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Bonnefoy C, Chefdeville E, Tourvieille C, Panossian A, Hanquet G, Leroux F, Toulgoat F, Billard T. Study of Carbamoyl Fluoride: Synthesis, Properties and Applications. Chemistry 2022; 28:e202201589. [PMID: 35639343 DOI: 10.1002/chem.202201589] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 12/14/2022]
Abstract
Carbamoyl fluoride is a fluorinated group that, to this date, remains underexplored, probably due to the lack of data concerning its properties. In this paper, a study of carbamoyl fluoride is presented. Stability studies, in particular under physiological conditions, and lipophilicity measurement were performed. A new easy, safe, inexpensive, and metal-free synthesis method is also described. Finally, a potential use in radiochemistry through a 18 F/19 F isotopic exchange is demonstrated.
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Affiliation(s)
- Clémence Bonnefoy
- Institute of Chemistry and Biochemistry (ICBMS-UMR CNRS 5246), Univ Lyon, CNRS, Université Lyon 1, 1 rue Victor Grignard, 69622, Lyon, France
| | - Emmanuel Chefdeville
- NMR Centre, Univ Lyon, Université Lyon 1, CNRS, 1 rue Victor Grignard, 69622, Lyon, France
| | | | - Armen Panossian
- Université de Strasbourg, Université de Haute-Alsace, CNRS, UMR 7042-LIMA, ECPM, 67000, Strasbourg, France
| | - Gilles Hanquet
- Université de Strasbourg, Université de Haute-Alsace, CNRS, UMR 7042-LIMA, ECPM, 67000, Strasbourg, France
| | - Frédéric Leroux
- Université de Strasbourg, Université de Haute-Alsace, CNRS, UMR 7042-LIMA, ECPM, 67000, Strasbourg, France
| | - Fabien Toulgoat
- Institute of Chemistry and Biochemistry (ICBMS-UMR CNRS 5246), Univ Lyon, CNRS, Université Lyon 1, 1 rue Victor Grignard, 69622, Lyon, France.,CPE, Lyon Campus LyonTech-La Doua, 43 Bd du 11 novembre 1918, 69616, Villeurbanne, France
| | - Thierry Billard
- Institute of Chemistry and Biochemistry (ICBMS-UMR CNRS 5246), Univ Lyon, CNRS, Université Lyon 1, 1 rue Victor Grignard, 69622, Lyon, France.,CERMEP-In vivo imaging Groupement Hospitalier Est, 59 Bd Pinel, 69677, Lyon, France
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2
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Special radionuclide production activities – recent developments at QST and throughout Japan. RADIOCHIM ACTA 2022. [DOI: 10.1515/ract-2021-1124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
National Institutes for Quantum Science and Technology (QST), formerly known as the National Institute of Radiological Sciences (NIRS), has been engaged in work on radiopharmaceutical science using cyclotrons since 1974. Eight pioneering researchers founded the basis of this field of research at NIRS, and to the present, many researchers and technicians have accumulated both scientific and technical achievements, as well as inherited the spirit of research. Besides, in recent years, we have developed production systems with AVF-930 cyclotron for various ‘non-standard’ radioisotopes applied in both diagnosis and therapy. Here, we review the past 50 years of our activities on radioisotope and radiopharmaceutical development, as well as more recent activities.
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Bratteby K, Shalgunov V, Herth MM. Aliphatic 18 F-Radiofluorination: Recent Advances in the Labeling of Base-Sensitive Substrates*. ChemMedChem 2021; 16:2612-2622. [PMID: 34169672 DOI: 10.1002/cmdc.202100303] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Indexed: 12/19/2022]
Abstract
Aliphatic fluorine-18 radiolabeling is the most commonly used method to synthesize tracers for PET-imaging. With an increasing demand for 18 F-radiotracers for clinical applications, new labeling strategies aiming to increase radiochemical yields of established tracers or, more importantly, to enable 18 F-labeling of new scaffolds have been developed. In recent years, increased attention has been focused on the direct aliphatic 18 F-fluorination of base-sensitive substrates in this respect. This minireview gives a concise overview of the recent advances within this field and aims to highlight the advantages and limitations of these methods.
