molecular Imaging and Translational Medicine, Xiamen University, China
Objectives Natural monophosphate compounds are important participants in physiological process such as metabolism and biological regulation. With analogous van der Waals radius, electronegativity, and valence electron numbers to hydroxyl group, 18F substituted natural monophosphate bearing a P‐18F bond may truly trace phosphate in life activities by positron emission tomography (PET). However, there have been no effective methods for 18F‐fluorinating on phosphate group so far. Herein, a novel 18F‐fluorination method has been developed that provides direct access from natural monophosphate to highly in vivo stable 18F‐fluorinated fluorophosphate via heterocycle prosthesis substitution. Methods Benzyl monophosphate was synthesized as an initial reactant for proof of concept, and imidazole activated benzyl monophosphate as precursor was synthesized. The reference compound was obtained by TBAF in THF and purified by semipreparative RP‐HPLC. 31P NMR was used to monitor whole reaction. This radiolabeling approach employed a nucleophilic substitution of precursor with a 18 ‐ F in aprotic polar solvent in the presence of divalent metal (Zn2+) yielding a 18F‐labeled fluorophosphate, and the radiochemical yield was determined by RP‐HPLC. After radiolabeling, the in vivo stability of 18F‐labeled fluorophosphate was determined by micro PET/CT.
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Objectives
Results The precursor and reference compound were synthesized and characterized by NMR spectrometry. Radiolabeling showed high radiochemical yield (85%) in DMSO at 70°C for 15 min. PET images showed that this 18F‐ labeled fluorophosphate metabolized through the kidneys and no obvious radio‐signal accumulation in the skeleton of the mice was observed in 60 min. This result is noteworthy because it is the first demonstration that designed 18F‐labeled fluorophosphate can be imaged in vivo without major hydrolytic defluorination. Conclusion An effective radiolabeling approach was developed that natural monophosphate was chose as initial reactant and 18 F‐fluorinated fluorophosphate was obtained via prosthesis substitution by one‐step activated monophosphate. This method would be applied to radiolabel more bioactive monophosphates as potential PET probes. ACKNOWLEDGMENTS This study was financially supported by the National Natural Science Foundation of China (81501534). R EF E RE N C E S 1. Baranowski, M.R.; Nowicka, A.; Rydzik, A.M.; Warminski, M.; Kasprzyk, R.; Wojtczak, B.A.; Wojcik, J.; Claridge, T.D.W.; Kowalska, J.; Jemielity, J. J. Org. Chem. 2015, 80, 3982–3997.
Poster Cate gory: Radiochemistry ‐ 18 F P-055 | Explorations towards the chemical scope of [18F]triflyl fluoride, a new gaseous [18F]fluoride source Lizeth Haveman1; Anna Pees2; Danielle Vugts2; Albert Windhorst1 1
VU University Medical Center, Netherlands; 2 Amsterdam UMC, VU
University, Netherlands
Fluorine‐18 is the predominant radionuclide used for Positron Emission Tomography (PET) tracer synthesis. The continued growth of fluorine‐18 applications requires new, fast, and efficient synthetic methodologies for (automated) radiopharmaceutical production using cyclotron‐ produced aqueous [18F]fluoride. Recently, our lab developed a versatile strategy for the production of reactive [18F]fluoride from aqueous [18F]fluoride in less than 5 minutes with 90% radiochemical yield using gaseous [18F]triflyl fluoride.1 This approach not only omits time consuming azeotropic drying procedures but also opens the possibility to individually tailor the type and amount of base needed in the subsequent radiofluorination reaction, an important prerequisite for recently reported radiofluorination techniques. Our objective was to investigate its application in fluorine‐18 aromatic nucleophilic substitution reactions using iodonium ylid precursors, phenols, and pinacol‐derived aryl boronic esters. Methods Gaseous [18F]triflyl fluoride was formed at room temperature from hydrated [18F]fluoride, followed by distillation and trapping in a dry aprotic solvent. Unless stated otherwise, the [18F]fluoride was released from [18F]triflyl fluoride in the presence of 0.36 μmol K2CO3 and 0.86 μmol K222 after which the precursor was added. The Cu (II)‐ mediated 18F‐fluorination of 1 was performed in 800 μL of DMF with 60 μmol of 1 and 5.3 μmol of [Cu (OTf)2(py)4] at 110° C for 10‐20 min. The [18F]deoxyfluorination of 2 was performed at 110°C for 20 min with 8.7 μmol of 2, 8.7 μmol of 4, and 4.4 μmol of Ag2CO3. The used solvents included 600 to 900 μL DMF, toluene, 2‐butanone: EtOH (10:1) or mixtures of them. The radiofluorination of 3 was performed in 700 μL of DMF with 4.4 μmol of 3 at 120°C for 5‐10 min. For this reaction, the release of [18F] fluoride was also attempted in the presence of 77 μmol Et4N.HCO3. Aliquots of the reaction mixture were taken to determine the yield of the 18F‐labeled products by HPLC, mounted with UV radiodetection using a Phenomenex Luna C18 column (5 μm, 4.6 × 250 mm) and H2O/ MeCN (1: 45/55 and 2: 60/40) as eluent at a flow rate of 1 mL/min and a wavelength of 254 nm. An Alltima C18 column (5 μm, 4.6 × 250 mm) and H2O + 0.1% TFA/MeCN + 0.1% TFA (50–95%) as eluent were used for the analysis of 3. In addition, reaction mixtures were also analyzed with TLC (Merck F254 silica) using a phosphorimager to read out the radioactivity. Results and Discussion [18F]Fluorobenzene could be synthesized from 1 upon reaction with [18F]triflyl fluoride and [Cu (OTf)2(py)4]. This otherwise base‐sensitive reaction was performed with extremely reduced amounts of base and cryptand, respectively 0.36 and 0.86 μmol. The radiofluorination
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reaction was completed in 20 minutes with a yield of 83 ± 3% (n = 2) as determined by radioHPLC. For the [18F]deoxyfluorination of 2, reagents 2, 4, and Ag2CO3 in toluene were added at once to the trapped dry [18F] fluoride in DMF, omitting the laborious work‐up procedure and precursor synthesis as published by Neumann et al.2 Under these conditions, an excellent selectivity for the [18F]4‐fluorobenzaldehyde was observed with a yield of 52% (n = 1). Further improvements are anticipated upon optimization of the reaction conditions. Finally, radiofluorination of 3 could be achieved in low yields (98% RCP and 7% non‐isolated RCY. Final HPLC purification is ongoing. Radiofluorination of the activated phenol resulted in 60% conversion rate using KHCO3 as base in butanone: EtOH (10:1) at 130°C for 10 minutes, further investigations of this method are in progress. Conclusion Two original precursors for the radiofluorination of crizotinib were successfully synthesized, and 18F‐ crizotinib was radiolabeled from the spirocyclic hypervalent iodine precursor in good yields and high purity. Purification conditions are currently being explored to assess ready‐to‐inject 18F‐crizotinib, which will be used as a radiotracer to explore the ABCB1 function at the blood brain barrier in rodents with PET imaging. ACKNOWLEDGEMENT The authors thank the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement No 675071 for funding the project. R EF E RE N C E S 1. Chuan Tang, S. et al. Int. J. Cancer 2014; 134, 6; 1484–1494.
Poster Cate gory: Radiochemistry ‐ 18 F P-057 | Investigation of the metabolic stability of new silicon‐based fluoride acceptor tracers
18
F‐
Sonja Sofia Otaru1; Surachet Imlimthan2; Kerttuli Helariutta2; Kristiina Wähälä2; Mirkka Sarparanta2; Anu Airaksinen2
1
Department of Chemistry, University of Helsinki, Finland; 2 University of
Helsinki, Finland
Objective Silicon‐fluoride‐acceptor (SiFA) labeling methodology has been proven to be a convenient tool for the radiolabeling of biomolecules with fluorine‐18 via a (19F/18F)‐isotopic exchange (IE) in mild reaction conditions.1 (19F/18F)‐IE has been applied for the labeling of small and large molecules with success, and evidence support the applicability of SiFA‐labeling especially for the 18F‐fluorination of in vivo‐stable biomacromolecules and nanoparticles.2,3 To this day, only a few studies exist of the in vivo stability of a radiolabeled small molecule SiFA‐tracer.4 Methods To utilize the efficient (19F/18F)‐IE‐method for radiolabeling, we have designed a new SiFA‐tetrazine‐ radiotracer (SiFATz) suitable for bioorthogonal in vivo and in vitro labeling methods. Because of the lack of information about the in vivo stability of small SiFA‐tracers, we tested both new radiotracers, the [18F]SiFATz and [18F] fluoroalbumin, in an ex vivo biodistribution studies. [18F] Fluoroalbumin was prepared using the biorthogonal inverse electron‐demand Diels‐Alder (IEDDA) reaction in vitro, as a proof‐of‐principle protein for the in vitro radiolabeling of proteins with [18F]SiFATz. A new tetrazine functionalized silicon‐based fluoride acceptor small molecule tracer (SiFATz) was synthesized with multistep synthesis and characterized with 1H‐, 13C‐, 19F‐, and 2D‐NMR, ESI‐TOF MS. The radiolabeling of the new SiFATz tracer was carried out in two‐steps; first, the prosthetic group SiFA was radiolabeled with, followed by an oxime formation with tetrazine. The oxime formation
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between [18F]SiFA and the aminooxy functionalized precursor SiFATz was completed at RT within 15 minutes. Then the product was further purified with HPLC (0.01M H3PO4:EtOH, 75:25 v/v). The formulated radiotracer [18F]SiFATz was used as such or incubated for 2 minutes with albumin‐TCO in 0.01 M PBS (pH 7.4) forming [18F]fluoroalbumin. Results The radiolabeling yield for SiFATz was high (99%, non‐ decay corrected yield). The oxime formation between [18F]SiFA and the aminooxy‐Tz yielded 74% of [18F] SiFATz of the total radioactivity (non‐decay corrected yield). The yield of the HPLC‐purified [18F]SiFATz was 35% (decay corrected yield to end of bombardment) with a total synthesis time of 148 minutes. Molar activity of the final product [18F]SiFATz was 7 GBq/μmol. [18F]SiFATz (10.8 ± 1.2 MBq, 47 nmol) or [18F]fluoroalbumin (0.4 ± 0.2 MBq, 0.7 nmol) was intravenously administered to healthy female Crl:CD‐1 mice for biodistribution studies. The excised tissue samples were analyzed with gamma counting, radio‐HPLC and radio‐TLC. The high bone uptake of radioactivity detected for [18F]SiFATz was diminished substantially when bound to albumin, demonstrating significant improvement in the stability of the 18F‐label in the SiFa‐moiety in vivo within the model biomolecule. Conclusions We have developed a radiolabeling method of biomolecules with [18F]SiFATz, using albumin as a model protein. We were also successful in demonstrating the enhanced stability of a tetrazine‐functionalized SiFA‐compound while bound to a biomolecule, compared to its stand‐alone stability as small molecule. We herein report a new 18F‐ radiolabeled small molecule tracer suitable for the radiolabeling of TCO‐functionalized biomolecules. ACKNOWLEDGEMENTS This project has been supported by The Academy of Finland with decision numbers 306239, 278056, 298481 and by a University of Helsinki three‐year research grant. R EF E RE N C E S 1. R. Koudih, A. Kostikov, M. Kovacevic, D. Jolly, V Bernard‐ Gauthier, J. Chin, K. Jurkschat, C. Wängler, B. Wängler, R. Schirrmacher, Applied Radiation and Isotopes, 2014, 89, p. 146–150. 2. S. Berke, A. L Kampmann, M. Wuest, J. J. Bailey, B. Glowacki, F. Wuest, K. Jurkschat, R. Weberskirch, R. Schirrmacher, Bioconjugate Chem. 2018, 29, p. 89−95. 3. J. Zhu, J. Chin, C. Wängler, B. Wängler, R. B. Lennox, R. Schirrmacher, Bioconjugate Chem. 2014, 25, p. 1143−1150. 4. Y. Joyard, R. Azzouz, L. Bischoff, C. Papamicaël, D. Labar, A. Bol, V. Bol, P. Vera, V. Grégoire, V. Levacher, P. Bohn, Bioorg. Med. Chem. 2013, 21 (13), p. 3680‐3688.
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P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-058 | Radiosynthesis of [18F]mFBG on Trasis AllinOne for PET imaging in children with neuroendrocrine malignancies Emilie Da Costa Branquinho1; Julien Fouque1; Marie Luporsi2; Claire Beauvineau3; Thibaut Cassou Mounat2; Sandy Blondeel‐Gomes1; Olivier Madar1 1
Department of Radiopharmacology, Institut Curie, France; 2 Department
of Imagery, Nuclear Medicine Unit, Institut Curie, France; 3 Research center, CMIB, UMR9187/U1196, Institut Curie, France
Objectives [123I]meta‐iodobenzylguanidine ([123I]mIBG) is a well‐ known SPECT radiotracer used in the evaluation of neuroendocrine malignancies, such as neuroblastoma, one of the most common childhood cancer. Unfortunately, it requires a 24 h uptake time and thyroid blockade and lead to poor image resolution, compared to PET radiotracers. In order to improve patient care, especially with children, it was decided to produce [18F]meta‐ fluorobenzylguanidine ([18F]mFBG), a promising PET radiofluorinated analog of [123I]mIBG. Methods [18F]mFBG was prepared on a AllinOne (Trasis) synthesis module according to GMP regulation and a slightly modified procedure from Preshlock et al.1 In a two steps automated process, nucleophilic radiofluorination of an aryl boronate ester precursor, using a copper catalyst, was followed by removal of Boc protecting groups to afford a crude solution of the radiotracer. After purification of on an online semi‐preparative HPLC, [18F]mFBG was formulated in saline and filtered through a 0.22 μm sterile membrane. Results Optimal labeling conditions were achieved at 120°C for 10 minutes, using 5 mg of precursor in anhydrous N,N‐ dimethylacetamide. [18F]mFBG was afforded within 52 ± 2 minutes, in 21‐25% radiochemical yield (n > 10) after HPLC purification and formulation. Radiochemical purity was greater than 99%, as determined in UPLC® (Waters) and radio‐TLC. Specific radioactivity was >100 GBq/μmol at the end of synthesis (EOS). No residual solvent was found in the final product. Conclusions The fully automated synthesis of [18F]mFBG including labeling, deprotection, HPLC purification, and formulation was optimally carried‐out on an AllinOne synthesizer. The radiotracer was afforded in high chemical and
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radiochemical purity, ready for clinical use. The formulation, exempt from residual solvents, makes it suitable for administration in children suffering from neuroendocrine malignancies. R EF E RE N C E S 1. Preshlock et al. Chem. Commun. 2016, 52, 8361‐8364.
Poster Cate gory: Radiochemistry ‐ 18 F P-059 | 2‐[18F]Fluoro‐5‐iodopyridine ([18F] FIPy): A novel reactive prosthetic group for the fast site specific radiolabeling via Pd‐catalyzed cross coupling reactions Mohamed Aymen Omrane1; Boris Zlatopolskiy2; Bernd Neumaier3 1
Forschungszentrum Jülich GmbH, Institute of Neuroscience and
Medicine, INM‐5: Nuclear Chemistry, Jülich, Germany. Department of Nuclear Medicine, University Medical Center Freiburg, and Division of Radiopharmaceutical Development, German Cancer Consortium (DKTK), partner site Freiburg, Germany; 2 Institute of Radiochemistry and Experimental Molecular Imaging (IREMB), University Hospital of Cologne, Germany; 3 Forschungszentrum Jülich GmbH, Germany
Aim Numerous Pd‐catalyzed cross‐couplings like Sonogashira, Suzuki‐Miyaura, Heck, and Stille reactions proved to be
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valuable tools for the site specific labeling of biopolymers. The aim of this work was the study of Pd‐catalyzed cross coupling reactions using [18F]FIPy as radiolabeled synthon and 2,2′‐(1,2‐phenylene)‐bis‐(4,4‐dimethyl‐4,5‐ dihydrooxazole)‐N,N′‐palladium dichloride (Pd‐BOX‐1) as catalyst. Pd‐BOX‐1 demonstrated exceptional air and moisture stability and excellent catalytic activity in aqueous reaction media. Methods The direct reaction of 2‐bromo‐5‐iodopyridine with DABCO followed by anion metathesis using TMSOTf afforded 1‐(5‐iodopyridin‐2‐yl)‐1,4‐diazabicyclo[2.2.2] octan‐1‐ium triflate (1) used as precursor for the preparation of [18F]FIPy. The latter was produced using the “minimalist” protocol. Accordingly, [18F]fluoride was eluted from a QMA cartridge with a solution of 1 in MeOH. MeOH was evaporated at 45°C (250 mbar) within 4 min, DMSO was added, and the resulting solution was heated affording [18F]FIPy, which after the purification by SPE was conjugated to different model compounds by different Pd‐catalyzed (1% of Pd‐BOX‐1) cross‐couplings using aqueous MeCN or DMF as reaction solvent within 10 min. Results 18 – F recovery from an anion exchange resin using 1 (3 mg) amounted >98%. Heating of the resulting [18F] fluoride onium salt in DMSO at 100°C for 15 min afforded [18F]FIPy in excellent radiochemical conversions (RCCs) of 91 ± 3%. [18F]FIPy was isolated in 61 ± 5% radiochemical yield (RCY) and excellent radiochemical purity (RCP) of >98%. The subsequent Cu and phosphine free Pd‐BOX‐1 catalyzed Sonogashira cross‐coupling with phenylacetylene afforded the corresponding conjugate in an excellent RCC of >89%. Furthermore, Suzuki‐
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Miyaura, Heck, and Stille reactions with 4‐methylphenyl boronic acid, methyl acrylate, and trimethyl (phenyl)tin, respectively, applied as model coupling partners furnished the corresponding radiofluorinated conjugates in RCCs of 85–98%. Conclusion [18F]FIPy is a valuable radiolabeled prosthetic group easily accessible using the “minimalist” approach. Various Pd‐BOX‐1‐catalyzed cross coupling reactions with [18F]FIPy is a versatile procedure for a fast, high‐yielding, and site specific radiolabeling under relatively mild conditions.
Poster Cate gory: Radiochemistry ‐ 18 F P-060 | [18F/19F] Isotopic exchange radiolabeling of pentafluorosulfanyl groups Hugh Hiscocks1; James Hill2,5; Giancarlo Pascali3,6; Peter Scott4; Allen Brooks2; Alison Ung1 1
University of Technology Sydney, Australia; 2 University of Michigan,
United States; 3 ANSTO, Australia; 4 The University of Michigan, United States; 5 University of Queensland, Australia; 6 University of Sydney, Australia
Objective The pentafluorosulfanyl (ie, ‐SF5) moiety is attracting increased interest in medicinal chemistry since being reported as a trifluoromethyl bioisostere.1 Recent literature has highlighted the utility of Si‐F, B‐F, and Al‐F bonds in PET radiochemistry.2,3 S‐F bonds, however, remain relatively unexplored with the exception of sulfonyl fluorides (i,e ‐SO2F), which exhibit debatable stability in vivo.4,5 Currently, there are no reports of radiolabeled pentafluorosulfanyl groups. We propose that the ability to radiolabel SF5 groups would be a valuable expansion to the existing fluorine‐18 radiochemical space, facilitating the development of new PET tracers. Methods We investigated 18F/19F isotopic exchange reactions of SF5‐containing structures under both microfluidic and batch synthesis conditions. Commercially available precursors and synthesized novel amino acid derivatives
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were treated with [18F]Et4NF/HCO3, and RCC was determined via radio‐HPLC and/or TLC. Scheme 1. 18F/19F exchange of m/p‐nitro‐pentafluorosulfanylbenzene Results 18 19 F/ F isotopic exchange was successful on nitro substituted (meta or para) aromatic SF5 compounds in 5‐60% RCC (Table 1). Amine and aldehyde‐substituted aromatic SF5 compounds did not undergo radiolabeling using either of the radio‐synthetic conditions employed. Amino acid analogues bearing a p‐pentafluorosulfanylbenzene substituent, gave low RCC (98% RCP and high Am (0.80 ± 0.25 Ci/μmol, n = 3); qualification of the synthesis for preclinical use is underway. Conclusions We successfully developed the method for Cu‐mediated, aminoquinoline directed Csp2‐H radiofluorination of arenes with K18F, and this method has been applied to
a variety of carboxylic acid‐derived substrates including the active pharmaceutical ingredients of probenecid, ataluren, and tamibarotene. In addition, it was translated to the automated synthesis of high specific doses of RARβ2 agonist [18F]AC261066. Overall, this operationally simple process holds great potential for the late‐stage radiofluorination of bioactive molecules. ACKNOWLEDGEMENTS This work was supported by NIH (R01EB021155) and DOE (DE‐SC0012484). RE FER EN CES T. Truong et al, J. Am. Chem. Soc. 2013, 135, 9342 H.H. Coenen et al. Nucl. Med. Biol. 2017, 55, v‐xi
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-064 | Radiofluorination of pyridinyl iodonium salts for the preparation of 3/5‐[18F] fluoropyridines: Optimization, mechanism investigation and scope Cecile Perrio2; Mathilde Pauton; Catherine Aubert1,2; Guillaume Bluet2; Florence Gruss‐Leleu2; Sébastien Roy2
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Normandie University, France; 2 Sanofi, France
Objectives The pyridine moiety is encountered in numerous drugs. Although advantageous for stability, introduction of [18F]fluorine atom at positions 3 or 5 remains challenging.1–4 Iodonium salts are known to allow late‐stage radiolabeling of arene free of electron‐withdrawing group for activation.1 They have also been proved to be useful in rapid process under “minimalist” conditions.3 However, exploitation of 3/5‐pyridinyl iodonium salts is poorly reported. To our knowledge, [18F]UCB‐H is the sole example of 3/5‐[18F]fluoropyridine‐based radiotracer obtained by radiofluorination of a pyridinium iodonium salt.4c The radiosynthesis, performed in the presence of TEMPO as radical scavenger, was compatible with cGMP production. Herein, we report a detailed study of the radiofluorination of pyridinyl iodonium salts in the presence of TEMPO including optimization, mechanism investigation, and scope. Methods We prepared a series of pyridinyl iodonium salts (tetrafluoroborates, bromides, tosylates, or triflates) bearing electron donor or withdrawing substituents from the corresponding iodopyridines and anisole, mesitylene, or thiophene. Radiofluorination reactions were performed in different solvents (ACN, DMF, or DMSO) for 10 to 60 min, at temperatures between 85 and 150°C, in the presence of TEMPO (0‐5 equiv) and K2CO3, using conventional [18F]KF‐K2.2.2 complex or under minimalist conditions (Figure 1). [18F]Fluoropyridines were identified by coelution with reference compounds on analytical HPLC. RCYs were determined after purification on semi‐ preparative HPLC. Results Efficiency of radiofluorination reaction was strongly dependent on the starting iodonium salts and the amounts of TEMPO and K2CO3. Both conventional and minimalist conditions were compatible with radiofluorination. K2CO3 was found to be essential for radiofluorination, but the amount could be minimized under minimalist conditions. The optimal RCYs (24‐ 83%) were obtained by treatment of pyridinyl iodonium triflates containing an anisole group in the presence of TEMPO (1 or 3 equiv, depending on the amount of
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K2CO3) in DMF at 130°C for 30 min or in ACN at 90°C for 15‐30 min. Conclusion Radiofluorination of pyridinyl iodoniums in the presence of TEMPO was revealed to be useful for the synthesis of a wide range of 3/5‐[18F]fluoropyridines. The obtained results offer new opportunities for the development of innovative PET radiopharmaceuticals. ACKNOWLEDGEMENTS We thank the ANRT (Association Nationale de la Recherche et des Technologies), CIFRE grant 2015/0665. RE FER EN CES 1. Preshlock, S.; Tredwell, M.; Gouverneur, V. Chem. Rev. 2016, 116, 719‐766. 2. (a) Narayanam, M. K.; Ma, G.; Champagne, P. A.; Houk, K. N.; Murphy, J. M. Angew. Chem. Int. Ed. 2017, 56, 13006‐13010. (b) Taylor, N. J.; Emer, E.; Preshlock, S.; Schedler, M.; Tredwell, M.; Verhoog, S.; Mercier, J.; Genicot, C.; Gouverneur, V. J. Am. Chem. Soc. 2017, 139, 8267‐8276. (c) Neumann, C. N.; Hooker, J. M.; Ritter, T. Nature 2016, 534, 369‐373. (d) Chun, J. H.; Morse, C. L.; Chin, F. T.; Pike, V. W. Chem. Commun. 2013, 49, 2151‐2153. (e) Rotstein, B. H.; Stephenson, N. A.; Vasdev, N.; Liang, S. H. Nat. Commun. 2014, 5, 4365‐4371. (f) Petersen, I. N.; Kristensen, J. J.; Herth M. M. Eur. J. Org. Chem. 2017, 453‐458. (g) Gendron, T.; Sander, K.; Cybulska, K.; Benhamou, L.; Brian Sin, P. K.; Khan, A.; Wood, M.; Porter, M. J.; Årstad, E. J. Am. Chem. Soc. 2018, 140, 11125‐11132. 3. Richarz, R.; Krapf, P.; Zarrad, F.; Urusova, E. A.; Neumaier, B.; Zlatopolskiy, B. D. Org. Biomol. Chem. 2014, 12, 8094‐8099. 4. (a) Chun JH, Pike VW, Chem. Commun. 2012, 48, 9921‐9923. (b) Carroll MA, Woodcraft J, WO2007141529 A1. (c) Warnier, C.; Lemaire, C.; Becker, G.; Zaragoza, G.; Giacomelli, F.; Aerts, J.; Otabashi, M.; Bahri, M. A.; Mercier, J.; Plenevaux, A.; Luxen, A. J. Med. Chem. 2016, 59,19,8955‐8966. (d) Liu, H.; Liu, S.; Miao, Z.; Deng, Z.; Shen, B.; Hong, X.; Cheng, Z. J. Med. Chem. 2013, 56, 895‐901.
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-065 | Aryltrialkylstannanes are viable substrates for [18F]trifluoromethylation Bo Yeun Yang1; Sanjay Telu1; Xiaofei Zhang2; Steven Liang3; Victor Pike1 1
National Institute of Mental Health, United States; 2 MGH/Harvard,
China; 3 MGH/Harvard, United States
Objectives Trifluoromethyl groups can be attractive sites for carrying radiolabels in PET radiotracer development because of their expected resistance to metabolism. The introduction of [18F]trifluoromethyl groups into aryl or heteroaryl groups using CuCF218F as reagent has been recently
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demonstrated on various substrates, including arylboronic acids,1 iodoarenes,2,3 and diaryliodonium salts. However, aryl and heteroaryl trialkylstannanes have not previously been examined for this purpose, despite their synthetic accessibility and versatility. In this pilot study, we tested whether aryltrialkylstannanes were viable substrates for [18F]trifluoromethylations. Methods We produced [18F]fluoroform in the gas phase as earlier reported,4 except that [18F]fluoromethane was purified with gas chromatography before difluorination over heated cobalt trifluoride. [18F]Fluoroform was trapped in cold (–41°C) DMF (600 μL). Cu(t‐BuO)/DMF was prepared under dry nitrogen atmosphere, and [18F] fluoroform in DMF (100‐200 μL) was added to produce CuCF218F, which was then stabilized with Et3N.3HF in DMF (1.64%, 50 μL) before addition of trialkylstannyl substrate (50 μmol) in DMF (100 μL). Air (~10 mL) was bubbled through the solution, which was then shaken vigorously and kept at RT for 10 min. The reaction was quenched with MeCN:H2O (1:1 v/v) and the mixture passed through a PTFE syringe filter (0.2 μm). The identities and yields of [18F]trifluoromethylated products were determined with reverse‐phase radio‐HPLC. Results [18F]Fluoroform was produced in ~35% yield from [18F] fluoromethane and with >97% radiochemical purity. Among homoaryl substrates, trimethylstannylbenzene and tri‐n‐butylstannylbenzene gave [18F] trifluoromethylbenzene in high yields (>62%) (Table 1
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entries 1 and 2, respectively). Substrates with a p‐electron‐ withdrawing group gave moderate to high yields (71% for p‐CN, 47% for p‐COOEt) (Table 1, entries 3 and 4). Pyridinyltrialkylstannanes gave low yields (9‐24%, entries 5‐8). (Phenylthynyl)tri‐n‐butylstannane, although giving a low yield, was also found to be a viable substrate (Table 1, entry 9). Conclusions Aryltrialkylstannanes are viable substrates for rapid [18F] trifluoromethylation. Further studies are required to optimize the reaction procedure for higher yields and to determine its full scope and reliability. ACKNOWLEDGMENTS This work was supported by IRP of NIH (NIMH). RE FER EN CES 1. Ivashkin P. et al. Chem. Eur. J., 2014, 20, 5914‐9518. 2. Van der Born D. et al. Angew. Chem. Int. Ed. 2014, 53, 11046. 3. Rühl T. et al. Chem. Commun., 2014, 50, 6056. 4. Yang BY et al. J. Label. Compd. Radiopharm., 2017: 60 (Suppl. 1): S263.
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-066 | A Combinatorial Library of Fluorine‐Integrated Peptides for PET Imaging Agent Discovery Emily Murrell; Leonard Luyt University of Western Ontario, Canada
Objectives One‐bead one‐compound (OBOC) libraries are a combinatorial method of synthesizing libraries of distinct peptide sequences on individual resin beads. This methodology has been applied to drug discovery by screening the millions of peptide‐bearing beads for interactions with specific receptors. As with many high‐throughput screening options, this method is not easily transferrable to the discovery of novel imaging agents since standard libraries do not include an imaging moiety; post‐screening modifications of hits to add imaging moieties often interrupts the binding interaction discovered. We sought to integrate a 19 F‐moiety into the structure of each entity in an OBOC library, allowing for the screening to be performed on complete imaging agents, where the imaging moiety is included in ligand‐target interaction. We developed a new 18F‐labelled cyclooctyne prosthetic group that is compatible with copper‐free click chemistry and is designed for
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integration into an azide‐containing amino acid side chain.1 The 19F‐analogue of this prosthetic group was synthesized and used in the construction of the OBOC library. Methods An eight amino acid OBOC library was created on a photocleavable linker on Tentagel resin through solid‐ phase peptide synthesis and the use of a split and mix technique. An Fmoc‐protected lysine azide amino acid was introduced into the library as a point of attachment for our fluorine‐containing prosthetic group. To ensure that a single fluorine‐containing amino acid would be included in each peptide sequence only once, the library was synthesized using diverging and converging pools accompanying the split‐and‐mix steps (Figure). After eight amino acids were coupled to each bead, the entire pool was exposed to the 19F‐modified azadibenzocyclooctyne to afford the clicked products. Results The result of this synthetic scheme is a peptide library where the imaging entity is evenly distributed among the eight positions in the peptide sequence on each bead, and the remainder of amino acids in the sequences are randomized. The success of the library synthesis was validated by subjecting random beads to MALDI tandem mass spectrometry and verifying the presence and sequence of eight amino acid residues including one with our imaging surrogate. This combinatorial library is being used to screen for affinity to CXCR4, a cancer biomarker of interest. The screening approach checks for target affinity and specificity by using multiplexed, colour‐coded, dye‐labelled cells. Together, a U87 cell line transfected to overexpress CXCR42, along with the parent cell line, were incubated with the library pool of beads. Through fluorescence microscopy, beads that showed
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binding to only the CXCR4‐expressing cells were isolated. The peptides were detached from the beads by UV light, and their respective peptide sequences are identified by MALDI tandem mass spectrometry. Conclusions This unique combinatorial library of fluorine‐containing peptides was used to discover potential PET imaging agents for CXCR4. The peptides corresponding to initial hits from the library screen can be further studied to assess their CXCR4 affinity and subsequently easily translated into cancer imaging probes by replacing the 19F‐moiety in each hit with our 18F‐radiolabelled prosthetic group. This novel type of OBOC library can be used to screen against various targets to discover new 18F‐based PET imaging agents. In addition, any appropriate alkyne‐based imaging moiety could be clicked into such libraries at the lysine‐azide residue to afford OBOC libraries for a wide variety of imaging applications. ACKNOWLEDGEMENTS National Sciences and Engineering Research Council of Canada (NSERC) The following reagents were obtained through the NIH AIDS Reagent Program, Division of AIDS, NIAID, NIH: U87.CD4.CXCR4, U87.CD4 from Dr. HongKui Deng and Dr. Dan R. Littman. We also thank the Molecular Imaging Collaborative Program at the University of Western Ontario.
RE FER EN CES 1. Murrell, E.; Kovacs, M. S.; and Luyt, L. G. ChemMedChem. 2018, 13, 1625‐1628. 2. Björndal, A.; Deng H.; Jansson, M.; Fiore, J. R.; Colognesi, C.; Karlsson, A.; Albert, J.; Scarlatti, G.; Littman, D. R.; and Fenyo, E. M.; J. Virol. 1997, 71, 7478–7487.
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Poster Cate gory: Radiochemistry ‐ 18 F P-067 | A novel PET probe for in vivo imaging of free radical species Vamsidhar Akurathi1; Lindsey Floryance1; Vijay Pawar2; Claire North1; David Dick1 1
University of Iowa, United States; 2 Synthink Research Chemicals, India
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Objective Free radical species have been implicated in the pathophysiology of pancreatitis, traumatic brain injury, cancer, and neurological disorders.1,2 Obtaining in vivo spatial information of free radical species through [α‐(4‐Pyridyl N‐oxide)‐N‐tert‐butylnitrone] (POBN) is a powerful tool for tracing free radical species. However, the spin traps that formed radical adducts often susceptible to bio‐ reduction and converts adducts to electron spin resonance silent species. Additionally, the equipment used
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for spin trapping is limited to small samples and cell studies. Thus, a novel method for imaging free radicals in vivo is still needed. We hypothesize that by attaching F‐18 to POBN, we can use [18F]3‐fluoro‐4‐POBN as a free radical spin trapping probe analog, providing a practical route for positron emission tomography (PET) imaging in the diagnosis of free radical‐associated disorders. Methods The bromo derivative of 4‐POBN (precursor) is synthesized in 6 steps starting from 3‐bromopyridine, the fluoro derivative of 4‐POBN (reference) obtained in one step. The lipophilicity and hydrophilicity of the compounds were assessed in silico. Radiochemical synthesis of [18F]3‐fluoro‐4‐POBN is carried out with [18F]TBAF in one step at 120°C for 25 min (Figure 1). The compounds were purified by reversed phase‐HPLC (Figure 2 shows a representative chromatogram). Results The bromo and fluoro derivatives of 4‐POBN were obtained with chemical yields of 40% and 20% respectively. The calculated values −0.25 and −0.35 indicated the compounds are hydrophilic in nature. The optimum temperature for the radiofluorination is found to be 120°C. The decay corrected radiochemical yield (RCY) averaged 17%. At higher temperatures (above 170°C) the precursor decomposes into an elimination product, hindering fluorine‐18 incorporation. Conclusion The bromo and fluoro derivatives of 4‐POBN were synthesized and characterized using standard spectroscopic methods. The radiosynthesis of [18F]3‐fluoro‐4‐POBN was achieved in 99%. This novel radiotracer is currently under preclinical evaluation. R EF E RE N C E S 1. Liou GY, Storz P, Free Radic Res.2010, 44,5. 2. Halliwell B, Gutteridge JMC, In free radicals in Biology and Medicine, 2015,5 Ed, Oxford University Press, Oxford, UK.
Poster Cate gory: Radiochemistry ‐ 18 F P-068 | Using novel radiofluorination methodologies to advance the development and translation of 18F‐labeled PET tracers: The Yale experience Zhengxin Cai1; Songye Li2; Wenjie Zhang3; Nabeel Nabulsi4; Yiyun Huang1 1
PET Center, Department of Radiology and Biomedical Imaging, Yale
University School of Medicine, United States; 2 Yale PET Center,
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Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States; 3 Department of Nuclear Medicine, West China Hospital, Sichuan University, China; 4 Yale PET Center, United States
Objectives Fluorine‐18 labeled radiotracers possess unique advantages for clinical translation. Thus, significant effort and progress have been made in the development of radiofluorination methodologies applicable to the synthesis of PET tracers. The fundamental radiochemistry progress has excited practitioners in the field as it expanded the chemical space for tracer development. However, there still exists a big gap between basic methodology advancement and their applications in the preparation and translation of tracers for use in humans. We have been exploring the recently developed radiofluorination methodologies for the synthesis of tracers for important targets, and have translated to human use stage two tracers targeting KOR and 11b‐HSD1 produced using iodonium ylide precursors and two new tracers targeting SV2A using organotin precursors. Herein, we discuss our efforts in filling the gap between novel radiochemistry methodologies and their applications to the synthesis and translation of radiotracers for clinical studies, including the unique challenges and solutions during each tracer's translation. Methods The tracers under discussion here are all based on promising 11C‐labeled lead tracers that have been validated regarding their binding affinity/selectivity, pharmacokinetics, and metabolism. We designed the 18F‐labeled counterparts and chose the appropriate radiofluorination strategy, including the radiochemistry methodology and the position of radiofluorination. The precursors were synthesized from commercially available materials, and radiolabeled with 18 F‐fluoride. Following guidelines from FDA, we completed quality control tests on chemical purity, radiochemical purity, radionuclide identity, residual organic solvents, metal ion analysis, endotoxin, sterility, etc. Results Radiolabeling of the KOR tracer 18F‐LY2459989 via traditional methodologies yielded rather low radiochemical yields and molar activities (98% radiochemical purity and >99% enantiomeric purity. Conclusions We have successfully synthesized, validated, and translated a number of 18F‐labeled radiotracers to first‐in‐human studies. Among these tracers, 18F‐LY2459989 and 18F‐AS2471907 are produced from iodonium ylide precursors. The synthesis process was scaled up and proven to be robust for routine production of the tracers for human studies. 18F‐SDM‐2 and 18F‐SDM‐8 are produced and validated using organotin precursors. We demonstrate that application of these recently developed radiofluorination methodologies in the routine production of 18F‐labeled compounds greatly expand the scope of available radiotracers for clinical research.
P-069 | Arabinofuranose‐derived PET radiotracers for sensing gram‐negative bacteria in vivo Mausam Kalita; Megan Stewart; Justin Luu; Joseph Blecha; Henry VanBrocklin; Michael Evans; Michael Ohliger; Oren Rosenberg; David Wilson University of California, San Francisco, United States
Objective The motivation behind this project is to develop bacteria‐ specific PET probes targeting the arabinose metabolic pathway in gram‐negative bacteria. Background Gram‐negative bacteria utilize L‐arabinose to produce D‐xylulose‐5‐phosphate, which enters the pentose phosphate pathway.1 Previously, Ordonez et. al. reported gram‐ negative specific uptake of 14C labeled L‐arabinose.2 We hypothesized that different structural isomers of 18F labeled arabinose will incorporate differentially in gram‐negative bacteria. Furthermore, these probes can potentially be used as PET probes both to distinguish an acute bacterial infection from radiologic mimics and to discriminate between gram‐positive and gram‐negative organisms. In this work, we have labeled L‐arabinofuranose with 18F at the 2nd and 5th positions to test this hypothesis.3,4 Additionally, we introduced 18F at the 5th position of D‐arabinofuranose to compare between the L‐ and D‐isomers. Methods As described in Figure 1A, 5‐18F‐L‐Ara, 5‐18F‐D‐Ara, and 5‐18F‐L‐Ara were synthesized from their corresponding peracetylated, tosyl, or triflate precursors analogous to the procedure used for 18F‐FDG. The identity and high radiochemical purity of all 18F sugars were established via TLC. The radiotracers were incubated with small‐ volume E. coli and S. aureus cultures in the exponential phase as previously described, with incorporated radioactivity determined via a Hidex gamma counter.5 Results 2‐18F‐L‐Arabinofuranose avidly and selectively incorporates into E. coli (gram‐negative), but not S. aureus
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(gram‐negative) within an hour. Installing 18F at the 5th position of either D‐ or L‐arabinofuranose resulted in no bacterial uptake. Conclusions 2‐18F‐L‐Arabinofuranose and its derivatives can potentially be used as PET probes to diagnose gram‐negative bacterial infections. Our results also suggest that an intact 5‐OH group in arabinofuranose is crucial for its bioconversion and/or retention in microorganisms. R EF E RE N C E S 1. Nevoigt, E. Progress in Metabolic Engineering of Saccharomyces cerevisiae, Microbiol. Mol. Biol. Rev. 2008, 72(3), 379‐412 2. Ordonez, A. A.; Weinstein, E. A.; Bambarger, L. E.; Saini, V.; Chang, Y. S.; DeMarco, V. P.; Klunk, M. H.; Urbanowski, M. E.; Moulton, K. L.; Murawski, A. M.; Pokkali, S.; Kalinda, A. S.; Jain, S. K. A systemic approach for developing bacteria‐specific imaging tracers, The Journal of Nuclear Medicine, 2017, 58(1), 144‐150 3. Smellie, I. A.; Bhakta, S.; Sim, E.; Fairbanks, A. J. Synthesis of putative chain terminators of mycobacterial arabinan biosynthesis, Org. Biomol. Chem. 2007, 5, 2257‐2266 4. Clark, P. M.; Flores, G.; Evdokimov, N. M.; McCracken, M. N.; Chai, T.; Nair‐Gill, E.; O’Mahnony, F.; Beaven, S. W.; Faull, K. F.; Phelps, M. E.; Jung, M. E.; Witte, O. N. Positron emission tomography probe demonstrates a striking concentration of ribose salvage in the liver, Proc. Nat. Acad. Sci. 2014, E2866‐E2874 5. Mutch, C. A.; Ordonez, A. A.; Qin, H.; Parker, M.; Bambarger, L. E.; Villanueva‐Meyer, J. E.; Blecha, J.; Carroll, V.; Taglang, C.; Flavell, R.; Sriram, R.; VanBrocklin, H.; Rosenberg, O.; Ohliger, M. A.; Jain, S. K.;* Neumann, K. D.;* Wilson, D. M.* [11C]Para‐aminobenzoic acid: a positron emission tomography tracer targeting bacteria‐ specific metabolism, ACS Infect. Dis. 2018; 4(7): 1067‐1072.
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P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-070 | Preclinical evaluation of [18F] Tetrafluoroborate ([18F] TFB) radiopharmaceutical, using a semi automatically method. Juan C. Manrique‐Arias1; Victoria Rodriguez2; Fracisco Garcia; Dafne Garduño 1
Universidad Nacional Autónoma de México (UNAM), Mexico; 2 UNAM,
Mexico
Objectives 18 F‐Tetrafluoroborate (18F‐TFB) is a radiotracer, promising iodide analog for PET imaging of thyroid cancer and sodium/iodide symporter (NIS) reporter activity in viral therapy applications. The aim of this study was to evaluate the safety, pharmacokinetics, biodistribution 18 F‐TFB in healthy rats. Methods [18F‐TFB] was produced using a simple method with [18F]‐ Fluoride, [18F‐TFB] after synthesis was purified with a disposable silver ion‐loaded cation exchange cartridge and three alumina N cartridge, and the quality control was performed by thin‐layer chromatography. The fraction was recovered with 0.9% NaCl and sterile Millex‐GS 0.22 μm filter unit for final injection. After intravenous administration of [18F‐TFB] (31.66 ± 8.6 MBq), static scans were acquired at different times 0.25, 0.5, 1, 2, and 4 h p.i., and tissues of interest (blood, thyroid, heart, lungs, liver,
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spleen, blander, kidneys, small intestine, large intestine, pancreas, urine, and bone) were removed immediately and weighed. Total blood volume and bone mass were estimated as 5.4% and 40% of the total body weight, respectively. Activity in the different tissues was measured using a NaI (Tl) scintillation detector (ORTEC 905‐1, AMETEK, USA). All the data were corrected for physical decay and to calculate uptake in each tissue sample as a fraction of the injected dose, aliquots of the injected dose were counted simultaneously. The results are expressed as a percentage of injected dose per gram of tissue (%ID/g). Results Serial microPET images at 0.25, 0.5, 1, 2, and 4 h post‐ injection (Figure 1A to C) revealed a rapid clearance from blood and high uptake in thyroid, bladder, and stomach, which was consistent with biodistribution data. The distribution of [18F‐TFB] in whole organs, given as percent of the injected dose, at various times after injection, is shown in Figure 1G. Note the rapid blood clearance, reaching less than 4% of injected dose after 0.5 hours. At 1 h p.i., the rat bladder and stomach showed the highest uptake (7.17 ± 0.79 and 4.38 ± 0.018% ID/g, respectively), followed by thyroid, liver, blood, large intestine, kidneys, lungs, and, heart (1.85 ± 0.028, 0.85 ± 0.01, 0.585 ± 0.008, 0.548 ± 0.01, 0.48 ± 0.05, 0.371 ± 0.04, 0.303 ± 0.005 %ID/g, respectively). Conclusions Based in the biodistribution results, which are in agreement with the serial microPET images, we suggest that the critical organs for rat are bladder and stomach. ACKNOWLEDGMENTS This Research was supported by Unidad Radiofarmacia‐ Ciclotrón and Instituto Nacional de Cancerología, México.
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RE FER EN CES 1. Jadvar, et al 2015, Semin Nucl. Med. 2015 January; 45(1). 2. Jiang et al. EJNMMI Research (2017) 7:90. 3. Maite et al. Eur J Nucl Med Mol Imaging (2010) 37:2108‐2116
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-071 | Automated production of high specific activity [18F]6F‐l‐DOPA using a TRACERLab FXFN synthesis module Andrew Mossine1; Sean Tanzey1; Allen Brooks1; Bradford Henderson1; Marc Skaddan2; Melanie Sanford1; Peter Scott3 1
University of Michigan, United States; 2 AbbVie, United States; 3 The
University of Michigan, United States
Objectives 6‐[18F]fluoro‐3,4‐dihydroxyphenylalanine ([18F]6F‐l‐ DOPA) is a PET radiotracer used for imaging of large amino acid transport (oncology) and dopaminergic neurons in the CNS (neurodegeneration, dementia). Synthesis of [18F]6F‐l‐DOPA from nucleophilic [18F]fluoride is desirable due to widespread availability of [18F]fluoride as well as less strenuous equipment demands than electrophilic fluoride. Herein, we describe 2 variations of a method for [18F]6F‐l‐DOPA production that utilizes a commercially‐available pinacolboronate (Bpin) precursor
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that has been fully automated on a one‐reactor GE TRACERlab FXFN synthesis module. Methods Bpin DOPA precursor was purchased from ABX. Production of [18F]6F‐l‐DOPA was fully automated and conducted using a GE TRACERlab FXFN synthesis module. [18F]Fluoride was produced in a GE PETTrace cyclotron, trapped on a Waters QMA Light cartridge preconditioned with bicarbonate, and eluted into the reactor with 500 μL aq. 15 mg/mL TBAOTf + 0.2 mg/mL Cs2CO3. MeCN (1 mL) was added, and the solution was azeotropically dried (100°C w/vac.), then cooled to 50°C. The reactant mixture (4 μmol precursor, 20 μmol Cu (OTf)2, 500 μmol pyridine, 1 mL DMF) was added to the reactor and stirred for 5 min at 50°C then for 20 min at 110°C. A deprotectant/antioxidant (7250 μmol HCl, 50 μmol ascorbic acid, 0.8 mL water) was added to the mixture and stirred for 10 min at 110°C. MeCN (2‐3 mL) was added to the reactor and the mixture was loaded onto a Phenomenex Luna NH25 micron 10 × 250 mm HPLC column. [Alternatively, the crude reactant mixture could be diluted with 10 mL of water containing 1000 μmol ascorbic acid and 100 μmol EDTA and, after dilution, the mixture passed through an HLB Short Plus cartridge (pre‐conditioned with 10 mL ethanol and 10 mL HPLC grade water), with the eluent going to waste. The trapped intermediate was then eluted back into the reactor with 2 mL ethanol from the intermediate vial before loading onto the HPLC column]. In each case, HPLC purification was conducted at 5 mL/min with 1) 90% MeCN 10 mM KOAc pH: 7.5, 10‐13 min; 2) 75% MeCN 10 mM KOAc pH 5.25; 9‐ 20 min. The product peak was collected and diluted with MeCN (100 mL), then passed through a Strata NH2200 mg SPE cartridge. The SPE cartridge was rinsed with 2‐ 3 mL ethanol, then [18F]6F‐l‐DOPA was eluted from the cartridge with 0.9% saline (USP, 10 mL), passed through a Millex GV sterile filter and into a sterile 10 mL dose vial. Total activity of the dose was determined using a Capintec Dose calibrator. Quality control testing was completed including HPLC analysis (Phenomenex Luna NH2 analytical column for identity determination and Phenomenex
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Chirobiotic T and/or CrownPak columns for determination of enantiopurity) and TBA+analysis. Results Fluoride processing and radiolabeling conditions were optimized together and produced protected [18F]6F‐l‐ DOPA in 38 ± 4% non‐isolated TLC radiochemical yield. Near quantitative [18F]6F‐l‐DOPA deprotection was accomplished with conc. HCl and ascorbic acid (as antioxidant). A Luna NH2column enabled purification of [18F]6F‐l‐DOPA from 6‐H and 6‐OH‐DOPA but required a dual‐eluent system (90% MeCN, then 75% MeCN) in order to reduce ascorbic acid contamination of the dose. Trapping/washing/release of [18F]6F‐l‐DOPA were achieved using a Strata NH2 (200 mg) HILIC cartridge in >70% efficiency. Final dose activity was satisfactorily high (6.0‐8.5 % RCY, corresponding to >100 mCi from 1.8 Ci of [18F]fluoride), >99% enantiomeric excess, and passed all requisite quality control release criteria required by USP. Conclusions This method, particularly the back‐end purification and reformulation steps, are superior to existing methods of preparing [18F]6F‐l‐DOPA from [18F]fluoride using a non‐cassette based automated synthesis module as this method only requires a single reactor for both synthesis and deprotection efforts, produces over 5% RCY injectable dose (in 0.9% saline) and passes all quality control tests required by USP. Moreover, it is efficient with respect to mols of precursor thereby reducing overall cost and is automatable using standard one‐reactor synthesis modules.
P os t er C at egor y: Rad i och em i s t ry ‐ 18 F P-072 | Improved synthesis and quality control of [18F]PSMA‐1007 Antje Fasel; Renâ Martin; Diana Baumgart; Sebastian Weidlich; Marco Mueller ABX Advanced Biochemical Compounds, Germany
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Introduction From its first description in 2016,1 [18F]PSMA‐1007 has become a promising radiotracer for prostate cancer imaging. Its fast blood clearance and its alternate route of excretion that bypasses the urinary tract make it an ideal candidate for the diagnostic efficacy in patients with low PSA values and in patients with biochemical recurrence after radical prostatectomy.2 Since its first publication describing the synthesis and quality control of [18F] PSMA‐1007,3 we have further developed the synthesis in order to improve the product quality and product stability. Methods The [18F]PSMA‐1007 one‐step synthesis with cartridge purification has been developed on 10 different radiotracer modules (GE TRACERlab FX FN and MX, FASTlab platform, NEPTIS plug/perform and mosaic RS, IBA SYNTHERA+/V2, Trasis AIO, Scintomics, Eckert & Ziegler modular lab, Sumitomo F‐300). A few changes have been introduced to the previously published method: The counter ion of the precursor molecule was exchanged from trifluoroacetate to acetate. The labelling temperature has been raised to 105°C for most radiotracer synthesizers. Further, the final product is eluted with 5 ml 30% ethanol solution and formulated in 15 ml phosphate buffered saline (PBS) containing 400 mg sodium ascorbate. Quality control procedures have been modified to methods that can be validated in order to obtain accurate and reliable results. Results After a total synthesis time of 44 ± 2 min the synthesis is giving 45 ± 15% radiochemical yield (not decay corrected), depending on the synthesizer module. The product is formulated in 20 ml final product solution. This solution has a shelf life of minimum 10 hours. The pH value was raised to 7.5 by using PBS buffer. Radiochemical (HPLC, TLC) and chemical (HPLC, GC, TBA spot test) purities are within current Pharm. Eur. specifications. The HPLC method was changed to a buffer based method using an
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Ascentis Express ES‐C18 peptide column. This method provides better resolved and sharp peaks in the radioactivity and UV detectors. Details are given in the table below. Conclusion The above described modifications of the synthesis resulted in better radiochemical yields, improved radiochemical and chemical purities and a better product stability. Changes in quality control methods, especially the newly established HPLC method, provides more accurate and reliable quality control results. RE FER EN CES 1. Giesel et al., Eur J Nucl Med Mol Imaging. 2016, 43(10):1929‐30. 2. Giesel et al., J Nucl Med. 2018 Jul 24. pii: jnumed.118.212233. 3. Cardinale et al., Pharmaceuticals (Basel). 2017, 10(4), pii: E77.
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-073 | Two‐step 18F‐labeling of Pept‐ins™ targeting S. aureus via [18F]F‐py‐TFP Kaat Luyten1; Térence Thibangu; Frederik Cleeren2; Ladan Khodaparast; Laleh Khodaparast; Frederic Rousseau3; Joost Schymkowitz3; Guy Bormans4 1
Radiopharmaceutical Research, Department of Pharmaceutical and
Pharmacological Sciences, Katholieke Universiteit Leuven, Belgium; 2
Radiopharmaceutical Research, Department of Pharmacy and
Pharmacology, University of Leuven, Belgium; 3 VIB Switch Laboratory, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, Leuven, Belgium; 4 Katholieke Universiteit Leuven, Belgium
Background The Pept‐In technology is based on a highly selective aggregation of a target protein induced by short peptides, called Pept‐Ins. Pept‐In sequences consist of 7‐20 amino acids and are derived from aggregation prone regions
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(APRs) present in the target protein.1 The specificity of the interaction is mediated by the formation of intermolecular beta‐sheet structures. Brednarska et al.2 showed that the sequence specificity of beta‐sheet aggregation can be exploited to target redundant aggregation‐ prone regions in the S. aureus proteome by the C30 amyloidogenic peptide, thereby inducing proteostatic collapse leading to bacterial cell death. The observed
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specificity of the amyloid toxicity indicates the large potential of radiolabeled C30 Pept‐In for in vivo visualization of S. aureus infection with PET. Methods C30 was modified for 18F‐labeling by synthesis of NH2‐PEG2‐CO‐NH‐C30. To evaluate conservation of functionality of modified C30, Minimal Inhibitory Concentration (MIC) of NH2‐PEG2‐CO‐NH‐C30 and
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F‐py‐CO‐NH‐PEG2‐CO‐NH‐C30 were determined on S. aureus. First, 6‐[18F]fluoronicotinic acid 2,3,5,6‐ tetrafluorophenyl ester ([18F]F‐py‐TFP) was synthesized in a fully automated synthesis module (AllinOne, Trasis) starting from the trimethylammonium precursor.3 [18F]F‐ py‐TFP was purified by reversed‐phase HPLC (Xbridge™ 5 μm 4.6 × 150 mm, ethanol/milliQ water 50:50 (V/V)) prior to conjugation to NH2‐PEG2‐CO‐NH‐C30, under mild conditions (sodium hydrogen carbonate 0.05 M, pH 8.5, room temperature, 15 min). A Dionex Ultimate 3000 LC System (Acquity UPLC BEH C18 1.7 μm 2.1 mm × 50 mm column [Waters, USA]) coupled in series to a 3 inch NaI (Tl) radioactivity detector and an ultra‐high resolution time‐of‐flight mass spectrometer with electron spray ionization (ESI) (Brukers maXis impact) was used for analysis of the reaction mixture. The mobile phase consisted of a gradient of 0.1% formic acid in milliQ water and acetonitrile at a flow rate of 0.6 mL/min with a column temperature of 40°C. For deconvolution analysis of the raw mass spectral data the software program DataAnalysis (Bruker Daltonik, Bremen, Germany) was used. Results MIC values of C30, NH2‐PEG2‐CO‐NH‐C30 and 19F‐py‐ CO‐NH‐PEG2‐CO‐NH‐C30 on S. aureus were similar. The identity of the observed peaks in the radiochromatogram were confirmed against reference 19F‐py‐CO‐NH‐ PEG2‐CO‐NH‐C30 and 19F‐py‐TFP observed in the UV channel (215 nm and 254 nm, respectively). The molecular ion mass of the NH2‐PEG2‐CO‐NH‐C30 (Rt = 8.3 min on HPLC) and 19F‐py‐CO‐NH‐PEG2‐CO‐NH‐C30 (Rt = 9.1 min on HPLC) corresponded to the respective theoretical values. [18F]F‐py‐CO‐NH‐PEG2‐CO‐NH‐C30 (Rt = 9.3 min on HPLC) was formed rapidly (15 min) in a 7% yield relative to [18F]F‐py‐TFP starting activity. Figure 1. A: LC‐UV215 nm chromatogram of 19F‐py‐CO‐ NH‐PEG2‐CO‐NH‐C30. B: LC‐UV254 nm chromatogram of 19F‐py‐TFP C: LC‐UV254 nm chromatogram of 19F‐py‐ COOH D: Radio‐chromatogram of the reaction mixture which contains 1:[18F]F‐py‐COOH (77 %) 2: [18F]F‐ py‐ CO‐NH‐PEG2‐CO‐NH‐C30 (7 %) 3: [18F]F‐py‐TFP (16 %). Conclusion Derivatisation for radiolabeling did not affect the biological activity of 19F‐py‐CO‐NH‐PEG2‐CO‐NH‐C30. A successful two‐step radiolabeling method was developed. Full automation of the radiolabeling procedure including HPLC purification is being implemented and biological evaluation [18F]F‐py‐CO‐NH‐PEG2‐CO‐NH‐C30 in a mouse model of local S. aureus infection will be presented. 19
R EF E RE N C E S 1. Gallardo R et al. [2016], Science, 354, 6313. 2. Bednarska N et al. [2016], Molecular Microbiology 99 (5), 849‐865.
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3. Olberg DE et al. [2010], Journal of Medicinal Chemistry 53 (4), 1732‐1740.
P os t er C at egor y: Rad i oc h em i s t ry ‐ 18 F P-074 | An open‐label, single arm trial to explore potential imaging biomarkers correlate with efficacy of bevacizumab combined with conventional therapy in newly diagnosed glioblastoma Li Li; Shuang Yuan; Jin Yu; Ning Liu; Hui Zhang; Rong Tao; Zheng Fu; Shu Zhao; Liang Xu; Yuhui Liu; Yongsheng Gao Shandong Cancer Hospital and Institute, China
Purpose To investigate the ability of potential imaging biomarkers to predict the response of bevacizumab (known as Avastin) combined with conventional therapy in newly diagnosed glioblastoma. Materials and methods Patients newly diagnosed with glioblastoma after surgery were enrolled to receive Avastin plus conventional concurrent radiotherapy and temozolomide. 18F‐AlF‐ NOTA‐PRGD2 positron emission tomography/computed tomography (18F‐RGD PET/CT) and dynamic contrast‐ enhanced magnetic resonance imaging (DCE‐MRI) were performed at baseline, week 3, and week 10 for each patient. Molecular information was assessed in patients' tumor tissue. Statistical methods included the KaplanMeier method as well as univariate and multivariate Cox proportional hazard models. This trial was registered with Clinicaltrials.gov, number NCT01939574, ID ML28676. Results Twenty patients were prospectively enrolled, and the median follow‐up time was 16 months (range, 4‐ 42 months). The median progression‐free survival (PFS) was 9.66 months (95% confidence interval [CI], 6.20‐ 13.12 months). Parameters on 18F‐RGD PET/CT and DCE MRI at baseline and changes from baseline to week 10 were found not to be predictive of PFS. However, a greater decrease in the mean standard uptake value (SUVmean) from week 3 to week 10 was associated with better PFS (12.3 vs 7.5 months, log rank P = 0.009). In addition, low expression levels of epidermal growth factor receptor and vascular endothelial growth factor (VEGFA) were significantly associated with a longer PFS (7.46 vs 11.40 months, P = 0.045; high vs low, 8.02 vs 11.40 months, P = 0.028). Isocitrate dehydrogenase 1 appeared to prolong PFS, but the association was not statistically significant (mutation vs non‐mutation, 4.2 vs 10.8 months, P = 0.065). Multivariate Cox hazard models were derived
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for PFS initially using clinical factors such as age, gender, smoking history, Karnofsky performance status, and parameters for which P < 0.1. A greater decrease in SUVmean before and after Avastin treatment remained a signficant predictor of better PFS independent of VEGFA expression (95% CI, 1.82‐11575.72, P = 0.026). Conclusion 18 F‐RGD PET/CT may be valuable in assessing the response of glioblastoma to treatment with the combination of Avastin and CCRT, with a greater decrease in SUVmean predicting better PFS.
Poster Cate gory: Radiochemistry ‐ 18 F P-075 | High‐purity synthesis of [18F]‐AlF‐ pHLIP using semi‐preparative HPLC
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approved for a PET imaging study of breast cancer at our site and is currently undergoing clinical translation. Existing [18F]‐AlF‐pHLIP literature methods comprise the synthesis of [18F]‐AlF3 from AlCl3 in aqueous 18F‐, subsequent radiolabeling of NOTA‐pHLIP, and rapid formulation by solid‐phase extraction on a C18 cartridge. These methods have afforded [18F]‐AlF‐pHLIP in 4–50% yield in >90% radiochemical purity in support of PET imaging studies in mice. However, to satisfy more rigorous quality control standards for human studies, we sought to improve the radiochemical purity by implementing preparative HPLC (prep‐HPLC) purification of the radiolabeled peptide before formulating it. Herein, we describe a [18F]‐ AlF‐pHLIP synthesis that incorporates prep‐HPLC purification, resulting in 100% radiochemical purity. Methods F was trapped on a QMA anion‐exchange cartridge (Waters), rinsed with 10 mL metal‐free water, and dried over nitrogen gas. The isotope was eluted with 0.2 mL of KHCO3 (0.2 M) into a reaction vial precharged with 20 μL of metal‐free water and 5 μL of glacial acetic acid. An AlCl3 solution was prepared by dissolving 7 mg of AlCl3 in 0.1 M ammonium acetate in metal‐free water (pH 4.1). 20 μL of the AlCl3 solution was added to the reaction vial and the mixture was stirred at room temperature for 10 min to form [18F]‐AlF3. NOTA‐pHLIP was dissolved in 0.1 mL of DMSO and added to the reaction vial, followed by 0.1 mL of acetonitrile. The mixture was heated 100°C for 10 min, allowed to cool for 1 min, and diluted with 1 mL of acetonitrile and 2 mL of water. This crude product mixture was loaded onto a C6‐phenyl column (250 × 10 mm, 5 μm, Phenomenex) and purified over 30 min with a solvent gradient of 25‐80% acetonitrile in water with 0.1% 18 ‐
Stephen Carlin1; Eva Burnazi2; Serge Lyashchenko2; Jason Lewis1 1
Memorial Sloan Kettering Cancer Center, United States; 2 MSKCC,
United States
Objective pH (low) insertion peptides (pHLIP peptides) have emerged as novel pH‐dependent delivery vehicles for inserting molecular probes through acidic cancer cell membranes with high specificity. In particular, pHLIP can be labeled with radiometals for PET imaging studies with chelating ligands conjugated to the peptide. Use of the NOTA (1,4,7‐triazacyclononane‐N′,N″,N‴‐triacetic acid) chelator has recently expanded this methodology to include 18F, which can be radiofluorinated via [18F]‐AlF3. One variant of NOTA‐derivatized pHLIP (Var3) has been
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trifluoroacetic acid at 5 mL/min and 220 nm. The product was collected at 13‐14 min into 40 mL of sterile water and loaded onto a C18 Light cartridge (Waters). The cartridge was rinsed with 10 mL of sterile water, and the product was eluted and filtered into the final product vial with 1 mL of ethanol and 9 mL of phosphate‐buffered saline. An aliquot of the final product was taken to assay its radiochemical purity by analytical HPLC on a biphenyl column (150 × 4.6 mm, 2.6 μm, Phenomenex) with a solvent gradient of 60‐80% acetonitrile in water with 0.1% trifluoroacetic acid at 1 mL/min and 220 nm (Figure 2). Results The decay‐corrected RCY was 5‐10% (n = 10) and the radiochemical purity was 100% (n = 10) as determined by analytical HPLC, improving upon previous methods to provide [18F]‐AlF‐pHLIP in higher and more consistent purity suitable for human use. R EF E RE N C E S Demoin DW, et al., Bioconjug Chem. 2016 Sep 21;27(9):2014‐23. Wyatt LC, et al., Trends Biotechnol. 2017 Jul;35(7):653‐664.
Poster Cate gory: Radiochemistry ‐ 18 F P-076 | 18F‐ PEG2‐OTSSP167 inhibits maternal embryo leucine zipper kinase for PET imaging of triple‐negative breast cancer Hu Jia1,2; Fan Hu1,2
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Memorial Sloan Kettering Cancer Center, United States; 2 MSKCC,
United States
Objectives Breast cancer seriously endangers the health of middle‐aged and elderly women. At present, the diagnosis and treatment of non‐triple‐negative breast cancer patients are maturing, but there is no effective diagnosis and treatment for patients with triple negative breast cancer (TNBC). A large number of literatures confirm that MELK (maternal embryo leucine zipper kinase) is highly expressed in TNBC. Based on this, OTSSP167 (a small molecule compound MELK) was significantly inhibited. A new diagnostic TNBC targeted imaging 18F‐PEG2‐OTSSP167, which is a small molecule, is easy to prepare and can be used to dynamically monitor the changes of TNBC patients in real time. Methods Breast cancer cell lines, MDA‐MB‐231‐UR and MCF‐7, were used as MELK overexpression and underexpression models, respectively. OTSSP167 was labeled with 18F using polyethylene glycol (PEG2). MicroPET imaging, biodistribution, and autoradiography studies were performed at the time of 0.5 h, 1 h, 2 h, and 4 h in mice bearing MDA‐MB‐231‐UR and MCF‐7 tumors after injection of 18F‐PEG2‐OTSSP167 to verify the targeting ability of the tracer. Results The labeling rate of 18F‐PEG2‐OTSSP167 was 91.00 ± 2.04% (n = 5), and the radiochemical purity after
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purification was 95.80 ± 1.75% (n = 5). Micro PET images, biodistribution, and autoradiography studies showed high uptake of the tracer in MDA‐MB‐231‐UR tumors. OTSSP167 caused dose and time dependent growth inhibition and apoptosis in melanoma cells in vitro and suppressed MDA‐MB‐231‐UR tumor growth in vivo. Conclusions OTSSP167, an MELK inhibitor, inhibits tumor growth and MELK expression. 18F‐PEG2‐OTSSP167, an easily‐ prepared probe, can be used to visualize MELK positive tumors and to monitor the effect of OTSSP167 therapy, suggesting its prospective clinical application. KEYWORDS MELK; OTSSP167; 18F; positron‐emission tomography
Poster Cate gory: Radiochemistry ‐ 18 F
P-077 | Experimental study on the diagnosis of hepatocellular carcinoma by GLU PET/CT
18
F‐NOTA‐NSC‐
Xianhong Xiang The First Affiliated Hospital of Sun Yat‐Sen University
Objectives To investigate the feasibility of 18F‐NOTA‐NSC‐GLU small molecule probe for non‐invasive diagnosis of hepatocellular carcinoma by PET/CT Methods (a) Establish animal models of hepatocellular carcinoma: HCC HepG2 cells(1‐2*10^7) were subcutaneously injected into BALB/C nude mice. At the time of the experiments, the tumor reached 6‐10 mm (diameter), mice were 7‐9 week old. (b) Small‐animal PET/CT imaging: On the first day, we performed 18F‐NOTA‐NSC‐ GLU(4‐6 MBq)PET/CT imaging on nude mice and made continuous dynamic imaging at 15, 30, 60, and 90 min after injection of imaging agent, and delineated the region of interest of the tumor and liver on the image, expressed by the dose rate per gram of tissue injection, and the tumor/liver ratio is calculated. (c) 18F‐FDG PET/CT in vivo imaging: On the second day, mice were scanned with 18F‐FDG (4–6 MBq) at 60 min. The results were compared with the first day imaging results. (d) Pathological examination: After imaging, the nude mice were sacrificed after anesthesia. We dissected and fixed the tumor and normal liver tissues in 4% paraformaldehyde solution to prepare paraffin sections for HE staining and EAACI immunohistochemical staining.
