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Chauveau F, Winkeler A, Chalon S, Boutin H, Becker G. PET imaging of neuroinflammation: any credible alternatives to TSPO yet? Mol Psychiatry 2024:10.1038/s41380-024-02656-9. [PMID: 38997465 DOI: 10.1038/s41380-024-02656-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/26/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.
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Affiliation(s)
- Fabien Chauveau
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
| | - Alexandra Winkeler
- Université Paris-Saclay, Inserm, CNRS, CEA, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401, Orsay, France
| | - Sylvie Chalon
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France
| | - Hervé Boutin
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France.
| | - Guillaume Becker
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
- Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail, 14 rue Pierre et Marie Curie, 94701, Maisons-Alfort, Cedex, France
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2
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Teodoro R, Gündel D, Deuther-Conrad W, Kazimir A, Toussaint M, Wenzel B, Bormans G, Hey-Hawkins E, Kopka K, Brust P, Moldovan RP. Synthesis, Structure-Activity Relationships, Radiofluorination, and Biological Evaluation of [ 18F]RM365, a Novel Radioligand for Imaging the Human Cannabinoid Receptor Type 2 (CB2R) in the Brain with PET. J Med Chem 2023; 66:13991-14010. [PMID: 37816245 PMCID: PMC10614203 DOI: 10.1021/acs.jmedchem.3c01035] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Indexed: 10/12/2023]
Abstract
The development of cannabinoid receptor type 2 (CB2R) PET radioligands has been intensively explored due to the pronounced CB2R upregulation under various pathological conditions. Herein, we report on the synthesis of a series of CB2R affine fluorinated indole-2-carboxamide ligands. Compound RM365 was selected for PET radiotracer development due to its high CB2R affinity (Ki = 2.1 nM) and selectivity over CB1R (factor > 300). Preliminary in vitro evaluation of [18F]RM365 indicated species differences in the binding to CB2R (KD of 2.32 nM for the hCB2R vs KD > 10,000 nM for the rCB2R). Metabolism studies in mice revealed a high in vivo stability of [18F]RM365. PET imaging in a rat model of local hCB2R(D80N) overexpression in the brain demonstrates the ability of [18F]RM365 to reach and selectively label the hCB2R(D80N) with a high signal-to-background ratio. Thus, [18F]RM365 is a very promising PET radioligand for the imaging of upregulated hCB2R expression under pathological conditions.
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Affiliation(s)
- Rodrigo Teodoro
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Daniel Gündel
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Aleksandr Kazimir
- Faculty
of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Magali Toussaint
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Barbara Wenzel
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Guy Bormans
- Radiopharmaceutical
Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, BE-3000 Leuven, Belgium
| | - Evamarie Hey-Hawkins
- Faculty
of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Klaus Kopka
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
- Faculty
of Chemistry and Food Chemistry, School of Science, TU Dresden, 01069 Dresden, Germany
| | - Peter Brust
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
- The
Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562 Lübeck, Germany
| | - Rareş-Petru Moldovan
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
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3
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Cools R, Kerkhofs K, Leitao RCF, Bormans G. Preclinical Evaluation of Novel PET Probes for Dementia. Semin Nucl Med 2023; 53:599-629. [PMID: 37149435 DOI: 10.1053/j.semnuclmed.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 05/08/2023]
Abstract
The development of novel PET imaging agents that selectively bind specific dementia-related targets can contribute significantly to accurate, differential and early diagnosis of dementia causing diseases and support the development of therapeutic agents. Consequently, in recent years there has been a growing body of literature describing the development and evaluation of potential new promising PET tracers for dementia. This review article provides a comprehensive overview of novel dementia PET probes under development, classified by their target, and pinpoints their preclinical evaluation pathway, typically involving in silico, in vitro and ex/in vivo evaluation. Specific target-associated challenges and pitfalls, requiring extensive and well-designed preclinical experimental evaluation assays to enable successful clinical translation and avoid shortcomings observed for previously developed 'well-established' dementia PET tracers are highlighted in this review.
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Affiliation(s)
- Romy Cools
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Kobe Kerkhofs
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium; NURA, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Renan C F Leitao
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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4
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Kallinen A, Mardon K, Lane S, Montgomery AP, Bhalla R, Stimson DHR, Ahamed M, Cowin GJ, Hibbs D, Werry EL, Fulton R, Connor M, Kassiou M. Synthesis and Preclinical Evaluation of Fluorinated 5-Azaindoles as CB2 PET Radioligands. ACS Chem Neurosci 2023; 14:2902-2921. [PMID: 37499194 DOI: 10.1021/acschemneuro.3c00345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023] Open
Abstract
Several classes of cannabinoid receptor type 2 radioligands have been evaluated for imaging of neuroinflammation, with successful clinical translation yet to take place. Here we describe the synthesis of fluorinated 5-azaindoles and pharmacological characterization and in vivo evaluation of 18F-radiolabeled analogues. [18F]2 (hCB2 Ki = 96.5 nM) and [18F]9 (hCB2 Ki = 7.7 nM) were prepared using Cu-mediated 18F-fluorination with non-decay-corrected radiochemical yields of 15 ± 6% and 18 ± 2% over 85 and 80 min, respectively, with high radiochemical purities (>97%) and molar activities (140-416 GBq/μmol). In PET imaging studies in rats, both [18F]2 and [18F]9 demonstrated specific binding in CB2-rich spleen after pretreatment with CB2-specific GW405833. Moreover, [18F]9 exhibited higher brain uptake at later time points in a murine model of neuroinflammation compared with a healthy control group. The results suggest further evaluation of azaindole based CB2 radioligands is warranted in other neuroinflammation models.