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Affiliation(s)
- Klas Bratteby
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, 2100, Copenhagen, Denmark.,Department of Radiation Physics, Skåne University Hospital, Barngatan 3, 222 42, Lund, Sweden.,Department of Clinical Physiology, Nuclear Medicine & PET Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark
| | - Vladimir Shalgunov
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, 2100, Copenhagen, Denmark
| | - Matthias Manfred Herth
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, 2100, Copenhagen, Denmark.,Department of Clinical Physiology, Nuclear Medicine & PET Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark
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4
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Liu C, Tang J, Xu Y, Cao S, Fang Y, Zhao C, Chen Z. Molar activity of [ 18F]FP-(+)-DTBZ radiopharmaceutical: Determination and its effect on quantitative analysis of VMAT2 autoradiography. J Pharm Biomed Anal 2021; 203:114212. [PMID: 34153939 DOI: 10.1016/j.jpba.2021.114212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 04/24/2021] [Accepted: 06/13/2021] [Indexed: 10/21/2022]
Abstract
[18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]FP-(+)-DTBZ) is a rising positron tracer for imaging vesicular monoamine transporter II (VMAT2) in the central nervous system. The present work was to develop a novel chromatographic method capable of the molar activity (Am) determination of [18F]FP-(+)-DTBZ. As a complement work of the Am measurement, we also investigated the effect of Am on the quantitative analysis of VMAT2 autoradiography with [18F]FP-(+)-DTBZ. The Am determination was performed by high performance liquid chromatography (HPLC) using the non-radioactive standard (FP-(+)-DTBZ) for calibration plot of peak area against concentration. Based on this correlation, the Am of [18F]FP-(+)-DTBZ was calculated and corrected to the end of synthesis. In the quantitative analysis of in vitro VMAT2 autoradiography, the striatum radioactivity uptake together with the uptake ratio of striatum versus cortex reduced along with the decrease of Am and the increase of the FP-(+)-DTBZ content. Therefore, the Am and the corresponding FP-(+)-DTBZ content have a significant effect on the quantitative analysis of VMAT2 autoradiography using [18F]FP-(+)-DTBZ.
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Affiliation(s)
- Chunyi Liu
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China
| | - Jie Tang
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China
| | - Yingjiao Xu
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China; Department of Radiopharmaceuticals, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Shanshan Cao
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China
| | - Yi Fang
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China
| | - Chao Zhao
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China
| | - Zhengping Chen
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, 214063, China.
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5
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Pellico J, Gawne PJ, T M de Rosales R. Radiolabelling of nanomaterials for medical imaging and therapy. Chem Soc Rev 2021; 50:3355-3423. [PMID: 33491714 DOI: 10.1039/d0cs00384k] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nanomaterials offer unique physical, chemical and biological properties of interest for medical imaging and therapy. Over the last two decades, there has been an increasing effort to translate nanomaterial-based medicinal products (so-called nanomedicines) into clinical practice and, although multiple nanoparticle-based formulations are clinically available, there is still a disparity between the number of pre-clinical products and those that reach clinical approval. To facilitate the efficient clinical translation of nanomedicinal-drugs, it is important to study their whole-body biodistribution and pharmacokinetics from the early stages of their development. Integrating this knowledge with that of their therapeutic profile and/or toxicity should provide a powerful combination to efficiently inform nanomedicine trials and allow early selection of the most promising candidates. In this context, radiolabelling nanomaterials allows whole-body and non-invasive in vivo tracking by the sensitive clinical imaging techniques positron emission tomography (PET), and single photon emission computed tomography (SPECT). Furthermore, certain radionuclides with specific nuclear emissions can elicit therapeutic effects by themselves, leading to radionuclide-based therapy. To ensure robust information during the development of nanomaterials for PET/SPECT imaging and/or radionuclide therapy, selection of the most appropriate radiolabelling method and knowledge of its limitations are critical. Different radiolabelling strategies are available depending on the type of material, the radionuclide and/or the final application. In this review we describe the different radiolabelling strategies currently available, with a critical vision over their advantages and disadvantages. The final aim is to review the most relevant and up-to-date knowledge available in this field, and support the efficient clinical translation of future nanomedicinal products for in vivo imaging and/or therapy.
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Affiliation(s)
- Juan Pellico
- School of Biomedical Engineering & Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, UK.
