1
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Chavan LN, Voll R, Sanchez MM, Nye JA, Goodman MM. Concise and Scalable Radiosynthesis of (+)-[ 18F]MDL100907 as a Serotonin 5-HT 2A Receptor Antagonist for PET. ACS Chem Neurosci 2023; 14:3694-3703. [PMID: 37748194 PMCID: PMC10557077 DOI: 10.1021/acschemneuro.3c00382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/23/2023] [Indexed: 09/27/2023] Open
Abstract
5-Hydroxytryptamine (5-HT2A) receptors play an important role in several psychiatric disorders. In order to investigate the serotonin (5-HT) receptor in vivo, reliable syntheses are required for positron emission tomography (PET) 5-HT radioligands. Owing to the excellent in vivo properties of [18F]MDL100907 for PET, there has been great interest to develop a novel synthetic route for [18F]MDL100907. Here, we report a highly efficient, scalable, and expedient synthesis for [18F]MDL100907. The radiofluorination was performed on a 18F-labeling boron pinacol ester precursor, which is synthesized using the Liebeskind-Srogl cross-coupling reaction as a key step. Our method is practically more suitable to employ late-stage Cu-mediated radiofluorination and facilitate the production of the [18F]MDL100907 radioligand in excellent decay-corrected RCY of 32 ± 10% (n = 7) within 60 min. We prepared [18F]MDL100907 in high molar activity (2.1 Ci/μmol) and compared it to [11C]MDL100907 in the brain of a nonhuman primate.
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Affiliation(s)
- Lahu N. Chavan
- Department
of Radiology and Imaging Science, Emory
University School of Medicine, Atlanta, Georgia 30329, United States
| | - Ronald Voll
- Department
of Radiology and Imaging Science, Emory
University School of Medicine, Atlanta, Georgia 30329, United States
- Department
of Psychiatry and Behavioral Sciences, Emory National Primate Center, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Mar M. Sanchez
- Department
of Psychiatry and Behavioral Sciences, Emory National Primate Center, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Jonathon A. Nye
- Department
of Radiology and Imaging Science, Emory
University School of Medicine, Atlanta, Georgia 30329, United States
- Department
of Psychiatry and Behavioral Sciences, Emory National Primate Center, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Mark M. Goodman
- Department
of Radiology and Imaging Science, Emory
University School of Medicine, Atlanta, Georgia 30329, United States
- Department
of Psychiatry and Behavioral Sciences, Emory National Primate Center, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Department
of Radiology and Imaging Sciences Wesley
Woods Health Center, 1841 Clifton Rd. NE, 2nd Floor, Atlanta, Georgia 30329, United States
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2
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Fu H, Rong J, Chen Z, Zhou J, Collier T, Liang SH. Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors. J Med Chem 2022; 65:10755-10808. [PMID: 35939391 DOI: 10.1021/acs.jmedchem.2c00633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.
