51
|
Downey J, Bongarzone S, Hader S, Gee AD. In-loop flow [ 11 C]CO 2 fixation and radiosynthesis of N,N'-[ 11 C]dibenzylurea. J Labelled Comp Radiopharm 2018; 61:263-271. [PMID: 28977686 PMCID: PMC5900881 DOI: 10.1002/jlcr.3568] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/22/2017] [Accepted: 09/24/2017] [Indexed: 11/11/2022]
Abstract
Cyclotron-produced carbon-11 is a highly valuable radionuclide for the production of positron emission tomography (PET) radiotracers. It is typically produced as relatively unreactive carbon-11 carbon dioxide ([11 C]CO2 ), which is most commonly converted into a more reactive precursor for synthesis of PET radiotracers. The development of [11 C]CO2 fixation methods has more recently enabled the direct radiolabelling of a diverse array of structures directly from [11 C]CO2 , and the advantages afforded by the use of a loop-based system used in 11 C-methylation and 11 C-carboxylation reactions inspired us to apply the [11 C]CO2 fixation "in-loop." In this work, we developed and investigated a new ethylene tetrafluoroethylene (ETFE) loop-based [11 C]CO2 fixation method, enabling the fast and efficient, direct-from-cyclotron, in-loop trapping of [11 C]CO2 using mixed DBU/amine solutions. An optimised protocol was integrated into a proof-of-concept in-loop flow radiosynthesis of N,N'-[11 C]dibenzylurea. This reaction exhibited an average 78% trapping efficiency and a crude radiochemical purity of 83% (determined by radio-HPLC), giving an overall nonisolated radiochemical yield of 72% (decay-corrected) within just 3 minutes from end of bombardment. This proof-of-concept reaction has demonstrated that efficient [11 C]CO2 fixation can be achieved in a low-volume (150 μL) ETFE loop and that this can be easily integrated into a rapid in-loop flow radiosynthesis of carbon-11-labelled products. This new in-loop methodology will allow fast radiolabelling reactions to be performed using cheap/disposable ETFE tubing setup (ideal for good manufacturing practice production) thereby contributing to the widespread usage of [11 C]CO2 trapping/fixation reactions for the production of PET radiotracers.
Collapse
Affiliation(s)
- Joseph Downey
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
| | - Salvatore Bongarzone
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
| | - Stefan Hader
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
| | - Antony D. Gee
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
| |
Collapse
|
52
|
Boscutti G, Huiban M, Passchier J. Use of carbon-11 labelled tool compounds in support of drug development. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017; 25:3-10. [PMID: 29233265 DOI: 10.1016/j.ddtec.2017.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/15/2017] [Accepted: 11/16/2017] [Indexed: 06/07/2023]
Abstract
The pharmaceutical industry is facing key challenges to improve return on R&D investment. Positron emission tomography (PET), by itself or in combination with complementary technologies such as magnetic resonance imaging (MRI), provides a unique opportunity to confirm a candidate's ability to meet the so-called 'three pillars' of drug development. Positive confirmation provides confidence for go/no-go decision making at an early stage of the development process and enables informed clinical progression. Whereas fluorine-18 has probably gained wider use in the community, there are benefits to using carbon-11 given the greater flexibility the use of this isotope permits in adaptive clinical study design. This review explores the scope of available carbon-11 chemistries and provides clinical examples to highlight its value in PET studies in support of drug development.
Collapse
Affiliation(s)
- Giulia Boscutti
- Imanova Ltd., Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Mickael Huiban
- Imanova Ltd., Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Jan Passchier
- Imanova Ltd., Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
| |
Collapse
|
53
|
Filp U, Pees AL, Taddei C, Pekošak A, Gee AD, Windhorst AD, Poot AJ. Efficient Synthesis of11C-Acrylesters,11C-Acrylamides and Their Application in Michael Addition Reactions for PET Tracer Development. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700932] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Ulrike Filp
- VU University Medical Center; Department of Radiology and Nuclear Medicine; De Boelelaan 1085c 1081 HV Amsterdam The Netherlands
| | - Anna L. Pees
- VU University Medical Center; Department of Radiology and Nuclear Medicine; De Boelelaan 1085c 1081 HV Amsterdam The Netherlands
| | - Carlotta Taddei
- Division of Imaging Sciences and Biomedical Engineering; King's College London; Lambeth Palace Road SE1 7EH London United Kingdom
| | - Aleksandra Pekošak
- VU University Medical Center; Department of Radiology and Nuclear Medicine; De Boelelaan 1085c 1081 HV Amsterdam The Netherlands
| | - Antony D. Gee
- Division of Imaging Sciences and Biomedical Engineering; King's College London; Lambeth Palace Road SE1 7EH London United Kingdom
| | - Albert D. Windhorst
- VU University Medical Center; Department of Radiology and Nuclear Medicine; De Boelelaan 1085c 1081 HV Amsterdam The Netherlands
| | - Alex J. Poot
- VU University Medical Center; Department of Radiology and Nuclear Medicine; De Boelelaan 1085c 1081 HV Amsterdam The Netherlands
| |
Collapse
|
54
|
Ma L, Placzek MS, Hooker JM, Vasdev N, Liang SH. [ 11C]Cyanation of arylboronic acids in aqueous solutions. Chem Commun (Camb) 2017; 53:6597-6600. [PMID: 28580477 PMCID: PMC5584069 DOI: 10.1039/c7cc02886e] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A copper-mediated 11C-cyanation method employing arylboronic acids and [11C]HCN has been developed. This method was applied to the radiochemical synthesis of a wide range of aromatic 11C-nitriles in aqueous solutions. The use of readily accessible arylboronic acids as precursors makes this method complementary to the well-established 11C-cyanation methods that utilize aryl halide precursors.