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6
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Wang J, van Dam RM. High-Efficiency Production of Radiopharmaceuticals via Droplet Radiochemistry: A Review of Recent Progress. Mol Imaging 2020; 19:1536012120973099. [PMID: 33296272 PMCID: PMC7731702 DOI: 10.1177/1536012120973099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/02/2020] [Accepted: 10/12/2020] [Indexed: 12/13/2022] Open
Abstract
New platforms are enabling radiochemistry to be carried out in tiny, microliter-scale volumes, and this capability has enormous benefits for the production of radiopharmaceuticals. These droplet-based technologies can achieve comparable or better yields compared to conventional methods, but with vastly reduced reagent consumption, shorter synthesis time, higher molar activity (even for low activity batches), faster purification, and ultra-compact system size. We review here the state of the art of this emerging direction, summarize the radiotracers and prosthetic groups that have been synthesized in droplet format, describe recent achievements in scaling up activity levels, and discuss advantages and limitations and the future outlook of these innovative devices.
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Affiliation(s)
- Jia Wang
- Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA, Los Angeles, CA, USA
| | - R. Michael van Dam
- Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA, Los Angeles, CA, USA
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7
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Yang BY, Telu S, Haskali MB, Morse CL, Pike VW. A Gas Phase Route to [ 18F]fluoroform with Limited Molar Activity Dilution. Sci Rep 2019; 9:14835. [PMID: 31619702 PMCID: PMC6795885 DOI: 10.1038/s41598-019-50747-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/12/2019] [Indexed: 01/03/2023] Open
Abstract
Positron emission tomography (PET) is an important imaging modality for biomedical research and drug development. PET requires biochemically selective radiotracers to realize full potential. Fluorine-18 (t1/2 = 109.8 min) is a major radionuclide for labeling such radiotracers but is only readily available in high activities from cyclotrons as [18F]fluoride ion. [18F]fluoroform has emerged for labeling tracers in trifluoromethyl groups. Prior methods of [18F]fluoroform synthesis used difluoro precursors in solution and led to high dilution with carrier and low molar activity (Am). We explored a new approach for the synthesis of [18F]fluoroform based on the radiosynthesis of [18F]fluoromethane from [18F]fluoride ion and then cobaltIII fluoride mediated gas phase fluorination. We estimate that carrier dilution in this process is limited to about 3-fold and find that moderate to high Am values can be achieved. We show that [18F]fluoroform so produced is highly versatile for rapidly and efficiently labeling various chemotypes that carry trifluoromethyl groups, thereby expanding prospects for developing new PET radiotracers.
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Affiliation(s)
- Bo Yeun Yang
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Mohammad B Haskali
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA.
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8
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Mikolajczak R, van der Meulen NP, Lapi SE. Radiometals for imaging and theranostics, current production, and future perspectives. J Labelled Comp Radiopharm 2019; 62:615-634. [PMID: 31137083 DOI: 10.1002/jlcr.3770] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/10/2019] [Accepted: 05/15/2019] [Indexed: 02/06/2023]
Abstract
The aim of this review is to make the reader familiar with currently available radiometals, their production modes, capacities, and quality concerns related to their medical use, as well as new emerging radiometals and irradiation technologies from the perspective of their diagnostic and theranostic applications. Production methods of 177 Lu serve as an example of various issues related to the production yield, specific activity, radionuclidic and chemical purity, and production economy. Other radiometals that are currently used or explored for potential medical applications, with particular focus on their theranostic value, are discussed. Using radiometals for diagnostic imaging and therapy is on the rise. The high demand for radiometals for medical use prompts investigations towards using alternative irradiation reactions, while using existing nuclear reactors and accelerator facilities. This review discusses these production capacities and what is necessary to cover the growing demand for theranostic nuclides.
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Affiliation(s)
- Renata Mikolajczak
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland
| | | | - Suzanne E Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama
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9
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Bhatt NB, Pandya DN, Rideout-Danner S, Gage HD, Marini FC, Wadas TJ. A comprehensively revised strategy that improves the specific activity and long-term stability of clinically relevant 89Zr-immuno-PET agents. Dalton Trans 2018; 47:13214-13221. [PMID: 30178793 PMCID: PMC6192516 DOI: 10.1039/c8dt01841c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Zirconium-89 is currently being used in numerous clinical trials involving monoclonal antibodies and positron emission tomography. This report describes a revised strategy that reduces preparation time while increasing the specific activity of clinically relevant immuno-PET agents. Additionally, it demonstrates that n-acetyl-l-cysteine acts as a superior radioprotective agent that improves long-term stability without compromising antigen affinity in vivo.