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Affiliation(s)
- Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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3
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Rosenberg AJ, Cheung Y, Liu F, Peterson TE, Silverman J, Considine CM, Claassen DO. Automated Synthesis of
(R)
‐[
18
F F]MH.MZ on the iPhase Flexlab Reaction Platform. J Labelled Comp Radiopharm 2022; 65:223-229. [DOI: 10.1002/jlcr.3975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/23/2022] [Accepted: 04/26/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Adam J. Rosenberg
- Vanderbilt University Institute for Imaging Science Vanderbilt University Medical Center Nashville Tennessee USA
- Department of Radiology and Radiological Sciences Vanderbilt University Medical Center Nashville Tennessee USA
| | - Yiu‐Yin Cheung
- Vanderbilt University Institute for Imaging Science Vanderbilt University Medical Center Nashville Tennessee USA
| | - Fei Liu
- Vanderbilt University Institute for Imaging Science Vanderbilt University Medical Center Nashville Tennessee USA
| | - Todd E. Peterson
- Vanderbilt University Institute for Imaging Science Vanderbilt University Medical Center Nashville Tennessee USA
- Department of Radiology and Radiological Sciences Vanderbilt University Medical Center Nashville Tennessee USA
| | - James Silverman
- Department of Neurology Vanderbilt University Medical Center Nashville TN USA
| | - Ciaran M. Considine
- Department of Neurology Vanderbilt University Medical Center Nashville TN USA
| | - Daniel O. Claassen
- Department of Neurology Vanderbilt University Medical Center Nashville TN USA
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4
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Willmann M, Hegger J, Neumaier B, Ermert J. Radiosynthesis and Biological Evaluation of [ 18F]R91150, a Selective 5-HT 2A Receptor Antagonist for PET-Imaging. ACS Med Chem Lett 2021; 12:738-744. [PMID: 34055220 DOI: 10.1021/acsmedchemlett.0c00658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/30/2021] [Indexed: 12/21/2022] Open
Abstract
Serotonergic 5-HT2A receptors in cortical and forebrain regions are an important substrate for the neuromodulatory actions of serotonin in the brain. They have been implicated in the etiology of many neuropsychiatric disorders and serve as a target for antipsychotic, antidepressant, and anxiolytic drugs. Positron emission tomography imaging using suitable radioligands can be applied for in vivo quantification of receptor densities and receptor occupancy for therapy evaluation. Recently, the radiosynthesis of the selective 5-HT2AR antagonist [18F]R91150 was reported. However, the six-step radiosynthesis is cumbersome and time-consuming with low radiochemical yields (RCYs) of <5%. In this work, [18F]R91150 was prepared using late-stage Cu-mediated radiofluorination to simplify its synthesis. The detailed protocol enabled us to obtain RCYs of 14 ± 1%, and the total synthesis time was reduced to 60 min. In addition, autoradiographic studies with [18F]R91150 in rat brain slices revealed the typical uptake pattern of 5-HT2A receptor ligands.
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Affiliation(s)
- Michael Willmann
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
| | - Julian Hegger
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
- Uniklinik Köln, Institute of Radiochemistry and Experimental Molecular Imaging, 50937 Köln, Germany
| | - Johannes Ermert
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
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5
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Klenner MA, Pascali G, Fraser BH, Darwish TA. Kinetic isotope effects and synthetic strategies for deuterated carbon-11 and fluorine-18 labelled PET radiopharmaceuticals. Nucl Med Biol 2021; 96-97:112-147. [PMID: 33892374 DOI: 10.1016/j.nucmedbio.2021.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 11/22/2022]
Abstract
The deuterium labelling of pharmaceuticals is a useful strategy for altering pharmacokinetic properties, particularly for improving metabolic resistance. The pharmacological effects of such metabolites are often assumed to be negligible during standard drug discovery and are factored in later at the clinical phases of development, where the risks and benefits of the treatment and side-effects can be wholly assessed. This paradigm does not translate to the discovery of radiopharmaceuticals, however, as the confounding effects of radiometabolites can inevitably show in preliminary positron emission tomography (PET) scans and thus complicate interpretation. Consequently, the formation of radiometabolites is crucial to take into consideration, compared to non-radioactive metabolites, and the application of deuterium labelling is a particularly attractive approach to minimise radiometabolite formation. Herein, we provide a comprehensive overview of the deuterated carbon-11 and fluorine-18 radiopharmaceuticals employed in PET imaging experiments. Specifically, we explore six categories of deuterated radiopharmaceuticals used to investigate the activities of monoamine oxygenase (MAO), choline, translocator protein (TSPO), vesicular monoamine transporter 2 (VMAT2), neurotransmission and the diagnosis of Alzheimer's disease; from which we derive four prominent deuteration strategies giving rise to a kinetic isotope effect (KIE) for reducing the rate of metabolism. Synthetic approaches for over thirty of these deuterated radiopharmaceuticals are discussed from the perspective of deuterium and radioisotope incorporation, alongside an evaluation of the deuterium labelling and radiolabelling efficacies across these independent studies. Clinical and manufacturing implications are also discussed to provide a more comprehensive overview of how deuterated radiopharmaceuticals may be introduced to routine practice.