Collapse
Affiliation(s)
- Longle Ma
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Michael S. Placzek
- Harvard Medical School, Boston, MA, USA
- McLean Hospital, Belmont, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, USA
| | - Jacob M. Hooker
- Harvard Medical School, Boston, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| |
Collapse
|
55
|
Taddei C, Bongarzone S, Gee AD. Instantaneous Conversion of [ 11 C]CO 2 to [ 11 C]CO via Fluoride-Activated Disilane Species. Chemistry 2017; 23:7682-7685. [PMID: 28419627 PMCID: PMC5488231 DOI: 10.1002/chem.201701661] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Indexed: 01/03/2023]
Abstract
The development of a fast and novel methodology to generate carbon-11 carbon monoxide ([11 C]CO) from cyclotron-produced carbon-11 carbon dioxide ([11 C]CO2 ) mediated by a fluoride-activated disilane species is described. This methodology allows up to 74 % conversion of [11 C]CO2 to [11 C]CO using commercially available reagents, readily available laboratory equipment and mild reaction conditions (room temperature). As proof of utility, radiochemically pure [carbonyl-11 C]N-benzylbenzamide was successfully synthesized from produced [11 C]CO in up to 74 % radiochemical yield (RCY) and >99 % radiochemical purity (RCP) in ≤10 min from end of [11 C]CO2 delivery.
Collapse
Affiliation(s)
- Carlotta Taddei
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor Lambeth WingSt. Thomas' HospitalLondonLambeth Palace RoadSE1 7EHUnited Kingdom
| | - Salvatore Bongarzone
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor Lambeth WingSt. Thomas' HospitalLondonLambeth Palace RoadSE1 7EHUnited Kingdom
| | - Antony D. Gee
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor Lambeth WingSt. Thomas' HospitalLondonLambeth Palace RoadSE1 7EHUnited Kingdom
| |
Collapse
|
56
|
Dahl K, Halldin C, Schou M. New methodologies for the preparation of carbon-11 labeled radiopharmaceuticals. Clin Transl Imaging 2017; 5:275-289. [PMID: 28596949 PMCID: PMC5437136 DOI: 10.1007/s40336-017-0223-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 02/01/2017] [Indexed: 12/04/2022]
Abstract
PURPOSE This short review aims to cover the more recent and promising developments of carbon-11 (11C) labeling radiochemistry and its utility in the production of novel radiopharmaceuticals, with special emphasis on methods that have the greatest potential to be translated for clinical positron emission tomography (PET) imaging. METHODS A survey of the literature was undertaken to identify articles focusing on methodological development in 11C chemistry and their use within novel radiopharmaceutical preparation. However, since 11C-labeling chemistry is such a narrow field of research, no systematic literature search was therefore feasible. The survey was further restricted to a specific timeframe (2000-2016) and articles in English. RESULTS From the literature, it is clear that the majority of 11C-labeled radiopharmaceuticals prepared for clinical PET studies have been radiolabeled using the standard heteroatom methylation reaction. However, a number of methodologies have been developed in recent years, both from a technical and chemical point of view. Amongst these, two protocols may have the greatest potential to be widely adapted for the preparation of 11C-radiopharmaceuticals in a clinical setting. First, a novel method for the direct formation of 11C-labeled carbonyl groups, where organic bases are utilized as [11C]carbon dioxide-fixation agents. The second method of clinical importance is a low-pressure 11C-carbonylation technique that utilizes solvable xenon gas to effectively transfer and react [11C]carbon monoxide in a sealed reaction vessel. Both methods appear to be general and provide simple paths to 11C-labeled products. CONCLUSION Radiochemistry is the foundation of PET imaging which relies on the administration of a radiopharmaceutical. The demand for new radiopharmaceuticals for clinical PET imaging is increasing, and 11C-radiopharmaceuticals are especially important within clinical research and drug development. This review gives a comprehensive overview of the most noteworthy 11C-labeling methods with clinical relevance to the field of PET radiochemistry.