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Affiliation(s)
- Nikunj B Bhatt
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
| | - Darpan N Pandya
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
| | | | - Howard D Gage
- Department of Radiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Frank C Marini
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA. and Wake Forest Institute of Regenerative Medicine, Winston-Salem, NC 27157, USA
| | - Thaddeus J Wadas
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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10
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Savisto N, Bergman J, Aromaa J, Forsback S, Eskola O, Viljanen T, Rajander J, Johansson S, Grigg J, Luthra S, Solin O. Influence of transport line material on the molar activity of cyclotron produced [18F]fluoride. Nucl Med Biol 2018; 64-65:8-15. [DOI: 10.1016/j.nucmedbio.2018.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/28/2018] [Accepted: 06/16/2018] [Indexed: 10/28/2022]
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Performing radiosynthesis in microvolumes to maximize molar activity of tracers for positron emission tomography. Commun Chem 2018; 1. [PMID: 34291178 DOI: 10.1038/s42004-018-0009-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Positron emission tomography (PET) is a molecular diagnostic imaging technology to quantitatively visualize biological processes in vivo. For many applications, including imaging of low tissue density targets (e.g. neuroreceptors), imaging in small animals, and evaluation of novel tracers, the injected PET tracer must be produced with high molar activity to ensure low occupancy of biological targets and avoid pharmacologic effects. Additionally, high molar activity is essential for tracers with lengthy syntheses or tracers transported to distant imaging sites. We show that radiosynthesis of PET tracers in microliter volumes instead of conventional milliliter volumes results in substantially increased molar activity, and we identify the most relevant variables affecting this parameter. Furthermore, using the PET tracer [18F]fallypride, we illustrate that molar activity can have a significant impact on biodistribution. With full automation, microdroplet platforms could provide a means for radiochemists to routinely, conveniently, and safely produce PET tracers with high molar activity.
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12
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Coenen HH, Gee AD, Adam M, Antoni G, Cutler CS, Fujibayashi Y, Jeong JM, Mach RH, Mindt TL, Pike VW, Windhorst AD. Consensus nomenclature rules for radiopharmaceutical chemistry - Setting the record straight. Nucl Med Biol 2017; 55:v-xi. [PMID: 29074076 DOI: 10.1016/j.nucmedbio.2017.09.004] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 09/22/2017] [Indexed: 10/18/2022]
Abstract
Over recent years, within the community of radiopharmaceutical sciences, there has been an increased incidence of incorrect usage of established scientific terms and conventions, and even the emergence of 'self-invented' terms. In order to address these concerns, an international Working Group on 'Nomenclature in Radiopharmaceutical Chemistry and related areas' was established in 2015 to achieve clarification of terms and to generate consensus on the utilisation of a standardised nomenclature pertinent to the field. Upon open consultation, the following consensus guidelines were agreed, which aim to.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Thomas L Mindt
- Ludwig Boltzmann Institute Applied Diagnostics, Vienna, Austria
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13
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Gómez AB, Cortés González MA, Lübcke M, Johansson MJ, Halldin C, Szabó KJ, Schou M. Efficient DBU accelerated synthesis of 18F-labelled trifluoroacetamides. Chem Commun (Camb) 2016; 52:13963-13966. [PMID: 27844069 DOI: 10.1039/c6cc08535k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Nucleophilic 18F-fluorination of bromodifluoromethyl derivatives was performed using [18F]Bu4NF in the presence of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). This novel procedure provided a diverse set of [18F]trifluoroacetamides in good to excellent radiochemical conversions. A mechanism where DBU acts as organomediator in this transformation is proposed.
