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Li W, Zhang X, Zhou J, Di X, Huang D, Ma J, Zhou K, Zhang J, Wang L, Fu H, Cui M. Structure-based discovery of a 4,5-Dihydropyrazole-cored PET ligand for imaging of receptor-interacting serine/threonine-protein kinase 1 (RIPK1) in the brain. Eur J Med Chem 2024; 279:116803. [PMID: 39255641 DOI: 10.1016/j.ejmech.2024.116803] [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] [Received: 06/24/2024] [Revised: 08/24/2024] [Accepted: 08/25/2024] [Indexed: 09/12/2024]
Abstract
Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) regulates programmed cell death and inflammation, contributing to a wide range of human pathologies, including inflammatory disorders, neurodegenerative conditions, and cancer. Despite this, no RIPK1 positron emission tomography (PET) ligand with significant in vivo specificity has been reported to date. In this work, we designed and synthesized a new family of dihydropyrazole-cored ligands suitable for 18F-labeling at the late stage. Among these, WL8 showed a strong binding affinity to RIPK1 (EC50 = 19.9 nM, Kd = 25 nM) and was successfully labeled with 18F in the 6-position of pyridine ring, yielding a high radiochemistry yield of 27.9 % (decay-corrected) and a high molar activity of 18.8-31.2 GBq/μmol. In in vitro autoradiography, [18F]WL8 showed some specific binding in the brain sections of rats and lipopolysaccharide (LPS) model mice. Preliminary PET studies in rat brains revealed that [18F]WL8 could efficiently penetrate the blood-brain barrier and was rapidly washed out. As anticipated, [18F]WL8 exhibited a high initial uptake (brain2min = 4.80 % ID/g) in mouse brains, followed by a rapid washout (brain60min = 0.14 % ID/g), although no clear specific binding to RIPK1 was observed. Moderate in vivo stability was noted for [18F]WL8 in mouse brains with 35.2 % of the parent fraction remaining after 30 min post-administration. Altogether, our work broadens the landscape and offers a new chemotype for RIPK1 PET ligand development.
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Affiliation(s)
- Wanqing Li
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, PR China
| | - Xiaojun Zhang
- Department of Nuclear Medicine, Chinese PLA General Hospital, Beijing, 100853, PR China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, PR China
| | - Xuan Di
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, PR China
| | - Donglan Huang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, PR China
| | - Jie Ma
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, PR China
| | - Kaixiang Zhou
- Center for Advanced Materials Research & Faculty of Arts and Sciences, Beijing Normal University, Zhuhai, 519087, PR China
| | - Jinming Zhang
- Department of Nuclear Medicine, Chinese PLA General Hospital, Beijing, 100853, PR China.
| | - Lu Wang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, PR China.
| | - Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, PR China.
| | - Mengchao Cui
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, PR China; Center for Advanced Materials Research & Faculty of Arts and Sciences, Beijing Normal University, Zhuhai, 519087, PR China
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2
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Jiang M, Ellin NR, Telu S, Mungalpara M, Wu X, Li Z, Lu S, Pike VW. Difluoromethoxide Is a Strong Leaving Group in the Photoredox Deoxyradiofluorination of 2-Phenylpyridines. J Org Chem 2024; 89:13768-13773. [PMID: 39258625 DOI: 10.1021/acs.joc.4c01505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
A 2-phenyl-3-difluoromethoxy-pyridinyl moiety features in potent phosphodiesterase 4D inhibitors that are considered to be candidate radiotracers for positron emission tomography if they are labeled with fluorine-18. Fluorine-18 could be installed as desired at the 3'-phenyl position with acridinium-mediated photoredox radiodeoxyfluorination in homologues bearing variously substituted 3'-aryloxy groups. However, a distal 3-difluoromethoxide (-OCHF2) group strongly competes as a leaving group, especially when an electron-deficient aryloxy group is present at position 3'. A yield of up to 50% may occur without observable 19F for 18F exchange.
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Affiliation(s)
- Meijuan Jiang
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland 20892-1003, United States
| | - Nicholas R Ellin
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland 20892-1003, United States
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland 20892-1003, United States
| | - Maulik Mungalpara
- Biomedical Research Imaging Center, Department of Radiology and UNC Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, United States
| | - Xuedan Wu
- Biomedical Research Imaging Center, Department of Radiology and UNC Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, United States
| | - Zibo Li
- Biomedical Research Imaging Center, Department of Radiology and UNC Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, United States
| | - Shuiyu Lu
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland 20892-1003, United States
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland 20892-1003, United States
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3
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Salerno S, Viviano M, Baglini E, Poggetti V, Giorgini D, Castagnoli J, Barresi E, Castellano S, Da Settimo F, Taliani S. TSPO Radioligands for Neuroinflammation: An Overview. Molecules 2024; 29:4212. [PMID: 39275061 PMCID: PMC11397380 DOI: 10.3390/molecules29174212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/30/2024] [Accepted: 09/03/2024] [Indexed: 09/16/2024] Open
Abstract
The translocator protein (TSPO) is predominately localized on the outer mitochondrial membrane in steroidogenic cells. In the brain, TSPO expression, low under normal conditions, results upregulated in response to glial cell activation, that occurs in neuroinflammation. As a consequence, TSPO has been extensively studied as a biomarker of such conditions by means of TSPO-targeted radiotracers. Although [11C]-PK11195, the prototypical TSPO radioligand, is still widely used for in vivo studies, it is endowed with severe limitations, mainly low sensitivity and poor amenability to quantification. Consequently, several efforts have been focused on the design of new radiotracers for the in vivo imaging of TSPO. The present review will provide an outlook on the latest advances in TSPO radioligands for neuroinflammation imaging. The final goal is to pave the way for (radio)chemists in the future design and development of novel effective and sensitive radiopharmaceuticals targeting TSPO.
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Affiliation(s)
- Silvia Salerno
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Monica Viviano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Emma Baglini
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Valeria Poggetti
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Doralice Giorgini
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Jacopo Castagnoli
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Elisabetta Barresi
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Federico Da Settimo
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
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4
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Hurtle BT, Jana S, Cai L, Pike VW. Ligand-Based Virtual Screening as a Path to New Chemotypes for Candidate PET Radioligands for Imaging Tauopathies. J Med Chem 2024; 67:14095-14109. [PMID: 39108178 DOI: 10.1021/acs.jmedchem.4c00934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Ligand-based virtual screening (LBVS) has rarely been tested as a method for discovering new structural scaffolds for PET radioligand development. This study used LBVS to discover potential chemotype leads for developing radioligands for PET imaging of tauopathies. ZINC12, a free database of over 12 million commercially available compounds, was searched to discover novel scaffolds based on similarities to four query compounds. Thirteen high-ranking hits were purchased and assayed for their ability to compete against three tritiated radioligands at their distinct binding sites in Alzheimer's disease brain tissue. Three hits were 2-substituted 6-methoxy naphthalenes. Synthetic elaboration of this new chemotype yielded three new ligands (25, 26, and 28) with high affinity for the [3H]6 (flortaucipur) neurofibrillary tangle binding site. Compound 28 showed remarkably high affinity (Ki, 7 nM) and other desirable properties for a candidate PET radioligand, including low topological polar surface area, moderate computed log D, and amenability for labeling with carbon-11. LBVS appears to be uniquely valuable for discovering new chemotypes for candidate PET radioligands.
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Affiliation(s)
- Bryan T Hurtle
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Susovan Jana
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Lisheng Cai
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
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5
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Xue L, Jie CVML, Desrayaud S, Auberson YP. Developing Low Molecular Weight PET and SPECT Imaging Agents. ChemMedChem 2024; 19:e202400094. [PMID: 38634545 DOI: 10.1002/cmdc.202400094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/17/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
Imaging agents for positron emission tomography (PET) and single-photon emission computerized tomography (SPECT) have shown their utility in many situations, answering clinical questions related to drug development and medical considerations. The discovery and development of imaging agents follow a well-understood process, with variations related to available starting points and to the envisaged imaging application. This article describes the general development path leading from the expression of an imaging need and project initiation to a clinically usable imaging agent. The definition of the project rationale, the design and optimization of early leads, and the assessment of the imaging potential of an imaging agent candidate are followed by preclinical and clinical development activities that differ from those required for therapeutic agents. These include radiolabeling with a positron emitter and first-in-human clinical studies, to rapidly evaluate the ability of a new imaging agent to address the questions it was designed to answer.