Collapse
Affiliation(s)
- Kenneth Dahl
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Neuroscience, AstraZeneca Translational Science Centre, Karolinska Institutet, 171 76 Stockholm, Sweden
| |
Collapse
|
57
|
Ahamed M, Verbeek J, Funke U, Lecina J, Verbruggen A, Bormans G. Recent Progress in Metal Catalyzed Direct Carboxylation of Aryl Halides and Pseudo Halides Employing CO2: Opportunities for11C Radiochemistry. ChemCatChem 2016. [DOI: 10.1002/cctc.201600943] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | | | - Uta Funke
- Laboratory of Radiopharmacy; KU Leuven; Belgium
| | - Joan Lecina
- Laboratory of Radiopharmacy; KU Leuven; Belgium
| | | | - Guy Bormans
- Laboratory of Radiopharmacy; KU Leuven; Belgium
| |
Collapse
|
58
|
Xing J, Brooks AF, Fink D, Zhang H, Piert MR, Scott PJH, Shao X. High-Yielding Automated Convergent Synthesis of No-Carrier-Added [ 11C- Carbonyl]-Labeled Amino Acids Using the Strecker Reaction. Synlett 2016; 28:371-375. [PMID: 29430080 DOI: 10.1055/s-0036-1588638] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A new variant of the Strecker synthesis using no-carrier-added [11C]cyanide for the synthesis of radiolabeled amino acids is described. The protocol is fully automated using a radiochemistry synthesis module and applied to the production of a number of new PET radiotracers. [11C-Carbonyl]sarcosine, [11C-carbonyl]methionine, [11C-carbonyl]-N-phenylglycine, and [11C-carbonyl]glycine are all synthesized in moderate to good radiochemical yields. The synthesis of [11C-carbonyl]sarcosine has been validated for production of doses for clinical use, and preliminary evaluation of the new radiotracer in PC3 tumor-bearing mice is also reported.
Collapse
Affiliation(s)
- Junhao Xing
- Department of Radiology, University of Michigan Medical School, 2276 Med Sci I/SPC5610, 1301 Catherine St, Ann Arbor, MI 48109, USA.,Center of Drug Discovery, State Key Laboratory of Natural Medicines, Chinese Pharmaceutical University, 24 Tongjiaxiang, Nanjing 21009, P. R. of China
| | - Allen F Brooks
- Department of Radiology, University of Michigan Medical School, 2276 Med Sci I/SPC5610, 1301 Catherine St, Ann Arbor, MI 48109, USA
| | - Dylan Fink
- Department of Radiology, University of Michigan Medical School, 2276 Med Sci I/SPC5610, 1301 Catherine St, Ann Arbor, MI 48109, USA
| | - Huibin Zhang
- Center of Drug Discovery, State Key Laboratory of Natural Medicines, Chinese Pharmaceutical University, 24 Tongjiaxiang, Nanjing 21009, P. R. of China
| | - Morand R Piert
- Department of Radiology, University of Michigan Medical School, 2276 Med Sci I/SPC5610, 1301 Catherine St, Ann Arbor, MI 48109, USA
| | - Peter J H Scott
- Department of Radiology, University of Michigan Medical School, 2276 Med Sci I/SPC5610, 1301 Catherine St, Ann Arbor, MI 48109, USA.,Interdepartmental Program in Medicinal Chemistry, University of Michigan, 428 Church St, Ann Arbor, MI 48109, USA
| | - Xia Shao
- Department of Radiology, University of Michigan Medical School, 2276 Med Sci I/SPC5610, 1301 Catherine St, Ann Arbor, MI 48109, USA
| |
Collapse
|
59
|
Thompson S, Kilbourn MR, Scott PJH. Radiochemistry, PET Imaging, and the Internet of Chemical Things. ACS CENTRAL SCIENCE 2016; 2:497-505. [PMID: 27610410 PMCID: PMC4999973 DOI: 10.1021/acscentsci.6b00178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Indexed: 06/06/2023]
Abstract
The Internet of Chemical Things (IoCT), a growing network of computers, mobile devices, online resources, software suites, laboratory equipment, synthesis apparatus, analytical devices, and a host of other machines, all interconnected to users, manufacturers, and others through the infrastructure of the Internet, is changing how we do chemistry. While in its infancy across many chemistry laboratories and departments, it became apparent when considering our own work synthesizing radiopharmaceuticals for positron emission tomography (PET) that a more mature incarnation of the IoCT already exists. How does the IoCT impact our lives today, and what does it hold for the smart (radio)chemical laboratories of the future?
Collapse
Affiliation(s)
- Stephen Thompson
- Department of Radiology and The Interdepartmental Program in
Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Michael R. Kilbourn
- Department of Radiology and The Interdepartmental Program in
Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Department of Radiology and The Interdepartmental Program in
Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
60
|
Rotstein BH, Placzek MS, Krishnan HS, Pekošak A, Collier TL, Wang C, Liang SH, Burstein ES, Hooker JM, Vasdev N. Preclinical PET Neuroimaging of [11C]Bexarotene. Mol Imaging 2016; 15:15/0/1536012116663054. [PMID: 27553293 PMCID: PMC5011434 DOI: 10.1177/1536012116663054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 07/06/2016] [Indexed: 12/20/2022] Open
Abstract
Activation of retinoid X receptors (RXRs) has been proposed as a therapeutic mechanism for the treatment of neurodegeneration, including Alzheimer's and Parkinson's diseases. We previously reported radiolabeling of a Food and Drug Administration-approved RXR agonist, bexarotene, by copper-mediated [11C]CO2 fixation and preliminary positron emission tomography (PET) neuroimaging that demonstrated brain permeability in nonhuman primate with regional binding distribution consistent with RXRs. In this study, the brain uptake and saturability of [11C]bexarotene were studied in rats and nonhuman primates by PET imaging under baseline and greater target occupancy conditions. [11C]Bexarotene displays a high proportion of nonsaturable uptake in the brain and is unsuitable for RXR occupancy measurements in the central nervous system.