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Affiliation(s)
- Mitchell A Klenner
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia; Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, NSW 2170, Australia.
| | - Giancarlo Pascali
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia; Department of Nuclear Medicine and PET, Prince of Wales Hospital, Randwick, NSW 2031, Australia; School of Chemistry, University of New South Wales (UNSW), Kensington, NSW 2052, Australia
| | - Benjamin H Fraser
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Tamim A Darwish
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
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6
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Baeyer-Villiger oxidation tuned to chemoselective conversion of non-activated [18
F]fluorobenzaldehydes to [18
F]fluorophenols. J Labelled Comp Radiopharm 2019; 62:380-392. [DOI: 10.1002/jlcr.3740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/12/2019] [Accepted: 04/18/2019] [Indexed: 12/14/2022]
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7
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Zhang X, Dunlow R, Blackman BN, Swenson RE. Optimization of 18 F-syntheses using 19 F-reagents at tracer-level concentrations and liquid chromatography/tandem mass spectrometry analysis: Improved synthesis of [ 18 F]MDL100907. J Labelled Comp Radiopharm 2018; 61:427-437. [PMID: 29336065 DOI: 10.1002/jlcr.3606] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 12/13/2017] [Accepted: 01/05/2018] [Indexed: 12/19/2022]
Abstract
Traditional radiosynthetic optimization faces the challenges of high radiation exposure, cost, and inability to perform serial reactions due to tracer decay. To accelerate tracer development, we have developed a strategy to simulate radioactive 18 F-syntheses by using tracer-level (nanomolar) non-radioactive 19 F-reagents and LC-MS/MS analysis. The methodology was validated with fallypride synthesis under tracer-level 19 F-conditions, which showed reproducible and comparable results with radiosynthesis, and proved the feasibility of this process. Using this approach, the synthesis of [18 F]MDL100907 was optimized under 19 F-conditions with greatly improved yield. The best conditions were successfully transferred to radiosynthesis. A radiochemical yield of 19% to 22% was achieved with the radiochemical purity >99% and the molar activity 38.8 to 53.6 GBq/ μmol (n = 3). The tracer-level 19 F-approach provides a high-throughput and cost-effective process to optimize radiosynthesis with reduced radiation exposure. This new method allows medicinal and synthetic chemists to optimize radiolabeling conditions without the need to use radioactivity.
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Affiliation(s)
- Xiang Zhang
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Ryan Dunlow
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Burchelle N Blackman
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Rolf E Swenson
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
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8
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Edgar FG, Hansen HD, Leth-Petersen S, Ettrup A, Kristensen JL, Knudsen GM, Herth MM. Synthesis, radiofluorination, and preliminary evaluation of the potential 5-HT 2A receptor agonists [ 18 F]Cimbi-92 and [ 18 F]Cimbi-150. J Labelled Comp Radiopharm 2017; 60:586-591. [PMID: 28856700 DOI: 10.1002/jlcr.3557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/22/2017] [Accepted: 08/23/2017] [Indexed: 12/25/2022]
Abstract
An agonist PET tracer is of key interest for the imaging of the 5-HT2A receptor, as exemplified by the previously reported success of [11 C]Cimbi-36. Fluorine-18 holds several advantages over carbon-11, making it the radionuclide of choice for clinical purposes. In this respect, an 18 F-labelled agonist 5-HT2A receptor (5-HT2A R) tracer is highly sought after. Herein, we report a 2-step, 1-pot labelling methodology of 2 tracer candidates. Both ligands display high in vitro affinities for the 5-HT2A R. The compounds were synthesised from easily accessible labelling precursors, and radiolabelled in acceptable radiochemical yields, sufficient for in vivo studies in domestic pigs. PET images partially conformed to the expected brain distribution of the 5-HT2A R; a notable exception however being significant uptake in the striatum and thalamus. Additionally, a within-scan displacement challenge with a 5-HT2A R antagonist was unsuccessful, indicating that the tracers cannot be considered optimal for neuroimaging of the 5-HT2A R.