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Affiliation(s)
- Antonio Bermejo Gómez
- AstraZeneca Personalised Healthcare and Biomarkers, PET Centre at Karolinska Institutet, Karolinska Universitetssjukhuset Solna, R5:02, SE-171 76 Stockholm, Sweden. and Department of Organic Chemistry, Stockholm University, Arrhenius Laboratory, SE-106 91 Stockholm, Sweden and Stockholm Brain Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Miguel A Cortés González
- Department of Organic Chemistry, Stockholm University, Arrhenius Laboratory, SE-106 91 Stockholm, Sweden and Stockholm Brain Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Marvin Lübcke
- Department of Organic Chemistry, Stockholm University, Arrhenius Laboratory, SE-106 91 Stockholm, Sweden and Stockholm Brain Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Magnus J Johansson
- CVMD iMed, Medicinal Chemistry AstraZeneca R&D, Mölndal, SE-431 83, Sweden
| | - Christer Halldin
- Stockholm Brain Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden and Department of Clinical Neuroscience, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Kálmán J Szabó
- Department of Organic Chemistry, Stockholm University, Arrhenius Laboratory, SE-106 91 Stockholm, Sweden and Stockholm Brain Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Magnus Schou
- AstraZeneca Personalised Healthcare and Biomarkers, PET Centre at Karolinska Institutet, Karolinska Universitetssjukhuset Solna, R5:02, SE-171 76 Stockholm, Sweden. and Stockholm Brain Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden and Department of Clinical Neuroscience, Karolinska Institutet, S-17176 Stockholm, Sweden
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14
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Abstract
The goal of individualized and targeted treatment and precision medicine requires the assessment of potential therapeutic targets to direct treatment selection. The biomarkers used to direct precision medicine, often termed companion diagnostics, for highly targeted drugs have thus far been almost entirely based on in vitro assay of biopsy material. Molecular imaging companion diagnostics offer a number of features complementary to those from in vitro assay, including the ability to measure the heterogeneity of each patient's cancer across the entire disease burden and to measure early changes in response to treatment. We discuss the use of molecular imaging methods as companion diagnostics for cancer therapy with the goal of predicting response to targeted therapy and measuring early (pharmacodynamic) response as an indication of whether the treatment has "hit" the target. We also discuss considerations for probe development for molecular imaging companion diagnostics, including both small-molecule probes and larger molecules such as labeled antibodies and related constructs. We then describe two examples where both predictive and pharmacodynamic molecular imaging markers have been tested in humans: endocrine therapy for breast cancer and human epidermal growth factor receptor type 2-targeted therapy. The review closes with a summary of the items needed to move molecular imaging companion diagnostics from early studies into multicenter trials and into the clinic.
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Affiliation(s)
- David A Mankoff
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
| | - Christine E Edmonds
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Michael D Farwell
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Daniel A Pryma
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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15
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Preshlock S, Tredwell M, Gouverneur V. (18)F-Labeling of Arenes and Heteroarenes for Applications in Positron Emission Tomography. Chem Rev 2016; 116:719-66. [PMID: 26751274 DOI: 10.1021/acs.chemrev.5b00493] [Citation(s) in RCA: 477] [Impact Index Per Article: 59.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Diverse radiochemistry is an essential component of nuclear medicine; this includes imaging techniques such as positron emission tomography (PET). As such, PET can track diseases at an early stage of development, help patient care planning through personalized medicine and support drug discovery programs. Fluorine-18 is the most frequently used radioisotope in PET radiopharmaceuticals for both clinical and preclinical research. Its physical and nuclear characteristics (97% β(+) decay, 109.8 min half-life, 635 keV positron energy) and high specific activity make it an attractive nuclide for labeling and molecular imaging. Arenes and heteroarenes are privileged candidates for (18)F-incorporation as they are metabolically robust and therefore widely used by medicinal chemists and radiochemists alike. For many years, the range of (hetero)arenes amenable to (18)F-fluorination was limited by the lack of chemically diverse precursors, and of radiochemical methods allowing (18)F-incorporation in high selectivity and efficiency (radiochemical yield and purity, specific activity, and radio-scalability). The appearance of late-stage fluorination reactions catalyzed by transition metal or small organic molecules (organocatalysis) has encouraged much research on the use of these activation manifolds for (18)F-fluorination. In this piece, we review all of the reactions known to date to install the (18)F substituent and other key (18)F-motifs (e.g., CF3, CHF2, OCF3, SCF3, OCHF2) of medicinal relevance onto (hetero)arenes. The field has changed significantly in the past five years, and the current trend suggests that the radiochemical space available for PET applications will expand rapidly in the near future.
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Affiliation(s)
- Sean Preshlock
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Matthew Tredwell
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Véronique Gouverneur
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
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16
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Pike VW. Considerations in the Development of Reversibly Binding PET Radioligands for Brain Imaging. Curr Med Chem 2016; 23:1818-69. [PMID: 27087244 PMCID: PMC5579844 DOI: 10.2174/0929867323666160418114826] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/04/2016] [Accepted: 04/15/2016] [Indexed: 12/17/2022]
Abstract
The development of reversibly binding radioligands for imaging brain proteins in vivo, such as enzymes, neurotransmitter transporters, receptors and ion channels, with positron emission tomography (PET) is keenly sought for biomedical studies of neuropsychiatric disorders and for drug discovery and development, but is recognized as being highly challenging at the medicinal chemistry level. This article aims to compile and discuss the main considerations to be taken into account by chemists embarking on programs of radioligand development for PET imaging of brain protein targets.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Rm. B3C346A, 10 Center Drive, Bethesda, MD 20892, USA.