Collapse
Affiliation(s)
- Benjamin H Rotstein
- Division of Nuclear Medicine and Molecular Imaging, Gordon Center for Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Michael S Placzek
- Department of Radiology, Harvard Medical School, Boston, MA, USA Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA Department of Psychiatry, McLean Imaging Center, McLean Hospital, Belmont, MA, USA
| | - Hema S Krishnan
- Division of Nuclear Medicine and Molecular Imaging, Gordon Center for Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Aleksandra Pekošak
- Division of Nuclear Medicine and Molecular Imaging, Gordon Center for Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Thomas Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Gordon Center for Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA Department of Radiology, Harvard Medical School, Boston, MA, USA Advion, Inc, Ithaca, NY, USA
| | - Changning Wang
- Department of Radiology, Harvard Medical School, Boston, MA, USA Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Gordon Center for Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA Department of Radiology, Harvard Medical School, Boston, MA, USA
| | | | - Jacob M Hooker
- Department of Radiology, Harvard Medical School, Boston, MA, USA Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Gordon Center for Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA Department of Radiology, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
61
|
Rotstein BH, Liang SH, Placzek MS, Hooker JM, Gee AD, Dollé F, Wilson AA, Vasdev N. (11)C[double bond, length as m-dash]O bonds made easily for positron emission tomography radiopharmaceuticals. Chem Soc Rev 2016; 45:4708-26. [PMID: 27276357 PMCID: PMC5000859 DOI: 10.1039/c6cs00310a] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The positron-emitting radionuclide carbon-11 ((11)C, t1/2 = 20.3 min) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [(11)C]methyl iodide or [(11)C]methyl triflate (generated from [(11)C]carbon dioxide or [(11)C]methane). Consequently, small molecules that lack an easily substituted (11)C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [(11)C]Carbon dioxide itself, [(11)C]carbon monoxide, [(11)C]cyanide, and [(11)C]phosgene represent alternative reactants to enable (11)C-carbonylation. Methodologies developed for preparation of (11)C-carbonyl groups have had a tremendous impact on the development of novel PET tracers and provided key tools for clinical research. (11)C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility and practicality of the underlying radiochemistry.
Collapse
Affiliation(s)
| | - Steven H Liang
- Massachusetts General Hospital, Harvard Medical School, Boston, USA.
| | - Michael S Placzek
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, HMS, Charlestown, USA and McLean Hospital, Belmont, USA
| | - Jacob M Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, HMS, Charlestown, USA
| | | | - Frédéric Dollé
- CEA - Institut d'imagerie biomédicale, Service hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Alan A Wilson
- Centre for Addiction and Mental Health, Toronto, Canada
| | - Neil Vasdev
- Massachusetts General Hospital, Harvard Medical School, Boston, USA.
| |
Collapse
|
62
|
Sawatzky E, Al-Momani E, Kobayashi R, Higuchi T, Samnick S, Decker M. A Novel Way To Radiolabel Human Butyrylcholinesterase for Positron Emission Tomography through Irreversible Transfer of the Radiolabeled Moiety. ChemMedChem 2016; 11:1540-50. [DOI: 10.1002/cmdc.201600223] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 05/30/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Edgar Sawatzky
- Pharmaceutical and Medicinal Chemistry; Institute of Pharmacy and Food Chemistry; Julius Maximilian University Würzburg; Am Hubland 97074 Würzburg Germany
| | - Ehab Al-Momani
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Ryohei Kobayashi
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Takahiro Higuchi
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Samuel Samnick
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Michael Decker
- Pharmaceutical and Medicinal Chemistry; Institute of Pharmacy and Food Chemistry; Julius Maximilian University Würzburg; Am Hubland 97074 Würzburg Germany
| |
Collapse
|
63
|
Mossine AV, Brooks AF, Jackson IM, Quesada CA, Sherman P, Cole EL, Donnelly DJ, Scott PJH, Shao X. Synthesis of Diverse (11)C-Labeled PET Radiotracers via Direct Incorporation of [(11)C]CO2. Bioconjug Chem 2016; 27:1382-9. [PMID: 27043721 PMCID: PMC5637095 DOI: 10.1021/acs.bioconjchem.6b00163] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three new positron emission tomography (PET) radiotracers of interest to our functional neuroimaging and translational oncology programs have been prepared through new developments in [(11)C]CO2 fixation chemistry. [(11)C]QZ (glutaminyl cyclase) was prepared via a tandem trapping of [(11)C]CO2/intramolecular cyclization; [(11)C]tideglusib (glycogen synthase kinase-3) was synthesized through a tandem trapping of [(11)C]CO2 followed by an intermolecular cycloaddition between a [(11)C]isocyanate and an isothiocyanate to form the 1,2,4-thiadiazolidine-3,5-dione core; [(11)C]ibrutinib (Bruton's tyrosine kinase) was synthesized through a HATU peptide coupling of an amino precursor with [(11)C]acrylic acid (generated from [(11)C]CO2 fixation with vinylmagnesium bromide). All radiochemical syntheses are fully automated on commercial radiochemical synthesis modules and provide radiotracers in 1-5% radiochemical yield (noncorrected, based upon [(11)C]CO2). All three radiotracers have advanced to rodent imaging studies and preliminary PET imaging results are also reported.