Results (a) 18F‐NOTA‐NSC‐GLU imaging results: After 15 min of injection, the radioactivity was gradually concentrated in the tumor tissue, and the tumor morphology became clear. The development of tumor was best in 30 min, and the morphology was clear; the tumor was still visible at 60 min; the development of tumor was decreased after 90 min. Tumors uptake of 18F‐NOTA‐NSC‐GLU (2.13 ± 0.0659%ID/g) were significantly higher than normal muscle tissue (0.52 ± 0.0312%ID/g). (b) 18F‐FDG imaging results of the same group of tumor‐bearing nude mice: the development of tumor was the best at 60 min, and the tumor uptake of 18F‐FDG was significantly higher than that of normal muscle tissue. Quantitative analysis showed that the tumor tissue 18F‐NOTA‐ NSC‐GLU uptake value was higher than the 18F‐FDG uptake value. The 18F‐NOTA‐NSC‐GLU tumor/muscle ratio (4.04) was significantly higher than the 18F‐FDG tumor/muscle ratio (2.59). (c) Pathological examination showed that a large number of abnormal cancer cells were observed in liver cancer tissues. Immunohistochemical results showed diffuse EAAC1 staining in liver cancer tissues, whereas no EAACI staining was observed in normal liver tissues. Conclusion In summary, 18F‐NOTA‐NSC‐GLU PET/CT can be used for non‐invasive diagnosis of hepatocellular carcinoma, which is of great significance for the early diagnosis or therapeutic evaluation of hepatocellular carcinoma.
P os t er C at egor y: Rad i och em i s t ry ‐ 11 C a nd Ot her P os it r o n Em it ter s P-078 | Development of a novel PET ligand for imaging leucine rich repeat kinase 2 Zhen Chen1; Tuo Shao1; Hualong Fu1; Lu Wang2; Thomas Collier3; Hsiao‐Ying Wey1; Yihan Shao4; Lee Josephson1; Steven Liang1 1
MGH/Harvard, United States; 2 The first affiliated hospital of Jinan
University, China; 3 Advion Inc, United States; 4 University of Oklahoma, United States
Objectives Leucine‐rich repeat kinase 2 (LRRK2) is an important protein that is implicated in the increased risk of familial and sporadic Parkinson's disease (PD). Currently, inhibition of LRRK2 represents one of the prevailing therapeutic strategies for PD. 3‐Methoxy‐4‐((4‐(methylamino)‐5‐ (trifluoromethyl)pyrimidin‐2‐yl)amino)phenyl)(morpholino)methanone (compound A) is a potent and selective
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LRRK2 inhibitor with the IC50 value of 9 nM for phospho‐LRRK2 (pLRRK2).1 Herein, we report an efficient radiosynthesis of 3‐[11C]methoxy‐4‐((4‐(methylamino)‐5‐(trifluoromethyl)pyrimidin‐2‐yl)amino)phenyl) (morpholino)methanone ([11C]compound A) as a novel potential PET ligand for LRRK2 imaging. Methods The synthesis of LRRK2 inhibitor (compound A) and its precursor (3‐hydroxy‐4‐((4‐(methylamino)‐5‐ (trifluoromethyl)pyrimidin‐2‐yl)amino)phenyl) (morpholino)methanone (desmethyl‐compound A) were carried out in a convergent fashion. Briefly, the key intermediate (4‐amino‐3‐methoxyphenyl)(morpholino) methanone (3) was constructed in 86% yield over three steps via condensation between benzoic acid (1) and morpholine followed by iron powder‐mediated reduction of nitrobenzene 2. Nucleophilic substitution of 2,4‐ dichloro‐5‐(trifluoromethyl)pyrimidine 4 with methylamine led to the isolation of 5 in 40% yield, which was then condensed with 3 to give the desired LRRK2 inhibitor A in 31% yield. Demethylation of compound A readily proceeded to give the corresponding precursor desmethyl‐compound A in 69% yield upon treatment with boron tribromide. The radiosynthesis was carried out by heating a solution of desmethyl‐compound A (1.5 mg), [11C]CH3I, NaOH (1 M, 4 μL) in DMF (0.3 mL) at 80°C for 5 min. We also measured the lipophilicity of [11C]compound A using liquid‐liquid partition between n‐octanol and PBS (“shake flask method”) to predict its blood‐brain barrier permeability, and stability in three different formulations for injection. Results The standard compound A and its precursor desmethyl‐ compound A were obtained in 27% overall yield over three steps and 18% overall yield over four steps, respectively.
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The desired PET ligand [11C]compound A was achieved in 19% isolated radiochemical yield (relative to [11C]CH3I, non‐decay corrected). The radiochemical purity of the tracer was greater than 99%, and the molar activity was higher than 37 GBq/μmol at end of synthesis (EOS). No signs of radiolysis was observed for [11C]compound A up to 90 min after formulation with PBS, 10% EtOH/saline or saline containing 0.8% ascorbic acid, 0.7% Tween 80 and 2.7% ethanol. The logD value of [11C]compound A was determined to be 2.93 ± 0.02 (n = 3), which indicated a high possibility of brain penetration. Conclusion We have described a facile synthetic route to compound A, desmethyl‐compound A, and [11C]compound A, which may facilitate future development and evaluation of LRRK2 PET tracers. ACKNOWLEDGMENTS We thank Drs. Thomas Brady, Neil Vasdev, and Elijahu Livni (Nuclear Medicine, MGH) for their helpful discussion. RE FER EN CE 1. Estrada et al., J. Med. Chem. 2012, 55, 9416‐9433.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-079 | Base effect on the radiosynthesis of P2X7R radioligands [11C]GSK1482160 and its halo‐analogs Mingzhang Gao; Min Wang; Jill Meyer; Jonathan Peters; Paul Territo; Hamideh Zarrinmayeh; Qi‐Huang Zheng Indiana University School of Medicine, United States
Objectives P2X7 receptor (P2X7R) is an adenosine triphosphate (ATP)‐gated ion‐channel, which is found in the immune, peripheral, and central nervous systems, implicated in ATP‐mediated cell death, regulation of receptor trafficking and inflammation, and associated with various inflammatory, immune, neurologic, and musculoskeletal disorders. GSK1482160 ((S)‐N‐(2‐chloro‐3‐(trifluoromethyl)benzyl)‐ 1‐methyl‐5‐oxopyrrolidine‐2‐carboxamide) developed by GlaxoSmithKline is a potent P2X7R antagonist with excellent biological activity (IC50 3 nM for human P2X7R).1 P2X7R is an attractive therapeutic target as well as imaging target for biomedical imaging technique positron emission tomography (PET). We have previously developed and ((S)‐N‐(2‐chloro‐3‐ characterized [11C]GSK1482160
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(trifluoromethyl)benzyl)‐1‐[11C]methyl‐5‐oxopyrrolidine‐ 2‐carboxamide) as a P2X7R radioligand for neuroinflammation,2,3 clinical evaluation of [11C]GSK1482160 in healthy controls and patients is currently underway, and the estimation of radiation dosimetry for [11C] GSK1482160 in normal human subjects has been reported.4 This ongoing study is to develop [11C]halo‐ GSK1482160 analogs (F‐, Br‐, and I‐) as new P2X7R radioligands. During the radiotracer production of [11C] GSK1482160 and its halo‐analogs [11C]‐methylated at cyclic amide position, there was always a radiolabeled isomer by‐product [11C]‐methylated at side chain amide position formed. Here we investigate the base effect on the radiosynthesis of [11C]GSK1482160 and its halo‐analogs. Methods The reference standards halo‐GSK1482160 (F‐, Br‐, and I‐) were synthesized from L‐pyroglutamic acid or methyl L‐ pyroglutamate with 2‐halo‐3‐(trifluoromethyl)benzylamine (F‐, Br‐, and I‐) in three steps. Their corresponding precursors desmethyl‐halo‐GSK1482160 (F‐, Br‐, and I‐) were synthesized from L‐pyroglutamic acid with 2‐halo‐3‐(trifluoromethyl)benzylamine (F‐, Br‐, and I‐) in one step. The precursor contains both cyclic amide and side chain amide that can be [11C]‐methylated. N‐[11C]methylation under basic condition of desmethyl‐halo‐GSK1482160 (F‐, Br‐, and I‐) with [11C]CH3OTf at cyclic amide and side chain amide would form [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐GSK1482160 isomer (F‐, Br‐, and I‐), respectively, and the ratio of the radiolabeled products [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐ GSK1482160 isomer (F‐, Br‐, and I‐) was changed by different solid base. Results The chemical yields for halo‐GSK1482160 (F‐, Br‐, and I‐) and desmethyl‐halo‐GSK1482160 (F‐, Br‐, and I‐) were moderate to high. The radiochemical yields for [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐ GSK1482160 isomer (F‐, Br‐, and I‐) can be maximized to 40‐50% based on [11C]CO2 and decay‐corrected to
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end of bombardment (EOB). The radiochemical purity was >99%, and molar activity at EOB was 370‐1110 GBq/μmol. If NaOH‐Na2CO3 (w/w 1:2, solid) was used as a base, [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐GSK1482160 isomer (F‐, Br‐, and I‐) were formed in a ~10:1 ratio. If NaOH (solid) was used as a base, [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐GSK1482160 isomer (F‐, Br‐, and I‐) were formed in a ~1:1 ratio. If NaH (95% dry or 60% dispersion in mineral oil, powder) was used as a base, [11C] halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐ GSK1482160 isomer (F‐, Br‐, and I‐) were formed in a ~1:10 ratio. Conclusions New P2X7R radioligands [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) have been successfully radiosynthesized. The base effect on the radiotracer production of [11C]GSK1482160 and [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) has been investigated. The different base can adjust the ratio of the radiolabeled products [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) and [11C]halo‐GSK1482160 isomer (F‐, Br‐, and I‐) during the radiosynthesis. Therefore, the expected labeled products [11C]halo‐GSK1482160 (F‐, Br‐, and I‐) can be maximized and the unexpected labeled products [11C] halo‐GSK1482160 isomer (F‐, Br‐, and I‐) can be minimized by the use of the appropriate solid base in radiosynthesis. ACKNOWLEDGEMENTS This work was partially supported by Indiana University Showalter Young Investigator Award and Indiana University Department of Radiology and Imaging Sciences in the United States.
RE FER EN CES 1. Z. Ali, et al. Br. J. Clin. Pharmacol. 2013, 75, 197‐207. 2. M. Gao, et al. Bioorg. Med. Chem. Lett. 2015, 25, 1965‐1970. 3. P.R. Territo, et al. J. Nucl. Med. 2017, 58, 458‐465. 4. M.A. Green, et al. J. Nucl. Med. 2018, 59(S1), 1009.
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Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-080 | Preclinical evaluation of [11C] AZ13713945 and its analogs as muscarinic acetylcholine receptor M4 PET ligands Xiaoyun Deng1; Akiko Hatori2; Tuo Shao1; Katsushi Kumata2; Zhen Chen1; Yihan Shao3; Shaofa Sun4; Lee Josephson1; Ming‐Rong Zhang2; Steven Liang1 1
MGH/Harvard, United States; 2 Department of Radiopharmaceutics
Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3
University of Oklahoma, United States; 4 College of Nuclear Technology &
Chemistry and Biology, Hubei University of Science and Technology, China
Objectives VU0467485 was identified as the first potent M4 PAM to overcome major species differences in potency while maintaining high selectivity versus M2 (rat, dog, cyno,
and human EC50 values > 30 μM), CNS penetration, and in vivo efficacy.1 The goal of the project was to radiolabel VU0467485 and two other derivatives for subsequent in vitro and in vivo evaluation. Methods The cyclization of biacetyl 1 and 2‐cyanoacetohydrazide 2 led to intermediate 3 in 37% yield. Phosphorus oxychloride was used to chlorinate compound 3 to generate pyridazine chloride 4 in 67% yield. Methyl carboxylate 6 was prepared by cyclization of compound 4 and methyl 2‐ mercaptoacetate 5 in 98% yield. When hydrolyzed by potassium hydroxide, intermediate 6 was converted to corresponding carboxylic acid 7 in 87% yield. Through condensation reactions under HATU and DIPEA, a series of amides 11 and 12 were produced with corresponding amines 8 or 9 and acid 7 in yields of 41‐85%. Amine 8b was generated by reduction of benzonitrile compound with LiAlH4 in yield of 52%. BH3‐THF complex was used to get 8c in 53% yield. By demethylating methoxy compound 9 with hydrobromic acid in reflux condition, we could get ammonium bromide 10 as precursors in 50‐85% yields. The 11C‐labeling was conducted with [11C]CH3I in DMF
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at 80oC for 5 min under basic conditions, followed by semi‐ preparative radioHPLC purification and reformulation in a saline solution (3 mL) containing 100 μL of 25% ascorbic acid in sterile water and 100 μL of 20% Tween 80 in ethanol. Results The synthesis of standards 11 and precursors 12 was achieved in seven steps with overall 14‐18% and 9‐12% yields, respectively. The M4 PAM ligands [11C]11a‐ [11C]11c were synthesized in ca. 10% non‐decay corrected radiochemical yield starting from [11C]CO2 at the end of synthesis (35‐40 min). The ligands were produced in 1.8‐2.3 GBq with high molar activity (>74 GBq/μmol) and without observed radiolysis in 90 min. The in vitro binding specificity of [11C]11a‐[11C]11c was evaluated by in vitro autoradiography on SD rat brain. The distribution of bound radioactivity of all three M4 ligands was heterogeneous with decreasing uptake order in thalamus, striatum, cerebellum, cerebral cortex and hippocampus. In particular, [11C]11c showed ca. 90% reduction during self‐blocking studies. Conclusion We have efficiently prepared three M4 PAMs and their corresponding precursors for 11C‐labeling. The radiosynthesis was performed in excellent radiochemical yield, high radiochemical purity and high molar activity. In vitro autoradiography studies confirmed moderate‐to‐high specific binding of all these M4 PAM ligands. Further evaluation in PET is planned to determine in vivo specificity. R EF E RE N C E S 1. M. R. Wood, M. J. Noetzel, B. J. Melancon, M. S. Poslusney, K. D. Nance, M. A. Hurtado, V. B. Luscombe, R. L. Weiner, A. L. Rodriguez, A. Lamsal, ACS Med. Chem. Lett. 2016, 8, 233.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-081 | Immuno‐PET imaging with 89Zr‐atezolizumab in low and high PD‐L1 expressing renal cell carcinoma patient‐derived xenograft models Guiyang Hao1; Aditi Mulgaonkar1; Layton Woolford1; Kien Nham1; Bing Guan1; James Brugarolas1; Xiankai Sun2 1
UT Southwestern Medical Center, United States; 2 University of Texas
Southwestern Medical Center, United States
Objectives The programmed death‐1 receptor/programmed death– ligand 1 (PD‐1/PD‐L1) axis mediated immune checkpoint cascade is an essential “defense mechanism” promoting tumor progression by evasion of host immune surveillance.
PD‐L1 expression has been found to be correlated with poor prognosis in renal cell carcinoma (RCC) patients. Immunotherapy targeting PD‐L1 could lead to variable outcomes, owing to differences in PD‐L1 expression levels in patients with RCC. Hence, to optimize immunotherapeutic regimens for treating RCC, newer approaches for patient stratification based on PD‐L1 expression need to be introduced. These methods could help to attain the desired and consistent treatment outcomes and also enable detection of high‐risk RCC populations with poor prognosis. Positron emission tomography (PET) imaging of PD‐L1 in RCCs could be an important non‐invasive and sensitive tool to distinguish potential “responding” from “non‐responding” patient populations based on variation in PD‐L1 expression and thereby aid in making treatment decisions. Herein, we report the preparation of zirconium‐89 (89Zr) labeled Atezolizumab (ATZ, an anti‐PD‐L1 monoclonal antibody) for PET imaging assessment of PD‐L1 expression in RCC patient‐derived xenograft (PDX) models. Methods ATZ was conjugated with deferoxamine (DFO) at a molar ratio of 5:1 (DFO:ATZ) and the chelating number of DFO per ATZ was determined by liquid chromatography–mass spectrometry (LC‐MS) analysis. The radiolabeling with 89 Zr followed previously published methods.1,2 In vitro assays were performed to confirm stability and immunoreactivity (Lindmo assay 3) of the immunoconjugate. One patient's tumor cells were identified with high levels of PD‐L1 on immunohistochemistry (>30%), and the resulted PDX model using SCID/NOD mice was confirmed to preserve the same PD‐L1 expression. PET/CT imaging was performed by intravenous injection of ~100 μCi of 89Zr‐DFO‐ATZ, followed by scans up to 7 days post‐injection. Post‐imaging, the mice were sacrificed, and tumors were excised and subject to histological
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analyses to obtain PD‐L1 expression levels. Another PDX model with negligible to low PD‐L1 expression (IHC < 5%) was also included for comparison. Results The LC‐MS analysis showed that the conjugate of DFO‐ ATZ was prepared at the molar ratio of ~1.0 DFO per ATZ. The DFO‐ATZ was labeled with 89Zr at a specific activity within 2‐4 μCi/μg, with ~91.4% radiolabeling efficiency and high (~99%) radiochemical purity. The immunoreactivity of 89Zr‐DFO‐ATZ was 86.2 ± 4% (n = 6) of that of ATZ and its stability was >80% upon incubation with rat serum at 37°C out to 6 days. The average uptake in the high PD‐L1 expressing tumor grafts (n = 6) was 4.7 ± 0.7% injected dose/g (%ID/g) on day 6/7, which is significantly higher than that (3.1 ± 0.5% ID/g; n = 3) in the control (P < 0.01). Of note, the tumorgraft volumes on the day of imaging were not significantly different between the two groups (high PD‐L1 expression line: 831.9 ± 473 mm3 versus low PD‐L1 expression line: 1010.3 ± 492.6 mm3, P = 0.62). Furthermore, the tumor/muscle contrast observed on day 6/7 for the high PD‐L1 expressing tumorgraft group was 4.4 ± 0.4, which is also significantly higher than that (2.7 ± 0.6) for the control group on day 6 (P < 0.05). Conclusions A practical immunoPET method was developed with 89 Zr‐labeled PD‐L1 antibody for noninvasive imaging differentiation of PD‐L1 expression levels in vivo, which is of clinical significance to enable more efficacious immune‐checkpoint inhibitor therapies. ACKNOWLEDGMENTS This work was supported by the Cancer Prevention and Research Institute of Texas (RP110771), the Career Enhancement Program Award from NIH grant P50CA196516, and the Dr. Jack Krohmer Professorship Funds. R EF E RE N C E S 1. Vosjan, M.J.W.D., et al., Nat. Protocols, 2010.5(4): p. 739‐743. 2. Zeglis, B.M. and J.S. Lewis, Journal of Visualized Experiments, 2015(96): p. e52521. 3. Lindmo, T., et al., Journal of immunological methods, 1984.72(1): p. 77‐89.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-082 | An original radio‐biomimetic synthesis of imaging
11
C‐nor‐buprenorphine for PET
Fabien Caillé1; Sylvain Auvity2; Maud Goislard1; Sebastien Goutal2; Nicolas Tournier2; Bertrand Kuhnast1
1
Imagerie Moléculaire In Vivo UMR1023 CEA, INSERM, CNRS,
Université Paris Sud, Université Paris‐Saclay, Service Hospitalier Frédéric Joliot, France; 2 CEA, France
Objectives Buprenorphine (BUP) is an opioid drug used for analgesia and oral substitution for heroin addiction. BUP is metabolized by cytochrome P450 3A4 (CYP3A4) into nor‐buprenorphine (nor‐BUP), a respiratory depressor accounting for the lethal side effects of BUP.1 To date, poorly is known about the mechanism through which nor‐BUP exerts its respiratory effects since in vitro data demonstrated that P‐glycoprotein (P‐gp, ABCB1) limits its brain penetration. The most advance technique to elucidate the neurokinetic of nor‐BUP in vivo is positron emission tomography (PET) imaging using carbon‐11 radiolabeled nor‐BUP. BUP has already been labeled with carbon‐112 but because of the complexity of the related chemistry, no precursor is available for nor‐BUP radiolabeling. Herein, we described an original radio‐ biomimetic (RBM) approach to synthesize 11C‐nor‐BUP by N‐dealkylation of 11C‐BUP using CYP3A4 human microsomes and the very first PET images of 11C‐nor‐ BUP in the rat brain with and without inhibition of the P‐gp transport function. Methods Biotransformation of BUP into nor‐BUP using CYP3A4 was optimized under non‐radioactive conditions, and the conversion rate was determined using HPLC with UV detection. 11C‐BUP was synthesized according to the literature2 and incubated with CYP3A4 under predetermined optimized conditions to afford ready‐to‐ inject 11C‐nor‐BUP after HPLC purification. Radiochemical yields (RCY), radiochemical purity (RCP) ,and molar activity (MA) were assessed by analytical radio‐HPLC. Sprague‐Dawley rats (340 ± 130 g, n = 3) were injected i.v. with 11C‐nor‐BUP (4.97 ± 4.96 MBq) and brain PET images were acquired. PET data are expressed as standardized uptake values (SUV) taking into account animal weight and injected dose. In addition, 11C‐nor‐ BUP PET imaging under P‐gp inhibition conditions using tariquidar (10 mg/kg) are ongoing. Results Up to 32% of conversion of nor‐BUP was obtained under optimized conditions (37°C, 20 min, 1.5 mg/mL of CYP3A4 in the presence of cytochrome b5). Longer reaction time resulted in higher conversion but competed with carbon‐11 half‐life (t1/2 = 20.4 min). Using the RBM approach, 11C‐nor‐BUP was synthesized in 2 ± 1% RCY within 80 minutes with RCP > 98% and 90 ± 15 GBq/μmol MA (n = 7). 11C‐nor‐BUP showed extremely low penetration in the rat brain (SUV0→16.5min = 0.16 ± 0.07).
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Conclusion A new original biomimetic approach has been developed to synthesize 11C‐norBUP, which was not accessible by the classical radiolabeling routes. The very first PET images of this metabolite in rat brain were recorded, demonstrating in vivo that 11C‐nor‐BUP does not exert its respiratory depressor activity through the interaction with a target located within the brain. ACKNOWLEDGMENTS Supported by CEA‐JOLIOT internal research programs. R EF E RE N C E S 1. Alhaddad, H. et al. Crit. Care Med. 2012, 40 (12), 3215. 2. Luthra, S. K. et al. Appl. Radiat. Isot. 1994, 45 (8), 857.
Poster Category: Radiochemistry ‐ 11C and Other Positron Emitters P-083 | Pd catalyzed cross‐coupling of [11C] MeLi and its application in the synthesis and evaluation of a potential PET tracer for the vesicular acetylcholine transporter (VAChT) Hugo Helbert1; Barbara Wenzel2; Winnie Deuther‐Conrad; Gert Luurtsema3; Wiktor Szymanski; Peter Brust2; Ben Feringa; Rudi Dierckx4; Philip Elsinga3 1
UMC Groningen, Netherlands; 2 Helmholtz‐Zentrum Dresden‐
Rossendorf, Germany; 3 University Medical Center Groningen, Netherlands; 4 UMCG, Netherlands
Introduction The short half‐life of 11C (t1/2 = 20.33 min) requires ultra‐ fast reactivity in order to perform efficient labelling of PET tracers. A recently discovered cross‐coupling methodology1 enables the coupling between aryl bromides and organolithium reagents within seconds and therefore can be an attractive strategy to access 11C‐ labelled compounds. In this work several clinically relevant structures were labelled via this method. The scope
of the reaction was further explored and expanded, allowing radiolabelling of highly reactive compounds, such as aldehydes. Then we focused our attention on the development of a new potential tracer for vesicular acetylcholine transporter (VAChT) which was enabled by this novel cross‐coupling of [11C]MeLi. Methods [11C]MeLi was prepared via lithium‐halogen exchange by trapping [11C]MeI in a solution of n‐BuLi. The prepared [11C]MeLi was further reacted in a Pd catalyzed cross‐coupling reaction with aryl bromides at r.t. for 4 min. After quench and evaporation of the solvent, the mixture was directly purified by HPLC. A series of synthesized vesamicol derivatives were subjected to affinity studies. Results Several clinically relevant structures with application in breast cancer imaging and early diagnosis of Alzheimer's disease had been successfully labelled using this procedure (scheme 1). Employing this same methylation strategy, novel potential tracers for VAChT were synthesized and evaluated in vitro, identifying a compound with good selectivity for VAChT versus σ1 and σ2 and compared to established (‐) FEOBV.
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In vitro affinities measured on rat VAChT (VAChT‐PC12), n = 3; human σ1 (hS1‐HEK293), n = 3; rat σ2 (rat liver), n = 2 Affinity (nM)
(±)1‐Me
(±)2‐Me
(±)3‐Me
(‐)3‐Me
(‐)FEOBV
Ki(VAChT)
8.7 ± 0.1
7.2 ± 1.2
27 ± 18
28 ± 16
7±2
Ki(σ1)
2.1 ± 0.5
5.3 ± 1.7
362 ± 36
382 ± 166
2275 ± 390
Ki(σ2)
373 ± 147
618 ± 257
1650 ± 650
>5000
2118 ± 1058
0.2 : 43
0.7 : 86
13 : 50
14 : >150
>300 : >300
σ1/VAChT : σ2/VAChT
Conclusion A new labelling methodology was successfully applied to the synthesis of clinically interesting radiotracers, providing the purified target molecules in R.C.Y. ranging from 34% to 56% within 30 to 40 minutes (EOB). This procedure offers new opportunities in the development of novel tracers, illustrated by the synthesis of a novel VAChT tracer. 1 Heijnen D, Tosi F, Vila C, Stuart M, Elsinga P, Szymanski W, Feringa B. Angew. Chem. Int. Ed. 2017, 56 (12), 3354‐3359
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-084 | A mild method to activate molecular sieve 13X for [11C]carbon dioxide entrapment and release Shuiyu Lu1; Jinsoo Hong2; William Miller; Victor Pike3 1
National Institutes of Health, United States; 2 National Institute of
Health, United States; 3 National Institute of Mental Health, United States
Objectives Molecular sieves, such as 4A and 13X, are commonly used to concentrate cyclotron‐produced [11C]carbon dioxide and separate the [11C]carbon dioxide from the oxygen used in the cyclotron target before use in radiosynthesis.1,2 Si/Al ratio, the amount and position of exchangeable cations, and the acid‐base properties of the zeolite framework all affect their ability to adsorb carbon dioxide.3 We earlier used molecular sieve 13X that had been activated with prolonged heating (>36 h, 340°C). However, these sieves show decreasing trapping and release efficiency after 4 to 6 months of use. Here we describe a method for quenching the surface of 13X sieves with dilute acid so that they become rapidly and
effectively activated for efficient trapping and release of [11C]carbon dioxide. Methods To monitor pH change, molecular sieves 13X (400 mg, 80/100 mesh, Grace) or 4A (400 mg, 0.4‐0.8 mm beads, Alfa Aesar) were mixed with water (2.0 mL; HPLC grade) in a 25‐mL glass vial. After 10 min, a small aliquot of liquid (50 uL) was sampled for pH measurement. A stock dilute HCl solution (pH = 2.5) was prepared in another 25‐mL glass vial by adding conc. HCl (36%, 30 uL) to water (2.0 mL; HPLC grade). Stock HCl solution (100 uL) was added to the molecular sieves slurry. The pH was measured within 5 min and again after 4 to 12 h. Acid additions and pH measurements were repeated until the pH stayed below 6.0 (Figure 1). The sieves were then separated, washed with water (3 × 2 mL; HPLC grade), and dried (110°C) in hot oven overnight. These sieves were then packed into a stainless steel trap (a component of a radiosynthesis apparatus) and heated at 130°C under helium gas purge (80 mL/min) overnight. For the operation of the trap, cyclotron produced [11C]carbon dioxide
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in target gas mixture (N2‐1% O2) was absorbed in the sieves over 2 to 3 min. The trap was then swept with helium gas (80 mL/min) for 2 min, and heated to 280°C under helium flow to release the radioactivity into a 5‐mL collection V‐vial containing aq. NaOH (1 M, 2 mL). Results Tests showed that untreated 4A or 13X sieves absorbed all [11C]carbon dioxide but never released upon heating (Table 1). The pH of a 4A sieves‐water slurry was 9.0 and that of a 13X‐water slurry, 8.5. The more basic 4A sieves required twice more acid to reach pH 5.5 than 13X sieves (Figure 1). The treated 13X trapped all [11C]carbon dioxide from the target as indicated by absence of radioactivity in a vent waste bag, and released close to 90% of the radioactivity upon heating. The acid treated 13X sieves on average last about 100 runs before losing trapping efficiency and needing to be replaced. Conclusions Dilute acid treatment is effective for activating 13X molecular sieves rapidly under milder conditions for processing of [11C]carbon dioxide before radiosynthetic use. ACKNOWLEDGEMENTS This work was supported by the Intramural Research Program of the National Institutes of Health (NIMH). R EF E RE N C E S 1. Amor‐Coarasa A, Kelly JM, Babich JW, Nucl Med Biol. 2015;42:685–690. 2. Hooker JM, Reibel AT, Hill SM, Schueller MJ, Fowler JS, Angew Chem Int Ed. 2009;48:3482–3485. 3. Pera‐Titus M, Chem Rev. 2014;114:1413−1492.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-085 | CuI‐mediated 11C‐cyanation of (hetero)aromatic bromide and synthesis of [11C]perampanel Hideki Ishii1; Toshimitsu Okamura2; Ming‐Rong Zhang3 1
Technology, Japan; 3 Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
Objectives The introduction of nitrile groups to the organic compounds is one of the most attractive ways for the synthesis of drugs, agriculture, and functional materials. Facile conversion of nitrile group to the other functional groups, such as carboxylic acid, amide, tetrazole, and so on, is also synthetically useful method as well. Generally, the introduction of a nitrile group is conducted with appropriate cyanide source and halogen, pseudo‐halides, stannanes, and organoborons in the presence of transition metal. These methods are also applied for the introduction of [11C]CN, and we have used Rosenmund‐von Braun reaction for this purpose.1 Here we report the CuI‐mediated 11C‐cyanation of (hetero)aromatic compounds. Methods [11C]CN was synthesized by reducing [11C]CO2 to [11C] methane with nickel under H2 atmosphere and then oxidized it with Pt under NH3 atmosphere. The generated [11C]NH4CN was bubbled to a reaction vessel containing CuI and (hetero)aromatic bromide at room temperature. The reaction mixture was heated at 180°C for 5 min, then was purified by reverse phase HPLC to give corresponding [11C]CN labelled products in good radiochemical yields. Results CuI‐mediated 11CN‐labelling has been successfully applied to model heteroaromatic bromide, such as 3‐bromopyridine and 3‐bromoquinoline. Thus, we have applied this method for the synthesis of [11C]perampanel, which was obtained in 30% radiochemical yield (decay corrected to the end of bombardment) with >99% of radiochemical purity and 84 GBq/μmol of molar activity. Conclusions We have successfully achieved CuI‐mediated11CN‐labelling of (hetero)aromatic compounds. Further applications of this reaction are currently under investigation. ACKNOWLEDGEMENTS This work was supported by JSPS KAKENHI Grant Number17K10383.
Department of Radiopharmaceuticals Development, National Institute of
Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 2 National Institute of Radiological
RE FER EN CES
Sciences, National Institutes for Quantum and Radiological Science and
1. Oi, N., Tokunaga, M., et al.,J. Med. Chem. 2015, 58, 8444‐8462.
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P-086 | Synthesis and radiopharmacological evaluation of a C‐11‐labeled azadipeptide nitrile inhibitor for targeting cysteine cathepsins Markus Laube1; Maxim Frizler2; Robert Wodtke3; Christin Neuber4; Ralf Bergmann4; Michael Bachmann3; Michael Gütschow2; Jens Pietzsch5; Reik Loeser6 1
Helmholtz‐Zentrum Dresden‐Rossendorf, Institute of
Radiopharmaceutical Cancer Research, Dresden, Germany; 2
Pharmaceutical Institute, Pharmaceutical Chemistry I, Rheinische
Friedrich‐Wilhelms‐Universität, Germany; 3 Helmholtz‐Zentrum Dresden‐ Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany; 4
Helmholtz‐Zentrum Dresden‐Rossendorf, Germany; 5 Helmholtz‐
Zentrum Dresden‐Rossendorf, Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Germany; 6 Helmholtz‐Zentrum Dresden‐Rossendorf, Institute of Radiopharmaceutical Cancer Research, Germany
Objectives Cysteine cathepsins are important players in various human diseases like diabetes mellitus, cardiovascular diseases, and cancer.1 With regards to molecular imaging of cysteine cathepsins by positron emission tomography (PET), 11C‐, 18F‐, 64Cu‐, and 68Ga‐labeled radiotracers based on irreversibly acting acyloxymethyl ketone inhibitors and nitriles, which inhibit the enzymes in a covalent‐reversible manner, have been developed. Based on a 18F‐fluoroethylated azadipeptide nitrile previously presented by us,2 we herein present the radiosynthesis and radiopharmacological evaluation of the respective 11 C‐methylated compound to allow comparison between both complementary radiolabeling approaches. Methods The O‐methyltyrosine‐containing azadipeptide nitrile 1 was synthesized and investigated for its inhibitory activity towards cathepsin L, S, K, and B. Labeling with carbon‐11 was accomplished starting from cyclotron‐produced [11C] methane by conversion to [11C]methyl iodide in the gas phase, subsequent reaction with the corresponding phenolic precursor and final purification by semi‐preparative HPLC. Radiopharmacological evaluation of the resulting radiotracer [11C]1 was performed in a mouse xenograft model derived from a mammary tumor cell line by small animal PET imaging.
Results The methoxy‐substituted azadipeptide nitrile 1 showed highly potent inhibition of thiol‐dependent cathepsins with Ki values in the high picomolar (L, S, K) to single‐ digit nanomolar (B) range. The radiosynthesis was performed in an automated synthesis module TracerLab‐ FXCPro. For 11C‐methylation, the base was optimized and NaH was found to be superior compared to DBU and NaOH. Starting from [11C]CH4, radiolabeling of [11C]1 under optimized reaction conditions was achieved in an isolated radiochemical yield of 13.6 ± 1.6 % (n = 10) with high radiochemical purity (98.7 ± 0.2% determined by radio‐HPLC) and a molar activity of 62.6 ± 8.1 GBq/μmol (n = 6). Small animal PET in MDA‐MB‐231 tumor‐bearing mice with and without pharmacological inhibition (non‐radioactive 1, E64) provides proof for a cysteine cathepsin‐mediated tumor uptake. However, the inherent thiol reactivity, which also has been observed for the 18F‐fluoroethylated analog, determines a complex pharmacokinetic behavior and in turn the limited suitability of [11C]1 for the imaging of cysteine cathepsins in vivo. Conclusion [11C]1 was synthesized in a reliable, remotely‐controlled procedure and investigated in tumor‐xenograft bearing mice. Comparative small animal PET imaging for control and blocking with inhibitors demonstrated the capability of azadipeptide nitriles of targeting cysteine cathepsins in vivo, even though with complex pharmacokinetics. Therefore, the in vivo behavior observed for this 11C‐labeled radiotracer largely confirms that of the corresponding 18F‐fluoroethylated analog and suggests the limited suitability of azadipeptide nitriles in general for imaging of tumor‐associated cysteine cathepsins. RE FER EN CES 1. Reiser et al. J. Clin. Invest. 2010, 120, 3421‐3431 2. Löser et al. ChemMedChem 2013, 8, 1330‐1344
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P-087 | New trends in cross‐coupling 11C‐ methylation Francois Liger1; Thibaut Iecker2; Christian Tourvieille2; Didier le Bars3; Thierry Billard1 1
CNRS–CERMEP, France; 2 CERMEP, France; 3 CERMEP Imgerie du
Vivant, France
Objectives Many drug‐like molecules contains heteroaromatic cycles in their structures. Therefore the introduction of [11C] methyl substituent on a heteroaromatic ring presents a great interest for PET tracer developments. The palladium (0) mediated 11C‐methylation with aryl, alkenyl, and benzylic boronic esters is a robust method for the synthesis of 11 C‐methylated PET Tracers.1 Although this 11C‐methylation reaction have been applied towards heteroatom‐ containing compounds, the formation of [11C]CH3‐aromatic bonds by Suzuki coupling2 is actually limited to aryl moieties and not directly to heteroarene cores. Availability of boronic precursors, generally achieved by a palladium (0) catalyzed borylation of corresponding halogeno‐ derivatives,3 could also restrict the field of application. The development of a simple procedure of palladium (0) mediated 11C‐methylation from halogeno‐arenes could be valuable. Methods Various commercially available heteroaromatic boronic acids and derivatives were submitted to optimized palladium (0) mediated cross coupling 11C‐methylation. In addition, reactivity of [11C]CH3I towards crude arylboronic derivatives, generated in situ, was tested in a one pot two‐steps procedure. Results 11 C‐methylated‐heteroaromatics molecules were successfully produced in 5 minutes reaction time, in a maximum overall radiosynthesis time of 45 minutes, with radiochemical yields ranging from 3 to 74% (EOB). Influence of the purity of starting boronic derivatives, time, and temperature reaction will be presented. Conclusions The Suzuki coupling is a versatile method for the 11 C‐labelling of heteroaromatics molecules and the scope of the labelling process could be extended thanks to a simplify two steps procedure.
RE FER EN CES 1. T. C. Wilson, T. Cailly, V. Gouverneur, Chem. Soc. Rev. 2018, 47, 6990‐7005. 2. H. Doi, I. Ban, A. Nonoyama, K. Sumi, C. Kuang, T. Hosoya, H. Tsukada, M. Suzuki, Chem. ‐ Eur. J. 2009, 15, 4165‐4171. 3. T. Ishiyama, M. Murata, N. Miyaura, J. Org. Chem. 1995, 60, 7508‐7510.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-088 | Rhodium‐catalyzed addition of organozinc iodides to [11C]isocyanates Braeden Mair; Moustafa Fouad1; Uzair Ismailani; Benjamin Rotstein2 1
University of Ottawa, Canada; 2 University of Ottawa & University of
Ottawa Heart Institute, Canada
Objectives Amides are a prodigious functional group in medicinal chemistry. However, many powerful and versatile synthetic strategies for their bond formation using stable isotopes prove ineffective or impractical for carbon‐11.1 We have developed a method capable of generating [11C]amides in suitable yields for radiotracer development. Methods Organozinc iodides were prepared through zinc insertion reactions into aryl and alkyl iodides2 before undergoing rhodium mediated reactions with substituted isocyanates to produce amide products in moderate yields (10–87%). This approach was further carried out with the use of in situ prepared [11C]isocyanates3 using a Synthra MeIplus Research module for the preparation of [11C] amides.
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Results A diverse substrate scope was prepared using aryl and alkyl organozinc iodides with a variety of substituted isocyanates. Aryl zinc iodides produced a range of substituted benzamides with yields from 21‐87%. Couplings using alkyl zinc iodides were less selective but still derived amides in yields from 10–64%. The use of electron‐ withdrawing groups on the isocyanate provided superior yields (alkyl: 41‐60%, aryl: 79‐87%) compared to those with electron‐donating groups (alkyl: 10‐32%, aryl: 30‐62%). This was best demonstrated with products 1a N‐(4‐ trifluoromethylphenyl)benzamide (87%) and 1b N‐(2‐ methoxyphenyl)benzamide (30%). Sterically hindered isocyanates could be tolerated (alkyl: 10‐32%, aryl: 39‐62%), for example, product 1c N‐(2‐methylphenyl) propanamide (32%), as well as aliphatic isocyanates coupled with aryl zinc iodides, such as 1d N‐(benzyl) benzamide (57%). These results with stable isotopes informed the development of a radiochemical method and directed the optimization for the synthesis of [11C]1e, [11C]acetanilide, to provide radiochemical conversions of >90%. Applications for the radiolabeling of additional biologically relevant compounds demonstrate the synthetic utility of the method. Conclusions We have developed a radiosynthesis for the preparation of [11C]amides from cyclotron‐produced [11C]CO2 using rhodium‐mediated reactions between organozinc iodides and in situ prepared [11C]isocyanates that provides suitable yields for continued radiotracer development. ACKNOWLEDGEMENTS This work was supported by NSERC and BioTalent Canada. R EF E RE N C E S 1. Rotstein et al. Chem. Soc. Rev. 2016, 45, 4708–4726. 2. Krasovskiy et al. Angew. Chem. Int. Ed. 2006, 45, 6040–6044. 3. (a) Haji Dheere et al. Chem. Commun. 2013, 49, 8193–8195. (b) Bongarzone et al. Chem. Commun. 2017, 53, 5334–5337.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-089 | Facile radiosyntheses of [11C] tetrazoles and [11C]triazines from (hetero) arylborons Zhouen Zhang; Takashi Niwa; Yasuyoshi Watanabe; Takamitsu Hosoya RIKEN Center for Biosystems Dynamics Research, Japan
Objectives PET tracers containing a carbon‐11 (11C) in their cyclic skeleton such as [11C]uric acid1 or [11C]phenytoin2 have been synthesized via cyclization with [11C]phosgene or [11C]carbon monoxide, respectively. However, the range of available skeletons labeled with 11C is largely limited and development of intracyclic 11C‐labeling methods still remains a critical issue. Here, we have achieved intracyclic 11 C‐labeling of tetrazoles and triazines, which are basic frameworks frequently found in bioactive molecules. Methods [11C]Tetrazoles and [11C]triazines were synthesized from (hetero)arylborons by 11C‐cyanation and subsequent cyclization reactions conducted in a one‐pot manner (Figure 1A). The 11C‐cyanation of (hetero)arylborons were performed using our palladium (II)‐mediated method for the synthesis of [cyano‐11C]aromatic nitriles.3 The subsequent cyclization reactions were performed in the same flask using trimethylsilyl azide (TMSN3) or dicyandiamide to afford [11C]5‐aryltetrazoles or [11C]2,4‐diamino‐6‐aryl‐1,3,5‐triazines, respectively. The radiochemical yields (RCYs) based on [11C]NH4CN were determined by radio‐HPLC analysis of the reaction mixture. Results Fifteen kinds of [11C]5‐aryltetrazoles bearing various functional groups were synthesized from the corresponding (hetero)arylboronic acids or pinacol esters (Figure 1A). The RCYs based on [11C]NH4CN were up to 95 ± 4%. Furthermore, eight types of [11C]2,4‐diamino‐6‐aryl‐1,3,5‐ triazines were also smoothly synthesized in RCYs up to 89 ± 14% based on [11C]NH4CN. These intracyclic 11C‐ labeling methods were successfully applied to the synthesis of 11C‐labeled celecoxib analog (COX‐2 inhibitor) and [11C]irsogladine (phosphodiesterase inhibitor), demonstrating the utility of these methods for preparing functional PET tracers (Figure 1B). Conclusions Radiosyntheses of [11C]5‐aryltetrazoles and [11C]2,4‐ diamino‐6‐aryl‐1,3,5‐triazines from (hetero)arylborons have been achieved by rapid 11C‐cyanation and subsequent cyclization. These methods showed high functional group tolerance enabling efficient synthesis of a wide range of [11C]tetrazoles and [11C]triazines, including functional PET tracers. ACKNOWLEDGEMENTS This work was supported by JSPS KAKENHI 16K08339, J‐AMED under Grant Numbers JP18am0101098, the Pioneering Project “Chemical Probe” from RIKEN, and JSPS A3 Foresight Program.
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R EF E RE N C E S 1. K. Yashio, Y. Watanabe, et al. Bioorg. Med. Chem. Lett. 2012, 22, 115. 2. J. Verbeek, et al. EJNMMI Research, 2012, 2, 36. 3. Z. Zhang, T. Hosoya, et al. J. Label. Compd. Radiopharm. 2017, 60, S48; Z. Zhang, T. Hosoya, et al. Org. Biomol. Chem. 2018, 16, 7711.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-090 | Expanding the scope of carbon‐11 labelled ureas: A universal method to access short‐lived click reagents for in vivo PET imaging Salvatore Bongarzone; Alessandra Ferocino; Antony Gee King's College London, United Kingdom
Objectives In vivo studies with labelled biomolecules using longer lived PET radionuclides (eg, 89Zr, radioactive half‐life 3.3 days) have some limitations due to dosimetry constraints, image quality, and difficulty in monitoring biomolecule biodistribution and kinetics for extended periods (>7 days). The pretargeting approach using carbon‐11 clickable radiolabelled compounds (11C‐CRCs) is, however, an attractive alternative strategy, enabling multiple time point biomolecule imaging with superior counting statistics. Mikula H. et al have recently developed a 11C‐CRC to react with cyclooctene‐modified nanoparticles in vivo.1 However, this particular 11C‐CRC was only obtained after a relatively long (30 min) synthesis
time with moderate radiochemical yields (52%), using a tertiary cyclotron synthon ([11C]methyl triflate) and a precursor prepared by a multi‐step synthesis. For this approach to be viable, we propose that ready‐to‐use 11C‐ CRC's should be produced rapidly, efficiently, and without time‐consuming purification steps. We have now extended the application of the rapid 11C‐urea synthesis method developed in our laboratory2 to design 11C‐clickable ureas as a generic method for in vivo pretargeting approaches, Figure 1A. “Ready‐for‐use” 11C‐CRU's were obtained via a simple, rapid, and versatile approach, starting from cyclotron‐produced [11C]carbon dioxide ([11C]CO2) within 5 min from end of bombardment using commercially available precursors, Figure 1B. Methods Cyclotron‐produced [11C]CO2 was bubbled directly from the cyclotron target into a reaction vial containing an amine and DBU in acetonitrile (MeCN). In a separate vial, PBu3 was added to a solution containing DBAD in MeCN under nitrogen at r.t. The resulting solution was transferred into the reaction mixture and stirred for
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2 min at 100°C. The reaction was quenched with H2O and the crude product analysed by radio‐HPLC. Results After a total synthesis time of 5 min from end of [11C]CO2 delivery, [11C]1 was obtained with an average of 99% [11C]CO2 trapping efficiency and a crude product radiochemical purity of ca. 50% and non‐isolated radiochemical yield of 49%, determined by radio‐HPLC (Figure 1C). Rapid SPE purification of [11C]1 is currently under optimisation. Conclusions The rapid radiosynthesis of the novel 11C‐CRU derivative ([11C]1) has been successfully developed for in vivo pretargeting applications. In vivo proof‐of‐concept studies to determine the utility of this approach for monitoring the pharmacokinetics and biodistribution of 11C‐CRU and pre‐administered cyclooctene‐ or azide‐modified biomolecules with PET are in progress. R EF E RE N C E S 1. Denk, C., et al. Bioconjug Chem 2016, 27, 1707‐12. 2. Dheere, A. K. H., et al. Synlett 2015, 26, 2257‐2260.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-091 | Rapid one‐step carbon‐11 carboxylation of terminal alkynes using [11C] CO2. Francesca Goudou; Salvatore Bongarzone; Antony Gee King's College London, United Kingdom
Objectives A plethora of 11C‐tracers are accessible via [11C]carboxylic acid labelling approaches. To date, there are two ways to obtain [11C]carboxylic acids from [11C]CO2: by direct carboxylation of Grignard reagents1 or by reaction with aromatic boronic esters2. Grignard reagents have a widespread use but are highly reactive species, incompatible with many functional groups and air and moisture sensitive, producing lower molar activities of 11C‐ tracers unless used with great care.1 Boronic esters show a greater substrate scope but are restricted to aromatic and vinyl aromatic boronate esters.2 F.W. Li et al have developed an organic solvent free, DBU (1,8‐
Diazabicyclo[5.4.0]undec‐7‐ene)‐mediated, and copper(I)‐catalyzed carboxylation of terminal alkynes using non‐radioactive CO2.3 In this work, we have extended this methodology to obtain [11C]propiolic acids from [11C]CO2 (Scheme 1). Methods Cyclotron‐produced [11C]CO2 was bubbled directly into a solution of an acetylene derivative (1a‐4a), DBU (1,8‐ Diazabicyclo[5.4.0]undec‐7‐ene), copper iodide (CuI), and acetonitrile (ACN) stirred at 0°C. After 2 minutes at 100°C, the reaction was quenched with formic acid 10% in ACN at 0°C and the vial flushed with helium for 3minutes at 20°C. Results After a total synthesis time of 16 minutes from end of [11C]CO2 delivery, the [11C]phenylpropiolic acid ([11C]1b) was obtained with an average of 34% [11C]CO2 trapping efficiency and a crude product radiochemical purity of ca. 90%, determined by radio‐HPLC, giving a non‐isolated radiochemical yield (RCY) of 30% based on trapped [11C]CO2, decay corrected to end of the bombardment (EOB) and with an activity yield of 18%. [11C]2b‐4b have been synthesised with an average RCY of 12‐33% (from [11C]CO2). Conclusions A novel route to aromatic and aliphatic 11C‐propiolic acids starting from the corresponding alkyne derivatives and cyclotron produced [11C]CO2 has been developed. Work is in progress to apply this model reaction to radiolabel PET radiotracers for in vivo imaging. RE FER EN CES 1. B. H. Rotstein, S. H. Liang, J. P. Holland, T. L. Collier, J. M. Hooker, A. A. Wilson and N. Vasdev, Chem. Commun., 2013, 49, 5621–5629 2. P. J. Riss, S. Lu, S. Telu, F. I. Aigbirhio and V. W. Pike, Angew. Chem., Int. Ed., 2012, 51, 2698–2702 3. F. W. Li, Q. L. Suo, H. L. Hong, N. Zhu, Y. Q. Wang, L. M. Ham, Tetrahedron lett., 2014, 55, 3878–3880.
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Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-092 | Synthesis of [11C]nicotinamide analogs for imaging of nicotinamide N‐methyltransferase activity Toshimitsu Okamura1; Hideki Ishii2; Tatsuya Kikuchi3; Maki Okada; Hidekatsu Wakizaka; Ming‐Rong Zhang4 1
National Institute of Radiological Sciences, National Institutes for
Quantum and Radiological Science and Technology, Japan; 2 Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3 National Institute for Quantum and Radiological Science and Technology, Japan; 4 Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
Objectives Nicotinamide N‐methyltransferase (NNMT) catalyzes the N‐methylation of nicotinamide and various closely related structural analogs to form positively charged pyridinium ions and contributes to the nicotinamide clearance and xenobiotic detoxification. NNMT is expressed primarily in the liver but has been found in other tissues at lower levels. Recent studies have shown relationships between changes in NNMT expression and several diseases. In the brain, Parkinson's disease patients have higher levels of NNMT protein and activity compared with normal subjects. In vivo imaging of NNMT activity would therefore be helpful for elucidation of pathological conditions. Here, we present the synthesis of [11C]nicotinamide analogs for imaging NNMT activity in the brain. To find a blood‐brain barrier permeable tracer with the moderate methylation rate, which is required for NNMT imaging, five candidate tracers were designed in consideration of kinetic parameters of NNMT substrates.1 Methods [11C]Nicotinamide, 4‐methyl[11C]nicotinamide, and 3‐ quinoline[11C]carboxamide were synthesized by the Pd(0)‐mediated [11C]carbomethoxylation of the corresponding pinacol esters with [11C]carbon monoxide in methanol followed by hydrolysis with aqueous ammonia solution. [11C]Thionicotinamide and 4‐methylpyridine‐ 3‐[11C]carbothioamide were synthesized by the thoiamidation of the corresponding [11C]cyanopyridines using sodium hydrogen sulfide in N,N‐dimethylformamide (DMF) at 90°C. The [11C]cyanopyridines were prepared by the reaction of the bromo precursors with [11C]ammonium cyanide in DMF at 180°C.
Results The radiochemical yields of the isolated [11C]nicotinamide, 4‐methyl[11C]nicotinamide, 3‐quinoline[11C] and 4‐ carboxamide, [11C]thionicotinamide, methylpyridine‐3‐[11C]carbothioamide from [11C]carbon dioxide were 2.7 ± 1.1%, 4.3 ± 3.5%, 5.4 ± 0.1%, 7.8 ± 6.6%, and 4.0 ± 3.5% (decay corrected to the end of bombardment), respectively. Their radiochemical purities were >95%, and molar activity was in the range of 7.4 to 82 GBq/μmol at the end of synthesis. Conclusions We have achieved the synthesis of the candidate tracers, [11C]nicotinamide analogs, for imaging NNMT activity in the brain. Further in vivo studies are in progress. RE FER EN CES 1. van Haren MJ et al., Biochemistry, 2016, 55, 5307−5315
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-093 | Novel 11C‐labeled and 18F‐labeled allosteric modulators for M4 imaging Xiaoyun Deng1; Zhen Chen1; Xiaofei Zhang2; Tuo Shao1; Shaofa Sun3; Yihan Shao4; Lee Josephson1; Steven Liang1 1
MGH/Harvard, United States; 2 MGH/Harvard, China; 3 College of
Nuclear Technology & Chemistry and Biology, Hubei University of Science and Technology, China; 4 University of Oklahoma, United States
Objectives A small array of pyrazol‐4‐yl‐pyridine compounds were identified as positive allosteric modulators (PAMs) of the muscarinic acetylcholine receptor subtype 4 (M4). These molecules described herein are designed to provide potential treatment and/or prevention of neurological and psychiatric disorders.1,2 The goal of the project was (a) to synthesize several representative M4 PAMs amenable for labeling, (b) to determine potency and selectivity using functional assays, and (c) to radiolabel potent M4 PAMs with carbon‐11 or fluorine‐18. Methods Alcohol 1 was mesylated with MsCl to form intermediate 2 in 95% yield under basic conditions. N‐Alkylation of pyrazole boronic ester gave a new boronic ester 4 in 75% yield. Sequential Suzuki coupling reactions afforded compound 8. Specifically, palladium‐mediated reactions
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between bromide 5 and boronic acid ester 4 generated 6 in 53% yield, followed by the second coupling between ensuing chloride 6 and boronic acid ester 7a in 64% yield. The analogous procedure was applied to obtain amide precursor 9 in 66% yield. N‐Alkylation of 9 could also afford 12 and 13 in 37‐39% yields and their 18F‐ radiolabeling precursors 14 and 15 in yields of 14‐40%. Pyrazol‐4‐yl‐pyridine 8 and its five derivatives (9‐13) were subsequently screened for their in vitro activity toward M1, M2, M3, M4, and M5 using cell‐based calcium release functional assay. Preliminary 11C‐labelings were carried out using amide precursor 9 and 11, respectively with
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[11C]methyl iodide in the presence of KOH in DMSO (0.4 mL) at 130°C for 5 min to generate [11C]8 or [11C]10. Preliminary 18F‐labeling was carried out using precursor 14, which was prepared from compound 9 and TsOCH2CH2OTs, with [18F]fluoride in the presence of TBAOMs at 100°C for 10 min to yield tracer 12. Ex vivo whole‐body distribution and radiometabolite analysis of pyrazol‐4‐yl‐pyridine [11C]8 have been performed to evaluate and develop potent and selective M4 PET tracers. Result The synthesis of standard 8 and its close analogs 9‐13 for the pyrazol‐4‐yl‐pyridine were achieved in four steps with
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overall 20‐25% yields. All six candidates showed high potency (EC50 values 37.8 nM for 8, 70.6 nM for 9, 97.3 nM for 10, 201.7 nM for 11, 33.0 nM for 12, and 37.2 nM for 13 in average two independent runs) at M4 and excellent selectivity (>100 fold) for M4 over M1, M2, M3, and M5. Radiolabeled pyrazol‐4‐yl‐pyridine [11C]8 or [11C]10 was generated in 2‐3% isolated radiochemical yield (non‐decay corrected from starting [11C]CO2) with greater than 40 GBq/μmol molar activity. The reaction between [18F]fluoride and precursor 14 generated radiolabeled pyrazol‐4‐yl‐pyridine [18F]12 in 19 ± 5% isolated radiochemical yield (non‐decay corrected). The uptake, distribution, and clearance of [11C]8 was studied in CD‐1 mice at four time points (5, 15, 30, and 60 min) post‐injection. High uptake (>3% ID/g) was observed in the heart, lungs, liver, pancreas, kidneys, and small intestine at 5 min post injection of [11C]8. After the initial phase, the radioactivity levels in most tissues decreased rapidly, while the signals in the small intestine continually increased until 15 min, then declined. Conclusion We have successfully prepared six potent and selective pyrazol‐4‐yl‐pyridine for M4 PAM and conducted in vitro pharmacological evaluation. The radiolabeled [11C]8, [11C]10, and [18F]12 were produced in reasonable isolated yields and high molar activity. Further PET imaging studies will be carried out to evaluate top candidate M4 PAMs. R EF E RE N C E S 1. Neuropsychiatr Dis Treat. 2014; 10: 183–191; 2. WO2017112556.
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-094 | Challenge of [11C]pirenzepine radiosynthesis: structure analysis of a novel rearrangement product Marius Ozenil; Lukas Skos; Alexander Roller; Chrysoula Vraka; Helmut Spreitzer; Markus Mitterhauser; Marcus Hacker; Wolfgang Wadsak; Verena Pichler Department of Biomedical Imaging and Image‐guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria
Objectives Pirenzepine is a muscarinic acetylcholine receptor M1 selective antagonist and is market authorized for inhibition of gastric secretions. Although pirenzepine does
not penetrate the blood‐brain barrier and is therefore not suitable for clinical neuroimaging studies using PET, it is nevertheless widely applied in in vitro and ex vivo binding studies. During the the set‐up of the [11C]pirenzepine radiosynthesis as reference compound for preclinical studies, we identified a major rearrangement product of pirenzepine, which is hard to distinguish and therefore can significantly aggravate experimental results. The aim of this study was to identify the reaction conditions for the rearrangement reaction and as a result a possibility to avoid this side reaction. Additionally, we investigated the possibility of a similar rearrangement reaction for the pirenzepine derivatives AFDX‐384 1 and telenzepine. Methods [11C]CO2 was produced with a GE PETtrace 860. The conversion of [11C]CO2 to [11C]CH3I radiochemical synthesis of [11C]pirenzepine was performed on a GE Tracerlab FX C Pro. Quality control consisted of the identification of the radiochemical and chemical purity via RP‐HPLC, pH, osmolality, and gas chromatography for residual solvents. Reaction conditions for the rearrangement reaction were tested in acidic aqueous solutions and in artificial gastric acid at different temperatures. For identification of the rearrangement product, an RP‐HPLC method was established. Full characterization of this side product was performed by means of ESI‐MS, NMR, as well as X‐ray crystallography. Both, pirenzepine and the rearrangement product were tested for their affinities on CHO membranes expressing human M1‐M5 receptors as well as their lipophilicity by means of the RP‐HPLC method by Donovan and Pescatore.2 Results [11C]pirenzepine was produced in radiochemical yields of 3.9 ± 0.5 GBq. The rearrangement reaction occurred at low pH (6 M HCl) and elevated temperatures nearly quantitatively within 1.5 hours and was continuously monitored with the RP‐HPLC. The structure of the rearrangement product was identified and confirmed via X‐ray crystallography. There is a dramatic reduction of the binding affinity of the rearrangement product to the human M1 receptor from Ki = 16 nmol/L to 600 nmol/L. Furthermore, also the lipophilicity was found to be lower than that of pirenzepine, namely a logPowpH7.4 of −1.48 ± 0.65 compared to −0.70 ± 0.54, respectively. Finally, we could identify similar side reactions for AFDX‐384 and telenzepine. Conclusion A side product of pirenzepine synthesis with a literature‐ unknown structure could be identified and analysed. As this side product is difficult to distinguish, we established
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a reliable RP‐HPLC method to identify this impurity, especially as it offers an approx. 40‐fold reduced affinity. Therefore, its presence in [11C]pirenzepine solutions would significantly change experimental results in terms of binding profile and displacement behaviour. R EF E RE N C E S 1. Valuskova P, Farar V, Forczek S, Krizova I, Myslivecek J “Autoradiography of 3H‐pirenzepine and 3H‐AFDX‐384 in Mouse Brain Regions: Possible Insights into M1, M2, and M4 Muscarinic Receptors Distribution.” Front Pharmacol 2018 Feb 20;9:124. 2. S.F. Donovan, M.C. Pescatore “Method for measuring the logarithm of the octanol–water partition coefficient by using short octadecyl‐poly (vinyl alcohol) high‐performance liquid chromatography columns” J Chromatogr A, 952 (2002), pp. 47‐61
Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-095 | Application of new positron imaging agent 68Ga‐pentixafor PET/CT in primary aldosteronism Jie Ding; Luo Yaping; Pan Qingqing; Li Fang; Tong Anli; Zhang Yushi; Huo Li Chinese Academy of Medical Science & Peking Union Medical College, Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, China
Objectives Primary aldosteronism (PA) is the most common cause of secondary hypertension. There are two common types of PA, unilateral aldosterone‐producing adenoma (APA) and bilateral idiopathic hyperaldosteronism (IHA). Surgery is main treatment for APA,while drug is for IHA. In addition, essential hypertension associated with nonfunctioning adenomas (NFA) is also difficult to distinguish with APA sometimes. Recently, some researchers found that C‐X‐C chemokine receptor type 4 (CXCR4) is highly expressed in APA, but not in NFA or IHA.1 Hence, a promising CXCR4‐specific ligand, 68Ga pentixafor has been introduced for clinical molecular imaging of CXCR4 expression. Our research aims to evaluate the application of 68Ga‐pentixafor PET/CT in patients with PA, especially in APA. Methods Twelve patients (6 males and 6 females, 45 ± 8 years old) with clinically suspected of PA and four patients(2 males and 2 females, 47 ± 7 years old)with NFA were included in the study. Totally 18 adrenal glands nodules were confirmed by CT/MRI (14 patients with unilateral and 2 with bilateral nodules). 68Ga pentixafor PET/CT images were acquired on PoleStar m660 for 30 min, and the injection dose was 25.9‐62.9(44.4 ± 11.1)MBq. After OSEM+TOF reconstruction, semi‐quantitative analysis was performed by two experienced nuclear medical physicians to calculate the SUVmax (Maximum standardized uptake values) of lesions, adrenal to liver ratio (ALR), and lesion to a contralateral ratio (LCR).
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All patients were followed up for 1‐4 months and diagnosed depending on postoperative follow‐up (14 cases) and AVS results (2 cases). Results Minor diffuse accumulation of 68Ga pentixafor (SUVmax 2.95 ± 1.40, ALR 1.40 ± 0.87) were found in normal adrenal glands. Among 18 nodules of 16 patients, 11 were finally diagnosed as APA (1.48 ± 0.30 cm), 1 was IHA (0.9 cm) and 6 were NFA (2.02 ± 0.50 cm). The uptake of 68Ga pentixafor in APA was significantly higher than those in IHA and NFA. SUVmax were 10.84 ± 9.71, 4.85, and 4.31 ± 2.63, respectively. The smallest positive APA recognized by PET/CT images was 1.0 × 0.8 cm. Same results were observed in ALR and LCR studies, and the ratios of APA were 3.89 ± 3.09 and 3.94 ± 3.76.1.03, and 1.46 were calculated in IHA. For NFA, they were 1.27 ± 0.97 and 1.57 ± 0.56. In one patient with bilateral adrenal glands nodules, APA were recognized properly depending on high avidity in APA (SUVmax 34.99) while mild (SUVmax 4.12) in NFA in the contralateral adrenal glands (Figure 1). However, to the other patient with bilateral adrenal glands nodules, both 68Ga pentixafor PET/CT and AVS results were negative, the patient recovered from hypertension after one nodule (1.7 × 1.6 cm, SUVmax2.5) resection. Conclusions 68 Ga‐pentixafor PET/CT would be a useful tool in differentiating APA patients from those with IHA and NFA. Our results from 18 nodules of 16 patients studies support those of first literature report in which only 9 patients were included1; however, more evidence is needed to confirm 68 Ga‐pentixafor PET/CT clinical efficiency in APA diagnosis. Figure 1. A 48‐year‐old male patient with hypertension and hypokalemia for 10 years was clinically suspected PA. 68Ga‐ pentixafor PET/CT was performed before the operation. A, CT found a 2.0 × 1.5 cm nodule in right adrenal, and a 0.8 × 0.5 cm nodule in left. B, The fusion found that the metabolism of the right adrenal nodules was significantly increased (Red Arrow), the SUVmax was 34.99, the ALR was 8.9, and the LCR was 14.83. while the left adrenal nodule's SUVmax, ALR and LCR were 4.12, 1.05, and 1.75, respectively (White Row). Later, the patient underwent a right adrenal nodule resection. The pathological result was adrenal adenoma. His blood pressure and serum potassium decreased to normal range after the operation. R EF E RE N C E 1. Heinze, B. et al. Targeting CXCR4 (CXC Chemokine Receptor Type 4) for Molecular Imaging of Aldosterone‐Producing Adenoma. Hypertension (Dallas, Tex: 1979) 71, 317‐325, doi:https:// doi.org/10.1161/hypertensionaha.117.09975 (2018).