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Affiliation(s)
- Lian Xue
- Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade Parkville, Victoria 3052, Australia
| | - Caitlin V M L Jie
- ETH Zürich, Department of Chemistry and Applied Biosciences Center for Radiopharmaceutical Sciences, Vladimir-Prelog Weg 1-5/10, 8093, Zürich, Switzerland
| | - Sandrine Desrayaud
- Novartis Biomedical Research, In Vivo preclinical PK/ADME, Novartis campus, WSJ-352/6/73.01, 4056, Basel, Switzerland
| | - Yves P Auberson
- Novartis Biomedical Research, Global Discovery Chemistry, Novartis campus, WSJ-88.10.100, 4056, Basel, Switzerland
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6
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Fernandes EFA, Palner M, Raval NR, Jeppesen TE, Danková D, Bærentzen SL, Werner C, Eilts J, Maric HM, Doose S, Aripaka SS, Kaalund SS, Aznar S, Kjaer A, Schlosser A, Haugaard-Kedström LM, Knudsen GM, Herth MM, Stro Mgaard K. Development of Peptide-Based Probes for Molecular Imaging of the Postsynaptic Density in the Brain. J Med Chem 2024; 67:11975-11988. [PMID: 38981131 DOI: 10.1021/acs.jmedchem.4c00615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
The postsynaptic density (PSD) comprises numerous scaffolding proteins, receptors, and signaling molecules that coordinate synaptic transmission in the brain. Postsynaptic density protein 95 (PSD-95) is a master scaffold protein within the PSD and one of its most abundant proteins and therefore constitutes a very attractive biomarker of PSD function and its pathological changes. Here, we exploit a high-affinity inhibitor of PSD-95, AVLX-144, as a template for developing probes for molecular imaging of the PSD. AVLX-144-based probes were labeled with the radioisotopes fluorine-18 and tritium, as well as a fluorescent tag. Tracer binding showed saturable, displaceable, and uneven distribution in rat brain slices, proving effective in quantitative autoradiography and cell imaging studies. Notably, we observed diminished tracer binding in human post-mortem Parkinson's disease (PD) brain slices, suggesting postsynaptic impairment in PD. We thus offer a suite of translational probes for visualizing and understanding PSD-related pathologies.
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Affiliation(s)
- Eduardo F A Fernandes
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100, Denmark
| | - Mikael Palner
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, Copenhagen DK-2100, Denmark
| | - Nakul Ravi Raval
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, Copenhagen DK-2100, Denmark
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut 06520, United States
| | - Troels E Jeppesen
- Department of Clinical Physiology and Nuclear Medicine & Cluster for Molecular Imaging, Copenhagen University Hospital - Rigshospitalet & Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark
| | - Daniela Danková
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100, Denmark
| | - Simone L Bærentzen
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, Copenhagen DK-2100, Denmark
| | - Christian Werner
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University, Am Hubland, Würzburg D-97074, Germany
| | - Janna Eilts
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University, Am Hubland, Würzburg D-97074, Germany
| | - Hans M Maric
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100, Denmark
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Julius-Maximilians-University, Josef-Schneider-Str. 2, Würzburg 97080, Germany
| | - Sören Doose
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University, Am Hubland, Würzburg D-97074, Germany
| | - Sanjay Sagar Aripaka
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, Copenhagen DK-2100, Denmark
| | - Sanne Simone Kaalund
- Center for Neuroscience and Stereology, Bispebjerg University Hospital, Nielsine Nielsens Vej 6B, Copenhagen DK-2400, Denmark
| | - Susana Aznar
- Center for Neuroscience and Stereology, Bispebjerg University Hospital, Nielsine Nielsens Vej 6B, Copenhagen DK-2400, Denmark
- Center for Translational Research, Bispebjerg University Hospital, Nielsine Nielsens Vej 4B, Copenhagen DK-2400, Denmark
| | - Andreas Kjaer
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark
- Department of Clinical Physiology and Nuclear Medicine & Cluster for Molecular Imaging, Copenhagen University Hospital - Rigshospitalet & Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark
| | - Andreas Schlosser
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-University, Am Hubland, Würzburg D-97074, Germany
| | - Linda M Haugaard-Kedström
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100, Denmark
| | - Gitte M Knudsen
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, Copenhagen DK-2100, Denmark
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark
| | - Matthias M Herth
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100, Denmark
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, Copenhagen DK-2100, Denmark
- Department of Clinical Physiology and Nuclear Medicine & Cluster for Molecular Imaging, Copenhagen University Hospital - Rigshospitalet & Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark
| | - Kristian Stro Mgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100, Denmark
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7
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Wang J, Li Y, El Fakhri G. Advances and Insights in Positron Emission Tomography Tracers for Metabotropic Glutamate Receptor 4 Imaging. J Med Chem 2024; 67:10517-10529. [PMID: 38924702 PMCID: PMC11290609 DOI: 10.1021/acs.jmedchem.3c02431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
Positron emission tomography (PET) imaging employs positron-emitting radioisotopes to visualize biological processes in living subjects with high sensitivity and quantitative accuracy. As the most translational molecular imaging modality, PET can detect and image a wide range of radiotracers with minimal or no modification to parent drugs or targeting molecules. This Perspective provides a comprehensive analysis of developing PET radioligands using allosteric modulators for the metabotropic glutamate receptor subtype 4 (mGluR4) as a therapeutic target for neurological disorders. We focus on the selection of lead compounds from various chemotypes of mGluR4 positive allosteric modulators (PAMs) and discuss the challenges and systematic characterization required in developing brain-penetrant PET tracers specific for mGluR4. Through this analysis, we offer insights into the development and evaluation of PET ligands. Our review concludes that further research and development in this field hold great promise for discovering effective treatments for neurological disorders.
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Affiliation(s)
- Junfeng Wang
- Gordon Center for Medical Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Massachusetts, 02114, USA
| | - Yingbo Li
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Georges El Fakhri
- PET Center, School of Medicine, Yale University, Connecticut, 06520, USA
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8
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Zhao Q, Telu S, Jana S, Morse CL, Pike VW. Isotopologues of potassium 2,2,2-trifluoroethoxide for applications in positron emission tomography and beyond. Nat Commun 2024; 15:5798. [PMID: 38987549 PMCID: PMC11237122 DOI: 10.1038/s41467-024-49975-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 06/26/2024] [Indexed: 07/12/2024] Open
Abstract
The 2,2,2-trifluoroethoxy group increasingly features in drugs and potential tracers for biomedical imaging with positron emission tomography (PET). Herein, we describe a rapid and transition metal-free conversion of fluoroform with paraformaldehyde into highly reactive potassium 2,2,2-trifluoroethoxide (CF3CH2OK) and demonstrate robust applications of this synthon in one-pot, two-stage 2,2,2-trifluoroethoxylations of both aromatic and aliphatic precursors. Moreover, we show that these transformations translate easily to fluoroform that has been labeled with either carbon-11 (t1/2 = 20.4 min) or fluorine-18 (t1/2 = 109.8 min), so allowing the appendage of complex molecules with a no-carrier-added 11C- or 18F- 2,2,2-trifluoroethoxy group. This provides scope to create candidate PET tracers with radioactive and metabolically stable 2,2,2-trifluoroethoxy moieties. We also exemplify syntheses of isotopologues of potassium 2,2,2-trifluoroethoxide and show their utility for stable isotopic labeling which can be of further benefit for drug discovery and development.
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Affiliation(s)
- Qunchao Zhao
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD, 20892-1003, USA.
| | - Susovan Jana
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD, 20892-1003, USA.