Collapse
Affiliation(s)
- Andrew V. Mossine
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Allen F. Brooks
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Isaac M. Jackson
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Carole A. Quesada
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Phillip Sherman
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Erin L. Cole
- Discovery Chemistry Platforms, PET Radiochemical Synthesis, Bristol-Myers Squibb Research and Development, Princeton, NJ, USA
| | - David J. Donnelly
- Discovery Chemistry Platforms, PET Radiochemical Synthesis, Bristol-Myers Squibb Research and Development, Princeton, NJ, USA
| | - Peter J. H. Scott
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
- The Interdepartmental Program in Medicinal Chemistry, The University of Michigan, Ann Arbor, MI, USA
| | - Xia Shao
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| |
Collapse
|
64
|
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.
Collapse
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.
| |
Collapse
|
65
|
Recent Advances in the Development and Application of Radiolabeled Kinase Inhibitors for PET Imaging. Molecules 2015; 20:22000-27. [PMID: 26690113 PMCID: PMC6332294 DOI: 10.3390/molecules201219816] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 11/18/2015] [Accepted: 12/01/2015] [Indexed: 12/20/2022] Open
Abstract
Over the last 20 years, intensive investigation and multiple clinical successes targeting protein kinases, mostly for cancer treatment, have identified small molecule kinase inhibitors as a prominent therapeutic class. In the course of those investigations, radiolabeled kinase inhibitors for positron emission tomography (PET) imaging have been synthesized and evaluated as diagnostic imaging probes for cancer characterization. Given that inhibitor coverage of the kinome is continuously expanding, in vivo PET imaging will likely find increasing applications for therapy monitoring and receptor density studies both in- and outside of oncological conditions. Early investigated radiolabeled inhibitors, which are mostly based on clinically approved tyrosine kinase inhibitor (TKI) isotopologues, have now entered clinical trials. Novel radioligands for cancer and PET neuroimaging originating from novel but relevant target kinases are currently being explored in preclinical studies. This article reviews the literature involving radiotracer design, radiochemistry approaches, biological tracer evaluation and nuclear imaging results of radiolabeled kinase inhibitors for PET reported between 2010 and mid-2015. Aspects regarding the usefulness of pursuing selective vs. promiscuous inhibitor scaffolds and the inherent challenges associated with intracellular enzyme imaging will be discussed.
Collapse
|
66
|
Liger F, Eijsbouts T, Cadarossanesaib F, Tourvieille C, Le Bars D, Billard T. Direct [11C]Methylation of Amines from [11C]CO2for the Synthesis of PET Radiotracers. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500924] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
67
|
Abstract
The logic of total synthesis transformed a stagnant state of medicinal and synthetic organic chemistry when there was a paucity of methods and reagents to synthesize drug molecules and/or natural products. Molecular imaging by positron emission tomography (PET) is now experiencing a renaissance in the way radiopharmaceuticals for molecular imaging are synthesized, however, a paradigm shift is desperately needed in the discovery pipeline to accelerate in vivo imaging studies. A significant challenge in radiochemistry is the limited choice of labeled reagents (or building blocks) available for the synthesis of novel radiopharmaceuticals with the most commonly used short-lived radionuclides carbon-11 (11C; half-life ~20 minutes) and fluorine-18 (18F; half-life ~2 hours). In fact, most drugs cannot be labeled with 11C or 18F due to a lack of efficient and diverse radiosynthetic methods. In general, routine radiopharmaceutical production relies on the incorporation of the isotope at the last or penultimate step of synthesis, ideally within one half-life of the radionuclide, to maximize radiochemical yields and specific activities thereby reducing losses due to radioactive decay. Reliance on radiochemistry conducted within the constraints of an automated synthesis unit ("box") has stifled the exploration of multi-step reactions with short-lived radionuclides. Radiopharmaceutical synthesis can be transformed by considering logic of total synthesis to develop novel approaches for 11C- and 18F-radiolabeling complex molecules via retrosynthetic analysis and multi-step reactions. As a result of such exploration, new methods, reagents and radiopharmaceuticals for in vivo imaging studies are discovered. A new avenue to develop radiotracers that were previously unattainable due to the lack of efficient radiosynthetic methods is necessary to work towards our ultimate, albeit impossible goal - the concept we term total radiosynthesis - to radiolabel virtually any molecule. As with the vast majority of drugs, most radiotracers also fail, therefore expeditious evaluation of tracers in preclinical models prior to optimization or derivatization of the lead molecules/drugs is necessary. Furthermore the exact position of the 11C and 18F radionuclide in tracers is often critical for metabolic considerations, and flexible methodologies to introduce the radiolabel are needed. Using the principles of total synthesis our laboratory and others have shown that multi-step radiochemical reactions are indeed suitable for preclinical and even clinical use. As the goal of total synthesis is to be concise, we have also simplified the syntheses of radiopharmaceuticals. We are presently developing new strategies via [11C]CO2 fixation which has enabled library radiosynthesis as well as labeling non-activated arenes using [18F]fluoride via iodonium ylides. Both of which have proven to be suitable for human PET imaging. We concurrently utilize state-of-the-art automation technologies including microfluidic flow chemistry and rapid purification strategies for radiopharmaceutical production. In this account we highlight how total radiosynthesis has impacted our radiochemistry program, with prominent examples from others, focusing on its impact towards preclinical and clinical research studies.