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Poster Category: Radiochemistry ‐ Other Positron Emitters
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P-096 | A “Universal” Method for Rapid 11C‐ Radiolabeling of PSMA Targeted Ligands via [11C]CO2 Fixation Joseph Downey; Francesca Goudou; Salvatore Bongarzone; Antony Gee King's College London, United Kingdom
Objectives Prostate specific membrane antigen (PSMA) is a well validated target for PET imaging of prostate cancer (PC). An essential feature in all PSMA‐targeted ligands is an amino acid substituted glutamate‐urea targeting moiety. We therefore aim to develop a “universal” method for the 11 C‐radiolabeling of this essential pharmacophore via direct [11C]CO2 fixation chemistry. By radiolabeling at the common urea‐carbonyl position, negating the usual structural elaboration required for the incorporation of 68 Ga/18F, this methodology will enable the development of ultra‐high affinity 11C‐PSMA radiotracers suitable for the detection of micrometastatic PC lesions. In addition, this could facilitate further study into the effects of sidechain size, charge, and lipophilicity on the pharmacokinetic characteristics of both new and existing PSMA‐ targeted ligands, without the necessary structural compromise normally associated with radiolabeling these compounds. Here we report a novel, general method for the [11C]CO2 fixation mediated radiosynthesis of PSMA‐targeted ligands. As a proof‐of‐concept, we have radiolabeled 3 high‐affinity PSMA ligands: [ureido‐11C] leucine‐glutamate urea ([11C]Leu‐Glu, ki = 0.8 nM),1 currently used non‐radioactively as a blocking agent (ZJ43) in the assessment of other PSMA radiotracers; [ureido‐ 11 C]tyrosine‐glutamate urea ([11C]Tyr‐Glu, 3.0 nM);2 and [ureido‐11C]phenylglycine‐glutamate urea ([11C]Phg‐ Glu, 2.1 nM).2 Methods [11C]CO2 was bubbled for through a solution of L‐glutamic acid di‐tert‐butyl ester (Glu‐(OtBu)2, 5 μmol) and BEMP in acetonitrile (MeCN) over 2 minutes at 20°C. The reaction was heated to 50°C and a solution of POCl3 (21.4 μmol) in MeCN was added and stirred for 2 minutes to form an in‐situ isocyanate. A solution of tert‐butyl protected amino acid (50 μmol) and BEMP in MeCN was added and stirred for 1 minute. The MeCN is evaporated with helium flushing at 100°C for 5 minutes. HCl (12M) was added and stirred at 90°C
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for 2 minutes to remove the tert‐butyl protecting groups before dilution and analysis/purification by reverse‐ phase HPLC. Results
acidic deprotection conditions and should therefore be considered if a tert‐butyl protecting‐group strategy is to be employed. Conclusions
These reactions were complete within 13 minutes from the end‐of‐bombardment (EOB) and exhibit good reproducibility, versatility and radiochemical yields (RCY). The BEMP/POCl3 mediated [11C]CO2 fixation reaction3 produced the tert‐butyl protected urea intermediates in‐ situ; the use of an excess of POCl3 resulted in a good selectivity (>80%) for the asymmetric urea formation versus symmetric. These intermediates were subsequently deprotected with HCl in a one‐pot reaction to produce [11C]Leu‐Glu (38% RCY), [11C]Tyr‐Glu (53% RCY), and [11C]Phg‐Glu (41% RCY). One unexpected result of note was the formation of a cyclised pyroglutamate degradation product (detected by HPLC, MS, and NMR) during the acidic‐hydrolysis of the tert‐butyl esters, in both radioactive and non‐radioactive experiments. While this cyclisation step is very slow relative to the rate of ester hydrolysis (99% enantiomeric excess (ee) synthesis of [11C]D‐methionine from a linear D‐homocysteine precursor, a significant improvement over the previously reported synthesis utilizing a D‐homocysteine thiolactone hydrochloride precursor with 85% ee. Methods and Results Utilizing a previously reported method,1 taken together with our need for an improved synthesis of [11C]D‐methionine,2 we describe the following radiosynthesis: [11C]CO2 was produced via the 14N(p,a)11C nuclear reaction with proton bombardment of nitrogen‐14 spiked with oxygen in the UCSF radiopharmaceutical facility. [11C]CO2 is trapped on a molecular sieve with nickel at room temperature. This is sealed and heated to 350°C with H2 to reduce [11C]CO2 to [11C]CH4, which is trapped on a carbosphere methane trap previously cooled to −80°C with liquid N2. The carbosphere is heated to release the [11C]CH4 which enters a recirculation loop containing an iodine column at 90°C. The recirculation tube reactor is maintained at 750°C and [11C]CH4 is converted to [11C]CH3I over a period of 5 min. The converted [11C]CH3I is trapped on a porapak column at room
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temperature. A stainless steel HPLC loop was previously coated with 100 μl of a solution containing 1.25 mg of D‐homocysteine in 0.5M NaOH in 50/50 H2O/EtOH, followed by 300‐500 μl of air to coat the loop before being placed in the synthesis module. The porapak column is heated to 180°C and the [11C]CH3I is flowed through the loop at 15 mL/min for 70‐90 seconds and allowed to sit for 1 min at room temperature. The loop is rinsed with two additions of 3 mL saline to an intermediate vial containing 300 μl of NaH2PO4 (0.2 g/mL). This solution is then passed through a C18 plus Sep Pak and 0.2 micron Millex filter into the final product vial, to give [11C]D‐methionine. [11C]D‐Methionine was synthesized in >99% ee, 48% decay corrected radiochemical yield, and >99% radiochemical purity. Conclusions We reported a synthesis with excellent enantiomeric purity, >99% ee, of [11C]D‐methionine from a linear D‐ homocysteine precursor, over the previously reported method utilizing a D‐homocysteine thiolactone hydrochloride precursor with 85% ee. This improved synthesis will be applied to murine models of acute bacterial infection, with plans for in‐human studies in the near future. ACKNOWLEDGMENTS We acknowledge NIH R01EB024014, NIH R01EB025985, and DOD W81XWH1810641 and the UCSF Resource Allocation Program for support of this project. RE FER EN CES 1. Gómez, V.; Gispert, J. D.; Amador, V.; Llop, J. New method for routine production of L‐[methyl‐11C]methionine: In loop synthesis. J. Label. Compd. Radiopharm. 2008, 51 (1), 83–86 DOI: https://doi.org/10.1002/jlcr.1483. 2. Neumann, K. D.; Villanueva‐Meyer, J. E.; Mutch, C. A.; Flavell, R. R.; Blecha, J. E.; Kwak, T.; Sriram, R.; VanBrocklin, H. F.; Rosenberg, O. S.; Ohliger, M. A.; et al. Imaging Active Infection in vivo Using D‐Amino Acid Derived PET Radiotracers. Sci. Rep. 2017, 7 (1), 7903 DOI: https://doi.org/10.1038/s41598‐017‐08415‐x.
P os t er C at egor y: Rad i och em i s t ry ‐ 11 C a nd Ot her P os it r o n Em it ter s P-100 | A facile method for the preparation of [11C]cyanide from [11C]methyl iodide Tatsuya Kikuchi1; Ming‐Rong Zhang2; Antony Gee3 1
National Institute for Quantum and Radiological Science and
Technology, Japan; 2 Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan; 3 King's College London, United Kingdom
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Objectives [11C]Cyanide is a useful intermediate for labelling functional groups such as CN, COOH, CONH2, and CH2NH2 in organic compounds. Conventional method for the preparation of [11C]cyanide, however, requires dedicated infrastructure. [11C]Cyanide is generally prepared by heating [11C]CH4 under NH3 gas flow at more than 900°C over a platinum filled column. Furthermore, the starting material, [11C]CH4, is produced by the irradiation of N2/H2 gas or by heating [11C]CO2 under H2 gas flow over nickel. In the previous meeting (ISRS2017), we reported that [11C]cyanide was prepared by the dehydration of [11C]formaldoxime, though the radiochemical yield was insufficient (around 20% from [11C]CO2). Thus, we explored more efficient method to prepare [11C]cyanide without any special equipment and reagents. In this study, we investigated the applicability of hydroxylamine‐O‐sulfonic acid (HOSA) to [11C]cyanide preparation from [11C]CH3I which is widely used for 11C‐labelling (Scheme 1). HOSA has been used as a reagent for the conversion of aldehydes into nitriles. Methods [11C]CH3I (300–400 MBq) was trapped in a 1 mL of trimethylammonium oxide (TMAO, 15 mg) solution in DMF or DMSO and heated for 2 min to prepare [11C]HCHO (at 70°C for DMF solution, at 100°C for DMSO solution). The [11C]HCHO solution (200 μL) was subsequently added to the HOSA solution in the corresponding solvents (200 μL). The reaction conditions are summarized in Table 1. Radiochemical yields from [11C]CH3I were determined by radio‐HPLC analysis of the reaction solution. More than 87% of radioactivity in the injected solution was eluted during the HPLC analysis. Results The results are summarized in Table 1. Higher reaction temperature enhanced the formation of [11C]cyanide (Entry 1–5). The use of DMSO showed better yield of [11C]cyanide compared with DMF (Entry 5, 8). The use of more than 1 equivalent of HOSA based on the amount of TMAO was required to obtain good yields of [11C]cyanide. Consequently, [11C]cyanide was produced in 87% radiochemical yield after 3 min reaction time (Entry 10).
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TABLE 1 Reaction conditions and radiochemical yields (RCYs) Entry
Solvent
HOSA (eq)
Temp (°C)
Reaction Time (min)
RCYs
1
DMF
1
rt
5
12% (n = 1)
2
DMF
1
80
5
17% (n = 1)
3
DMF
2
rt
5
13% (n = 1)
4
DMF
2
80
5
26% (n = 1)
5
DMF
2
100
5
40% (n = 1)
6
DMSO
1
100
5
36% (n = 2)
7
DMSO
2
100
3
43% (n = 2)
8
DMSO
2
100
5
75% (n = 2)
9
DMSO
2
100
10
88% (n = 2)
10
DMSO
2
120
3
87% (n = 1)
Conclusions [11C]Cyanide was efficiently prepared from [11C]CH3I in one‐pot using conventional reagents and lab‐ware. Further optimization of reaction conditions for the production of [11C]cyanide with an automated system is in progress. ACKNOWLEDGEMENT We are grateful to the staff of the Cyclotron Operation Section of our institute for their assistance with radioisotope production. This work was supported in part by JSPS KAKENHI (16K10303).
P os t er C at egor y: Rad i oc h em i s t ry ‐ 11 C a nd Ot her P os it r o n Em it ter s P-101 | Facilitated troubleshooting in (+)‐ [11C]PHNO synthesis by investigation of reagents, byproducts, and intermediates Sarah Pfaff1; Câcile Philippe2; Lukas Nics2; Neydher Berroteran‐Infante1; Katharina Pallitsch3; Christina Rami‐Mark1; Ana Weidenauer4; Ulrich Sauerzopf4; Matthäus Willeit4; Markus Mitterhauser2; Marcus Hacker1; Wolfgang Wadsak2; Verena Pichler2 1
Department of Biomedical Imaging and Image‐guided Therapy, Division
of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; 2
Medical University of Vienna, Austria; 3 Institute of Organic Chemistry,
University of Vienna, Austria; 4 Department of Psychiatry and Psychotherapy, Division of General Psychiatry, Medical University of Vienna, Vienna, Austria
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Objective (+)‐[11C]PHNO (Figure 1) synthesis is quite challenging, as carbon‐11 has a short half‐life of 20 min. The four step synthesis requires harsh conditions under inert atmosphere (Figure 1). Due to those special prerequisites, (+)‐[11C]PHNO synthesis is highly error prone and reveals the highest failure rate within our facility. (+)‐[11C]PHNO is the gold standard for PET‐imaging of dopamine D2/3 receptors in their high affinity state and endogenous dopamine levels and will thus be of increasing importance for clinical studies of schizophrenia in the future. Consequently, efficient and fast troubleshooting after a failed synthesis is pivotal for a continuous workflow within clinical studies. Therefore, the aim of this study was the investigation of the effect of different reagents on the formation of byproducts and intermediates. Methods [11C]CO2 was produced by a GE PETtrace cyclotron 860 (General Electric Medical Systems; Uppsala, Sweden). The precursor (+)‐HNO was provided by ABX (Radeberg, Germany). Small scale reactions and partial runs were performed to simulate characteristic problems and study the resulting byproducts and intermediates (Figure 1). Grignard reactions and formation of the acyl chloride were performed in a loop as published previously.1 All other synthesis steps were conducted in borosilicate glass at ambient temperature. For all synthesis including the formation of the intermediate amide, a precursor solution of (+)‐HNO (1‐2 mg) in THF (400 μL) and Et3N (50 μL) was used. Subsequently, the reaction mixture was transferred to a semi‐preparative HPLC (VWR International GmbH; Vienna, Austria) system using a Phenomenex Luna C18 column (250 × 10 mm, 10 μm; Phenomenex Ltd., Aschaffenburg, Germany) as stationary phase. The mobile phase consisted of 25 mM phosphate buffered saline (PBS) (pH 7.0) and acetonitrile (60/40 v/v) with a flow rate of 5.8 mL/min. The UV signal was measured at 280 nm. Results The most representative signals in the chromatogram are those with retention times between 5 and 7 min. Those signals occurred with a high intensity in all experiments without a reduction by LAH. Hence, the prevalence of those peaks indicates a failed reduction step. Chromatograms showing no signals at this retention time reflect a failed amide formation due to insufficient inertness of previous reaction steps or decomposition of thionyl chloride. Besides, chromatograms showing weak signals in the region of 5‐7 min may originate from insufficient inertness, decomposed Et3N or a failed reduction step.
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Conclusions An assignment of peak patterns in semi‐preparative HPLC and correlation to missing or decomposed reagents could be successfully performed. Consequently, finding the error source will be facilitated and help a convenient performance of clinical studies.
RE FER EN CES 1. Rami‐Mark, C. et al. Reliable set‐up for in‐loop 11C‐carboxylations using Grignard reactions for the preparation of [carbonyl‐11C] WAY‐100635 and [11C]‐(+)‐PHNO. Applied Radiation and Isotopes 82, 75–80 (2013).
P os t er C at egor y: Rad i oc h em i s t ry ‐ 11 C a nd Ot her P os it r o n Em it ter s P-102 | Some aspects on the specific activity of CH3I Bruno Nebeling Synthra GmbH, Hamburg, Germany
Objectives The production of [11C]‐CH3I in high molar activity is mandatory if receptor ligands are going to be labelled with this methylating agent. The gas phase method for the production of [11C]‐CH3I offers the possibility of a significant higher molar activity compared to the classical “wet method” using LiAlH4 in THF to reduce the starting material [11C]‐CO2. Potential sources for cold CH4 in hydrogen are based on the steam reforming pathway and in helium due to the distillation of natural gas. The content of carbon in the nickel catalyst is also an important source if no high purity nickel is used. Nevertheless there is a high interest to know the influence of the different cold carbon sources on the molar activity of [11C]‐CH3I produced via gas phase chemistry. Methods A standard MeIplus synthesizer was used to perform the CH3I synthesis. The used gases were: helium in 7.0 quality and hydrogen in 6.0 quality. Nickel 99.999% with less than 100 ppm of carbon, iodine with 99.999% purity as well Carboxen for trapping the CH4 and Porapak to trap and release the CH3I. The produced CH3I was trapped at −50°C in 500 μl of acetonitrile. The amount of CH3I was analysed via HPLC with a Synthra RadChromplus machine using a Nucleodur Pyramid C‐18 250 × 4 mm 5 μm column.
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Results The mass of CH3I is strongly depending on the purity of the used gases. The amount of CH3I produced was 2 ng +/− 50%. Under these conditions the production of [11C]‐CH3I can easily reach a molar activity of 370000 GBq/μmol or (10000 Ci/μmol). Conclusion The production of high molar activity of [11C]‐CH3I via gas phase chemistry is highly depending on the purity of the used target gas.
Poster Cate gory: Radiochemistry ‐ Radiometals P-103 | Preparation and quality control of ready for injection [64Cu]copper dichloride solution for theranostic applications Miguel Avila‐Rodriguez Universidad Nacional Autonoma de Mexico (UNAM), Mexico
Objectives During the last few years, copper‐64 in its most simple form of copper dichloride [64Cu]CuCl2 has shown great potential for theranostic applications1. This radioisotope can be either produced using a reactor or a cyclotron which can lead to products with varying quality in terms of radiochemical, and chemical purities, in addition to yield and specific activity. However, production of high specific activity 64Cu is best achieved via (p,n) reaction using isotopically enriched 64Ni. After processing of the target material the final product is recovered in a small volume of Cu‐solution in the chemical from of copper chloride. The aim of this work was to formulate a ready for injection solution of [64Cu]CuCl2 and to perform quality control tests before its release for clinical applications. Methods High specific activity 64Cu was produced via proton irradiation of isotopically enriched 64Ni (99.53%, Isoflex), electrodeposited on a gold disk substrate2, with 11 MeV protons (Eclipse HP, Siemens). After bombardment, the target material was dissolved with 2 ml of 10M HCl at 90°C, and radiochemical separation of Ni–Co–Cu was performed using the well‐known chromatography of chloro‐complexes on an anion‐exchange resin column (AG1‐X8, Bio‐Rad)3. The Cu‐fraction was collected in aliquots of 1.5 ml and the 3 most concentrated aliquots were evaporated to complete dryness in a rotary‐evaporator using a 30‐ml pear‐shaped flask. Activity of 64Cu was recovered with 5 ml of physiological
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saline solution (0.9% NaCl) and solution was sterilized by filtration (0.22 μm, Millex‐GV). Quality control tests included appearance (visual inspection), pH (paper strips), radionuclidic purity (HPGe), molar activity (titration method using TETA chelator), membrane filter integrity (BPT, TEMA Sinergie), and bacterial endotoxin (LAL, Endosafe‐PTS). Results Final product was obtained in 5 ml of a clear‐colourless solution with a pH 5.5 ± 0.5. Radionuclidic purity at the time of injection was >99% as determined by gamma spectroscopy with a typical molar activity in the range of 150–700 GBq/μmol (n = 10). Concentration of bacterial endotoxins in the solution was always 104. Besides this 6.76 ppm Cs impurity, MP‐AES measurements established 0.35 ppm (Zn), 0.14 ppm (Fe) and 0.110 ppm (Cu) as the only detectable metal impurities in the final product. Conclusions To our knowledge, the use of the Sr resin enables the highest chemical purity yet reported for 133mBa productions using automatable column extraction
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chromatography. This result has led to the successful preparation of pharmaceutical quality 133mBa that can be used in biomedical applications. R EF E RE N C E S 1. Neirincky R.D. (1977),Int. J. Appl. Radiat. Isot., 28, 323‐325. 2. Van der Meulen N.P. et al.(2010), J. Radioanal. Nucl Chem., 285, 491‐498. 3. Vandenhove H. et al. (2005), J. Environ. Radioact., 81, 255.
Poster Cate gory: Radiochemistry ‐ Radiometals P-125 | Production of [62Zn]citrate and [62Cu] glycine with a modified system
62
Zn/62Cu generator
Zilin Yu1; David Parker2; Antony Gee1; Phil Blower1 1
2
King's College London, UK; School of Physics and Astronomy,
University of Birmingham, UK
Bis(thiosemicarbazonato) complexes of cyclotron generated copper radionuclides such as 64Cu (T1/2 = 12.7 h), 61 Cu (T1/2 = 3.3 h), and 60Cu (T1/2 = 23.7 m) are promising agents for non‐invasive imaging of hypoxia and myocardial/CNS blood flow with positron emission tomography (PET). The rapid pharmacokinetics of these complexes have the potential to allow repeated PET imaging studies in a single session, for example, to determine the effect of an intervention such as carbogen breathing on hypoxic tumours. The short half‐life generator‐produced isotope 62Cu (T1/2 = 9 min) would make this possible. Although the 9.3 h half‐life of the parent radionuclide 62Zn (not commercially available in EU) limits the shelf life of the generator to one day, it is long enough for delivery to national centres. In this study, we developed an optimised 62Zn/62Cu radionuclide generator system building on Fukumura's method. Both [62Zn]Citrate and [62Cu]Glycine could be produced with the same generator system. Production of 1 GBq 62 Zn was accomplished by proton irradiation of copper foils with 29 MeV proton particles at a beam current of 30 μA for 1 h at the University of Birmingham (Birmingham MC40 cyclotron). The generator was prepared according to Fukumura's method with modification. In brief, the target was dissolved in a fresh mixture of concentrated H2O2 (25 mL) and concentrated HCl (25 mL). To isolate 62Zn, the solution was diluted with water
(Cl– final concentration 3 M) and passed through a Chromabond PS‐OH− cartridge. Excess of HCl solution (2 M) was applied to remove metal contaminants. Parent radionuclide 62Zn was eluted with 20 mL of water and loaded on a Sep‐Pak Accell CM plus cartridge. 62Cu was eluted with glycine solution (3 mL, 200 mM). [62Zn]Citrate was produced by flush the CM plus cartridge with 2 mL 4% sodium citrate solution. Breakthrough of 62Zn in [62Cu]glycine solution was evaluated with an HPGe detector. The carrier copper concentration in the final 62Cu elute was measured by ICP‐MS. By replacing the AG1X8 resin columns with Chromabound PS‐OH− anion exchange cartridge, the 62Zn/62Cu generator was ready to elute in 3 hours. The general yield of [62Cu]glycine was 53.93 ± 5.79 % (n = 4, decay corrected) with very low level of 62Zn breakthrough (95% incorporation of 68Ga and 90Y within 15 min. for the DOTA conjugates. Interrogation of the thermodynamics of the radiometal‐chelator coupling by ab initio DFT‐based
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modeling identified a significant thermodynamic advantage for the new PSC macrocyclic for divalent Pb and Cu radionuclides relative to the DOTA and TCMC constructs. Conclusions A new macrocylic tetraaza dicarboxy‐monoamide chelator (PSC) that enables rapid high‐efficiency labeling of divalent Pb and Cu radionuclides for radiopharmaceutical preparation has been evaluated experimentally and via ab initio modeling. Experimental results identify the LTMC as a promising new chelator for this application and ab inito modeling support a thermodynamic advantage vs previously used DOTA and TCMC chelators. ACKNOWLEDGMENTS These studies were supported by the US NIH grants (MKS) 1P50CA174521‐01A1, K25‐CA172218‐01A1, and (MKS/FLJ) R01EB017279‐01A1.
Poster Cate gory: Radiochemistry ‐ Radiometals P-129 | Evaluation of radiation dose on 99Mo absorption of AG1‐×8 resin Jixin Liang; Yijia Shen; Xueqin Xiang; Yuxuan Wu; Ningwen Yu Department of Isotope, China Institute of Atomic Energy, China
Objectives Currently, 99Mo plays a very important role in nuclear medicine. 99mTc, the daughter of 99Mo, is widely used for clinical imaging procedures. Medical 99Mo is mainly extracted from the fission products of 235U, which is usually involved in precipitation, ion exchange chromatography. During the purification process, due to the high dose from fission products, radiolysis of resin probably happens and thus 99Mo adsorption of resin will change. In our study, AG1‐×8 resin is used for 99Mo purification from impurities. The aim of this work is to evaluate the influence of γ radiation dose on AG1‐×8 anion resin on adsorption of 99Mo. Methods AG1‐×8 anion resin was irradiated with 60Co γ source at different γ radiation doses of 37.5 kGy, 275 kGy, and 825 kGy. The surface structure of the irradiated AG1‐×8 resin samples was analyzed using scanning electron microscope (SEM) and was compared to that of non‐irradiated AG1‐×8 resin. The irradiated resin
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was completely dried at 60°C. To 0.5 gram dried resin, add 5.0 mL solution containing Mo (99Mo as radiotracer). The mixture was incubated for 30 min at 25°C. After filtration, radioactivity of 99Mo in the original solution and the filtrate was measured by HP Ge gamma detector respectively. The adsorption capacity of 99Mo for per gram resin was determined by calculating the ratio of 99 Mo radioactivity on the resin to that in the original solution. Results and discussion SEM analysis showed that no difference was observed between the surface of the irradiated resin and that of non‐irradiated resin. Furthermore, for the surface of any irradiated resin, no dilapidation was found. For irradiated resin at 37.5 kGy and 275 kGy dose, the adsorption capacity of 99Mo showed no difference compared to that of non‐irradiated resin in 0.01 mol/L and 0.1 mol/L HNO3, NaOH, (NH4)2CO3, NH4OH, and (NH4)2SO4 solution as media. However, absorption of 99 Mo on AG1‐×8 resin irradiated at 825 kGy decreased significantly compared to that of non‐irradiated AG1‐×8 resin in the mentioned media, indicating that radiation dose should be taken into account while using AG1‐×8 anion exchange chromatography for fission 99Mo purification. Conclusion From the experimental results, no dilapidation happened to the surface of the irradiated resin at 37.5 kGy, 275 kGy, and 825 kGy. For comparatively low dose level (37.5 and 275 kGy), the radiation dose had no significant influence on adsorption of 99Mo of the AG1‐×8 resin. However, the 99 Mo adsorption capacity of the irradiated resin at high dose (825 kGy) decreased significantly. This work indicated that radiation dose should be taken into account while using AG1‐×8 resin for fission 99Mo purification, which is expected to provide data for optimization of fission 99Mo production process. ACKNOWLEDGEMENT This work was financially supported by the Ministry of Science and Technology of PRC and China National Nuclear Corporation. RE FER EN CES 1. Seung‐Kon Lee, Gerd J. Beyer, JunSig Lee, Development of industrial‐scale fission 99Mo production process using low enriched uranium target [J], Nuclear Engineering and Technology, 2016, 48:613‐623.2. 2. Dadachova K, Riviere K, Anderson P. Improved processes of 99 Mo production [J]. Journal of Radioanalytical and Nuclear Chemistry. 1999, 240(03):935–938.
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Poster Cate gory: Radiochemistry ‐ Radiometals P-130 | Technetium complexes of 2‐hydrazinopyridine and hydrazinonicotinamide (HYNIC)‐conjugated peptides. Insights from LC‐MS and electrophoresis studies Justyna Pijarowska‐Kruszyna; Antoni Jaroń; Monika Orzełowska; Michał Maurin; Renata Mikolajczak; Piotr Garnuszek National Center for Nuclear Research, Radioisotope Center POLATOM, Poland
Objectives Hydrazinonicotinamide (HYNIC) with ethylenediaminediacetic acid (EDDA) as co‐ligand is a very efficient chelating system for technetium‐99m labelling of biomolecules. The nature of Tc‐EDDA/HYNIC complexes was investigated in several published studies.1,2 However, the full characterization of technetium coordination sphere still remains a point of discussion. To understand the chemistry of this unique metal‐ligand system, we have prepared a model complex of 2‐hydrazinopyridine (HYPY) and two HYNIC‐derivatized peptides with technetium‐99m as well as with long lived technetium‐99. Methods In this study the 2‐hydrazinopyridine (HYPY) and the peptides: cyclic somatostatin analog Tyr3‐Octreotide (HYNIC‐TOC) and small linear PSMA analog (HYNIC‐ PSMA) were used. Their complexes with technetium‐99 were synthesized via tricine/EDDA co‐ligand exchange reaction in a micromolar scale using 2:1 molar ratio of 99 Tc to HYNIC‐peptides or HYPY with large excess of co‐ligands at the standardized conditions for labelling.3 The intermediate complexes with tricine as co‐ligand were also synthesized. The radioactive complexes with technetium‐99m served as standard solutions. They were characterized by HPLC and LC‐MS methods using electrospray ionization mass spectroscopy with positive ionization mode. For 99mTc‐complexes, the isoelectric point (pI) was measured using isoelectric focusing (IEF) electrophoresis technique. Radiolabelled peptides were spotted on polyacrylamide gels and electrophoresis was performed by increasing voltage gradually from 100 to 400V. The retardation factors of radioactive complexes were compared with the retardation factor of IEF markers to calculate pI of each complex. In paper electrophoresis of 99mTc‐EDDA/HYNIC‐peptide‐complexes, the stationary phase was Whatman 1 chromatography paper
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and as electrolyte the sodium perchlorate buffer at pH close to pI value was used. Results The HPLC analysis confirmed the identity of complexes prepared both at the tracer (99mTc) and at the macroscopic (99Tc) levels. HPLC chromatograms obtained with UV detection revealed multiple peaks. These could be the result of isomerism in the technetium coordination sphere. For 99 Tc‐EDDA/HYNIC‐TOC and HYPY complexes, these peaks had the same mass of ions found in LC‐MS at m/z 808.7 ([M+2H]2+) and at 556.1 ([M+H]+), which corresponded to the complexes containing two EDDA molecules. For the 99Tc‐EDDA/HYNIC‐PSMA complex, the expected mass of molecular ions at m/z 613.7 ([M+2H]2+), indicating the presence of two EDDA molecules, was also found. However, a small peak with a mass at m/z 525.6 ([M+2H]2+ corresponding to a mono‐EDDA complex was also seen. The presence of labelled species containing mixed tricine/EDDA ternary complex and an oxo or halide group in complexes was excluded. Similarly, for 99Tc‐complexes formed using tricine as co‐ligand, LC‐MS analysis of multiple peaks gave the same mass of ions at m/z 722.2 ([M+2H]2+) for 99Tc‐tricine/HYNIC‐ TOC, 527.1 ([M+2H]2+) for 99Tc‐tricine/HYNIC‐PSMA and 383.1 ([M+H]+) for 99Tc‐tricine/HYPY. These masses corresponded to the mono‐tricine complexes. In the presence of co‐ligands technetium atom binds to HYNIC‐ peptides or HYPY with the displacement of five hydrogen atoms, implicating the technetium (V) oxidation state. The low value of pI < 3.5 determined for 99mTc‐EDDA/ HYNIC‐peptide complexes also may indicate the presence of two EDDA co‐ligand molecules with carboxylic group not coordinated to technetium, while pI of about 8.0 for 99m Tc‐tricine/HYNIC‐peptide complexes indicates mono‐ tricine complex formation. In paper electrophoresis, 99m Tc‐EDDA/HYNIC‐peptide complexes migrated toward anode, the same as pertechnetate ion, confirming that HYNIC‐bioconjugates form negatively charged complexes with technetium‐99 when EDDA is used as co‐ligand. Conclusions The LC‐MS and electrophoresis results confirmed the identity and the number of co‐ligand molecules involved in Tc‐HYNIC‐complexes, thus having an important impact on the structural characterization of these complexes. RE FER EN CES 1. King R.C. and et al (2007) Dalton Trans., 43, 4998‐5007. 2. Bashir‐Uddin Surfraz M. and et al (2009) J Inorg Biochem, 103, 971‐977. 3. von Guggenberg E. and et al. (2003) J Labell Compd Radiopharm, 46, 307‐318.
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Poster Cate gory: Radiochemistry ‐ Radiometals P-131 | A novel FAP‐inhibitor containing squaric acid coupled DOTA: Synthesis and preliminary evaluation Elisabeth Eppard1; Lukas Greifenstein2; Euy Sung Moon2; Tilmann Grus2; Vasko Kramer3; Frank Roesch4 1
PositronPharma, Chile; 2 Johannes Gutenberg University Mainz, Institute
of Nuclear Chemistry, Germany; 3 Positronpharma SA, Chile; 4 Johannes Gutenberg University, Germany
Objectives The membrane bound serine protease fibroblast activation protein (FAP) is overexpressed in cancer‐associated fibroblasts. It is involved in a number of tumour– promoting metabolic processes like matrix remodelling, angiogenesis, chemotherapy resistance, and immunosuppression. While FAP shows low expression in most normal organs, cancer‐associated fibroblasts, representing a subpopulation of tumour stromal cells, overexpressing FAP are associated with poor prognosis in cancer patients. As the tumour stroma accounts for a large part of the tumour mass, this subpopulation represents an attractive target for the delivery of diagnostic as well as therapeutic compounds. Consequently, recent developments on this target showed promising results in preclinical and a few clinical set ups with FAP‐inhibitors for positron‐emission tomography (PET). In the presented work, a new FAPI variation of the 4,4‐difluoropyrrolidine‐quinoline motif for PET and therapy based on the work from Lindner et al1 was synthesized utilizing squaric acid as linker between the chelator and the biological active moiety and preliminary evaluated with gallium‐68. Methods The pyrrolidine unit (S)‐4,4‐difluoro‐1‐glycylpyrrolidine‐ 2‐carbonitrile was prepared by an 8‐step synthesis starting from N‐Boc‐trans‐4‐hydroxy‐L‐proline methyl ester.2 The quinoline based derivate 6‐(4‐amino‐butoxy) quinoline‐4‐carboxylic acid could be synthesized by a 3‐step synthesis from 6‐methoxyquinoline‐4‐carboxylic acid. DO3A‐tBu‐N‐(2‐aminoethyl)ethanamide was selectively bound by amidation with squaric acid at pH = 7 and subsequently purified by HPLC (Merck Hitachi LaChrom). The selective coupling of DOTA‐SA to the new FAPI derivate was performed by asymmetric amidation at pH = 9. The tert‐butyl protecting groups were removed with TFA and the crude product was purified by HPLC. Radiolabelling of DOTA‐SA‐FAPI
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with gallium‐68 was performed manually utilizing ethanol post‐processed 68Ga‐eluate from a 2‐year‐old 68Ge/ 68 Ga‐generator (ITG, Garching). 300 μl eluate and 300 μl 1 M ammonium acetate buffer were mixed with varying amount (10‐40 μg) of DOTA‐SA‐FAPI and heated in a thermo shaker at different temperatures (70‐95°C). Additionally, the process was automated using a IBA Synthera. C18 purification was performed using standard protocol. RadioTLC as well as radioHPLC were used for determination of radiochemical purity. Stability studies against transmetallation, transchelation as well as in human serum, ethanol and saline were performed. Results A new FAPI moiety (S)‐6‐(4‐aminobutoxy)‐N‐(2‐(2‐ cyano‐4,4‐difluoropyrrolidin‐1‐yl)‐2‐oxoethyl)‐quinoline‐ 4‐carboxamide could be isolated via an amide coupling of the pyrrolidine and the quinoline units. The bifunctional site with the free amine on the pyrrolidine‐quinoline motif was coupled with DOTA‐SA. Therefore, a new chelator‐FAPI‐compound DOTA‐SA‐FAPI [(S)‐2,2′,2″‐ (10‐(2‐((2‐((2‐((4‐((4‐((2‐(2‐cyano‐4,4‐difluoropyrrolidin‐ 1‐yl)‐2‐oxoethyl)carbamo‐yl)quinolin‐6‐yl)oxy)butyl) amino)‐3,4‐dioxocyclobut‐1‐en‐1‐yl)amino)ethyl)amino)‐ 2‐oxoethyl)‐1,4,7,10‐tetraazacyclododecane‐1,4,7‐triyl) triacetic acid] for radiolabelling with different radiometals could be synthesized. Subsequent semi‐preparative HPLC obtained the final product purity suitable for radiometal labelling. Radiolabelling kinetics with varying amounts of chelator as well as at different temperatures were investigated as well as subsequent cartridge‐based solid‐phase‐ extraction (C‐18) resulting in a radiochemical purity of the final tracers of ≥98%. Stability studies for transmetallation and transchelation [68Ga]Ga‐DOTA‐SA‐FAPI were performed covering a period of 2 h and confirmed high stability in all experiments. Radiochemical purity could be analyzed effectively using radioHPLC and radioTLC. Also the automated process leads to a final product with high radiochemical purity and good radioactivity yields. Additionally, a first labelling using generator derived scandium‐44 could be performed but with low radiochemical yields. Further investigation here is needed. Conclusion The new FAPI‐compound DOTA‐SA‐FAPI was successfully evaluated in terms of radiolabelling kinetics as well as in vitro stability with gallium‐68 as radiometal. Determination on in vitro affinity towards FAP and selectivity over PREP, DPP4 and DPP8 are currently underway and further studies, e.g. cell studies, small animal imaging, are planned to evaluate its potential as PET imaging agent.
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R EF E RE N C E S 1. Lindner, T., Loktev, A., Altmann, A., Giesel, F., Kratochwil, C., Debus, J., Jäger, D., Mier, W., Haberkorn, U., Development of quinoline‐based theranostic ligands for the targeting of fibroblast activation protein. J. Nucl. Med. 59, 1415‐1422 (2018). 2. Jansen, K., Heirbaut, L., Verkerk, R., Cheng, JD., Joossens, J., Cos, P., Maes, L., Lambeir, AM., De Meester, I., Augustyns, K., Van den Veken, P., Extended structure‐activity relationship and pharmacokinetic investigation of (4‐quinolinoyl)glycyl‐2‐ cyanopyrrolidine inhibitors of fibroblast activation protein (FAP). J Med Chem. 57(7), 3053‐74 (2014).
Poster Cate gory: Radiochemistry ‐ Radiometals P-132 | HPLC for determination of unbound gallium‐68 in radiopharmaceuticals: Pitfalls and solutions Anton Larenkov; Alesya Maruk; Galina Kodina State Research Center ‐ Burnasyan Federal Medical Biophysical Center, Russian Federation
Objectives Determination of radiochemical purity (RCP) of 68Ga‐ radiopharmaceuticals (RPs) is an extremely important part of QC in routine clinical practice. Knowing the exact value of content of every radiochemical impurity is very important during R&D of 68Ga‐RPs as well. It was previously shown that HPLC results do not always match TLC results, especially for unbound 68Ga content.1 This uncertainty comes from nonspecific sorption of unbound 68Ga on C18 phase. The aim of this study was to fix the weakness of the HPLC analysis procedure, since in some cases it can be difficult to replace. Methods 68 Ge/68Ga generator (Cyclotron Ltd, Russia) was used. All chemicals and solvents were of high‐purity or pharmaceutical grade and were purchased from Sigma‐ Aldrich or Panreac. Radiopharmaceutical precursors were purchased from ABX. Chelators were purchased from CheMatech, ABX and TRC Canada. iTLC‐SG strips by Thermo Fisher Scientific were used. Different radio‐TLC systems were used to determine all 68Ga species content. PET‐MiniGita (Raytest) scanner was used. For HPLC analysis Knauer Smartline chromatograph with fLumo (Berthold) radiodetection system was used. The mobile phase for HPLC consisted of 0.1% TFA solutions in water and acetonitrile in different ratios in accordance with 9th Ph. Eur. recommendations.
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Different HPLC C18 columns were used (Merck, Phenomenex, ACE). Results It was found that, in pH range from 3 to 6, there is a significant capture of the 68Ga ion forms on the reversed phase of the HPLC column (e.g. 60% capture with pH 4.6). The value of the capture also depends on the nature and concentration of buffer agent in the preparation. The nature of this phenomenon is a subject of pure radiochemistry. New data shedding light on this effect will be presented. In order to avoid this capture during HPLC analysis, a new procedure of sample processing and analysis was developed. The procedure involves usage of chelators in order to prevent 68Ga sorption on the column. For this purpose, DTPA, DOTA, NOTA, and HBED were evaluated. The details of their influence on the course of analysis will be presented. Conclusions In a number of cases, the results of HPLC analysis of 68 Ga‐cojugates performed according to 9th Ph. Eur. recommendations did not reflect the real unbound 68 Ga content in radiopharmaceutical preparations. It was highly probable that the same effect can occur when analyzing other metal‐based RPs (such 111In, 177 Lu, etc.). To avoid this effect, new procedure of HPLC analysis was designed.
RE FER EN CE 1. Larenkov AA, Maruk AYa, Kodina GE. Intricacies of the determination of the radiochemical purity of 68Ga preparations: possibility of sorption of ionic 68Ga species on reversed‐phase columns. Radiochemistry 2018;60(6):625–33.
P os t er C at egor y: Rad i oc h em i s t ry ‐ Radiometals P-133 | New phosphonic acids as components of bone seeking radiopharmaceuticals Galina Tsebrikova1; Vladimir Baulin1,2; Valery Ragulin2; Vitaly Solov'ev1; Alesya Maruk1,3; Elena Lyamtseva3; Anna Malysheva3; Anton Larenkov3; Maria Zhukova3; Aleksandr Lunev3; Olga Klementyeva3; Galina Kodina3; Yujin Wang4; Aslan Tsivadze1 1
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian
Federation; 2 Institute of Physiologically Active Compounds, Chernogolovka, Russia Severny proezd, Russian Federation; 3 Burnasyan Federal Medical Biophysical Center, Russian Federation; 4 Harbin Institute of Technology, China
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Objectives Modern radiopharmaceuticals are complexes of radiometals with organic ligands. The ligand selectively binds and stabilizes radionuclide and delivers it to the target organs and tissues. Phosphonic acids have a high affinity for the bone matrix; therefore, they are promising compounds for developing bone seeking radiopharmaceuticals. In the present work, new phosphonic acids were synthesized. Physico‐chemical and biological properties of these acids and their complexes with 68Ga, 153 Sm, and 188Re were studied. Methods New aminobisphosphonic acids I‐V were obtained by addition of H3PO3 to the corresponding nitriles. Compound I is a salicylic acid derivative. Compound II is a derivative of 2‐oxyphenylphosphonic acid. Acids III‐V are analogs of the widely used organic ligand which is a part of the [153Sm]samarium oxabifore radiopharmaceutical. The known methods of synthesis of cyclen‐containing phosphonic acids VIa‐d with the side chain of different length and asymmetrically substituted with methylenepyridine fragment were improved, and new approaches were developed. Complexation of Ga3+ and Sm3+ cations with the obtained compounds was studied by 1Н, 13С, and 31Р NMR and potentiometry for the first time. The yields of labeling reactions with 68Ga, 153 Sm, and 188Re were estimated using radio‐TLC method.
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The biodistribution of labeled compounds was evaluated by direct radiometry. Results and Discussion Phosphonic acids I‐VI with the well‐known coordination fragments 2‐oxyphenylphosphonic (I), salicylic (II), aminobisphosphonic acids (III‐V), and cyclen (VI) were synthesized through a short and efficient synthesis. Protonation constants of III, V, and VIa in water were determined using potentiometry. Species distribution diagrams of the deprotonated forms of acids as a function of pH were plotted. The stability constant log KML of Ga3+ complex with III is equal to 16.2. The stability constant of the Ga3+ complex with the fully deprotonated ligand VIa log KML = 27.8 is higher than the corresponding constant of the Ga3+complex with DOTA, the ligand most used in radiopharmacy (log KML = 21.3). It is also higher than the constant of the Ga3+ complex with plasma protein transferrin (log KML = 20.3), which makes the VIa a promising ligand for the use in radiopharmacy. Interaction of Ga3+ and Sm3+ cations with III was studied using 1Н, 13 С, and 31Р NMR in D2O. The results indicate that only two α‐aminophosphonic groups of III participate in 1:1 complex formation with Sm3+. The mixture of several Ga3+ complexes with different protonation states and different interactions between metal cation and donor atoms was found. The effect of temperature,
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reaction time, pH and buffer solution on the yield of the 68 Ga complexes with III, IV and VI was studied. Based on preliminary evaluation of biodistribution in vivo, it was found that [153Sm]Sm‐III, [68Ga]Ga‐III, [68Ga]Ga‐ VIa, [68Ga]Ga‐VId, and [188Re]Re‐V show moderate bone uptake and increased accumulation in bone fracture sites, which were used as models of bone metastasis. ACKNOWLEDGMENTS This work was financially supported by the Russian Foundation for Basic Research (project 18‐33‐00685 and 19‐03‐00262). The study of physico‐chemical and biological properties of synthesized compounds was financially supported by Russian Scientific Foundation (project 19‐13‐00294).
Poster Cate gory: Radiochemistry ‐ Radiometals P-134 | Zirconium‐89 solutions: Preparation, formulation, analysis, and comparison of applicability for radiopharmaceutical purposes Anton Larenkov; Viktor Bubenschikov; Artur Makichyan; Galina Kodina State Research Center, Burnasyan Federal Medical Biophysical Center, Russian Federation
Objectives The aim of this study is to develop a handy procedure for preparation of zirconium‐89 in the form of an oxalate‐free physiologically acceptable solution suitable for radiolabeling. Another objective was to design an adequate quality control procedure and to compare this formulation with other frequently used ones. Methods All chemicals and solvents were of high‐purity or pharmaceutical grade and were purchased from Sigma‐Aldrich or Panreac. Quality control was carried out with TLC chromatography (iTLC‐SG strips, different eluents; PET‐MiniGita radio‐TLC scanner). Dowex1, Chelex‐100 (Sigma‐Aldridge), ZR (Triskem), and Chromafix‐HCO3 (Macherey‐Nagel) resins were used. [89Zr]ZrCl4 in 5 M HCl was purchased from Cyclotron Ltd (Russia). Results A handy procedure of production of [89Zr]zirconium oxalate isotonic (0.115 M oxalate) solution suitable for radiolabeling was developed previously.1 Since ambiguous
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interpretation of oxalate toxicity and there is a possibility that it can interfere with the labeling process, we modified the procedure the following way. A new oxalate‐free method using sodium citrate solution was developed. Using Chelex‐100 resin allows obtaining 89Zr in 0.1‐1.0 M sodium citrate solutions with high yield (≥95%). The solutions are stable for at least 10 days, pH 5‐7. The solutions were successfully used for obtaining 89Zr‐labeled DFO‐conjugates with high radiochemical purity. Our data indicate that citrate anion forms a weaker complex with [89Zr]zirconium than oxalate. Therefore, we assume, citrate will interfere with the labeling process less. It was found that, in some cases, the previously reported method of analysis does not reflect the true content of [89Zr]zirconium in unbound ‘active’ form. An adequate method of analysis was designed. We suggest using the method iTLC/CH3OH‐H2O (1:1), 4% TFA (v/v). Using this method, we carried out the comparison of oxalate‐free method with frequently used ones. Experimental results will be presented in detail. Conclusion A handy procedure for preparation of zirconium‐89 in the form of oxalate‐free physiologically acceptable solution suitable for radiolabeling was developed. An adequate quality control procedure for this new formulation was designed. During this study, new features of [89Zr] zirconium chromatographic behavior were observed. These new data are very important for understanding zirconium‐89 radiopharmaceutical chemistry. ACKNOWLEDGMENTS The work was financially supported by Ministry of Education and Science of the Russian Federation – State Contract No. 14.N08.11.0162. RE FER EN CE 1. Larenkov A, Bubenschikov V, Makichyan A, Kodina G. Preparation of 89Zr‐oxalate isotonic solution for nuclear medicine. Eur J Nucl Med Mol Imaging 2018;45:Suppl 1:S666
P os t er C at egor y: Rad i oc h em i s t ry ‐ Radiometals P-135 | Investigations on the mechanism of simultaneous photochemical conjugation and radiolabelling of proteins with modified arylazides Melanie Gut1; Larissa Eichenberger2; Jason Holland1 1
Department of Chemistry, University of Zürich, Switzerland; 2 University
of Zürich, Switzerland
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Objectives Classical methods to radiolabel antibodies typically require multi‐step procedures involving functionalisation of the protein with a chelate, purification, and subsequent radiolabelling. Photochemical conjugation is a well‐established method to functionalise biomolecules. Photoreactive groups like benzophenones, diazirines and arylazides have been used extensively in the field of photoaffinity labelling. Recent work in our group combined photochemical conjugation with radiochemistry to develop an unprecedented one‐pot approach for the synthesis of radiolabelled antibodies (and other proteins) in 99%. After adjusting the pH, an aliquot of pre‐purified trastuzumab was added to give an initial chelate‐to‐antibody ratio of around 10‐to‐1 at the start of
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the photochemical conjugation step. The reaction mixture was irradiated with light‐emitting diode (LED, 100% intensity, 365 nm) for 99%. Good results have been achieved using both C8 and C18 SPE purification, approximately 15‐25% product loss on the cartridge, with a radiochemical purity of >98%. Product loss through transfers and washing was significantly reduced through the use of 0.9% saline solution rather than water. Finally, excellent radiochemical stability was established at 24 hours (>95% RCP) and at 48 hours (>90%) with product 1. This was achieved through the use of ethanol (10%) and either ascorbic acid or L‐methionine.
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Conclusion To date, an optimised radiochemistry procedure has facilitated excellent radiochemical yields of >99%. An optimised purification process has been developed with only 15‐25% transfer losses yielding the product 1 in >98% radiochemical purity. Final reformulation with radioprotectants, ascorbic acid, or L‐methionine allow for extended radiostability of >90% at 48 hours. With this robust method, automation can be achieved and further preclinical data reliably acquired.
Poster Cate gory: Radiochemistry ‐ Radiometals P-152 | Pre‐targeted glucose metabolism imaging of murine tumors with technetium‐ 99m labelled dibenzocyclooctyne derivative Jin Ding1,2,3; Taiwei Chu1,2,3 1
Clarity Pharmaceuticals, Australia; 2 University of Melbourne, Australia;
3
ANSTO, Australia
Objectives FDG‐PET imaging technology is advanced, effective, and expensive, which is special in the field of radiotherapy but not popular in most areas.1 For more than a decade, many researchers have been trying to replace the FDG‐PET technology with the widely used and easy‐to‐use 99mTc‐SPECT technology, by the design and synthesis of glucose metabolic imaging agents. However, they failed to achieve this goal owing to the chemical complexity of 99mTc and the lack of maintaining the physiological activity of diagnostic compounds.2 Since the poor biological evaluation of glucose metabolic imaging agents, a pretargeting method was investigated in this study. Methods [99mTc(CO)3‐C7]+ (100 μL, 0.25 MBq, 2.5 × 10−4) and (100 μL, 0.25 MBq, [99mTc(CO)3‐C7‐GlucN3]+ 2.5 × 10−4) were injected into each mouse bearing S180
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(weighing 20‐25 g) via the tail vein as potential contrast agents for conventional tumor imaging, respectively. In addition, in the blocking experiment, 10% glucose solution was injected into mice with GlucN3. While in the pre‐targeting study, each mouse was injected with GlucN3 (200 μg), and then injected with [99mTc(CO)3‐C7]+ (100 μL, 0.25 MBq, 2.5 × 10−4) after 1 h/3 h/6 h to conduct SPAAC reaction in vivo. Results The biodistribution study was divided into two parts. In the first part, 1 h, 3 h, and 6 h were taken as pre‐target time, 0.5, 1, 2, and 4 h were taken as target‐seeking time for 12 groups of crossover experiments. The optimal tumor/blood ratio and tumor/muscle ratios were obtained at the pre‐target time of 6 h and the target‐ seeking time of 2 h (tumor/blood ratio = 2.95 ± 0.03, tumor/muscle ratio = 6.37 ± 1.20). In the second part, as shown in Figure 1, with the increase of target‐seeking time, the tumor uptake, tumor/blood, and tumor/muscle values in pre‐target strategy increase gradually, while there were no significant changes in the two control groups and the blocking experimental group. This led to the tumor uptake, tumor/blood and tumor/muscle values in pre‐target strategy being several times higher than the other three experiments when the target‐seeking time reached more than 1 h. It was proved that the in vivo imaging agent actor is the pre‐target process instead [99mTc(CO)3‐C7]+ or [99mTc(CO)3‐C7‐GlucN3]+, and the physiological behavior of the precursor GlucN3 is similar to that of glucose. Conclusions The pre‐targeting strategy protects the biological activity of glucose molecules, thus providing an innovative method for the development of 99mTc‐SPECT glucose metabolic imaging agents for tumors.
RE FER EN CES 1. Kelloff, G.J., et al., ProxG‐PET imaging for cancer patient management and oncologic drug development. Clinical Cancer Research An Official Journal of the American Association for Cancer Research, 2005.11(8): p. 2785.
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Figure 1 (A) crossover experiment of biodistribution (tumor uptake (a), tumor/blood (b), tumor/muscle (c)) between pre‐target time and in vivo target‐seeking time. (B) Comparison of biodistribution (tumor uptake (a), tumor/blood (b), tumor/muscle (c)) among blank control ([99mTc(CO)3‐C7]+), conventional control ([99mTc(CO)3‐C7‐GlucN3]+), blacking control and pretargeting strategy (each mouse was injected with GlucN3, 6 h later with [99mTc(CO)3‐C7]+)
2. Bowen, M.L. and Orvig C, 99m‐Technetium carbohydrate conjugates as potential agents in molecular imaging. Chemical Communications, 2008.40(41): p. 5077‐5091.
Poster Cate gory: Radiochemistry ‐ Radiometals P-153 | Abstract withdrawn
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P os t er C at egor y: Rad i oc h em i s t ry ‐ Other Radionuclides P-154 | In vivo imaging of diesel exhaust particulates in mice via efficient radioactive iodine labeling of polycyclic aromatic hydrocarbon assemblies Ha Eun Shim; Chang Heon Lee; Lee Song; Jongho Jeon Korea Atomic Energy Research Institute, Republic of Korea
Introduction Diesel exhaust particulates (DEP) from diesel‐fueled engines are of severe concern because of their profound adverse effects on human health and the environment. A lot of toxicological studies have reported that exposure to diesel exhaust results in various respiratory diseases. In addition, the inhalation of diesel exhaust may also have various toxic effects on the extrapulmonary organs, including vascular dysfunction and neurological disorders. To better understand the human health risks associated with the exposure to toxic substances, it is essential to characterize the interactions and behavior of such substances in living subjects. In this study, we applied a convenient and efficient radioisotope‐labeling method to conduct a bioimaging study and quantify the biological uptake and accumulation of DEP in tissues. Methods Electrophilic substitution of 2 was achieved using [125I] NaI in the presence of chloramine‐T as an oxidant at room temperature to give the desired product, [125I]1 (Figure a). After purification of the crude mixture by preparative HPLC, [125I]1 was obtained with a radiochemical yield of 32% ± 4% (n = 3). To prepare a radiolabeled DEP suspension in water, the standard DEP reference material and [125I]1 were dissolved separately in dichloromethane (DCM). These solutions were mixed together at room temperature and then DCM was removed by blowing nitrogen gas at room temperature. Distilled water was added to the dried hydrocarbon mixture, which was then ultrasonicated at
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an elevated temperature to obtain the radioactive iodine‐incorporated DEP suspension in water. Next, we administrated the radiolabeled DEP (3.7 MBq per mouse) via intratracheal instillation or oral administration to carry out SPECT/CT imaging and biodistribution study. Results Whole‐body SPECT images clearly revealed that 125I‐DEP was primarily accumulated in the lungs after intratracheal instillation (Figure b). Moreover, a strong signal was still observed in the respiratory system after 48 h, whereas most of the signals in the other organs, including the intestines, diminished significantly. Biodistribution results also showed that high levels of 125 I‐DEP were detected in the lungs 0.5 h post administration, which then slowly decreased, with approximately 61% of the initial uptake value retained after 48 h (Figure c). In addition, DEP was also observed in the liver and intestines, suggesting that some DEP underwent hepatobiliary clearance. On the other hand, orally administered DEP had little effect on lung accumulation, and 125 I‐DEP was excreted within 2 days, with no significant uptake in the extraintestinal organs such as the lungs, liver, and spleen (Figure d). These results indicate that the accumulation of 125I‐DEP in the lungs mainly results from uptake into the respiratory system, not from translocation from the gastrointestinal tract. These observations highlight the value of investigating DEP accumulation via
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different administration routes to analyze the in vivo behavior of DEP. Conclusion High uptake and slow clearance pattern of DEP observed from molecular imaging and biodistribution studies may underlie its severe toxicity in the respiratory organs. Furthermore, we expect that our method is not limited to DEP but can be extended to the assessment of other polyaromatic‐hydrocarbon based environmentally toxic particulates and synthetic materials.
P os t er C at egor y: Rad i och em i s t ry ‐ Other Radionuclides P-155 | Synthesis of 4‐(4‐[I‐123]iodophenyl) piracetam, a potential SPECT agent for Parkinson's disease Murthy Akula1; David Blevins2; George Kabalka1; Dustin Osborne1 1
University of Tennessee Medical Center, USA; 2 The University of
Tennessee, GSM, USA
Objective Racetams having N‐substituted pyrrolidin‐2‐one as a core structure have been used for cognitive disorders such as
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dementia, vertigo, and dyslexia.1 Recently, a 99mTc complex of piracetam, 1, has been reported2 as a brain imaging agent. 4‐Phenylpiracetam, 2, is an aromatic analogue which is more lipophilic and used in the treatment of PD. We wish to report the synthesis of 4‐(4‐[123I]iodophenyl)piracetam, 7, as a potential SPECT agent for brain evaluation. Methods The requisite stannyl precursor 6 was prepared from ethyl 4‐bromocinnamate, 3, in four steps in an overall yield of 40 % as shown in the scheme below. Michael addition of nitromethane to cinnamic acid ester 3 using K2CO3 as base and tetrabutylammonium carbonate as phase transfer catalyst in toluene at ambient temperature afforded the nitro ester 4. Reductive cyclization of nitro ester 4 using NiCl2 and NaBH4 in methanol followed by N‐alkylation with ethyl bromoacetate furnished the ester 5. Palladium catalyzed debromostannylation of 5 resulted in the key stannane precursor 6 for radio iodination. Results To no‐carrier‐added Na123I (0.96 mCi in 0.1% aqueous NaOH) in 2 mL Wheaton vial with a stirring bar was added the tin precursor 6 (100 mL of 4.8 × 10−2 M solution in H2O:THF = 1:1). Peracetic acid (100 mL; 0.3% THF was added and the resulting reaction mixture was stirred at room temperature for 10 min. The labeled product was passed through a C18 cartridge and was eluted with ethanol (1.0 mL). The ethanolic solution of an intermediate ester heated with conc. NH4OH at 70oC for 12 min to obtain the compound 7. The crude product was purified by HPLC to get 4‐(4‐[123I]iodophenyl)piracetam, 7 (0.27 mCi), in 28% radiochemical yield (n = 3). Conclusions A novel radio‐tracer 4‐(4‐[123I]iodophenyl)piracetam, 7, a potential SPECT imaging agent for PD has been
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successfully synthesized in two steps from tin precursor 6. The radiochemical yield and purity were found to be 28% and 95% respectively. The total reaction time was 40 min. Animal studies are currently underway. ACKNOWLEDGEMENTS We wish to acknowledge the Molecular Imaging and Translational Research Program and University Health Systems, Knoxville for the support of this research.
RE FER EN CES 1. Ahmed A, Oswald R. J. Med. Chem. 2010, 33, 2197‐2203. 2. Amin AM, Sanad MH, Abd‐Elhaliem SM. Radiochemistry 2008, 55, 624‐628.
P os t er C at egor y: Rad i oc h em i s t ry ‐ Other Radionuclides P-156 | Radioiodinated EIPBA for PR targeting with enhanced nucleus uptake via phenylboronic acid conjugation Fei Gao1,2; Rongqiang Zhuang1; Jindian Li1; Zhi Guo2; Xianzhong Zhang2 1
State Key Laboratory of Molecular Vaccinology and Molecular
Diagnostics and Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, China; 2 Xiamen University, China
Objectives The expression of progesterone receptor (PR) located in the nucleus closely related to the prognosis of breast cancer. Thus, a novel 131I‐radiolabeled probe with
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aromatic boronate motif was designed to target PR‐ positive breast cancer via enhanced nucleus uptake. Methods Acetylene progesterone was conjugated with pegylated phenylboronic acid via click reaction and radiolabeled with 131 I at the same time to afford 131I‐EIPBA. Meanwhile, 131 I‐EIPB without boronate was prepared as control agent. To verify the potential of 131I‐EIPBA for PR‐positive cancer diagnosis, in vitro cell uptake study, in vivo biodistribution, and micro‐SPECT imaging were performed. Results 131 I‐EIPBA was obtained with moderate radiochemical yield (40.35 ± 3.52%) and high radiochemical purity (>98% after HPLC purification). As expected, in cell uptake study, it had a binding affinity of 39.6 μM for PR. The internalization ratio of 131I‐EIPBA was remarkably higher than that of 131I‐EIPB in MCF‐7. In contrast, nucleus uptakes of 131I‐EIPB (0.13 ± 0.013%) were found to be significantly lower than that observed with 131 I‐EIPBA (0.59 ± 0.007%) in PR‐positive MCF‐7 cells. Furthermore, the biodistribution studies showed that 131 I‐EIPBA had higher uptake in MCF‐7 tumor than 131 I‐EIPB. Conclusions Using the aromatic boronate motif to improve nucleus uptake provides a worthwhile strategy for breast cancer diagnosis via enhanced nuclear receptor PR targeting. In vivo evaluation of this modified radioiodination probe by biodistribution and micro‐SPECT imaging are under progress. Scheme 1. The synthesis of 131I labeling of 131I‐EIPBA, and 131I‐EIPB. ACKNOWLEDGMENTS This study was financially supported by the National Key Basic Research Program of China (2014CB744503). R EF E RE N C E S 1. Ono M, Tsuda H, Yoshida M, Shimizu C, Kinoshita T, Tamura K, 2016, Original Study, Vol. 17, No. 1, 41‐47. 2. Tang R, Wang M, Ray M, Jiang Y, Jiang Z, Xu Q, and Rotello VM, 2017, JACS, 139 (25), pp 8547–8551.
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P os t er C at egor y: Rad i och em i s t ry ‐ Other Radionuclides P-157 | Production, formulation, and quality control of [13N]NH3 for clinical use Pardeep Kumar; Raman Joshi NIMHANS, India
Introduction [13N] ammonia (NH3) has been used as positron emitting agent, approved by the US‐FDA for PET imaging of the myocardium under rest or pharmacologic stress and many other studies proving its role in the differential diagnosis of gliomas and brain inflammatory lesions. In this study, we have produced, formulated [13N]NH3, and performed quality controls. Objective To standardize the production of [13N]NH3 at our newly set up cyclotron facility and make it available for clinical use. Method The nuclear reaction [16O(p,α)13N] was chosen to produce [13N]NO3−/NO2− by bombarding naturally pure water with 16.5 MeV protons with intensity of 30 mA. [13N]‐NH3 was produced by adding [13N]NO3−/NO2− in a vial containing sodium hydroxide/DeVarda alloy (3:1). [13N]NH3 was formulated in normal saline at appropriate pH and pass through 0.22‐m filter in a sterile vial (three vial scheme, Figure 1). Radio‐TLC was performed on TLC scanner using 75% methanol as a solvent and silica coated aluminum sheets as stationary phase. Radio‐HPLC was performed on Dionex, Thermo‐fisher HPLC equipped with UV/Vis and radio‐detector using 95% acetonitrile used as a solvent and Acclaim polar advantage (C16, 3 mm, 2.1 × 100 mm) as a stationary phase. The pH was checked with pH paper. The endotoxin test was done using Endosafe Nexgen PTS (Charles river, USA) to confirm the sterility of the preparation.
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Results The radiochemical purity of [13N]‐NH3 was 97.6 ± 1.8%. The TLC showed retention time for [13N]‐NH3 was 5.8 ± 0.6 min as compare to 2.4 ± 0.4 min for [13N] NO3−/NO2−. Radio‐HPLC showed retention peak for [13N]‐NH3 was at 2.4 ± 0.3 min as compare to 1.2 ± 0.4 min for [13N]NO3−/NO2− (Figure 2). The final pH of the preparation was 6.6 ± 0.6. The endotoxin test was passed and endotoxin levels were below 30 EU/mL. The preparation is ready to use in patients. Conclusion The method of production was reproducible with high radiochemical purity. The endotoxin test ensured safety of the preparation for the patient use.
Poster Cate gory: Radiochemistry ‐ O t h e r Ra d i on u cl i d e s P-158 | TLR5 as a target for Flavopiridol effect on breast cancer in mice model Dai Shi
Purpose Although treatment options for patients with breast cancer have improved over time, high metastatic breast cancer remains incurable. Recently enhanced Toll‐like receptor (TLR) 5 expression was reported to be associated with breast cancer, and Flavopiridol, a cyclin‐dependent kinase 9 (CDK9) inhibitor, may be an effective new
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strategies for treatment of breast cancer. However whether the Flavopiridol interacts through TLR5 pathway is not fully understood. Methods We prepared radioiodine‐125 labeled anti‐TLR5, and investigated possible modulatory effects of flavopiridol on TLR5 in breast cancer cells lines 4T1 and EMT6 in vitro and in tumor‐bearing mice. Results The results show that breast cancer cell lines 4T1 and EMT6 exhibited higher and lower expression of TLR5. Flavopiridol can drastically decrease survival in breast cancer cell lines at nanomolar concentrations positively co‐related with TLR5 expression in vitro. I‐125 labeled anti‐TLR5 could bind specifically to breast cancer cells in vitro with high affinity. Further, in vivo assessment of the therapeutic effects of flavopiridol on breast cancer‐bearing mice resulted in a significant reduction of tumor volume in mice at concentrations that are physiologically tolerable. I‐125 labeled anti‐TLR5 could localize within tumor with high specificity after injected through tail vein. Flavopiridol decreased tumor growth positively related with tumor TLR5 expression without obvious weakening under Flavopiridol application. Finally, we checked that the relation between TLR5 and CDK9 in breast cancer cells. The results show that inhibit CDK9 could apparently down‐regulate expression of TLR5 and NF‐kB P65. Conclusion This study suggests that anti‐tumor effect of Flavopiridol may carry out through inhibiting TLR5‐NF‐kB pathway, and local TLR5 could be a molecular target for monitoring tumor growth.
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Poster Cate gory: Radiochemistry ‐ O t h e r Ra d i on u cl i d e s P-159 | Direct nucleophilic radioiodination and astatination of antibodies via pre‐conjugated arylboronic acids Marion Berdal1; Laurent Navarro2; Cyrille Alliot4; Michel Chérel1; Alain Faivre Chauvet5; Jean‐François Gestin1; François Guérard3 1
CRCINA, Inserm, CNRS, France; 2 CRCINA, France; 3 Université de
Nantes, CRCINA, Nuclear Oncology group; 4 Arronax, France; 5 University of Nantes, France
Objectives While astatine‐211 and iodine radioisotopes are of high interest for radioimmunotherapy and nuclear imaging, available methods to bind them to carrier monoclonal antibodies (mAb) are still far from optimal. Direct radioiodination with electrophilic iodine (I+) leads to substitution with mAb tyrosines with limited in vivo
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stability whereas electrophilic astatination do not lead to an At‐tyrosine bond, but instead to a highly unstable and uncharacterized labeling. Consequently, to obtain sufficient stability, the formation of a stable bond with a prosthetic group (PG) conjugated to the mAb is thus mandatory. Ideally, the PG should be conjugated to the mAb before radiolabeling to avoid radioactive loss during the bioconjugation step that is observed when radiolabeling of PG is performed prior to conjugation.1 If solutions have been reported for direct astatination of mAb, they are based on an electrophilic destannylation reaction that requires the electrophilic At+ species which is unstable in solution and thus that do not guaranty consistent labeling efficiency.2 Furthermore, such approach is not applicable to radioiodination since electrophilic labeling of tyrosine occurs competitively with the expected iododemetalation of the preconjugated prosthetic group. Thus to date, no common method is known for direct labeling of mAb with radioiodine and astatine. In this context, our objective was to investigate if nucleophilic approaches could be a solution to issues encountered in radioiodination and
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astatination of mAb via electrophilic pathways, namely, the competitive reactivity of I+ with tyrosine, and the instability of At+. Methods The first step consisted in identifying the best class of precursors that could efficiently be radioiodinated and astatinated by nucleophilic approach in aqueous media (min 90% water) and at low temperature compatible with mAbs. For this, several compounds reported previously as efficient nucleophilic radiohalogenation reactions in organic medium were chosen from aryliodonium salts,3 aryliodonium ylides,4 arylsulfonium salts5 and arylboronic acids or esters.6 Then, we focused on the use of arylboronic acids with copper catalysis. On a model compound (4‐chlorobenzeneboronic acid), labeling conditions in water were optimized (influence of pH, buffer salt nature and precursor, catalyst and ligand concentration) to make the reaction efficient with the lowest possible precursor and catalyst concentration. Optimal conditions were then transferred to the labeling of 2 mAbs (an anti‐CD22 and our home made anti‐CD138 mAb) pre‐modified by conjugation to 3‐carboxyphenylboronic acid NHS ester. Labeling efficiency and radiolabeled mAb integrity were then assessed. Results Of the precursors tested, only arylboronic acids in the presence of Cu(OTf)2Pyr4 catalyst and 1,10‐ phenanthroline ligand provided high radioiodination and astatination RCYs in aqueous solution at room temperature. Optimization of conditions with 4‐ chlorobenzeneboronic acid showed that a pH ≤ 6.5 was required to provide RCYs (> 90%) with low precursor concentrations (≤ 250 μM). For use of this method with mAbs, the most compatible buffer in which the high RCYs were maintained and that prevented copper salt and/or mAb precipitation was found to be the TRIS buffer. Under these conditions, high radioiodination and astatination RCYs (> 80%) were also obtained with both mAbs tested with an excellent preservation of Immunoreactivity (94% for 125I‐anti‐CD138 and 86% for 211 At‐anti‐CD138) which validated our concept. Conclusions This study proves for the first time the possibility to label mAbs in a single step with radioiodine and astatine‐211 by a nucleophilic approach. Labeling efficiency and resulting immunoreactivity of labeled mAb were high which warrants further in vivo evaluation. Additionally, this is the first reported method that can be used for both radioiodination and astatination which should facilitate
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the development of theranostic tools based on these radionuclides. ACKNOWLEDGEMENT This research was supported in part by grants from the French National Agency for Research, called “Investissements d'Avenir” IRON Labex no. ANR‐11‐ LABX‐0018‐01 and ArronaxPlus Equipex no. ANR‐11‐ EQPX‐0004, and by grant INCa‐DGOS‐Inserm_12558. RE FER EN CES 1. Guérard, Bioorg. Med. Chem. 25, 5975‐5980 (2017) 2. Aneheim, Bioconjugate Chem. 27, 688–697 (2016) 3. Guérard, Chem. Eur. J. 22, 12332–12339 (2016) 4. Rotstein, Nat Commun 5, (2014) 5. Mu, Eur. J. Org. Chem. 2012, 889–892 (2012) 6. Reilly, Org. Lett. 20, 1752–1755 (2018)
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-161 | Synthesis and validation of [18F]6″‐ fluromaltotriose, a radiotracer for imaging bacterial infections Tom Haywood; Mohammad Namavari; David Anders; Sam Gambhir Stanford University, USA
Objectives The main aim of this work was to develop a radiochemical synthesis procedure for the clinical translation of [18F]6″‐Fluromaltotriose. Previous synthetic procedures involved manual manipulations and procedures not compatible with good manufacturing practices (GMP) conditions.1 Methods All synthetic steps were performed on a GE Tracerlab FX‐N Pro synthesis unit. 18F− was delivered to the synthesis unit from the cyclotron (GE PET Trace 880). Azeotropic drying with kryptofix and potassium carbonate was followed by labelling of the precursor (6″‐(4‐nitrophenylsulfonyl)‐maltotriosedecaacetate) in DMF at 85°C for 15 minutes. Following radiolabeling, the reaction mixture was diluted with water and trapped on a C18 Lite SPE cartridge. Then eluted with MeCN into the second reactor where the MeCN was removed
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in vacuo followed by hydrolysis of the acetate protecting groups in 2M HCl at 120°C for 15 minutes to yield the crude [18F]6″‐Fluromaltotriose product. The solution was neutralized by addition of NaOH solution. The reaction mixture was purified by HILIC mode semi‐prep HPLC. Reformulation then carried out by trapping the product on an amino propyl SPE cartridge followed by washing with ethanol and elution with Saline for an injectable dose. Analytical HPLC is performed using a radioactivity detector and a charged aerosol detector due to [18F]6″‐Fluromaltotriose not containing a chromophore. Results The new radiochemistry method for [18F]6″‐ Fluromaltotriose gave good radiochemical yield, radiochemical purity of >95%, and good molar activity. The new method is fully automated, meaning less radiation exposure to the radiochemist and a more reproducible production. Conclusions We have successfully translated the synthesis of [18F]6″‐ Fluromaltotriose from a semi‐automated method with manual operations to a fully automated method on a GE Tracerlab FX‐N Pro, giving good yields, higher purity and a method which is in compliance with GMP for translation into the clinic. This new automated and
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GMP method allows facile translation of the radiotracer to other radiochemistry facilities with access to 18F−. RE FER EN CES 1. Namavari, M. et al. A novel synthesis of 6′′‐[18 F]‐ fluoromaltotriose as a PET tracer for imaging bacterial infection. J. Label. Compd. Radiopharm. 61, 408–414 (2018).