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Affiliation(s)
- Annukka Kallinen
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | - Karine Mardon
- ARC Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Samuel Lane
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | | | | | | | - Muneer Ahamed
- ARC Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Gary J Cowin
- ARC Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David Hibbs
- Sydney Pharmacy School, The University of Sydney, Sydney, NSW 2006, Australia
| | - Eryn L Werry
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | - Roger Fulton
- Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2050, Australia
| | - Mark Connor
- Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
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5
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The chronological evolution of fluorescent GPCR probes for bioimaging. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2023.215040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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6
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Teodoro R, Gündel D, Deuther-Conrad W, Ueberham L, Toussaint M, Bormans G, Brust P, Moldovan RP. Development of [ 18F]LU14 for PET Imaging of Cannabinoid Receptor Type 2 in the Brain. Int J Mol Sci 2021; 22:ijms22158051. [PMID: 34360817 PMCID: PMC8347709 DOI: 10.3390/ijms22158051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 12/16/2022] Open
Abstract
Cannabinoid receptors type 2 (CB2R) represent an attractive therapeutic target for neurodegenerative diseases and cancer. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor receptor density and/or occupancy during a CB2R-tailored therapy, we herein describe the radiosynthesis of cis-[18F]1-(4-fluorobutyl-N-((1s,4s)-4-methylcyclohexyl)-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamide ([18F]LU14) starting from the corresponding mesylate precursor. The first biological evaluation revealed that [18F]LU14 is a highly affine CB2R radioligand with >80% intact tracer in the brain at 30 min p.i. Its further evaluation by PET in a well-established rat model of CB2R overexpression demonstrated its ability to selectively image the CB2R in the brain and its potential as a tracer to further investigate disease-related changes in CB2R expression.
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Affiliation(s)
- Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Daniel Gündel
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Lea Ueberham
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Guy Bormans
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, BE-3000 Leuven, Belgium;
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
- The Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562 Lübeck, Germany
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
- Correspondence: ; Tel.: +49-3412-3417-94634
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7
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Novel late-stage radiosynthesis of 5-[18F]-trifluoromethyl-1,2,4-oxadiazole (TFMO) containing molecules for PET imaging. Sci Rep 2021; 11:10668. [PMID: 34021207 PMCID: PMC8139947 DOI: 10.1038/s41598-021-90069-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/05/2021] [Indexed: 12/26/2022] Open
Abstract
Small molecules that contain the (TFMO) moiety were reported to specifically inhibit the class-IIa histone deacetylases (HDACs), an important target in cancer and the disorders of the central nervous system (CNS). However, radiolabeling methods to incorporate the [18F]fluoride into the TFMO moiety are lacking. Herein, we report a novel late-stage incorporation of [18F]fluoride into the TFMO moiety in a single radiochemical step. In this approach the bromodifluoromethyl-1,2,4-oxadiazole was converted into [18F]TFMO via no-carrier-added bromine-[18F]fluoride exchange in a single step, thus producing the PET tracers with acceptable radiochemical yield (3–5%), high radiochemical purity (> 98%) and moderate molar activity of 0.33–0.49 GBq/umol (8.9–13.4 mCi/umol). We validated the utility of the novel radiochemical design by the radiosynthesis of [18F]TMP195, which is a known TFMO containing potent inhibitor of class-IIa HDACs.
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9
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Design and synthesis of fluorescent ligands for the detection of cannabinoid type 2 receptor (CB2R). Eur J Med Chem 2020; 188:112037. [PMID: 31954990 DOI: 10.1016/j.ejmech.2020.112037] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/17/2019] [Accepted: 01/03/2020] [Indexed: 12/28/2022]
Abstract
The Cannabinoid 2 receptor, CB2R, belonging to the endocannabinoid system, ECS, is involved in the first steps of neurodegeneration and cancer evolution and progression and thus its modulation may be exploited in the therapeutic and diagnostic fields. However, CB2Rs distribution and signaling pathways in physiological and pathological conditions are still controversial mainly because of the lack of reliable diagnostic tools. With the aim to produce green and safe systems to detect CB2R, we designed a series of fluorescent ligands with three different green fluorescent moieties (4-dimethylaminophthalimide, 4-DMAP, 7-nitro-4-yl-aminobenzoxadiazole, NBD, and Fluorescein-thiourea, FTU) linked to the N1-position of the CB2R pharmacophore N-adamantyl-4-oxo-1,4-dihydroquinoline-3-carboxamide through polymethylene chains. Compound 28 emerged for its compromise between good pharmacodynamic properties (CB2R Ki = 130 nM and no affinity vs the other subtype CB1R) and optimal fluorescent spectroscopic properties. Therefore, compound 28 was studied through FACS (saturation and competitive binding studies) and fluorescence microscopy (visualization and competitive binding) in engineered cells (CB2R-HEK293 cells) and in diverse tumour cells. The fluoligand binding assays were successfully set up, and affinity values for the two reference compounds GW405833 and WIN55,212-2, comparable to the values obtained by radioligand binding assays, were obtained. Fluoligand 28 also allowed the detection of the presence and quantification of the CB2R in the same cell lines. The interactions of compound 28 within the CB2R binding site were also investigated by molecular docking simulations, and indications for the improvement of the CB2R affinity of this class of compounds were provided. Overall, the results obtained through these studies propose compound 28 as a safe and green alternative to the commonly used radioligands for in vitro investigations.