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Affiliation(s)
- Fraser Graeme Edgar
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Hanne D Hansen
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen, Denmark
| | | | - Anders Ettrup
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen, Denmark
| | - Jesper L Kristensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Gitte M Knudsen
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen, Denmark
- University of Copenhagen, Copenhagen, Denmark
| | - Matthias M Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen, Denmark
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen, Denmark
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9
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Mossine AV, Brooks AF, Ichiishi N, Makaravage KJ, Sanford MS, Scott PJH. Development of Customized [ 18F]Fluoride Elution Techniques for the Enhancement of Copper-Mediated Late-Stage Radiofluorination. Sci Rep 2017; 7:233. [PMID: 28331174 PMCID: PMC5427906 DOI: 10.1038/s41598-017-00110-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 02/07/2017] [Indexed: 11/10/2022] Open
Abstract
In a relatively short period of time, transition metal-mediated radiofluorination reactions have changed the PET radiochemistry landscape. These reactions have enabled the radiofluorination of a wide range of substrates, facilitating access to radiopharmaceuticals that were challenging to synthesize using traditional fluorine-18 radiochemistry. However, the process of adapting these new reactions for automated radiopharmaceutical production has revealed limitations in fitting them into the confines of traditional radiochemistry systems. In particular, the presence of bases (e.g. K2CO3) and/or phase transfer catalysts (PTC) (e.g. kryptofix 2.2.2) associated with fluorine-18 preparation has been found to be detrimental to reaction yields. We hypothesized that these limitations could be addressed through the development of alternate techniques for preparing [18F]fluoride. This approach also opens the possibility that an eluent can be individually tailored to meet the specific needs of a metal-catalyzed reaction of interest. In this communication, we demonstrate that various solutions of copper salts, bases, and ancillary ligands can be utilized to elute [18F]fluoride from ion exchange cartridges. The new procedures are effective for fluorine-18 radiochemistry and, as proof of concept, have been used to optimize an otherwise base-sensitive copper-mediated radiofluorination reaction.
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Affiliation(s)
- Andrew V Mossine
- Department of Radiology, University of Michigan Medical School, 1301 Catherine St., Ann Arbor, MI, 48109, USA
| | - Allen F Brooks
- Department of Radiology, University of Michigan Medical School, 1301 Catherine St., Ann Arbor, MI, 48109, USA
| | - Naoko Ichiishi
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA
| | - Katarina J Makaravage
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA.
| | - Peter J H Scott
- Department of Radiology, University of Michigan Medical School, 1301 Catherine St., Ann Arbor, MI, 48109, USA.
- Interdepartmental Program in Medicinal Chemistry, University of Michigan, 428 Church St., Ann Arbor, MI, 48109, USA.
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10
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Mc Mahon B, Andersen SB, Madsen MK, Hjordt LV, Hageman I, Dam H, Svarer C, da Cunha-Bang S, Baaré W, Madsen J, Hasholt L, Holst K, Frokjaer VG, Knudsen GM. Seasonal difference in brain serotonin transporter binding predicts symptom severity in patients with seasonal affective disorder. Brain 2016; 139:1605-14. [DOI: 10.1093/brain/aww043] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/28/2016] [Indexed: 11/14/2022] Open
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11
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Herth MM, Knudsen GM. Current radiosynthesis strategies for 5-HT2Areceptor PET tracers. J Labelled Comp Radiopharm 2015; 58:265-73. [DOI: 10.1002/jlcr.3288] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Matthias M. Herth
- Center for Integrated Molecular Brain Imaging; Rigshospitalet and University of Copenhagen; Blegdamsvej 9 Copenhagen DK-2100 Denmark
- Department of Drug Design and Pharmacology; University of Copenhagen; Jagtvej 160 Copenhagen DK-2100 Denmark
| | - Gitte M. Knudsen
- Center for Integrated Molecular Brain Imaging; Rigshospitalet and University of Copenhagen; Blegdamsvej 9 Copenhagen DK-2100 Denmark
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12
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Brooks AF, Topczewski JJ, Ichiishi N, Sanford MS, Scott PJH. Late-stage [ 18F]Fluorination: New Solutions to Old Problems. Chem Sci 2014; 5:4545-4553. [PMID: 25379166 PMCID: PMC4217215 DOI: 10.1039/c4sc02099e] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The last 2-3 years have seen numerous relationships develop between organometallic chemists, fluorine chemists and PET Centers around the world. These collaborations have led to the development of many new strategies for the late-stage introduction of fluorine-18 into complex bioactive molecules. In this perspective we highlight recent developments and key milestones since 2011.