Collapse
Affiliation(s)
- Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA
| |
Collapse
|
68
|
Testa A, Zanda M, Elmore CS, Sharma P. PET Tracers To Study Clinically Relevant Hepatic Transporters. Mol Pharm 2015; 12:2203-16. [DOI: 10.1021/acs.molpharmaceut.5b00059] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Andrea Testa
- Kosterlitz
Centre for Therapeutics, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, U.K
| | - Matteo Zanda
- Kosterlitz
Centre for Therapeutics, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, U.K
| | | | - Pradeep Sharma
- AstraZeneca R&D, Cambridge Science Park, Milton Road, Cambridge CB4 0WG, U.K
| |
Collapse
|
69
|
Honer M, Gobbi L, Martarello L, Comley RA. Radioligand development for molecular imaging of the central nervous system with positron emission tomography. Drug Discov Today 2014; 19:1936-44. [DOI: 10.1016/j.drudis.2014.08.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/24/2014] [Accepted: 08/21/2014] [Indexed: 11/25/2022]
|
70
|
Cai H, Mangner TJ, Muzik O, Wang MW, Chugani DC, Chugani HT. Radiosynthesis of (11)C-Levetiracetam: A Potential Marker for PET Imaging of SV2A Expression. ACS Med Chem Lett 2014; 5:1152-5. [PMID: 25313330 DOI: 10.1021/ml500285t] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 08/19/2014] [Indexed: 11/30/2022] Open
Abstract
The multistep preparation of (11)C-levetiracetam ((11)C-LEV) was carried out by a one-pot radiosynthesis with 8.3 ± 1.6% (n = 8) radiochemical yield in 50 ± 5.0 min. Briefly, the propionaldehyde was converted to propan-1-imine in situ as labeling precursor by incubation with ammonia. Without further separation, the imine was reacted with (11)C-HCN to form (11)C-aminonitrile. This crude was then reacted with 4-chlorobutyryl chloride and followed by hydrolysis to yield (11)C-LEV after purification by chiral high-performance liquid chromatography (HPLC). Both the radiochemical and enantiomeric purities of (11)C-LEV were >98%.
Collapse
Affiliation(s)
- Hancheng Cai
- PET
Center, Children’s Hospital of Michigan, Detroit Medical Center, Detroit, Michigan 48201, United States
| | - Thomas J. Mangner
- PET
Center, Children’s Hospital of Michigan, Detroit Medical Center, Detroit, Michigan 48201, United States
| | - Otto Muzik
- PET
Center, Children’s Hospital of Michigan, Detroit Medical Center, Detroit, Michigan 48201, United States
| | | | - Diane C. Chugani
- PET
Center, Children’s Hospital of Michigan, Detroit Medical Center, Detroit, Michigan 48201, United States
| | - Harry T. Chugani
- PET
Center, Children’s Hospital of Michigan, Detroit Medical Center, Detroit, Michigan 48201, United States
| |
Collapse
|
71
|
The design and performance of a portable handheld (11)CO2 delivery system. Appl Radiat Isot 2014; 94:338-343. [PMID: 25305526 DOI: 10.1016/j.apradiso.2014.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 11/22/2022]
Abstract
We constructed a hand-held device to efficiently trap [(11)C]CO2 from the cyclotron target, safely transport up to 3.7GBq (100mCi) doses to remote sites and release it without the need for a liquid cryogen. The system consists of a 180W furnace and a miniature molecular sieve trap (80-100mg; 80-100mesh 13×) placed inside a lead pig weighing 11.1kg. The overall [(11)C]CO2 delivery efficiency of the device is ~82% (> 99% trapping efficiency). Radiation dose rates measured at 30cm from the surface of the pig are <43.5µSv/h (5mR/h) up to 2.59GBq (70mCi).