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Attili B, Celen S, Ahamed M, Koole M, Haute CVD, Vanduffel W, Bormans G. Preclinical evaluation of [ 18 F]MA3: a CB 2 receptor agonist radiotracer for PET. Br J Pharmacol 2019; 176:1481-1491. [PMID: 30588600 DOI: 10.1111/bph.14564] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 10/31/2018] [Accepted: 11/16/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Non-invasive in vivo imaging of cannabinoid CB2 receptors using PET is pursued to study neuroinflammation. The purpose of this study is to evaluate the in vivo binding specificity of [18 F]MA3, a CB2 receptor agonist, in a rat model with local overexpression of human (h) CB2 receptors. METHODS [18 F]MA3 was produced with good radiochemical yield and radiochemical purity. The radiotracer was evaluated in rats with local overexpression of hCB2 receptors and in a healthy non-human primate using PET. KEY RESULTS Ex vivo autoradiography demonstrated CB2 -specific binding of [18 F]MA3 in rat hCB2 receptor vector injected striatum. In a PET study, increased tracer binding in the hCB2 receptor vector-injected striatum compared to the contralateral control vector-injected striatum was observed. Binding in hCB2 receptor vector-injected striatum was blocked with a structurally non-related CB2 receptor inverse agonist, and a displacement study confirmed the reversibility of tracer binding. This study identified the utility of mutated inactive vector model for evaluation of CB2 receptor agonist PET tracers. [18 F]MA3 PET scans in the non-human primate showed good uptake and fast washout from brain, but no CB2 receptor-specific binding was observed. CONCLUSION AND IMPLICATIONS Evaluation of [18 F]MA3 in a rat model with local overexpression of hCB2 receptors showed CB2 receptor-specific and reversible tracer binding. [18 F]MA3 showed good brain uptake and subsequent washout in a healthy non-human primate, but no specific binding was observed. Further clinical evaluation of [18 F]MA3 in patients with neuroinflammation is warranted. LINKED ARTICLES This article is part of a themed section on 8th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc.
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Affiliation(s)
- Bala Attili
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Sofie Celen
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Muneer Ahamed
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Michel Koole
- Department of Nuclear Medicine and Molecular Imaging, UZ Gasthuisberg, Leuven, Belgium
| | - Chris Van Den Haute
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, KU Leuven, Leuven, Belgium.,Leuven Viral Vector Core, Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Wim Vanduffel
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
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11
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Fantoni ER, Dal Ben D, Falzoni S, Di Virgilio F, Lovestone S, Gee A. Design, synthesis and evaluation in an LPS rodent model of neuroinflammation of a novel 18F-labelled PET tracer targeting P2X7. EJNMMI Res 2017; 7:31. [PMID: 28374288 PMCID: PMC5378566 DOI: 10.1186/s13550-017-0275-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 03/08/2017] [Indexed: 01/08/2023] Open
Abstract
Background The P2X7 receptor has been shown to play a fundamental role in the initiation and sustenance of the inflammatory cascade. The development of a novel fluorine-18 PET tracer superior and with a longer half-life to those currently available is a promising step towards harnessing the therapeutic and diagnostic potential offered by this target. Inspired by the known antagonist A-804598, the present study outlines the design via molecular docking, synthesis and biological evaluation of the novel P2X7 tracer [18F]EFB. The tracer was radiolabelled via a three-step procedure, in vitro binding assessed in P2X7-transfected HEK293 and in B16 cells by calcium influx assays and an initial preclinical evaluation was performed in a lipopolysaccharide (LPS)-injected rat model of neuroinflammation. Results The novel tracer [18F]EFB was synthesised in 210 min in 3–5% decay-corrected radiochemical yield (DC RCY), >99% radiochemical purity (RCP) and >300 GBq/μmol and fully characterised. Functional assays showed that the compound binds with nM Ki to human, rat and mouse P2X7 receptors. In vivo, [18F]EFB displayed a desirable distribution profile, and while it showed low blood–brain barrier penetration, brain uptake was quantifiable and displayed significantly higher mean longitudinal uptake in inflamed versus control rat CNS regions. Conclusions [18F]EFB demonstrates strong in vitro affinity to human and rodent P2X7 and limited yet quantifiable BBB penetration. Considering the initial promising in vivo data in an LPS rat model with elevated P2X7 expression, this work constitutes an important step in the development of a radiotracer useful for the diagnosis and monitoring of clinical disorders with associated neuroinflammatory processes. Electronic supplementary material The online version of this article (doi:10.1186/s13550-017-0275-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Enrico Raffaele Fantoni
- Department of Imaging Sciences and Biomedical Engineering, King's College London, St Thomas' Hospital, 4th floor Lambeth Wing, SE1 7EH, London, UK
| | - Diego Dal Ben
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino 1, 62032, Camerino, MC, Italy
| | - Simonetta Falzoni
- Prof Francesco Di Virgilio and Dr Simonetta Falzoni, Dipartimento di Morfologia, Chirurgia e Medicina Sperimentale, Sezione di Patologia, Oncologia e Biologia Sperimentale, University of Ferrara, Ferrara, Italy
| | - Francesco Di Virgilio
- Prof Francesco Di Virgilio and Dr Simonetta Falzoni, Dipartimento di Morfologia, Chirurgia e Medicina Sperimentale, Sezione di Patologia, Oncologia e Biologia Sperimentale, University of Ferrara, Ferrara, Italy
| | - Simon Lovestone
- Department of Psychiatry, Warneford Hospital, University of Oxford, Warneford Lane, Oxford, OX3 7JX, UK
| | - Antony Gee
- Department of Imaging Sciences and Biomedical Engineering, King's College London, St Thomas' Hospital, 4th floor Lambeth Wing, SE1 7EH, London, UK.
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12
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van der Born D, Pees A, Poot AJ, Orru RVA, Windhorst AD, Vugts DJ. Fluorine-18 labelled building blocks for PET tracer synthesis. Chem Soc Rev 2017; 46:4709-4773. [DOI: 10.1039/c6cs00492j] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review presents a comprehensive overview of the synthesis and application of fluorine-18 labelled building blocks since 2010.