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Affiliation(s)
- Allen F. Brooks
- Department of Radiology, The University of Michigan Medical School Ann Arbor MI, USA
| | | | - Naoko Ichiishi
- Department of Chemistry, The University of Michigan, Ann Arbor MI, USA
| | | | - Peter J. H. Scott
- Department of Radiology, The University of Michigan Medical School Ann Arbor MI, USA
- The Interdepartmental Program in Medicinal Chemistry The University of Michigan, Ann Arbor MI, USA
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13
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Ren H, Wey HY, Strebl M, Neelamegam R, Ritter T, Hooker JM. Synthesis and imaging validation of [¹⁸F]MDL100907 enabled by Ni-mediated fluorination. ACS Chem Neurosci 2014; 5:611-5. [PMID: 24845956 DOI: 10.1021/cn500078e] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Several voids exist in reliable positron emission tomography (PET) radioligands for quantification of the serotonin (5HT) receptor system. Even in cases where 5HT radiotracers exist, challenges remain that have limited the utility of 5HT imaging in clinical research. Herein we address an unmet need in 5HT2a imaging using innovative chemistry. We report a scalable and robust synthesis of [(18)F]MDL100907, which was enabled by a Ni-mediated oxidative fluorination using [(18)F]fluoride. This first demonstration of a Ni-mediated fluorination used for PET imaging required development of a new reaction strategy that ultimately provided high specific activity [(18)F]MDL100907. Using the new synthetic strategy and optimized procedure, [(18)F]MDL100907 was evaluated against [(11)C]MDL100907 for reliability to quantify 5HT₂a in the nonhuman primate brain and was found to be superior based on a single scan analysis using the same nonhuman primate. The use of this new 5HT₂a radiotracer will afford clinical neuroscience research the ability to distinguish 5HT₂a receptor abnormalities binding between healthy subjects and patients even when group differences are small.
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Affiliation(s)
- Hong Ren
- Athinoula A. Martinos
Center for Biomedical Imaging, Massachusetts General Hospital and
Harvard Medical School, 13th Street, Charlestown, Massachusetts 02129, United States
- Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Hsiao-Ying Wey
- Athinoula A. Martinos
Center for Biomedical Imaging, Massachusetts General Hospital and
Harvard Medical School, 13th Street, Charlestown, Massachusetts 02129, United States
| | - Martin Strebl
- Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Ramesh Neelamegam
- Athinoula A. Martinos
Center for Biomedical Imaging, Massachusetts General Hospital and
Harvard Medical School, 13th Street, Charlestown, Massachusetts 02129, United States
| | - Tobias Ritter
- Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Jacob M. Hooker
- Athinoula A. Martinos
Center for Biomedical Imaging, Massachusetts General Hospital and
Harvard Medical School, 13th Street, Charlestown, Massachusetts 02129, United States
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14
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Direct radiofluorination of [18F]MH.MZ for 5-HT2A receptor molecular imaging with PET. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.2947] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Labas R, Gilbert G, Nicole O, Dhilly M, Abbas A, Tirel O, Buisson A, Henry J, Barré L, Debruyne D, Sobrio F. Synthesis, evaluation and metabolic studies of radiotracers containing a 4-(4-[18F]-fluorobenzyl)piperidin-1-yl moiety for the PET imaging of NR2B NMDA receptors. Eur J Med Chem 2011; 46:2295-309. [DOI: 10.1016/j.ejmech.2011.03.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/25/2011] [Accepted: 03/07/2011] [Indexed: 11/25/2022]
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16