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17
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Abstract
The emerging technology of digital microfluidics is opening up the possibility of performing radiochemistry at the microliter scale to produce tracers for positron emission tomography (PET) labeled with fluorine-18 or other isotopes. Working at this volume scale not only reduces reagent costs but also improves specific activity (SA) by reducing contamination by the stable isotope. This technology could provide a practical means to routinely prepare high-SA tracers for applications such as neuroimaging and could make it possible to routinely achieve high SA using synthesis strategies such as isotopic exchange. Reagent droplets are controlled electronically, providing high reliability, a compact control system, and flexibility for diverse syntheses with a single-chip design. The compact size may enable the development of a self-shielded synthesizer that does not require a hot cell. This article reviews the progress of this technology and its application to the synthesis of PET tracers.
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Affiliation(s)
- Pei Yuin Keng
- Crump Institute for Molecular Imaging and Department of Molecular & Medical Pharmacology University of California, Los Angeles
| | - R. Michael van Dam
- Crump Institute for Molecular Imaging and Department of Molecular & Medical Pharmacology University of California, Los Angeles
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18
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Szelecsényi F, Steyn GF, Kovács Z. On the formation of non-radioactive copper during the production of 64Cu via proton and deuteron-induced nuclear reactions on enriched 64Ni targets. J Radioanal Nucl Chem 2015. [DOI: 10.1007/s10967-015-4342-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Khotavivattana T, Verhoog S, Tredwell M, Pfeifer L, Calderwood S, Wheelhouse K, Lee Collier T, Gouverneur V. (18)F-Labeling of Aryl-SCF3, -OCF3 and -OCHF2 with [(18)F]Fluoride. Angew Chem Int Ed Engl 2015; 54:9991-5. [PMID: 26140357 DOI: 10.1002/anie.201504665] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 12/13/2022]
Abstract
We report that halogenophilic silver(I) triflate permits halogen exchange (halex) nucleophilic (18)F-fluorination of aryl-OCHFCl, -OCF2Br and -SCF2Br precursors under mild conditions. This Ag(I)-mediated process allows for the first time access to a range of (18)F-labeled aryl-OCHF2, -OCF3 and -SCF3 derivatives, inclusive of [(18)F]riluzole. The (18)F-labeling of these medicinally important motifs expands the radiochemical space available for PET applications.
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Affiliation(s)
| | - Stefan Verhoog
- University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA (UK)
| | - Matthew Tredwell
- University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA (UK)
| | - Lukas Pfeifer
- University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA (UK)
| | - Samuel Calderwood
- University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA (UK)
| | - Katherine Wheelhouse
- Medicines Discovery & Development, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2NY (UK)
| | | | - Véronique Gouverneur
- University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA (UK).
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Gao M, Wang M, Zheng QH. Fully automated synthesis of [18F]T807, a PET tau tracer for Alzheimer’s disease. Bioorg Med Chem Lett 2015; 25:2953-7. [DOI: 10.1016/j.bmcl.2015.05.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 05/12/2015] [Accepted: 05/13/2015] [Indexed: 01/14/2023]
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21
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Khotavivattana T, Verhoog S, Tredwell M, Pfeifer L, Calderwood S, Wheelhouse K, Lee Collier T, Gouverneur V. 18F-Labeling of Aryl-SCF3, -OCF3and -OCHF2with [18F]Fluoride. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201504665] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Shea C, Alexoff DL, Kim D, Hoque R, Schueller MJ, Fowler JS, Qu W. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide. Appl Radiat Isot 2015; 102:48-54. [PMID: 25980658 DOI: 10.1016/j.apradiso.2015.04.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 03/25/2015] [Accepted: 04/24/2015] [Indexed: 11/26/2022]
Abstract
In this research, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([(11)C]CN¯) produced by our in-house built automated [(11)C]HCN production system and to identify the major sources of (12)C-cyanide ((12)CN¯). The [(11)C]CN¯ is produced from [(11)C]CO2, which is generated by the (14)N(p,α)(11)C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [(11)C]HCN production system were isolated in order to determine their relative contributions to (12)CN¯ mass. It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33µA for 1 and 10min) did not contribute significantly to the mass. Additionally, we compared the SA of our [(11)C]HCN precursor determined using the ISE to the SA of our current [(11)C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose.