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Affiliation(s)
- Dion van der Born
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Anna Pees
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Alex J. Poot
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Romano V. A. Orru
- Department of Chemistry and Pharmaceutical Sciences and Amsterdam Institute for Molecules
- Medicines & Systems (AIMMS)
- VU University Amsterdam
- Amsterdam
- The Netherlands
| | - Albert D. Windhorst
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Danielle J. Vugts
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
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13
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Ahamed M, van Veghel D, Ullmer C, Van Laere K, Verbruggen A, Bormans GM. Synthesis, Biodistribution and In vitro Evaluation of Brain Permeable High Affinity Type 2 Cannabinoid Receptor Agonists [ 11C]MA2 and [ 18F]MA3. Front Neurosci 2016; 10:431. [PMID: 27713686 PMCID: PMC5031696 DOI: 10.3389/fnins.2016.00431] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 09/06/2016] [Indexed: 12/22/2022] Open
Abstract
The type 2 cannabinoid receptor (CB2) is a member of the endocannabinoid system and is known for its important role in (neuro)inflammation. A PET-imaging agent that allows in vivo visualization of CB2 expression may thus allow quantification of neuroinflammation. In this paper, we report the synthesis, radiosynthesis, biodistribution and in vitro evaluation of a carbon-11 ([11C]MA2) and a fluorine-18 ([18F]MA3) labeled analog of a highly potent N-arylamide oxadiazole CB2 agonist (EC50 = 0.015 nM). MA2 and MA3 behaved as potent CB2 agonist (EC50: 3 nM and 0.1 nM, respectively) and their in vitro binding affinity for hCB2 was found to be 87 nM and 0.8 nM, respectively. Also MA3 (substituted with a fluoro ethyl group) was found to have higher binding affinity and EC50 values when compared to the originally reported trifluoromethyl analog 12. [11C]MA2 and [18F]MA3 were successfully synthesized with good radiochemical yield, high radiochemical purity and high specific activity. In mice, both tracers were efficiently cleared from blood and all major organs by the hepatobiliary pathway and importantly these compounds showed high brain uptake. In conclusion, [11C]MA2 and [18F]MA3 are shown to be high potent CB2 agonists with good brain uptake, these favorable characteristics makes them potential PET probes for in vivo imaging of brain CB2 receptors. However, in view of its higher affinity and selectivity, further detailed evaluation of MA3 as a PET tracer for CB2 is warranted.
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Affiliation(s)
- Muneer Ahamed
- Laboratory for Radiopharmacy, KU Leuven Leuven, Belgium
| | | | - Christoph Ullmer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd Basel, Switzerland
| | - Koen Van Laere
- Division of Nuclear Medicine, University Hospital and KU Leuven Leuven, Belgium
| | | | - Guy M Bormans
- Laboratory for Radiopharmacy, KU Leuven Leuven, Belgium
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14
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Slavik R, Müller Herde A, Haider A, Krämer SD, Weber M, Schibli R, Ametamey SM, Mu L. Discovery of a fluorinated 4-oxo-quinoline derivative as a potential positron emission tomography radiotracer for imaging cannabinoid receptor type 2. J Neurochem 2016; 138:874-86. [PMID: 27385045 DOI: 10.1111/jnc.13716] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 11/28/2022]
Abstract
The cannabinoid receptor type 2 (CB2) is part of the endocannabinoid system and has gained growing attention in recent years because of its important role in neuroinflammatory/neurodegenerative diseases. Recently, we reported on a carbon-11 labeled 4-oxo-quinoline derivative, designated RS-016, as a promising radiotracer for imaging CB2 using PET. In this study, three novel fluorinated analogs of RS-016 were designed, synthesized, and pharmacologically evaluated. The results of our efforts led to the identification of N-(1-adamantyl)-1-(2-(2-fluoroethoxy)ethyl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxamide (RS-126) as the most potent candidate for evaluation as a CB2 PET ligand. [(18) F]RS-126 was obtained in ≥ 99% radiochemical purity with an average specific radioactivity of 98 GBq/μmol at the end of the radiosynthesis. [(18) F]RS-126 showed a logD7.4 value of 1.99 and is stable in vitro in rat and human plasma over 120 min, whereas 55% intact parent compound was found in vivo in rat blood plasma at 10 min post injection. In vitro autoradiographic studies with CB2-positive rat spleen tissue revealed high and blockable binding which was confirmed in in vivo displacement experiments with rats by dynamic PET imaging. Ex vivo biodistribution studies confirmed accumulation of [(18) F]RS-126 in rat spleen with a specificity of 79% under blocking conditions. The moderate elevated CB2 levels in LPS-treated mice brain did not permit the detection of CB2 by [(18) F]RS-126 using PET imaging. In summary, [(18) F]RS-126 demonstrated high specificity toward CB2 receptor in vitro and in vivo and is a promising radioligand for imaging CB2 receptor expression. Cannabinoid receptor type 2 (CB2) is an interesting target for PET imaging. Specific binding of [(18) F]RS-126 in CB2-positive spleen tissue (white arrow head) was confirmed in in vivo displacement experiments with rats. Time activity curve of [(18) F]RS-126 in the spleen after the addition of GW405833 (CB2 specific ligand, green) demonstrates faster radiotracer elimination (blue) compared to the tracer only (red).