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-162 | A concentration method for efficient microscale one‐pot radiosynthesis of [18F]FET and [18F]fallypride Ren Iwata1; Claudio Pascali2; Kazunori Terasaki3; Yoichi Ishikawa4; Ryuichi Harada5; Shozo Furumoto1; Kazuhiko Yanai5 1
Tohoku University, Japan; 2 Fondazione IRCCS Istituto Nazionale
Tumori, Italy; 3 Cyclotron Research Center, Iwate Medical University, Japan; 4 Cyclotron and Radioisotope Center, Tohoku University, Japan; 5
Graduate School of Medicine, Tohoku University, Japan
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Objectives Microscale one‐pot radiosynthesis of 18F‐labeled probes is a practical method for reducing the amount of precious precursor without any significant decrease in radiochemical yields (RCYs). In this study, we aimed to develop a method allowing to improve the RCYs of [18F]FET (O‐2‐[18F]fluoroethyl‐L‐tyrosine) and [18F] fallypride even on a very small 5‐10 μL scale. Methods A 5‐20 μL portion of 20 mM K.222/KHCO3‐MeOH was added to a disposable micro sample vial (300 μL, glass or polypropylene). To the vial was added a MeOH eluate containing K.222/K[18F]F (ca. 270 μL), prepared using Oasis MAX and MCX cartridges as previously described1,2 and shown in Figure 1. Three procedures for preparing a reaction solution were compared for RCY of [18F]FET and [18F]fallypride. Procedure A: DMSO (5‐20 μL) was added to the MeOH eluate and the mixture was gently evaporated (85°C, 200 mL/min He flow), leaving [18F]fluoride concentrated in the low volume of DMSO. After that 5‐20 μL of precursor solution in MeCN (TET 17.7 μmol/mL; tosyl‐fallypride 3.9 μmol/mL) were added. Procedure B: To the
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DMSO‐MeCN solution of the precursor prepared by the same way as Procedure A was added extra MeCN (40‐50 μL). Procedure C: The MeOH eluate was evaporated to dryness (85°C, 200 mL/min He flow) and to the residue were added DMSO (5‐20 μL), the precursor solution (5‐20 μL) and additional MeCN (20‐50 μL). In all 3 procedures, MeCN was then gradually evaporated at 120‐130°C for 5‐10 min through a vent in the vial septum, resulting in an increased concentration of precursor in DMSO. During this time the reaction took place. In the case of [18F]FET HCl (2 M, 20 μL) was then added, and the mixture was heated at the same temperature for another 5 min. Finally, both reactions were quenched by addition of aqueous KF and MeOH. The radioactive products were analyzed by HPLC for determining the RCYs. Effects of radiation and carrier amount on the microscale radiosynthesis of [18F]FET were also investigated. Results RCYs of [18F]FET obtained by Procedure A were satisfactorily high and consistent down to 10 μL (ca. 60%) but markedly decreased at 5 μL (ca. 40%). They were improved up to over 80% by Procedure B,
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while they turned out to be even better reproducible by Procedure C. Most relevant, no noticeable decrease in RCY was observed with the latter even at 5 μL probably due to no loss of DMSO during the MeOH evaporation step. The results suggested further decrease in reaction scale below 5 μL. The RCYs of [18F]fallypride (ca. 20%) at 10 μL obtained by Procedure A were also doubled (ca. 40%) by Procedures B and C, whereas the RCYs at 10 μL could be increased up to over 80% by increasing the volume of the precursor solution to 50 μL, simply because this allowed for a 5 times more concentrated precursor during the labeling reaction in DMSO. A further advantage resulting from microscale radiosynthesis was the rapid purification of crude [18F] FET achieved by means of a small analytical HPLC column. No notable effects by radiation and carrier amount was observed on 10 μL scale radiosynthesis of [18F]FET. Conclusions The high yield productions of [18F]FET and [18F]fallypride obtained by the present microscale radiosynthesis proved the potential of the method using the concentration procedure, which could easily be applied to other 18 F‐labeled probes. In addition, the very low amount of reagents used is expected to greatly simplify the purification step. ACKNOWLEDGEMENT This work was supported by JSPS KAKENHI Grant Number 16H05383. R EF E RE N C E S 1. Iwata, R. et al. Appl. Radiat. Isot. 125, 113–118 (2017). 2. Iwata, R. et al. J. Label. Compd. Radiopharm. 61, 540–549 (2018).
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-163 | Facile two‐step one‐pot automated radiosynthesis of [18F]FET suitable for clinical PET study of brain tumors Min Wang; Barbara Glick‐Wilson; Qi‐Huang Zheng Indiana University School of Medicine, USA
Objectives O‐(2‐[18F]Fluoroethyl)‐L‐tyrosine ([18F]FET) is a derivative of amino acid L‐tyrosine. Due to its high stability
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in vitro and in vivo, high uptake in the primary brain tumors and fast tumor kinetics, low susceptibility to accumulation in healthy tissues, higher specificity for imaging amino acid metabolism in tumors, and long half‐life, [18F]FET has become a promising amino acid PET (positron emission tomography) tracer for diagnosis and detection of brain tumors. However, there are some limitations in radiosynthesis such as limited commercial availability and complicated synthetic procedures, which make it less frequently used in many PET centers.1–3 In addition, there are gaps in radiosynthetic detail among the published methods, and certain key steps gave poor or widely variable radiochemical yields in our hands. Here we report a facile two‐step one‐pot automated radiosynthesis of [18F]FET using an home‐built automated multi‐purpose [18F]‐radiosynthesis module. Methods The precursor O‐(2‐tosyloxyethyl)‐N‐trityl‐L‐tyrosine tert‐butylester (TET) in DMSO was labeled with K[18F] F/Kryptofix 2.2.2 at 130°C for 20 min through nucleophilic substitution to form a [18F]‐labeled intermediate. The intermediate was then deprotected by 2.0 N HCl at 100°C for 5 min to give [18F]FET. The reaction mixture was neutralized with 1.0 N NaHCO3 and isolated by a semi‐preparative HPLC using Gemini C18 column (10 × 250 mm) with 10% EtOH/90% 100 mM NaH2PO4 buffer as mobile phase. The product fraction was collected in a recovery vial, formulated with 10 mL saline, then sterile‐filtered into a sterile vial. For analytical HPLC, a Luna C18(2) column was employed to monitor this two‐step radiosynthesis. The radiochemical purity, molar activity and enantiomeric purity were determined by analytical HPLC using Gemini C18 and Chirex®3126 (D)‐penicillamine columns. After optimized synthesis conditions and sequences, three consecutive [18F]FET production validation runs were performed. Results The precursor amount was decreased from 6‐10 mg to 2 mg; thus, a semi‐preparative HPLC column instead of a preparative column was used for purification. The use of the less precursor would also increase the chemical purity due to less precursor contamination. DMSO replaced CH3CN was used as reaction solvent, thus no evaporation of CH3CN and no filtration of precipitated solid steps after hydrolysis were needed; in addition, the labeling reaction can be conducted at higher temperature to increase the radiochemical yield. The amount of K2CO3 with Kryptofix 2.2.2 was doubled to increase the radiochemical yield as well. After acidic
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deprotection reaction, the reaction mixture was directly neutralized with 1.0 N NaHCO3 instead of 1.0 N NaOH, which would significantly prevent the elimination and hydrolysis reactions of [18F]FET. Analytical HPLC monitoring indicated the conversion yield of the labeling reaction was >95%, and no radiolabeled intermediate was detected during acidic deprotection reaction. However, [18F]FET might convert to vinyl by‐product via elimination, O‐(2‐hydroxyethyl)‐L‐tyrosine (HOET) via hydrolysis, and [18F]fluoride during the subsequent basic neutralization and semi‐preparative HPLC purification. The decay‐corrected radiochemical yield at end of bombardment (EOB) was 20‐25%. The radiochemical purity was >99%, and the molar activity was 185‐444 GBq/μmol at EOB. The overall synthesis time was 75‐80 min from EOB. The products from three repeat validation runs all met the established quality control (QC) criteria. Conclusions A facile two‐step one‐pot automated radiosynthesis of [18F]FET has been developed. [18F]FET produced in our self‐designed [18F]‐radiosynthesis module is suitable for clinical PET study of brain tumors. ACKNOWLEDGEMENTS This work was supported by Indiana University School of Medicine, Department of Radiology and Imaging Sciences in the United States. R EF E RE N C E S 1. Bourdier T, et al. Nucl. Med. Biol. 2011, 38, 645‐651. 2. Lakshminarayanan N, et al. J. Radioanal. Nucl.Chem. 2006, 310, 991‐999. 3. Siddiq IS, et al. Appl. Radiat. Isot. 2018, 133, 38‐44.
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Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-164 | Radio‐analytical RP‐HPLC methods for synthesis monitoring and quality control of [18F]FET Barbara Glick‐Wilson; Qi‐Huang Zheng; Min Wang Indiana University School of Medicine, USA
Objectives O‐(2‐[18F]Fluoroethyl)‐L‐tyrosine ([18F]FET) is known to have superior brain tumor imaging for positron emission tomography (PET) in the differential diagnosis of malignant and benign brain tumors.1 To address local investigator needs for [18F]FET‐PET, we develop a facile two‐step one‐pot automated radiosynthesis of [18F]FET using a self‐designed automated multi‐purpose [18F]‐radiosynthesis module. [18F]FET is synthesized by nucleophilic substitution of the precursor O‐(2‐ tosyloxyethyl)‐N‐trityl‐L‐tyrosine tert‐butylester (TET) with K[18F]F/Kryptofix 2.2.2 to form a [18F]‐labeled intermediate O‐(2‐[18F]fluoroethyl)‐N‐trityl‐L‐tyrosine tert‐butylester ([18F]FTET), followed by acidic deprotecting reaction to cleave the trityl and tert‐butyl protecting groups. This two‐step radiosynthesis of [18F]FET might contain two radioactive impurities, [18F]FTET and [18F]fluoride.2–4 By monitoring these two compounds, the radiosynthesis conditions can be optimized to achieve high radiochemical yield. In addition, several quality control (QC) procedures need to be performed prior to human administration.
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Radiochemical identity and purity, enantiomeric purity and molar activity are crucial QC measurements. Therefore, our aim was to develop radio‐analytical reverse‐phase (RP) high performance liquid chromatography (HPLC) methods to optimize the reaction parameters in two‐step radiosynthesis through a rapid and real‐time monitoring of [18F]fluoride conversion and [18F]FTET deprotection as well as to evaluate the radiochemical identity and purity, molar activity and enantiomeric purity for QC of [18F]FET. Methods Radio‐analytical RP‐HPLC monitoring and analysis were performed on a Waters 1525 Binary HPLC Pump system fitted with Waters 2998 Photodiode Array detector and Eckert and Ziegler γ‐detector. Method A for [18F]FET synthesis monitoring was conducted with a Phenomenex Luna C18(2) column, 4.6 × 250 mm, mobile phase 87% CH3CN/13% 4.0 mM CH3CO2Na, flow rate 1.8 mL/min, and UV 254 nm. During the development runs of [18F]FET synthesis, aliquots of sample in each step were drawn for HPLC analysis to monitor [18F]fluoride and [18F]FTET. Method B for [18F]FET QC to determine the radiochemical identity and purity, and molar activity was performed with a Phenomenex Gemini C18 column, 4.6 × 250 mm, mobile phase 12% EtOH/88% 50 mM NaH2PO4 buffer (pH 6.8), flow rate 1.0 mL/min, and UV 220 nm. Method C for [18F]FET QC to determine the enantiomeric purity was performed with a Phenomenex Chirex® 3126 (D)‐penicillamine column, 4.6×150 mm, mobile phase 12% i‐propanol/88% 2.0 mM CuSO4, flow rate 1.0 mL/min, UV 220 nm. Methods B and C were used in the development, validation and production runs for [18F]FET QC analysis. Results Within a 10‐min run, the retention time of FTET was 7.8 min in Method A, and the retention time of FET
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was 6.6 min in Method B. The optimal reaction parameters and synthesis sequences were established, based on the real‐time monitoring of two reaction steps with Method A. The results indicated the conversion yield of the radio‐nucleophilic substitution was >95%, and no [18F]FTET was detected during acidic deprotection. After purification and formulation, [18F] FET was obtained with 20‐25% radiochemical yield, decay‐corrected to end of bombardment (EOB). Method B showed the radiochemical purity of [18F]FET was >99%, and the molar activity was 185‐444 GBq/μmol at EOB determined by spiking method. Method C indicated the enantiomeric purity of [18F]FET was >99%. The [18F] FET products from three repeat validation runs all met the established QC criteria for clinical use. Conclusions These new radio‐analytical RP‐HPLC methods provide rapid and real‐time monitoring of [18F]fluoride conversion and [18F]FTET deprotection for optimization of the reaction parameters and synthesis sequences, and quality control for [18F]FET production on our home‐built automated multi‐purpose [18F]‐radiosynthesis module. [18F]FET produced in our PET chemistry facility is suitable for clinical use of PET brain tumors imaging. ACKNOWLEDGEMENTS This work was supported by Indiana University School of Medicine, Department of Radiology and Imaging Sciences in the United States.
RE FER EN CES 1. Malkowski B, et al. PLoS ONE, 2015, 10, 1‐10. 2. Bourdier T, et al. Nucl. Med. Biol. 2011, 38, 645‐651. 3. Lakshminarayanan N, et al. J. Radioanal. Nucl.Chem. 2006, 310, 991‐999. 4. Siddiq IS, et al. Appl. Radiat. Isot. 2018, 133, 38‐44.
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Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-165 | Automated synthesis of 5‐[18F] fluoro‐α‐methyl tryptophan (5‐[18F]F‐AMT) Joseph Blecha1; Thomas Hayes1; Luis Borrero Garcia2; William Chou2; Tony Huynh3; Denis Beckford‐Vera1; Mary Helen Barcellos‐Hoff2; Benjamin Franc1; Henry VanBrocklin1 1
University of California, San Francisco, USA; 2 UCSF Helen Diller
Comprehensive Cancer Center, USA; 3 UCSF Radiology and Biomedical Imaging, USA
Objectives Tryptophan is an essential amino acid that is metabolized in cancer by indoleamine 2,3‐dioxygenase 1 (IDO1) to L‐kynureine, promoting tumor growth and immune system suppression.1 Carbon‐11‐a‐methyl tryptophan was identified as an inhibitor of IDO1 and not a substrate for protein synthesis.2 Recently, a fluorine‐18 version, 5‐[18F]F‐AMT (Figure), has been shown to be taken up in melanoma xenografts.3 The inspiration behind the current project was to image brain metastatic cancer using 5‐[18F]F‐AMT. Based on the foundational synthetic effort work,3 we sought to automate the production of 5‐[18F]F‐AMT on the Sofie Biosciences ELIXYS FLEX/ CHEM module to prepare the tracer preclinical imaging studies and future human translational research studies. Methods The BPin precursor was prepared in 5 steps from methyl tryptophan as described in Giglio et al.3 The original labeling procedure utilized tetrabutyl ammonium [18F]fluoride, however in our hands the labeling was inconsistent. We employed a labeling technique published by Mossine et. al.4,5 to achieve consistent labeling. Labeling using the KOTf/K2CO3 system allowed us to concentrate the [18F]fluoride ion on a QMA sep pak without adding large amounts of K2CO3 into the BPin/copper catalyst reaction. Larger amounts of DMF (350 μL: 50 μL) was needed for the
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[18F]fluorination step, thus a C18 sep pak was required to lower the total reaction volume for the TFA decyclization step. DMF (50 μL) was back into the 500 μL of TFA to keep the hydrophobic compound soluble for the reaction. The TFA was evaporated and NaOH was added to the reaction for deprotection. The reaction mixture was neutralized and injected for purification onto an analytical HPLC. The product was collected, diluted, and loaded onto a C18 light sep pak. The final purified product was eluted with ethanol and taken to dryness. The final formulation of 0.9% saline was added and imaging studies were conducted. Results Incorporation yields (analyzed by radioTLC, non‐decay corrected) were sufficient and consistent (25% ± 5%, n = 5). The automation on the ELIXYS required volume and reaction condition adjustments to achieve suitable synthetic yields. The decyclization and deprotection scheme was one of the most challenging parts of the automation with various partially protected species being present in the HPLC purification. All of the possible species formed from various partial reactions are all separable on the HPLC using the gradient solvent system of 5: 95% acetonitrile with 0.1% TFA over 30 min. The addition of the 50 μL of DMF to the TFA led to more efficient decyclization. NaOH was substituted for KOH in the deprotection reaction as older KOH did not accomplish complete deprotection. Conclusions Automation of 5‐[18F]F‐AMT was completed on the Sofie Biosciences ELIXYS FLEX/CHEM module and the synthesis takes 120 ± 10 minutes, with a yield of 1.52 ± 1.04% (n = 3, decay corrected). Adequate amounts of 5‐[18F]F‐AMT (37‐185 MBq) were formulated and injected into the metastatic tumor model in mice to perform imaging studies. The purification of 5‐[18F]F‐AMT is still under examination, when larger volumes of the reaction mixture are loaded onto the HPLC the yield is lower. These lower amounts of purified product injections led directly to the low yields presented.
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ACKNOWLEDGEMENTS The work was supported by grant number W81XWH‐17‐ 1‐0033 from the US Department of Defense Breast Cancer Research Program (BF). R EF E RE N C E S 1. Routy JP et al., Int. J. Tryptophan Res. 9: 67‐77, 2016. 2. Chaly T, Diksic M. J. Nucl. Med. 29: 370‐4, 1988. 3. Giglio, BC et. al. Theronostics 7: 1524‐1530, 2017. 4. Mossine, AV et al., Org. Lett., 17: 5780‐5783, 2015. 5. Mossine, AV et al., J Lab. Compd. Radiopharm., 61: 228‐236, 2018
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-166 | Automated radiosynthesis of (2S,4R)‐4‐ [18F]fluoroglutamine for clinical application Yan Zhang1; Lifang Zhang1; Zehui Wu2; Jianhua Yang3; Karl Ploessl4; Zhihao Zha4; Liu Fei3; Hua Zhu; Lin Zhu5; Zhi Yang6; Hank Kung4 1
College of Chemistry, Beijing Normal University, China; 2 Beijing Institute
of Brain Disorders, Capital Medical University, China; 3 Department of Nuclear Medicine, Peking University Cancer Hospital, China; 4 University of Pennsylvania, USA; 5 Beijing Normal University, China; 6 Peking University, China
Objectives Recent reports suggested that (2S,4R)‐4‐[18F] 18 fluoroglutamine ([ F]FGln) may be useful for detecting and monitoring tumor metabolism based on glutamine utilization.1–3 After an iv injection [18F]FGln demonstrated good uptake and a high tumor‐background ratio in patients; PET imaging with [18F]FGln may be an attractive alternative tracer, other than commonly used [18F]FDG, for clinical diagnosis and therapy evaluation (Figure 1). We report the experience, successes as well as failures, in the past one year, using PET‐MF‐ 2V‐IT‐I modular synthesizer for preparing [18F]FGln in the PET/Cyclotron facility of Peking University Cancer Hospital for clinical application. Methods [18F]FGln was prepared using a two‐step radiochemical reaction described in Figure 1. Briefly, nucleophilic fluorination of the tosylate precursor in acetonitrile with anhydrous K[18F]F−/18‐Crown‐6 at 90°C for 15 min. The reaction mixture was diluted with 10 mL water,
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and passed through an Oasis HLB light cartridge (Waters). The cartridge was washed twice with water (2 × 10 mL) and 10 mL 20% ethanol/water (v/v). The intermediate trapped in the cartridge was eluted with 1.5 mL acetonitrile into reactor vial R2. This eluted intermediate was heated at 60°C under a stream of N2 to remove acetonitrile. To this dried residue in vial R2 TFA/anisole mixture (1 mL/10 μL) was added. The resulting solution was heated at 60°C for 5 min to remove the protecting groups. The volatiles were removed at room temperature under a stream of N2. Sterile water was added into vial R2. The content was transferred through a column (C18‐AG 11 A8) and a sterile filter to the final product vial. R2 was rinsed with 3 mL sterile water. The final product was diluted with appropriate volume of sterile saline. Quality control tests (requirements of Chinese Pharmacopeia), including appearance, pH, radiochemical identity and radiochemical purity, radionuclide identity, residual solvent (acetonitrile), sterility and bacterial endotoxin, were carried out. The final product, [18F]FGln, which meets release criteria is transferred to nuclear medicine clinic for patient injection. Results The two‐step automated radiosynthesis of [18F]FGln was performed on a PET‐MF‐2V‐IT‐I synthesizer. The process was validated for each batch of new precursors. The total radiosynthesis time was about 65 min, the decay‐corrected radiochemical yield was 18 ± 4% (n = 54) and the radiochemical purity was greater than 90%. When comparing with previously reported HPLC purification method,4 there was a significant increase in efficiency associated with using the SPE method by reducing preparation time in synthesis and reducing product loss. There were successful preparations (n = 54), while there were also many failures (n = 12). Because of water contamination in TFA and instability of the precursor, there were often unsuccessful radiosyntheses, and the radiochemical purity was lower than 90%. An unsuccessful synthesis also led to samples containing hydrolyzed side product, (2S,4R)‐4‐ [18F]fluoroglutamic acid. The failures led to abandoning the clinical scan which causes not only inconvenience to patients but also disappointment to clinicians. Careful planning and prior validations will be essential to ensure the success of preparation of [18F]FGln for clinical application. Conclusions We report successes and failures of synthesizing (2S,4R)‐ 4‐[18F]fluoroglutamine, [18F]FGln, on a fully‐automated PET‐MF‐2V‐IT‐I synthesizer under GMP‐compliant
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The First Affiliated Hospital of Jinan University, China; 2 Department of
PET‐CT Diagnostic, Tianjin Medical University General Hospital, Tianjin, China; 3 Guangzhou Hightech Radiopharmaceutical Co. Ltd, Guangzhou, China; 4 MGH/Harvard, USA
Objectives Translocator protein (TSPO) serves as a critical biomarker in the process of neuroinflammation.1 [18F] FDPA, developed by Solin2 and our group,3 has proven to be an excellent radiotracer for PET imaging of neuroinflammation in the ischemic and Alzheimer's disease mouse models. The objective of this study was to translate the SCIDY‐based [18F]FDPA labeling strategy to the clinical automation radiosynthesis for human use.
conditions. The experience helps to identify critical steps and pitfalls for preparation of this otherwise clinically useful metabolic probe for imaging tumor metabolism. ACKNOWLEDGMENTS This work was financially supported in part by the Beijing Natural Science Foundation (7171002) and the Beijing Science and Technology Project (Z151100003915116). R EF E RE N C E S 1. Venneti S, Dunphy MP, Zhang H, et al. Glutamine‐based PET imaging facilitates enhanced metabolic evaluation of gliomas in vivo. Sci Transl Med. 2015;7(274):274ra217. 2. Liu F, Xu X, Zhu H, et al. PET imaging of 18F‐(2S,4R)4‐ fluoroglutamine accumulation in breast cancer: From xenografts to patients. Mol Pharm. 2018;15(8):3448‐3455. 3. Xu X, Zhu H, Liu F, et al. Imaging brain metastasis patients with 18 F‐(2S,4R)‐4‐fluoroglutamine. Clin Nucl Med. 2018;43(11): e392‐e399. 4. Qu W, Zha Z, Plössl K, et al. Synthesis of optically pure 4‐fluoro‐ glutamines as potential metabolic imaging agents for tumors. J Am Chem Soc, 133:1122‐33, 2011.
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-167 | Spirocyclic iodonium ylide (SCIDY)‐ mediated automatic radiolabeling of [18F]FDPA and validation for human use Lu Wang1; Shaobo Yao2; Honghao Zhu1; Ruikun Tang3; Hao Xu1; Steven Liang4
Methods The SCIDY precursor was prepared as our previous report.3 [18F]FDPA labeling was conducted by an automated GE TRACERlabTM FXFN radiosynthesis module. The nucleophilic radiofluorination occurred with tetrabutyl ammonium [18F]fluoride (TBA[18F]/TBAOMs) in acetonitrile at 120°C for 12 min. The product was purified via radio‐HPLC, concentrated by C18 SPE cartridge, and formulated with 1 mL of EtOH and 9 mL of 0.9% NaCl solution for injection. Three consecutive productions of [18F]FDPA were carried out to validate for human use. Results The SCIDY precursor was synthesized in an overall yield of 30% with high purity (>99%) as a white solid. The formulated [18F]FDPA was obtained in non‐decay corrected (n.d.c) radiochemical yields of 12 ± 2%, with specific activities of 196 ± 55 GBq/μmol (5.3 ± 1.5 Ci/μmol) at the end of synthesis (60 min, n = 3). Clear colorless liquid was collected in a sterile vial and no suspended particles were observed. Both HPLC and radio‐TLC confirmed high chemical and radiochemical purities (>98%). The integrity of the final filter was demonstrated by a bubble point filter test (>50 psi). Formulated [18F]FDPA maintained stability, as measured by HPLC and radioTLC, as well as clarity and a pH of 6‐7 over a period of 6 h. The half‐life was verified to be 110 min by a dose calibrator. The formulated product was free of pyrogens (bacterial endotoxin < 5 EU/mL) and sterile. The tetrabutyl ammonium species was analyzed by visual spot test,4 and organic solvent analysis was carried out by GC‐FID, which showing residual TBA cation (99%. The formulated product was pyrogen‐free and sterile. Residual solvents met ICH requirements. QC analysis is under 25 minutes meaning final release (excluding sterility) takes less than one half‐life's of radioisotope. Conclusion A fully automated radio‐synthesis of [18F]NAV4694 has been successfully implemented and validated and provides clinical grade doses of product in agreement with PIC/S GMP. R EF E RE N C E 1. Swahn B‐M, Sandell J, Pyring D, Bergh M, Jeppsson F, Juréus A, Neelissen J, Johnström P, Schou M, Svensson S, Bioorganic & Medicinal Chemistry Letters, 2012, 4332–4337
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Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-178 | Automated handling of carbon‐11 waste gases Matthew Shadwell; Michael Izard; Nikolas Paneras; Emmy Hoffman; Gary Perkins ANSTO, Australia
Objective The radiopharmaceutical production process produces many forms of waste. The most common forms are liquid and solid waste but in the case of carbon‐11, gaseous waste must also be considered. This begins at the cyclotron with the most widely used carbon‐11 starting materials been either methane or carbon dioxide. In the case of carbon dioxide, it may be used directly or converted to other useful forms such as methyl iodide. These steps are often undertaken in the gas phase which gives further opportunity for release into both the work and surrounding environment. Various methods have been employed to control these unwanted radioactive waste gases but most facilities still use a passive gas capture bag. At the ANSTO Camperdown National Imaging Facility, we proposed a cost effective automated active system to draw the unwanted radioactive waste gases to a remote location where they could be stored for decay before been released into the building ventilation. Methods [11C]Carbon dioxide was used as the starting material in the production of Raclopride on a Synthra MeI and GPextent modules. Hotcells housing these modules are connected to the facility ventilation where the air passes through an in‐cell carbon filter before a building carbon filter and final HEPA filtration. The stack is constantly sampled for radioactive gases via a vacuum pump. The sampled gas flows at ~5 L/min through a 98.5‐mL cylindrical aluminium sampling chamber and is piped back into the stack downstream of the intake point. This flow‐through sampling chamber is continuously monitored by a gamma (NaI) detector (at contact) housed within lead/copper shielding. Results The final Gas Extraction System (GES) consists of two main assemblies, one within the synthesis hotcell and one in a remote location. By monitoring the pressure
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within the module's exhaust, it was possible to actively draw the unwanted radioactive waste gases away from the work environment and into the 330 L remote vessel for decay before release. This is done via a microcontroller which ensures the hysteresis of the pressure is maintained preventing over pressurisation or depressurisation. To ensure that waste gases do not linger within the working environment, the transfer line was reduced from 8 mm to 4 mm which saw an approximately 4 min drop in transfer time. Also observed was a nearly 90% drop in the stack emissions of the facility. Conclusions The Gas Extraction System designed and installed at the Nation Research Cyclotron Facility has resulted in significant safety improvements and radioactive waste gas handling effectiveness for carbon‐11 production. The system is large enough to handle multiple (>3/day) runs at full production. It also reduces the potential for personal dose and exposure and as a consequence the facility is now able to conduct three full production runs within the same cell in a day. The cost of the complete project was less than $AUD 10,000 representing a cost effective solution to handling radioactive waste gases that could be adopted by other facilities. ACKNOWLEDGEMENTS The authors acknowledge the facilities and scientific and technical assistance of the National Imaging Facility, a National Collaborative Research Infrastructure Strategy (NCRIS) capability, at the ANSTO/University of Sydney node.
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-179 | Automated cartridge remover for radioactive solid waste handling in radiopharmaceutical production Michael Izard; Lucy Griffith; Jack Markham; Nikolas Paneras; Gary Perkins ANSTO, Australia
Objectives Radioactive waste that is produced as part of the radiopharmaceutical production process must be removed to allow safe re‐entry of hotcells if more than one production is to be performed per day. In the cases of liquid and gaseous waste, this can be done be moving the waste to a remote location but for solid waste this possess a much greater technical difficulty. At the ANSTO Camperdown National Imaging Facility, we propose a cost effective Automated
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Figure 1 Synthra RNplus layout showing five possible locations of solid radioactive waste Cartridge Remover (ACR) to remove the unwanted solid radioactive waste allowing multiple productions to be performed on the same module within the same day. To allow for these multiple synthesis, we needed to ensure the dose rate within the hotcell was reduced below 100 uSv/hr. Methods Production of [18F]‐PBR111 was performed on a Synthra RNplus synthesis module (Figure 1). This module has the possibility to perform five different Solid Phase Extractions (SPE). By removing these five points on to a removable cassette allows for the possibility to perform a clean of the synthesis module remotely via the ANSTO Camperdown Multi Squirt.1 Results At the end of synthesis, the dose rate within the hotcell is approximately 2.5 mSv/hr (starting from 65 GBq). Through the introduction of the ACR, these end of synthesis dose rates are dramatically reduced to 750 μSv/hr once the solid waste is removed. After cleaning and removal of the liquid waste, the dose rate is observed to be approximately 140 μSv/hr. Given the half‐life of fluorine‐18 (110 min), this allows operators to re‐entre the hotcell safely after approximately 1 hour of decay. Conclusions Through the removal of solid radioactive waste, it is possible to safely preform multiple fluorine‐18 productions within the same day on the same module. The ACR maintains the flexibility of the module without having to predetermine the synthesis that will be performed through preloaded cassettes. ACKNOWLEDGEMENTS The authors acknowledge the facilities and scientific and technical assistance of the National Imaging Facility, a National Collaborative Research Infrastructure Strategy (NCRIS) capability, at the ANSTO/University of Sydney node. RE FER EN CE 1. Perkins G. J. et al, ANZSNM Poster 2015.
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Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-180 | First in Southeast Asia (Singapore) clinical study utilizing an automated synthesis of [11C]metomidate on Tracerlab Fx C Pro in compliance with PIC/S GMP Xin Jie Wee1; Mohd Fadli Bin Mohammad Noh1; Shi Yuan Jeow1; Ravi Vedarethinam2; Fathollah Zakee Bin Fatholmoein4; Chun Shing Lee1; Geraldine Pek2; Hazel Tay Siang Ping1; David Green2; Evelyn Laurens; Vi King Chiam1; Katja Boodeea4; Priyal R. Doshi; Akbar Kulasi1; Elaine Tan Jia Hui2; Troy H. Puar1; Ashley Weekes1; Edward Robins3 1
Clinical Imaging Research Center, Singapore; 2 A*STAR‐NUS Clinical
Imaging Research Centre (CIRC), Singapore; 3 Singapore Bioimaging Consortium, Singapore; 4 National University of Singapore
Objective [11C]Metomidate ([11C]MTO) has been previously described to be accurate and reliable positron emission tomography (PET) tracer for 11B‐hydroxylase activity, exhibiting high specificity and affinity for CYP11B enzymes in the adrenal cortex. Herein we report the fully automated synthesis of [11C]MTO under PIC/S GMP conditions at CIRC in Singapore for use in the first clinical study in Southeast Asia. Method The GMP complaint manufacture of [11C]MTO was performed utilizing a GE Tracerlab FX C Pro and Eckert & Ziegler dispensing system. [11C] Carbon dioxide ([11C] CO2) is produced with a GE PETtrace 860 via the 14 N(p,α)11C nuclear reaction using high purity nitrogen gas containing 1% oxygen as target material. The resulting [11C]CO2 is converted to [11C]methyl iodide and reacted with (R)‐desethyl‐etomidate precursor (3.0 mg) in dimethylformamide (0.6 mL) in the presence of Tetrabutylamommium hydroxide (6.0 μl). The reaction mixture was heated to 130°C for 2 minutes followed by purification on a semi‐preparative reverse phase HPLC. The desired fraction was collected and purified on a SPE cartridge (SepPak®Light C18). Finally, the product was eluted and reformulated in ethanol (1.2 mL) and saline (11 mL) where the product was then filtered with a 0.22‐μm sterile filter prior to dispensing into 4 separate vials (patient, sterility, QC and retention). Result Three consecutive batches of [11C]MTO were carried out to validate the radiopharmaceutical for human use in
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accordance with PIC/S GMP. High radiochemical and chemical purity of >99% was determined by fast HPLC analysis at QC. The formulated product was pyrogen‐free and sterile. Residual solvents met ICH requirements. Total synthesis time for [11C]MTO was 25‐30 minutes and QC analysis was under 25 minutes meaning final release (excluding sterility) takes less than two half‐lives of radioisotope. Conclusion A fully automated radio‐synthesis of [11C]MTO has been successfully implemented and validated providing clinical grade doses of product in agreement with PIC/S GMP. Human PET imaging of this radiopharmaceutical has already commenced at CIRC imaging. This project is a collaborative study between multiple hospitals in Singapore. Pilot study has been initiated and to date, more than 10 subjects have undergone PET/CT imaging at CIRC in 2018 and the findings will be reported in due course. ACKNOWLEDGMENT This work has been funded by a NMRC CS‐IRG NIG Grant. RE FER EN CE 1. Timothy, J. B et al. (2012) J. Clin. Endocrino.l Metab., 97, 100–109.
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-181 | Fast HPLC quality control (QC) analysis of [18F]MK6240 using a core‐shell particle column in partnership with Cerveau Technologies Fathollah Zakee Bin Fatholmoein1; Chun Shing Lee1; Geraldine Pek1; Hazel Tay Siang Ping1; Mohd Fadli Bin Mohammad Noh2; Shi Yuan Jeow2; Ravi Vedarethinam1; Xin Jie Wee3; David Green1; Evelyn Laurens1; Vi King Chiam4; Katja Boodeea1; Priyal R. Doshi1; Akbar Kulasi2; Elaine Tan Jia Hui1; Ashley Weekes5; Edward Robins6 1
A*STAR‐NUS Clinical Imaging Research Centre (CIRC), Singapore;
2
Clinical Imaging Research Centre, Singapore; 3 Clinical Imaging
Research Center, Singapore; 4 Clinical Imaging Research Centre Singapore, Singapore; 5 Clinical Imaging Research Centre (CIRC), Singapore; 6 Singapore Bioimaging Consortium, Singapore
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Objective [18F]MK6240 is a current leading PET tracer for tau imaging with pathological evidence that relates mutually with cognitive decline in Alzheimer's disease (AD). As part of CIRC's collaboration with Cerveau Technologies, we aim to have this tracer available for use in study in Singapore. As such we hope to develop a rapid QC HPLC analysis for the release of [18F]MK6240 in compliance with PIC/s GMP to enable multiple patient scanning per production. Method [18F]MK6240 was produced, purified and reformulated using Tracerlab FX N Pro in a modified literature procedure.1 In order to have a rapid analysis for the chemical purity of the [18F]MK6240 reference standard and the precursor, a core‐shell particle column (Poroshell 120 EC‐C18 3 × 50 mm 2.7 micron) was utilized and analysed in gradient mode with acetonitrile and water spiked with 0.1% TFA as mobile phases. Result Rapid QC analysis was achieved greatly due to fast HPLC analysis using a short core‐shell particle column rather than classic columns.1 The method has a limit of detection (LOD) of 0.03 μg/mL for MK6240 which is much lower than the required specification of 1 μg/mL thus showing the method is not only faster than currently literature method but also extremely sensitive. Conclusion Among the benefits of using a core‐shell particle column is that it allows for a much shorter analysis time by increasing the flow rate while maintaining a lower pressure.2,3 This fast HPLC method is validated and
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qualified for QC analysis of the [18F]MK6240 batches following PIC/S GMP for clinical trials at CIRC. Acknowledgement Cerveau Technologies for supporting the provision of precursor and reference material to CIRC. This study was part of MSc project at National University of Singapore (NUS) by Fathollah Zakee Bin Fatholmoein. RE FER EN CES 1. Collier TL, Yokell DL, Livni E, Rice PA, Celen S, Serdons K, Neelamegam R, Bormans G, Harris D, Walji A, Hostetler ED, Bennacef I, Vasdev N, cGMP production of the radiopharmaceutical, 2017, 60, 5 263‐289. 2. González‐Ruiz V, Olives AI, Martín MA, Core‐shell particles lead the way to renewing high‐performance liquid chromatography, TrAC, Trends Anal. Chem., 2015, 64 17‐28. 3. Fekete S, Olah E, Fekete J, Fast liquid chromatography: the domination of core‐shell and very fine particles, J. Chromatogr. A, 2012, 1228 57‐71.
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-182 | Using a microdroplet reactor for rapid, nucleophilic synthesis of [18F]FDOPA Jia Wang1; Travis Holloway1; R. Michael van Dam2 1
UCLA, USA; 2 UCLA Crump Institute for Molecular Imaging, USA
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Objectives Increasing interest in the PET tracer 3,4‐dihydroxy‐ 6‐[18F]fluoro‐L‐phenylalanine ([18F]FDOPA) to image neuroendocrine tumors, brain tumors, and Parkinson's disease, has led to the demand for a simplified synthetic procedure for its production. Several nucleophilic synthesis methods have been reported that avoid the issues of electrophilic synthesis, i.e., low availability of [18F]F2 and low molar activity. Building on recent advances in microdroplet radiochemistry, we adapted a previously reported method using diaryliodonium salt precursor1 to our microfluidic synthesizer,2 resulting in a rapid, straightforward synthetic process after optimization. Methods Synthesis was implemented on a silicon microfluidic chip (25 × 27.5 mm2), consisting of a hydrophilic reaction zone (4mm diameter) surrounded by a hydrophobic Teflon‐coated surface, that was affixed to a temperature control platform. First, a 10‐μL droplet of [18F]fluoride solution containing Kryptofix 222 (8.4mM) and K2CO3 (4.1mM) in 90:10 H2O:MeCN(v/v) was loaded on the chip and dried at 100°C for 1 min. Then, a 10‐μL droplet of ALPDOPA precursor in diglyme containing the radical scavenger 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) was added.3 During the fluorination reaction, additional diglyme was added to replace solvent that had evaporated. Finally, a 10‐μL droplet of H2SO4 (6M) was added, and the reaction mixture covered with a Teflon‐coated glass substrate, to perform the deprotection. The crude product was recovered with 70‐μL HPLC mobile phase (ethylenediaminetetraacetic acid (1mM), acetic acid (50mM), ascorbic acid (0.57mM),
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1% EtOH) and purified with reversed‐phase analytical‐ scale HPLC (Phenomenex Luna C18 column, 5 μm, 250 × 4.6 mm) at a flow rate of 1 mL/min. Purity of the purified product was verified using the same radio‐HPLC conditions. The enantiomeric purity was verified with analytical‐scale HPLC (Crownpack CR(+) column, 5 μm, 150 × 4 mm) using a mobile phase of HClO4 solution (pH = 2) at a flow rate of 0.8 mL/min. Results Initially the fluorination reaction was optimized by varying temperature (80‐140°C) and time (5‐10 min). We found out that the fluorination yield was increased significantly (from 5.1 ± 0.1% (n = 3) to 10.5 ± 0.6% (n = 3)) by adding the radical scavenger TEMPO.
TABLE 1 Performance of optimized microdroplet synthesis of [18F]FDOPA Performance (n = 3) Starting activity (MBq)
1.5 ~ 12.2
Synthesis time including purification (min)
~40
18
[ F]FDOPA conversion (%)
96 ± 0
Crude RCY (%)
20.5 ± 3.5
Isolated RCY (%)
15.1 ± 1.6
Enantiomeric purity (%)
98 ± 0
Total activity loss during overall synthesis (%)
50 ± 5
Unrecoverable activity on cover chip (%)
25 ± 0
Unrecoverable activity on bottom chip (%) Radioactivity recovery (%)
2±0 21 ± 4
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Then, we optimized base concentration, precursor concentration, and amount of TEMPO using a novel high‐throughput droplet reaction optimization platform and high‐throughput radio‐TLC readout method. The optimal conditions (100°C, 5 min, 8.4mM/4.1mM K222/ K2CO3, 9mM precursor, 75mol% TEMPO) resulted in a fluorination yield (as determined by radioactivity measurement and radio‐TLC) of 24.0 ± 2.0% (n = 3). The deprotection reaction was then optimized by varying type and concentration of acid, as well as reaction time and temperature. Overall performance is summarized in Table 1. Conclusion We have demonstrated the feasibility of synthesis of [18F]FDOPA in microliter‐sized droplets. The synthesis time was significantly shorter than the macroscale method (~40 min vs ~117 min, including purification),1 and utilized considerably less precursor (0.08 mg versus 12 mg). The isolated yield was comparable to the macroscale method (15.1 ± 1.6% (n = 3) vs 14 ± 4%), and improvements may be possible through further optimizations of the deprotection and purification steps. Reactions were performed starting with ~12 MBq of activity, but scale will be increased in the future by using an upstream [18F]fluoride concentrator4 to produce sufficient quantities for clinical imaging. ACKNOWLEDGMENTS We thank Prof. Stephen DiMagno for providing precursor for these studies, and are grateful for support from the NCI, NIA, and NIMH. R EF E RE N C E S 1. Kuik et al., J.Nucl.Med.56:106‐112,2015. 2. Wang et al., Lab.Chip.17:4342‐4355,2017. 3. Carroll et al., J.Fluor.Chem.128:127‐132,2007. 4. Hoover et al., Organometallics.35:1008‐1014,2016.
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-183 | Optimization of the copper mediated [18F]radiofluorination (CMRF) of arylstannane precursors using a “design of experiments” (DoE) approach Gregory Bowden1; Bernd Pichler2; Andreas Maurer1 1
Werner Siemens Imaging Center, Department of Preclinical Imaging and
Radiopharmacy, Eberhard Karls University Tuebingen, Germany; 2
Werner Siemens Imaging Center, Germany
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Introduction The development of CMRF chemistry has allowed unprecedented late‐stage access to radiofluorinated electron rich/neutral aromatic moieties.1 However, these multicomponent reactions are dependent on a number of critical experimental factors, which make their optimization difficult and time‐consuming through the traditional “one factor at a time” (OVAT) approach. DoE is a statistical approach to process optimization that is able to identify critical experimental parameters, factor interactions (when the setting of a factor effects the behaviour of another), and subsequently model the behavior of the process simultaneously across all reaction space with experimental efficiency.2 The aim of the described study was to use DoE to optimize the CMRF of [18F]p‐Fluorobenzyl Alcohol ([18F]pFBnOH) from an arylstannane in DMA with Cu (OTf)2 and pyridine and thus, assess the usefulness of DoE to radiochemical process development and research. Methods All experimental designs were constructed using MODDE Go 12 (Umetrics). In all runs, [18F]fluoride was trapped on QMA resin and eluted with 50 μg K2CO3, 10 mg KOTf in 550 μl H2O.1 Aliquots (250‐300 MBq) were transferred to V‐vials and dried azeotropically with acetonitrile under argon. Pre‐made reaction mixtures containing the necessary reagents (as required by the experimental design) were then added and left to stir under the required atmosphere and temperature for 15 min. Reactions were quenched with 1 ml of 0.25M HCl. Radiochemical conversions (RCCs) were assessed using radioTLC and product identity was confirmed using HPLC. Results A fractional factorial (RES V) “factor screening” DoE study, using 4‐tributyltin‐1,1′‐biphenyl (4.5 nmol) as a model substrate, was conducted to investigate the contribution of temperature (°C), solvent volume (μl), catalyst loading (eq), pyridine loading (eq) and atmosphere (air or argon) on RCC. The 24 runs (incl. 6 center points (CP)) were performed in 4 blocks of 6, which were added to the model as blocking factors to account for day‐to‐day variances in 18F processing. From the obtained data, a statistically validated multiple linear regression (MLR) model was fitted. The factor screening model suggested that temperature and solvent volume did not have a significant effect on RCC, while catalyst and ligand loading were significant factors. Interestingly, argon atmospheres had a slightly positive yet non‐significant influence on RCC, a result contrary to many literature‐published protocols which perform CMRF reactions under air. These results were used to
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construct a more detailed response surface optimization (RSO) study using a Box‐Behnken experimental design (15 runs incl. 3 CP) for the synthesis of [18F]pFBnOH. The amount of p‐tributyltin‐benzyl alcohol precursor (μmol), as well as the catalyst (eq) and pyridine (eq) loading, was varied in each run according to the pre‐designed experimental matrix (Figure 1, A), B)). A valid MLR model (R2 = 0.96 (observed % variance), Q2 = 0.86 (predicted % variance)) of the experimental output revealed a factor interaction between substrate pyridine loading. From the regression model, a response surface was generated which was used to estimate the optimal reaction conditions: precursor (25 μmol), catalyst (4 eq) and pyridine (5 eq) in DMA 700 μl at 110°C. Under these conditions the RCC was 58 ± 5.3% (n = 4), suggesting a useful model of the system that afforded better (albeit lower than predicted by the response surface) RCCs than previously obtained in our laboratory (Figure 1, C)). Conclusions DoE is a powerful approach to radiochemical reaction optimization that has the potential to reveal new insights into the behaviour of new 18F chemistry. It was used to show which experimental factors were most important to a model CMRF. It was also used to optimize and predict the experimental factors that will aid in the development of improved syntheses for novel tracers currently under development. Further work is currently being done to apply this approach to a number of novel
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tracers that have up until now suffered from low yields and poor synthesis performance.
RE FER EN CES 1. Makaravage, K. J. et al. Org. Lett. 18, 5440–5443 (2016). 2. Murray, P. M. et al. Org. Biomol. Chem. 14, 2373–2384 (2016).
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-184 | Radiochemical and analytical aspects of inter‐institutional quality control measurements on radiopharmaceuticals Erik de Blois1; Zanger Zanger2; Ho Sze Chan3; Mark Konijnenberg1; Wouter Breeman4 1
Erasmus MC, Netherlands; 2 TNO, Netherlands; 3 AlfaRim Medical
Holding BV, Netherlands; 4 Erasmus University Medical Center, Netherlands
Background Clinically applied radiopharmaceuticals have to meet quality release criteria like a high radiochemical yield and radiochemical purity. Many radiopharmaceuticals
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do not have marketing authorization and have no dedicated monograph within the European pharmacopeia, therefore general monographs on quality control have to be applied for clinical applications. These criteria require standardization and validation in labeling and preparation, including QC measurements according to well‐defined standard operation procedures. QC measurements however, are often based on detection techniques specific for a certain LC‐system. Multi‐institutional research and development of new radiopharmaceuticals lead to an increase in multicenter trials. Although all institutes’ radiopharmacies are using the same standardized labeling and operation procedures, they often use different LC and radiodetection systems. Here we present a comparison of QC assessments for 3 radiopharmaceuticals with focus on the interpretation of chromatograms, data‐output and potential differences in local practical performances of QC on (U)HPLC. Methods QC assessments for [111In]In‐CCK, [68Ga]Ga‐Bombesin and [177Lu]Lu‐PSMA analogs were compared. Two of the radiopharmaceutical QC assessments were also applied in other institutes using their own HPLC‐ systems and concordant software. Data from the HPLC‐injections and measurements is processed and summarized in chromatograms, based on a variety of smoothing algorithms for which different software programs are applied. Described radiopeptides were labeled and analyzed according their standardized labeling and operation procedures. Results Integration of main peaks on chromatograms resulted in a range of RCP, depending on the smoothing algorithm used. [111In]In‐CCK(A), 68Ga‐Bombesin(B), and [177Lu] Lu‐PSMA(C) analogs had a RCP range of 88%‐96%(A), 89‐95%(B), and 92‐99%(C), respectively. Important factors affecting final RCP value were site specific background radiation‐levels, intrinsic system properties such as noise and sensitivity, personal interpretation, e.g., peak‐tailing, and smoothing algorithms. Conclusion Measurement of RCP shows a strong method‐ and system‐dependency, even when parameters are validated, standardized and SOP are followed. Release criteria are frequently based on RCP data from one central location. The lack of interinstitutional validation and standardization in RCP determination makes the results therefore rather arbitrary. For multicenter
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trials, we recommend to compare locally determined RCP under validated and standardized conditions of in‐line activity detection between institutes for each radiopharmaceutical.
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-185 | iMiLAB: A new cassette‐based micro‐ fluidic platform for PET radiotracer synthesis —Initial results for the synthesis of [11C] methionine Francesca Goudou1,2,3; Abdul Karim Haji Dheere1,3; Antony Gee1,3; Virginie Hourtane2; Nicolas Masse2; Yahya Cisse2 1
King's College London, UK; 2 PMB, France; 3 Synbiolab, France
Objective Microfluidic‐based radiochemistry has several potential advantages for radiotracer synthesis including accelerated reaction rates, simple purification processes, high yields, high molar activities and one‐use disposability/ease of use.1 However, despite prompting the interest of the scientific community, few of these systems have been developed as commercially available products.1 PMB have developed a new microfluidic PET radio‐synthesis system, iMiLAB. An evaluation of iMiLAB performance is underway. [11C]methionine is widely used in clinical PET for imaging tumors and was therefore selected as one of the initial radiotracers for iMiLAB proof‐of concept studies.2 Here we report the initial results for the synthesis of [11C] methionine. Methods For test irradiations, [11C]CO2 was produced by the 14N (p, α)11C reaction using 11.5 MeV protons at 5 μA for 1.5 min. [11C]CH3I was produced by the gas phase method. L‐homocysteine (2 mg) was dissolved in 500 μL of 0.5 M NaOH in 1:1 (v/v) ethanol and water (vial 5). The precursor was loaded onto a C18 solid phase matrix embedded in a disposable iMiLAB microfluidic cassette (Scheme 1) by applying a pressure of 450 mbar for 3 minutes. Scheme 1. Schematic diagram of the microfluidic cassette used in R&D
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radio‐synthesizer iMiLAB. [11C]CH3I was delivered into the cassette (isotope port, flow rates: 30 mL/min or 15 mL/min) and reacted with L‐homocysteine to produce 11C‐methionine. This product was eluted with 2 mL of 0.1 M NaH2PO4 buffer (vial 6, loaded with 450 mbar, 3 min) to the formulation chamber. 10 mL of NaCl 0.9 % (vial 7, loaded with 350 mbar, 1.5 min) was used to formulate the radiotracer and the solution was transferred via the syringe port over a connected sterile filtration matrix (0.22 μm) under 300 mbar for 5 minutes to an external vial. Authenticity and radiochemical purity of the product was evaluated using an HPLC equipped with UV and radio detection. Results The radiotracer was produced within 13 minutes (from end of [11C]CH3I delivery) with a radiochemical purity of 99.9% at the end of synthesis. Initial [11C]CH3I flow rate studies revealed an increase in radiochemical yield (RCY) from 31% to 66% (decay corrected to end of [11C] CH3I delivery) when the [11C]CH3I flow rate was reduced from 30 mL/min to 15 mL/min. Conclusion Initial testing of the radiosynthesis of [11C]methionine has been performed on a new microfluidic PET radio‐synthesis system. Further process optimisation is in progress. The iMiLAB microfluidic cassette system is also being tested with a number of other 11C‐, 18 F‐, and 68Ga‐labelled radiotracers showing promising results.
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RE FER EN CES 1. Jian‐ping Z, Yong‐ping Z, Ming‐wei W and Ying‐jian Z. Chinese Journal of Nuclear Medicine and Molecular Imaging. (2012). 32, 315 – 318 2. Lodi F, Malizia C, Castelluci P, Cicoria G, Fanti S and Boschi S. Nuclear Medecine and Biology. (2012). 39, 447‐460.
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-186 | Large‐scale continuous‐flow production of [18F]DCFPyl on a microfluidic synthesis module Alex Poot1; Dion van der Born2; Sjoerd Eeden1; Danielle Vugts1; Albert Windhorst3; Kaspar Koch2 1
Amsterdam UMC, VU University, Netherlands; 2 Future
Chemistry Holding B.V., Netherlands; 3 VU University Medical Center, Netherlands
Objectives The GMP production capacity for PET tracers is often limited by hot cell capacity. Ideally, these products should be produced multiple times per day, like for instance the PSMA tracer [18F]DCFPyL. To increase the production capacity, the automated synthesis,
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cleaning and preparation for a next production offered by a microfluidic synthesis module is attractive.1–4 Unfortunately, the quantities of PET tracer produced using microfluidics are often rather low. The aim of this project was to develop a radiochemistry methodology based on a microfluidic synthesis module to synthesize [18F]DCFPyl in up to 10 GBq of product at end of synthesis per run in a fast, reliable and automated fashion. Ultimately the goal is to perform multiple productions per day in the same synthesis module to improve production capacity. Methods [18F]F− was obtained in a solution of 7.5 mM TBAHCO3 (ABX, Radeberg, Germany) and dried by azeotropic distillation with acetonitrile. Both [18F]F−/TBAHCO3 and DCFPyL precursor (custom synthesized) in dry acetonitrile were simultaneously infused into microreactor 1, where they are mixed and led through the reactor at 90°C with a 30‐second residence time. The outward flow of microreactor 1 was directly infused into microreactor 2, where it was mixed with concentrated H3PO4 for the hydrolysis of the protecting groups at 120°C with a 30‐second residence time. Reaction mixtures were analyzed by radioHPLC and TLC to determine the radiochemical formation of [18F]DCFPyl, these results were used for the optimization of the reaction conditions. At the optimal reaction conditions, the product was purified by semi‐preparative HPLC utilizing an Atlantis T3 ODB column (Waters, Etten Leur, The Netherlands) and 90/10/0.1 v/v acetonitrile/water/TFA as eluent at 4 mL/min.
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Results and discussion For reaction optimization purposes 200 MBq of [18F]fluoride was used. Fluorination was investigated at 75°C, 90°C, and 120°C for 30 seconds resulting in a TLC yield of 66, 95, and 0% respectively. Concentrated H3PO4 was used for the hydrolysis of the protecting groups, which was reacted at 60°C and 120°C for 30 seconds or at 90°C and 120°C for 60 seconds. Deprotection was most successful when reacting at 120°C for 30 seconds with an HPLC yield of 68%. Other conditions resulted in no deprotection or the formation of side products. Using optimal conditions as described before, a batch of [18F]DCFPyl was produced starting with 80 GBq of [18F]fluoride yielding 11.4 GBq product (radiochemical yield of 14%, N = 1). The radiochemical purity of 92.4% and molar activity was >20 GBq/μmol. TLC analysis of [18F]DCFPyl however showed a large amount of 15‐40% free fluoride. Conclusions This work demonstrates that 18F‐labeled products can be produced in a short reaction time and in a high yield using a microfluidic synthesis module. Up to 11 GBq of [18F]DCFPyl was produced. Current focus is on improving the HPLC purification towards higher purity of [18F]DCFPyl and multiple runs per day. RE FER EN CES 1. Pascali G et al., Nat. Prot., 2014, 9, 2017 2. Collier TL et al., Beilstein J Org Chem. 2017, 13, 2922 3. Matesic L et al., Nucl. Med. Biol., 2017, 52, 24 4. Kimura H et al., PLoS One, 2016, 11, e0159303.
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Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-187 | Fully Automated MPLC‐based manufacturing process and evaluation of potential stabilizers for flortaucipir F 18 injection Junichi Ogikubo; Robin Ippisch; Kuo‐Hsien Fan; Nathaniel Anthony Lim; Tyler Benedum Avid Radiopharmaceuticals, Inc., a wholly owned subsidiary of Eli Lilly and Company, USA
Objectives Flortaucipir F 18 Injection is currently manufactured using radiosynthesizers equipped with either non‐disposable1 or disposable fluidic pathways and a semi‐preparative HPLC purification column. An alternative method using solid phase extraction (SPE) cartridge‐ or medium pressure liquid chromatography (MPLC) column‐based purification with disposable fluidic pathways was investigated to develop a simpler, faster and higher yielding Flortaucipir F 18 Injection manufacturing process. In addition, several potential stabilizers were evaluated to determine their ability to stabilize Flortaucipir F 18 Injection batches with high radioactivity concentrations. Methods Various combinations of SPE cartridges or MPLC columns and mobile phase compositions were evaluated. SPE cartridges evaluated were found to be ineffective for purification. Upon identification of the appropriate MPLC purification condition, each step of the manufacturing process (i.e., [18F]fluoride isolation and processing, radiofluorination, protecting group removal, and formulation) was evaluated and optimized for maximum efficiency and simplicity. The resulting process
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was then subjected to a series of robustness studies including scale‐up with up to 444 GBq starting [18F]fluoride activity. Additionally, a variety of potential stabilizers (e.g., air, sodium ascorbate, monothioglycerol (MTG), and cysteine) was evaluated for their ability to stabilize Fortaucipir F 18 Injection with radioactivity concentrations up to approximately 8 GBq/mL. Results An MPLC‐based Flortaucipir F 18 Injection manufacturing process using the ORA NEPTIS® Perform radiosynthesizer was developed. Among the combinations of MPLC columns/SPE cartridges and mobile phases evaluated, an acidic ethanol‐saline mobile phase on a Teledyne ISCO RediSep® Rf Reversed‐Phase C18 MPLC cartridge was determined to be the optimal purification system. Additional modifications were made in various steps of the manufacturing process to further simplify the process and improve overall robustness. The final MPLC process (30 minutes total synthesis time) consistently produced batches with decay‐corrected radiochemical yields of 55‐65%, radiochemical purity of no less than 98%, and specific activity of up to 53 GBq/μg regardless of the batch scale (7.40 GBq ‐ 233 GBq). In addition, product having a radioactivity concentration of 3700 MBq/mL was stable when formulated with either 0.1% (w/v) cysteine or 0.05% (v/v) MTG. Conclusions An MPLC‐based process offers a faster, simpler, and higher yielding alternative to the existing Flortaucipir F 18 Injection manufacturing process and provides large batch sizes with high radiochemical purity. In addition, the large batch sizes with high radioactivity concentrations are stable when formulated with either 0.1% (w/v) cysteine or 0.05% (v/v) MTG.
RE FER EN CE 1. Attardo, G.; Lister‐James, J.; Lim, N. A. C.; Xiong, H. Patent WO 2015/047902 A1, 2015.
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P o s t e r C a t e g o r y : Au t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De v e l o p m e n t P-188 | Improved Florbetapir F 18 Injection manufacturing process Wei Zhang1; Aldo Cagnolini2; Xuan Huang1; David Pham1; Chaofeng Huang1; Nathaniel Anthony Lim1; Tyler Benedum1 1
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higher yielding manufacturing process (45 minutes total synthesis time with decay corrected radiochemical yields of 35 to 57%). Process 2 affords larger batch sizes (approximately 148 GBq from 370 GBq of [18F] fluoride starting activity) and higher radiochemical purity (no less than 99%) compared to Process 1, which is limited to less than 60 GBq of product with decay corrected radiochemical yields of 24% to 35% in 70 minutes total synthesis time.
Avid Radiopharmaceuticals, Inc., a wholly owned subsidiary of Eli Lilly
and Company, USA; 2 Avid Radiopharmaceuticals, Inc., a wholly‐owned subsidiary of Eli Lilly and Company, USA
Objectives To develop a simpler, more robust and reliable Florbetapir F 18 Injection manufacturing process using the ORA NEPTIS® Perform radiosynthesizer compared to the initial manufacturing process on the ORA NEPTIS® Plug radiosynthesizer (“Process 1”).1 Methods Previously, the direct correlation between the amount of precursor (AV‐105) used in the manufacturing process and the observed yield was reported.2 Evaluation of precursor amount as well as [18F]fluoride activity isolation and processing, 18F‐fluorination, protecting group removal, SPE isolation, HPLC purification, and formulation were further evaluated to increase radiochemical yield and batch sizes. The resulting individual optimized conditions were then applied to the manufacturing process using the ORA NEPTIS® Perform radiosynthesizer. A series of robustness studies, including scale‐up using up to 370 GBq of starting [18F]fluoride activity were performed. Results The development studies demonstrated that shortening both the [18F]fluoride activity dry down procedure (6.5 versus 9 minutes for Process 1) and protecting group removal condition (3M HCl, 120°C for 0.5 minutes versus 5 minutes for Process 1) did not affect the yield and shortened the manufacturing process. As noted previously, higher amount of precursor resulted in increased 18 F‐fluorination. Among the HPLC column types and mobile phase compositions evaluated, an ethanol based eluent on a Waters XBridge column was determined most suitable for purification effectiveness and efficiency. The combined conditions above resulted in an improved Florbetapir F 18 Injection manufacturing process (“Process 2”) using an ORA NEPTIS® Perform radiosynthesizer that is capable of consistently producing at least 148 GBq batches with decay‐corrected radiochemical yields of 35% to 57% (specific activity ranging from 5 to 80 GBq/μg and radiochemical purity no less than 99%). Conclusions Process 2 using an ORA NEPTIS® Perform radiosynthesizer is a simpler, more robust, shorter and
RE FER EN CES 1. Lister‐James, J.; Pontecorvo, M.J.; Clark, C.; Joshi, A. D.; Mintun, M. A.; Zhang, W.; Lim, N.; Zhuang, Z.; Golding, G.; Choi, S. R.; Benedum, T. E.; Kennedy, P.; Hefti, F.; Carpenter, A. P.; Kung, H. F.; Skovronsky, D. M.; Semin. Nucl. Med. 2011, 41, 300‐304. 2. Zhang, W. Lim N. C.; Cagnolini, A; Jackson, R. N.; Kielt, A. M.; MacNeill, D.; Lister‐James, J. Abstracts of Papers, 19th International Symposium on Radiopharmaceutical Science, Amsterdam, the Netherlands, August 28 ‐September 2, 2011; P‐439.
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t P-189 | Toward automation of a new process of dry nucleophilic [18F]fluoride production from [18F]triflyl fluoride Nnicolas Maindron1; Yyoann Joyard2; Vincent Tadino3; Anna Pees4; Albert Windhorst5; Danielle Vugts4 1
ORA, Belgium; 2 OOC, Belgium; 3 ORA Neptis, Belgium; 4 Amsterdam
UMC, VU University, Netherlands; 5 VU University Medical Center, Netherlands
Objectives A new fast and reliable process to deliver dry nucleophilic [18F]fluoride with efficient yield (≥90%) has recently be reported.[1] The method relies on the formation of gaseous [18F]triflyl fluoride from N‐phenyl‐bis (trifluoromethanesulfonimide) 1, and it overcomes the time consuming azeotropic drying step. Indeed, dry [18F] fluoride can be obtained within 5 minutes after eluting [18F]fluoride from the anion‐exchange cartridge. In this work, this methodology has been implemented for the first time on a Neptis® automated synthesizer. Afterwards, a new automated module dedicated to the production of dry [18F]fluoride from [18F]triflyl fluoride will be designed. Methods Reported conditions were first tested on non‐proprietary disposable cassettes used on Neptis® modules according to scheme 1. All the vials used were flat‐bottom 8‐mL glass reactors equipped with a silicone cap and a polyimide tube for the inlet (FDG Mx vial). [18F]fluoride was trapped onto
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a carbonated QMA cartridge (46 mg, Waters), then eluted to reactor 1 with 500 μL of an aqueous solution of 0.1M K2SO4. Tubing and the QMA cartridge were rinsed with 850 μL of DMF directly into reactor 1, filled with a 0.1M solution of 1 in DMF (150 μL, 0.015 mmol). Gaseous 2 was formed and distilled simultaneously by heating reactor 1 at 50°C with 30 mL/min nitrogen flow. Compound 2 was transferred to reactor 2 containing a trapping solution (KHCO3/K222, 0.040 mmol for each reagent, in TABLE 1
CH3CN or CH3CN/DMF 1/9, 1500 μL). [18F]triflyl fluoride was decomposed to provide dry [18F]fluoride. Afterwards, various precursor solutions (500 μL, in CH3CN or DMF) were automatically added to reactor 2 in order to evaluate the labelling efficiency. Crude reaction mixtures were analyzed by radio‐TLC. Results and discussion Three common tracer precursors were radiolabelled according to the method described above on a Neptis®
Results of the new process of [18F]fluoride production carried out on a Neptis® module
[18F]FDG
[18F]FMISO
[18F]MPPF
Precursor amount
25 mg in CH3CN
10 mg in CH3CN
10 mg in DMF
Trapping solvent
CH3CN
CH3CN
CH3CN/DMF 1/9
Activity trapped/Starting activity
86%
90%
70%
Remaining activity in RV1 (EOS)/Starting activity
2%
3%
5%
Molecule
Bulk activity (EOS)/Starting activity
79%
81%
61%
Labelled compounds in the bulka
92%
79%
36%
Radiolabelling yieldb
72%
64%
22%
Note. All the measurements done to calculate the ratio are not decay corrected. EOS: end of synthesis. a
Determined by radio‐TLC.
b
The synthesis was stopped after the labelling step.