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9
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Siva NK, Bauer C, Glover C, Stolin A, Chandi S, Melnick H, Marano G, Parker B, Mandich M, Lewis JW, Qi J, Gao S, Nott K, Majewski S, Brefczynski-Lewis JA. Real-time motion-enabling positron emission tomography of the brain of upright ambulatory humans. COMMUNICATIONS MEDICINE 2024; 4:117. [PMID: 38872007 PMCID: PMC11176317 DOI: 10.1038/s43856-024-00547-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/05/2024] [Indexed: 06/15/2024] Open
Abstract
BACKGROUND Mobile upright PET devices have the potential to enable previously impossible neuroimaging studies. Currently available options are imagers with deep brain coverage that severely limit head/body movements or imagers with upright/motion enabling properties that are limited to only covering the brain surface. METHODS In this study, we test the feasibility of an upright, motion-compatible brain imager, our Ambulatory Motion-enabling Positron Emission Tomography (AMPET) helmet prototype, for use as a neuroscience tool by replicating a variant of a published PET/fMRI study of the neurocorrelates of human walking. We validate our AMPET prototype by conducting a walking movement paradigm to determine motion tolerance and assess for appropriate task related activity in motor-related brain regions. Human participants (n = 11 patients) performed a walking-in-place task with simultaneous AMPET imaging, receiving a bolus delivery of F18-Fluorodeoxyglucose. RESULTS Here we validate three pre-determined measure criteria, including brain alignment motion artifact of less than <2 mm and functional neuroimaging outcomes consistent with existing walking movement literature. CONCLUSIONS The study extends the potential and utility for use of mobile, upright, and motion-tolerant neuroimaging devices in real-world, ecologically-valid paradigms. Our approach accounts for the real-world logistics of an actual human participant study and can be used to inform experimental physicists, engineers and imaging instrumentation developers undertaking similar future studies. The technical advances described herein help set new priorities for facilitating future neuroimaging devices and research of the human brain in health and disease.
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Affiliation(s)
- Nanda K Siva
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | | | - Colson Glover
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Alexander Stolin
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Sonia Chandi
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Helen Melnick
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Gary Marano
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Benjamin Parker
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - MaryBeth Mandich
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - James W Lewis
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Jinyi Qi
- Department of Biomedical Engineering, University of California, Davis, Davis, CA, USA
| | - Si Gao
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Kaylee Nott
- Department of Neuroscience, West Virginia University, P.O. Box 9303, Morgantown, WV, USA
| | - Stan Majewski
- Department of Biomedical Engineering, University of California, Davis, Davis, CA, USA
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10
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Bonanno F, Saw RS, Bleher D, Papadopoulos I, Bowden GD, Bjerregaard-Andersen K, Windhorst AD, Pichler BJ, Herfert K, Maurer A. Advancing Parkinson's Disease Diagnostics: The Potential of Arylpyrazolethiazole Derivatives for Imaging α-Synuclein Aggregates. ACS OMEGA 2024; 9:24774-24788. [PMID: 38882134 PMCID: PMC11170759 DOI: 10.1021/acsomega.4c01301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/24/2024] [Accepted: 05/15/2024] [Indexed: 06/18/2024]
Abstract
The development of positron emission tomography (PET) tracers capable of detecting α-synuclein (α-syn) aggregates in vivo would represent a breakthrough for advancing the understanding and enabling the early diagnosis of Parkinson's disease and related disorders. It also holds the potential to assess the efficacy of therapeutic interventions. However, this remains challenging due to different structures of α-syn aggregates, the need for selectivity over other structurally similar amyloid proteins, like amyloid-β (Aβ), which frequently coexist with α-syn pathology, and the low abundance of the target in the brain that requires the development of a high-affinity ligand. To develop a successful PET tracer for the central nervous system (CNS), stringent criteria in terms of polarity and molecular size must also be considered, as the tracer must penetrate the blood-brain barrier and have low nonspecific binding to brain tissue. Here, we report a series of arylpyrazolethiazole (APT) derivatives, rationally designed from a structure-activity relationship study centered on existing ligands for α-syn fibrils, with a particular focus on the selectivity toward α-syn fibrils and control of physicochemical properties suitable for a CNS PET tracer. In vitro competition binding assays performed against [3H]MODAG-001 using recombinant α-syn and Aβ1-42 fibrils revealed APT-13 with an inhibition constant of 27.8 ± 9.7 nM and a selectivity of more than 3.3 fold over Aβ. Radiolabeled [11C]APT-13 demonstrated excellent brain penetration in healthy mice with a peak standardized uptake value of 1.94 ± 0.29 and fast washout from the brain (t 1/2 = 9 ± 1 min). This study highlights the potential of APT-13 as a lead compound for developing PET tracers to detect α-syn aggregates in vivo.
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Affiliation(s)
- Federica Bonanno
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
| | - Ran Sing Saw
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
| | - Daniel Bleher
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
| | - Ioannis Papadopoulos
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
| | - Gregory D Bowden
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, Röntgenweg 11, Tübingen 72076, Germany
| | | | - Albert D Windhorst
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1085c, 1081 HV Amsterdam, The Netherlands
| | - Bernd J Pichler
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, Röntgenweg 11, Tübingen 72076, Germany
| | - Kristina Herfert
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
| | - Andreas Maurer
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, Tübingen 72076, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, Röntgenweg 11, Tübingen 72076, Germany
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11
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Jiang M, Tang S, Jenkins MD, Lee AC, Kenou B, Knoer C, Montero Santamaria J, Wu S, Liow JS, Zoghbi SS, Zanotti-Fregonara P, Innis RB, Telu S, Pike VW. Robust Quantification of Phosphodiesterase-4D in Monkey Brain with PET and 11C-Labeled Radioligands That Avoid Radiometabolite Contamination. J Nucl Med 2024; 65:788-793. [PMID: 38423785 PMCID: PMC11064827 DOI: 10.2967/jnumed.123.266750] [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] [Received: 09/27/2023] [Revised: 01/05/2024] [Indexed: 03/02/2024] Open
Abstract
Phosphodiesterase-4D (PDE4D) has emerged as a significant target for treating neuropsychiatric disorders, but no PET radioligand currently exists for robustly quantifying human brain PDE4D to assist biomedical research and drug discovery. A prior candidate PDE4D PET radioligand, namely [11C]T1650, failed in humans because of poor time stability of brain PDE4D-specific signal (indexed by total volume of distribution), likely due to radiometabolites accumulating in brain. Its nitro group was considered to be a source of the brain radiometabolites. Methods: We selected 5 high-affinity and selective PDE4D inhibitors, absent of a nitro group, from our prior structure-activity relationship study for evaluation as PET radioligands. Results: All 5 radioligands were labeled with 11C (half-time, 20.4 min) in useful yields and with high molar activity. All displayed sizable PDE4D-specific signals in rhesus monkey brain. Notably, [11C]JMJ-81 and [11C]JMJ-129 exhibited excellent time stability of signal (total volume of distribution). Furthermore, as an example, [11C]JMJ-81 was found to be free of radiometabolites in ex vivo monkey brain, affirming that this radioligand can provide robust quantification of brain PDE4D with PET. Conclusion: Given their high similarity in structures and metabolic profiles, both [11C]JMJ-81 and [11C]JMJ-129 warrant further evaluation in human subjects. [11C]JMJ-129 shows a higher PDE4D specific-to-nonspecific binding ratio and will be the first to be evaluated.