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Affiliation(s)
- Roger Slavik
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | | | - Ahmed Haider
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Stefanie D Krämer
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Markus Weber
- Neuromuscular Diseases Unit/ALS Clinic, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Roger Schibli
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Simon M Ametamey
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland.
| | - Linjing Mu
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland. .,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
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15
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Radiopharmaceuticals for PET imaging of neuroinflammation. MEDECINE NUCLEAIRE-IMAGERIE FONCTIONNELLE ET METABOLIQUE 2016. [DOI: 10.1016/j.mednuc.2016.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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16
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17
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Saccomanni G, Pascali G, Carlo SD, Panetta D, De Simone M, Bertini S, Burchielli S, Digiacomo M, Macchia M, Manera C, Salvadori PA. Design, synthesis and preliminary evaluation of (18)F-labelled 1,8-naphthyridin- and quinolin-2-one-3-carboxamide derivatives for PET imaging of CB2 cannabinoid receptor. Bioorg Med Chem Lett 2015; 25:2532-5. [PMID: 25956416 DOI: 10.1016/j.bmcl.2015.04.055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 04/15/2015] [Accepted: 04/17/2015] [Indexed: 10/23/2022]
Abstract
In the present work, we report the synthesis of new aryliodonium salts used as precursors of single-stage nucleophilic (18)F radiofluorination. The corresponding unlabelled fluorinated derivatives showed to be CB2 cannabinoid receptor specific ligands, with Ki values in the low nanomolar range and high CB2/CB1 selectivity. The radiolabelled compound [(18)F]CB91, was successfully formulated for in vivo administration, and its preliminary biodistribution was assessed with microPET/CT. This tracer presented a reasonable in vivo stability and a preferential extraction in the tissues that constitutionally express CB2 cannabinoid receptor. The results obtained indicate [(18)F]CB91 as a possible candidate marker of CB2 cannabinoid receptor distribution. This study would open the way to further validation of this tracer for assessing pathologies for which the expression of this receptor is modified.
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Affiliation(s)
- Giuseppe Saccomanni
- Dipartimento di Farmacia, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Giancarlo Pascali
- CNR Istituto di Fisiologia Clinica, Via Moruzzi, 1, 56124 Pisa, Italy; ANSTO LifeSciences, PO Box M34, Camperdown 2050, Australia
| | - Sara Del Carlo
- Dipartimento di Farmacia, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Daniele Panetta
- CNR Istituto di Fisiologia Clinica, Via Moruzzi, 1, 56124 Pisa, Italy
| | | | - Simone Bertini
- Dipartimento di Farmacia, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | | | - Maria Digiacomo
- Dipartimento di Farmacia, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Marco Macchia
- Dipartimento di Farmacia, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Clementina Manera
- Dipartimento di Farmacia, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy.
| | - Piero A Salvadori
- CNR Istituto di Fisiologia Clinica, Via Moruzzi, 1, 56124 Pisa, Italy
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18
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Yrjölä S, Sarparanta M, Airaksinen AJ, Hytti M, Kauppinen A, Pasonen-Seppänen S, Adinolfi B, Nieri P, Manera C, Keinänen O, Poso A, Nevalainen TJ, Parkkari T. Synthesis, in vitro and in vivo evaluation of 1,3,5-triazines as cannabinoid CB2 receptor agonists. Eur J Pharm Sci 2014; 67:85-96. [PMID: 25447744 DOI: 10.1016/j.ejps.2014.11.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/01/2014] [Accepted: 11/06/2014] [Indexed: 11/28/2022]
Abstract
The cannabinoid receptors type 2 (CBR2) are attractive therapeutic targets of the endocannabinoid signaling system (ECS) as they are not displaying the undesired psychotropic and cardiovascular side-effects seen with cannabinoid receptor type 1 (CB1R) agonists. In continuation of our previous work on 2,4,6-trisubstituted 1,3,5-triazines as potent CB2 agonists, we synthesized an additional series of more polar analogues (1-10), which were found to possess high CB2R agonist activity with enhanced water solubility. The most potent compound in the series was N-(adamantan-1-yl)-4-ethoxy-6-(4-(2-fluoroethyl)piperazin-1-yl)-1,3,5-triazin-2-amine (9) with EC50 value of 0.60nM. To further evaluate the biological effects of the compounds, the selected compounds were tested in vitro against four different cell lines. A human retinal pigment epithelial cell line (ARPE-19) was used to evaluate the cytotoxicity of the compounds whereas an androgen-sensitive human prostate adenocarcinoma cell line (LNCaP), a Jurkat leukemia cell line and a C8161 melanoma cell line were used to assess the antiproliferative activity of the compounds. The most interesting results were obtained for N-(adamantan-1-yl)-4-ethoxy-6-(4-methylpiperazin-1-yl)-1,3,5-triazin-2-amine (6), which induced cell viability decrease in prostate and leukemia cell lines, and diminished proliferation of C8161 melanoma cells. The results could be reversed in leukemia cells with the selective CB2R antagonist AM630, whereas in prostate cells the AM630 induced a significant cell viability decrease with a mechanism probably unlinked to CB2 cannabinoid receptor. The antiproliferative effect of 6 on the melanoma cells seemed not to be mediated via the CB1R or CB2R. No cytotoxicity was detected against ARPE-19 cell line at concentrations of 1 and 10μM for compound 6. However, at 30μM concentration the compound 6 decreased the cell viability. Finally, in order to estimate in vivo behavior of these compounds, (18)F labeled PET ligand, N-cyclopentyl-4-ethoxy-6-(4-(2-fluoro-18-ethyl)piperazin-1-yl)-1,3,5-triazin-2-amine ([(18)F]5), was synthesized and its biodistribution was determined in healthy male Sprague-Dawley rats. As a result, the tracer showed a rapid (<15min) elimination in urine accompanied by a slower excretion via the hepatobiliary route. In conclusion, we further demonstrated that 1,3,5-triazine scaffold serves as a suitable template for the design of highly potent CB2R agonists with reasonable water solubility properties. The compounds may be useful when studying the role of the endocannabinoid system in different diseases. The triazine scaffold is also a promising candidate for the development of new CB2R PET ligands.