For all experimented conditions, [18F]triflyl fluoride is formed with excellent yield (95‐98%; determined by measuring the residual activity at EOS in reactor 1). Trapping/decomposition of [18F]triflyl fluoride in the CH3CN/KHCO3 solution was efficient (86‐90%; ratio of the activity in reactor 2 at end of distillation and the starting activity). It should be noticed that trapping in CH3CN/DMF was slightly less efficient (70%). Optimizations are currently in progress to increase trapping yields (screening of flow rate, base amount, reactor geometry). Radiolabelling yields obtained are in accordance with the ones achieved with standard methods (azeotropic distillation).
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module with the kit configuration of Scheme 2. Results are summarized in Table 1. Conclusion First automation of [18F]fluoride production from [18F] triflyl fluoride has been successfully developed on a Neptis® module. Optimization of this process is currently in progress and might enable us to further improve radiochemical yields. 1. Pees et al., Chem. Commun., 2018, 54, 10179‐10182 (DOI: https:// doi.org/10.1039/C8CC03206H).
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-190 | New self‐cleaning module for implementing process development and automation in 18F‐radiochemistry Nnicolas Maindron1; Yyoann Joyard2; Vincent Tadino3 1
ORA, Belgium; 2 OOC, Belgium; 3 ORA Neptis, Belgium
Objectives Optimizing the radiosynthesis of a promising fluorine‐18 PET tracer for clinical trials and/or production is a time‐consuming and expensive process. It requires to use one cassette for every development test if a cassette‐ based radiosynthesizer is used, or to spend time to clean up the module if a kit‐less module is used. For radiation
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safety reasons, it is also not allowed to perform more than one or two radiosynthesis per day on the same module, thereby increasing the development time. In order to circumvent these drawbacks and speed up the optimization process ORA has developed a new automated kit‐less and self‐cleaning module (Scheme 1). Methods The new radiosynthesizer, called NEPTIS® xSeed, is equipped with a fully‐automated cleaning and drying system which can be set up outside the hotcell. The automatic cleaning module, that use four solvent bottles (K2CO3 50mM, CH3CN, EtOH, H2O), allows an efficient reconditioning of the QMA cartridge and fluid pathways. Thus, multiple runs can be performed in a day by one operator without opening the hot cell. The operator is then free to play on different parameters (drying, labelling time, temperature). With its 4‐position eluent block, composition of eluent for fluorination can be easily adjusted. xSeed module has also been designed to fit closely with the cassette‐based modules NEPTIS® Perform and mosaic‐RS to make the transfer from a kit‐less to a kit‐based radiosynthesizer as easy as possible. NEPTIS® kit‐based systems are widely used routinely worldwide to produce GMP batches of various fluorine‐18 PET tracers. Results As a proof of concept, new xSeed sequences were elaborated, allowing production of 4 [18F]‐FDG doses on the same day without opening the hot cell. Optimization of yields was easily achieved in a short time period. Same operations were carried out on others tracers:
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Radiotracer [18F]‐FDG quad Optimized [18F]‐FDG quad 18
[ F]‐DOPA Optimized [18F]‐FDOPA 18
[ F]‐PBB3 [18F]‐PBB3 18
XSeed RCY (%, ndc)
Perform/RS RCY (%, ndc)
52 (n = 10)a
52‐55 (single run)a
61 (n = 6)a
NA
b
54b
66b
NA
50
50
60
61
b
20b
54
[ F]‐MPPF
18
[18F]‐FMISO
48b
58b (estimated)
[18F]‐Choline
14a
20a
a
Isolated yield determined by measuring final activity with a dose calibrator.
b
Yield determined after labelling from Bulk mixture (activity of Bulk x Radio‐TLC purity x Radio‐HPLC purity).
Complete cleaning of module and reconditioning of QMA cartridge was performed between each radioactive run without affecting next production. Radiochemical yields and QC were in accordance with routine production performed on commercial modules. Improvements of current radiosynthesis (e.g., FDG, FDOPA, PBB3) have been achieved and new methods easily transferred back to existing NEPTIS (e.g., PBB3)
Conclusion xSeed is a new cost effective, kitless, and self‐cleaning module that can bridge the gap in [18F]‐tracer development. Examples of radiosynthesis development have been successfully carried out. Results obtained validate efficiency and reproducibility of the cleaning and reconditioning system. Sequence configurations developed on XSeed module can easily be implemented on NEPTIS® modules with disposable kits (and vice versa) simplifying the transition from research to GMP production.
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-191 | Synthesis of [11C]PK11195 and [11C] Ro15‐4513 using a cassette‐based method
syntheses to reduce the risk of cross‐contamination. PK11195 and Ro15‐4513 are carbon‐11 labelled radiotracers commonly used for neuroimaging. The tracers are typically synthesised to GMP standard using integrated synthesisers. We hereby report an automated cassette‐ based method for the radiosynthesis of [11C]Ro15‐4513 and [11C]PK11195. Method A Trasis AiO module with 18 valves was used for the synthesis of [11C]PK11195 and [11C]Ro15‐4513. Both radiotracers use a similar automation sequence and set‐up.1 For the synthesis of [11C]PK11195, desmethyl precursor and KOH were dissolved in DMF, gas phase‐produced [11C]CH3I was added to the mixture and allowed to react at room temperature for 5 minutes. [11C]Ro15‐4513 was synthesised using the desmethyl precursor and TBAI dissolved in DMSO. [11C]CH3I was added and the resulting mixture was heated at 80°C for 2 minutes.2 The mixtures were purified using semi‐preparative HPLC, formulated and sterile filtered. Results 2.1 GBq (RCY of 32 % d.c.) and 0.6 GBq (RCY of 19.7%) of [11C]Ro15‐4513 and [11C]PK11195 were produced starting from 20 GBq and 10 GBq of [11C]CO2, respectively. RCPs were >95%, and total synthesis times for both radiotracers, including [11C]CH3I production, purification, and formulation, were ∼34 minutes from EOB. Conclusion A robust GMP compliant cassette‐based method has been successfully developed for the radiosynthesis of [11C] PK11195 and [11C]RO15‐4513. The synthesis set‐up is simple, efficient, and requires a minimum of staff training. Furthermore, the process eliminates the need for cleaning at the end of synthesis. RE FER EN CE 1. Similar sequence except for reaction temperature 2. Precursors are purchased from ABX
Poster Ca tegory: A u t o m a t i o n / M i c ro f l u i d i c s / P r o c e s s De velo p men t
Abdul Karim Haji Dheere; Antony Gee; Mitja Kovac King's College London, UK
Objective There is an increased demand for the use of cassette based methods for manufacturing clinical radiotracers. One‐use, disposable cassettes are attractive from a GMP compliance perspective compared to integrated synthesisers as the latter require rigorous cleaning in‐between concurrent
P-192 | Use of a novel high‐throughput microdroplet reaction platform for rapid optimization of [18F]fallypride synthesis conditions Alejandra Rios1; Jia Wang1; Philip Chao1; R. Michael van Dam2 1
UCLA, USA; 2 UCLA Crump Institute for Molecular Imaging, USA
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Background During the development of novel tracers for positron emission tomography (PET), synthesis optimization is hindered by practical limitations on the number of experiments that can be performed per day (e.g., high cost of equipment and contamination of apparatus after use). Optimization and tracer development could be greatly accelerated by a platform that can enable rapid screening of multiple parameters in parallel (reaction time, temperature, reagent concentration). Here, we describe a proof‐ of‐concept parallel reaction platform that leverages the advantages of droplet microfluidic radiosynthesis including compact system size, reduction of reagent consumption, and the ability to achieve high molar activity even when using low starting radioactivity.[1] We then use this platform to perform a microdroplet synthesis optimization for [18F]fallypride, a neuroimaging tracer for dopamine D2/D3 receptors. Methods We built a four‐heater setup (Figure 1A), and fabricated microfluidic chips with 2x2 and 4x4 reaction sites (Figure 1D,1E), providing the capability to perform 16 to 64 reactions simultaneously. The Teflon‐coated silicon
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microfluidic chips (25 mm × 27.5 mm) were fabricated using photolithography to define arrays of circular hydrophilic regions acting as liquid traps for independent reactions.[2] Temperature uniformity was assessed via thermal imaging (FLIR T440‐25). To test for cross‐ contamination, different patterns of droplets of [18F]fluoride and DI water were deposited and heated at 105°C for 1 min, and the chip was imaged via Cerenkov imaging after drying. Synthesis of [18F]fallypride in droplets was carried out according to the process in Figure 1F. Variation of individual parameters (volume of precursor, TBAHCO3 concentration, and precursor concentration) was carried out (n = 2 replicates each) to determine their influence on fluorination efficiency and crude radiochemical yield (RCY). Volume of precursor was varied from 2 to 8 μL, TBAHCO3 concentration was varied from 0.95 mM to 60 mM, and precursor concentration ranged from 0.6 mM to 77 mM. Performance of synthesis was evaluated with a calibrated dose calibrator and radio‐TLC. To accelerate analysis, radio‐TLC plates were spotted with multiple samples (up to 8) before developing with 90% methanol and 10% DI water mobile phase and were read out via a new Cerenkov imaging approach.
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Results Temperature uniformity of the heaters was high, with only minor areas around the heater edges that deviated more than 2% from the average temperature (Figure 1B). Cerenkov images revealed that no cross‐contamination to blank (DI water) sites occurred during the [18F] fluoride drying process (Figure 1D,1E). By examining the influence of multiple reaction variables (Figures 1G‐1I), the synthesis of [18F]fallypride was optimized to achieve high crude RCY and fluorination efficiency. The optimal precursor volume was 6 μL (crude RCY = 90 ± 1%, n = 4; fluorination efficiency = 98 ± 1%, n = 4), the optimal TBAHCO3 concentration was 30mM (crude RCY = 92 ± 1%, n = 2; fluorination efficiency = 99 ± 0%, n = 2), and the optimal precursor concentration was 38.5mM (crude RCY = 87 ± 3%, n = 2; fluorination efficiency = 96 ± 0%, n = 2). Conclusions The performance of radiochemistry processes and reactions exhibited high reproducibility among reaction sites. This suggests that the platform could be used to quickly optimize reactions (e.g., synthesis of [18F]fallypride) by enabling the exploration of multiple reaction conditions with multiple replicates in parallel. The ability to perform up to 64 reactions simultaneously gives a much more complete and thorough understanding of the influence of reaction parameters than is typically studied using conventional radiochemistry apparatus. An automated liquid dispensing and collecting system is being developed to automate the optimization process, thereby reducing radiation exposure and increasing experimental throughput. ACKNOWLEDGMENTS We are grateful for support from the NCI and NIMH for this work. R EF E RE N C E S 1. Sergeev et al., Commun. Chem. 1: 1‐10, 2018. 2. Wang et al., Lab Chip. 17: 4342‐4355, 2017.
Poster Category: A u t o m a t i o n/ M i c r o f l u i d i c s/ P r o c e ss Development P-193 | High‐throughput microdroplet radiochemistry platform to accelerate radiotracer development Jason Jones1; Alejandra Rios1; Philip Chao1; Jia Wang1; R. Michael van Dam2 1
UCLA, USA; 2 UCLA Crump Institute for Molecular Imaging, USA
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Introduction Conventional modules for the synthesis of PET tracers are generally designed to perform a single synthesis at a time, and to be operated once per day (e.g., requiring overnight radioactive decay to decontaminate the instrument). We believe the development of novel tracers could be greatly accelerated by adopting high‐throughput methods—as have long been used in drug development —into this field. A high‐throughput radiosynthesizer would enable the rapid synthesis of multiple candidate compounds to facilitate evaluation of their suitability for imaging by measuring in vitro and in vivo properties[2] and would enable accelerated synthesis optimization to maximize yield and repeatability by performing reactions under many different conditions (with replicates) in parallel. Here, we develop an automated, high‐throughput robotic platform for performing dozens of parallel reactions, leveraging advantages of droplet radiochemistry[3,4] (i.e., minimal volume, high molar activity, fast reactions). While there is a commercial module (NanoTek, Advion) that can operate in an optimization mode, it is difficult to decouple some reaction variables in flow‐chemistry systems, and the system does not support synthesis of multiple compounds.[5] Methods To increase throughput of droplet reactions, we developed Teflon‐coated silicon microfluidic chips containing 2 × 2 or 4 × 4 arrays of individual hydrophilic reaction sites. An XYZ robotic gantry moves a set of non‐contact reagent dispensers and a pipette tip, to add reagents to individual reaction sites and to transfer liquids to or from microwells. To further increase throughput, multiple chip heaters are incorporated (each composed of a ceramic heater with integrated thermocouple, cooling fan, and temperature controller) to allow 4 chips to be operated in parallel. Results The overall size of the system is 64×41×56 cm3, allowing safe operation within a compact (von Gahlen) minicell. The actuators move at 400 mm/s (enabling movement between any two locations in 99% for both products).
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Conclusions The novel dual modality probe was successfully synthesized and labeled with 111In and 68Ga for respective SPECT/fluorescence and PET/fluorescence imaging studies. The two‐step radiolabeling method based on the orthogonal CBT/1,2‐aminothiol click reaction is very practical for regioselective labeling of N‐terminal cysteine‐ containing sensitive biomolecules. Further in vitro stability, biodistribution, and imaging studies of the CAIX‐ ligands are currently underway in our laboratory. ACKNOWLEDGMENTS We gratefully acknowledge the Leenaards Foundation (grant # 3699), NSERC, and Erasmus MC for financial support. R EF E RE N C E S 1. Kuil, J.; Velders, A. H.; van Leeuwen, F. W. Bioconjug Chem 2010, 21, 1709. 2. Culver, J.; Akers, W.; Achilefu, S. J Nucl Med 2008, 49, 169. 3. Chen, K. T.; Ieritano, C.; Seimbille, Y. ChemistryOpen 2018, 7, 256.
Poster C ate gory: Mu lti modal ity Imaging Probes/Nanoparticles P-218 | The diagnostic efficiency of Bombesin functionalized superparamagnetic iron oxide nanoparticles in in breast cancer mouse models Li Li; Huawei Cai; Lili Pan; Xin Li; Changqiang Wu; Rong Tian; Anren Kuang Department of Radiology & Nuclear Medicine, Erasmus MC, Netherlands
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Objectives The early and accurate detection afforded by imaging techniques has significant impact on mortality reduction of cancer patients. However, it is difficult to achieve satisfactory performance in tumor diagnosis using any single modality imaging method. Interest in multimodal imaging has continued to grow because an integrated approach may lead to synergistic benefits. Here, we designed and characterized a novel dual‐modality magnetic resonance imaging (MRI)/near‐infrared fluorescence imaging (NIRFI) nanoprobe and verified its feasibility in MDA‐MB‐231 tumor‐bearing nude mice models. Methods The nanoprobes were prepared by incorporating superparamagnetic iron oxide (SPIO) nanoparticles into DSPE‐PEG5K micelles to which a tumor‐targeted peptide (Bombesin, BN), and a NIRF dye (Cy5) had been conjugated. The characteristics of SPIO/DSPE‐PEG5K‐(BN&Cy5) were evaluated. The cytotoxicity, targeting specificity, and MR/NIRF multimodal imaging properties of SPIO/DSPE‐PEG5K‐(BN&Cy5) were examined in vitro and in vivo. Results The prepared nanoparticles displayed a well‐defined spherical morphology with a mean diameter of 145 ± 56 nm. The relaxivity value of the nanoparticles was 493.94 mM−1 s−1. Both in vitro and in vivo studies demonstrated the nanoparticles were non‐toxic and biocompatible contrast agents for cancer diagnosis. In MR imaging, the reduction of the T2 signal in the tumor by targeted probes was by 21.9% at 4 h post injection, whereas only a 0.3% (P < 0.05) decrease was observed in the non‐targeted group. NIRF imaging also showed
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that the imaging efficiency of targeted probes was much greater. Conclusions The novel MRI/NIRFI dual‐modality nanoprobes are promising contrast agents for the diagnosis of cancer.
Poster C ate gory: Mu lti modal ity Imaging Probes/Nanoparticles P-219 |
111
In‐radiolabeling of tri‐PEGylated porous silicon nanoparticles and their in vivo evaluation in murine 4T1 breast cancer model Dave Lumen1; Simo Näkki2; Surachet Imlimthan1; Elisavet Lambidis1; Mirkka Sarparanta1; Wujun Xu2; Vesa‐Pekka Lehto2; Anu Airaksinen1 1
University of Helsinki, Finland; 2 Pharmaceutical Physics, Department of
Applied Physics, University of Eastern Finland, Finland
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Objectives Polyethylene glygol (PEG) has been successfully used for improving circulation time of several nanomaterials, but so far, it has not been that successful in prolonging circulation of porous silicon (PSi) NPs. The aim of this project was to find the optimal radiolabeling method for tri‐ PEGylated mesoporous silicon nanoparticles (TPEG) and evaluate their in vivo behavior in 4T1 murine breast cancer allografts. Methods TPEG‐PSi NPs were prepared according to the literature1 and functionalized with trans‐cyclooctene (TCO) and bicyclo[6.1.0]nonyne (BCN) conjugates. Several different labeling strategies were tested. The modified particles were labeled either by reacting them with DOTA‐PEG4‐ Tz, followed by radiolabeling with 111InCl3 or radiolabeling them directly with [111In]DOTA‐PEG4‐Tz via click chemistry. DOTA‐PEG4‐tetrazine was synthesized from terazine‐PEG4‐amine and DOTA‐NHS ester
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in mild reaction conditions. Tetrazine and DOTA molecules were mixed with 2 mL DMF and 200 μL Et3N, and the reaction mixture was mixed overnight (RT). Product was purified by using semi‐preparative HPLC and evaporated to dryness yielding a red oil. The synthesized DOTA‐PEG4‐Tz was used for functionalization of the TCO and BCN‐conjugated particles with DOTA by incubating the particles (RT overnight), followed by purification with repeated centrifugations. The DOTA conjugated particles were labeled with 111In in 0.2M ammonium acetate buffer (pH = 6.8) (30 min at 37°C). Alternatively, DOTA‐PEG4‐Tz (8 μg) was first mixed in conical centrifuge tube with 0.5 mL ammonium acetate buffer solution (pH 6.8) and 111InCl3. The mixture was stirred gently 10min at 37 °C. [111In]DOTA‐PEG4‐Tz was purified by solid phase extraction (light C‐18 cartrigde). The TCO and BCN‐ conjugated particles were labeled with [111In]DOTA‐ PEG4‐Tz (30min at 37°C). Stability tests for 111In labeled particles were made in PBS and 10% mouse plasma. Based on the superior stability, the TCO‐conjugated, [111In] DOTA‐PEG4‐Tz labeled particles selected for the further evaluation. Biodistribution and tumor accumulation of the 111In‐labeled TPEG particles were determined in 4T1 allografted mice. [111In]TPEG (100μg in 200μl PBS) were administered intravenously. Ex vivo biodistribution of the particles was determined at 5 min, 1 h, 4 h, 24 h, and 48 h time points and SPECT/CT images were taken at 1 h, 5 h, and 24 h time points. The circulation half‐life of the particles was determined from blood samples collected at 5 min, 15 min, 30 min, 1 h, 4 h, and 24 h after administration. Tumor sections collected at the 1 h, 4 h, and 24 h time points were analyzed with real‐time digital autoradiography on the ai4r LeBeaver system. Results DOTA‐PEG4‐Tz was synthesized with 78 ± 2% yield (n = 3). Radiochemical yield for [111In]DOTA‐PEG4‐Tz was >99% when at least 8 μg of precursor was used. Direct 111In‐labeling to DOTA‐PEG4‐Tz conjugated TPEG particles gave higher labeling yields (50 ± 11%, n = 2), but the in vitro stability tests revealed significant release of 111In in 10% mouse plasma. When using [111In]DOTA‐ PEG4‐Tz to label TPEG‐BCN, the radiochemical yield remained low (13 ± 3 %) but with TPEG‐TCO, we were able achieve 40 ± 8% (n = 4) radiochemical yield. The in vitro stability of these particles was excellent, over 95% after 5 h in 10% plasma. The [111In]TPEG particles exhibited a typical biodistribution pattern with high uptakes in the liver and spleen (48.9 ± 6%ID/g and 34.2 ± 13 %ID/g at 24 h time point). Tumor uptake was only 0.30 ± 0.2%ID/g at the 24 h time point. Blood %ID/g were 15.79 ± 1.0 and 3.67 ± 2.7 at 5 min and 30 min time points, which are higher than typically observed for PSi nanoparticles, but the value decreased to 0.21 ± 0.1 at 4 h time point.
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Conclusions DOTA‐PEG4‐Tz was successfully synthesized and used as a precursor for 111In labeling. Radiolabeling of TCO conjugated TPEG particles gave 40 ± 8% RCY, and the stability of the particles were over 95% after 5 h in 10% plasma. It was found out that the limiting factor for the radiolabeling yield was the amount of available TCO on the surface of the particles. By increasing the number of TCOs on the particle surface, we could achieve a higher labeling yield. Biodistribution studies showed high liver and spleen uptake (24 h) but with slightly improved circulation in blood. ACKNOWLEDGEMENTS The project was funded by the Academy of Finland (298481) and the University of Helsinki. RE FER EN CES Näkki, S, et al, Acta Biomater. 2015, 13, 207−215
Poster Ca tegory: M ul timoda li ty I m agi n g P r ob es / Nan op ar t i cl es P-220 |
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Cu‐radiolabeled polymeric micellar nanoparticles for targeting EGFR in cancer
Stephanie Mattingly1; Igor Paiva2; Melinda Wuest3; Michael Weinfeld2; Afsaneh Lavasanifar2; Frank Wuest3 1
Department of Oncology, University of Alberta, Canada; 2 Faculty of
Pharmacy and Pharmaceutical Sciences, University of Alberta, Canada; 3
University of Alberta, Canada
Objectives Radiolabeling with radionuclides such as 64Cu (t1/ 2 = 12.7 h) for PET imaging represents an efficient way to monitor the biodistribution, stability, and clearance profile of nanoparticles (NPs) in vivo. We have developed a prelabeling approach where 64Cu, incorporated into a macrocycle complex, is conjugated to polymeric micellar NPs under mild, aqueous conditions. A targeting peptide, GE11, is employed to enhance the delivery of the NPs to highly proliferative cells overexpressing epidermal growth factor receptor (EGFR). Methods Polymeric micellar NPs were prepared using poly(ethylene oxide)‐poly(α‐benzyl carboxylate‐ε‐caprolactone) (PEO‐PBCL) by solvent evaporation.[1] EGFR targeting peptide GE11 (YHWYGYTPQNVI) was covalently attached to the surface of the micelles. 64Cu was incorporated into a NOTA (1,4,7‐triazacyclononane‐N,N′,N″‐ triacetic acid) chelator bearing aniline functionality
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suitable for nitrosation and conversion to a reactive diazonium salt.[2] Micelles were added directly to the prelabeled diazonium salt. Azo‐click coupling between the labeling building block and tyrosine residues on the targeting peptide produced a stable covalent linkage. Results Biodistribution of the 64Cu‐NOTA‐GE11‐micelles was assessed by PET imaging over 48 hours in normal BALB/c mice and showed desirable slow clearance from the blood pool (heart), negligible renal clearance, and steady accumulation together with delayed hepatobiliary clearance of the particles in liver and spleen as anticipated for intact larger nanoparticles (≈70 nm diameter). HCT116 human colon cancer cells, reported to overexpress EGFR, were used to grow subcutaneous tumors in NIH‐III mice. 64Cu‐NOTA‐GE11 NPs and, as a negative control, labeled micelles bearing mock peptide HW12, which does not target EGFR,[3] were compared for relative tumor uptake. PET data from the tumor bearing mice indicate that both EGFR targeting and nontargeting labeled NPs exhibit a long retention in the blood pool and tumor accumulation. A modest enhancement in accumulation was observed for the targeted (GE11‐ loaded) NPs as compared to the nontargeted (mock peptide) NPs. Differences in tracer uptake between the targeted and non‐targeted NP systems were easily observable at the 24 and 48 hours time points. Muscle retention over time was low and remained so over 48 hours. These
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results suggest that GE11 seems to have an effect on targeting of EGRF‐expressing tumors. Conclusions 64 Cu‐NOTA‐GE11 NPs are interesting cancer imaging agents exploiting a combination of specific (EGFR) and nonspecific (enhanced permeability and retention effect) targeting. ACKNOWLEDGEMENTS The authors gratefully acknowledge the Dianne and Irving Kipnes Foundation and the Alberta Cancer Foundation for supporting this work. RE FER EN CES 1. Garg S. M. et al. Biomaterials 2017, 144, 17‐29. 2. Leier S. et al. J. Label. Compd. Radiopharm. 2017, 60 (Suppl. 1): S94. 3. Mondal G. et al. Biomacromolecules 2016, 17 (1), 301‐313.
Poster Ca tegory: M ul timoda li ty I m agi n g P r ob es / Nan op ar t i c l es P-221 | Radioiodine labelled melanin nanoparticles for cancer brachytherapy Xinyu Wang; Junjie Yan; Min Yang Jiangsu Institute of Nuclear Medicine, China
Objectives Radioiodine therapy is widely used in cancer treatment. For example, 125I seed implantation is common for brachytherapy in solid tumor. 131I is most commonly used in the treatment of hyperthyroidism due to Graves' disease or a nodule in the thyroid gland. Melanin is a natural material with good metal chelating properties. Previously, we used it as metal carrier for photoacoustic and MR imaging, even for Fe overload treatment. Here, we report the use of melanin nanoparticles (MNP) as novel radioiodine carrier for brachytherapy. Methods The water‐soluble MNP were fabricated according to the previous study. Then 131I ions were labelled on MNP by chloramine T oxidation and new silver‐medium chelating, respectively. For the latter method, the silver ions were conjugated with MNP at first, then 131I ions were binding with silver in MNP to form AgI. The radiolabeling efficiency and stability were compared by TLC method. Results MNP can be radiolabeled with 131I through both methods. The radiolabeling efficiency of 125I is 31% and 78% individually. However, the MNP‐Ag‐1 131I obtained
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by silver ions precipitation exhibits much better stability in serum. After 24 h, 131I retained in MNP was still more than 95%. Instead, the stability of MNP‐131I obtained by chloramine T oxidation maintained barely 50%. The cancer killing ability of MNP–Ag–131I was proved in both PC3 cells and PC3 tumor bearing mice. Conclusions We developed a novel strategy for radioiodine labelling melanin nanoparticles. The Ag–I method for MNP radioiodine labelling has advantages including a fast labelling time, high labelling yield and high stability. The MNP–Ag–131I also exhibited good cancer‐killing ability both in vitro and in vivo. Research support: We thank financial supports from the National Natural Science Foundation (31671035, 51473071, 21504034), National Significant New Drugs Creation Program (2017ZX09304021), and Jiangsu Provincial Medical Innovation Team (CXTDA2017024).
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ Ca r di ol og y P-222 | Radiosynthesis of β‐phenylethylamine derivatives for cardiac sympathetic nervous PET imaging Yulin He; Jinming Zhang The PLA General Hospital, China
Abstract Imaging presynaptic and postsynaptic functions of the cardiac autonomic nervous system are important for the
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evaluation of cardiac damage. We synthesized and compared four radiolabeled β‐phenylethylamine derivatives for imaging purposes. [11C]‐N‐methylphenylethylamine ([11C] MPEA), [11C]‐N‐methylhydroxyphenethylamine ([11C]m‐ MTyr), [11C]‐N‐methyltyramine ([11C]p‐MTyr) and [11C]‐ N‐methyldopamine ([11C]MDA) were synthesized by aminomethylation. The biodistribution of the four radiolabeled compounds was initially evaluated in Kunming mice and validated in New Zealand white rabbits. The total synthesis time (including HPLC separation) of [11C]MPEA, [11C]m‐MTyr, [11C]p‐MTyr and [11C]MDA was about 30 min, 25 min, 25 min, and 30 min, respectively. The radiochemical yield of them was 25%, 13%, 33%, and 18%, respectively, and radiochemical purity was 99.11 ± 0.35%, 98.76 ± 0.45%, 99.06 ± 0.75%, and 99.36 ± 0.41%, respectively. [11C]MDA had good myocardial uptake (5.66 ± 0.35), which was significantly higher than the lung uptake (2.78 ± 0.03) at each time point. The heart‐lung and heart‐liver radioactivity uptake ratios were 2.07/1 and 1.75/1, respectively, at 10 min after injection. [11C]MDA PET/CT imaging in the New Zealand white rabbits showed a clear left ventricular image and radioactivity uniformly distributed in ventricular wall, while a right ventricular image developed partially. In contrast, the biodistribution results showed radioactivity uptake of [11C]‐MPEA, [11C] m‐MTyr, and [11C]p‐MTyr in the myocardium was lower than in the lung, liver, spleen, and kidney but was similar to that in the muscle. These results suggest that [11C]MDA has a good myocardial uptake and gets uniformly distributed in the left ventricular wall. It also has a higher target to non‐target ratio, making it suitable for nuclide myocardium imaging. Keywords b‐phenylethylamine; carbon‐11 labeling; cardiac sympathetic nervous; positron imaging agent
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ACKNOWLEDGMENTST his work was supported in part by a grant from National Natural Science Foundation of China (81660295) and Natural Science Foundation of Inner Mongolia (2016MS(LH)0812).
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ Ca r di ol og y P-223 | A 18F‐PET probe for detection of oxidative stress in doxorubicin induced cardiotoxicity Ran Yan King's College London, UK
Background Doxorubicin is routinely used in cancer chemotherapy. Its dose dependent cardiotoxicity is one of the most severe side effects causing symptomatic cardiomyopathy to about 10% of patients. The invasive right ventricle endomyocardial biopsy is the gold standard method to detect the Doxorubicin myocardial damage. Accumulating evidence indicates that reactive oxygen species (ROS) induced oxidative stress is the underlying pathogenesis of Doxorubicin cardiotoxicity. Thus, a ROS selective PET tracer for the non‐invasive measurement of myocardial oxidative stress is highly desirable for both early diagnosis and prognosis purpose.
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Methods and results We have designed a ROS sensitive molecular probe, 18F‐ ROS‐probe01. Its radiosynthesis was achieved with non‐ decay correct isolated radiochemical yields of 10 ± 3% (n = 10). 18F‐ROS‐probe01 showed rapid and selective oxidation by superoxide (around 60% in 5 min, n = 3) compared to other physiological ROS in vitro (Figure 1A). In addition, the 18F‐ROS‐probe01 superoxide oxidation can be partially inhibited to about 30% (n = 3) in the presence of ascorbic acid (1 mg/mL) (Figure 1A). When incubated 18F‐ROS‐probe01 with xanthine oxidase/xanthin/catalase in PBS at 37°C for 15 min, about 45% of 18F‐ROS‐probe01 was oxidized determined by radioHPLC (Figure 1B). Subsequently, 18F‐ROS‐probe01 was tested in a rat model of Doxorubicin‐induced cardiotoxicity using osmotic mini‐pumps to deliver a cumulative dose of 30 mg/kg Doxorubicin (n = 6) or vehicle control (n = 4) at a constant rate for 6 days. Quantitative PET data analysis showed that 18F‐ROS‐probe01 had two‐fold increased retention and a significantly higher (p < 0.05) left ventricle to myocardial blood pool uptake ratio in the hearts of Doxorubicin‐treated animals vs control (Figure 1C). Conclusions We have developed a novel radiotracer, 18F‐ROS‐probe01, for the direct detection of oxidative stress in Doxorubicin induced cardiotoxicity by PET. It is selectively towards superoxide oxidation. 18F‐ROS‐probe01 shows significantly increased myocardial retention in the Doxorubicin‐treated rats. These results warrant further optimization of 18F‐ROS‐probe01 for clinical translation.
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AcknowledgementWe would like to thank British Heart Foundation (PG/15/60/31629) to support this work.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ Ca r di ol og y P-224 |
18
F‐Py‐(cApoPep)2: Apoptosis‐targeting 18F‐labeled PET tracer for imaging of the vulnerable plaque
Sso Yyoung Chu1; Hyeon Jin Jeong1; Min Hwan Kim1; Mi Hyun Kim1; Jae Seong Kim1; Byoung Se Lee1; Hyo Eun Park2; Chan Woo Kim2; Joo Hyun2; Kiyuk Chang2; Dae Yoon Chi3 1
Futurechem, Republic of Korea; 2 The Catholic University of Korea,
fast clearance over time through urinary tract, and 2.26E‐ 02 ± 1.92E‐02 of effective dose (mSv/MBq). Conclusions Monomer, dimer, and trimer of cApoPep were synthesized and each labeled with F‐18. In vivo and ex vivo MicroPET/CT study exhibited fast background clearance and positive plaque images. RE FER EN CES 1. Wang K, Purushotham S, Lee JY, Na MH, Park H, Oh SJ, et al. In vivo imaging of tumor apoptosis using histone H1‐targeting peptide. J Control Release. 2010;148(3):283‐91. 2. Basuli F, Zhang X, Woodroofe C, Jagoda EM, Choyke PL, Swenson RE. Fast indirect fluorie‐18 labeling of protein/peptide using the useful 6‐fluoronicotinic acid‐2,3,5,6‐tetrafluorophenyl prosthetic group: a method comparable to direct fluorination. J Labelled Comp Radiopharm. 2017:60(3):168‐175.
Republic of Korea; 3 Department of Chemistry, Sogang University, Republic of Korea
Objectives Atherosclerotic cardiovascular disease is a leading cause of death and disability worldwide. Among a number of biological events in atherosclerotic plaque, we focused on apoptosis process of macrophage. The aim of this study is to evaluate apoptosis‐targeting 18F‐labeled PET tracers for imaging of the atherosclerotic plaque. Methods Apoptosis is a potential target of vulnerable plaques. From phase display, a peptide sequence of CQRPPR, named apoptosis‐targeting peptide‐1 (ApoPep), was found to have specific affinity for histone H1 on surface of apoptotic cells and nucleus of necrotic cells.(1) Results We first synthesized cyclic ApoPep (cApoPep) internally linked by disulfide bond between two terminal cysteins of CQRPPRC. Monomer, dimer, and trimer of cApoPep were prepared by using linear peptide spacers with different length, respectively. 18F‐Labeling was achieved by amide bond formation of amine group of cApoPeps and 6‐18F‐ fluoronicotinic acid 2,3,5,6‐tetrafluorophenyl ester (18F‐F‐ Py‐TFP), which was prepared by a nucleophilic aromatic 18 F‐fluorination of trimethylammonium precursor.(2) In vivo MicroPET/CT images were obtained after IV injection of each of the three different 18F‐Py‐ApoPep compounds to high fat‐diet ApoE mouse. Subsequently, the mouse was sacrificed and the aorta was dissected under microscope, and the ex vivo aorta‐PET was imaged. All of the 18F‐Py‐ ApoPep compounds showed rapid renal clearance and positive uptake in the aortic plaques but had no physiologic uptake in the myocardium and the brain. Biodistribution study with normal mouse and 18F‐Py‐(cApoPep)2 showed
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ C a r d i o l o g y P-225 | Optimization of the automated synthesis of [11C]mHED ‐ administered and apparent molar activities Chrysoula Vraka1; Verena Pichler2; Neydher Berroteran‐Infante1; Tim Wollenweber1; Anna Pillinger1; Lukas Fetty1; Maximilian Hohensinner1; Dietrich Beitzke; Xiang Li1; Câcile Philippe2; Katharina Pallitsch; Markus Mitterhauser2; Marcus Hacker1; Wolfgang Wadsak2 1
Department of Biomedical Imaging and Image‐guided Therapy, Division
of Nuclear Medicine, Medical University of Vienna, Austria; 2 Medical University of Vienna, Austria
Objective In the last decades, it was shown that [11C]meta‐ hydroxyephedrine ([11C]mHED) is one of the most promising PET tracers for imaging of cardiac innervation. The apparent disadvantage caused by the short half‐life of carbon‐11, was alleviated by several studies showing excellent pharmacokinetic properties of [11C]mHED. Moreover, its radiosynthesis is straight forward and has been reported with sufficient yields already in 1990. Since then, a handful of articles were published focussing on the optimization of the original synthesis described by Rosenspire et al,[1–4] where they reported increased radiochemical yields and reduced synthesis time. However, reproducibility and repeatability of the reported RP‐HPLC purification methods are not feasible due to the pH sensitivity of
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mHED. None of the published procedures improved the molar activity or the concentration of the residual metaraminol (precursor). Furthermore, no adequate purification process subsequent to HPLC separation was reported. In fact, it is known that metaraminol is also a substrate for the norepinephrine transporter (NET) and can therefore affect the apparent molar activity and consequently the imaging quality similar to effect by high amounts of “cold” mHED. To this end, this study aims at optimizing the synthesis and improving the applied concentrations of metaraminol and mHED in patients and animals. Methods The automated synthesis procedure was performed on a GE Tracerlab FX C Pro module using semi‐preparative RP‐HPLC for separation. For the mobile phase, a step gradient was utilized starting with 50/50 acetonitrile/water (v/v%) and switching to an acidic mobile phase (50/50 acetonitrile/0.004% H3PO4, conc (v/ v%)) after the elution of the precursor. The isolated product was then retained on a weak cation exchange cartridge and eluted with 3 mL of physiological saline (0.9%). Five Morbus Fabry patients underwent PET/MRI for detection of changes in sympathetic innervation. Additionally, μPET/CT was conducted in ten rats (ischemic model). For all individuals, absolute administered concentrations of precursor and mHED were calculated
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and correlated to the VOI myocardium/intra‐ventricular blood pool (Myo/ivBP) ratio. Statistical analysis was performed as pearson correlation (p‐value two‐tailed, confidence interval of 95%) using GraphPad Prism 6.01. Results The automated synthesis procedure was improved by achieving reliable separation through semi‐preparative RP‐HPLC and product purification and formulation in 3 mL of physiological saline. The radiochemical yield ranged from 1 to 7 GBq (mean 3 ± 2 GBq), the molar activity was 121 ± 98 GBq/μmol (24 to 446) with mHED and metaraminol concentrations of 4 ± 8 μg/mL and 8 ± 7 μg/mL, respectively (n = 32 syntheses). Within these applied mass ranges (sum of metaraminol and mHED in humans max. 20.5 μg and 9.5 μg in rats), neither a change in imaging quality nor any side effect in patients and rats were observed and no significant correlation was found (see Figure 1 left: animal study, p values > 0.05 and right: Morbus Fabry patients, p values > 0.2). Conclusion In summary, the optimized fully‐automated synthesis and purification method of [11C]mHED is easily applicable in other radiopharmaceutical departments and proved to be repeatable and reproducible over 50 syntheses. Moreover, it was shown that the administered molar activities and residual precursor concentration have a negligible direct effect on the imaging quality.
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R EF E RE N C E S 1. Någren K, Müller L, Halldin C, Swahn CG, Lehikoinen P. Improved synthesis of some commonly used PET radioligands by the use of [11C]methyl triflate. Nucl Med Biol 1995;22:235–9. 2. Lodi F, Rizzello A, Carpinelli A, Di Pierro D, Cicoria G, Mesisca V, et al. Automated synthesis of [11C]meta hydroxyephedrine, a PET radiopharmaceutical for studying sympathetic innervation in the heart. 2008 Comput. Cardiol., Bologna, Italy: IEEE; 2008, p. 341–3. 3. Dort MEV, Tluczek L. Synthesis and carbon‐11 labeling of the stereoisomers of meta‐hydroxyephedrine (HED) and meta‐ hydroxypseudoephedrine (HPED). J Label Compd Radiopharm 2000;43:603–12. 4. Rosenspire KC, Haka MS, Van Dort ME, Jewett DM, Gildersleeve DL, Schwaiger M, et al. Synthesis and preliminary evaluation of carbon‐11‐meta‐hydroxyephedrine: a false transmitter agent for heart neuronal imaging. J Nucl Med Off Publ Soc Nucl Med 1990;31:1328–34.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ Ca r di ol og y P-226 | Synthesis and biological evaluation of fluorescence‐ and gallium‐68‐labeled anti‐miR‐21 Eike Janssen; Jan Fiedler; Laura Langer; James Thackeray; Jens Bankstahl; Thomas Thum; Frank Bengel; Tobias Ross Hannover Medical School, Germany
Objectives MicroRNAs (miRNAs, miRs) are short, non‐coding RNAs that post‐transcriptionally regulate gene expression by binding to miRNA and thus play an important role in many biological processes (e.g., apoptosis, differentiation, and proliferation) and diseases (e.g., cancer, neurodegenerative, and cardiovascular). miRNA levels represent a promising new biomarker for the diagnosis of these diseases, even in a pre‐symptomatic state. Using radiolabeled anti‐miRNA oligonucleotides, which bind highly specifically and with high affinity to the complementary miRNAs, have the potential to assess miRNA levels in vivo. miR‐21 is involved in the development of cardiac fibrosis, which leads to myocardial dysfunction. [1,2] A radiolabeled anti‐miR‐21 oligonucleotide for PET would be valuable for the diagnosis of pathogenic changes in miR‐21 levels, even before disease associated symptoms occur. In this project, we aimed to develop radiolabeled oligonucleotides targeted to miR‐21 to evaluate potential as diagnostic tools in cardiac fibrosis. Methods Anti‐miR‐21 was functionalized with a hexyl‐disulfide moiety. The disulfide group was reduced with
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dithiothreitol and coupled with the fluorescent dye ATTO 647N and the complexing agent THP by maleimide thiol coupling to yield ATTO‐anti‐miR‐21 and THP‐anti‐miR‐ 21, respectively. Analytics were performed by HPLC and purification by Sephadex G‐25 in PD‐10 desalting columns. ATTO‐anti‐miR‐21 was incubated in mouse 3T3 fibroblasts for 24 h. qPCR was used to measure antisense effects. Transfection efficiency (LNA) was determined by FACS. THP‐anti‐miR‐21 was labeled with gallium‐68 in a first test run. 200 MBq of gallium‐68 eluate was added to the corresponding precursor at room temperature in water. The pH was adjusted to 6 with 1M ammonium acetate buffer, and the radiolabeling was monitored. Analytics were performed by radioHPLC. Results Two novel anti‐miR‐21 derivatives were successfully synthesized, ATTO‐anti‐miR‐21 and THP‐anti‐miR‐21. Based on the qPCR (miR‐21 knockdown) and FACS data (LNA transfection efficiency), we see that ATTO‐anti‐miR‐21 (100nM) is absorbed by mouse 3T3 fibroblasts and still has an inhibitory effect after 24 h, comparable with the inhibition effect of the unmodified anti‐miR‐21 (see figure). Initial radiolabeling demonstrated feasibility, though low radiochemical yield may reflect steric hindrance by the oligonucleotide. Further optimization of the reaction time, temperature, and the pH value is ongoing. Conclusions ATTO‐anti‐miR‐21 displays selective binding to miR‐21 in mouse 3T3 fibroblasts. The precursor THP‐anti‐miR‐ 21 can be labeled with gallium‐68. These studies form
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the foundation for non‐invasive imaging of miR‐21 levels in cardiovascular disease. In further studies, [Ga‐68]THP‐ anti‐miR‐21 will be evaluated in vivo by μPET imaging. ACKNOWLEDGEMENT The authors thank the International Isotope Society— Central European Division for support. R EF E RE N C E S 1. Gupta SK, Itagaki R, Zheng X et al. miR‐21 promotes fibrosis in an acute cardiac allograft transplantation model. Cardiovascular Research 2016; 110: 215‐226. 2. Thum T, Gross C, Fiedler J et al. MicroRNA‐21 contributes to myocardial disease by stimulating MAP kinase signalling in fibroblasts. Nature 2008; 456: 980‐984.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ Ca r di ol og y P-227 | Vulnerable atherosclerotic plaques imaging by VEGFR PET Zhen Yang; Feng Li; Dedipa Yelamanchili; Corina Rosales; Henry Pownall; Keith Youker; Dale Hamilton; Zheng Li Hannover Medical School, Germany
Objective Rupture of high‐risk or vulnerable plaques are responsible for majority of acute adverse cardiovascular events such as myocardial infarction or stroke. It is highly desirable to develop a non‐invasive imaging approach to detect atherosclerotic plaques that are prone to rupture for timely preventive treatment. Methods Vascular endothelial growth factors (VEGF) and its receptor is implicated in the development of plaque vulnerability and instability. Expression of VEGFRs in vulnerable plaques is highly increased comparing to more stable ones. In this study, a high affinity small molecule VEGFR‐targeting positron emission tomography (PET) radiotracer was developed for non‐invasive detection of vulnerable plaques in vivo. ApoE−/− mice developing aortic plaques were adopted as animal models for VEGFR PET scan, and human arterial specimen with appreciable atherosclerotic lesions was further investigated for specificity and sensitivity of the featured PET radiotracer in vulnerable plaques detection. Results We observed specific uptake of the VEGFR radiotracer in aortic plaques by in vivo and ex vivo PET imaging of ApoE−/− mice. Further histological study confirmed the
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vulnerable features of the aortic plaques along with high‐ level VEGFR expression in the mouse model. Moreover, autoradiographic and pathological study on human arterial specimen also showed a specific uptake of the PET radiotracer by vulnerable plaques developed in patient due to failing heart. Conclusions Our result demonstrated VEGFR is a useful biomarker for vulnerable plaques detection. Specific VEGFR PET provides a promising non‐invasive imaging modality for assessing plaque vulnerability in patient.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ C a r d i o l o g y P-228 | Detecting vulnerable atherosclerotic plaques by peptide
68
Ga‐labeled divalent cystine knot
Lei Jiang1; Zhen Cheng2 1
Shanghai Pulmonary Hospital, Tongji University School of Medicine,
China; 2 Stanford University, USA
Integrin αvβ3 has been considered as a promising biomarker for vulnerable atherosclerotic plaques, and it is highly expressed by those instability associated factors including macrophages, vessel endothelial cells, and smooth muscle cells. Our previous study successfully showed that 64Cu‐labeled divalent (containing two RGD motifs) cystine knot peptide, 64Cu‐NOTA‐3‐4A, had high binding affinity and specificity in targeting vulnerable carotid atherosclerotic plaques with increased αvβ3 levels. Therefore, considering that 68Ga has excellent nuclear physical properties for positron emission tomography (PET), the current study aimed to investigate the feasibility of using 68Ga‐NOTA‐3‐4A for PET study of vulnerable atherosclerotic plaques. The vulnerable carotid atherosclerotic plaques were induced and maintained in ApoE−/− mice through carotid artery ligation and high‐fat diet. Divalent knottin peptide 3‐4A was synthesized by solid‐phase peptide synthesis chemistry, and radiolabeled with 68Ga after conjugated with 1,4,7‐triazacyclononane‐1,4,7‐triacetic acid (NOTA). The stability of the probe was tested in phosphate buffered saline (PBS) buffer and mouse serum. Mice with atherosclerotic plaques (n = 4) were imaged by PET/CT at different time points after the tail vein injection of 68Ga‐ NOTA‐3‐4A. The receptor targeting specificity was confirmed by coinjection of the probe and non‐radioactive c (RGDyK) peptide. The carotid artery tissues were
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removed and immunofluorescence staining were performed to evaluate integrin αvβ3 expression. It was found that 68Ga‐NOTA‐3‐4A displayed high stability in PBS buffer and mouse serum. Small animal PET/CT images and quantification analysis indicated that 68Ga‐ NOTA‐3‐4A showed quick and high plaque uptake (6.67 ± 1.44%ID/g and 2.97 ± 0.46%ID/g at 1 and 2 h, respectively). The plaque‐to‐normal artery ratio was 15.88 and 9.90 at 1 and 2 h, respectively. Furthermore, the plaque uptake of 68Ga‐NOTA‐3‐4A was significantly inhibited by coinjection of c(RGDyK). Finally, immunostaining confirmed integrin expression by macrophages, vessel endothelial cells, and smooth muscle cells. In summary, 68Ga‐NOTA‐3‐4A has high potential to be a promising PET probe for imaging of vulnerable atherosclerotic plaques.
Poster Categ ory : R adiolabe led C o m p o u n d s ‐ N e u r o Sc i e n c e s P-229 | Improved synthesis of F18 MK6240, a PET tracer for neurofibrillary tangles Meixiang Yu; Chengfu Xu Houston Methodist Hospital Research Institute, USA
In an effort to make F18 MK6240 using the published procedures, we could not repeat the results. With low yield, especially in the deprotection procedure, we lost nearly 50% of the radiolabeled compound. After tests with different acids, different neutralizing bases, we finally got good yield after adding sodium ascorbate in the deprotection solution. Here, we report the brief procedures. After irradiation, O‐18 water containing [F‐18]
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fluoride is passed through a light QMA cartridge, which is eluted to the reaction vessel using 1.0 mL mixture of an aqueous kryptofix 222-K2CO3 solution (0.8 mL kryptofix 222 [8.75 mg/mL] in acetonitrile and 0.2 mL potassium carbonate [3.75 mg/mL] in O‐16 water). Anhydrous Kryptofix 222-K2CO3-[F‐18]fluoride is obtained after drying the solution with helium flow at 120°C. A solution of MK6240 precursor (2.5 ± 0.5 mg in anhydrous DMF [1 mL]) is added to the reaction vessel and the resulting mixture is kept at 90°C for 3 minutes, 110°C for 3 minutes, 120°C for 3 minutes and 140°C for 3 minutes, followed by de‐protection using a mixture of 0.5 mL 3M HCl (aq) and 0.5 mL 5% sodium ascorbate water solution at 120°C for 4 minutes. After cooling to 40°C, the crude F‐18 MK6240 mixture is neutralized with 1.0 mL of 1.5M NaOH (aq). The resulting mixture is diluted by 1 mL preparative mobile phase. The crude F‐ 18 MK6240 reaction mixture is loaded onto a semi ACE‐ C18, 10 × 250 mm, 5 μm HPLC column for purification (retention time is approximately 13 minutes) using the isocratic elution with a mobile phase of 35% acetonitrile and 65% 10 mM disodium hydrogen phospahte at a 6 mL/min flow rate in the first 2 minutes and then 8.5 mL/min. The HPLC fraction containing the product F‐18 MK6240 is collected and diluted with 80 mL of sterile water containing 1 mL 5% sodium ascorbate water solution. The diluted solution is then passed through a Light HLB cartridge. The retained F‐18 MK6240 is washed with 10 mL sterile water. F‐18 MK6240 product is eluted off the HLB cartridge using 1.5 mL of ethanol for injection, followed by 13.5 mL of saline 0.9% sodium chloride into a collection vial prefilled with 5.0 ± 1.0 mg sodium ascorbate. The final product solution is transferred into a 30 mL sterile vial through a 0.22 μm/ 33 mm Millex®‐GV sterilizing filter. In three validation tests, we received 316 ± 36 mCi (about 8.8% yield without
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decay correction, in about 90 minutes) with specific radioactivity of 11,638 ± 1,360 mCi/μmol, all other quality control tests pass the criteria. Conclusion: an efficient F‐18 MK6240 radiolabeling procedure was developed.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ N euro S ci ences P-230 | Radiosynthesis and in vitro characterization of an iodine‐125 labeled radiotracer for α‐synuclein Zhude Tu1; Xuyi Yue2; Jiwei Gu2; Zonghua Luo2; Chi‐chang Weng3; Zsofia Lengyel4; Dhruva Dhavale2; Paul Kotzbauer2; Robert Mach5 1
Department of Radiology, Washington University School of Medicine in
Saint Louis, USA; 2 Washington University in St. Louis School of Medicine, USA; 3 Department of Radiology, University of Pennsylvania, USA; 4
University of Pennsylvania School of Medicine, USA; 5 University of
Pennsylvania, USA
Objectives The aggregation of misfolded α‐synuclein protein is a pathological hallmark of Parkinson's disease (PD) and other synucleinopathies, such as Dementia with Lewy Bodies (DLB) and Multiple System Atrophy (MSA). A clinically suitable positron emission tomography (PET) radioligand for quantitative assessment of the α‐synuclein aggregations in the brain would have a tremendous value in early diagnosis of PD, monitoring the disease progression, and assessment of the efficacy of disease‐modifying therapies in early disease stage. Lack of suitable α‐ synuclein radioligands to screen α‐synuclein binding affinities of new ligands hampers the identification of novel PET radioligand for imaging the α‐synuclein aggregation in vivo. Here, we reported our recent efforts on the development of an iodine‐125 labeled radiotracer and in vitro characterization of its binding properties with α‐ synuclein fibrils. Methods Commercially available propargyl alcohol was reacted with tributyltin chloride, followed by iodination to afford
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(E)‐3‐iodoprop‐2‐en‐1‐ol, which was brominated with carbon tetrabromide to afford (E)‐3‐bromo‐1‐iodoprop‐1‐ ene. The following O‐alkylation on the quinolinyl‐ containing phenol intermediate generated the reference standard compound TZ6184. The radiosynthesis of [125I] TZ6184 was accomplished by tin/iodine exchange reaction. The radioactive [125I]NaI was added into corresponding tin precursor in a freshly made mixture of H2O2 (30%)/acetic acid (1/2, v/v), the reaction was stirred 15 min at room temperature, and then the reaction mixture was purified on a semi‐preparative reversed‐phase HPLC column combined with solid‐phase (C‐18 cartridge) extraction. The [125I]TZ6184 was eluted out using 1.0 mL of absolute ethanol. The in vitro characterizations of [125I]TZ6184 binding toward α‐synuclein was performed using direct radioactive competitive binding screening procedure. Briefly, recombinant a‐synuclein fibrils (100nM) was incubated with radioligand ([125I] TZ6184 at different concentration ranging from 0.01nM to 2.0nM at 37°C for 60 min. After the bound and free radioligand were separated by vacuum filtration through 1.0 mm glass fiber filters in 96‐well filter plates (Millipore), followed by three 200 mL washes with ice‐ cold assay buffer, filters containing the bound ligand were mixed with 150 mL of Optiphase Supermix scintillation cocktail (PerkinElmer) and counted immediately. All data points were performed in triplicate. The dissociation constant (Kd) and the maximal number of binding sites (Bmax) values were determined by fitting the data to the equation. The Kd and Bmax were calculated Results The reference compound TZ6184 was successfully synthesized and the radiolabeled [125I]TZ6184 was achieved with a good radiochemical yield (50‐60%) and radiochemical purity > 99%. Using the direct radioligand competitive binding assay, it was found that [125I]TZ6184 has very high potency toward recombinant α‐synuclein fibrils with a Kd value of 0.39nM, the Bmax value of 148 fmol/nmol. Conclusions A new high potent iodine‐125 labeled radiotracer, [125I] TZ6184 was identified. In vitro characterization using α‐ synuclein fibrils was carried out and [125I]TZ6184 is very potent for α‐synuclein fibrils with a high Bmax value.
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Further characterization of [125I]TZ6184 will determine [125I]TZ6184 is a suitable a radioligand for screening other new analogues. Meanwhile, further characterization of carbon‐11 labeled version of compound TZ6184 will determine its feasibility for imaging α‐synuclein aggregation in the brain in vivo. Research Support: Michal J Fox Foundation for Parkinson's Research‐Developing an Alpha‐Synuclein Imaging Agent.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ N euro S ci ences P-232 | Dosimetry and toxicology of [18F] MC225 for measuring P‐glycoprotein function at the blood‐brain barrier in humans Jun Toyohara1; Muneyuki Sakata1; Tetsuro Tago1; NIcola Colabufo2; Gert Luurtsema3 1
Tokyo Metropolitan Institute of Gerontology, Japan; 2 Università degli
Studi di Bari, Italy; 3 University Medical Center Groningen, Netherlands
Objectives Fluorine‐18 labelled 5‐(1‐(2‐fluoroethoxy))‐[3‐(6,7‐ dimethoxy‐3,4‐dihydro‐1H‐isoquinolin‐2‐yl)‐propyl]‐ 5,6,7,8‐tetra‐hydronaphthalen ([18F]MC225) is a selective substrate for P‐glycoprotein (P‐gp) with a good metabolic stability and showed higher baseline uptake than that of other P‐gp substrates, such as (R)‐[11C]Verapamil.[1] It is required to perform toxicity and dosimetry studies because the planned phase 1 studies with [18F]MC225. Herein, we report the preclinical biodistribution, dosimetry, and toxicology studies of [18F]MC225.
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Methods In vivo biodistribution and dosimetry studies of [18F] MC225 were carried out in normal mice to determine the route of excretion and to estimate human dosimetry. Rodent biodistribution studies were conducted with all major organs at 5‐time points (4 male mice for each time points). Human dosimetry was estimated using OLINDA software. The acute toxicity of MC225 at a dose of 2.5 mg/ kg body weight, which is more than 10,000‐fold postulated maximum clinical dose of [18F]MC225, was evaluated. Acute toxicity of [18F]MC225 injection of a 200‐ fold dose to administer a postulated dose of 185 MBq of [18F]MC225 was also evaluated after the decay‐out of 18 F. The mutagenicity of MC225 was studied by a reverse mutation test in Salmonella typhimurium and Escherichia coli (Ames test). Results Biodistribution study demonstrated both hepatobiliary and renal excretion of radioactivity (Figure 1). The absorbed dose (μGy/MBq) calculated with urination at 360 min after injection was highest in pancreas (64.0), small intestine (36.2), urinary bladder wall (32.8), and upper large intestine wall (30.7). The absorbed dose calculated without urination was highest in pancreas (63.9), urinary bladder wall (59.6), small intestine (36.3), and upper large intestine wall (30.6). The estimated effective dose of urinated and non‐urinated were calculated as 18.2 μSv/MBq and 19.6 μSv/MBq, respectively. Acute toxicity in rats was evaluated after a single intraperitoneal injection of MC225 at a dose of 2.5 mg/kg and a single intravenous injection of [18F]MC225 preparations at a dose range of 1.68–13.15 μg/kg. No mortality was found in the rats during the 14‐day observation period. All rat groups showed normal gains in body weight compared with the control animals, and no clinical signs of toxicity were observed over a 15‐day period. No abnormalities
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were found with postmortem macroscopic examination. When a bacterial reverse mutation test was conducted using the Salmonella thyphimurium and Escherichia coli mutation test, no mutagenic activity was observed for MC225. Conclusions A single i.v. injection of 185 MBq of [18F]MC225 leads to an estimated effective dose of 3.4 (urinated) and 3.6 (non‐ urinated) mSv and an estimated dose to the highest organ of 11.8 (urinated and non‐urinated) mGy. The potential risk associated with [18F]MC225 PET imaging is well within acceptable limits. Preclinical toxicological studies indicate that [18F]MC225 shows the acceptable pharmacological safety at the dose required for adequate PET imaging. Taken in account the high molar activity (>1000 GBq/μmol) and low total chemical contents (98% radiochemical purity and 70–112 GBq/μmol molar activity. In vitro autoradiography showed that the distribution pattern of [11C]1 radioactivity was heterogeneous with high expression in the cerebral cortex, striatum, hippocampus, and cerebellum. This distribution pattern was consistent with the distribution of mGluR2 in the rat brain. The radioactivity was significantly reduced by self‐ or MNI‐137 (a mGluR2 NAM) blocking. In the mouse brain, the initial uptake of [11C]1 was 1.1%ID/g at 1 min. PET study showed that the uptake of radioactivity peaked at 2 min with a SUV of 0.72 in the cerebral cortex and rapidly decreased afterwards. Self‐ blocking with 1 produced a fairly uniform distribution of radioactivity in all brain regions. The PET results suggest that a certain level of in vivo specific binding of [11C]1 could be found in the rat brain. The whole brain uptake increased 74% in Pgp/BCRP‐KO mice, compared to that in wild‐type mice (calculated from the area under curve). Metabolite analysis showed most radioactivity in
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the brain represented the unchanged [11C]1. On the other hand, PET with [11C]VU6001192 showed a very low brain uptake (SUV < 0.3). Conclusion In this study, we have synthesized [11C]1 as a new PET tracer with good radiochemical yield, high radiochemical purity, and high molar activity. While [11C]1 has limited potential as a PET tracer for the imaging of brain mGluR2, it can be used to develop new radiotracers with improved in vitro profiles and in vivo behaviors. RE FER EN CE 1. Bollinger K. A., Felts A. S., Brassard C. J., et al. ACS Med. Chem. Lett. 2017, 8, 919–924.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ N e u ro Sc i e n c e s P-240 | Synthesis and evaluation of tropane‐based, radiometal‐labeled CNS tracers for the visualization of the dopaminergic transporter system Sascha Häseli1; Frank Roesch2 1
Institute for Nuclear Chemistry, Johannes Gutenberg‐Universität Mainz,
Germany; 2 Johannes Gutenberg‐Universität Mainz, Germany
Aim For the diagnosis of neurological questions using positron emission tomography (PET), high demands are placed on the radiopharmaceuticals used with regard to their biological properties. For this reason, most central nervous system (CNS) tracers (except the 99mTc‐ and 123I‐DAT tracers for SPECT) are currently labeled with the non‐ metallic positron emitters carbon‐11 and fluorine‐18. Due to better availability and simpler radiochemistry, however, it would be desirable to be able to use analogues labeled with generator‐based gallium‐68 for CNS diagnostics. Thus, in this work, we concentrated on the synthesis and evaluation of a 68Ga‐labeled tropane based tracer for visualization of the dopaminergic transporter (DAT) system. Methods The bifunctional chelators of DOTA, NOTA, MAMA′, and TACN‐TM coupled with the DAT tracer 2β‐ carboxymethoxy‐3β‐(4‐methylphenyl)‐tropane were synthesized. The coupling was realized via N‐substitution while the spacer was varied in length and composition, that is an alkyne moiety following the DAT‐tracer [18F]
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PR04.MZ.[1] Labeling was performed using 100 MBq gallium‐68 (0.2M NaOAc‐buffer, pH = 4.5). Labeling kinetics were carried out over 15 min, in vitro stability studies in PBS‐buffer and human serum over 2 h. Tracer lipophilicities were measured via shake‐flask method as distribution coefficients (log D values) between n‐octanol and water. Results So far, the organic synthesis of three DOTA conjugates has been completed, while the remaining ones are currently in progress. All DOTA based tracers labeled gallium‐68 in quantitative yields at 95 °C in under 10 min even at high activities and low tracer concentrations up to 10 nmol. Furthermore, they showed excellent in vitro stability in PBS as well as in human serum over two hours of 100%. Lipophilicities were measured for the spacer types C2, C3, and alkyne to log D = −2.06 (±0.11), −2.01 (±0.09), and −2.21 (±0.17), respectively. Conclusions An efficient synthesis route was developed to obtain a wide variety of chelators coupled to a high affinity DAT ligand analogous to [18F]PR04.MZ. First radiolabeling as well as in vitro studies showed promising results. Currently, we are evaluating the tracers in a blood brain barrier model and are testing their affinity to the DAT. Especially, the highly lipophilic chelator TACN‐TM offers great potential as a CNS tracer.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ N euro S ci ences P-241 | Characterization of the rotenone mouse model of Parkinson's disease using radioligands for the adenosine A2A receptor ([18F]FESCH) and the nicotinic α4β2 receptor ((−)‐[18F]Flubatine) Magali Toussaint1; Mathias Kranz1; Susann Schröder2; Thu Hang Lai1; Winnie Deuther‐Conrad1; Sladjana Dukic‐Stefanovic1; Qi Shang3,4; Marianne Patt5; Heinz Reichmann6; Richard Funk7; Osama Sabri5; Francisco Pan‐Montojo3; Peter Brust1 1
Department of Neuroradiopharmaceuticals, Helmholtz‐Zentrum
Dresden‐Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany; 2 Department of Research and Development, ROTOP Pharmaka GmbH, Dresden, Germany; 3 Ludwig‐Maximilians‐Universität Munich, University Hospital GroßhadernNeurological Clinic & Polyclinic, Department of Neurology, Munich, Germany; 4 Clinic of Neurology, Technische Universität Dresden, University Hospital Carl Gustav Carus,
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Dresden, Germany; 5 Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany; 6 Department of Neurology, Technische Universität Dresden, University Hospital Carl Gustav Carus, Dresden, Germany; 7 Institute of Anatomy, Technische Universität Dresden, University Hospital Carl Gustav Carus, Dresden, Germany
Objectives Rotenone‐treated mice are regarded as a model for Parkinson's disease (PD). Increased availability of the adenosine A2A receptor (A2AR) and decreased availability of the α4β2 nicotinic acetylcholine receptor (nAChR) have been found in the striatum and thalamus, respectively, of patients with PD.1,2 Therefore, we evaluated the potential of [18F]FESCH (for A2AR) and (−)‐[18F]Flubatine (for α4β2nAChR) to characterize similar receptor changes in the mouse model of PD with small animal PET/MR imaging. Methods Two groups of 18‐months‐old male C57BL/6JRj mice (28‐35 g) (Janvier labs, France) were investigated: a control group (n = 5) treated with a vehicle solution (2% carboxymethyl cellulose, 1.25% chloroform) and a PD group (n = 7) treated with rotenone (Sigma‐Aldrich, Germany) during 4 months (5 days/week, 5 mg/kg p.o.). [18F]FESCH (5.0 ± 1.8 MBq; Am: 116 ± 19 GBq/μmol, EOS) or (−)‐[18F]Flubatine (6.5 ± 2.4 MBq; Am: 1080 ± 2156 GBq/μmol, EOS) were injected intravenously followed by 60 min dynamic PET scans (Mediso nanoScan®, PET/MRI 1T, Hungary). Time‐activity curves from the striatum, cerebellum, and thalamus were analyzed (PMOD v3.9, PMOD Technologies LLC, Switzerland). The cerebellum was used as a reference tissue. Results PET scans revealed high uptake of (−)‐[18F]Flubatine in thalamus (SUV ~3.5 at 40 min p.i.) and considerably lower uptake in cerebellum (SUV ~1.2 at 40 min p.i.). The SUV ratio (SUVR) thalamus/cerebellum, indicating specific radiotracer binding, is significantly decreased in the rotenone‐treated group compared to the control (Figure 1A). Also for [18F]FESCH much higher uptake was observed in striatum (SUV ~0.9 at 5 min p.i.) compared to cerebellum (SUV ~0.2 at 5 min p.i.). Although not significant for this rather small and highly variable data set, the SUVR striatum/cerebellum is increased in the rotenone‐treated group compared to the control suggesting a higher specific binding in striatum (Figure 1B). These findings are in accordance with a recent publication.3 Conclusion We have established a concordance between clinical imaging findings in PD and small animal PET/MR in
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rotenone‐treated mice. Thus, we assume the rotenone mouse model to be suitable for further investigation of molecular aspects of PD in particular related to A2AR and α4β2nAChR. ACKNOWLEDGMENTS The European Regional Development Fund and Sächsische Aufbaubank are acknowledged for financial support (Project No. 100226753).
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ N e u ro Sc i e n c e s
R EF E RE N C E S
Ahmed Haider1; Hazem Ahmed1; Jasmine Varisco1; Maja Stankovic1; Rahel Wallimann1; Stefan Gruber1; Irina Iten1; Jose Miguel4; Claudia Keller1; Roger Schibli1; Dirk Schepmann2; Linjing Mu1; Bernhard Wünsch2; Simon Ametamey3
1. Vuorimaa et al. Contrast Media Mol Imaging 2017; 6975841. 2. Meyer et al., Arch Gen Psych 2009, 66: 866‐877. 3. Khanapur et al., J Nucl Med 2017; 58: 466–472.