Collapse
|
72
|
Rotstein BH, Wey HY, Shoup TM, Wilson AA, Liang SH, Hooker JM, Vasdev N. PET imaging of fatty acid amide hydrolase with [(18)F]DOPP in nonhuman primates. Mol Pharm 2014; 11:3832-8. [PMID: 25004399 PMCID: PMC4224570 DOI: 10.1021/mp500316h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Fatty acid amide hydrolase (FAAH) regulates endocannabinoid signaling. [(11)C]CURB, an irreversibly binding FAAH inhibitor, has been developed for clinical research imaging with PET. However, no fluorine-18 labeled radiotracer for FAAH has yet advanced to human studies. [(18)F]DOPP ([(18)F]3-(4,5-dihydrooxazol-2-yl)phenyl (5-fluoropentyl)carbamate) has been identified as a promising (18)F-labeled analogue based on rodent studies. The goal of this work is to evaluate [(18)F]DOPP in nonhuman primates to support its clinical translation. High specific activity [(18)F]DOPP (5-6 Ci·μmol(-1)) was administered intravenously (iv) to three baboons (2M/1F, 3-4 years old). The distribution and pharmacokinetics were quantified following a 2 h dynamic imaging session using a simultaneous PET/MR scanner. Pretreatment with the FAAH-selective inhibitor, URB597, was carried out at 200 or 300 μg/kg iv, 10 min prior to [(18)F]DOPP administration. Rapid arterial blood sampling for the first 3 min was followed by interval sampling with metabolite analysis to provide a parent radiotracer plasma input function that indicated ∼95% baseline metabolism at 60 min and a reduced rate of metabolism after pretreatment with URB597. Regional distribution data were analyzed with 1-, 2-, and 3-tissue compartment models (TCMs), with and without irreversible trapping since [(18)F]DOPP covalently links to the active site of FAAH. Consistent with previous findings for [(11)C]CURB, the 2TCM with irreversible binding was found to provide the best fit for modeling the data in all regions. The composite parameter λk3 was therefore used to evaluate whole brain (WB) and regional binding of [(18)F]DOPP. Pretreatment studies showed inhibition of λk3 across all brain regions (WB baseline: 0.112 mL/cm(3)/min; 300 μg/kg URB597: 0.058 mL/cm(3)/min), suggesting that [(18)F]DOPP binding is specific for FAAH, consistent with previous rodent data.
Collapse
Affiliation(s)
- Benjamin H Rotstein
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital , Boston, Massachusetts 02114, United States
| | | | | | | | | | | | | |
Collapse
|
73
|
Rotstein B, Hooker JM, Woo J, Collier T, Brady T, Liang SH, Vasdev N. Synthesis of [(11)C]Bexarotene by Cu-Mediated [(11)C]Carbon Dioxide Fixation and Preliminary PET Imaging. ACS Med Chem Lett 2014; 5:668-72. [PMID: 24944741 PMCID: PMC4060930 DOI: 10.1021/ml500065q] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 02/27/2014] [Indexed: 12/22/2022] Open
Abstract
Bexarotene (Targretin) is a retinoid X receptor (RXR) agonist that has applications for treatment of T cell lymphoma and proposed mechanisms of action in Alzheimer's disease that have been the subject of recent controversy. Carbon-11 labeled bexarotene ([(11)C-carbonyl]4-[1-(3,5,5,8,8-pentamethyltetralin-2-yl)ethenyl]benzoic acid) was synthesized using a Cu-mediated cross-coupling reaction employing an arylboronate precursor 1 and [(11)C]carbon dioxide under atmospheric pressure in 15 ± 2% uncorrected radiochemical yield (n = 3), based on [(11)C]CO2. Judicious choice of solvents, catalysts, and additives, as well as precursor concentration and purity of [(11)C]CO2, enabled the preparation of this (11)C-labeled carboxylic acid. Formulated [(11)C]bexarotene was isolated (>37 mCi) with >99% radiochemical purity in 32 min. Preliminary positron emission tomography-magnetic resonance imaging revealed rapid brain uptake in nonhuman primate in the first 75 s following intravenous administration of the radiotracer (specific activity >0.3 Ci/μmol at time of injection), followed by slow clearance (Δ = -43%) over 60 min. Modest uptake (SUVmax = 0.8) was observed in whole brain and regions with high RXR expression.