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Affiliation(s)
- Sari Yrjölä
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
| | - Mirkka Sarparanta
- Laboratory of Radiochemistry, Department of Chemistry, PO Box 55, FI-00014 University of Helsinki, Finland
| | - Anu J Airaksinen
- Laboratory of Radiochemistry, Department of Chemistry, PO Box 55, FI-00014 University of Helsinki, Finland
| | - Maria Hytti
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O.B. 1627, FI-70211 Kuopio, Finland
| | - Anu Kauppinen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O.B. 1627, FI-70211 Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, P.O.B 100, FI-70029 KYS, Finland
| | - Sanna Pasonen-Seppänen
- School of Medicine, Institute of Biomedicine, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Barbara Adinolfi
- Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino, FI, Italy; Department of Pharmacy, University of Pisa, Via Bonanno 6, 56100 Pisa, PI, Italy
| | - Paola Nieri
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56100 Pisa, PI, Italy
| | - Clementina Manera
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56100 Pisa, PI, Italy
| | - Outi Keinänen
- Laboratory of Radiochemistry, Department of Chemistry, PO Box 55, FI-00014 University of Helsinki, Finland
| | - Antti Poso
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland; Division of Translational Gastrointestinal Oncology, Dept. of Internal Medicine I, University Hospital Tuebingen, Otfried-Mueller-Strasse 10, 72076 Tuebingen, Germany
| | - Tapio J Nevalainen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Teija Parkkari
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
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Amhaoul H, Staelens S, Dedeurwaerdere S. Imaging brain inflammation in epilepsy. Neuroscience 2014; 279:238-52. [DOI: 10.1016/j.neuroscience.2014.08.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/27/2014] [Accepted: 08/27/2014] [Indexed: 01/15/2023]
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20
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Ciccarelli O, Barkhof F, Bodini B, Stefano ND, Golay X, Nicolay K, Pelletier D, Pouwels PJW, Smith SA, Wheeler-Kingshott CAM, Stankoff B, Yousry T, Miller DH. Pathogenesis of multiple sclerosis: insights from molecular and metabolic imaging. Lancet Neurol 2014; 13:807-22. [DOI: 10.1016/s1474-4422(14)70101-2] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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21
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Rotstein BH, Stephenson NA, Vasdev N, Liang SH. Spirocyclic hypervalent iodine(III)-mediated radiofluorination of non-activated and hindered aromatics. Nat Commun 2014; 5:4365. [PMID: 25007318 DOI: 10.1038/ncomms5365] [Citation(s) in RCA: 181] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/10/2014] [Indexed: 01/21/2023] Open
Abstract
Fluorine-18 (t½=109.7 min) is the most commonly used isotope to prepare radiopharmaceuticals for molecular imaging by positron emission tomography (PET). Nucleophilic aromatic substitution reactions of suitably activated (electron-deficient) aromatic substrates with no-carrier-added [(18)F]fluoride ion are routinely carried out in the synthesis of radiotracers in high specific activities. Despite extensive efforts to develop a general (18)F-labelling technique for non-activated arenes there is an urgent and unmet need to achieve this goal. Here we describe an effective solution that relies on the chemistry of spirocyclic hypervalent iodine(III) complexes, which serve as precursors for rapid, one-step regioselective radiofluorination with [(18)F]fluoride. This methodology proves to be efficient for radiolabelling a diverse range of non-activated functionalized arenes and heteroarenes, including arene substrates bearing electron-donating groups, bulky ortho functionalities, benzylic substituents and meta-substituted electron-withdrawing groups. Polyfunctional molecules and a range of previously elusive (18)F-labelled building blocks, compounds and radiopharmaceuticals are synthesized.
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Affiliation(s)
- Benjamin H Rotstein
- 1] Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA [2]
| | - Nickeisha A Stephenson
- 1] Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA [2]
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
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22
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Mu L, Slavik R, Müller A, Popaj K, Cermak S, Weber M, Schibli R, Krämer SD, Ametamey SM. Synthesis and Preliminary Evaluation of a 2-Oxoquinoline Carboxylic Acid Derivative for PET Imaging the Cannabinoid Type 2 Receptor. Pharmaceuticals (Basel) 2014; 7:339-52. [PMID: 24662272 PMCID: PMC3978495 DOI: 10.3390/ph7030339] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/21/2014] [Accepted: 02/27/2014] [Indexed: 11/27/2022] Open
Abstract
Cannabinoid receptor subtype 2 (CB2) has been shown to be up-regulated in activated microglia and therefore plays an important role in neuroinflammatory and neurodegenerative diseases such as multiple sclerosis, amyotrophic lateral sclerosis and Alzheimer’s disease. The CB2 receptor is therefore considered as a very promising target for therapeutic approaches as well as for imaging. A promising 2-oxoquinoline derivative designated KP23 was synthesized and radiolabeled and its potential as a ligand for PET imaging the CB2 receptor was evaluated. [11C]KP23 was obtained in 10%–25% radiochemical yield (decay corrected) and 99% radiochemical purity. It showed high stability in phosphate buffer, rat and mouse plasma. In vitro autoradiography of rat and mouse spleen slices, as spleen expresses a high physiological expression of CB2 receptors, demonstrated that [11C]KP23 exhibits specific binding towards CB2. High spleen uptake of [11C]KP23 was observed in dynamic in vivo PET studies with Wistar rats. In conclusion, [11C]KP23 showed promising in vitro and in vivo characteristics. Further evaluation with diseased animal model which has higher CB2 expression levels in the brain is warranted.