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Affiliation(s)
- Meijuan Jiang
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Shiyu Tang
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Madeline D Jenkins
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Adrian C Lee
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Bruny Kenou
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Carson Knoer
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Jose Montero Santamaria
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Shawn Wu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Paolo Zanotti-Fregonara
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
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12
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Jiang H, Roy P, Guo Y, Muzik O, Woodcock EA. Automated radiosynthesis of [ 11C]CPPC for in-human PET imaging applications. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2024; 14:144-148. [PMID: 38737641 PMCID: PMC11087290 DOI: 10.62347/mxkz6739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 04/08/2024] [Indexed: 05/14/2024]
Abstract
The macrophage colony-stimulating factor 1 receptor (CSF1R) is almost exclusively expressed in microglia, representing a biomarker target for imaging of microglia availability. [11C]CPPC has specific binding affinity to CSF1R and suitable kinetic properties for in vivo PET imaging of microglia. However, previous studies reported a low radiochemical yield, motivating additional research to optimize [11C]CPPC radiochemistry. In this work, we report an automated radiosynthesis of [11C]CPPC on a Synthra MeIPlus module with improved radiochemical yield. The final [11C]CPPC product was obtained with excellent chemical/radiochemical purities and molecular activity, facilitating high-quality in-human PET imaging applications.
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Affiliation(s)
- Huailei Jiang
- Cyclotron and Radiochemistry Core, Karmanos Cancer InstituteDetroit, MI, USA
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Oncology, Wayne State UniversityDetroit, MI, USA
| | - Pritam Roy
- Cyclotron and Radiochemistry Core, Karmanos Cancer InstituteDetroit, MI, USA
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Oncology, Wayne State UniversityDetroit, MI, USA
| | - Yan Guo
- Cyclotron and Radiochemistry Core, Karmanos Cancer InstituteDetroit, MI, USA
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Oncology, Wayne State UniversityDetroit, MI, USA
| | - Otto Muzik
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Pediatrics and Neurology, Wayne State UniversityDetroit, MI, USA
| | - Eric A Woodcock
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of MedicineDetroit, MI, USA
- Department of Pharmacology, Wayne State University School of MedicineDetroit, MI, USA
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13
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Nerella SG, Telu S, Liow JS, Jenkins MD, Zoghbi SS, Gomez JL, Michaelides M, Eldridge MAG, Richmond BJ, Innis RB, Pike VW. Synthesis and preclinical evaluation of [ 11C]uPSEM792 for PSAM 4-GlyR based chemogenetics. Sci Rep 2024; 14:1886. [PMID: 38253691 PMCID: PMC10803328 DOI: 10.1038/s41598-024-51307-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 01/01/2024] [Indexed: 01/24/2024] Open
Abstract
Chemogenetic tools are designed to control neuronal signaling. These tools have the potential to contribute to the understanding of neuropsychiatric disorders and to the development of new treatments. One such chemogenetic technology comprises modified Pharmacologically Selective Actuator Modules (PSAMs) paired with Pharmacologically Selective Effector Molecules (PSEMs). PSAMs are receptors with ligand-binding domains that have been modified to interact only with a specific small-molecule agonist, designated a PSEM. PSAM4 is a triple mutant PSAM derived from the α7 nicotinic receptor (α7L131G,Q139L,Y217F). Although having no constitutive activity as a ligand-gated ion channel, PSAM4 has been coupled to the serotonin 5-HT3 receptor (5-HT3R) and to the glycine receptor (GlyR). Treatment with the partner PSEM to activate PSAM4-5-HT3 or PSAM4-GlyR, causes neuronal activation or silencing, respectively. A suitably designed radioligand may enable selective visualization of the expression and location of PSAMs with positron emission tomography (PET). Here, we evaluated uPSEM792, an ultrapotent PSEM for PSAM4-GlyR, as a possible lead for PET radioligand development. We labeled uPSEM792 with the positron-emitter, carbon-11 (t1/2 = 20.4 min), in high radiochemical yield by treating a protected precursor with [11C]iodomethane followed by base deprotection. PET experiments with [11C]uPSEM792 in rodents and in a monkey transduced with PSAM4-GlyR showed low peak radioactivity uptake in brain. This low uptake was probably due to high polarity of the radioligand, as evidenced by physicochemical measurements, and to the vulnerability of the radioligand to efflux transport at the blood-brain barrier. These findings can inform the design of a more effective PSAM4 based PET radioligand, based on the uPSEM792 chemotype.
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Affiliation(s)
- Sridhar Goud Nerella
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Madeline D Jenkins
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Juan L Gomez
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Michael Michaelides
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Mark A G Eldridge
- Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Barry J Richmond
- Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.
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14
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Pijeira MSO, Nunes PSG, Chaviano SL, Diaz AMA, DaSilva JN, Ricci-Junior E, Alencar LMR, Chen X, Santos-Oliveira R. Medicinal (Radio) Chemistry: Building Radiopharmaceuticals for the Future. Curr Med Chem 2024; 31:5481-5534. [PMID: 37594105 DOI: 10.2174/0929867331666230818092634] [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] [Received: 03/10/2023] [Revised: 05/30/2023] [Accepted: 07/13/2023] [Indexed: 08/19/2023]
Abstract
Radiopharmaceuticals are increasingly playing a leading role in diagnosing, monitoring, and treating disease. In comparison with conventional pharmaceuticals, the development of radiopharmaceuticals does follow the principles of medicinal chemistry in the context of imaging-altered physiological processes. The design of a novel radiopharmaceutical has several steps similar to conventional drug discovery and some particularity. In the present work, we revisited the insights of medicinal chemistry in the current radiopharmaceutical development giving examples in oncology, neurology, and cardiology. In this regard, we overviewed the literature on radiopharmaceutical development to study overexpressed targets such as prostate-specific membrane antigen and fibroblast activation protein in cancer; β-amyloid plaques and tau protein in brain disorders; and angiotensin II type 1 receptor in cardiac disease. The work addresses concepts in the field of radiopharmacy with a special focus on the potential use of radiopharmaceuticals for nuclear imaging and theranostics.
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Affiliation(s)
- Martha Sahylí Ortega Pijeira
- Laboratory of Nanoradiopharmaceuticals and Synthesis of Novel Radiopharmaceuticals, Brazilian Nuclear Energy Commission, Nuclear Engineering Institute, Rio de Janeiro 21941906, Brazil
| | - Paulo Sérgio Gonçalves Nunes
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas SP13083-970, Brazil
| | - Samila Leon Chaviano
- Laboratoire de Biomatériaux pour l'Imagerie Médicale, Axe Médicine Régénératrice, Centre de Recherche du Centre Hospitalier Universitaire de Québec - Université Laval, Québec, QC, Canada
| | - Aida M Abreu Diaz
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
- Institute de Génie Biomédical, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
| | - Jean N DaSilva
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
- Institute de Génie Biomédical, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
| | - Eduardo Ricci-Junior
- Laboratório de Desenvolvimento Galênico, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil
| | - Luciana Magalhães Rebelo Alencar
- Laboratory of Biophysics and Nanosystems, Federal University of Maranhão, Av. dos Portugueses, 1966, Vila Bacanga, São Luís MA65080-805, Brazil
| | - Xiaoyuan Chen
- Departments of Diagnostic Radiology, Chemical and Biomolecular Engineering, and Biomedical Engineering, Yong Loo Lin School of Medicine and Faculty of Engineering, National University of Singapore 117597, Singapore
- Clinical Imaging Research Centre, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 117599, Singapore
- Nanomedicine Translational Research Program, NUS Center for Nanomedicine, Yong Loo Lin School of Medicine, National University of Singapore 117597, Singapore
| | - Ralph Santos-Oliveira
- Laboratory of Nanoradiopharmaceuticals and Synthesis of Novel Radiopharmaceuticals, Brazilian Nuclear Energy Commission, Nuclear Engineering Institute, Rio de Janeiro 21941906, Brazil
- Laboratory of Radiopharmacy and Nanoradiopharmaceuticals, Rio de Janeiro State University, Rio de Janeiro 23070200, Brazil
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15
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Li Y, Wang J. Site-specifically radiolabeled nanobodies for imaging blood-brain barrier penetration and targeting in the brain. J Labelled Comp Radiopharm 2023; 66:444-451. [PMID: 37873934 PMCID: PMC10842159 DOI: 10.1002/jlcr.4069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/22/2023] [Accepted: 10/03/2023] [Indexed: 10/25/2023]
Abstract
Nanobodies (Nbs) hold significant potential in molecular imaging due to their unique characteristics. However, there are challenges to overcome when it comes to brain imaging. To address these obstacles, collaborative efforts and interdisciplinary research are needed. This article aims to raise awareness and encourage collaboration among researchers from various fields to find solutions for effective brain imaging using Nbs. By fostering cooperation and knowledge sharing, we can make progress in overcoming the existing limitations and pave the way for improved molecular imaging techniques in the future.