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Synthesis, radiofluorination and first evaluation of [18F]fluorophenylsulfonyl- and [18F]fluorophenylsulfinyl-piperidines as serotonin 5-HT2A receptor antagonists for PET. Nucl Med Biol 2010; 37:605-14. [PMID: 20610165 DOI: 10.1016/j.nucmedbio.2010.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 02/04/2010] [Accepted: 03/08/2010] [Indexed: 11/23/2022]
Abstract
In psychiatric disorders, 5-HT(2A) receptors play an important role. In order to study these receptors in vivo by positron emission tomography (PET), there is an increasing interest for subtype selective and high affinity radioligands. Up to now, no optimal radiotracer is available. Thus, 1-(2,4-difluorophenethyl)-4-(4-fluorophenylsulfonyl)piperidine (9), possessing high affinity and sufficient subtype selectivity for 5-HT(2A) receptors, and 1-(2,4-difluorophenethyl)-4-(4-fluorophenylsulfinyl)piperidine (15) have been (18)F-labelled by a nucleophilic one-step reaction. Both radiotracers could be prepared and isolated within 45 min, [(18)F]9 in a radiochemical yield (RCY) of 34.5+/-8% and [(18)F]15 of 9.5+/-2.5%. The K(i) values of 9 and 15 at 5-HT(2A) receptors towards [(3)H]ketanserin were determined to be 1.9+/-0.6 and 198+/-8 nM, respectively. Autoradiography with [(18)F]9 and [(18)F]15 on rat brain sections showed a very high nonspecific binding of >80% for [(18)F]9 and 30% to 40% nonspecific binding for [(18)F]15; however, it is still too high in order to compensate for its lower affinity. Even though the affinity of 9 is more promising compared with 15, the high nonspecific binding of both radiofluorinated tracers in rat brain does not recommend those as an in vivo PET imaging agent for serotonin 5-HT(2A) receptors in humans.
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Herth MM, Piel M, Debus F, Schmitt U, Lüddens H, Rösch F. Preliminary in vivo and ex vivo evaluation of the 5-HT2A imaging probe [(18)F]MH.MZ. Nucl Med Biol 2009; 36:447-54. [PMID: 19423013 DOI: 10.1016/j.nucmedbio.2009.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 01/16/2009] [Accepted: 01/25/2009] [Indexed: 11/30/2022]
Abstract
INTRODUCTION The 5-HT(2A) receptor is one of the most interesting targets within the serotonergic system because it is involved in a number of important physiological processes and diseases. METHODS [(18)F]MH.MZ, a 5-HT(2A) antagonistic receptor ligand, is labeled by (18)F-fluoroalkylation of the corresponding desmethyl analogue MDL 105725 with 2-[(18)F]fluoroethyltosylate ([(18)F]FETos). In vitro binding experiments were performed to test selectivity toward a broad spectrum of neuroreceptors by radioligand binding assays. Moreover, first micro-positron emission tomography (microPET) experiments, ex vivo organ biodistribution, blood cell and protein binding and brain metabolism studies of [(18)F]MH.MZ were carried out in rats. RESULTS [(18)F]MH.MZ showed a K(i) of 3 nM toward the 5-HT(2A) receptor and no appreciable affinity for a variety of receptors and transporters. Ex vivo biodistribution as well as microPET showed highest brain uptake at approximately 5 min p.i. and steady state after approximately 30 min p.i. While [(18)F]MH.MZ undergoes extensive first-pass metabolism which significantly reduces its bioavailability, it is insignificantly metabolized within the brain. The binding potential in the rat frontal cortex is 1.45, whereas the cortex to cerebellum ratio was determined to be 2.7 after approximately 30 min. CONCLUSION Results from microPET measurements of [(18)F]MH.MZ are in no way inferior to data known for [(11)C]MDL 100907 at least in rats. [(18)F]MH.MZ appears to be a highly potent and selective serotonergic PET ligand in small animals.
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Affiliation(s)
- Matthias M Herth
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, D-55128 Mainz, Germany.
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