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Affiliation(s)
- Linjing Mu
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Department of Nuclear Medicine, University Hospital Zürich, CH-8091 Zürich, Switzerland.
| | - Roger Slavik
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Adrienne Müller
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Kasim Popaj
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Department of Nuclear Medicine, University Hospital Zürich, CH-8091 Zürich, Switzerland
| | - Stjepko Cermak
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Markus Weber
- Neuromuscular Diseases Unit/ALS Clinic, Kantonsspital St. Gallen, CH-9007 St. Gallen, Switzerland
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Department of Nuclear Medicine, University Hospital Zürich, CH-8091 Zürich, Switzerland
| | - Stefanie D Krämer
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Simon M Ametamey
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
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23
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Ahmad R, Koole M, Evens N, Serdons K, Verbruggen A, Bormans G, Van Laere K. Whole-body biodistribution and radiation dosimetry of the cannabinoid type 2 receptor ligand [11C]-NE40 in healthy subjects. Mol Imaging Biol 2014; 15:384-90. [PMID: 23508466 DOI: 10.1007/s11307-013-0626-y] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE The type 2 cannabinoid receptor (CB2R) is part of the human endocannabinoid system and is involved in central and peripheral inflammatory processes. In vivo imaging of the CB2R would allow study of several (neuro)inflammatory disorders. In this study we have investigated the safety and tolerability of [11C]-NE40, a CB2R positron emission tomography (PET) ligand, in healthy human male subjects and determined its biodistribution and radiation dosimetry. PROCEDURE Six healthy male subjects (age 20-65 years) underwent a dynamic series of nine whole-body PET/CT scans for up to 140 min, after injection of an average bolus of 286 MBq of [11C]-NE40. Organ absorbed and total effective doses were calculated through OLINDA. RESULTS [11C]-NE40 showed high initial uptake in the spleen and a predominant hepatobiliary excretion. In the brain, rapid uptake and swift washout were seen. Organ absorbed doses were largest for the small intestine and liver, with 15.6 and 11.5 μGy/MBq, respectively. The mean effective dose was 3.64±0.81 μSv/MBq. There were no changes with aging observed. No adverse events were encountered. CONCLUSIONS This first-in-man study of [11C]-NE40 showed an expected biodistribution compatible with lymphoid tissue uptake and appropriate fast brain kinetics in the healthy human brain, underscoring the potential of this tracer for further application in central and peripheral inflammation imaging. The effective dose is within the typical expected range for 11C ligands.
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Affiliation(s)
- Rawaha Ahmad
- Division of Nuclear Medicine, University Hospital Leuven, Herestraat 49, 3000, Leuven, Belgium.
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24
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Holland JP, Liang SH, Rotstein BH, Collier TL, Stephenson NA, Greguric I, Vasdev N. Alternative approaches for PET radiotracer development in Alzheimer's disease: imaging beyond plaque. J Labelled Comp Radiopharm 2013; 57:323-31. [PMID: 24327420 DOI: 10.1002/jlcr.3158] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/29/2013] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD) and related dementias show increasing clinical prevalence, yet our understanding of the etiology and pathobiology of disease-related neurodegeneration remains limited. In this regard, noninvasive imaging with radiotracers for positron emission tomography (PET) presents a unique tool for quantifying spatial and temporal changes in characteristic biological markers of brain disease and for assessing potential drug efficacy. PET radiotracers targeting different protein markers are being developed to address questions pertaining to the molecular and/or genetic heterogeneity of AD and related dementias. For example, radiotracers including [(11) C]-PiB and [(18) F]-AV-45 (Florbetapir) are being used to measure the density of Aβ-plaques in AD patients and to interrogate the biological mechanisms of disease initiation and progression. Our focus is on the development of novel PET imaging agents, targeting proteins beyond Aβ-plaques, which can be used to investigate the broader mechanism of AD pathogenesis. Here, we present the chemical basis of various radiotracers which show promise in preclinical or clinical studies for use in evaluating the phenotypic or biochemical characteristics of AD. Radiotracers for PET imaging neuroinflammation, metal ion association with Aβ-plaques, tau protein, cholinergic and cannabinoid receptors, and enzymes including glycogen-synthase kinase-3β and monoamine oxidase B amongst others, and their connection to AD are highlighted.
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Affiliation(s)
- Jason P Holland
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Department of Radiology, Harvard Medical School, 55 Fruit St., White 427, Boston, Massachusetts, 02114, USA; Life Sciences, Australian Nuclear Science and Technology Organisation, Kirrawee, New South Wales, 2232, Australia
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25
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Lueg C, Schepmann D, Günther R, Brust P, Wünsch B. Development of fluorinated CB2 receptor agonists for PET studies. Bioorg Med Chem 2013; 21:7481-98. [DOI: 10.1016/j.bmc.2013.09.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/12/2013] [Accepted: 09/16/2013] [Indexed: 10/26/2022]
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26
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Zhang S, Shao P, Bai M. In vivo type 2 cannabinoid receptor-targeted tumor optical imaging using a near infrared fluorescent probe. Bioconjug Chem 2013; 24:1907-16. [PMID: 24094147 DOI: 10.1021/bc400328m] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The type 2 cannabinoid receptor (CB2R) plays a vital role in carcinogenesis and progression and is emerging as a therapeutic target for cancers. However, the exact role of CB2R in cancer progression and therapy remains unclear. This has driven the increasing efforts to study CB2R and cancers using molecular imaging tools. In addition, many types of cancers overexpress CB2R, and the expression levels of CB2R appear to be associated with tumor aggressiveness. Such upregulation of the receptor in cancer cells provides opportunities for CB2R-targeted imaging with high contrast and for therapy with low side effects. In the present study, we report the first in vivo tumor-targeted optical imaging using a novel CB2R-targeted near-infrared probe. In vitro cell fluorescent imaging and a competitive binding assay indicated specific binding of NIR760-mbc94 to CB2R in CB2-mid delayed brain tumor (DBT) cells. NIR760-mbc94 also preferentially labeled CB2-mid DBT tumors in vivo, with a 3.7-fold tumor-to-normal contrast enhancement at 72 h postinjection, whereas the fluorescence signal from the tumors of the mice treated with NIR760 free dye was nearly at the background level at the same time point. SR144528, a CB2R competitor, significantly inhibited tumor uptake of NIR760-mbc94, indicating that NIR760-mbc94 binds to CB2R specifically. In summary, NIR760-mbc94 specifically binds to CB2R in vitro and in vivo and appears to be a promising molecular tool that may have great potential for use in diagnostic imaging of CB2R-positive cancers and therapeutic monitoring as well as in elucidating the role of CB2R in cancer progression and therapy.