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Affiliation(s)
- Yingbo Li
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Junfeng Wang
- Gordon Center for Medical Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
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16
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Altomonte S, Pike VW. Candidate Tracers for Imaging Colony-Stimulating Factor 1 Receptor in Neuroinflammation with Positron Emission Tomography: Issues and Progress. ACS Pharmacol Transl Sci 2023; 6:1632-1650. [PMID: 37974622 PMCID: PMC10644394 DOI: 10.1021/acsptsci.3c00213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Indexed: 11/19/2023]
Abstract
The tyrosine kinase, colony-stimulating factor 1 receptor (CSF1R), has attracted attention as a potential biomarker of neuroinflammation for imaging studies with positron emission tomography (PET), especially because of its location on microglia and its role in microglia proliferation. The development of an effective radiotracer for specifically imaging and quantifying brain CSF1R is highly challenging. Here we review the progress that has been made on PET tracer development and discuss issues that have arisen and which remain to be addressed and resolved.
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Affiliation(s)
- Stefano Altomonte
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes
of Health, Building 10,
B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes
of Health, Building 10,
B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
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17
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Arjmand S, Bender D, Jakobsen S, Wegener G, Landau AM. Peering into the Brain's Estrogen Receptors: PET Tracers for Visualization of Nuclear and Extranuclear Estrogen Receptors in Brain Disorders. Biomolecules 2023; 13:1405. [PMID: 37759805 PMCID: PMC10526964 DOI: 10.3390/biom13091405] [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] [Received: 08/10/2023] [Revised: 09/12/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
Estrogen receptors (ERs) play a multitude of roles in brain function and are implicated in various brain disorders. The use of positron emission tomography (PET) tracers for the visualization of ERs' intricate landscape has shown promise in oncology but remains limited in the context of brain disorders. Despite recent progress in the identification and development of more selective ligands for various ERs subtypes, further optimization is necessary to enable the reliable and efficient imaging of these receptors. In this perspective, we briefly touch upon the significance of estrogen signaling in the brain and raise the setbacks associated with the development of PET tracers for identification of specific ERs subtypes in the brain. We then propose avenues for developing efficient PET tracers to non-invasively study the dynamics of ERs in the brain, as well as neuropsychiatric diseases associated with their malfunction in a longitudinal manner. This perspective puts several potential candidates on the table and highlights the unmet needs and areas requiring further research to unlock the full potential of PET tracers for ERs imaging, ultimately aiding in deepening our understanding of ERs and forging new avenues for potential therapeutic strategies.
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Affiliation(s)
- Shokouh Arjmand
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark;
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, 8200 Aarhus, Denmark; (D.B.); (S.J.)
| | - Dirk Bender
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, 8200 Aarhus, Denmark; (D.B.); (S.J.)
| | - Steen Jakobsen
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, 8200 Aarhus, Denmark; (D.B.); (S.J.)
| | - Gregers Wegener
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark;
| | - Anne M. Landau
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark;
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, 8200 Aarhus, Denmark; (D.B.); (S.J.)
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18
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Turkman N, Xu S, Huang CH, Eyermann C, Salino J, Khan P. High-Contrast PET Imaging with [ 18F]NT160, a Class-IIa Histone Deacetylase Probe for In Vivo Imaging of Epigenetic Machinery in the Central Nervous System. J Med Chem 2023; 66:5611-5621. [PMID: 37068265 PMCID: PMC10150721 DOI: 10.1021/acs.jmedchem.2c02064] [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: 12/16/2022] [Indexed: 04/19/2023]
Abstract
We utilized positron emission tomography (PET) imaging in vivo to map the spatiotemporal biodistribution/expression of class-IIa histone deacetylases (class-IIa HDACs) in the central nervous system (CNS). Herein we report an improved radiosynthesis of [18F]NT160 using 4-hydroxy-TEMPO which led to a significant improvement in radiochemical yield and molar activity. PET imaging with [18F]NT160, a highly potent class-IIa HDAC inhibitor, led to high-quality and high-contrast images of the brain. [18F]NT160 displayed excellent pharmacokinetic and imaging characteristics: brain uptake is high in gray matter regions, tissue kinetics are appropriate for a 18F-tracer, and specific binding for class-IIa HDACs is demonstrated by self-blockade. Higher uptake with [18F]NT160 was observed in the hippocampus, thalamus, and cortex while the uptake in the cerebellum was relatively low. Overall, our current studies with [18F]NT160 will likely facilitate the development and clinical translation of PET tracers for imaging of class-IIa HDACs biodistribution/expression in cancer and the CNS.
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Affiliation(s)
- Nashaat Turkman
- Stony
Brook Cancer Center, Stony Brook, Long Island, New York 11794, United States
- Department
of Radiology, School of Medicine, Stony
Brook University, Long Island, New York 11794, United States
- Department
of Biomedical Engineering, Stony Brook University, Long Island, New York 11794, United States
| | - Sulan Xu
- Stony
Brook Cancer Center, Stony Brook, Long Island, New York 11794, United States
- Department
of Radiology, School of Medicine, Stony
Brook University, Long Island, New York 11794, United States
| | - Chun-Han Huang
- Stony
Brook Cancer Center, Stony Brook, Long Island, New York 11794, United States
- Department
of Radiology, School of Medicine, Stony
Brook University, Long Island, New York 11794, United States
- Department
of Biomedical Engineering, Stony Brook University, Long Island, New York 11794, United States
| | - Christopher Eyermann
- Department
of Radiology, School of Medicine, Stony
Brook University, Long Island, New York 11794, United States
- Department
of Surgery, School of Medicine, Stony Brook
University, Long Island, New York 11794, United States
| | - Julia Salino
- Stony
Brook Cancer Center, Stony Brook, Long Island, New York 11794, United States
- Department
of Radiology, School of Medicine, Stony
Brook University, Long Island, New York 11794, United States
| | - Palwasha Khan
- Stony
Brook Cancer Center, Stony Brook, Long Island, New York 11794, United States
- Department
of Radiology, School of Medicine, Stony
Brook University, Long Island, New York 11794, United States
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19
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Altomonte S, Yan X, Morse CL, Liow JS, Jenkins MD, Montero Santamaria JA, Zoghbi SS, Innis RB, Pike VW. Discovery of a High-Affinity Fluoromethyl Analog of [ 11C]5-Cyano- N-(4-(4-methylpiperazin-1-yl)-2-(piperidin-1-yl)phenyl)furan-2-carboxamide ([ 11C]CPPC) and Their Comparison in Mouse and Monkey as Colony-Stimulating Factor 1 Receptor Positron Emission Tomography Radioligands. ACS Pharmacol Transl Sci 2023; 6:614-632. [PMID: 37082755 PMCID: PMC10111626 DOI: 10.1021/acsptsci.3c00003] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Indexed: 03/12/2023]
Abstract
[11C]CPPC has been advocated as a radioligand for colony-stimulating factor 1 receptor (CSF1R) with the potential for imaging neuroinflammation in human subjects with positron emission tomography (PET). This study sought to prepare fluoro analogs of CPPC with higher affinity to provide the potential for labeling with longer-lived fluorine-18 (t 1/2 = 109.8 min) and for delivery of higher CSF1R-specific PET signal in vivo. Seven fluorine-containing analogs of CPPC were prepared and four were found to have high inhibitory potency (IC50 in low to sub-nM range) and selectivity at CSF1R comparable with CPPC itself. One of these, a 4-fluoromethyl analog (Psa374), was investigated more deeply by labeling with carbon-11 (t 1/2 = 20.4 min) for PET studies in mouse and monkey. [11C]Psa374 showed high peak uptake in monkey brain but not in mouse brain. Pharmacological challenges revealed no CSF1R-specific binding in either species at baseline. [11C]CPPC also failed to show specific binding at baseline. Moreover, both [11C]Psa374 and [11C]CPPC showed brain efflux transporter substrate behavior in both species in vivo, although Psa374 did not show liability toward human efflux transporters in vitro. Further development of [11C]Psa374 in non-human primate models of neuroinflammation with demonstration of CSF1R-specific binding would be required to warrant the fluorine-18 labeling of Psa374 with a view to possible application in human subjects.