Collapse
Affiliation(s)
- Benjamin
H. Rotstein
- Division
of Nuclear Medicine and Molecular Imaging & Center for Advanced
Medical Imaging Sciences, Massachusetts
General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Jacob M. Hooker
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
- Athinoula
A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Jiyeon Woo
- Division
of Nuclear Medicine and Molecular Imaging & Center for Advanced
Medical Imaging Sciences, Massachusetts
General Hospital, Boston, Massachusetts 02114, United States
| | - Thomas
Lee Collier
- Division
of Nuclear Medicine and Molecular Imaging & Center for Advanced
Medical Imaging Sciences, Massachusetts
General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
- Advion,
Inc., Ithaca, New York 14850, United
States
| | - Thomas
J. Brady
- Division
of Nuclear Medicine and Molecular Imaging & Center for Advanced
Medical Imaging Sciences, Massachusetts
General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Steven H. Liang
- Division
of Nuclear Medicine and Molecular Imaging & Center for Advanced
Medical Imaging Sciences, Massachusetts
General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Neil Vasdev
- Division
of Nuclear Medicine and Molecular Imaging & Center for Advanced
Medical Imaging Sciences, Massachusetts
General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| |
Collapse
|
74
|
Nagaki A, Takahashi Y, Yoshida JI. Extremely Fast Gas/Liquid Reactions in Flow Microreactors: Carboxylation of Short-Lived Organolithiums. Chemistry 2014; 20:7931-4. [DOI: 10.1002/chem.201402520] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Indexed: 11/09/2022]
|
75
|
Hicks JW, Parkes J, Tong J, Houle S, Vasdev N, Wilson AA. Radiosynthesis and ex vivo evaluation of [(11)C-carbonyl]carbamate- and urea-based monoacylglycerol lipase inhibitors. Nucl Med Biol 2014; 41:688-94. [PMID: 24969632 DOI: 10.1016/j.nucmedbio.2014.05.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 04/16/2014] [Accepted: 05/01/2014] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH) are the two primary enzymes that regulate the tone of endocannabinoid signaling. Although new PET radiotracers have been discovered for imaging FAAH in vivo, no such radiotracer exists for imaging MAGL. Here we report the radiosynthesis of five candidate MAGL radiotracers and their ex vivo evaluations in mice and rats. METHODS Candidate carbamate and urea MAGL inhibitors were radiolabeled at the carbonyl position by [(11)C]CO2 fixation. Radiotracers were administered (tail-vein injection) to rodents and brain uptake of radioactivity measured at early and late time points ex vivo. Specificity of uptake was explored by pretreatment with unlabeled inhibitors (2 mg/kg, ip) 30 min prior to radiotracer administration. RESULTS All five candidate MAGL radiotracers were prepared in high specific activity (>65 GBq/μmol) and radiochemical purity (>98%). Moderate brain uptake (0.2-0.8 SUV) was observed for each candidate while pretreatment did not reduce uptake for four of the five tested. For two candidates ([(11)C]12 and [(11)C]14), high retention of radioactivity was observed in the blood (ca. 10 and 4 SUV at 40 min) which was blocked by pretreatment with unlabeled inhibitors. The most promising candidate, [(11)C]18, demonstrated moderate brain uptake (ca. 0.8 SUV) which showed circa 50% blockade by pretreatment with unlabeled 18. CONCLUSION One putative and four reported potent and selective MAGL inhibitors have been radiolabeled via [(11)C]CO2 fixation as radiotracers for this enzyme. Despite the promising in vitro pharmacological profile, none of the five candidate radiotracers exhibited in vivo behavior suitable for PET neuroimaging.
Collapse
Affiliation(s)
- Justin W Hicks
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada, M5T 1R8; Institute of Medical Science, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Jun Parkes
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada, M5T 1R8
| | - Junchao Tong
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada, M5T 1R8
| | - Sylvain Houle
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada, M5T 1R8
| | - Neil Vasdev
- Department of Radiology, Harvard Medical School and Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA, 02114
| | - Alan A Wilson
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada, M5T 1R8; Institute of Medical Science, University of Toronto, Toronto, ON, Canada, M5S 1A8.
| |
Collapse
|
76
|
Rusjan PM, Wilson AA, Miler L, Fan I, Mizrahi R, Houle S, Vasdev N, Meyer JH. Kinetic modeling of the monoamine oxidase B radioligand [¹¹C]SL25.1188 in human brain with high-resolution positron emission tomography. J Cereb Blood Flow Metab 2014; 34:883-9. [PMID: 24517979 PMCID: PMC4013770 DOI: 10.1038/jcbfm.2014.34] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 12/25/2013] [Accepted: 01/20/2014] [Indexed: 11/09/2022]
Abstract
This article describes the kinetic modeling of [(11)C]SL25.1188 ([(S)-5-methoxymethyl-3-[6-(4,4,4-trifluorobutoxy)-benzo[d]isoxazol-3-yl]-oxazolidin-2-[(11)C]one]) binding to monoamine oxidase B (MAO-B) in the human brain using high-resolution positron emission tomography (PET). Seven healthy subjects underwent two separate 90- minute PET scans after an intravenous injection of [(11)C]SL25.1188. Complementary arterial blood sampling was acquired. Radioactivity was quickly eliminated from plasma with 80% of parent compound remaining at 90 minutes. Metabolites were more polar than the parent compound. Time-activity curves showed high brain uptake, early peak and washout rate consistent with known regional MAO-B concentration. A two-tissue compartment model (2-TCM) provided better fits to the data than a 1-TCM. Measurement of total distribution volume (VT) showed very good identifiability (based on coefficient of variation (COV)) for all regions of interest (ROIs) (COV(VT)<8%), low between-subject variability (∼20%), and quick temporal convergence (within 5% of final value at 45 minutes). Logan graphical method produces very good estimation of VT. Regional VT highly correlated with previous postmortem report of MAO-B level (r(2)= ≥ 0.9). Specific binding would account from 70% to 90% of VT. Hence, VT measurement of [(11)C]SL25.1(1)88 PET is an excellent estimation of MAO-B concentration.
Collapse
Affiliation(s)
- Pablo M Rusjan
- Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
| | - Alan A Wilson
- 1] Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada [2] Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Laura Miler
- Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
| | - Ian Fan
- Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
| | - Romina Mizrahi
- 1] Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada [2] Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Sylvain Houle
- 1] Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada [2] Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jeffrey H Meyer
- 1] Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada [2] Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|