P-242 | Evaluation of fluorinated benzazepine and benzo[7]annulen‐7‐amine analogues for development as imaging agents for the GluN2B subunits of the N‐methyl‐D‐aspartate receptor
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ETH Zurich, Switzerland; 2 Department of Pharmaceutical and
Medicinal Chemistry, University of Münster, Germany; 3 Radiopharmacy, ETH Zurich, Switzerland; 4 Esteve, Spain
Objectives Positron emission tomography (PET) imaging is an imaging modality that can orchestrate the development process of GluN2B antagonists in preclinical and clinical stages through target engagement and receptor occupancy studies. However, currently no clinically validated GluN2B PET tracer exists. We recently succeeded in developing a carbon‐11 labeled GluN2B PET radioligand, codenamed [11C]‐Me‐NB1,1 that is currently being translated into clinical practice. As part of our efforts to develop a fluorine‐18 labeled GluN2B PET ligand, we designed, synthesized, and tested several benzazepine and benzo[7]annulen‐7‐amine analogues of Me‐NB1. Methods Twelve analogues were synthesized in a multi‐step reaction sequence and tested in an in vitro competitive binding assay for affinity determination for the GluN2B subunits as well as the closely related off‐target sigma receptors. The most promising ligands exhibiting high nanomolar affinity and selectivity were selected for radiolabeling. Further evaluation was carried out by performing in vitro autoradiography on rodent brain tissues. Based on the autoradiograms, a derivative designated [18F]PF‐NB1 was selected for further in vivo PET imaging studies in rodents. Results Compared to Me‐NB1, PF‐NB1 showed a two‐fold higher nanomolar binding affinity towards GluN2B receptors and a sixty‐fold selectivity over sigma‐1 receptors. [18F] PF‐NB1 was synthesized from an aryl pinacolboronic ester precursor in two steps via copper‐mediated radiofluorination in good radiochemical yields of 14‐17% and high molar activities ranging from 148‐258 GBq/ μmol. In in vitro autoradiographic studies, [18F]PF‐NB1 showed a heterogeneous binding pattern on rat and
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mouse brain sections with high accumulation in GluN2B‐rich areas including the cortex, striatum, thalamus, and hippocampus and low accumulation in GluN2B‐poor regions such as the cerebellum. Radioactivity accumulation was specifically blocked with 1 μM solution of GluN2B specific ligand, CP‐101,606 but not with sigma‐1 and sigma‐2 receptor specific ligands fluspidine and PB28 (Figure 1). PET imaging studies in Wistar rats revealed high in vivo specific binding in the brain and an appropriate pharmacokinetic profile. Off‐target binding to sigma‐1 receptors was also excluded by in vivo PET imaging with wild‐type and sigma‐1 receptor knock‐out mice. Conclusion [18F]PF‐NB1 is a promising radioligand for the in vivo imaging of GluN2B‐containing NMDA receptors. ACKNOWLEDGMENTS This project was supported by the Swiss National Science Foundation Grant Nr. 310030E‐160403/1. RE FER EN CE 1. Kramer SD, Betzel T, Mu L, et al. Evaluation of (11)C‐Me‐NB1 as a potential PET radioligand for measuring GluN2B‐containing NMDA receptors, drug occupancy, and receptor cross talk. J Nucl Med. 2018;59(4):698‐703.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ N e u ro Sc i e n c e s P-243 | Progress towards the first adenosine A1R full agonist PET radioligand Min Guo1; Zhan‐Guo Gao2; Joseph Ramsey3; Tyler Stodden3; Cameron Javdan4; Luana Carvalho3; Kenneth Jacobson2; Sung Won Kim1; Nora Volkow5 1
National Institutes of Health/National Institute on Alcohol Abuse and
Alcoholism, USA; 2 Laboratory of Bioorganic Chemistry, National Institute
Figure 1 Representative in vitro autoradiograms of [18F]PF‐NB1 obtained from mouse coronal brain sections. 1 μM concentrations of the blockers were used, GluN2B antagonist, CP‐101,606 was used tp establish specificity of [18F] PF‐NB1 binding to GluN2B subunits, whereas fluspidine and PB28, inhibitors of sigma‐1 and sigma‐2 receptors, respectively were used to exclude off‐target binding of [18F]PF‐NB1 to sigma receptors.
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of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, USA; 3 Laboratory of Neuroimaging, National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, USA; 4 University of Maryland College Park, USA; 5 Laboratory of Neuroimaging, National Institute of Alcohol Abuse and Alcoholism, National Institute on Drug Abuse, National Institutes of Health, USA
Objective Central adenosine A1 receptors play a vital role in the sleep‐wake cycle, pain, cognition, substance use disorders, and neurodegenerative diseases. Thus, radiotracers targeting A1R have been intensively studied, though mostly these have focused on antagonist radioligands. Although these radiotracers have been successful at mapping CNS A1R, they have failed at measuring the interactions between endogenous adenosine and A1R.1,2 We reasoned that, an agonist A1R radiotracer would be more sensitive to endogenous adenosine as it competes at the same binding site. Recently, we reported a first partial A1R agonist radioligand [11C]MMPD, with sub‐ nanomolar affinity, high specificity, and high selectivity.3 Moving forward, we present our progress towards a non‐ nucleoside full agonist radioligand targeting A1R in the brain. Methods Based on 3,5‐dicyanopyridine and 5‐cyanopyrimidine templates that showed superior blood‐brain barrier (BBB) permeability with functional agonism in our previous report,3 parallel synthesis was performed to provide two sets of structurally diverse derivatives. A library of 20 compounds was prepared. Systematic in vitro structure‐activity relationship (SAR) studies (Figure 1) were carried out for hA1, hA2A, and hA3R subtypes. BDPD, an potent A1R full agonist, was selected for labeling and radiolabeled with its nor‐precursor and [11C]MeI. Preclinical evaluations of [11C]BDPD binding in brain were performed on Wistar rats (male, 250‐350 g) using PET. Whole brain uptake ex vivo was measured in efflux pump KO mice at 15 min post iv injection of [11C]BDPD. Results We observed that 3,5‐dicyanopyridine was an important pharmacophore overall (Figure 1, highlighted in blue). p‐Acetamido substituent at the R1 position favored A2AR selectivity, which was very sensitive to subtle changes. However, simple substituents (e.g. –OH, –OMe, –F, – OCH2CH2F), particularly at the R2 position, rendered better A1R selectivity and functional efficacy. Binding affinity could be tuned by small heteroaromatics at the R3 position. Among the 20 analogs, BDPD showed excellent subtype selectivity (Ki = 1.6 ± 0.4 at hA1, >1000nM
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at hA2A and hA3R) and full hA1R agonism (104 ± 5.9%, based on cAMP accumulation assay, with NECA set to 100%). [11C]BDPD was synthesized with moderate radiochemical yield (~20%), high radiochemical purity (>99%) and good specific activity (67 ± 41 GBq/μmol, n = 3). Preliminary PET imaging showed lack of BBB permeability (SUV, ~0.2 g/mL) in rat studies (Figure 1, n = 2). Moderately increased brain uptake was observed in efflux pump KO mice, compared with control mice (Table 1). Conclusions Based on SAR probing, a second‐generation adenosine full agonist radioligand was synthesized and evaluated in rodent PET studies. Although [11C]BDPD as an A1R full agonist has high in vitro A1R binding affinity and selectivity, it failed to cross BBB. Ex vivo mice studies showed that [11C]BDPD might be a weak substrate for common efflux pump proteins (Table 1). However, brain uptake in efflux pump KO mice was still very low, presumably due to the high molecular weight and large polar surface area of BDPD. This in vivo information can be used to guide further structural modifications. C‐11 radiolabeling with our next A1R full agonist candidate is ongoing, and we will disclose the results in due course. ACKNOWLEDGEMENTS This work was supported by intramural research program of NIAAA/NIH (Y1AA‐3009, N.D.V.) and NIDDK/NIH (ZIADK031117, K.A.J.). RE FER EN CES 1. Paul, S., et al., Small‐animal PET study of adenosine A1 receptors in rat brain: blocking receptors and raising extracellular adenosine. Journal of Nuclear Medicine, 2011.52(8): p. 1293‐1300. 2. Paul, S., et al., Use of 11C‐MPDX and PET to study adenosine A1 receptor occupancy by nonradioactive agonists and antagonists. Journal of Nuclear Medicine, 2014.55(2): p. 315‐320. 3. Guo, M., et al., Preclinical evaluation of the first adenosine A1 receptor partial agonist radioligand for positron emission tomography imaging. Journal of Medicinal Chemistry, 2018.61(22): p. 9966‐9975.
TABLE 1 Biodistribution data of whole brain from KO and control mice 15 min post iv injection of [11C]BDPD. MDR1a/ 1a‐KO
BCPR‐KO
MRP1‐KO
Control
SUV (n) 0.29 (n = 2) 0.08 (n = 2) 0.22 (n = 3) 0.12 (n = 1)
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Poster Cate gory: Radiola bele d C o m p o u n d s ‐ N euro S ci ences
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Gita Rahardjo; Nageshwar Yepuri; Rachael Shepherd; Rhys Murphy; Tien Pham; Vu Nguyen; Paul Callaghan; Peter Holden; Marie‐Claude Gregoire; Tamim Darwish
P-244 | Fluorine‐18 radiolabelling and in vitro/in vivo metabolism of [18F]D4‐PBR111
Australian Nuclear Science and Technology Organisation, Australia
Benjamin Fraser; Mitra Safavi‐Naeini; Andrew Wotherspoon; Andrew Arthur; An Nguyen; Arvind Parmar; Hasar Hamze; Charmaine Day; David Zahra; Lidia Matesic; Emma Davis;
Objectives The 18 kDa Translocator Protein (TSPO) is a receptor protein located in the outer mitochondrial membrane.1,2
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TSPO is a bio‐marker for inflammation associated with numerous diseases including cancer, multiple sclerosis, Parkinson's and Alzheimer's diseases, stroke, 3,4 ConseHuntington's disease, and HIV encephalitis. quently, there is significant interest in radiolabelled TSPO ligands as new radiotracers. This includes [18F]PBR111 which shows potential for imaging neuroinflammation5,6 but suffers from significant de‐fluorination in vivo (rats). This leads to non‐specific bone uptake and low signal‐to‐ noise ratios in vivo, leading to lower quality PET images. To address these problems, a deuterated 2nd generation radiotracer has been synthesised and its metabolic stability compared to regular [18F]PBR111. Methods The synthesis of [18F]D4‐PBR111 radiolabelling precursor was achieved following an adaptation of our previously published method.5 The radio‐synthesis of [18F]PBR111 and [18F]D4‐PBR111 was performed on a Synthra synthesis module by nucleophilic substitution of PBR111 or D4‐ PBR111 tosylate precursor with [18F]fluoride based on adaptations of conditions previously described.5 In vitro metabolism was evaluated by incubating [18F]PBR111 or [18F]D4‐PBR111 with either rat or human liver microsomes, NADPH generating solution and 0.1M potassium phosphate buffer pH 7.4 (PBS) at 37°C. Supernatant was collected at various time points over a 60 min period. The supernatant was then analysed via radio‐HPLC to determine the metabolite components. A control sample was used for each assay containing all the components of the assay apart from the NADPH generating solution to rule out any breakdown of the radiotracer not caused by the microsomal process. In vivo PET and metabolite studies consisted of male Sprague Dawley Rats (n = 16) being injected with either 100 MBq [18F]PBR111 or [18F] D4‐PBR111 and a PET acquisition was performed for a
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60 min scan. During this process blood samples were taken from the rats at various time points up to 60 min via the femoral artery. Plasma was separated from whole blood and the percentage of the metabolite components and the in‐tact tracer was analysed by radio‐HPLC and Solid Phase Extraction (SPE) as previously described.5 Results In vitro assay results showed the presence of 7 visible [18F] radio‐metabolite peaks and were given a numerical value based on their polarity on the HPLC chromatogram. The results showed that rat microsomes metabolised both [18F]PBR111 and [18F]D4‐PBR111 much faster than the human microsomes. In vivo PET imaging in rats showed a 42% reduction of the median [18F]D4‐PBR111 (Figure 1, A) uptake in bone (vertebrae) compared to non‐deuterated [18F] PBR111 (Figure 1B). This data supports the hypothesis that the introduction of deuterium has significantly reduced the de‐ fluorination of the PBR111 radiotracer. Conclusions A deuterated radiotracer [18F]D4‐PBR111 was developed and evaluated in vivo in rats, demonstrating that it is more resistant to metabolic breakdown compared to non‐deuterated [18F]PBR111. Careful choice of the site of deuteration resulted in a decreased rate of de‐ fluorination, and a notable increase in the median uptake of the radiotracer in regions with high TSPO expression. Rat and human liver microsomal assays were an effective screening tool for predicting the potential metabolic differences between the deuterated and non‐deuterated analogues. Our results provide further evidence of the benefit that deuterium can have, not only, in stabilisation but also in altering the metabolic profile of a radiotracer. Further studies are now underway to evaluate [18F]D4‐ PBR111 vs [18F]PBR111 in animal disease models.
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ACKNOWLEDGMENTS The authors gratefully acknowledge the support of the Australian Institute of Nuclear Scientists and Engineers (AINSE) for the provision of post‐graduate student scholarships. The authors gratefully acknowledge the support of the Australian National Imaging Facility (NIF). R EF E RE N C E S 1. Braestrup et al. Proceedings of the National Academy of Sciences of the United States of America. 1977;74(9):3805‐9. 2. Snyder SH et al. Faseb J. 1987;1(4):282‐8. 3. Li et al. Pharmacol Res. 2015;99:404‐9. 4. Papadopoulos et al. Exp Neurol. 2009;219(1):53‐7. 5. Fookes et al. J Med Chem. 2008;51(13):3700‐12. 6. Dedeurwaerdere et al. EJNMMI Research. 2012;2:60.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ N euro S ci ences P-245 | A novel imaging probe with selectivity for tau‐oligomeric protein aggregates: In vitro evaluation and radiolabelling with fluorine‐18 Stephen Thompson1; Yanyan Zhao1; Ole Tietz2; Franklin Aigbirhio1 1
University of Cambridge, UK; 2 Molecular Imaging Chemistry
Laboratory, Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, UK
Objectives Soluble, oligomeric aggregates of misfolded proteins like amyloid beta (Aβ) and tau are neurotoxic and cause damage to neurons in the early stages of neurodegenerative diseases before the development of cognitive symptoms.1 At present, we lack selective molecular tools to image and interrogate the formation of soluble oligomers of Aβ and tau in vivo. Such molecular tools, and their translation into PET ligands would facilitate our understanding of the origin and progression of neurodegenerative diseases. Towards this goal, we have developed pTP‐ TFE, a fluorescent oligothiohene compound containing several fluorine atoms, which would enable imaging applications using 19F MRI and 18F PET. Herein, we describe the in vitro behaviour of pTP‐TFE and progress towards radiolabelling pTP‐TFE with fluorine‐18 for in vivo PET studies. Methods To investigate the ability of pTP‐TFE to detect small, soluble aggregates, pTP‐TFE, its analogue pFTAA2 and thioflavin‐T were each incubated with Aβ monomer and
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tau monomer at 37°C at pH 7.4. The change in fluorescence was measured over the course the aggregation reaction, and the species present at each timepoint were confirmed by transmission electron microscopy. (TEM) The affinity (Kd) of pTP‐TFE the different sized aggregates of Aβ and tau were also measured. For radiolabelling with fluorine‐18, [18F]fluoride was azeotropically dried to afford [18F]KF•K222•K2CO3 complex using standard methods. Addition of [18F] KF•K222•K2CO3 to difluoroiodomethane in MeCN gave [18F]fluoroform, that was distilled from the reaction mixture. [18F]Fluoroform was trapped in DMF at −60°C, before KOtBu and 2‐bromothiophenecarboxaldehyde were added at room temperature. HPLC of the reaction mixture spiked with authentic standard was used to confirm formation of the desired 18F‐labelled product. Results ThT fluorescence increases at the late stages of the aggregation of Aβ and tau, as β‐sheet fibrillar aggregates of the proteins form. In contrast, the fluorescence of pFTAA increases early in the aggregation reaction, when TEM confirms the presence of oligomers of the proteins at these timepoints. pTP‐TFE behaves similarly to pFTAA; however, the increase in fluorescence occurs earlier during the aggregation reactions of Aβ and tau, suggesting that pTP‐TFE binds even smaller oligomeric aggregates than pFTAA. Measurements of the binding affinity (Kd) of pTP‐TFE to aggregates of Aβ and tau of increasing size showed that pTP‐TFE had a Kd = 60 nM for the tau‐ oligomer rich fraction, while smaller and larger tau aggregates and all fractions of Aβ have a Kd ≈ 1 μM. This suggests that pTP‐TFE is a probe selective for binding to tau oligomers and is a promising candidate for radiolabelling with fluorine‐18 for PET imaging of oligomeric tau in vivo. Towards this end, [18F]‐1‐(5‐bromothiophen‐2‐ yl)‐2,2,2‐trifluoroethan‐1‐ol was identified as the key intermediate towards the synthesis of [18F]pTP‐TFE. Vugts et al,3 described the synthesis of aryl [18F] trifluoroethanols by reaction of an aldehyde with [18F] fluoroform‐derived [18F]CF3−. Using this method, [18F] fluoroform was isolated in 25 % (n = 6) n.d.c. radiochemical yield (RCY), and [18F]‐1‐(5‐bromothiophen‐2‐yl)‐ 2,2,2‐trifluoroethan‐1‐ol was synthesised in 66% crude RCY from [18F]fluoroform and the corresponding aldehyde. Conditions for the Suzuki coupling of this fragment with the appropriate boronic ester precursor to give [18F] pTP‐TFE are ongoing. Conclusions We have developed a novel pTP‐TFE, an oligothiophene derivative that binds to tau oligomers with high affinity and selectivity. To our knowledge, we believe this to be the first probe with this selectivity. Radiolabelling p‐TP‐ TFE with fluorine‐18 is ongoing, and [18F]‐1‐(5‐
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bromothiophen‐2‐yl)‐2,2,2‐trifluoroethan‐1‐ol has been successfully prepared in 64% crude RCY. ACKNOWLEDGEMENTS We wish to thank Prof. Maria Spillantini and Prof. David Klenerman and the NIHR, Cambridge Biomedical Research Unit and EPSRC for funding. R EF E RE N C E S 1. Cárdenas‐Aguayo M. del C. et al., ACS Chem. Neurosci., 2014, 5, 1178–1191. 2. Åslund A. et al., ACS Chem. Biol., 2009, 4, 673–684. 3. van der Born D. et al., Chem. Commun., 2013, 49, 4018.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ N euro S ci ences P-246 | SPECT imaging of the glymphatic pathway with rat brain
111
In‐labeled ovalbumin in the
Vladimir Shalgunov1; Tuomas Lilius2; Björn Sigurðsson2; Simone Larsen Bærentzen2; Natalie Linea Hauglund2; Matthias Herth3; Mikael Palner4; Maiken Nedergaard2 1
Department of Drug Design and Pharmacology, University of
Copenhagen, Denmark; 2 left for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 3
University of Copenhagen, Sweden; 4 Neurobiology Research Unit,
Copenhagen University Hospital, Denmark
Objectives The glymphatic pathway is a fluid transport system in the central nervous system (CNS). It facilitates the influx of cerebrospinal fluid (CSF) to the CNS interstitium to promote the clearance of extracellular solutes. Subarachnoid CSF flows into the brain along perivascular spaces of penetrating arteries and enters the interstitium driven by arterial pulsatility and facilitated by astrocytic aquaporin 4 (AQP4) channels. The fluid disperses in the brain interstitium and leaves the brain via perivenous spaces, cranial and spinal nerves as well as meningeal lymphatic vessels.1 The glymphatic system has been visualized in mice by two‐photon fluorescence imaging using fluorescently labeled ovalbumin.2 However, this method demands invasive surgery and the imaging area is restricted only to the brain parenchyma and the perivascular spaces. We aimed to image the glymphatic pathway in the whole brain by means of single photon emission computed tomography (SPECT) using radiolabeled ovalbumin as a CSF tracer. Methods Ovalbumin was conjugated with the bifunctional chelator p‐SCN‐Bn‐DOTA (2‐S‐(4‐isothiocyanatobenzyl)‐1,4,7,10‐ tetraazacyclododecane tetraacetic acid), labeled with 111 In and purified by gel filtration. Male Sprague‐Dawley rats (n = 4) were anesthetized using subcutaneous ketamine (100 mg/kg) and dexmedetomidine (0.5 mg/kg). A 30G needle connected to PE10 tubing was placed into the cisterna magna. The rats were placed in the MiLabs VECTor4CT SPECT/CT system, a 180‐minute long acquisition was started, simultaneously with the infusion of
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[111In]In‐DOTA‐ovalbumin ([111In]OVA) into the cisterna magna at rate of 2 μL/min. In total, 40 μL [111In] OVA (~12 MBq) was infused. After the scan, the rats were sacrificed, their brains were homogenized in PBS, centrifuged, and supernatant extracts analyzed by size‐ exclusion HPLC. Results [111In]OVA was obtained in 70% radiochemical yield, >97% radiochemical purity and specific activity of over 1 GBq/mg. MicroSPECT imaging showed a significant penetration [111In]OVA to the deeper brain structures after injection in the cisterna magna (Figure 1). The time point of maximum radioactivity in brain was observed at 20–50 min, followed by subsequent slow efflux, with very little activity in the lymph nodes (99%) and chemical purity (no detectable chemical impurity peak from analytical HPLC). Conclusion General cGMP‐compliant protocols for the synthesis of tumor proliferation ([18F]FLT) and hypoxia ([18F]FMISO) imaging agents has been developed; both final drug products boasting high radiochemical and chemical purities. This method, featuring nearly identical parameters to produce both tracers, should be very convenient for adaptation, both manually and automatically, by radiochemists. RE FER EN CES 1. Jun Oh Seung, et al. Nucl Med Biol 2004, 31, 803‐809. 2. Cheung Yiu‐Yin, et al. Appl Rad Isotope 2015, 97, 47‐51. 3. Nandy S. K. et al. J Radioanal Nucl Chem 2010, 286, 241‐248.
Figure 1. The general protocol for the synthesis of [18F]FLT and [18F]FMISO.
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Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-302 | A 99mTc‐labeled cyclic peptide for integrin αvβ6‐targeted SPECT/CT imaging of tumor and pulmonary fibrosis in preclinical mouse models Xun Feng; Hao Liu; Liquan Gao; Jiyun Shi; Bing Jia; Zhaofei Liu; Fan Wang Peking University Health Science Center, China
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Objectives Integrin αvβ6, a member of the integrin family, is present at undetectable levels in normal tissues but is overexpressed during many pathological processes, especially in cancer and fibrosis. Noninvasive imaging of integrin αvβ6 expression using a radiotracer with favorable in vivo pharmacokinetics would facilitate disease diagnosis and therapy monitoring. In this study, we aimed to investigate whether a 99mTc‐labeled cyclic peptide targeting integrin αvβ6 could be used for small‐animal SPECT imaging of tumor and pulmonary fibrosis in animal models.
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Methods Through the disulfide‐cyclized method, we synthesized a new integrin αvβ6‐targeted cyclic peptide (denoted as cHK), and radiolabeled it with 99mTc. The in vitro receptor‐binding specificity and in vivo metabolic stability of the resulting radiotracer 99mTc‐HYNIC‐cHK was tested. The ability of 99mTc‐HYNIC‐cHK to detect integrin αvβ6 expression in pancreatic cancer xenografts and idiopathic pulmonary fibrosis was evaluated in vivo. Results The radiochemical purity of 99mTc‐HYNIC‐cHK was >95% after purification, and the specific activity was >30 MBq/nmol. The binding of 99mTc‐HYNIC‐cHK to BxPC‐3 cells was significantly inhibited by the addition of excess doses of the cHK peptide (from 0.79 ± 0.01 to 0.03 ± 0.005 %AD, P < 0.001). The 99mTc‐HYNIC‐cHK remained stable for more than 4 h both in fetal bovine serum and in the presence of L‐cysteine and retains its chemical integrity at 0.5 h and 1 h postinjection in both blood and urine from normal BALB/c mice. The uptake of 99mTc‐HYNIC‐cHK in BxPC‐3 tumors at 0.5 h after injection (0.63 ± 0.18 vs. 0.58 ± 0.09, P < 0.05) and the tumor‐to‐muscle (T/M) ratio (2.99 ± 0.87 vs.
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1.82 ± 0.27, P < 0.05) were significantly higher than that of 99mTc‐labeled linear peptide. 99mTc‐HYNIC‐cHK showed clear tumor imaging with high contrast to the contralateral background and had an evident accumulation in the lungs of the bleomycin‐induced lung fibrosis mouse model that confirmed by the hematoxylin‐eosin (H&E) and Sirius red (specific for collagen) staining. Conclusions 99m Tc‐HYNIC‐cHK exhibited specific integrin ανβ6‐ targeting ability with demonstrated specific detection of integrin ανβ6 expression in subcutaneous pancreatic cancer xenografts and pulmonary fibrosis in animal models.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-303 | Comparison of [18F]DMFB and [18F] DMPY2 for PET imaging of melanoma Ayoung Pyo; Ye‐Rim Jung; Dong‐Yeon Kim; Jung Joon Min
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Chonnam National University Hwasun Hospital Department of Nuclear Medicine, Republic of Korea
Objectives Malignant melanoma is one of the most mortal cancers because of its very aggressiveness and high metastatic potential. The incidence of this cancer has been increasing worldwide, but there is narrow option for effective treatment. Thus, early detection is very important to improve therapeutic outcome and survival of patients. In this study, we synthesized novel 18F labeled benzamide derivatives (N‐(2‐(dimethylamino)ethyl)‐4‐[18F]fluoro18 benzamide; [ F]DMFB and N‐(2‐(dimethylamino)ethyl)‐ [18F]DMPY2). In this 5‐[18F]fluoropicolinamide; study, we evaluated and compared radiochemical and biological characteristics of 18F labeled probes in B16F10 (mouse melanoma)‐bearing subcutaneous and metastasis models. Methods [18F]DMFB was synthesized from N‐succinimidyl 4‐[18F] fluorobenzoate ([18F]SFB) via two steps. [18F]DMPY2 was synthesized from 5‐bromo‐N‐(2‐(dimethylamino) ethyl)pyridine‐2‐carboxamide as the precursor. At the end of the reaction, the mixture was purified using HPLC. Biodistibution and microPET studies were performed at different time points after i.v. injection of each compound (7.4 MBq) in B16F10 primary and metastasis mouse models. The static images at 30 and 60 min were acquired for 10 min. Results Radiochemical yields of [18F]DMFB and [18F]DMPY2 was approximately 10‐15%. In biodistribution studies, both agents accumulated and were retained in tumor from 10 to 120 min. Tumor uptake of [18F]DMPY2 (10, 30, 60 and 120 min% ID/g: 9.2, 15.8, 24.8, 10.6) was higher than [18F]DMFB (10, 30, 60 and 120 min% ID/g: 9.24, 10.8, 13.0, 10.6). MicroPET study clearly demonstrated that [18F]DMFB and [18F]DMPY2 accumulated in tumor specifically at 10 min after i.v. injection, and tumor was clearly visible with high tumor‐to‐background ratio. Consistent with biodistribution study, [18F]DMFB has lower uptake in B16F10 tumors than [18F]DMPY2. B16F10 lung/lymph node metastasis lesions were clearly visible after injection of [18F]DMPY2 and [18F]DMFB. Conclusion [18F]DMPY2 demonstrated malignant melanoma with higher tumor uptake than [18F]DMFB in B16F10 tumor bearing mice. [18F]DMFB and [18F]DMPY2 successfully visualized lesions in B16F10 lung/lymph node metastasis models. [18F]DMPY2 might have a potential to be utilized as a novel melanoma imaging agent for PET.
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Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-304 |
68
Ga‐labeled non‐blocking nanobody for targeting PET imaging of tumor PD‐L1 expression Gaochao Lv; Ling Qiu; Ke Li; Qingzhu Liu; Jianguo Lin Jiangsu Institute of Nuclear Medicine, China
Objectives Although immunotherapy through the programmed death 1 (PD‐1) and its ligand PD‐L1 show impressive clinical outcomes, not all patients respond to immune checkpoint blockade. Recent studies have demonstrated that high tumor PD‐L1 expression might be most likely to respond to the successful PD‐1/PD‐L1 checkpoint blockade. Herein, a novel 68Ga‐labeled nanobody, namely, [68Ga]NOTA‐Nb109, was developed for imaging PD‐L1 expressing in mouse model bearing melanoma. Methods The nanobody was labeled with 68Ga through a NOTA chelator. An in vitro binding assay was performed to assess the affinity and binding epitope of Nb109 to PD‐L1. [68Ga] NOTA‐Nb109 was evaluated by the biodistribution and micro‐PET imaging on the PD‐L1 positive tumors (A375‐ hPD‐L1) and the negative tumors (MCF‐7). Results The tracer was obtained with >95% radiochemical yield and >98% radiochemical purity in 10 min, which showed a specific high affinity to PD‐L1 with a KD value 2.9 × 10‐9 M. In vitro binding assay demonstrated that Nb109 bind different epitopes with PD‐1, in other words, Nb109 was a non‐blocking nanobody toward PD‐L1. The biodistribution and PET imaging studies indicated that [68Ga]NOTA‐Nb109 showed a specific accumulation in A375‐hPD‐L1 over MCF‐7 tumor with a maximum uptake 5.0 ± 0.35% ID/g at 1 h. The radioactivity washout from the muscle and bloodwas rapid and stable in tumor, resulting in an excellent tumor‐to‐ background contrast at all‐time points over 10 min to 2 h. Conclusions This radiotracer has great potential to evaluate the PD‐L1 status of tumors by micro‐PET imaging studies and may ultimately predict therapeutic effect targeting immune checkpoints. ACKNOWLEDGMENTS This work was financially supported by National Natural Science Foundation of China (21501074) and Natural Science Foundation of Jiangsu Province (BK20151118).
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Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-305 | Preparation, evaluation, and SPECT/ CT imaging of 99mTc‐radiolabeled nanobody for Her2‐positive breast cancer Hongjie Song1,2; Weiling Lian1; Qin Shi1; Ming‐Wei Wang1 1
Fudan University, China; 2 Shanghai Normal University, China
Objectives Human epidermal growth factor receptor 2 (Her2) is overexpressed in 20%‐30% of breast cancers, and Her2‐ targeted drugs have produced great impact on the clinical management of breast cancers. [1, 2] In this study, we aimed to develop 99mTc‐radiolabeled Her2 nanobody and perform in vitro and in vivo evaluation and SPECT/ CT imaging for Her2‐positive breast cancer. Methods Her2 nanobody Nb023 was radiolabeled using the 99m Tc(CO)3(H2O)3 method and monitored by radio‐ITLC. The stability in serum and PBS and in vitro binding affinity were assessed. BT‐474 (Her2 +++), MDA‐MB‐453 (Her2 ++), and MDA‐MB‐468 (Her2 −) Xenografts were built as tumor models with different Her2 expression level. Small animal SPECT/CT imaging was acquired at 30 min and 90 min after injecting 99mTc‐Nb023 (Fig 1 (B)). The quantitative uptake %ID/g of tumor lesions and muscle was measured and the uptake ratios of tumor‐to‐muscle were calculated.
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Results 99m Tc‐Nb023 were prepared via the 99mTc(CO)3(H2O)3 labeling method with high radiochemical yield of about 90%. It showed great stability within 6.0 h in PBS and in serum and high binding affinity to Her2. SPECT/CT imaging demonstrated that Her2‐postive BT‐474 and MDA‐ MB‐453 tumors were clearly mapped with high contrast at both 30 min and 90 min after injecting 99mTc‐Nb023; however, Her2‐negtive MDA‐MB‐468 did not. Quantitatively, 99mTc‐Nb023 exhibited highest uptake in BT‐474 tumor with highest T/M (24) at 90 min, middle uptake in MDA‐MB‐453 tumor with middle T/M (9.4), yet lowest uptake in MDA‐MB‐468 tumor with lowest T/M (1.7). Conclusions Her2‐targeted molecular imaging probe 99mTc‐Nb023 was successful developed using 99mTc(CO)3(H2O)3 labeling method by us. 99mTc‐Nb023 SPECT/CT imaging will be further investigated for the imaging and therapy evaluation of Her2‐postive breast cancer because of its high tumor uptake and unique Her2 targeting. ACKNOWLEDGEMENTS This study was supported by National Natural Science Foundation of China (No. 21771041, No. 11275050). We gratefully thank NanoMab Technology Limited for the assistance on the supply of nanobodies and tumor models. RE FER EN CES 1. Yosef Y, et al. Nat Rev Mol Cell Biol, 2001, 2(2):127‐137. 2. Schettini F, et al. Cancer Treat Rev, 2016, 46:20‐26.
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Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-306 | Novel 99mTc labelled nitroimidazole xanthates as potential tumor hypoxia imaging agents Qing Ruan1; Junbo Zhang1; Xuran Zhang1,2 1
Beijing Normal University, China; 2 China Institute of Atomic Energy,
China
Objectives To obtain an ideal 99mTc labelled nitroimidazole hypoxia imaging agent is still of great interest. Xanthates can be used to produce 99mTcO and 99mTcN complexes on the basis of binding of the groups to four sulfur atoms. This background encouraged us to prepare several 99mTc labelled nitroimidazole xanthates by using different 99m Tc cores to discover good radiotracers for targeting tumor hypoxia. Methods Nitroimidazole xanthate (NMXT) was synthesized and labelled with 99mTc‐nitrido core and 99mTc‐oxo core to produce 99mTcN‐NMXT and 99mTcO‐NMXT, respectively. The products were characterized by HPLC, and their stability and partition coefficients were also determined. Cellular accumulation experiments in S180 cells, biodistribution studies in mice bearing S180 tumor were performed. SPECT/CT imaging was acquired at 2 h after injection. Results The radiochemical purity of the 99mTc complexes was over 95%, and they were stable for 6 h. The cellular uptake exhibited good hypoxic selectivity. 99mTcN‐NMXT and 99mTcO‐NMXT were hydrophilic and the value of log P were −0.65 ± 0.06 and −1.43 ± 0.08, respectively. The evaluation of biodistribution indicated that they could accumulate in tumor. Among them, 99mTcO‐NMXT exhibited higher tumor uptake, 1.93 ± 0.25%ID/g, 1.73 ± 0.14%ID/g at 2 h and 4 h post‐injection, and tumor/muscle ratios was 5.33 and 7.01 at 2 h and 4 h post‐injection. Further, SPECT/CT images indicated clear accumulation in tumor and the value of the region‐of‐ interest (ROI) ratio of the uptake for the tumor site to
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the coresponding non‐tumor region was 6.15 ± 0.97 at 2 h post‐injection. Conclusions In present study, a novel ligand NMXT was synthesized, and its 99mTc‐oxo core and 99mTc‐nitrido core complexes were successfully prepared in high yields through a ligand‐exchange reaction. The preliminary in vivo studies showed both of them had a relative high tumor uptake and good tumor‐to‐muscle ratios. By comparing the two 99m Tc complexes, 99mTcO‐NMXT showed obvious tumor uptake and better target/non‐target ratios, suggesting it would be a potential tracer for hypoxia imaging in tumor. ACKNOWLEDGEMENTS The work was supported by the National Natural Science Foundation of China (21771023) and the project of Beijing Municipal Science and Technology Commission (Z181100002218033). RE FER EN CES 1. Ruan Q. et al. Med Chem Commun 2018; 9, 988‐994 2. Fernández S. et al. Bioorg Med Chem 2012; 20: 4040‐4048
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-307 | Optimizing the molecular design of 68
Ga‐labeled affibody molecules for in vivo PET imaging of HER3 expression Sara Rinne1; Bogdan Mitran1; Joshua Gentry; Anzhelika Vorobyeva1; Charles Dahlsson Leitao2; Ken Andersson2; John Lofblom2; Vladimir Tolmachev1; Anna Orlova1 1
Uppsala University, Sweden; 2 KTH Royal Institute of Technology,
Sweden
Objectives The human epidermal growth factor receptor type 3 (HER3) is a major contributor to cancer development, progression, and resistance to HER‐targeted therapy. HER3 targeting therapies are under active development. Reliable methods to detect elevated HER3 expression
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are required for effective treatment. We previously reported that in a preclinical model gallium‐68 labeled HER3‐targeting affibody molecule ([68Ga]Ga‐(HE)3‐ ZHER3‐NOTA) could visualize HER3 expression.(1) Achieving high imaging contrast continues to be challenging because of relatively low expression of HER3 in the target and natural expression in normal organs, particularly liver. The aim of this study was to optimize the molecular design of HER3‐targeting affibody molecule ZHER3 for PET imaging of HER3 expression using gallium‐68. We therefore investigated the influence of a hydrophilic N‐terminal (HE)3‐tag and the charge and composition of the gallium‐68/chelator‐complexes at C‐ terminus on the biodistribution of ZHER3. Methods Affibody molecules ZHER3‐X and (HE)3‐ZHER3‐X (X=NOTA, NODAGA, DOTA, DOTAGA) were labeled with gallium‐68 in ascorbic acid buffer (1 M, pH 3.6). Stability of metal‐chelator complexes was tested in PBS and human serum. Binding specificity and cellular processing of labeled conjugates were studied in HER3‐expressing cancer cell lines BxPC‐3 and DU145. In vivo specificity and biodistribution of the conjugates were studied 3 h pi in mice bearing BxPC‐3 xenografts. MicroPET/CT imaging was performed 3 h pi to confirm results of the biodistribution. Results (HE)3‐ZHER3‐X, ZHER3‐NOTA, ZHER3‐NODAGA formed stable complexes with gallium‐68 (Table 1). ZHER3‐DOTA and ZHER3‐DOTAGA were labeled with insufficient yields. Only NOTA and NODAGA containing variants were included in further investigation to enable comparison of the (HE)3‐tag influence. Specific binding to HER3 was preserved after labeling, and molecular design had minor influence on in vitro properties. In both cell lines, binding of conjugates to HER3 was rapid, but internalization rate was slow, 95%) and stable in mice serum at least for 2 h (>95%) in vitro and had metabolic stability in urine in vivo. The partition coefficient (Log P) was −2.52 ± 0.33, showing that it was hydrophilic. The uptake of [99mTc‐(CN6DG)6]+ in S180 cells could be inhibited by 2 mg D‐glucose (27%, *P < 0.05), while 2 mg L‐glucose had no significant effect (P = 0.34), demonstrating that its uptake in S180 cells might be mediated by D‐glucose transporters. Biodistribution studies showed that [99mTc‐ (CN6DG)6]+ had high tumor uptake at 30 min post‐injection (2.40 ± 0.08%ID/g) and remained high at 60 min (1.31 ± 0.15%ID/g) and 120 min post‐injection (0.75 ± 0.12%ID/g). The tumor/muscle and tumor/blood ratios at 60 min post‐injection were 6.55 and 4.68, respectively. S180 tumor could be visualized clearly from the SPECT/CT images at 60 min post‐injection. Conclusion [99mTc‐(CN6DG)6]+ showed good physiological and pharmaceutical properties in vitro and in vivo, demonstrating that it had great potential for tumor detection and needs further investigation. ACKNOWLEDGEMENTS The work was supported by the National Natural Science Foundation of China (21771023), the project of Beijing Municipal Science and Technology Commission (Z181100002218033) and the Research Fund for Undergraduates of Beijing Normal University. R EF E RE N C E S 1. Xuran, Z.; Qing, R.; Xiaojiang, D.; et al. Mol. Pharmaceutics 2018, 15, 3417‐3424.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-309 | Caspase‐3 activity‐based PET probes for assessment of early response to cancer therapy Filipe Elvas1; Angelo Solania2; Pieter Van der Veken3; Koen Augustyns3; Steven Staelens4; Sigrid Stroobants; Dennis Wolan2; Leonie Wyffels5 1
University of Antwerp, Belgium; 2 Departments of Molecular and
Experimental Medicine and Chemical Physiology, The Scripps Research Institute, United States; 3 Laboratory of Medicinal Chemistry University of Antwerp, Antwerp, Belgium; 4 Molecular Imaging Center Antwerp University of Antwerp, Antwerp, Belgium; 5 University Hospital Antwerp, Belgium
Objectives Current clinical assessment of treatment response mainly relies on the measurement of late changes in tumor volume assessed by anatomical imaging. An earlier and accurate assessment of response to anticancer therapies can be achieved by readout of treatment induced programmed cell death (apoptosis) in tumors using positron emission tomography (PET) radiotracers that specifically target hallmarks of the apoptosis process such as the activation of caspase‐3. So far, no PET radiotracers have been developed that specifically target this critical component of the execution phase of apoptosis. Herein, we aimed to develop 18F‐labeled activity‐based probes (ABPs) to selectively monitor caspase‐3 activity by PET imaging. Methods To increase selectivity of the caspase‐3 PET probes, we have used the peptide recognition sequence and the
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warhead of the most selective caspase‐3 inhibitor know to date, DW3‐KE (DW3=3Pal‐Asp‐βhLeu‐Phe‐Asp; KE=5‐ methyl‐2‐thiophene carboxylate‐derived ketoester).1 Two probes were developed for radiolabeling: MICA‐304 (DW3‐KE) and MICA‐309 (DW3(OMe)‐KE). DW3‐ derived probe precursors were capped with 5‐hexynoic acid for click radiolabeling. SDS‐PAGE analysis was performed to evaluate binding efficiency and selectivity of the 18F‐labeled ABPs towards human recombinant caspases, cathepsin B and legumain. The partition coefficients (logD values) of the radiotracers were determined experimentally as an indication of their lipophilicity. Radiotracer stability was evaluated in vitro in PBS at 37°C. The pharmacokinetic profile of the MICA‐309 was evaluated by dynamic in vivo small animal PET imaging up to 2 h post i.v. injection of the radiotracer (8 MBq) and ex vivo biodistribution using CD1 nude mice. Results Click radiolabeling with 2‐[18F]fluoroethyl azide was used to obtain the 18F‐labeled radiotracers in 20.8 ± 11.5% (n = 6, decay‐corrected to EOB) and 8.3 ± 3.4% (n = 5, decay‐corrected to EOB) isolated radiochemical yield (RCY) for [18F]MICA‐304 and [18F]MICA‐ 309, respectively. [18F]MICA‐304 showed good in vitro stability at 37°C for up to 120 min, with only isomer formation being detected by radio‐HPLC. After 30 min incubation at 37°C, [18F]MICA‐309 revealed formation of one polar metabolite, with 32% of the radiotracer remaining intact after 120 min. [18F]MICA‐304 (logD = −1.78 ± 0.01) was found to be highly hydrophilic, which generally confers poor cell membrane penetration. In contrast, [18F] MICA‐309 (logD = 1.81 ± 0.13) showed a more lipophilic character, consistent with the neutralization of the negative charge on the molecule conferred by the methyl protection of the free carboxyl groups. Therefore, only [18F] MICA‐309 proceeded for in vivo evaluation. [18F]MICA‐ 304 efficiently detected caspase‐3 within 10 min after incubation and showed no cross‐reactivity against cathepsin B and legumain, as established by SDS‐PAGE. [18F] MICA‐309 exhibited an initial peak uptake of radioactivity in the blood pool (33.39 ± 0.15%ID/mL at 0.5 min), which was immediately followed by a fast decrease reaching a minimum value at 120 min (0.150 ± 0.001%ID/mL). A combination of hepatobiliary and renal clearance of the radioactivity could be detected, with bladder activity dominating at 120 min post‐radiotracer injection (75.28 ± 0.24%ID/mL). The ex vivo biodistribution confirmed a mixed renal‐hepatobiliary clearance with increasing uptake of radioactivity in the small intestine (59.49 ± 6.20%ID/g at 60 min p.i.) and kidneys (7.74 ± 0.57%ID/g at 60 min p.i.). The radiotracer demonstrated low accumulation of radioactivity in the bone, which indicates absence of defluorination.
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Conclusions [18F]MICA‐309 is a candidate ABP for in vivo PET imaging of caspase‐3 activity. We will further evaluate the in vivo stability of [18F]MICA‐309, and the in vivo targeting of therapy‐induced apoptosis in well characterized colorectal and lung cancer xenograft models treated with anticancer therapy. ACKNOWLEDGEMENTS Research Foundation—Flanders (FWO 12T8818N) RE FER EN CES 1. Vickers, C. J.; Gonzalez‐Paez, G. E.; Wolan, D. W., Selective detection and inhibition of active caspase‐3 in cells with optimized peptides. J Am Chem Soc 2013, 135 (34), 12869‐76.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-310 |
89
Zr‐immuno‐PET and biodistribution preclinical studies to compare the tumor targeting of the novel anti‐CD166 probody drug conjugate CX‐2009 and its parental derivatives in a lung cancer xenograft mouse model. Marion Chomet1; Maxime Schreurs2; Olga Vasiljeva3; Margaret Nguyen3; Guus van Dongen4; Danielle Vugts5 1
Amsterdam UMC, VU University, Radiology and Nuclear Medicine,
Netherlands; 2 Amsterdam UMC, Netherlands; 3 CytomX Therapeutics Inc., United States; 4 VU University Medical center, Netherlands; 5
Amsterdam UMC, VU University, Netherlands
Objectives ProbodyTM therapeutics are fully recombinant masked monoclonal antibodies (mAbs) that become activated (demasked) by proteases present in the tumor environment.[1] This innovative approach, designed to improve the selectivity of tumor targeting, is particularly attractive in the context of Antibody Drug Conjugate (ADC)‐based therapy, where target‐mediated toxicity in healthy organs constitutes a major limitation and narrows the therapeutic window.[2] CX‐2009 is an investigational novel Probody Drug Conjugate (PDC) with the toxic drug DM4 coupled to a Probody molecule targeting CD166. CD166 is an antigen overexpressed by multiple tumor types, but is also present in several healthy organs.[3] By performing 89Zr‐immuno‐PET and biodistribution studies in nude mice bearing CD166‐positive H292 lung cancer xenografts, we aim to compare the in vivo tumor targeting efficiency of CX‐2009 with its corresponding investigational parental mAb (CX‐090), its investigational Probody counterpart without DM4 (CX‐191) and its investigational unmasked ADC counterpart (CX‐1031).
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Methods CX‐2009, CX‐090, CX‐191, and CX‐1031 were modified at 37°C for 30 min with 5 equivalents of DFO‐NCS, followed by removal of excess chelator and radiolabeling with 89Zr for 1 h at room temperature at pH 7.[4] After PD10 purification, the investigational products were formulated in 20mM‐L‐histidine/240mM‐sucrose/0.01%‐ tween‐20 (pH 5.4‐5.6). The radioactive constructs were analyzed by size‐exclusion HPLC and spin‐filter for their protein integrity, radiochemical purity, and binding assays to check immunoreactivity. DM4 release from the PDC and ADC was assessed by HPLC using the ratio between the peak area at 252/280 nm. The conjugates (each at 10, 110, or 510 μg) were injected into H292 tumor bearing mice (n = 5 per group). Biodistribution was assessed at 24, 72, and 168 h p.i. and four mice of the 110 μg groups of each construct were imaged by PET/CT at 24 and 72 h p.i. Results [89Zr]Zr‐CX‐2009, [89Zr]Zr‐CX‐090, [89Zr]Zr‐CX‐191, and [89Zr]Zr‐CX‐1031 conjugates with a radiochemical purity above 95% and preserved antigen binding were obtained (>70% for all constructs). In addition, no DM4 drug release was observed upon conjugation and radiolabeling. In vivo, [89Zr]Zr‐CX‐2009 at the 110 μg dose, presented at 72 h p.i. a tumor uptake of 21.8 ± 2.3%ID/g, which was not significantly different in comparison with [89Zr]Zr‐ CX‐191 (21.8 ± 5.0), [89Zr]Zr‐CX‐1031 (18.7 ± 2.5), and [89Zr]Zr‐CX‐090 (20.8 ± 0.9%ID/g), respectively. Similar uptake of the four constructs with SUVs in the tumors of 4.8 ± 0.7 for [89Zr]Zr‐CX‐2009 (PDC), 4.8 ± 0.4 for [89Zr]Zr‐CX‐191 (Probody therapeutic), 4.8 ± 0.8 for [89Zr]Zr‐CX‐1031 (ADC), and 4.9 ± 0.6 for [89Zr]Zr‐CX‐ 090 (mAb) was observed in quantitative PET imaging. Increasing the dose with unlabeled drug to saturating levels (510 μg) was associated with lower tumor uptake and higher blood values for all constructs, while decreasing the dose (10 μg) was associated with increased variation in tumor uptake within and between groups. Conclusion By using 89Zr‐immuno‐PET, we demonstrated the potential of the novel PDC CX‐2009 to target CD166 expressing tumors in vivo with similar efficiency as its corresponding parental antibody, Probody therapeutic and ADC. Thus, the enzymatic activation required inside the tumor microenvironment to allow CD166 binding does not seem to limit the in vivo tumor targeting performance of the PDC. Furthermore, the attachment of the drug DM4 was not associated with an effect on tumor targeting. As those compounds are not cross‐reactive with mouse CD166; however, reduced targeting of healthy organs should be further confirmed in the clinical 89Zr‐ immuno‐PET studies that are planned.
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RE FER EN CES 1. Wong K.R. et al, Biochimie, vol.122, pp.62–67, 2016. 2. Carmon K.S., Azhdarinia A., Mol Imaging, vol.17, pp.1‐10, 2018. 3. Lin J., Sagert J., Innovations for Next‐Generation Antibody Drug Conjugates, Damelin M., Ed. Cham: Springer International Publishing, pp 281–298, 2018. 4. Vosjan M.J.W.D. et al., “Nat Protoc, vol.5, no.4, pp.739–743, 2010. PROBODY is a trademark of CytomX Therapeutics, Inc. All other brands and trademarks referenced herein are the property of their respective owners.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-311 | Bispecific GRPR‐PSMA radiotracers for prostate cancers Ayman Abouzayed1; Cheng‐Bin Yim2; Bogdan Mitran1; Sara Rinne1; Mats Larhed3; Vladimir Tolmachev1; Ulrika Rosenström1; Anna Orlova1 1
Uppsala University, Sweden; 2 Turku PET Centre, Finland; 3 Department
of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Sweden
Objectives The majority of prostate cancers overexpress Gastrin‐ Releasing Peptide Receptors (GRPR) and Prostate Specific Membrane Antigens (PSMA). The ability to target both GRPR and PSMA using one bispecific radiotracer could improve the sensitivity of detecting prostate cancer and its metastases and benefit the therapeutic outcome. The aim of this study was to evaluate three radioiodinated GRPR‐PSMA bispecific heterodimers based on a PSMA inhibitor and a GRPR antagonist (Figure 1A) in vitro and in vivo, and select a promising peptide for theranostic applications (iodine‐123 for SPECT, iodine‐124 for PET, or with iodine‐131 for therapy). Methods BO‐0530, BO‐0535, and BO‐0536 were synthesized by solid phase peptide synthesis. The heterodimers were labelled with 125I using Iodogen. In vitro on stability and octanol‐water partition coefficient of the radiolabelled heterodimers were evaluated. Binding specificity and IC50 were determined using PC‐3 (GRPR+/PSMA‐), LNCaP (GRPR‐/PSMA+), and PC‐3pip (GRPR+/PSMA +) cells. In vivo specificity for all three peptides was studied 1 h pi in mice bearing PC‐3 and LNCaP xenografts using 40 pmol of the radiolabelled peptide for the non‐ blocked groups or along with 8 nmol of either unlabelled PSMA‐617 or unlabelled PEG2‐RM26 for the blocked groups.
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Results The labelling radiochemical yield (RCY) was 76% for [125I]I‐BO‐0530, 71% for [125I]I‐BO‐0535, and 75% for [125I]I‐BO‐0536. The molar activity was 1.1 MBq/nmol, 2.9 MBq/nmol, and 3 MBq/nmol, respectively. The RCY for [125I]I‐BO‐0530 decreased to 52% when the molar activity was increased to 13 MBq/nmol. The radiolabelled heterodimers were separated on HPLC and further purified using Sep‐Pak C8 cartridges. All three peptides bound specifically to GRPR and PSMA and were stable in human and mouse sera when tested up to 24 hours. The logp values for [125I]I‐BO‐0530, [125I]I‐BO‐0535, and [125I]I‐BO‐0536 were −0.52, 0.47, and −0.18, respectively, indicating that BO‐535 is the most lipophilic while BO‐ 0530 is the least lipophilic. The IC50 values for BO‐0530, BO‐0535 and BO‐0536 were 17.7 nM, 24.9 nM, and 7.8 nM towards GRPR and 124 nM, 127 nM, and 95 nM towards PSMA, respectively. The in vivo specificity test (Figure 1B) showed that while all heterodimers were capable of specifically binding to PSMA, only [125I]I‐BO‐ 0530 preserved binding to GRPR. However, all heterodimers demonstrated specific binding to murine GRPR in pancreas. All three labelled heterodimers had high liver uptake that correlated with their degree of lipophilicity. Undesirable hepatic uptake could create problems both in imaging and radiotargeting therapy and measures should be taken to decrease lipophilicity of heterodimers
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in future molecular design. Renal reabsorption was high for less lipophilic dimers BO‐0535 and BO‐0530; however, renal uptake was PSMA mediated for all dimers. Conclusion All three newly synthesized PSMA/GRPR heterodimers have specific binding to GRPR and PSMA in vitro. However, only [125I]I‐BO‐0530 demonstrated specific binding to both receptors in vivo. The biodistribution of [125I]I‐ BO‐0530 will be further studied over time. ACKNOWLEDGMENTS This work was supported by the Swedish Cancer Society (CAN2014‐474 and CAN 2017/425) and the Swedish Research Council (2015‐02509).
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-312 | Abstract withdrawn
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Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-313 | Synthesis and biological evaluation of a furin‐activatable molecular probe for PET imaging of breast cancer Ling Qiu; Qingzhu Liu; Ke Li; Gaochao Lv; Jianguo Lin Jiangsu Institute of Nuclear Medicine, China
Objectives Peptide analogues have attracted considerable attention in the field of developing novel positron emission tomography (PET) imaging agents due to their unique properties. Nevertheless, the complicated radiolabelling process and fast metabolism usually make the clinical application of peptide‐based molecular probes challenging. To overcome these shortcomings, a novel PET probe based on the peptide sequence Arg‐Val‐Arg‐Arg (RVRR), Acetyl‐ Arg‐Val‐Arg‐Arg‐Cys (StBu)‐Gly(18F‐AmBF3)‐CBT (18F‐ 1), was designed and radiosynthesized using a simple and convenient one‐step 18F‐fluorination procedure. The smart probe can be activated by the protease furin and then undergoes an intermolecular cyclization reaction in tumor cells, resulting in enhanced PET imaging efficiency of tumor. Methods The radiosyntheses of the target probe 18F‐1 and the control probe 18F‐1‐ctrl were performed under facile conditions in pyridazine‐HCl buffer (pH~2.5) at 80 °C within 30 min. The enzyme‐controlled condensation was studied for the cold probe 1 in the human breast cancer cell lysates (MDA‐MB‐468). The cellular uptake of 18F‐1 and 18 F‐1‐ctrl was studied and compared by measuring the radioactivity in MDA‐MB‐468 cells using a γ‐counter after incubation with 1 μCi of 18F‐1 or 18F‐1‐ctrl, respectively. In vivo behavior of 18F‐1 was examined through PET imaging of MDA‐MB‐468 tumor‐xenografted mice and compared to that of 18F‐1‐ctrl and co‐injection of 18F‐1 with cold probe 1. Results The probe 18F‐1 was obtained with a high radiochemical yield (RCY) of 65.3 ± 1.75% and an excellent radiochemical purity (RCP > 99%). Under the activation of furin and GSH, the probe suffered a condensation reaction to form dimers and then self‐assembled into nanoparticles to
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produce enduring signal. The cellular uptake of 18F‐1 and 18 F‐1‐ctrl was determined to be 10.2 ± 0.37 and 1.19 ± 0.25%ID at 120 min, respectively. As for in vivo PET imaging, 18F‐1 exhibited a tumor uptake of 2.39 ± 0.31%ID/g and a tumor‐to‐muscle uptake ratio of 2.93 ± 0.92 after injection of 10 min. The co‐injection of 18 F‐1 and 1 resulted in a stable tumor uptake ranging from 2.83 ± 0.23% ID/g to 3.40 ± 0.18% ID/g within 60 min post injection. Conclusions The one‐step 18F‐labeling method for preparing the probe 18 F‐1 shows advantages in simplifying the radiolabeling process with high RCY and short time, which enables a real kit process for the synthesis of 18F‐radiopharmaceuticals and is significant for the large scale production of clinical applications. The PET imaging results suggest that the probe 18F‐1 has a good tumor uptake and the co‐injection of 18F‐1 with 1 enhances the imaging signal in tumor. ACKNOWLEDGMENTS This work was financially supported by National Natural Science Foundation of China (21701062), Natural Science Foundation of Jiangsu Province (BK20151118, BK20181128), 333 Project of Jiangsu Province (BRA2016518) and Jiangsu Provincial Medical Youth Talent (QNRC2016626, QNRC2016629).
labeled peptide conjugates. For standard purpose, non‐ radioactive natGa‐DOTA‐β‐Ala‐peptides were prepared with yields >27%. High stability as well as negligible transchelation were observed for [68Ga]Ga‐DOTA‐β‐Ala‐ peptides in vitro. However, in vivo stability studies indicated that [68Ga]Ga‐DOTA‐β‐Ala‐KK10 displayed fast degradation in mice blood, while [68Ga]Ga‐DOTA‐β‐Ala‐ KK13 held high stability. Determination of octanol/water partition coefficients suggested that [68Ga]Ga‐DOTA‐β‐ Ala‐KK13 had high hydrophilicity (LogD7.4 = −2.32). Binding affinities of β‐Ala‐KK13 and their derivatives were studied by competition assays in murine 4T1 cells (HER2+), human MDA‐MB‐453 cells (HER2+), and human MCF‐7 cells (HER2‐). DOTA‐β‐Ala‐KK13 demonstrated high binding affinities on HER2+ cells. Linking the chelate unit at the peptide was accompanied by marginal loss of affinity. The saturation study with [68Ga]Ga‐ DOTA‐β‐Ala‐KK13 in 4T1 and MDA‐MB‐453 cells resulted in Kd values in the lower nanomolar range. Thus, [68Ga]Ga‐DOTA‐β‐Ala‐KK13 is a promising radiotracer for further investigations in animal breast cancer models.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging)
P-315 | Direct‐labeling of iron oxide
P-314 | A novel 68Ga labeled peptide conjugate for potential use in imaging of HER2‐positive breast cancer Feng Gao; Weijing Tao
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g )
nanoparticles with zirconium‐89 and its biological application in targeting of cancer cells Pyeong Seok Choi2; Jun Young Lee1; Chirag Vyas1; Young Bae Kong2; Eun Je Lee2; Ho Seung Song2; Seung dae Yang1; Min Goo Hur2; Jeong Hoon Park1 1
Korea Atomic Energy Research Institute, Korea, Republic of; 2 KAERI,
Department of Medical Imaging, Jinling Hospital, China
Korea, Republic of
The human epidermal growth factor receptor‐2 (HER2), overexpressed in some breast cancer tissues, is an attractive target for imaging or treatment of this type of malignancies. In this study, two peptides: KK‐10, a linear peptide with 10 amino acids (Lys‐Ser‐Pro‐Gln‐Pro‐Arg‐ Trp‐Gly‐Ser‐Lys‐NH2) and KK‐13, a lactam bridge‐ cyclized peptide with 13 amino acids (Gln‐Tyr‐His‐cyclo (Lys‐Ser‐Pro‐Asn‐Pro‐Arg‐Phe‐Gly‐Ser‐Lys)) were engineered with β‐Ala linker and conjugated with DOTA‐NHS at N‐terminal, yielding DOTA‐β‐Ala‐peptides. DOTA‐β‐Ala‐peptides were labeled with 68Ga in sodium acetate buffer (0.1M, pH 4.0) at 50°C for 15 min and the radiochemical purity was >96% for both 68Ga
Nanoparticles having the properties to target cancer cells by enhancement of the permeability and retention (EPR) effect have been applied to study in vivo tumor diagnosis and treatment. The utilization of zirconium‐89 (89Zr) with the nanoparticles can assist tracking their pharmacokinetics from its relatively long half‐life (t1/ 89 Zr ions 2 = 78.4 h). Here, in this study, we synthesized labeled iron oxide nanoparticles through a simple one‐ pot direct‐labeling synthesis method that combined 89Zr with the nanoparticles during their crystal growth. The rice‐shaped iron oxide nanoparticles having an average length and width of 180 and 80 nm, respectively, were obtained after 24 h of hydrothermal reaction with 89Zr,
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FeCl3 and glutamic acid. As a result, a higher 89Zr‐labeling yield with the iron oxide nanoparticles (≥99%) was obtained, and its stability was significantly higher (≥99%) in physiological environment for the span of a week as compared with that of post‐labeling methodology of 89Zr on the nanoparticles. The biological studies for in vitro cell uptake showed that the synthesized nanoparticles rapidly internalized in cancer cells and increased over the incubation time. The PET images indicated that 89 Zr labeled iron oxide nanoparticles targeted the CT‐26 tumor site after intravenous injection. To conclude, 89Zr was effectively labeled in the iron oxide nanoparticles during self‐assembly synthesis of the nanoparticles, which is highly stable in biological environments without active toxicity. The radioactive nanoparticles have a possible applicability for PET. R EF E RE N C E 1. Kunjachan, S. et al. Chem Rev 2015; 115: 10907‐10937. 2. Sun, X. et al. Acc Chem Res 2015; 48: 286‐294.
ACKNOWLEDGMENTS This research was supported by the Nuclear R&D Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT and Future planning (2015M2A2A4A02043265, 2015M2C2A1047699 and 2016M2B2A4908558).
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-316 | Radiolabelling and preliminary evaluation of 89Zr‐DFO‐denosumab, a novel antibody‐based radiopharmaceutical for imaging the receptor activator of the nuclear factor k B ligand (RANKL) in the tumour microenvironment. Jonatan Dewulf1; Filipe Elvas2; Tim van den Wyngaert2 1
Antwerp University Hospital, Belgium; 2 University of Antwerp, Belgium
Objectives RANKL is a cytokine from the TNF family that binds the RANK receptor and the natural decoy receptor osteoprotegerin. RANKL is expressed on many tissues (bone, breast, muscle, thymus, lymph nodes, immune cells, liver, intestine) and exists in soluble and transmembrane form. The most essential role of RANKL is osteoclastogenesis and bone remodelling. In current clinical
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practice, anti‐RANKL targeted treatments (e.g., denosumab) are used in age and cancer related bone diseases. However, RANKL is an emerging target in tumour promotion and proliferation, as well as tumour immunology. RANKL expression in the tumour microenvironment (TME) is associated with poor prognosis and more aggressive disease, yet current research is hampered by the lack of non‐invasive longitudinal biomarkers of RANK/ RANKL interaction in the TME. We aimed to radiolabel the anti‐RANKL monoclonal IgG2 antibody denosumab (147 kDa) for immuno‐positron emission tomography (PET) imaging of RANKL in the tumour microenvironment. Methods The radiolabelling of denosumab was facilitated by the use of the “gold standard” chelator to label antibodies with 89Zr desferrioxamine (DFO) and performed as follows: after purification of commercially available clinical grade denosumab (XGEVA®, Amgen) 5 mg/mL of pH adjusted (8.8‐9) antibody solution was added to 5 molar excess of p‐SCN‐Bn‐DFO dissolved in DMSO. The reaction mixture was kept for 1 h at 37°C. Then the conjugated antibody was purified using a PD‐10 (50 kDa cut off) column and evaluated with non‐reduced SDS PAGE to check the antibody integrity. The radiolabelling was executed by adding 350 μg DFO‐conjugated denosumab to neutralized 89Zr‐oxalate solution (2.0 mCi) and reacting for 1 h at 37°C. The radiolabelling yield was evaluated at different time points during the labelling. Quality control of the final radiopharmaceutical was executed by radio‐iTLC. Stability evaluation of the radiotracer was executed in human and mouse plasma at 37°C, and in saline solution at room temperature. Further experiments will assess the preservation of the affinity of radiolabelled denosumab using an in vitro binding assay, and an in vivo biodistribution study of 89Zr‐DFO‐ denosumab in non‐tumour bearing mice will be performed to determine optimal timepoints for imaging with respect to background clearance. Results The SDS PAGE results showed no degradation of denosumab due to conjugation with DFO as seen by no difference in molecular weight between the unmodified native and conjugated antibody (Fig 1A). In addition, no degradation nor aggregation of the antibody was observed. The crude radiochemical yield was 76% after 1 h reaction. After purification with PD‐10, the radiochemical purity of the final solution was greater than 99% (Fig 1B). All iTLC tests were confirmed by gamma counting of the iTLC silica strips. No radiotracer degradation was observed up to 3 days in saline solution (stability > 99%). The stability of 89Zr‐DFO‐denosumab in human and mice plasma was >89% after 3 days
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Figure 1: Non‐reduced SDS PAGE (A), the iTLC of the final radiotracer (B), and the stability of the radiotracer in saline, mouse plasma and human plasma (C).
of incubation (Fig 1C). The pH of the radiotracer solution was 6.5. The in vitro binding affinity, and in vivo biodistribution of 89Zr‐DFO‐denosumab will be evaluated. Conclusions A new immuno‐PET imaging agent 89Zr‐DFO‐ denosumab was successfully synthesized and radiolabelled in good radiochemical yield. Further radiolabelling optimization will be performed to increase the radiochemical yield. The radiotracer showed no signs of degradation in solution and favourable stability for up to three days in mouse and human plasma.