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Affiliation(s)
- Stefano Altomonte
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Xuefeng Yan
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Cheryl L. Morse
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Jeih-San Liow
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Madeline D. Jenkins
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Jose A. Montero Santamaria
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Sami S. Zoghbi
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Robert B. Innis
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Victor W. Pike
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
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20
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Qiu L, Jiang H, Zhou C, Wang J, Yu Y, Zhao H, Huang T, Gropler R, Perlmutter JS, Benzinger TLS, Tu Z. Discovery of a Promising Fluorine-18 Positron Emission Tomography Radiotracer for Imaging Sphingosine-1-Phosphate Receptor 1 in the Brain. J Med Chem 2023; 66:4671-4688. [PMID: 36926861 PMCID: PMC11037415 DOI: 10.1021/acs.jmedchem.2c01752] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Sphingosine-1-phosphate receptor 1 (S1PR1) is recognized as a novel therapeutic and diagnostic target in neurological disorders. We recently transferred the S1PR1 radioligand [11C]CS1P1 into clinical investigation for multiple sclerosis. Herein, we reported the design, synthesis and evaluation of novel F-18 S1PR1 radioligands. We combined the structural advantages of our two lead S1PR1 radioligands and synthesized 14 new S1PR1 compounds, then performed F-18 radiochemistry on the most promising compounds. Compound 6h is potent (IC50 = 8.7 nM) and selective for S1PR1. [18F]6h exhibited a high uptake in macaque brain (SUV > 3.0) and favorable brain washout pharmacokinetics in positron emission tomography (PET) study. PET blocking and displacement studies confirmed the specificity of [18F]6h in vivo. Radiometabolite analysis confirmed no radiometabolite of [18F]6h entered into the brain to confound the PET measurement. In summary, [18F]6h is a promising radioligand to image S1PR1 and worth translational clinical investigation for humans with brain disorders.
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Affiliation(s)
- Lin Qiu
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Hao Jiang
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Charles Zhou
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Jinzhi Wang
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Yanbo Yu
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Haiyang Zhao
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Tianyu Huang
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Robert Gropler
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Joel S Perlmutter
- Department of Neurology, Radiology, Neuroscience, Physical Therapy and Occupational Therapy, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Tammie L S Benzinger
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
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21
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Cai L, Liow JS, Morse CL, Telu S, Davies R, Manly LS, Zoghbi SS, Chin FT, Innis RB, Pike VW. Candidate 3-benzazepine-1-ol type GluN2B receptor radioligands ( 11C-NR2B-Me enantiomers) have high binding in cerebellum but not to σ1 receptors. EJNMMI Res 2023; 13:28. [PMID: 37017827 PMCID: PMC10076467 DOI: 10.1186/s13550-023-00975-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 03/12/2023] [Indexed: 04/06/2023] Open
Abstract
INTRODUCTION We recently reported 11C-NR2B-SMe ([S-methyl-11C](R,S)-7-thiomethoxy-3-(4-(4-methyl-phenyl)butyl)-2,3,4,5-tetrahydro-1H-benzo[d]azepin-1-ol) and its enantiomers as candidate radioligands for imaging the GluN2B subunit within rat N-methyl-D-aspartate receptors. However, these radioligands gave unexpectedly high and displaceable binding in rat cerebellum, possibly due to cross-reactivity with sigma-1 (σ1) receptors. This study investigated 11C-labeled enantiomers of a close analogue (7-methoxy-3-(4-(p-tolyl)butyl)-2,3,4,5-tetrahydro-1H-benzo[d]azepin-1-ol; NR2B-Me) of 11C-NR2B-SMe as new candidate GluN2B radioligands. PET was used to evaluate these radioligands in rats and to assess potential cross-reactivity to σ1 receptors. METHODS NR2B-Me was assayed for binding affinity and selectivity to GluN2B in vitro. 11C-NR2B-Me and its enantiomers were prepared by Pd-mediated treatment of boronic ester precursors with 11C-iodomethane. Brain PET scans were conducted after radioligand intravenous injection into rats. Various ligands for GluN2B receptors or σ1 receptors were administered at set doses in pre-blocking or displacement experiments to assess their impact on imaging data. 18F-FTC146 and enantiomers of 11C-NR2B-SMe were used for comparison. Radiometabolites from brain and plasma were measured ex vivo and in vitro. RESULTS NR2B-Me enantiomers showed high GluN2B affinity and selectivity in vitro. 11C-NR2B-Me enantiomers gave high early whole rat brain uptake of radioactivity, including high uptake in cerebellum, followed by slower decline. Radioactivity in brain at 30 min ex vivo was virtually all unchanged radioligand. Only less lipophilic radiometabolites appeared in plasma. When 11C-(R)-NR2B-Me was used, three high-affinity GluN2B ligands-NR2B-SMe, Ro25-6981, and CO101,244-showed increasing pre-block of whole brain radioactivity retention with increasing dose. Two σ1 receptor antagonists, FTC146 and BD1407, were ineffective pre-blocking agents. Together, these results strongly resemble those obtained with 11C-NR2B-SMe enantiomers, except that 11C-NR2B-Me enantiomers showed faster reversibility of binding. When 18F-FTC146 was used as a radioligand, FTC146 and BD1407 showed strong pre-blocking effects whereas GluN2B ligands showed only weak blocking effects. CONCLUSION 11C-NR2B-Me enantiomers showed specific binding to GluN2B receptors in rat brain in vivo. High unexpected specific binding in cerebellum was not due to σ1 receptors. Additional investigation is needed to identify the source of the high specific binding.
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Affiliation(s)
- Lisheng Cai
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA.
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Riley Davies
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Lester S Manly
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Frederick T Chin
- Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, 1201 Welch Road, Rm. PS049, Stanford, CA, 94305-584, USA
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Dr, Bldg 10, Room B3 C346, Bethesda, MD, 20892, USA
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22
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Yu Y, Jiang H, Liang Q, Qiu L, Huang T, Hu H, Bolshakov VY, Perlmutter JS, Tu Z. Radiosynthesis and Evaluation of a C-11 Radiotracer for Transient Receptor Potential Canonical 5 in the Brain. Mol Imaging Biol 2023; 25:334-342. [PMID: 35951211 PMCID: PMC9918595 DOI: 10.1007/s11307-022-01760-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 10/15/2022]
Abstract
PURPOSE TRPC5 belongs to the mammalian superfamily of transient receptor potential (TRP) Ca2+-permeable cationic channels and it has been implicated in various CNS disorders. As part of our ongoing interest in the development of a PET radiotracer for imaging TRPC5, herein, we explored the radiosynthesis, and in vitro and in vivo evaluation of a new C-11 radiotracer [11C]HC070 in rodents and nonhuman primates. PROCEDURES [11C]HC070 was radiolabeled utilizing the corresponding precursor and [11C]CH3I via N-methylation protocol. Ex vivo biodistribution study of [11C]HC070 was performed in Sprague-Dawley rats. In vitro autoradiography study was conducted for the rat brain sections to characterize the radiotracer distribution in the brain regionals. MicroPET brain imaging studies of [11C]HC070 were done for 129S1/SvImJ wild-type mice and 129S1/SvImJ TRPC5 knockout mice for 0-60-min dynamic data acquisition after intravenous administration of the radiotracer. Dynamic PET scans (0-120 min) for the brain of cynomolgus male macaques were performed after the radiotracer injection. RESULTS [11C]HC070 was efficiently prepared with good radiochemical yield (45 ± 5%, n = 15), high chemical and radiochemical purity (> 99%), and high molar activity (320.6 ± 7.4 GBq/μmol, 8.6 ± 0.2 Ci/μmol) at the end of bombardment (EOB). Radiotracer [11C]HC070 has good solubility in the aqueous dose solution. The ex vivo biodistribution study showed that [11C]HC070 had a quick rat brain clearance. Autoradiography demonstrated that [11C]HC070 specifically binds to TRPC5-enriched regions in rat brain. MicroPET study showed the peak brain uptake (SUV value) was 0.63 in 129S1/SvImJ TRPC5 knockout mice compared to 1.13 in 129S1/SvImJ wild-type mice. PET study showed that [11C]HC070 has good brain uptake with maximum SUV of ~ 2.2 in the macaque brain, followed by rapid clearance. CONCLUSIONS Our data showed that [11C]HC070 is a TRPC5-specific radiotracer with high brain uptake and good brain washout pharmacokinetics in both rodents and nonhuman primates. The radiotracer is worth further investigating of its suitability to be a PET radiotracer for imaging TRPC5 in animals and human subjects in vivo.