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Affiliation(s)
- Shaojuan Zhang
- Molecular Imaging Laboratory, Department of Radiology, University of Pittsburgh , Pittsburgh, Pennsylvania 15219, United States
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Teodoro R, Moldovan RP, Lueg C, Günther R, Donat CK, Ludwig FA, Fischer S, Deuther-Conrad W, Wünsch B, Brust P. Radiofluorination and biological evaluation of N-aryl-oxadiazolyl-propionamides as potential radioligands for PET imaging of cannabinoid CB2 receptors. Org Med Chem Lett 2013; 3:11. [PMID: 24063584 PMCID: PMC3856494 DOI: 10.1186/2191-2858-3-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/15/2013] [Indexed: 11/10/2022] Open
Abstract
Background The level of expression of cannabinoid receptor type 2 (CB2R) in healthy and diseased brain has not been fully elucidated. Therefore, there is a growing interest to assess the regional expression of CB2R in the brain. Positron emission tomography (PET) is an imaging technique, which allows quantitative monitoring of very low amounts of radiolabelled compounds in living organisms at high temporal and spatial resolution and, thus, has been widely used as a diagnostic tool in nuclear medicine. Here, we report on the radiofluorination of N-aryl-oxadiazolyl-propionamides at two different positions in the lead structure and on the biological evaluation of the potential of the two tracers [18F]1 and [18F]2 as CB2 receptor PET imaging agents. Results High binding affinity and specificity towards CB2 receptors of the lead structure remained unaffected by the structural changes such as the insertion of the aliphatic and aromatic fluorine in the selected labelling sites of 1 and 2. Aliphatic and aromatic radiofluorinations were optimized, and [18F]1 and [18F]2 were achieved in radiochemical yields of ≥30% with radiochemical purities of ≥98% and specific activities of 250 to 450 GBq/μmol. Organ distribution studies in female CD1 mice revealed that both radiotracers cross the blood–brain barrier (BBB) but undergo strong peripheral metabolism. At 30 min after injection, unmetabolized [18F]1 and [18F]2 accounted for 60% and 2% as well as 68% and 88% of the total activity in the plasma and brain, respectively. The main radiometabolite of [18F]2 could be identified as the free acid [18F]10, which has no affinity towards the CB1 and CB2 receptors but can cross the BBB. Conclusions N-aryl-oxadiazolyl-propionamides can successfully be radiolabelled with 18F at different positions. Fluorine substitution at these positions did not affect affinity and specificity towards CB2R. Despite a promising in vitro behavior, a rather rapid peripheral metabolism of [18F]1 and [18F]2 in mice and the generation of brain permeable radiometabolites hamper the application of these radiotracers in vivo. However, it is expected that future synthetic modification aiming at a replacement of metabolically susceptible structural elements of [18F]1 and [18F]2 will help to elucidate the potential of this class of compounds for CB2R PET studies.
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Affiliation(s)
- Rodrigo Teodoro
- Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 58-62, 48149 Münster, Germany.
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Mu L, Bieri D, Slavik R, Drandarov K, Müller A, Cermak S, Weber M, Schibli R, Krämer SD, Ametamey SM. Radiolabeling and in vitro /in vivo evaluation of N-(1-adamantyl)-8-methoxy-4-oxo-1-phenyl-1,4-dihydroquinoline-3-carboxamide as a PET probe for imaging cannabinoid type 2 receptor. J Neurochem 2013; 126:616-24. [PMID: 23795580 DOI: 10.1111/jnc.12354] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/12/2013] [Accepted: 06/19/2013] [Indexed: 11/30/2022]
Abstract
The cannabinoid type 2 (CB2) receptor plays an important role in neuroinflammatory and neurodegenerative diseases such as multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer’s disease and is therefore a very promising target for therapeutic approaches as well as for imaging. Based on the literature, we identified one 4-oxoquinoline derivative(designated KD2) as the lead structure. It was synthesized, radiolabeled and evaluated as a potential imaging tracer for CB2. [11C]KD2 was obtained in 99% radiochemical purity.Moderate blood–brain barrier (BBB) passage was predicted for KD2 from an in vitro transport assay with P-glycoprotein-transfected Madin Darby canine kidney cells. No efflux of KD2 by P-glycoprotein was detected. In vitro autoradiography of rat and mouse spleen slices demonstrated that [11C]KD2 exhibits high specific binding towards CB2. High spleen uptake of [11C]KD2 was observed in dynamic positron emission tomography(PET) studies with Wistar rats and its specificity was confirmed by displacement study with a selective CB2 agonist, GW405833. A pilot autoradiography study with post-mortem spinal cord slices from amyotrophic lateral sclerosis (ALS)patients with [11C]KD2 suggested the presence of CB2 receptors under disease conditions. Specificity of [11C]KD2 binding could also be demonstrated on these human tissues. In conclusion, [11C]KD2 shows good in vitro and in vivo properties as a potential PET tracer for CB2.
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Affiliation(s)
- Linjing Mu
- Department of Nuclear Medicine, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, University Hospital Zürich, Zürich, Switzerland
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