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Affiliation(s)
- Colleen Shea
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 901, Upton, NY 11973, USA.
| | - David L Alexoff
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 555, Upton, NY 11973, USA.
| | - Dohyun Kim
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 555, Upton, NY 11973, USA.
| | - Ruma Hoque
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 901, Upton, NY 11973, USA.
| | - Michael J Schueller
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 901, Upton, NY 11973, USA.
| | - Joanna S Fowler
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 555, Upton, NY 11973, USA.
| | - Wenchao Qu
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Building 555, Upton, NY 11973, USA.
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Investigation of SN2 [11C]cyanation for base-sensitive substrates: an improved radiosynthesis of L-[5-11C]-glutamine. Amino Acids 2014; 47:525-33. [PMID: 25488428 DOI: 10.1007/s00726-014-1883-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/21/2014] [Indexed: 10/24/2022]
Abstract
Carbon-11 (β(+) emitter, t1/2 = 20.4 min) radiolabeled L-glutamine is a potentially useful molecular imaging agent that can be utilized with positron emission tomography for both human oncological diagnosis and plant imaging research. Based upon a previously reported [(11)C]cyanide end-capping labeling method, a systematic investigation of nucleophilic cyanation reactions and acidic hydrolysis reaction parameters, including base, metal ion source, phase transfer catalyst, solvent, reaction temperature and reaction time, was conducted. The result was a milder, more reliable, two-step method which provides L-[5-(11)C]-glutamine with a radiochemical yield of 63.8 ± 8.7% (range from 51 to 74%, n = 10) with >90% radiochemical purity and >90 % enantiomeric purity. The total synthesis time was 40-50 min from the end of bombardment. In addition, an Fmoc derivatization method was developed to measure the specific activity of this radiotracer.
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24
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Gao M, Gao AC, Wang M, Zheng QH. Synthesis of carbon-11-labeled aminoalkylindole derivatives as new candidates of cannabinoid receptor radioligands for PET imaging of alcohol abuse. Bioorg Med Chem Lett 2014; 24:5581-5586. [DOI: 10.1016/j.bmcl.2014.10.097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 11/30/2022]
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25
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Facile purification and click labeling with 2-[ 18F]fluoroethyl azide using solid phase extraction cartridges. Tetrahedron Lett 2014; 56:952-954. [PMID: 26989269 DOI: 10.1016/j.tetlet.2014.10.126] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A facile method was developed to purify 2-[18F]fluoroethyl azide ([18F]FEA) using a C18 cartridge and an Oasis® HLB cartridge in series, in which [18F]FEA was exclusively trapped on the HLB cartridge. [18F]FEA can be eluted for reactions in solution; alternatively click labeling can be carried out on the HLB cartridge itself by loading an alkyne substrate and copper (I) catalyst dissolved in DMF onto the cartridge. This solid phase extraction methodology for purification and click labeling with [18F]FEA, either in solution or on the cartridge, is safe, simple, reproducible in high yield, and compatible with automated synthesis of 18F-labeled PET tracers.
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26
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Wang M, Gao M, Zheng QH. The first radiosynthesis of [ 11 C]AZD8931 as a new potential PET agent for imaging of EGFR, HER2 and HER3 signaling. Bioorg Med Chem Lett 2014; 24:4455-4459. [DOI: 10.1016/j.bmcl.2014.07.092] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 11/26/2022]
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27
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Wang M, Gao M, Zheng QH. Synthesis of carbon-11-labeled 4-(phenylamino)-pyrrolo[2,1-f][1,2,4]triazine derivatives as new potential PET tracers for imaging of p38α mitogen-activated protein kinase. Bioorg Med Chem Lett 2014; 24:3700-5. [PMID: 25065491 DOI: 10.1016/j.bmcl.2014.07.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 12/30/2022]
Abstract
The reference standards methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10b) and corresponding precursors 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11b) were synthesized from methyl crotonate and 3-amino-4-methylbenzoic acid in multiple steps with moderate to excellent yields. The target tracer [(11)C]methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([(11)C]10a) and [(11)C]methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([(11)C]10b) were prepared from their corresponding precursors with [(11)C]CH3OTf under basic condition through O-[(11)C]methylation and isolated by a simplified solid-phase extraction (SPE) method in 50-60% radiochemical yields at end of bombardment (EOB) with 185-555 GBq/μmol specific activity at end of synthesis (EOS).