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Affiliation(s)
- Yanbo Yu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hao Jiang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Qianwa Liang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Lin Qiu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Tianyu Huang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hongzhen Hu
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Vadim Y Bolshakov
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Joel S Perlmutter
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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23
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Neumaier F, Zlatopolskiy BD, Neumaier B. Mutated Isocitrate Dehydrogenase (mIDH) as Target for PET Imaging in Gliomas. Molecules 2023; 28:molecules28072890. [PMID: 37049661 PMCID: PMC10096429 DOI: 10.3390/molecules28072890] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/21/2023] [Accepted: 03/21/2023] [Indexed: 04/14/2023] Open
Abstract
Gliomas are the most common primary brain tumors in adults. A diffuse infiltrative growth pattern and high resistance to therapy make them largely incurable, but there are significant differences in the prognosis of patients with different subtypes of glioma. Mutations in isocitrate dehydrogenase (IDH) have been recognized as an important biomarker for glioma classification and a potential therapeutic target. However, current clinical methods for detecting mutated IDH (mIDH) require invasive tissue sampling and cannot be used for follow-up examinations or longitudinal studies. PET imaging could be a promising approach for non-invasive assessment of the IDH status in gliomas, owing to the availability of various mIDH-selective inhibitors as potential leads for the development of PET tracers. In the present review, we summarize the rationale for the development of mIDH-selective PET probes, describe their potential applications beyond the assessment of the IDH status and highlight potential challenges that may complicate tracer development. In addition, we compile the major chemical classes of mIDH-selective inhibitors that have been described to date and briefly consider possible strategies for radiolabeling of the most promising candidates. Where available, we also summarize previous studies with radiolabeled analogs of mIDH inhibitors and assess their suitability for PET imaging in gliomas.
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Affiliation(s)
- Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Boris D Zlatopolskiy
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
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24
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Raval NR, Wetherill RR, Wiers CE, Dubroff JG, Hillmer AT. Positron Emission Tomography of Neuroimmune Responses in Humans: Insights and Intricacies. Semin Nucl Med 2023; 53:213-229. [PMID: 36270830 PMCID: PMC11261531 DOI: 10.1053/j.semnuclmed.2022.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 08/30/2022] [Indexed: 11/06/2022]
Abstract
The brain's immune system plays a critical role in responding to immune challenges and maintaining homeostasis. However, dysregulated neuroimmune function contributes to neurodegenerative disease and neuropsychiatric conditions. In vivo positron emission tomography (PET) imaging of the neuroimmune system has facilitated a greater understanding of its physiology and the pathology of some neuropsychiatric conditions. This review presents an in-depth look at PET findings from human neuroimmune function studies, highlighting their importance in current neuropsychiatric research. Although the majority of human PET studies feature radiotracers targeting the translocator protein 18 kDa (TSPO), this review also considers studies with other neuroimmune targets, including monoamine oxidase B, cyclooxygenase-1 and cyclooxygenase-2, nitric oxide synthase, and the purinergic P2X7 receptor. Promising new targets, such as colony-stimulating factor 1, Sphingosine-1-phosphate receptor 1, and the purinergic P2Y12 receptor, are also discussed. The significance of validating neuroimmune targets and understanding their function and expression is emphasized in this review to better identify and interpret PET results.
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Affiliation(s)
- Nakul R Raval
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; Yale PET Center, Yale University, New Haven, CT
| | - Reagan R Wetherill
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Corinde E Wiers
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Jacob G Dubroff
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Ansel T Hillmer
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; Yale PET Center, Yale University, New Haven, CT; Department of Psychiatry, Yale University, New Haven, CT.
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25
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Singh P, Singh D, Srivastava P, Mishra G, Tiwari AK. Evaluation of advanced, pathophysiologic new targets for imaging of CNS. Drug Dev Res 2023; 84:484-513. [PMID: 36779375 DOI: 10.1002/ddr.22040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/12/2022] [Accepted: 12/31/2022] [Indexed: 02/14/2023]
Abstract
The inadequate information about the in vivo pathological, physiological, and neurological impairments, as well as the absence of in vivo tools for assessing brain penetrance and the efficiency of newly designed drugs, has hampered the development of new techniques for the treatment for variety of new central nervous system (CNS) diseases. The searching sites such as Science Direct and PubMed were used to find out the numerous distinct tracers across 16 CNS targets including tau, synaptic vesicle glycoprotein, the adenosine 2A receptor, the phosphodiesterase enzyme PDE10A, and the purinoceptor, among others. Among the most encouraging are [18 F]FIMX for mGluR imaging, [11 C]Martinostat for Histone deacetylase, [18 F]MNI-444 for adenosine 2A imaging, [11 C]ER176 for translocator protein, and [18 F]MK-6240 for tau imaging. We also reviewed the findings for each tracer's features and potential for application in CNS pathophysiology and therapeutic evaluation investigations, including target specificity, binding efficacy, and pharmacokinetic factors. This review aims to present a current evaluation of modern positron emission tomography tracers for CNS targets, with a focus on recent advances for targets that have newly emerged for imaging in humans.
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Affiliation(s)
- Priya Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Deepika Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Pooja Srivastava
- Division of Cyclotron and Radiopharmaceuticals Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Gauri Mishra
- Department of Zoology, Swami Shraddhananad College, University of Delhi, Alipur, Delhi, India
| | - Anjani K Tiwari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
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26
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Wang J, Moon SH, Cleary MB, Shoup TM, El Fakhri G, Zhang Z, Brownell AL. Detailed radiosynthesis of [ 18 F]mG4P027 as a positron emission tomography radiotracer for mGluR4. J Labelled Comp Radiopharm 2023; 66:34-40. [PMID: 36593743 PMCID: PMC9985952 DOI: 10.1002/jlcr.4011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/25/2022] [Accepted: 12/29/2022] [Indexed: 01/04/2023]
Abstract
We report here the detailed radiosynthesis of [18 F]mG4P027, a metabotropic glutamate receptor 4 (mGluR4) PET radiotracer, which showed superior properties to the currently reported mGluR4 radiotracers. The radiosynthesis in the automated system has been challenging, therefore we disclose here the major limiting factors for the synthesis via step-by-step examination. And we hope this thorough study will help its automation for human use in the future.