RE FER EN CES 1. Price Eric W., Carnazza Kathryn E., Carlin Sean D., et al. 89Zr‐ DFO‐AMG102 Immuno‐PET to determine local hepatocyte growth factor protein levels in tumours for enhanced patient selection. J Nucl Med 2017; 58:1386‐1394 2. Lacey David L., Boyle William J., Scott Simonet W., et al. Bench to bedside: elucidation of the OPG‐RANK‐RANKL pathway and the development of denosumab. Nat Rev Drug Discov https:// doi.org/10.1038/nrd3705 3. Ahern Elizabeth, Smyth Mark J., Dougall William C., et al. Roles of the RANKL‐RANK axis in anti‐tumour immunity‐implications for therapy. Nat Rev Clin Oncol https://doi.org/10.1038/s41571‐ 018‐0095‐y
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Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-317 | Preparation of 68Ga‐labeled carbonic anhydrase IX (CAIX) ligands via CBT/1,2‐ aminothiol click reaction for tumor hypoxia imaging Kuo‐Ting Chen1; Yann Seimbille1,2 1
Erasmus MC, Department of Radiology & Nuclear Medicine,
Netherlands; 2 TRIUMF, Canada
Objectives Carbonic anhydrase IX (CAIX) is a promising extracellular biomarker of hypoxia in certain malignancies. Several CAIX‐targeted small molecules, such as acetazolamide (AAZ) and benzenesulfonamide, have been radiolabeled to noninvasively image CAIX expression in tumors.1–3 However, target specificity and pharmaceutical profile of the current probes still have to be optimized. Thus, structurally diverse molecules could provide useful information for further probe optimization via the comparison of their physicochemical properties. We described herein the design and synthesis of a small library of 68Ga‐labeled CAIX ligands through a rapid and regioselective 2‐cyanobenzothiazole (CBT)/ 1,2‐aminothiol click reaction to investigate the effect of their molecular composition, solubility, and overall charge on biodistribution.4 Methods We functionalized the commercially available 2‐cyano‐6‐ hydroxybenzozthiazole (6‐OH‐CBT) at the 6‐position by conjugation with macrocyclic intermediates to give three novel CBT‐bearing chelators, NODA‐PyCBT (1), NODAGA‐CBT (2) and DOTA‐CBT (3). The precursors 1‐3 were radiolabeled with 68Ga in a NaOAc buffer at different pH values (pH 3.5‐6.5) and temperatures (25‐90°C) for 15 min. Two CAIX ligands, Cys‐DRD‐AAZ (4) and Cys‐PEG‐AAZ (5), containing an acetazolamide moiety, a spacer and a N‐terminal cysteine residue were prepared by solid‐phase synthesis. The CBT/1,2‐aminothiol cycloaddition was performed by mixing [68Ga]‐1, [68Ga]‐2 or [68Ga]‐3 with 4 or 5 in an aqueous solution (PBS, pH 9.0) at room temperature for 20 min. The stability of the radiolabeled ligands was tested by incubation in PBS buffer or EDTA solution at 37°C for 2 h. The reactions and stability tests were monitored by RP‐C18 HPLC. Results The CBT‐bearing precursors 1, 2, and 3 were obtained from 6‐OH‐CBT with overall yields of 52, 61, and 64%, respectively. [68Ga]‐labeling was performed under optimized reaction conditions (NaOAc buffer, pH 5.5, 90°C,
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15 min) to provide [68Ga]‐1, [68Ga]‐2, and [68Ga]‐3 in high RCYs (>95 %). CAIX ligands 4 and 5 were obtained with respective yields of 32 and 37% by solid phase synthesis. Cross‐ligation of the two series of compounds yielded six new 68Ga‐labeled CAIX ligands ([68Ga]Ga‐NODAPy‐ Luc‐DRD‐AAZ, [68Ga]Ga‐NODAPy‐Luc‐PEG2‐AAZ, [68Ga]Ga‐ [68Ga]Ga‐NODAGA‐Luc‐DRD‐AAZ, [68Ga]Ga‐DOTA‐Luc‐ NODAGA‐Luc‐PEG2‐AAZ, 68 DRD‐AA, and [ Ga]Ga‐DOTA‐Luc‐PEG2‐AAZ) in 20 min with RCYs over 95%. All the radiolabeled products were found to be stable in PBS and EDTA solution for 2 h. Conclusions The orthogonal CBT/1,2‐aminothiol click reaction has been conveniently and efficiently applied to site‐specific 68 Ga‐labeling of novel CAIX ligands. Our synthetic strategy provides versatility in developing new specific targeted imaging probes. Further bioevaluation to explore the effects of the molecular composition on the physicochemical properties is currently underway. ACKNOWLEDGMENTS We gratefully acknowledge the Leenaards Foundation (grant # 3699), NSERC and Erasmus MC for financial support. RE FER EN CES 1. Lau, J.; Lin, K. S.; Benard, F. Theranostics 2017, 7, 4322. 2. Sneddon, D.; Niemans, R.; Bauwens, M.; Yaromina, A.; van Kuijk, S. J.; Lieuwes, N. G.; Biemans, R.; Pooters, I.; Pellegrini, P. A.; Lengkeek, N. A.; Greguric, I.; Tonissen, K. F.; Supuran, C. T.; Lambin, P.; Dubois, L.; Poulsen, S. A. J Med Chem 2016, 59, 6431. 3. More, K. N.; Lee, J. Y.; Kim, D. Y.; Cho, N. C.; Pyo, A.; Yun, M.; Kim, H. S.; Kim, H.; Ko, K.; Park, J. H.; Chang, D. J. Bioorg Med Chem Lett 2018, 28, 915. 4. Chen, K. T.; Ieritano, C.; Seimbille, Y. Chem Open 2018, 7, 25\6.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-318 | Pre‐clinical evaluation of a novel [18F]‐ labeled d‐TCO amide derivative for bioorthogonal pretargeted imaging of cancer Eduardo Ruivo1; Filipe Elvas1; Christel Vangestel2; Frank Sobott3; Steven Staelens2; Sigrid Stroobants1; Pieter Van der Veken4; Leonie Wyffels5; Koen Augustyns4 1
University of Antwerp, Belgium; 2 Molecular Imaging Center
AntwerpUniversity of Antwerp, Antwerp, Belgium; 3 Biomolecular and Analytical Mass SpectrometryUniversity of Antwerp, Antwerp, Belgium; 4
Laboratory of Medicinal ChemistryUniversity of Antwerp, Antwerp,
Belgium; 5 University Hospital Antwerp, Belgium
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Objectives Bioorthogonal chemistry has found rapidly growing applications in the field of molecular imaging. Considerable research has been devoted to the development of antibody‐trans‐cyclooctene (TCO) conjugates, and their application for pretargeted tumor imaging has been reported under different modalities. However, it has been shown that TCO has the tendency to isomerize to its isomer, cis‐cyclooctene (CCO), after prolonged exposure to physiological conditions. Given this, we envisaged a different approach where the development of more stable [18F]‐labeled TCOs is investigated for pretargeted PET imaging using a tetrazine‐modified antibody. Methods Synthesis and characterization by NMR and high‐resolution mass spectrometry of all compounds were performed. Antibody CC49 (anti TAG‐72) was modified with an “in house” tetrazine [1] and analyzed by SDS‐PAGE and mass spectrometry to determine the degree of labeling. Rate constants for the reaction between d‐TCO and tetrazine were measured by stopped‐flow under aqueous conditions. Tracer in vitro stability was evaluated in PBS and mouse plasma at 37°C. In vivo and ex vivo biodistribution studies were performed in nude mice by IV administration of 0.25 mCi of tracer and a whole‐body dynamic (0‐60 min postinjection) scans were acquire. In vivo and ex vivo PET/CT pretargeted imaging was carried out in human colorectal tumor xenografts where CC49‐tetrazine (150 μg/100 μl) and CC49 (100 μg/100 μl; control) were administered IV followed 24 h later by [18F]d‐TCO (0.25 mCi) injection. A whole‐body (60 min postinjection) static scan was acquired. Results The novel d‐TCO reacted with the tetrazine at a rate constant (k2) of 10 553 M‐1 s‐1. The radiolabeling of d‐TCO with [18F] provided a radiochemical yield (RCY) of 5.5 ± 0.5% (decay corrected to EOB) and >98% radiochemical purity. The tracer presented a moderate lipophilicity with a logD value 1.73 ± 0.01. The tracer showed no isomerization after incubation with PBS and plasma up to 2 h and 1 h, respectively. The in vivo stability study showed that 25% of the tracer was intact at 5 min p.i. In control mice, the tracer showed mixed hepatobiliary and renal clearance, displaying at 2 h p.i 0.44 ± 0.03%ID/g in the blood, 4.85 ± 0.17%ID/g in the small intestine, 5.05 ± 0.20%ID/g in the large intestine and 1.31 ± 0.09%ID/g in the kidneys. In tumor xenografts, the average uptake in the tumors was 2.1 ± 0.7%ID/g at 60 min p.i. when pre‐injected with CC49‐ tetrazine and 0.7 ± 0.1%ID/g p.i. when pre‐injected with CC49 (control). A higher tumor uptake could be observed when the mice were treated with CC49‐tetrazine when compared with the control. Furthermore, the tumor‐to‐ muscle ratio was 2.5 ± 0.11.
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Figure 1 Pretargeted PET/CT imaging of tumor‐bearing mice 1h after injection of [18F]d‐TCO.
Conclusions We developed a new [18F]‐d‐TCO tracer that showed good stability with fast reaction kinetics towards tetrazine and a favorable pharmacokinetic profile for pretargeting approaches. We were also able to demonstrate the successful use of a new [18F]‐labeled d‐TCO in a PET pretargeted imaging approach, allowing visualization of the tumor with a significant higher uptake when compared to the control. With this approach, we are able to avoid the prolonged exposure of TCO to plasma proteins leading to its deactivation. Furthermore, thinking about future in vivo applications, having a more hydrophobic‐ labeled TCO can bring advantages when cell membranes and blood‐brain barrier need to be crossed. RE FER EN CES 1. Maggi A. and Ruivo EFP, Development of a Novel Antibody‐ Tetrazine Conjugate for Bioorthogonal Pretargeting. Org Biomol Chem, 2016,14, 7544‐7551, https://doi.org/10.1039/C6OB01411A.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-319 | Fluorine‐18 labeling of an anti‐HER2 sdAb with 6‐fluoronicotinyl moiety via the inverse electron‐demand Diels‐Alder reaction (IEDDAR) including a renal brush border enzyme‐cleavable linker Zhengyuan Zhou1; Michael Zalutsky2; Ganesan Vaidyanathan2
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Duke University, United States; 2 Duke University Medical Center, United States
Objectives Single domain antibody fragments (sdAbs) are now considered as useful platform for labeling with the short‐
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lived positron emitters such as 18F due to their low molecular weight, which results in rapid tumor uptake and fast whole body clearance. However, high levels of renal activity from labeled sdAbs are a significant problem. Previously, we labeled a HER2‐specific sdAb, 2Rs15d with
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F using an [18F]AlF‐NOTA moiety via the tetrazine (Tz)/trans‐cyclooctene (TCO) [4 + 2] inverse electron demand Diels−Alder cycloaddition reaction (IEDDAR) with a renal brush border enzyme (BBE)‐cleavable linker included in the prosthetic group ([18F]AlF‐NOTA‐Tz‐ TCO‐GK‐2Rs15d; Figure 1A; DOI: 10.1021/acs. bioconjchem.8b00699). While significantly (>15 fold) lower kidney activity levels were achieved for [18F]AlF‐ NOTA‐Tz‐TCO‐GK‐2Rs15d compared to those for a non BBE‐cleavable linker‐containing control, tumor uptake was moderate, suggesting that [18F]AlF‐NOTA was not very residualizing. To investigate whether a fluoronicotinyl moiety will result in higher tumor uptake, we modified the above approach by replacing [18F]AlF‐ NOTA with the 6‐[18F]fluoronicotinyl (FN) group. Methods Another HER2‐specific sdAb, 5F7, was derivatized with TCO‐GK‐PEG4‐NHS and then coupled with 6‐[18F] fluoronicotinyl‐PEG4‐methyltetrazine ([18F]2), which was synthesized from N,N,N‐trimethyl‐5‐((2‐(2‐(2‐(2‐(4‐(6‐ methyl‐1,2,4,5‐tetrazin‐3‐yl)phenoxy)ethoxy)ethoxy)ethoxy)ethyl)carbamoyl)pyridin‐2‐aminium triflate (1), by IEDDAR (Figure 1B). For comparison, 5F7 also was labeled using the validated residualizing agent, N‐succinimidyl 3‐ guanidinomethyl‐5‐[125I]iodobenzoate (iso‐[125I]SGMIB; http://dx.doi.org/10.1016/j.nucmedbio.2014.07.005). Radiochemical purity (RCP) was determined by SDS‐PAGE and immunoreactive fraction (IRF) by the Lindmo method. HER2‐binding affinity and paired label (18F/125I) cell uptake assays were performed on HER2‐expressing SKOV‐3 human ovarian carcinoma cells. Paired label biodistribution was performed in athymic mice bearing SKOV‐3 xenografts. Results The intermediate [18F]2 was synthesized from precursor 1 in 44.8 ± 3.5% yield. [18F]FN‐Tz‐TCO‐GK‐5F7 was obtained in 76.0% RCY for IEDDAR and its RCP was >99% by SDS‐PAGE; KD and IRF were 5.4 ± 0.7 nM and 77.5%, respectively. Uptake of [18F]FN‐Tz‐TCO‐GK‐ 5F7 in SKOV‐3 cells in vitro was 2.4 ± 0.2%, 2.3 ± 0.3%, and 2.6 ± 0.1% of input activity at 1, 2, and 4 h, respectively. Significantly higher values were obtained for co‐ (25.9 ± 1.5%, incubated iso‐[125I]SGMIB‐5F7 32.6 ± 2.3%, and 40.8 ± 0.8%). Unlike the in vitro results, SKOV3 xenograft uptake of [18F]FN‐Tz‐TCO‐GK‐5F7 (2.6 ± 2.0%ID/g and 3.7 ± 1.4%ID/g at 1 and 3 h) was not significantly different from co‐injected iso‐[125I] SGMIB‐5F7 {2.0 ± 2.2%ID/g and 6.5 ± 2.6%ID/g, respectively (P > 0.05)}. Because of the 7‐fold lower levels of 18 F in kidneys, tumor‐to‐kidney ratios (T:K) for [18F]FN‐ Tz‐TCO‐GK‐5F7 were 0.6 ± 0.2 and 4.6 ± 2.0 at 1 and 3 h, respectively, significantly higher (P < 0.05) than those seen for co‐injected iso‐[125I]SGMIB‐5F7 (0.1 ± 0.1 and 1.3 ± 1.2). Although the sdAbs are different, the T:
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K values obtained in this study for [18F]FN‐Tz‐TCO‐GK‐ 5F7 were considerably higher than those reported before for [18F]AlF‐NOTA‐Tz‐TCO‐GK‐2Rs15d (0.4 ± 0.1 and 2.1 ± 0.8 at 1 and 3 h, respectively; P < 0.05 at 3 h). Conclusions Although the tetrazine moiety is generally considered to be labile for standard 18F labeling conditions by SNAr, we obtained up to 47% RCY by reducing the amount of base. The sdAb 5F7 modified with a TCO moiety and a brush border enzyme‐cleavable linker was labeled with 18F via IEDDAR using [18F]2 in excellent yields with retention of affinity and immunoreactivity to HER2. This method of 18 F labeling warrants further investigation for application to sdAbs and other types of small protein constructs. ACKNOWLEDGEMENT This work was supported by National Institutes of Health Grants CA188177 and CA42324.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-320 | Imaging features and prognosis of peripheral primitive neuroectodermal tumors with 18F‐FDG PET/CT imaging Xiaobo Niu
Objective To investigate and analyze the imaging features and prognosis of peripheral primitive neuroectodermal tumors with 18F‐FDG PET/CT imaging. Methods The PET/CT imaging features of 19 patients with peripheral primitive neuroectodermal tumors confirmed by pathology from May 2012 to June 2018 were retrospectively analyzed. The maximum standardized uptake (SUVmax) and CT values of the tumors were obtained. The volume of the tumors was calculated. The disease‐ free survival time was calculated according to whether the tumors recurred, metastasized, or died. To analyze the relationship between SUVmax, tumor volume, and prognostic factors. Results Nineteen cases of pPNETs were aged from 3 to 65 years, with an average age of 21.8 years. Three cases were located in ribs and chest wall, 3 in sacrum and pelvis, 1 in left upper limb, 2 in mediastinum, 2 in lung, 1 in abdominal cavity, 1 in right nasal wing, 2 in left clavicle and supraclavicular bone, 2 in left femur, 1 in L3‐5
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vertebral body and appendix, and 1 in soft tissue mass. CT showed that the density of tumors was similar to or lower than that of adjacent muscle tissues. The CT values ranged from 20.3 HU to 50.7 HU, with an average of (38.23 + 2.11) HU. Tumor focus SUVmax (2.5‐17.2). Among them, 10 cases had osteolytic bone destruction and soft tissue mass, 3 cases had liquefied necrosis area, 2 cases had bone and periosteal reaction, 1 case had strip calcification in soft tissue mass, and 3 cases had lymph node metastasis in lung and axilla. There was no significant correlation between SUVmax and CT value (P > 0.05), and the average tumor‐free survival time of 19 patients was (47.9 + 12.8) months. Kaplan‐Meier curve analysis showed that the disease‐free survival time of patients with SUVmax 6 (X2 = 0.695, P < 0.05). COX regression analysis showed that SUVmax was an independent prognostic factor (Wald = 4.214, P < 0.05), while tumor volume was not an independent prognostic factor (Wald = 0.758, P > 0.05). Conclusion 18 F‐FDG PET/CT can complement each other in the anatomical and metabolic changes of peripheral primitive neuroectodermal tumors. Combined with semi‐quantitative analysis, it can evaluate the prognosis of patients and provide a basis for the diagnosis and treatment of peripheral primitive neuroectodermal tumors.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-321 | Synthesis of [89Zr]Zr‐DFO‐PEG5‐Tz and in vivo evaluation of bioorthogonally labeled antibody Dave Lumen1; Danielle Vugts2; Pauline Lang3; Marion Chomet4; Mariska Verlaan5; Ricardo Vos; Albert Windhorst6; Anu Airaksinen1 1
University of Helsinki, Finland; 2 Amsterdam UMC,VU University,
Netherlands; 3 Chemistry research laboratory, Department of Chemistry, University of Oxford, United Kingdom; 4 Amsterdam UMC, VU University, Radiology and Nuclear Medicine, Netherlands; 5 Amsterdam UMC, VU UniversityRadiology and Nuclear medicine, Radionuclide Center, De Boelelaan 1085c, Amsterdam, Netherlands; 6 VU University Medical Center, Netherlands
Objectives The aim of this project was to develop a tetrazine based prosthetic group to label antibodies by inverse electron‐ demand Diels–Alder reaction (IEDDA) in vivo, i.e., for
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pretargeted immuno‐PET. 89Zr has a long half‐life (78.4 h) for which reason it is increasingly used for following antibodies in vivo. Benefit of the pretargeted approach would be a reduced radioactive dose to patient because of lower blood circulation time of the radiolabeled compound and shorter lived isotopes could be used for imaging.[1] The pretargeted approach was used for 89Zr‐labelling of U36, which is an antibody targeting to human head and neck squamous cell carcinoma. Antibody U36 was chosen because it has long blood circulation time and a slow internalization rate. Methods DFO‐PEG5‐Tz was synthesized from tetrazine‐PEG5‐ amine and DFO mesylate under mild reaction conditions (RT, DMF, Et3N) and purified by using semi‐prep. HPLC and evaporated to dryness. DFO‐PEG5‐Tz was radiolabeled with 89Zr using [89Zr]Zr‐oxalate under neutral conditions. The precursor was added in 0.1 M HEPES buffer and after 30 min reaction, [89Zr]Zr‐DFO‐PEG5‐Tz was purified by a solid‐phase extraction using a Sep‐Pak light C‐18 cartridge. TCO‐conjugated U36 antibody was prepared by conjugating U36 with 40 mol. equivalents of TCO‐PEG4‐NHS in PBS (pH = 9, RT, overnight). The TCO conjugated U36 was purified with a PD‐10 and Amigon centrifuge filters. To analyze the amount of active TCOs on the antibody surface, the TCO/mAb ratio was determined by HPLC using tetrazine titration. The total amount of TCO was analyzed by using a matrix‐ assisted laser desorption/ionization mass spectrometry (MALDI). The biodistribution of [89Zr]Zr‐DFO‐PEG5‐Tz was evaluated in HNX‐OE‐SCC xenograft bearing mice. At day 1, a first group was injected with in vitro labeled [89Zr]Zr‐DFO‐PEG5‐Tz‐TCO‐U36 (4.4 ± 0.4 MBq, 100 μg) and two other groups with U36‐TCO (100 μg) only. Group 2 got [89Zr]Zr‐DFO‐PEG5‐Tz (4.1 ± 0.3 MBq, 0.7 μg) 24 h after the U36‐TCO injection and group 3 got (3.9 ± 0.5 MBq, 0.7 μg) 48 h after the U36‐TCO injection. PET imaging was performed 1 h, 24 h, 4 8, and 72 h post mAb injections and bio‐distribution was performed directly after the last PET scan. Results DFO‐PEG5‐Tz was synthesized as a pink solid with 27 ± 13% yield (n = 2). Excellent radiolabeling yields (>90%) for [89Zr]Zr‐DFO‐PEG5‐Tz were achieved when 1 μg (0.94 nmol) of DFO‐PEG5‐Tz was used. A ratio 3.28 ± 1.0 TCOs per antibody was determined by tetrazine titration, while MALDI revealed that there were actually 27 TCOs/mAb. PET imaging showed clear tumor uptake in both in vitro and in vivo labeled U36 antibodies (1.06 ± 0.2 SUV for group 1 and 1.08 ± 0.4 SUV and 0.32 ± 0.2 SUV for groups 2 and 3, 72 h post injection of mAb). The best results were obtained when [89Zr]Zr‐ DFO‐PEG5‐Tz was injected 24 h after the mAb
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(1.08 ± 0.4 SUV, 72 h post mAb injection) and even after 48 h after the mAb injection, the click reaction was still clearly seen (0.32 ± 0.2 SUV, 72 h post mAb injection). Based on the ex vivo results, the liver uptake, especially for in vitro labeled U36 antibody, was higher (14.14 ± 2.9%ID/ g) than previously reported.[2] This indicated that the TCO‐conjugation of U36 had altered its pharmacokinetics Conclusions DFO‐PEG5‐Tz was successfully synthesized and labeled with 89Zr. Biological evaluation of the [89Zr]Zr‐DFO‐ PEG5‐Tz confirmed that in vivo click reaction worked, but increased liver uptake was observed. The ex vivo/ in vivo results exhibited that pharmacokinetics of U36‐ TCO was changed and majority of radioactivity was found in liver. Our next objective is to find the optimal TCO/mAb ratio, in which pharmacokinetics of the U36 antibody remains unchanged but still containing enough TCOs available for the in vivo click reaction. ACKNOWLEDGEMENTS Funded by the Academy of Finland (298481), CHEMS and Emil Aaltosen säätiö. R EF E RE N C E 1. Selvaraj Ramajeyam, Fox Joseph M, Curr Opin Chem Biol, Volume 17, Issue 5, 2013, Pages 753‐760 2. Vugts et al., Bioconjug Chem, 2011 22 (10), 2072‐2081
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-322 | Fluorine‐18 labeling of a single domain antibody fragment with 2,5‐dioxopyrrolidin‐1‐yl 3‐(1‐(2‐(2‐(2‐(2‐[18F]fluoroethoxy)ethoxy) ethoxy)ethyl)‐1H‐1,2,3‐triazol‐4‐yl)‐5‐ (guanidinomethyl)benzoate, an alternative residualizing prosthetic agent. Zhengyuan Zhou1; Darryl McDougald2; Nick Devoogdt3; Michael Zalutsky2; Ganesan Vaidyanathan2 1
Duke University, United States; 2 Duke University Medical Center, United
States; 3 In Vivo Cellular and Molecular Imaging (ICMI), Vrije Universiteit Brussel (VUB), Belgium
Objectives Single domain antibody fragments (sdAbs) are an attractive vector for immunoPET. Earlier, we labeled anti‐ HER2 sdAbs with 18F using a residualizing prosthetic agent, N‐succinimidyl 3‐((4‐(4‐[18F]fluorobutyl)‐1H‐1,2,3‐ triazol‐1‐yl)methyl)‐5‐(guanidinomethyl)benzoate ([18F]
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SFBTMGMB or [18F]RL‐I; Figure 1A; DOI: 10.2967/ jnumed.115.171306; DOI: 10.1007/s11307‐017‐1082‐x). The prosthetic agent was synthesized by a copper‐catalyzed click reaction between an azide‐ and guanidine‐ bearing molecule with 6‐[18F]fluorohexyne (FH). However, one drawback of FH is its extreme volatility, making the synthetic manipulations difficult. To overcome this problem, we developed an analogous agent by reversing the click partners—the guanidine‐bearing molecule contained the alkyne moiety, which was clicked with a fluoroalkyl azide that included a PEG linker. Methods N‐succinimidyl 3‐((2,3‐bis (tert‐butoxycarbonyl) guanidino)methyl)‐5‐ethynylbenzoate (4; Figure 1B) was synthesized in three steps from 2‐(trimethylsilyl)ethyl 3‐ (hydroxymethyl)‐5‐iodobenzoate (1; https://doi.org/ 10.1016/j.nucmedbio.2014.07.005). It was clicked with 1‐ azido‐2‐(2‐(2‐(2‐[18F]fluoroethoxy)ethoxy)ethoxy)ethane (DOI: 10.1021/jm101110w) and the Boc groups from the resulting intermediate 5 removed to obtain 2,5‐ dioxopyrrolidin‐1‐yl 3‐(1‐(2‐(2‐(2‐(2‐[18F]fluoroethoxy)ethoxy)ethoxy)ethyl)‐1H‐1,2,3‐triazol‐4‐yl)‐5‐(guanidinomethyl) benzoate (6; [18F]SFETGMB; [18F]RL‐III; Figure 1B). An anti‐HER2 sdAb 2Rs15d was labeled with 18F and 125I by conjugating it with [18F]RL‐III and N‐succinimidyl 4‐ ([125I]SGMIB; guanidinomethyl‐3‐[125I]iodobenzoate doi:10.1038/nprot.2007.20), respectively. The purity of [18F] RL‐III‐2Rs15d was evaluated by TCA precipitation, SDS PAGE, and size‐exclusion HPLC. Its HER2‐binding affinity was determined in a saturation binding assay using HER2‐ expressing BT474M1 human breast carcinoma cells and its immunoreactive fraction (IRF) assessed by the Lindmo method. Paired‐label internalization of [18F]RL‐III‐2Rs15d and [125I]SGMIB‐2Rs15d was performed on BT474M1 cells in vitro. The biodistribution of [18F]RL‐III‐2Rs15d and [125I] SGMIB‐2Rs15d were compared in athymic mice bearing subcutaneous HER2‐expressing SKOV3 human ovarian carcinoma xenografts. Results Boc2‐[18F]SFETGMB was synthesized in an overall radiochemical yield of 22.1 ± 2.4% (n = 5) in 125 min. [18F]RL‐ III was conjugated to 2Rs15d (2 mg/mL) in 37.5 ± 13.5% yield. The radiochemical purity of [18F]RL‐III‐2Rs15d was >96%. Kd and IRF were 5.7 ± 0.3 nM and 81.5 ± 1.0%, respectively. The percent of initially bound radioactivity from [18F]RL‐III‐2Rs15d that internalized in BT474M1 cells was 10.8 ± 1.0%, 10.6 ± 0.4%, and 9.8 ± 0.7%, respectively, at 1, 2, and 4 h; the corresponding values for [125I]SGMIB‐ 2Rs15d were 10.2 ± 0.6%, 10.0 ± 0.4%, and 9.1 ± 0.4%. Uptake in SKOV3 xenografts for [18F]RL‐III‐2Rs15d was 4.0 ± 0.5%ID/g, 4.2 ± 1.4%ID/g, and 2.5 ± 0.3%ID/g, at 1, 2, and 3 h, respectively. These values for [125I]SGMIB‐ 2Rs15d were 5.5 ± 0.8%ID/g, 6.4 ± 3.1%ID/g, and
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3.8 ± 0.7%ID/g (P < 0.05 except at 2 h). Uptake in a some normal tissues was considerably higher for [18F]RL‐III‐ 2Rs15d compared with [125I]SGMIB‐2Rs15d (kidney 2‐4‐ fold; liver 25‐43‐fold; spleen 14‐19‐fold). Conclusions The prosthetic agent [18F]RL‐III was synthesized in about 3‐fold higher radiochemical yields than that obtained
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earlier for [18F]RL‐I. The sdAb 2Rs15d was labeled with [18F]RL‐III in similar yields as obtained for [18F]RL‐I giving considerable advantage with respect to RCY for [18F]RL‐III‐ 2Rs15d. Tumor uptake both in vitro and in vivo of [18F]RL‐ III‐2Rs15d was similar to that for co‐incubated/injected [125I]SGMIB‐2Rs15d demonstrating the residualizing ability of [18F]RL‐III. Normal tissue uptake of [18F]RL‐III‐
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2Rs15d was similar to that seen earlier for [18F]RL‐I‐2Rs15d albeit in a different model. These results suggest that [18F] RL‐III is a better prosthetic agent than [18F]RL‐I and warrants further investigation with further structural modifications to reduce uptake of activity from labeled sdAbs in some normal tissues. ACKNOWLEDGEMENT This work was supported by National Institutes of Health Grants CA188177 and CA42324.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-323 | The value of 18F‐FDG PET/CT in the diagnosis of multiple myeloma Xiaobo Niu
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Objective To retrospectively study the application value of 18F‐FDG PET/CT in multiple myeloma. Methods From January 2011 to March 2014, 43 patients with clinically suspected multiple myeloma were selected, including 24 males and 19 females, aged 38‐74 years, with an average age of (49.7 + 0.6) years. All patients underwent PET/CT examination, which was confirmed by bone marrow puncture or pathological biopsy. The results of PET/ CT and pathology were compared and analyzed. The sensitivity, specificity, and accuracy were calculated to evaluate the diagnostic efficacy. Results Of 43 patients, 23 were diagnosed by PET/CT, and 24 by bone marrow biopsy or biopsy. Among them, 20 were diagnosed by PET/CT, 3 were false positive and 4 were false negative. The diagnostic sensitivity, specificity, accuracy and positive predictive value of PET/CT was 83.3%
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(20/24), 80% (16/20), 83.7% (36/43), respectively. 86.9% (20/23) and 80% (16/20) were negative predictors. Of the 24 patients with pathologically confirmed MM, 291 positive lesions were detected in 20 patients with matched PET/CT. Among them, 261 (89.7%) showed metabolic increase in PET, with an average SUVmax of 3.3 + 0.81 (range 2.9‐12.7). 238 (81.8%) showed osteolytic bone destruction on CT. In 20 patients, the results of PET/CT coincided with pathological diagnosis. In the same machine, CT showed mostly erosion, soap bubble, and penetrating bone destruction, while PET showed increased uptake of 18F‐FDG. Conclusion 18 F‐FDG PET/CT is of great value in the diagnosis of multiple myeloma and in judging the extent of lesions.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-324 | Carbon‐11 labeled BLZ945 as PET tracer for Colony Stimulating Factor 1 Receptor imaging in the brain Berend van der Wildt; Zheng Miao; Jun Hyung Park; Samantha Reyes; Jessica Klockow; Bin Shen; Frederick Chin Stanford University, United States
Introduction Glioblastoma multiforme (GBM) is a devastating disease that has very limited treatment options and concomitant extremely poor prognosis.1 Novel inhibitors like BLZ945 are targeting Colony Stimulating Factor 1 Receptor (CSF‐ 1R) on tumor‐associated macrophages and microglia (TAMs)2, which together can account for half of the total cells in the tumor mass.3 By inhibiting this receptor, TAMs in the tumor microenvironment are either depleted or reprogrammed from a tumor supportive to a tumor
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suppressing phenotype.2 The aim of the current study is to develop a BLZ945 derived radiotracer for PET imaging of CSF‐1R expression in the brain as potential future companion diagnostic for CSF‐1R targeting therapies. Methods BLZ945 and a designed derivative were evaluated for inhibitory potency against CSF‐1R and related kinases PDGFR‐β and c‐KIT. BLZ945 was radiolabeled and evaluated in vivo by PET scanning in healthy Nu/Nu mice (n = 4 per group). Brain uptake and blood clearance (as determined by heart uptake) were evaluated both at baseline and during efflux transporter blockade (cyclosporine A, 30 mg/kg, i.v., 30 minutes prior to tracer injection). Finally, a displacement PET experiment was performed, where mice were treated with BLZ945 (1 mg/kg, i.v.) at 30 minutes post tracer administration. Results BLZ945 was the most potent compound in our series with an IC50 value of 7.0 ± 0.6 nM. Radiolabeling of this compound was achieved by methylation of the corresponding des‐methyl precursor in DMF at 90oC for 5 minutes, using Bu4NOH as a base. After formulation, [11C]BLZ945 was obtained in 3% decay corrected yield in a 40 minute synthesis procedure. The major side‐ product was the result of N‐methylation at the aminobenzothiazole group. Brain uptake of [11C] BLZ945 was moderate, and increased by about 2.5‐fold after Cyclosporin A treatment. Brain radioactivity could not be displaced, hinting at high non‐specific radiotracer uptake. A brain radiometabolite analysis will be performed to confirm the non‐specific binding of BLZ945 in the brain. Other future work will focus on structurally distinct inhibitors towards PET imaging of CSF‐1R on macrophages and microglia in the brain. Conclusion and discussion [11C]BLZ945 was successfully synthesized in a one‐step methylation reaction, but seems unsuitable as a PET tracer for imaging of CSF‐1R expression in the brain due to its high efflux substrate characteristics and high non‐specific binding.
Figure 1: A) Structure of BLZ945 and fluoroethyltriazole derivative and B) time‐activity curves of [11C]BLZ945 following administration to Nu/Nu mice at various experimental conditions.
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R EF E RE N C E S 1. Johnson DR et al. J Neurooncol, 2012 107, 359‐64. 2. Pyonteck SM. et al. Nat Med, 2013.19, 1264‐1272. 3. Charles NA et al. Glia, 2012, 60, 502‐514.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-325 | A zirconium‐89 labeled star‐PEG polymer as a radiotracer for image‐guide drug delivery Denis Beckford‐Vera1; Shaun Fontaine2; Guillaume Trusz1; Tony Huynh1; Joseph Blecha1; Gary Ashley3; Daniel Santi3; Henry VanBrocklin1 1
University of California, San Francisco, United States; 2 ProLynx LLC,
United States; 3 ProLynx LCC, United States
Objectives Nanomedicines are playing an increasing role in delivery of cancer therapeutics.1 However, variability in treatment response significantly limits their effectiveness and clinical translation. 2 The delivery and accumulation of these nanomedicines to solid tumors are largely driven by the enhanced permeability and retention (EPR) effect. 3 EPR is a heterogeneous phenomenon that is affected by several variables including vessel density, hypoxia, and interstitial fluid pressure.4 EPR may vary from patient to patient and even within patients at different tumor sites.5 This supports the need for image‐guided drug delivery methods to provide an in vivo assessment of EPR of nanomedicines before they are administered to patients. Molecular imaging, using Positron Emission Tomography (PET), provides a means to non‐invasively visualize delivery and quantitate accumulation of therapeutic agents, thereby correlation between delivery and patient outcome. This may directly influence the nanomedicine field by overcoming the challenge of choosing the right patients in clinical trial settings. PLX‐038 (ProLynx LLC) is a conjugate of 4 arm star‐PEG (40 kDa) with 4 equivalents of SN‐38 that has showed potential in a clinical trial. SN‐38 is the active metabolite of the widely used chemotherapeutic Irinotecan. The aim of this work was to develop and evaluate the potential of a companion PET imaging probe as an EPR marker for the therapeutic version (PLX‐038). Methods Three DFO‐star‐PEG conjugates, synthesized at ProLynx, (Figure 1A) were radiolabeled with Zr‐89 and characterized following procedures previously described with
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minor modifications.6 The pharmacokinetics properties of the star‐PEG conjugates were evaluated in four different tumor models: cell derived human breast cancer MX‐1, cell derived human colorectal carcinoma HT‐29, pancreatic adenocarcinoma patient derived xenograft (PDX) tumor, and a model of breast cancer metastasis MDA‐MB‐231. The model of metastatic breast cancer was developed by intracardiac injection of MDA‐MB‐231 cells and confirmed by bioluminescence imaging. Tumor bearing mice (n = 4‐5) were injected with 150–200 μCi (~7 nmol) of Zr‐89 labeled star‐PEG conjugates. Serial μPET/CT scans were taken at 1, 24, 48, 72, 96, and 216 hours post‐injection. For the metastatic breast cancer model, an 18 F‐FDG scan was also taken 24 h prior administration of 89 Zr‐star‐PEG. Tumor and healthy tissue accumulation of the tracer were determined from the mouse μPET/CT images. After the last imaging time‐point, mice were euthanized, and tumor, blood, and organs were weighted and counted. Results from the ex‐vivo biodistribution and the imaging studies were compared. Results Radiochemical yield, calculated from the initial 89Zr‐Oxalate activity, was always >85%, and radiochemical purity was higher than 98%. In all tumor models studied, 89Zr‐ DFO‐star‐PEG conjugates cleared from the bloodstream and concentrated within the tumor with little to no accumulation within the major organs (Figure 1B). Tumor maximum uptake range from 5.81–18.14%ID/mL and occurred between the 72 and 96 hour time points. Tumor uptake had higher variability in pancreatic adenocarcinoma PDX model compared to that observed in xenografts models. Breast cancer metastasis was clearly visualized using 89Zr‐star‐PEG 6d post‐injection while 18 F‐FDG scan did not show any uptake in the breast cancer metastasis (Figure 1C). Conclusions All 89Zr‐star‐PEG conjugates showed similar pharmacokinetics patterns, demonstrating equivalence between the three star‐PEG conjugates. Therefore, the89Zr‐DFO‐star‐ PEG could be a radiotracer for PLX‐038. The variability observed in 89Zr‐DFO‐star‐PEG tumor uptake within the PDX tumor model could be related to the heterogeneity of PDX animal models. Here, we also demonstrated that metastatic tumors also exhibit EPR and it can be detected by PET. ACKNOWLEDGEMENTS UCSF Radiology seed grant (DBV) RE FER EN CES 1. Ventola, C. L P&T2017; 42:742–755. 2. Miller, M. A. et al. Sci Transl Med2015: 7(314): 314ra183. 3. Maeda, H. Adv Drug Deliv Rev 2015; 91:3–6.
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4. Golombek, S. K. et al. Adv Drug Deliv Rev2018; 130:17–38. 5. Bertrand, N. et al. Adv Drug Deliv Rev2014; 66:2–25. 6. Vosjan, M. J. W. D. et al. Nat Protoc 2010;5:739–743.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-326 | ImmunoPET imaging of CD146 for orthotopic breast cancer detection Lei Kang1; Dawei Jiang2; Dalong Ni; Wei3; Engle4; Wang1; Weibo Cai2 1
Peking University First Hospital, China; 2 University of Wisconsin‐
Madison, United States; 3 Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China; 4 Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, United States
Purpose CD146 has been found o overexpress in various malignant tumors and thus is considered as a cancer biomarker. In this study, we used a 64Cu‐labeled CD146‐
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specific antibody and evaluated its use for quantitative immunoPET imaging of CD146 expression in breast cancer orthotopic models. Methods After the anti‐CD146 antibody (YY146) was conjugated to 1,4,7‐triazacyclononane‐triacetic acid (NOTA), it was radiolabeled with 64Cu. CD146 expression was evaluated in three human breast cancer cell lines (MB‐231, MB‐ 435, and MCF‐7) by flow cytometry and western blot. The biodistribution and tumor uptake of 64Cu‐NOTA‐ YY146 was assessed by serial PET imaging in orthotopic breast tumor‐bearing mice within 48 h. The tumor uptake of 64Cu‐NOTA‐YY146 was evaluated by drawing region of interest at different time points. Biodistribution and immunohistochemistry studies were performed for validation. Results Flow cytometry and western blot studies showed similar results that the MB‐435 cell line had a high level of expression of CD146. The MB‐231 cell line had a moderate level while MCF‐7 had a low level of expression of CD146. In the imaging, MB‐435 orthotopic tumors could be visualized clearly after the injection of 64Cu‐
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NOTA‐YY146. The showed uptake of 64Cu‐NOTA‐ YY146 was peaking at 16.5 ± 2.8%ID/g while it was low in the MCF‐7 model (3.6 ± 1.2%ID/g) at 48 h after injection; n = 4. Ex vivo biodistribution validated the results of PET imaging. Histological stain showed a similar trend of the expression of CD146 with PET imaging
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in MB‐435 and MCF‐7 tumors. Conclusion The tumor uptake of 64Cu‐NOTA‐YY146 shows a similar trend of CD146 expression in breast cancer orthotopic models. 64 Cu‐NOTA‐YY146 can be potentially used for imaging breast cancer and evaluating the CD146 expression in vivo for the monitoring therapeutic response.
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Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-327 | Imaging hypoxia‐driven regulation of nucleoside and amino acid transporters in breast cancer Daniel Krys1; Frank Wuest2; Melinda Wuest2; Stephanie Mattingly3; Ingrit Hamann2 1
University of Alberta/Department of Oncology, Canada; 2 University of
Alberta, Canada; 3 Department of Oncology, University of Alberta, Canada
Objectives Reduced oxygen supply in tumors leads to tumor hypoxia, activates HIF‐1α, which then controls the expression of multiple target genes including membrane transporters with strong dominance of GLUT1. In this study, we explore function of nucleoside transporters (hENT) and amino acid transporters (Xc‐, LAT1) in breast cancer under normoxic and hypoxic conditions. Methods We studied protein levels and functionality of nucleoside transporter hENT1, and amino acid transporters LAT1 and xc‐ under normoxic and hypoxic conditions using Western Blot experiments. Cellular uptake experiments were carried out with [18F]FLT to assess hENT1, [18F] FDOPA for LAT1, and [18F]FPSG for Xc‐in estrogen receptor positive (ER(+)) MCF7 and MDA‐MB231 triple‐negative breast cancer (TNBC) cells. Expression and function of transporters in vivo were studied with dynamic PET imaging in tumor‐bearing mice using radiotracers [18F]FLT, [18F]FDOPA and [18F]FPSG. Results Increased [18F]FLT uptake was observed in MDA‐MB231 cells (241 ± 10% radioactivity/mg protein) compared to ER(+) MCF7 cells (147 ± 18% radioactivity/mg protein) at 60 min. This corresponded with higher hENT1 protein
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levels in MDA‐MB231 versus MCF7 cells. Data also indicated that [18F]FLT uptake and hENT1 levels were not influenced significantly by hypoxia. LAT1 expression was higher in ER(+) MCF7 versus MDA‐MB231 cells. Cellular uptake of [18F]FDOPA revealed higher uptake in ER(+) MCF7 cells (467 ± 98% radioactivity/mg protein) compared to TNBC MDA‐MB231 cells (105 ± 54% radioactivity/mg protein) under normoxic conditions at 30 min. Xc‐ protein levels were comparable in both cell lines. Cellular uptake studies with [18F]FPSG showed increased uptake in MDA‐MB231 cells (127 ± 66% radioactivity/mg protein) compared to MCF7 cells (9.83 ± 1.4% radioactivity/mg protein) at 60 min. [18F]FLT‐PET revealed comparable uptake of the radiotracer in MCF‐7 and MDA‐MB231 tumors. Uptake of [18F]FDOPA in MCF‐7 tumors was higher compared with MDA‐MB231 tumors. The situation was reversed in the case of [18F] FPSG, where radiotracer uptake was higher in MDA‐ MB231 tumors compared to MCF‐7 tumors (Figure 1). (Image/Figure Upload) Figure 1. Representative PET images of [18F]FLT, [18F]FPSG and [18F]FDOPA in MDA‐MB231 and MCF7 tumor‐bearing mice. Conclusions Overall, there is increased transport of radiotracers [18F] FLT and [18F]FPSG in MDA‐MB231 breast cancer cells, while uptake of radiotracer [18F]FDOPA is increased in MCF7 cells. We only observed minimal hypoxic regulation of studied nucleoside (hENT1) and amino acid (LAT1 and Xc‐) transporters in both cell lines. The experiments will help to validate radiotracers [18F]FLT, [18F] FDOPA and [18F]FSPG as alternative and complementary imaging agents to widely used [18F]FDG‐PET in breast cancer. ACKNOWLEDGEMENTS The authors gratefully acknowledge the Dianne and Irving Kipnes Foundation, the Alberta Cancer Foundation, the Faculty of Medicine and Dentistry of the University of Alberta, and the Government of Alberta, Student Aid Program.
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Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-328 | Mild and site‐specific labeling of peptides using a novel biarsenical imaging probe Mikhail Kondrashov1; Samuel Svensson2; Peter Strom3; Christer Halldin4; Magnus Schou5 1
Karolinska Institute, Sweden; 2 BioPercept AB, Sweden; Linköping
University, Sweden; 3 Novandi Chemistry AB, Sweden; 4 Karolinska Institutet, Sweden; 5 AstraZeneca PET Centre at Karolinska Institutet, Sweden
Objectives FlAsH‐EDT2 is a membrane permeable organoarsenic compound widely used to visualize proteins in living cells by fluorescence microscopy.1 Its binding relies on the interaction between the biarsenic motif and a peptide sequence that needs to be installed in the target protein (Cys‐Cys‐Pro‐Gly‐Cys‐Cys). Importantly, this sequence is rare in naturally occurring proteins and thus ensures high site‐specificity in the labeling. On the basis of its many attractive features, we hypothesized that suitable analogs of FlAsH‐EDT2 could provide valuable agents for in vivo protein imaging using positron emission tomography (PET). Radtag (1), a biarsenic compound bearing the OH‐group available for
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substitution was proposed as a starting material for modification. Methods A PETtrace cyclotron (GEMS, Uppsala, Sweden) was used to produce [11C]methane and [18F]fluoride that were further converted to [11C]methyl triflate and [18F] fluoroethyl triflate according to published procedures. The radiolabeling agents were subsequently reacted with the corresponding phenolic precursor and potassium carbonate in a solution of acetone (11C) or acetonitrile (18F). Radiochemical purities (RCP) were determined using radio‐HPLC. Presented radiochemical yields are not decay‐corrected. Two peptides were investigated in this study; the melanocyte stimulating hormone peptide analogue NAPamide (MSH‐NAP) and the PD‐L1IgV targeting peptide (D1). Animal imaging was performed on the nanoScan (Mediso, Budapest, Hungary) PET system. Results Crude 11C‐Radtag derivative was obtained in >95% RCP after a 2 min reaction at rt. [11C]2 was isolated in 4% RCY (not corrected for decay), at a RCP >90% and at a specific radioactivity >74 GBq/μmol. A solution of 11C‐ Radtag in phosphate buffered saline containing ethanol (5%) and sodium ascorbate was next reacted with the MSH‐CCPGCC‐NDP peptide (~0.1 mg) at room temperature during 10 min to produce the target peptide in >90% RCP. Alternatively, crude [11C]2 was coupled with the CCPGCC‐NAPamide peptide (4.5 mg) producing [11C] CCPGCC‐NAPamide 4 after HPLC purification.
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Following injection of labeled peptide into melanoma bearing mice (B16/F10 cell line), Compound 4 accumulated in tumor tissue (1.6 ratio to muscle at 60 min). A375 cell line, which contains less target MC1R receptors, was used as a negative control and no accumulation in the tumor tissue was observed. Crude 18F‐Radtag derivative 3 was obtained in >90% RCP after a 5 min reaction at 80°C, then separated from the phenolic precursor by passing through a short silica cartridge, which was eluted with Et2O:Et3N:CH3CN (20:1:1) mixture to afford [18F]3 in a 70% isolated RCY (based on produced [18F]fluoroethyl triflate). Following evaporation of solvents, a 10 min reaction with CCPGCC‐D1 peptide in aqueous buffer solution afforded the 18F‐labelled peptide (5) in ~50% RCP. After the HPLC purification, [18F]5 was isolated in 10% RCY and at RCP > 95%. Conclusion These preliminary data demonstrate the potential of radiolabeled FlAsH‐EDT2 analogs as site‐specific peptide labeling agents. The peptides do not require any linker groups, but rather the inclusion of a set of six natural amino acids. Their synthesis was performed using conventional automated solid phase synthesis apparatus. The unique regioselectivity of the diarsenic motif is promising for direct bioorthogonal in vivo labeling for PET. R EF E RE N C E S 1. Griffin, B.A., Adams, S.R., Jones, J., and Tsien, R.Y. Methods Enzymol, 2001, 327, 565‐578.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-329 | Development of a 89Zr‐labelled anti‐ EGFR and cMET bispecific antibody for PET imaging of triple‐negative breast cancer Sun Suxia1; Alessandra Cavaliere2; Supum Lee3; Sheri Moores4; Yiyun Huang5; Bernadette Marquez‐Nostra1 1
Yale University, United States; 2 Department of Radiology and
Biomedical Imaging, Yale University, United States; 3 Yale School of Medicine, United States; 4 Janssen Pharmaceutical Philadelphia, PA, United States; 5 PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States
Objectives Triple negative breast cancer (TNBC) represent 15‐20% of breast cancer cases (1). The epidermal growth factor receptor (EGFR) and the hepatocyte growth factor
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receptor (HGFR or c‐MET) are two tyrosine kinase receptors overexpressed in the basal‐like subtype of TNBC and are associated with cancer cell proliferation and metastasis (2‐3). Recently, a novel bispecific antibody (bsAb) has been developed to target both EGFR and c‐MET for lung tumors (4) showing greater downstream inhibition of both signaling pathways in vitro and in vivo than single pathway of either EGFR or c‐ MET. The purpose of this study is to develop a companion diagnostic bsAb PET imaging tracer targeting EGFR and c‐MET and to validate EGFR and c‐MET expression in preclinical models of TNBC. The ultimate goal is to predict response to anti‐EGFR and anti‐cMET therapy using PET imaging. Methods [89Zr]ZrDFO‐bsAb PET tracer was synthesized via conjugation of desferrioxamine‐p‐benzyl‐isothiocyanate metal chelate (DFO‐Bz‐NCS) to the bsAb (5) followed by radiolabelling with [89Zr]Zr‐Oxalate. Validation of EGFR and c‐MET expression in selected TNBC cell lines (in vitro) was performed by western blotting and by cellular uptake studies. Validation of EGFR and c‐MET expression in cell‐derived xenografts models tumor tissue (ex vivo) was performed via immunohistochemical staining. The lung cancer cell line HCC827 was used as positive control (4). Results [89Zr]ZrDFO‐bsAb was synthesized with a radiochemical yield of ≥98% as determined by radio‐TLC. Protein aggregation evaluation was performed via size‐exclusion chromatography and showed ≥96% monomeric protein. Western blots confirmed moderate expression of c‐ MET and high expression of EGFR in MDA‐MB‐468 cell line. Moderate expression of c‐MET and EGFR was found in MDA‐MB‐231 cell line. MDA‐MB‐453 cell line was confirmed to have moderate expression of c‐MET and low expression of EGFR. Cellular uptake studies with [89Zr]ZrDFO‐bsAb confirmed the results from the western blot (MDA‐MB‐468, MDA‐MB‐231, and MDA‐ MB‐453 showed uptake of 68%, 23%, and 2.7%, respectively). We further evaluated the protein expression of EGFR and c‐MET in cell‐derived xenografts models tumor tissue via immunohistochemical staining. MDA‐ MB‐468 and MDA‐MB‐231 cell lines were confirmed to have high expression of c‐MET and EGFR (H‐ score = +200). MDA‐MB‐453 instead showed negative expression of both proteins (H‐score = +5). Conclusions A 89Zr‐labelled bsAb targeting both EGFR and c‐MET has been optimized. Validation of EGFR and c‐MET expression was performed in selected breast cancer cell lines (in vitro) and in cell‐derived xenografts models tumor tissue (ex vivo). Small‐animal PET
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imaging of [89Zr]ZrDFO‐bsAb and therapy studies with bsAb in cell‐derived xenograft models are currently ongoing. ACKNOWLEDGMENTS We thank the Yale Pathology Translational Services for the immunohistochemical analyses; Yale PET Center; and Yale Cancer Center Lion Heart pilot fund. R EF E RE N C E S 1. Bauer KR, Brown M, Cress RD, Parise CA, Caggiano V. Descriptive analysis of estrogen receptor (ER)‐negative, progesterone receptor (PR)‐negative, and HER2‐negative invasive breast cancer, the so‐called triple‐negative phenotype: a population‐based study from the California cancer Registry. Cancer 2007;109:1721‐1728. 2. Corkery B, Crown J, Clynes M, O'Donovan N. Epidermal growth factor receptor as a potential therapeutic target in triple‐negative breast cancer. Ann Oncol 2009;20:862‐867. 3. Zagouri F, Bago‐Horvath Z, Rossler F, et al. High MET expression is an adverse prognostic factor in patients with triple‐negative breast cancer. Br J Cancer 2013;108:1100‐1105. 4. Moores SL, Chiu ML, Bushey BS, et al. A Novel Bispecific Antibody Targeting EGFR and cMet Is Effective against EGFR Inhibitor‐Resistant Lung Tumors. Cancer Res 2016;76: 3942‐3953. 5. Marquez‐Nostra BV, Lee S, Laforest R, et al. Preclinical PET imaging of glycoprotein non‐metastatic melanoma B in triple negative breast cancer: feasibility of an antibody‐based companion diagnostic agent. Oncotarget 2017;8:104303‐104314.
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Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-330 | [18F]Triacoxib: A novel radiotracer for PET imaging of COX‐2 identified through in situ click chemistry. Marcus Litchfield; Melinda Wuest; Darryl Glubrecht; Todd McMullen; David Brindley; Frank Wuest University of Alberta, Canada
Objectives Cyclooxygenase‐2 (COX‐2) enzyme is significantly upregulated under acute and chronic inflammatory conditions, including cancer, wherein it promotes angiogenesis, tissue invasion, and resistance to apoptosis. Due to the high expression of COX‐2 in various cancers, COX‐2 has become an important target for molecular imaging and therapy of cancer. Recently, our group applied in situ click chemistry for the development of highly potent and selective COX‐2 inhibitor triacoxib [1]. Herein, we describe the radiosynthesis and validation of [18F] triacoxib, a novel radiotracer for PET imaging of COX‐2. Methods Synthesis of [18F]triacoxib was accomplished using Cu‐mediated late‐stage radiofluorination chemistry. Cellular uptake
Figure 1. Radiosynthesis (left), PET imaging (right, top) and autoradiography/COX‐2 IHC (right, bottom) of [18F] triacoxib
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and inhibition studies with [18F]triacoxib were carried out in HCA‐7 cells. Concentration dependent inhibition of [18F] triacoxib uptake was performed with celecoxib, rofecoxib, pyricoxib, and triacoxib. [18F]Triacoxib was further evaluated in HCA‐7 tumour‐bearing NIH (III) mice using dynamic PET imaging, radiometabolite analysis, autoradiography, and COX‐2 immunohistochemistry (IHC). In vivo blocking studies were carried out by i.p. injection of 2 mg of celecoxib 60 min prior to radiotracer administration. Results Radiosynthesis, including radio‐HPLC purification, of [18F] triacoxib was accomplished within 140 min in decay‐ corrected radiochemical yields of 30% (n = 23) at molar activity (Am) >40 GBq/mmol. Cellular uptake of [18F] triacoxib in HCA‐7 cells was 62.5% radioactivity/mg protein after 60 min. Cellular uptake could be reduced by 40% upon pre‐treatment with 0.1 mM celecoxib. Lipophilicity was determined by shake‐flask method (logP = 1.77), and 90% of the radiotracer remained intact after 60 min p.i.. PET imaging revealed favorable baseline radiotracer uptake in HCA‐7 tumors (SUV60min = 0.76 ± 0.02 (n = 4), which could be reduced by 20% through pre‐treatment with 2 mg of celecoxib. Blocking was further confirmed by autoradiography and COX‐2 IHC experiments (Figure 1). Conclusions [18F]Triacoxib, whose non‐radioactive analog was identified through in situ click chemistry, is a suitable radiotracer for PET imaging of COX‐2 in cancer. ACKNOWLEDGEMENTS The authors gratefully acknowledge the Dianne and Irving Kipnes Foundation, the Alberta Cancer Foundation, and the University of Alberta Faculty of Medicine and Dentistry for supporting this work. R EF E RE N C E S 1. Bhardwaj et al. Nat Commun 2017, 8, 1.
Figure 1. Radiosynthesis (left), PET imaging (right, top) and autoradiography/COX‐2 IHC (right, bottom) of [18F]triacoxib
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-331 | Development of FOXM1 inhibitors as potential theranostic agents: initial steps in the validation of FOXM1 as a positron emission tomography (PET) probe for triple negative‐ breast cancer detection. David Perez; Seyed Tabatabaei Dakhili; Cody Bergman; Jennifer Dufour; Melinda Wuest; Frank Wuest; Carlos Velazquez‐Martinez
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University of Alberta, Canada
Objectives The FOXM1 transcription factor controls the expression of essential genes related to cell cycle progression and cell replication; under normal physiological conditions, its expression is significantly decreased in terminally differentiated cells, but it is abnormally activated in most (if not all) malignant cells.1,2 During the last three years, our research group has worked on the development of novel (still experimental) FOXM1 inhibitors. We hypothesize that binding interactions exerted by FOXM1 inhibitors could not only inhibit its transcriptional activity but also serve as PET‐based imaging probes for cancer detection, specifically, 18F‐based imaging. With this purpose, we prepared derivatives from FDI‐6,3 (a still experimental and standard FOXM1 inhibitor), and selected the compound AF‐FDI to perform the radiolabeling with a F‐18 (Figure 1A). Methods We adapted the methodology reported for the synthesis of FDI‐63,4 and prepared some derivatives, which were evaluated as direct FOXM1 inhibitors using the cell free assay known as electrophoretic mobility shift assay (EMSA).3 To determine their ability to exert in vitro inhibition of the expression levels of FOXM1, we used the triple negative breast cancer cell line (MDA‐MB‐231) and the western blot protocol (given that FOXM1 controls its own expression). To measure their anti‐proliferative activity, we used the MTT assay.3 We selected derivative AF‐FDI as the most active FOXM1 inhibitor and designed a suitable radiolabeling route to add fluorine‐18 and prepared 18F‐AF‐FDI (radioactive analogue). The yet preliminary radiopharmacological evaluation of 18F‐AF‐FDI involved cell uptake and internalization experiments using MDA‐MB‐231 cells. Results EMSA results showed that AF‐FDI was able to dissociate the FOXM1‐DNA complex with an IC50 = 46.4 ± 1.19 mM and Ki = 22.2 ± 0.56 mM, and also exerted significant time‐dependent in vitro inhibition of FOXM1 expression levels in nuclear cell fractions at 40 mM, reaching an 55% inhibition at 12 h treatment. The MTT results showed that FOXM1 inhibition exerted by AF‐FDI, was also correlated with an anti‐proliferative activity, showing an IC50 = 41.91 ± 1.20 mM, at 72 h. We prepared 18F‐AF‐FDI in 60% radiochemical yield. The cell uptake results for 18F‐ AF ‐FDI, showed that it reached an overall 500% of radioactivity/mg of cell protein at 2 h (Figure 1B), and based on the internalization experiments, we found that around 55% of the radioactivity/mg of protein was internalized in cells, and 45% was membrane bound (Figure 1C). Figure 1. A) Chemical structures of FDI‐6 and AF‐FDI. B) Cell uptake
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Department of Oncology, University of Alberta, Canada; 2 University of
Alberta, Canada; 3 Department of Radiology, Albert Einstein College of Medicine, United States; 4 Department of Oncology, Division of Oncological ImagingUniversity of Alberta, Edmonton, Canada
values for 18F‐AF‐FDI. C) Membrane bound and internalized values for 18F‐AF‐FDI. Conclusions We have established the initial steps to validate FOXM1 as potential probe for PET imaging. In summary, we submit a set of preliminary results suggesting that it might be possible to use transcription factors to develop dual acting therapy/diagnostic (theranostic agents). To completely validate our hypothesis, we will conduct xenograft animal models to establish if FOXM1 may be a suitable radiotracer target for breast cancer PET imaging. ACKNOWLEDGEMENTS D.J.P is grateful with the National Council for Science and Technology (México) for the postdoctoral fellowship (287012) granted. R EF E RE N C E S 1. Koo, C.‐Y.; Muir, K. W.; Lam, E. W. F., Biochim Biophys Acta, Gene Regul. Mech. 2012, 1819, 28‐37. 2. Nandi, D.; Cheema, P. S.; Jaiswal, N.; Nag, A., Semin Cancer Biol 2018, 52, 74‐84. 3. Gormally, M. V.; Dexheimer, T. S.; Marsico, G.; Sanders, D. A.; Lowe, C.; Matak‐Vinković, D.; Michael, S.; Jadhav, A.; Rai, G.; Maloney, D. J.; Simeonov, A.; Balasubramanian, S., Nat Commun 2014, 5, 5165. 4. Kawazoe, Y.; Shimogawa, H.; Sato, A.; Uesugi, M., Angew Chem Int Ed 2011, 50, 5478‐5481.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-332 | Synthesis and in vivo evaluation of metabolic radiotracers (S) and (R) 4‐[18F] fluoro‐3‐hydroxybutyrate Stephanie Mattingly1; Melinda Wuest2; Eugene Fine3; Ralf Schirrmacher4; Frank Wuest2
Objectives The enantiomeric pair of isomers described by 3‐ hydroxybutyrate represent human metabolites that serve distinct biochemical roles. D(‐)‐3‐hydroxybutyrate is the principal circulating metabolite of hepatic fatty acid catabolism. L(+)‐3‐hydroxybutyrate is theorized to be produced by heart cells and shunted into lipid and sterol synthesis pathways of the nervous system.1,2 We have recently developed a synthetic method for the preparation of (S) and (R) 4‐[18F]fluoro‐3‐hydroxybutyrate intended as radiolabeled analogues of the endogenous D(‐) and L(+) 3‐hydroxybutyrates, respectively. Assuming metabolic similarity to their endogenous counterparts, (S)‐4‐ [18F]fluoro‐3‐hydroxybutyrate may be applicable to imaging of disorders involving changes to energy substrate utilization (cancer, Alzheimer's, cardiovascular disease, diabetes), and (R)‐4‐[18F]fluoro‐3‐hydroxybutyrate may be useful for imaging of the heart and nervous system, regions that are challenging to image with FDG due to high background uptake. Methods 4‐[18F]fluoro‐3‐hydroxybutyrate, as either enantiomer, was synthesized in three steps (2 pots) from commercially available chiral precursor (2R)‐(−)‐ or (2S)‐(+)‐glycidyl tosylate. The resulting chiral epifluorohydrin was converted to an [18F]fluorohydrin‐functionalized nitrile intermediate through regiospecific epoxide ring opening with cyanide; this 2‐step conversion assessed by radio‐ TLC averaged 85 ± 9% (M ± SD, n=7) in 40 min. Hydrolysis of the HPLC‐purified intermediate nitrile was achieved enzymatically using commercially available E. coli‐derived nitrilase. (S)‐4‐[18F]fluoro‐3‐ hydroxybutyrate was isolated by solid phase extraction cartridge (anion exchange) in approx. 230 min, radiochemical purity 100% (HPLC), radiochemical yield 13 ± 2% (mean ± SD, n = 4). (R)‐4‐[18F]fluoro‐3‐ hydroxybutyrate was similarly isolated in 240 min, radiochemical purity 98.4% (HPLC), radiochemical yield 1.3% (n = 1); the enzymatic conversion step for this isomer is less efficient3 and results in a lower yield. Results and conclusions PET images of the biodistribution of (S) and (R)‐4‐[18F] fluoro‐3‐hydroxybutyrate were acquired in normal BALB/C mice. (S)‐4‐[18F]fluoro‐3‐hydroxybutyrate showed a biodistribution consistent with the structurally related metabolite D(‐)‐3‐hydroxybutyrate, including modest heart and brain uptake (SUV≈1 for both heart and brain at 60 min post injection) and a renal clearance
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pathway. (R)‐4‐[18F]fluoro‐3‐hydroxybutyrate displayed a similar but distinct uptake pattern, showing greater retention in the heart and brain regions (SUV≈1.2 in heart and ≈1.5 in brain at 60 min). Tumor uptake of (S)‐4‐[18F]fluoro‐3‐hydroxybutyrate was assessed in MCF7 (ER+) and triple negative MDA‐MB231 breast cancer xenograft mice. Both tumors demonstrated tracer uptake: SUV 0.99 ± 0.06 (mean ± SEM, n = 3, 60 min) for MCF7, SUV 0.93 ± 0.07 (n = 4, 60 min) for MDA‐ MB231. Uptake of (S)‐4‐[18F]fluoro‐3‐hydroxybutyrate was also assessed in MCF7 xenograft mice after a 24 hour fast; both an enhancement as well as an overall change in the kinetic profile of tumor uptake were observed, SUV 1.17 ± 0.04 (n = 3, 60 min), representing an 18% increase in uptake compared to the control (nonfasted) mice. This impact of nutritive status on tracer uptake is suggestive that (S)‐4‐[18F]fluoro‐3‐hydroxybutyrate bears a metabolic resemblance to the native energy substrate, D(‐)‐3‐ hydroxybutyrate. ACKNOWLEDGEMENTS The authors gratefully acknowledge the Dianne and Irving Kipnes Foundation for supporting this work. R EF E RE N C E S 1. Webber RJ, Edmond J. Utilization of L‐(+)‐3‐hydroxybutyrate, D‐ (‐)‐3‐hydroxybutyrate, acetoacetate, and glucose for respiration and lipid synthesis in the 18‐day‐old rat. J Biol Chem 1977;252(15):5222‐5226. 2. Tsai Y‐C, Chou Y‐C, Wu A‐B, et al. Stereoselective effects of 3‐ hydroxybutyrate on glucose utilization of rat cardiomyocytes. Life Sci 2006;78(12):1385‐1391.
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3. Kamila S, Zhu D, Biehl ER, Hua L. Unexpected Stereorecognition in Nitrilase‐Catalyzed Hydrolysis of β‐Hydroxy Nitriles. Org Lett 2006;8(20):4429‐4431.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-333 | In vivo evaluation of [11C]osimertinib for PET imaging of tumours expressing mutated EGFR Antonia Högnäsbacka1; Esther Kooijman1; Robert Schuit1; Marion Chomet2; Danielle Vugts1; Guus van Dongen3; Alex Poot1; Albert Windhorst1 1
Amsterdam UMC, VU University, Netherlands; 2 Amsterdam UMC, VU
University, Radiology and Nuclear Medicine, Netherlands; 3 VU University Medical center, Netherlands
Introduction Mutations in the epidermal growth factor receptor (EGFR) are observed in 12‐47% of adenocarcinoma non‐small‐cell lung cancers (NSCLC).i Tumours expressing primary EGFR mutations are particularly sensitive to treatment with first‐ or second‐generation tyrosine kinase inhibitors (TKIs). Unfortunately, these tumours will ultimately develop treatment resistance, most commonly due to a secondary T790M mutation.ii,iii Osimertinib is currently the only clinical treatment option for patients with T790M mutation positive tumours but is also able to inhibit primary mutations.
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It has two known main metabolites, both demethylated products (AZ5104 and AZ7550, Figure 1A), making it ideal for carbon‐11 labelling.iv By creating a PET tracer based on osimertinib, a non‐invasive tool for determining the EGFR mutational status of NSCLC is created, allowing personalized treatment to be prescribed to patients with these mutations. Aim The aim of this project is to synthesize and evaluate [11C] osimertinib, labelled at two different positions to compare the metabolism of [11C]osimertinib in vivo. In addition, the targeting potential of the tracers will be assessed in xenograft mouse models. Methods [11C]Osimertinib‐1 and ‐2 were obtained by 11C‐methylation of AZ5104 or AZ7550. The tracers were purified by semi‐preparative HPLC and formulated, yielding an injectable solution (Figure 1A). The metabolism of the tracers was evaluated in 12 female nu/nu mice. 13‐ 24 MBq tracer was injected via ocular plexus, and the
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mice were subsequently sacrificed at 5, 15, and 45 minutes post‐injection (p.i.). 0.6–1 mL blood was collected via heart puncture, and the metabolism was measured by radio‐HPLC on a Dionex Ultimate 3000 system. The separation was achieved using acetonitrile in ammonium phosphate solution (pH 2.6) as eluent, and a suitable column (1: VisionHT C18, 2: Alltima C18 (250 × 10 mm, 5 μm)). The tumour targeting potential of [11C]osimertinib‐1 was evaluated in vivo in xenografted female nu/nu mice (A549 (wild‐type EGFR), HCC827 (Del19), and H1975 (T790M)), which were sacrificed at 5, 15, and 45 minutes p.i. 13‐24 MBq of [11C]osimertinib‐1 was injected via ocular plexus, and the mice were subsequently sacrificed at 5, 15, and 45 minutes p.i. Blood, heart, lungs, liver, kidney, head, muscle, skin, brain, left and right tumour were collected, weighed, and counted for radioactivity in a Wallac Compugamma 1210 counter. The percentage of the injected dose per gram of tissue (%ID/g) was calculated.