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Affiliation(s)
- Min Wang
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 1345 West 16th Street, Room 202, Indianapolis, IN 46202, USA
| | - Mingzhang Gao
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 1345 West 16th Street, Room 202, Indianapolis, IN 46202, USA
| | - Qi-Huang Zheng
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 1345 West 16th Street, Room 202, Indianapolis, IN 46202, USA.
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28
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Synthesis of a new fluorine-18-labeled bexarotene analogue for PET imaging of retinoid X receptor. Bioorg Med Chem Lett 2014; 24:1742-7. [DOI: 10.1016/j.bmcl.2014.02.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 02/10/2014] [Accepted: 02/13/2014] [Indexed: 11/20/2022]
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29
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Zhou D, Lin M, Yasui N, Al-Qahtani MH, Dence CS, Schwarz S, Katzenellenbogen JA. Optimization of the preparation of fluorine-18-labeled steroid receptor ligands 16alpha-[18F]fluoroestradiol (FES), [18F]fluoro furanyl norprogesterone (FFNP), and 16beta-[18F]fluoro-5alpha-dihydrotestosterone (FDHT) as radiopharmaceuticals. J Labelled Comp Radiopharm 2014; 57:371-7. [PMID: 24861984 DOI: 10.1002/jlcr.3191] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/20/2014] [Accepted: 01/23/2014] [Indexed: 12/24/2022]
Abstract
Fluorine-18-labeled steroid receptor tracers, 16α-[(18)F]fluoroestradiol (FES), [(18)F]fluoro furanyl norprogesterone (FFNP), and 16β-[(18)F]fluoro-5α-dihydrotestosterone (FDHT), are important imaging tools for studies of breast and prostate cancers using positron emission tomography (PET). The automated production of these ligands with high specific activity (SA) as radiopharmaceuticals requires modification and optimization of the currently reported methods. [(18)F]FES with high SA was synthesized in over 60% radiochemical yield (RCY) at the end of synthesis (EOS) using a small amount of precursor (1) (as low as 0.3 mg) and 1 M H2SO4 for deprotection of the intermediate (2). [(18)F]FFNP was synthesized in up to 77% RCY at EOS using the triflate precursor (4) at room temperature or in 25% RCY using the mesylate precursor (6) at 65°C. Both methods are highly reproducible and afford high SA. [(18)F]FDHT was synthesized by radiofluoride incorporation at room temperature, reduction with NaBH4 , and deprotection with HCl/acetone, giving [(18)F]FDHT in up to 75% yield (RCY). All of these methods can be easily translated to automated production. The information provided here will aid in the development of automated production of these steroid receptor tracers with high or improved yields, optimal SA, and ease of processing for research and clinical use.
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Affiliation(s)
- Dong Zhou
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis, MO, 63110, USA
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30
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Concise and high-yield synthesis of T808 and T808P for radiosynthesis of [18F]-T808, a PET tau tracer for Alzheimer’s disease. Bioorg Med Chem Lett 2014; 24:254-7. [DOI: 10.1016/j.bmcl.2013.11.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 11/06/2013] [Accepted: 11/11/2013] [Indexed: 11/20/2022]
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31
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Wang M, Gao M, Zheng QH. A high-yield route to synthesize the P-glycoprotein radioligand [11C]N-desmethyl-loperamide and its parent radioligand [11C]loperamide. Bioorg Med Chem Lett 2013; 23:5259-63. [DOI: 10.1016/j.bmcl.2013.08.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 07/26/2013] [Accepted: 08/05/2013] [Indexed: 11/26/2022]
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32
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Huiban M, Tredwell M, Mizuta S, Wan Z, Zhang X, Collier TL, Gouverneur V, Passchier J. A broadly applicable [18F]trifluoromethylation of aryl and heteroaryl iodides for PET imaging. Nat Chem 2013; 5:941-4. [DOI: 10.1038/nchem.1756] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 08/12/2013] [Indexed: 12/24/2022]
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