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Results and discussion [11C]Osimertinib‐1 and ‐2 were obtained in 15 ± 4% and 8 ± 0% decay corrected yield (end of bombardment), molar activity of 280 ± 23 and 137 ± 12 GBq/μmol (end of synthesis), and a radiochemical purity of 88 ± 7% and 99 ± 1%, respectively. In blood plasma, metabolite analysis showed 8 ± 2% of [11C]Osimertinib‐1 at 5 minutes p.i., while 9 ± 0% parent tracer could be detected at 45 minutes. [11C]osimertinib‐2 proved to be more stable with 28 ± 5% of parent detectable 5 minutes p.i. and 15 ± 3% at 45 minutes p.i. [11C]Osimertinib‐1 accumulated both in metabolic organs (kidney and liver) and well‐perfused tissues like the heart and lungs and cleared rapidly from the blood (1.23 ± 0.27%ID/g for A549, 1.10 ± 0.17 %ID/g for HCC827 and 0.95 ± 0.06%ID/g for H1975 5 minutes p.i.). All tumours showed increased uptake over time (Figure 1B). Conclusion [11C]Osimertinib‐2 is metabolically more stable than [11C]osimertinib‐1. While [11C]osimertinib‐1 exhibited high uptake in the primary mutated cell line, the difference between the uptake in the secondary mutated cell line and the wild‐type EGFR expressing cell line is less defined. The tumour targeting potential of [11C] osimertinib‐2 is currently under investigation. Funding This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska‐Curie grant agreement No 675417
R EF E RE N C E S 1. Midha Anita et al., Am J Cancer Res 2015; 5 (9): 2892–2911 2. Sequist Lecia V. et al., J Clin Oncol 2013; 31:3327‐34 3. Pao William et al.,PLoS Med 2005; 2 (3): e73 4. Dickinson Paul A. et al., Drug Metab Dispos 2016, 44 (8) 1201‐1212
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-334 | Evaluation of tryptophan derivative, [18F]trifluoromethyl‐L‐tryptophan ([18F]CF3‐L‐ Trp) as PET/MR agent for detection of prostate cancer: Comparison with L‐[11C]Methionine ([11C]MET) Ho Young Kim1; Ji Youn Lee1; Hyeyeon Seo; Yun‐Sang Lee2; Jae Min Jeong2
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Seoul National University, Republic of Korea; 2 Seoul National University
Hospital, Republic of Korea
Objectives Prostate cancer is a common cancer that accounts for about 20% of male cancer deaths and is caused by abnormally proliferating cells of the prostate gland. Amino acid transporters, such as alanine‐serine‐cysteine transporter 2 (ASCT2) and LAT‐1, are upregulated in prostate cancer to provide nutrients for tumor cell growth [1]. Therefore, radiolabeled amino acid derivatives can be useful to localize prostate cancer. In this study, we evaluated the uptake of [18F]trifluoromethyl‐L‐tryptophan ([18F]CF3‐L‐Trp) in prostate cancer cell (22Rv1 and PC‐3) xenograft mice and compared the uptake of [18F] CF3‐L‐Trp with L‐[11C]Methionine (L‐[11C]MET) in 22Rv1 xenograft mice. Methods [18F]CF3‐L‐Trp was prepared from protected 2‐iodo‐L‐ tryptophan by copper(I) mediated [18F] trifluoromethylation and acid‐hydrolysis, and L‐[11C] MET was prepared from L‐homoocysteine thiolactone by [11C]methylation. [18F]CF3‐L‐Trp (10.3‐13.1 MBq) and L‐[11C]MET (10.0 MBq) were intravenously injected into 22Rv1 (PSMA(+)) or PC‐3 (PSMA(−)) xenograft mice. PET and T2‐weighted MR images were simultaneously obtained by sim PET/MR from 20 to 120 min after injection. For evaluation of the uptake of [18F]CF3‐ L‐Trp and L‐[11C]MET, the maximum standardized uptake values (SUVmax) were obtained from reconstructed data of each PET imaging system. For PET image analysis, MR images and [18F]CF3‐L‐Trp and L‐ [11C]MET PET images were fused by using amide software. Results In T2‐weighted MR images, tumor which was established at the right shoulder was identified in 22Rv1 (PSMA(+)) or PC‐3 (PSMA(−)) xenograft mice. Tumor uptake [SUVmax] of [18F]CF3‐L‐Trp in 22Rv1 xenograft mice was 0.499 at 60 min post injection and distinct from surrounding area in PET images. On the other hand, the tumor uptake [SUVmax] of L‐[11C]MET in 22Rv1 xenograft mice was 0.095 at 60 min post injection showing the high uptake in the liver. Tumor uptake [SUVmax] of [18F]CF3‐L‐Trp in PC‐3 xenograft mice was 0.302 at 60 min post injection and was lower than that of 22Rv1 xenograft mice. Conclusion We assessed the performance of [18F]CF3‐L‐Trp in prostate cancer and confirmed the increased uptake in prostate cancer, especially in PSMA positive prostate cancer. Also, [18F]CF3‐L‐Trp showed more specific uptake than
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L‐[11C]MET for prostate cancer in 22Rv1 xenograft mice. We expect that the combined image of [18F]CF3‐L‐Trp PET and MR will provide more accurate diagnostic information to localize prostate cancer.
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Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( Im a g in g ) P-335 | Radiosynthesis, in vitro and in vivo
R EF E RE N C E S 1. Oka S, et al. (2012) Nucl Med Biol, 39, 109‐119.
ACKNOWLEDGEMENTS This research was supported by National R&D Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 1711026888 and NRF‐2016M2C 2A1937981) and a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI15C3093).
evaluation of [18F]Fluorphenylglutamine and [18F]Fluorbiphenylglutamine as novel ASCT‐2 directed tumor tracers. Tristan Baguet4; Jeroen Verhoeven4; Stef De Lombaerde4; Sarah Piron4; Benedicte Descamps1; Christian Vanhove1; Hassan Beyzavi2; Filip De Vos3 1
IbiTech‐MEDISIP‐INFINITY, Belgium; 2 Department of chemistry and
biochemistry/University of Arkansas, United States; 3 Laboratory of Radiopharmacy, Belgium; 4 Ghent University, Belgium
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Introduction PET‐imaging and [18F]FDG, these two words are almost inseparable and with reason. [18F]FDG remains the golden standard in PET oncology. However, for several tumor types, [18F]FDG is not able to provide good quantification (e.g., brain‐, prostate‐, coloectal cancer). Insights on the role of glutamine in the molecular pathology of cancer have raised the interest in glutamine based PET tracers as an alternative for [18F]FDG. In particular, tumors that switched from glycolysis to glutaminolysis seem to be promising for glutamine‐based PET‐imaging. To further explore this, we developed two novel [18F]‐labelled glutamine derivates: [18F]Fluorphenylglutamine ([18F]FPG) and [18F]Fluorbiphenylglutamine ([18F]FBPG). Methods Both tracers were labelled with [18F] via an aromatic fluorination method described by Beyzavi et al. [18F‐], derived from cyclotron, was loaded on a HCO3 Sep‐Pak column. A mixture of precursor (4 mg), imidazolium chloride (18 mg), and ruthenium complex (6 mg) was used to elute the [18F]fluoride. Subsequently, the elute was placed in warm oil bath (125°C) for 30 minutes. Upon completion of the reaction, the mixture was trapped on a C18 Sep‐ Pak, washed with 5.0 mL H2O and eluted with 1.0 mL acetonitrile. After evaporation of the acetonitrile, the compound was deprotected by adding 200 μL of HCl (4 M/dioxane) and placing it in a warm oil bath (90°C)
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for 3.5 minutes. After deprotection, the compound was purified by means of HPLC. Compound confirmation and determination of radiochemical purity were done by comparing the radiolabeled tracer with cold reference compound on analytical HPLC. Stability was assessed by injection into analytical HPLC after incubating the tracer formulation at 37°C for three hours. For the in vitro evaluation, Ki values were determined with [3H]‐glutamine uptake experiments. Michaelis‐Menten curves were determined for [3H]‐glutamine uptake in PC‐3 cells in absence and presence of [19F]FPG and [19F]FBPG. The data were processed in Graphpad (prism 5.0) to obtain Km and Km,app values which in turn were used to determine Ki values. In vivo evaluation was done in PC‐3 xenografts. Five swiss nu/nu mice were inoculated in the flank with 5 × 106 PC‐3 cells at the age of six weeks. Seven weeks post inoculation dynamic μPET‐scans were acquired for one hour after the injection of 18.5 MBq radiotracer. Tumor uptake was analyzed by drawing volumes of interest around the tumor with AMIDE. The uptake in tumor tissue was compared to uptake in muscle tissue to obtain tumor‐to‐muscle ratios (T/M). Results Both tracers were successfully labeled with a radiochemical purities of more than 95%. [18F]FPG was synthesized with a total synthesis yield of 18.46% (±4.18%) and a synthesis time of 88 minutes (±4 min). The synthesis of [18F]
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FBPG had a total synthesis yield of 8.05% (±3.25%) and a total synthesis time of 97 minutes (±12 min). No degradation was seen for both tracers. The uptake experiments in PC‐3 cells showed Ki values of 2476 μM and 516 μM for, respectively, FPG and FBPG. Both tracers showed in vivo uptake in the tumor. A T/M ratio of 1.26 (±0.18) was seen for [18F]FBPG and 1.70 (±0.23) for [18F]FPG. Conclusion We hereby report two novel glutamine‐derived PET tracers. Both tracers can be labeled with [18F]fluoride and show good yields and total synthesis time. Both in vitro and in vivo [18F]FPG shows better potential than [18F]FBPG with better Ki and T/M values.
Poster Cate gory: Radiola bele d Compounds ‐ Oncology (Imaging) P-336 | N‐Methyl carboxylic acid substituted glutamate‐urea‐lysine analogues, more hydrophilic PSMA inhibitors with high binding affinity Byoung Se Lee1; So Young Chu1; Hyeon Jin Jeong1; Woon Jung Jung1; Hee Jung Moon1; Min Hwan Kim1; Jae Seong Kim1; Yong Jin Lee2; Kyo Chul Lee3; Mi Hyun Kim1; Sang Moo Lim3; Dae Yoon Chi4 1
FutureChem, Korea, Republic of; 2 Korea Institute of Radiological
&Medicals Sciences, Korea, Republic of; 3 KIRAMS, Korea, Republic of; 4
Department of Chemistry, Sogang University, Korea, Republic of
Objectives Glutamate‐urea‐lysine (GUL) is a well‐known basic structure for specific binding to PSMA protein. There have been many efforts to find additional interaction between GUL‐based molecules and PSMA binding region. As a result, arene‐cation interaction in arginine patch region and remote hydrophobic interaction were discovered. For better binding, hydrophobic groups are commonly required in these regions. However, the additional groups increase the lipophilicity of inhibitors, worsening in vivo pharmacokinetic properties and enhancing non‐specific binding. The aim of this study is to find a more hydrophilic PSMA inhibitor with high binding affinity. Methods To find another interaction, we focused on the arginine patch region in PSMA. A carboxylic acid instead of lipophilic arene groups such as benzene, pyridine, and naphthalene was thought to make ionic interaction with protonated arginine residue of PSMA. A series of
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compounds were synthesized from tert‐butyl protected GUL intermediate to confirm our hypothesis. In vitro competition binding assay was performed using 125 I‐labeled IMP‐1095 and 22RV1 prostate tumor cell line. Results The in vitro binding assay revealed that while N‐acetyl GUL compound showed low binding affinity of 37.25 ± 2.31 nM (Ki value). The N‐acetyl, N‐methyl carboxylic acid GUL compound showed 3.31 ± 0.25 nM. In addition, the N‐acetyl, N‐ethyl carboxylic acid GUL compound was also found to have a good binding affinity (3.39 ± 0.96 nM). As a result, it was confirmed that the carboxylic acid moiety is effective for increasing the binding affinity to PSMA up to about 10 times. In literature, this salt bridge interaction between carboxylate and arginine is known to be somewhat greater than arene‐cation interaction. From this result, we synthesized 18F‐labeled GUL compound bearing carboxylic acid via CuAAC click chemistry in 45.0% decay‐corrected radiochemical yield. Binding affinity of this molecule was determined to be 3.02 ± 0.11 nM and lipophilicity (logP) was measured using PBS buffer and n‐octanol to be −2.40. Subsequently, the 18F‐labeled compound was injected to PC‐3 PIP(+) and flu(−) bearing mouse, and microPET images were then obtained. The microPET experiment showed high tumor uptake of the 18F‐labeled compound and fast background clearance including liver and spleen. Conclusion We found that the carboxylic acid group is able to interact tightly with arginine patch region of PSMA through a salt bridge interaction. This finding is expected to be applied to find better radiopharmaceuticals for diagnosis and therapy of prostate cancer.
P-418 | Synthesis and evaluation of [18F] SuPAR for PET Imaging of DNA damage‐ dependent PARP activity Adam J. Shuhendler; Bin Shen; Lina Cui; Zixin Chen; Jianghong Rao; Frederick T. Chin Department of Radiology, Molecular Imaging Program at Stanford (MIPS), USA
Objective Poly(ADP ribose) polymerase (PARP) repairs single‐ strand DNA breaks1 and its activity can serve as a biomarker for image‐based assessments for tumor radiation response that is critically needed for monitoring the
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efficacy of clinical radiation therapy. We present the radiosynthesis of a novel substrate‐based PARP activity probe ([18F]SuPAR) for PET imaging of PARP activity related to radiation therapy response in a murine tumor model. Unlike current radiolabeled derivatives of existing PARP‐1/2 inhibitors that bind to PARP‐1/2 and outcompete nicotinamide adenine dinucleotide (NAD) for the catalytic site of the enzyme, [18F]SuPAR is a radiofluorinated NAD analog that can be recognized by PARP‐1/2 and incorporated into the long‐branched polymers of poly (ADP ribose) (Fig 1A). Therefore, we will demonstrate that [18F]SuPAR can directly image PARP‐ 1 activity rather than cellular expression levels of PARP‐ 1, which can afford a more accurate therapeutic outcome.2 Method [18F]SuPAR was prepared through azide‐alkyne Hüisgen cycloaddition between [18F]azide and modified NAD accelerated by Bim(C4A)3 (Fig 1A). In order to assess the enzyme specificity of [18F]SuPAR, an FDA‐approved PARP‐1/2 inhibitor talazoparib (Talzenna, Pfizer) was administered following the peak response of MDAMB‐
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231 (10 Gy, 24 h post‐irradiation) tumor as measured by [18F]SuPAR imaging. Mice were administered a single p. o. dose of talazoparib (1 mg/kg) and imaged with [18F] SuPAR 45 min dynamic PET/CT that began at 2 h post‐ treatment to allow for enzyme inhibition. Results [18F]SuPAR was obtained with an overall radiochemical yield of 3.6 ± 0.6% (n = 10, decay‐corrected to end‐of‐synthesis) and molar radioactivity of 1.1 ± 0.3 Ci/μmol (n = 10). A substantial reduction in [18F]SuPAR uptake back to background (naïve) levels in MDA‐MB‐231 tumors was observed by PET imaging following talazoparib treatment (Fig 1B i‐iii), resulting in a significant reduction in AUC (from 72.1 ± 3.9 to 46.7 ± 6.3%ID/min cc‐1; Fig 1C, D, P < 0.05). Although Talazoparib‐induced inhibition of PARP‐1/2 resulted in a trend of decreased [18F]SuPAR uptake in HeLa tumors (Fig 1B iv‐vi), the reduction in AUC was not statistically significant (from 97.4 ± 17.5 to 76.8 ± 11.6%ID/min cc‐1; Fig 1E,F, P > 0.05). Conclusion This new probe provides a conceptual framework for the design and implementation of novel PARP‐1/2‐targeted
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substrate‐based molecular imaging reporters. While different degrees of inhibition with talazoparib were observed between the tumor types tested, [18F]SuPAR is able to sense increased PARP‐1/2 activity above background in both tumor models. The ability to map DNA damage‐dependent PARP‐1/2 activity with [18F]SuPAR could provide early information regarding the efficacy of applied radiotherapy that could help clinicians adjust treatment regimens for cancer patients.
R EF E RE N C E S 1. Gibson BA et al. Nat. Rev. Mol. Cell Biol. 2012, 13, 411‐424. 2. Michels J et al. Cancer Res. 2013, 73, 2271‐2280.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranos tics ) P-337 | 131I‐AuNPs‐TAT particles target cells nuclei in colon cancer for enhanced radioisotope therapy Weiwei Su1,2,3,4; Changjing Zuo1,2,3,4 1
FutureChem, Korea, Republic of; 2 Korea Institute of Radiological
&Medicals Sciences, Korea, Republic of; 3 KIRAMS, Korea, Republic of; 4
Department of Chemistry, Sogang University, Korea, Republic of
Objectives To improve the therapeutic efficiency of radionuclide in HCT116 colon tumor by utilizing a nuclide nanocomposites of radioactive iodine‐131 (131I), Au nanoparticles (AuNPs), and cell penetrating peptide (TAT). Methods AuNPs (41.4 nm) modified with PEG was conjuncted with TAT (Au@PEG‐TAT, 58.5 nm) for the function of cell‐nucleus targeting. Radioactive 131I was labeled to AuNPs (131I‐AuNPs), TAT (131I‐TAT), and AuNPs@PEG‐TAT (131I‐AuNPs‐TAT), respectively. Flow cytometry and clone formation assay were conducted to access cell apoptosis, cycle, ROS level, and proliferation. Damage degree of DNA was detected by γH2AX staining. BALB/c nude mice bearing subcutaneous tumors (average diameter, 6 mm) were intratumorly injected with different drugs, with dose of 500 μCi 131I 100 μg AuNPs and 10 μg TAT per mouse. Drug distribution in vivo was observed by SPECT/CT, respectively, at 2 h, 6 h, 12 h,
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24 h, 48 h, 96 h, and 168 h P.I. Mice body weight and tumor size were measured every two days, and tumor tissue was extracted at 28 P.I. for H&E staining, TUNEL assay, and immunohistochemical analysis for CD19, CD56, TNF‐α, and ki‐67. Overall survival of each mouse was recorded. Results Improved cell nucleus uptake of AuNPs@PEG‐TAT than AuNPs was confirmed by confocal microscopy and Bio‐ TEM. CCK‐8 assay indicated the optimal concentration of 131I, AuNPs, and TAT was 500 μCi/ml, 100 ug/ml, and 10 ug/ml, respectively. Cells treated with 131 I‐AuNPs‐TAT showed significantly increased apoptosis rate (73.12%) than 131I‐AuNPs (61.82%), 131I‐TAT(46.96%) and 131I (31.44%), and the colony‐forming efficiency was 1.04%, 1.11%, 1.59%, and 1.98% with equal 131I of 40 μCi. 131I‐AuNPs‐TAT generated more ROS than other groups (56.55% vs. 5.94%, 29.21, 42.69%, 46.22%), and caused 29.7 ± 15.9, 18.67 ± 19.33, 9.17 ± 13.41, and 1.31 ± 0.41 times of DNA double‐strand breakage than others. Cells in G2/M phase increased from 6.78% (control) to 45.12% (131I‐AuNPs‐TAT). SPECT/CT imaging showed stable retention of 131I‐AuNPs for 12 h and 131I‐ AuNPs‐TAT for 36 h in the injected point. Respectively, at 48 h and 96 h P.I., 2.75% and 1.06% of 131I‐AuNPs and 131I‐AuNPs‐TAT was transported to thyroid. Efficient inhibition of tumor growth was found in 131I‐AuNPs‐TAT (V1/V0, 1.62 ± 0) compared to 131I‐AuNPs (2.51 ± 0.41), 131 I‐TAT (4.46 ± 0.31), 131I (5.25 ± 0.14), and control group (8.08 ± 0.14) , and had relatively longer survival time. Additionally, the increased anti‐cancer CD19+ and CD56+ effector in 131I‐AuNPs‐TAT group indicated the enhanced immunophagocytosis of B and NK cells to cancer cells. Conclusions The present study for the first time utilizing braking radiation between AuNPs and β‐ray to improve therapeutic efficacy. Apart from enlarging the radiation range, the generated X‐ray also potentiated cancer immunity responses as previous study[1] reported, thus collectively contributed to enhanced therapeutic efficiency. ACKNOWLEDGMENTS The authors declare that they have no competing interests. RE FER EN CES 1. Kojima S, Ishida H, Takahashi M, et al. Elevation of glutathione induced by low‐dose gamma rays and its involvement in increased natural killer activity[J]. Radiat Res, 2002, 157(3):275‐280.
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Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranostics ) P-338 | CD146‐targeted, multimodal image‐ guided photoimmunotherapy of melanoma Weijun Wei1; Dawei Jiang2; Dalong Ni; Lei Kang3; Jonathan Engle2; Weibo Cai2 1
Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China;
2
University of Wisconsin‐Madison, United States; 3 Peking University First
Hospital, China
Purpose For melanoma resistant to molecularly‐targeted therapy and immunotherapy, new treatment strategies are urgently needed. A molecularly‐targeted theranostic pair may thus be of high importance, as the diagnostic probe can facilitate patient stratification and the therapeutic agent can treat melanoma in a marker‐dependent manner.
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Methods In this study, flow cytometry was used to assess CD146 expression levels on melanoma cell lines. Based on YY146, a CD146‐specific monoclonal antibody, the imaging probe 89Zr‐Df‐YY146 was synthesized, and its noninvasive diagnostic performance was evaluated by positron emission tomography (PET). Furthermore, IR700‐YY146, a photoimmunotherapy (PIT) agent, was developed and the therapeutic effect of near‐infrared IR700‐YY146 PIT was assessed in both in vitro and in vivo melanoma models. Results We reported that CD146 was highly expressed in A375 and SK‐MEL‐5 cell lines. 89Zr‐Df‐YY146 PET readily detected the CD146‐positive A375 melanoma xenografts. Tumor accumulation of 89Zr‐Df‐YY146 peaked at 72 h post‐injection with an uptake value of 24. ± 3.28% ID/g, whereas the highest uptake of the nonspecific probe 89 Zr‐Df‐IgG was 4.80 ± 1.75% ID/g. More importantly, near‐infrared PIT using IR700‐YY146 effectively inhibited the growth of A375 tumors, resulting in the production of reactive oxygen species, significantly decreased glucose
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metabolism, and tumor‐specific downregulation of CD146. Conclusion We demonstrated that 89Zr‐Df‐YY146 and IR700‐YY146 are a promising theranostic pair with the former revealing CD146 expression in melanoma as a PET probe and the latter specifically treating CD146‐positive melanoma as an effective PIT agent.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranos tics ) P-339 | A novel tracer for GD2‐positive neuroblastoma Sarah Spreckelmeyer; Kerstin Schoenbeck; Julian Rogasch; Nicola Beindorff; Holger Lode; Johannes Schulte; Patrick Hundsdoerfer; Holger Amthauer
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Charité Berlin—Nuclear Medicine Department—Radiopharmacy, Germany
Neuroblastoma is a malignant tumor developing from progenitor cells of the sympathetic nervous system. 7‐8% of all diagnosed malignancies in children are neuroblastoma. In Germany, 150 children per year are diagnosed with this disease. Initial diagnostics comprise imaging techniques including ultrasound, MRI as well as SPECT scans with 123I‐metaiodobenzylguanidine (mIBG). Unfortunately, 5‐20% of neuroblastoma are mIBG negative. In contrast, nearly 100% of neuroblastoma express disialoganglioside GD2. The chimeric antibody ch14.18/ CHO (Dinutuximab beta) is highly specific for GD2 and demonstrated improved overall survival in neuroblastoma patients in a clinical phase 3 study. Our goal is to develop a Dinutuximab beta‐based bifunctional radiopharmaceutical for targeted diagnostics and therapy in neuroblastoma. Furthermore, we aim to perform in vitro and in vivo experiments in order to elucidate the
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functionality of our tracers. The radiotracers were synthesized using established protocols. The logP values were assessed with the octanol/PBS coefficient. Radiochemical yields were calculated by iTLCs. For the in vitro and in vivo experiments, IMR‐32 cells were used as they express the GD2 epitope. Affinity studies were performed using FACS analysis and immunofluorescence microscopy with our tracers at different incubation times and different temperatures with DTPA‐Rituximab as negative control. In vivo binding properties of the radiotracers were validated in CAM assays. Two bifunctional chelators (DOTA‐ Dinutuximab beta and DTPA‐Dinutuximab beta, Figure 1) were successfully synthesized and radiolabelled with [68Ga]Ga3+ and [177Lu]Lu3+ for imaging or therapeutic purposes, respectively. Both tracers show labeling efficiencies of >90 % with a marked stability in human serum in vitro. GD2‐positive IMR‐32 cells were used to validate the affinity of the bifunctional tracers compared to the unaltered antibody. The functionality of the tracers were proven by a CAM assay in vivo. Concerning the affinity studies, we show significant differences between experiments performed at 37°C vs. 4°C. To conclude, two bifunctional chelators were successfully linked to Dinutuximab beta and they show promising radiolabeling properties—[68Ga] Ga3+ for immunoPET imaging and [177Lu]Lu3+ for combined radioimmunotherapy. Currently, we are investigating the biodistribution and imaging properties of the promising tracers in GD2‐positive xenograft mice experiments.
Poster Category: Radiola beled Compounds ‐ Oncology (Therapy & Theranos tics ) P-340 | Synthesis of [211At]MABG using remote‐controlled synthesizer and quality evaluation Miho Aoki1; Katsuyuki Minegishi2; Ken‐ichi Nishijima1; Hisashi Suzuki3; Shigenori Sasaki4; Kohshin Washiyama1;
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Songji Zhao1; Kotaro Nagatsu5; Ming‐Rong Zhang6; Kazuhiro Takahashi1 1
Fukushima Medical University, Japan; 2 National Institutes for Quantum
and Radiological Science and Technology (QST), National Institute of Radiological Sciences (NIRS), Japan; 3 National Institutes for Quantum and Radiological Science and Technology, National Institute of Radiological Sciences, Japan; 4 SHI Accelerator Service Ltd., Japan; 5
National Institute of Radiological Sciences, Japan; 6 Department of
Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
Objectives Pheochromocytoma is a known neuroendocrine tumor. Around 10% of pheochromocytomas are malignant and metastasize to bone, lung, etc. It is a refractory disease lacking an effective treatment. For malignant pheochromocytoma, treatment using with meta‐[131I] 131 iodobenzylguanidine ([ I]MIBG) has been performed, but its therapeutic effect is limited. By applying α‐rays with a higher biological effect and shorter range than β‐rays to targeted radioisotope therapy, not only higher therapeutic effect can be expected but also radiation damage to normal tissues can be minimized. Therefore, meta‐[211At]astatobenzylguanidine ([211At]MABG) has been developed using astatine‐211 (211At, half‐life: 7.2 h), which emits α‐rays and has chemical properties similar to iodine.1 Its high accumulation in tumors and strong tumor volume‐reducing effect in pheochromocytoma model mice have already been reported.2 Currently, Our facility is planning to develop [211At] MABG for human clinical research in collaboration with the National Institutes for Quantum and Radiological Science and Technology (QST), which reported the therapeutic effect in mice. The aim is to synthesize [211At]MABG with a remotely controlled synthesizer using in‐house produced 211At at the Fukushima Medical University (FMU).
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Methods We produced 211At using 209Bi (α, 2n) 211At reaction by the MP‐30 cyclotron in FMU. The purification was carried out by dry distillation and obtained 211At as chloroform solution. An [211At]MABG‐remotely controlled synthesizer, designed and produced by the QST group, was installed in the glove box. 211At solution (13.5– 141.4 MBq, ca. 0.1 mL) was introduced into the synthesizer and [211At]MABG was synthesized from the precursor, meta‐trimethylsilylbenzylguanidine hemisulfate (0.25 mg, 0.92 μmol) by electrophilic substitution reaction with N‐chlorosuccinimide (NCS, 50 μL as saturated solution in methanol) and trifluoroacetic acid (TFA, 0.35 mL) at 70°C for 10 min. Purification was carried out by solid phase extraction (Sep‐Pak tC18 Plus Light Cartridge, Waters). After washing with water (0.5 mL), [211At] MABG was eluted with 5% ethanol aqueous solution (2 mL). The quality of [211At]MABG was confirmed using radio‐HPLC. Results When [211At]MABG was synthesized using the synthesizer, the radiochemical yield was 59 ± 5%, and the synthesis time was 42 ± 2 minutes (n = 3). The maximum yield was 61.4 MBq (EOS). By solid‐phase extraction, it was possible to remove most of regents including NCS, precursor, and unreacted 211At. The radiochemical purity was >95%. Conclusions We succeeded in synthesizing [211At]MABG using 211At produced in FMU, and stable production was enabled in the yield and the synthesis time by using the synthesizer. R EF E RE N C E S 1. Vaidyanathan G, Zalutsky MR. Bioconjug Chem 1992;3:499. 2. Ohshima Y, Sudo H, Watanabe S, Nagatsu K, Tsuji AB, Sakashita T, et al. Eur J Nucl Med Mol Imaging 2018; 45: 999–1010
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Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( T h e r a p y & Th e r a n o s t i c s ) P-341 | [89Zr]ZrDFO‐CR011 PET imaging to predict response to an antibody drug conjugate for gpNMB in triple negative breast cancer Supum Lee1; Alessandra Cavaliere2; Sun Suxia3; Xianhong Xiang4; Tibor Keler5; Sharon Michelhaugh6; Tim Mulnix7; Stephen Maher8; Richard Carson9; Yiyun Huang10,11; Alfred Bothwell8; Sandeep Mittal1; Bernadette Marquez‐Nostra3 1
Yale School of Medicine, United States; 2 Department of Radiology and
Biomedical Imaging, Yale University, United States; 3 Yale University, United States; 4 The First Affiliated Hospital of Sun Yat‐Sen University , China; 5 Celldex Therapeutics, Inc., United States; 6 Wayne State University, United States; 7 Yale University PET Center, United States; 8
Yale University School of Medicine, United States; 9 Yale PET Center,
Department of Radiology and Biomedical Imaging, Yale University School of Medicine, United States;
10
PET Center, Department of Radiology and
Biomedical Imaging, Yale University School of Medicine, United States; 11
Wayne State University/Karmanos Cancer Institute, United States
Objectives Glycoprotein non‐metastatic B (gpNMB) is an emerging cell surface target for triple negative breast cancer (TNBC) (1‐3). The goal of this study is to evaluate the PET imaging of gpNMB using the [89Zr]ZrDFO‐CR011 antibody in predicting response to its antibody drug conjugate variant, glembatumumab vedotin (CDX‐011) in TNBC xenograft models. Methods gpNMB‐positive MDA‐MB‐468 (n = 5) and gpNMB‐negative MDA‐MB‐231 (n = 5) were developed to determine the threshold of positivity for gpNMB in vivo. We then evaluated brain metastasis (designated W15, n = 4) and primary tumor (designated MK24, n = 2) tissues of TNBC as patient‐derived xenograft models (PDX), given their overexpression of gpNMB. Mice were injected with 1.5‐1.85 MBq of [89Zr]ZrDFO‐CR011 via tail vein and imaged at 7 days post‐injection (baseline). Mice were
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then treated with 20 mg/kg of CDX‐011 at 1 day after baseline PET. PET imaging of the W15 model was repeated at 41 days after CDX‐011 therapy, and a second therapeutic dose of CDX‐011 was administered to the PDX model at 49 days after initial therapy. A similar workflow was performed for the MK24 model, with mice treated with either CDX‐011 or saline (control). Regions of interest (ROI) were drawn on the tumor using CT images as a guide, and radiotracer uptake was quantified by calculating mean standard uptake values (SUV) from decay‐corrected ROI activity concentrations. Tumor volumes were measured using calipers to monitor response. Results MDA‐MB‐468 xenografts demonstrated a baseline mean SUV of 4.26 ± 1.54 in the tumor and responded completely to CDX‐011 therapy with no palpable tumors at endpoint, while MDA‐MB‐231 xenografts had a baseline mean SUV of 1.62 ± 0.53. MDA‐MB‐231 tumors progressed, reaching an average tumor volume of 428 ± 171 mm3 at 30‐33 days post‐CDX‐011. Categorizing tumor SUVs from cell‐derived xenografts into response groups reveals a threshold of positivity for gpNMB expression at an SUV of about 2.5, which could be applied to determine eligibility for gpNMB‐targeted therapy. The gpNMB‐positive W15 PDX model demonstrated a baseline mean SUV of 4.64 ± 0.76. This PDX responded to the first dose of CDX‐011 with an 86% reduction in tumor volume over 23 days post CDX‐011. However, this PDX began to rebound with an 89% increase in tumor volume between 23 and 30 days post CDX‐011. W15 PDX models were imaged again at 41 days post CDX‐011 and displayed decreased but positive tumor uptake of [89Zr] ZrDFO‐CR011 (mean SUV of 3.19 ± 1.40). W15 PDXs responded to the second round of treatment, with an 86% reduction in tumor volume over 13 days after re‐ treatment. The CDX‐011‐treated MK24 PDX model (n = 1) displayed a baseline mean SUV of 2.49 and experienced an 84% decrease in tumor volume over 16 days post‐therapy. Another cohort (n = 1) of MK24 tumor treated with saline experienced a 216% increase in tumor volume over 16 days post‐therapy. Based on these pilot studies, we are currently investigating larger cohorts. As expected, gpNMB‐positive TNBC xenograft models responded to CDX‐011 ADC, while gpNMB‐negative models did not. Conclusion This preliminary study demonstrates that PET imaging of gpNMB expression has the ability to predict initial response to antibody drug conjugates targeting this receptor.
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ACKNOWLEDGEMENTS We would like to thank the Isotope Production teams at Washington University in St. Louis and University of Alabama Birmingham for providing 89Zr; Hyosuk Seo for technical assistance; Yale PET Center for their support and training; and the NIH/NCI for funding (R00CA201601). RE FER EN CES 1. Maric G, Rose AA, Annis MG, Siegel PM. Glycoprotein non‐metastatic b (GPNMB): A metastatic mediator and emerging therapeutic target in cancer. Onco Targets Ther 2013;6:839‐52. 2. Maric G, Annis MG, Dong Z, Rose AA, Ng S, Perkins D, et al. GPNMB cooperates with neuropilin‐1 to promote mammary tumor growth and engages integrin alpha5beta1 for efficient breast cancer metastasis. Oncogene 2015;34(43):5494‐504. 3. Oyewumi MO, Manickavasagam D, Novak K, Wehrung D, Paulic N, Moussa FM, et al. Osteoactivin (GPNMB) ectodomain protein promotes growth and invasive behavior of human lung cancer cells. Oncotarget 2016;7(12):13932‐44.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( T h e r a p y & Th e r a n o s t i c s ) P-342 | Theranostics of Glioma Mice with a novel agent
111
In‐DOTA‐AEK22
Yu Tang1; Zhonghui Liao1; Weihao Liu1; Yuhao Li1; Yingjiang Hu1; Huawei Cai1; Huan Ma2; Jijun Yang1; Yuanyou Yang1; Jiali Liao1; Jiming Cai2; Ning Liu1 1
Sichuan University, China; 2 Chengdu New Radiomedicine Technology
Co. Ltd., China
Objectives Indium‐111 (111In, T1/2 = 67 h) is an excellent radionuclide for SPECT imaging, decaying by electron capture (EC) with subsequent emission of gamma photons of 173 and 245 keV. It also emits therapeutic auger and internal conversion electrons with a medium to short tissue penetration (0.02–10 μm and 200–550 μm, respectively). Thus, 111In had the potential to be used as a theranostic agent for SPECT imaging and radionuclide therapy. In our work, we explored the optimized preparation of 111In‐labeled monoclonal antibody (mAb) AEK22 (111In‐DOTA‐AEK22), and evaluated the agent for targeted imaging and treatment of epidermal growth factor receptor (EGFR) overexpressed in glioma.
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Methods To optimize the radiolabeling efficiency of 111In with DOTA‐AEK22, multiple radiolabeling conditions were performed. Radiolabeling yield, radiochemical purity, stability in vitro, and bio‐distribution were investigated to characterize 111In‐DOTA‐AEK22 for chemical and biological integrity. The in vivo behavior of this tracer was studied in mice bearing subcutaneous U87MG (EGFR‐ positive) tumors; the mice received a 3.5 ± 0.2 MBq/dose prior to SPECT/CT imaging. Then, the mice bearing U87MG tumors were further subjected to 111In‐DOTA‐ AEK22 therapy. Specifically, when the tumor size reached 0.5–0.6 cm in diameter, tumor‐bearing mice were systemically administered different doses 111In‐DOTA‐ AEK22 (~74 MBq, ~37 MBq, ~18 MBq, respectively) or AEK22, saline. The mice weights, tumor sizes, and survival rate were monitored over the treatment period. Results Quality assurance of 111In‐DOTA‐AEK22 demonstrated DFO‐AEK22 radiolabeled with 111In in pH ~3.5 with high radiolabeling yield (>90%) and radiochemical purity
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(>99%). In vitro validation showed that 111In‐DOTA‐ AEK22 had an initial immunoreactive fraction of 0.96 ± 0.1 and remained active for up to 3 days. A biodistribution study revealed excellent stability of 111In‐ DOTA‐AEK22 in vivo compared with 111In as a bone seeker. SPECT imaging studies indicated the tracer had great targeting and was specific for glioma (Fig. 1A). The tumor growth in U87MG model under 111In‐DOTA‐ AEK22 (~37 MBq) treatment was much slower than that of the control group (Fig. 1B). The treatment results demonstrated that the therapeutic groups (~37 MBq and ~18 MBq) showed significantly improved survival, compared with that of the control group of mice inoculated with U87MG cells (Fig. 1C). Conclusions These studies developed a probe 111In‐DOTA‐AEK22 with optimized synthesis. The radiotracer showed exceptional promise for imaging cancer over an extended period of time (up to 3 days). The tumors can be successfully visualized by 111In‐DOTA‐AEK22 SPECT/CT imaging and further treated by 111In‐DOTA‐AEK22,
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highlighting the high potential of using 111In‐DOTA‐ AEK22 as a theranostic agent for glioma. Fig. 1. (A) SPECT/CT imaging in subcutaneous U87MG tumor‐bearing mice at different time points after vein injection of 111In‐DOTA‐AEK22; (B) Therapeutic responses of U87MG tumor–bearing mice after various treatments; (C) Time‐to‐Sacrifice for different therapy group and control group. White arrows indicate the location of the tumors. Acknowledgments This study was supported by Key Research Development Project of Sichuan Provincial Department of Science and Technology (2018SZ0022) and the Open Project Program of Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province. R EF E RE N C E S 1. Capello A, Krenning E, Bernard B. (2005). 111In‐labelled somatostatin analogues in a rat tumour model: somatostatin receptor status and effects of peptide receptor radionuclide therapy. Eur J Nucl Med Mol Imaging 32, 1288‐1295. 2. Chow TH, Lin YY, Hwang JJ. (2009). Therapeutic efficacy evaluation of 111In‐labeled PEGylated liposomal vinorelbine in murine colon carcinoma with multimodalities of molecular imaging. J Nucl Med 50, 2073‐2081.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranostics ) P-343 | [58mCo]Co‐DOTA‐hEGF—A novel ligand for targeted Auger electron therapy of glioblastoma using convection‐enhanced delivery Vigga Laursen1; Christina Baun; Charlotte Poulsen2; Birgitte Olsen3; Johan Dam4; Andreas Jensen5; Helge Thisgaard3 1
Department of Nuclear MedicineOdense University Hospital, Odense,
Denmark; 2 Department of Urology, Odense University Hospital, Denmark; 3
Department of Nuclear Medicine, Odense University Hospital, Denmark;
4
Odense Universitetshospital, Denmark; 5 DTU Nutech, Technical
University of Denmark, Denmark
Objectives The epidermal growth factor receptor (EGFR) is overexpressed in >55% of all glioblastomas. The receptor can be targeted using human epidermal growth factor (hEGF). This study investigates [58mCo]Co‐DOTA‐hEGF as
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an Auger electron emitting radiopharmaceutical for therapy of glioblastoma using convection‐enhanced delivery (CED). Methods Cobalt‐58m was produced by proton irradiation of enriched iron‐58 as previously described [1]. DOTA was conjugated to hEGF, and the resulting compound was radiolabelled with cobalt‐57 (Perkin Elmer) or cobalt‐ 58m using microwave heating in 0.2 M NaOAc (pH 5.5). Cellular uptake, subcellular distribution as well as cellular efflux were measured with [57Co]Co‐DOTA‐hEGF in the EGFR‐positive human glioblastoma cell line LN229 and the squamous carcinoma cell line A431. The therapeutic effect of [58mCo]Co‐DOTA‐hEGF was measured in vitro using the CellTiter Blue assay. Preliminary studies of the in vivo kinetics of [57Co]Co‐DOTA‐hEGF were performed using SPECT/CT and by ex vivo biodistribution at 4 and 24 hours p.i. in subcutaneous A431‐tumour bearing NOD SCID mice following intravenous injection of the compound. This was also investigated in a healthy Sprague‐Dawley rat during CED of the compound into the brain tissue for 41 hours. Results [58mCo]Co‐DOTA‐hEGF and [57Co]Co‐DOTA‐hEGF were prepared with high radiochemical purities (>97% and >96%, respectively) and with apparent molar activities of approx. 46 MBq/nmol and 0.7‐3.2 MBq/nmol, respectively. The uptake of [57Co]Co‐DOTA‐hEGF was found to be receptor‐specific in the EGFR‐positive LN229 and A431 cell lines with up to 71% internalization of the conjugate. Following incubation for 4 hours, 6‐7% of the cell‐associated radioactivity was found in the cell nucleus where the Auger electrons are most effective and more than 60% of the cell‐associated radioactivity was still retained by both cell lines 24 hours after incubation. The viability assay of LN229 cells treated with [58mCo]Co‐DOTA‐hEGF demonstrated a dose dependent therapeutic effect. A therapeutic effect was also demonstrated in A431 cells. Preliminary in vivo studies of [57Co]Co‐ DOTA‐hEGF administered intravenously in EGFR‐positive subcutaneous tumour‐bearing mice showed a receptor‐specific uptake in the tumours but a similar or even higher uptake in the liver and kidneys, making this administration route unsuitable. However, by changing the administration route to CED directly into the brain tissue of a healthy rat, the normal tissue uptake of [57Co]Co‐DOTA‐hEGF was highly reduced with no detectable activity in the kidneys and liver after 11 hours infusion. After 41 hours infusion, the brain‐to‐liver and brain‐to‐kidney activity ratios were found to be approx. 28 and 12, respectively, with a broad intracranial distribution of the compound. Hence, CED is a promising administration route of [58mCo]Co‐DOTA‐hEGF for targeted radionuclide therapy of glioblastomas.
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Conclusion An Auger electron emitting radiotherapeutic agent has been developed for treatment of EGFR expressing glioblastomas. In vitro studies have demonstrated promising therapeutic effects while preliminary in vivo studies suggested receptor‐specific uptake in subcutaneous tumours and CED to be a promising method of administration for therapy of glioblastomas. Acknowledgements This work was supported by The Independent Research Fund, Denmark (IRFD/DFF).
R EF E RE N C E S 1. Thisgaard H, Olsen BB, Dam JH, Bollen P, Mollenhauer J, and Høilund‐Carlsen PF. J Nucl Med 2014; 55:1311‐6.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranos tics ) P-344 | Evans blue attachment prolongs blood half‐life and improves radionuclide therapy in a patient‐derived xenograft model of pancreatic neuroendocrine tumors Liang Zhao1; Xuejun Wen2; Zhi Guo2; Haojun Chen1; Qin Lin1 1
The First Affiliated Hospital of Xiamen University, China; 2 Xiamen
University, China
Objectives Drug pharmacokinetics and target organ availability are defined by the drug's retention in the blood pool. Since effective therapy usually requires a sustained minimum blood concentration, drugs with short blood half‐life require higher and/or more frequent doses to maintain therapeutic levels. Such dosing levels may increase the likelihood of undesirable side effects. In order to extend the blood half‐life of drugs using albumin as a carrier molecule, we developed an “add‐on” molecule featuring (i) truncated Evans blue (EB) dye molecule, (ii) a metal chelate, and (iii) a maleimide. The “add‐on” provides moderate albumin binding, due to the EB, that prolongs half‐life in the blood, allows radiolabeling for imaging and radiotherapy, and can be easily conjugated to targeted molecules containing a free thiol group. Material and methods The truncated EB was conjugated with or 1,4,7,10‐ tetraazacyclododecane‐tetraacetic acid (DOTA) chelator. As a proof‐of‐concept, we coupled DOTA conjugated EB
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to an octreotate analogy (TATE), a somatostatin receptor‐ binding peptide (EB‐TATE). EB‐TATE were radiolabeled with Lu‐177 for SPECT imaging and targeted radiotherapy, respectively, and compared to the peptides without the “add‐on” in patient‐derived xenograft model of pancreatic neuroendocrine tumors (PDX‐PNET). Results After approval from the internal review board, samples of metastatic PNET are obtained from patient undergoing percutaneous biopsy, and the PENT‐PDX models were subsequently established. EB‐TATE was radiolabeled at a specific activity of 35‐40 GBq/μmol, with a radiochemical yield of more than 90%, and a radiochemical purity of more than 95%. The resulting radiolabeled conjugates showed prolonged circulation half‐life and enhanced tumor accumulation in somatostatin receptor‐expressing PDX‐PNETs. The tumor to background ratio (T/B) reached 13.31 ± 2.96 at 24 h, and remained 13.94 ± 3.36 at 72 h post injection. Tumor uptake was markedly increased compared to the peptides without the “add‐ on.” Regarding targeted radiotherapy, 177Lu‐EB‐TATE revealed a great inhibition of tumor growth in the 500 μCi treated group (Day 10, 401.6 ± 140.6 mm3; Day 20, 472.2 ± 149.6 mm3), compared with TATE monomer treated groups (Day 10, 755.6 ± 237.5 mm3; Day 20, 1280.8 ± 426.3 mm3) (P < 0.01) and untreated controls (Day 10, 853.7 ± 358.6 mm3; Day 20, 1395.1 ± 197.6 mm3) (P < 0.01). No systemic toxicity due to radiotherapy was observed by monitoring animal body weight. Conclusions Conjugation of our novel “add‐on” molecules to TATE peptides significantly improved both imaging and radiotherapy with these agents. These results show that our “add‐on” improves blood half‐life and tumor uptake and can transform drugs into theranostic entities. Furthermore, our PDX‐PNET model is the available, validated PDX model for PNET, and preclinical data from the use of this model suggests that 177Lu‐EB‐TATE may be an effective new treatment option for patients with PNET.
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( T h e r a p y & Th e r a n o s t i c s ) P-345 | PARaDIM—A PHITS‐based Monte Carlo tool for internal dosimetry Lukas Carter1; Troy Crawford2; Tatsuhiko Sato3; Takuya Furuta3; Wesley Bolch4; Justin Brown4; Chan Kim5; Chansoo Choi5; Jason Lewis1 1
Memorial Sloan Kettering Cancer Center, United States; 2 University of
Rhode Island, United States; 3 Japan Atomic Energy Agency, Japan;
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University of Florida, United States; 5 Hanyang University, Korea,
Republic of
Objectives Accurate dosimetry is a requisite for meaningful risk projection from low dose imaging procedures in clinical practice, as well as reliable pre‐endoradiotherapy dose planning, response assessment, and assessment of potential toxicities arising from endoradiotherapy and brachytherapy in clinical practice and preclinical cancer models (e.g., mice). Despite the prevalent use of stylized phantoms for internal dose assessment in these settings, such phantoms are becoming exceedingly outdated as methods have developed to implement voxel‐based/polygonal mesh phantoms, which better represent patient anatomy in absorbed dose calculations. In addition to dosimetry in the clinical space, polygonal mesh phantoms are applicable in small‐animal dose assessment as well as cell‐level/ microdosimetric analysis. This work describes PARaDIM (PHITS‐based Application for Radionuclide Dosimetry in Meshes), a freeware code for internal dose assessment which implements the Particle and Heavy Ion Transport code System (PHITS[1]) and tetrahedral mesh phantoms for absorbed dose calculations in all such settings. Methods PARaDIM is a Python‐based application for internal dosimetry, written and compiled within the PyCharm integrated development environment. PARaDIM provides a user‐friendly GUI for the setup of input files for internal dosimetry calculations within PHITS, based on a user‐defined or user‐specified tetrahedral mesh
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phantom, radionuclide, residence time(s), and transport simulation parameters (e.g., resolution, history number, physical models). Absorbed dose is output in two formats: mean absorbed dose to each phantom component and a voxelized dose map with corresponding uncertainty. Results For validation, PARaDIM was used to compute absorbed doses in several clinically and preclinically relevant scenarios, including 1) dosimetry of an 18F‐labeled peptide in humans, which were compared with organ‐level absorbed doses obtained from the widely used OLINDA[2] software and 2) computation of cell‐level absorbed doses in single‐ and multi‐cell geometries, which were compared with results obtained from MIRDcell.[3] For most organs, the agreement of PARaDIM with the output of OLINDA was reasonable (within ± ~20%; see Figure 1), especially considering the differences in phantom geometry used for dose calculation in each software. Agreement of PARaDIM with MIRDcell was similarly good. Conclusion PARaDIM combines the capability for 3D absorbed dose computation via fast Monte Carlo simulation, with the ease of use of the popular programs OLINDA for organ‐ level human/murine absorbed dose calculations and MIRDcell for cell level dosimetry. Monte Carlo simulation using tetrahedral mesh phantoms, which offer significant advantages to traditional mathematical phantoms and voxel phantoms, will be directly applicable for assessment of both organ level and spatially non‐uniform dose deposition applied to populations.
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ACKNOWLEDGEMENTS We gratefully acknowledge the support of the Radiochemistry and Molecular Imaging Probes Core of MSKCC, which was supported in part by NIH grant P30 CA08748. Dr. Carter gratefully acknowledges support from the Ruth L. Kirschstein National Research Service Award postdoctoral fellowship (NIH F32 EB025050).
R EF E RE N C E S 1. Sato T, Iwamoto Y, Hashimoto S, et al (2018) Features of Particle and Heavy Ion Transport code System (PHITS) version 3.02. J Nucl Sci Technol 55:684–690. https://doi.org/10.1080/ 00223131.2017.1419890 2. Stabin MG, Sparks RB, Crowe E (2005) OLINDA/EXM: The Second‐Generation Personal Computer Software for Internal Dose Assessment in Nuclear Medicine. J Nucl Med 46:1023–1027 3. Vaziri B, Wu H, Dhawan AP, et al (2014) MIRD Pamphlet No. 25: MIRDcell V2.0 Software Tool for Dosimetric Analysis of Biologic Response of Multicellular Populations. J Nucl Med 55:1557–1564. https://doi.org/10.2967/jnumed.113.131037
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by acetylation of the remaining dendrimer surface amines and radiolabeling of 99mTc, the SPECT/CT dual mode nanoprobes of tumor apoptosis were constructed. Results The developed multifunctional Au DENPs before and after 99mTc radiolabeling were well characterized. The results demonstrate that the multifunctional Au DENPs display favorable colloidal stability under different conditions, own good cytocompatibility in the given concentration range, and can be effectively labeled by 99mTc with high radiochemical stability. Furthermore, the multifunctional nanoprobes enable the targeted SPECT/CT imaging of apoptotic cancer cells in vitro and tumor apoptosis after doxorubicin treatment in the established subcutaneous tumor model in vivo. Conclusion The designed Duramycin‐functionalized Au DENPs might have the potential to be employed as a nanoplatform for the detection of apoptosis and early tumor response to chemotherapy.
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranos tics )
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( T h e r a p y & Th e r a n o s t i c s )
P-346 | SPECT/CT imaging of chemotherapy‐
P-347 | PET imaging with [11C]NMS‐E973
induced tumor apoptosis using 99mTc‐labeled dendrimer‐entrapped gold nanoparticles Yan Xing
reveals difference between healthy and malignant expressed HSP90 Koen Vermeulen1; Muneer Ahamed2; Guy Bormans1 1
KU Leuven, Belgium; 2 Centre for Advanced Imaging, The University of
Queensland, Australia
Objective Non‐invasive imaging of apoptosis in tumors induced by chemotherapy is of great value in the evaluation of therapeutic efficiency. In this study, we report the synthesis, characterization, and utilization of radionuclide technetium‐99m (99mTc) labeled dendrimer‐entrapped gold nanoparticles (Au DENPs) for targeted SPECT/CT imaging of chemotherapy‐induced tumor apoptosis. Methods Generation five poly (amidoamine) (PAMAM) dendrimers (G5.NH2) were sequentially conjugated with 1,4,7,10‐ tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA), polyethylene glycol (PEG) modified duramycin, PEG monomethyl ether, and fluorescein isothiocyanate (FI) to form the multifunctional dendrimers, which were then utilized as templates to entrap gold nanoparticles. Followed
Objectives Radiosynthesis of [11C]NMS‐E973, a specific HSP90 inhibitor,1,2 was optimized. This tracer was evaluated in B16.F10 melanoma bearing mice. Biodistribution studies were carried out, and μPET studies were conducted on melanoma mice pretreated with two HSP90 inhibitors to assess binding specificity. Ex vivo autoradiography studies were performed on murine B16.F10 melanoma, muscle, and heart tissue sections and compared to in vitro autoradiography on the same tissues. Methods [11C]NMS‐E973 was synthesized through methylation of the corresponding precursor (400‐500 μg) with [11C]MeI in anhydrous DMSO (200‐250 μL) using Cs2CO3 as a base at 100°C for 4 min. The biodistribution was studied in
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B16.F10 melanoma bearing mice at 60 min p.i. (n = 3, 5.5 MBq). Ex vivo autoradiography studies were carried out with [11C]NMS‐E973 on tumour, heart, and muscle sections of B16.F10 melanoma tumour mice. The same slices were used in an in vitro autoradiography experiment where they were incubated with 7.4 kBq of tracer. Dynamic 90‐min μPET scans were conducted on B16.F10 inoculated C57BL/6 mice after injection of 11 MBq of tracer. [11C]NMS‐E973 binding was challenged by pretreatment of the same mice with PU‐H71 or Ganetespib (50 mg/kg). Results Based on prep HPLC integration, methylation yields were 30‐40% with a radiochemical purity of >97% and a molar activity of 90 GBq/μmol. Biodistribution studies indicated low brain uptake, with renal and hepatobiliary excretion. A significant decrease of tumour uptake was observed after blocking with either PU‐H71 or Ganetespib. A decrease of blood radioactivity was also observed after pretreatment with PU‐H71 and Ganetespib. Tumour/Muscle SUV ratios are depicted in Table 1. An intriguing difference in radioactivity distribution and localisation was observed when comparing in vitro and ex vivo autoradiography studies. The tracer was localised at the edges of the tissue sections in in vitro studies, whereas the radioactivity was more uniformly distributed in the ex vivo case. Moreover, muscle tissue radioactivity was clearly lower compared to myocardium and tumour tissue in ex vivo autoradiography, but in vitro, this binding is clearly increased. μPET experiments showed high selective tumour uptake, which could be significantly blocked by pretreatment with PU‐H71 or Ganetespib (SUV0‐90min P ≤ 0.001). Table 1: Tumour/Muscle SUV ratios of biodistribution 60 min p.i. on B16.F10 melanoma inoculated mice pretreated with vehicle, PU‐H71 or Ganetespib. Data presented as mean ± SD.
Tumour/Muscle
60 min p.i. control
PU‐H71
Ganetespib
2.4 ± 0.9
1.2 ± 0.2
1.1 ± 0.2
Conclusions We successfully radiolabelled and evaluated a potential carbon‐11 labelled radiotracer for in vitro and ex vivo visualization of HSP90. Biodistribution studies and μPET experiments in tumour bearing mice indicated specific binding of the tracer in melanoma tumours and in blood of tumour bearing mice. Remarkable differences in vitro vs ex vivo autoradiography were observed suggesting that HSP90 expression may change acutely in dying cells. Taken together, [11C]NMS‐E973 is a promising PET probe to target HSP90 expressing tumours and can be used to quantify occupancy of HSP90‐targeted drugs.
RE FER EN CES 1. Brasca M.G., et al., Bioorg Med Chem 2013, 21, 7047–7063 2. Fogliatto G., et al., Clin Cancer Res 2013, 19, 3520–3532
Po s te r Ca teg o r y : Ra di ol a b e l e d Compounds ‐ O n co l og y ( T h e r a p y & Th e r a n o s t i c s ) P-348 | Second generation of triazolominigastrins: Towards further improvement of tumour‐targeting characteristics of radiopeptidomimetics Nathalie Grob1; Sarah Schmid2; Martin Behe; Roger Schibli1; Thomas Mindt3 1
ETH Zurich, Switzerland; 2 ETH Zurich, Institute of Pharmaceutical
Sciences, Switzerland; 3 Ludwig Boltzmann Institute Applied Diagnostics, Austria
Objectives The cholecystokinin receptor type 2 (CCK2R) is an attractive target for nuclear medicine due to its overexpression by different types of cancer, such as, e.g., medullary thyroid cancer and small cell lung cancer. Many of the CCK2R‐targeting radiopeptides displayed poor metabolic stability resulting in unfavourably low tumour uptake. To improve the resistance against enzymatic degradation, amide bonds in the peptide sequence were systematically replaced by metabolically stable 1,4‐disubstitued 1,2,3‐ triazoles, a method referred to as triazole scan. [1, 2] The initial triazole scan performed with the short CCK2R ligand DOTA[Nle15]‐MG11 (DOTA‐DGlu‐Ala‐Tyr‐Gly‐ Trp‐Nle‐Asp‐Phe‐NH2) generated a library of mono‐ substituted triazolominigastrins (mono‐TZMGs), which presented either higher metabolic resistance or improved receptor affinity in vitro, but never both. [3, 4] Biodistribution studies in mice bearing tumour xenografts confirmed the superior characteristics of the mono‐ TZMGs by an increased tumour uptake. The second generation of TZMGs builds up on these results and probed the possibility of additive or synergistic effects resulting from multiple amide‐to‐triazole modifications per peptide. The most promising candidates were selected for in vivo biodistribution studies in tumour‐bearing mice and the first results will be discussed. Methods A library of multi‐TZMGs based on the sequence of DOTA[Nle15]‐MG11 was prepared following standard solid‐phase peptide synthesis procedures and the Copper(I)‐catalysed azide‐alkyne cycloaddition (CuAAC).
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Amide bonds for multiple triazole modifications were chosen in order to investigate the combination of better affinity and/or stability or both, based on the effects seen in the mono‐TZMGs. The conjugates were labelled with [177Lu]LuCl3 for evaluation of their physiochemical properties in vitro and in vivo. Receptor affinity (IC50) and cell internalisation were determined using a CCK2R‐positive cell line from human medullary thyroid cancer (MZ‐ CRC1). Metabolic stability was measured in human blood plasma, and logD values were determined by the shake‐ flask method in octanol and PBS. Biodistribution in nude mice with tumour xenografts of the MZ‐CRC1 cell line was analysed 4 hours post injection. Results The second generation of TZMGs was successfully synthesised in high yields and purities. The multi‐TZMGs were radiolabelled with [177Lu]LuCl3 in radiochemical yields and purities of >95%. The majority of the tested peptidomimetics confirmed that the triazole modification of more than one amide bond was beneficial for the tumour‐targeting characteristics. The insertion of two triazoles at different positions also led to analogues that showed improvements in both receptor affinity and metabolic stability. The best candidate of the second generation showed a four‐fold cell internalisation after 30 minutes and a four times longer plasma half‐life compared to the all‐amide reference structure (Figure 1). Can-
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didates selected for in vivo studies demonstrated higher and faster cell internalisation and reduced IC50 values. Conclusion Amide‐to‐triazole substitutions were well tolerated in minigastrin analogues and showed that triazole insertions can improve the pharmacokinetic properties of the radiotracer (metabolisation) but also have the potential of a positive impact on the pharmacodynamics with a significantly higher receptor affinity and rate of cell internalisation. Compared to the mono‐TZMGs, which showed either improved stability or affinity, multi‐ TZMGs for the first time demonstrated that both properties could be enhanced at once. ACKNOWLEDGEMENT This work was supported by the Swiss National Science Foundation (Project‐Nr. 200021‐157076 to T. Mindt) RE FER EN CES 1. Valverde IE, Bauman A, Kluba C, Vomstein S, Walter M, Mindt TL. Angew Chem‐Int Edit 2013; 52:8957‐8960. 2. Mascarin A, Valverde IE, Vomstein S, Mindt TL. Bioconjug Chem 2015; 26:2143‐‐2152. 3. Grob NM, Béhé M, Schibli R, Mindt TL. manuscript in preparation. 4. Mindt TL, Béhé M, Schibli R, Grob NM; patent application 2017P20166WO, 2017. Minigastrin derivatives, in particular for use in CCK2 Receptor positive tumour diagnosis and/or treatment.
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Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranostics ) P-349 | Radiolabeling and in vitro evaluation of a TA‐MUC1 specific monoclonal antibody and its corresponding single chain fragment with zirconium‐89, scandium‐44, and lutetium‐ 177: Promising tools for diagnosis and therapy of breast cancer Benedikt Klasen1; Natascha Stergiou2; Euy Sung Moon3; Edgar Schmitt2; Frank Roesch4 1
Institute for Nuclear Chemistry, Johannes Gutenberg‐University Mainz,
Germany; 2 Institute for Immunology, University Medical Center Mainz, Germany; 3 Johannes Gutenberg University Mainz, Institute of Nuclear Chemistry, Germany; 4 Johannes Gutenberg Univ., Germany
Objectives Breast cancer is the most frequently occurring malignancy among women and the second most common tumor disease overall. In 2018, more than 2 million new cases were diagnosed and approximately 627,000 breast cancer‐ related deaths are estimated.[1] Hence, the development of novel, more efficient methods for diagnosis and therapy of this disease is of great medical importance. A promising strategy is the application of antibodies with high specificity towards molecular targets being overexpressed on cancer cells. Due to their molecular weight, full‐size immunoglobulins typically have slow pharmacokinetics and long circulation times. Therefore, the utilization of smaller antibody‐fragments like Fab (fragment antigen binding) or recombinant ScFv (single chain variable fragment) gained increasing attention in current research. Tumor‐associated Mucin1 (TA‐MUC1) is expressed on over 90% of all breast tumors and differs strongly from its physiological form on healthy epithelial cells. The unique monoclonal antibody GGSK‐1/30[2] offers high affinity and specificity towards TA‐MUC1 and in vitro evaluation and preclinical Immuno‐PET application of the corresponding 89Zr‐labeled immunoconjugate [89Zr]Zr‐Df‐Bz‐ NCS‐GGSK‐1/30 showed excellent results. For therapeutic approaches, in this study radiolabeling of intact GGSK‐1/ 30 antibody and its recombinant ScFv with the therapy‐ nuclide lutetium‐177 should be investigated. Additionally, the ScFv should also be radiolabeled with zirconium‐89 and the shorter‐lived PET‐nuclide scandium‐44. Methods The monoclonal antibody GGSK‐1/30 and the corresponding ScFv were functionalized with a tenfold molar excess of
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AAZTA5‐en‐SA resulting in an estimated ratio of bound chelator moieties per protein of 4‐5. For 89Zr‐labeling, the ScFv was analogously coupled to the hexadentate chelator Df‐Bz‐NCS. After purification via size exclusion chromatography (SEC), the resulting immunoconjugates were radiolabeled at room temperature with lutetium‐177, scandium‐44, and zirconium‐89, respectively. The obtained radioconjugates were then purified via SEC, and their complex stability in 0.9 % NaCl‐solution and human serum was analyzed. Results In all cases, the coupling of the appropriate chelator to the different proteins could be confirmed by successful radiolabeling of the resulting conjugates with lutetium‐ 177, scandium‐44, and zirconium‐89. In detail, 177Lu‐labeling resulted in a radiochemical yield of 63.9% after 90 min for AAZTA5‐en‐SA‐GGSK‐1/30 and 80.5% after 30 min for AAZTA5‐en‐SA‐ScFv, respectively. The 89Zr‐labeled Df‐ Bz‐NCS‐ScFv could be obtained with 76.8% RCY after 90 min and 44Sc‐labeling of AAZTA5‐en‐SA‐ScFv resulted in 32.4% RCY. Within radiolabeling experiments of the AAZTA5‐en‐SA‐functionalized proteins, the presence of unbound chelator residues was determined leading to slightly decreased radiochemical yields. This impurity could be completely removed via SEC. After purification, [177Lu]Lu‐ [177Lu]Lu‐AAZTA5‐en‐SA‐GGSK‐1/30, 5 89 AAZTA ‐en‐SA‐ScFv, [ Zr]Zr‐Df‐Bz‐NCS‐ScFv, and [44Sc]Sc‐AAZTA5‐en‐SA‐ScFv were thus obtained with radiochemical purities of >95 %, and apparent specific activities of 4.1, 1.0, 1.0, and 0.6 GBq/μmol, respectively. Complex stability measurements in 0.9% NaCl‐solution indicated >91, >94, and >98 % protein‐bound activity within 7 days for [177Lu]Lu‐AAZTA5‐en‐SA‐GGSK‐1/30, [177Lu]Lu‐AAZTA5‐en‐SA‐ScFv and [89Zr]Zr‐Df‐Bz‐NCS‐ ScFv, respectively. In human serum, the 177Lu‐ and 89Zr‐ labeled ScFv‐conjugates remained stable (>97 %) over a period of 7 days. Conclusions The TA‐MUC1 specific antibody GGSK‐1/30 was successfully radiolabeled with lutetium‐177 using AAZTA5‐en‐ SA coupled to the protein. The resulting radioconjugate [177Lu]Lu‐AAZTA5‐en‐SA‐GGSK‐1/30 offers a high complex stability in NaCl‐solution over 7 days. Hence, it represents a promising tool for therapy of TA‐MUC1 expressing breast cancer. The corresponding single chain variable fragment could be successfully functionalized with AAZTA5‐en‐SA as well as with Df‐Bz‐NCS and radiolabeled with lutetium‐177, scandium‐44, and zirconium‐ 89. Both the 177Lu‐ and 89Zr‐labeled ScFv‐conjugates remained stable in human serum and NaCl‐solution within 7 days. Due to their lower molecular weight, these radioconjugates should provide a significant improvement
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compared to the intact antibody in terms of pharmacokinetics and circulation time. AAZTA5‐en‐ScFv therefore represents a potential radiopharmaceutical for both Immuno‐PET diagnosis and therapy of breast cancer only by changing the radionuclide from scandium‐44 to lutetium‐177. R EF E RE N C E S 1. Ng V. Y., Scharschmidt T. J., Mayerson J. L., Fisher J. L., Anticancer Res 2013, 33, 2597–2604. 2. Palitzsch B., Gaidzik N., Stergiou N., Stahn S., Hartmann S., Gerlitzki B., Teusch N., Flemming P., Schmitt E., Kunz H., Angew Chem Int Ed 2016, 55, 2894–2898
Poster Cate gory: Radiola bele d C o m p o u n d s ‐ O nc o l o g y ( T h e r a p y & Theranos tics ) P-350 | Preclinical evaluation of chemokine receptor 4 (CXCR4) as a theranostic target in high‐risk neuroblastoma Dijie Liu; Michael Schultz; Mengshi Li; Dongyoul Lee; Kimia Nourmahnad; Andrew Bellizzi; M. Sue O'Dorisio University of iowa, United States
Objectives Neuroblastoma (NB) is the most common extracranial solid tumor of childhood accounting for ~8‐10% of all pediatric solid tumors. Over 50% of high‐risk NB patients experience bone marrow and/or liver metastases and relapse with 4‐year overall survival