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Affiliation(s)
| | | | - Michael B. Cleary
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA)
| | | | | | - Zhaoda Zhang
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA)
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27
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Jiang M, Lu S, Telu S, Pike VW. An Empirical Quantitative Structure-Activity Relationship Equation Assists the Discovery of High-Affinity Phosphodiesterase 4D Inhibitors as Leads to PET Radioligands. J Med Chem 2023; 66:1543-1561. [PMID: 36608175 PMCID: PMC10433104 DOI: 10.1021/acs.jmedchem.2c01745] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A positron emission tomography (PET) radioligand for imaging phosphodiesterase 4D (PDE4D) would benefit drug discovery and the investigation of neuropsychiatric disorders. The most promising radioligand to date, namely, [11C]T1650, has shown unstable quantification in humans. Structural elaboration of [11C]T1650 was therefore deemed necessary. High target affinity in the low nM range is usually required for successful PET radioligands. In our PDE4D PET radioligand development, we formulated and optimized an empirical equation (log[IC50 (nM)] = P1 + P2 + P3 + P4) that well described the relationship between binding affinity and empirically derived values (P1-P4) for the individual fragments in four subregions commonly composing each inhibitor (R2 = 0.988, n = 62). This equation was used to predict compounds that would have high inhibitory potency. Fourteen new compounds were obtained with IC50 of 0.3-10 nM. Finally, eight compounds were judged to be worthy of future radiolabeling and evaluation as PDE4D PET radioligands.
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Affiliation(s)
- Meijuan Jiang
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1003, United States
| | - Shuiyu Lu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1003, United States
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1003, United States
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1003, United States
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28
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Bales B, Cotero V, Meyer DE, Roberts JC, Rodriguez-Silva M, Siclovan TM, Chambers JW, Rishel MJ. Radiolabeled Aminopyrazoles as Novel Isoform Selective Probes for pJNK3 Quantification. ACS Med Chem Lett 2022; 13:1606-1614. [PMID: 36262398 PMCID: PMC9575163 DOI: 10.1021/acsmedchemlett.2c00278] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 09/15/2022] [Indexed: 11/29/2022] Open
Abstract
The c-Jun N-terminal kinase 3 (JNK3) is a stress-activated kinase primarily expressed in the brain and implicated as an early mediator of neuronal apoptosis. We sought to develop a PET tracer to visualize pathological JNK3 activation. Because regional JNK3 activation precedes apoptosis, such an imaging agent might enable the detection of "at risk" brain regions prior to neuronal death. We prepared a set of 19F-containing compounds on the basis of the reported aminopyrazoles. The candidate, F3, was tritiated and used in autoradiography experiments to demonstrate regional and temporal changes in JNK3 activation in a mouse model of Parkinson's disease. A significant increase in pJNK3 B max versus control animals in multiple brain regions was observed at 8 months, including the ventral midbrain. Pathological activation of JNK3 in these regions preceded statistically significant neuron loss. Analyses of brain concentrations of [18F]-F3 in naïve rats following intravenous injection revealed a small but detectable signal over the background, but was likely not sufficient to support PET imaging.
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Affiliation(s)
- Brian
C. Bales
- Department
of Biology and Applied Physics, GE Research, One Research Circle, Niskayuna, New York 12309, United States
| | - Victoria Cotero
- Department
of Biology and Applied Physics, GE Research, One Research Circle, Niskayuna, New York 12309, United States
| | - Dan E. Meyer
- Department
of Biology and Applied Physics, GE Research, One Research Circle, Niskayuna, New York 12309, United States
| | - Jeannette C. Roberts
- Department
of Biology and Applied Physics, GE Research, One Research Circle, Niskayuna, New York 12309, United States
| | - Monica Rodriguez-Silva
- Department
of Environmental Health Sciences, Robert Stempel College of Public
Health & Social Work, Florida International
University, Miami, Florida 33199, United States
| | - Tiberiu M. Siclovan
- Department
of Biology and Applied Physics, GE Research, One Research Circle, Niskayuna, New York 12309, United States
| | - Jeremy W. Chambers
- Department
of Environmental Health Sciences, Robert Stempel College of Public
Health & Social Work, Florida International
University, Miami, Florida 33199, United States
| | - Michael J. Rishel
- Department
of Biology and Applied Physics, GE Research, One Research Circle, Niskayuna, New York 12309, United States
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29
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Auberson YP, Lièvre A, Desrayaud S, Briard E. A practical approach to the optimization of positron emission tomography (PET) imaging agents for the central nervous system. J Labelled Comp Radiopharm 2022; 65:343-350. [PMID: 36148533 DOI: 10.1002/jlcr.4004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 11/08/2022]
Abstract
The discovery of novel imaging agents for positron emission tomography (PET) relies on medicinal chemistry best practices, including a good understanding of molecular and pharmacological properties required for the acquisition of relevant, high-quality images. This short note reviews the characteristics of a series of clinically successful imaging agents, providing guidance for the optimization of such molecular tools. PET imaging plays an important role in staging disease and in helping clinical dose selection, which is critical for the efficient development of drug candidates.
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Affiliation(s)
- Yves P Auberson
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Akané Lièvre
- Novartis Institutes for BioMedical Research, Basel, Switzerland
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30
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Vercouillie J, Buron F, Sérrière S, Rodrigues N, Gulhan Z, Chartier A, Chicheri G, Marzag H, Oury A, Percina N, Bodard S, Ben Othman R, Busson J, Suzenet F, Guilloteau D, Marchivie M, Emond P, Routier S, Chalon S. Development and preclinical evaluation of [18F]FBVM as a new potent PET tracer for vesicular acetylcholine transporter. Eur J Med Chem 2022; 244:114794. [DOI: 10.1016/j.ejmech.2022.114794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 09/13/2022] [Accepted: 09/23/2022] [Indexed: 11/30/2022]
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31
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Shetty HU, Morse CL, Pike VW. Tandem Mass Spectrometry as an Independent Method for Corroborating Fluorine-18 Radioactivity Measurements in Positron Emission Tomography. ACS MEASUREMENT SCIENCE AU 2022; 2:370-376. [PMID: 35996540 PMCID: PMC9389646 DOI: 10.1021/acsmeasuresciau.2c00018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Positron emission tomography (PET) uses many tracers labeled with fluorine-18 (t 1/2 = 109.8 min; β+ 97%) for quantitative imaging of biochemical and physiological processes in animal and human subjects. In PET methodology, the radioactivity in a dose of an 18F-labeled tracer to be administered to a living subject is measured with a calibrated ionization chamber. This type of detector measures the radioactivity of a sample relative to those of certified amounts of longer-lived surrogate isotopes that are recommended for detector calibration. No alternative means for corroborating widely varying fluorine-18 radioactivity measurements from calibrated ionization chambers has been available. Here, we describe an independent nonradiometric method for this purpose. In this method, highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used to quantify the relative masses of the radioactive isotopologue ([18F]1) and the accompanying nonradioactive counterpart (carrier 1) in an 18F-labeled tracer preparation to give the mole ratio of [18F]1. High-performance liquid chromatography (HPLC) with a mass-calibrated absorbance detection is used alongside to provide a separate measurement of the aggregate mass of all isotopologues. The radioactivity of the radiotracer is then derived in becquerels (Bq) from these two measurements, plus Avogadro's number and the decay constant of fluorine-18. For the chosen example [18F]LSN3316612, the radioactivity values determined nonradiometrically and with a selected ionization chamber were in fair agreement. In addition, LC-MS/MS alone was found to provide an accurate measure of the half-life of fluorine-18.
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32
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Fu H, Rong J, Chen Z, Zhou J, Collier T, Liang SH. Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors. J Med Chem 2022; 65:10755-10808. [PMID: 35939391 DOI: 10.1021/acs.jmedchem.2c00633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.
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Affiliation(s)
- Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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33
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Viviano M, Barresi E, Siméon FG, Costa B, Taliani S, Da Settimo F, Pike VW, Castellano S. Essential Principles and Recent Progress in the Development of TSPO PET Ligands for Neuroinflammation Imaging. Curr Med Chem 2022; 29:4862-4890. [PMID: 35352645 PMCID: PMC10080361 DOI: 10.2174/0929867329666220329204054] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 12/21/2021] [Accepted: 01/25/2022] [Indexed: 11/22/2022]
Abstract
The translocator protein 18kDa (TSPO) is expressed in the outer mitochondrial membrane and is implicated in several functions, including cholesterol transport and steroidogenesis. Under normal physiological conditions, TSPO is present in very low concentrations in the human brain but is markedly upregulated in response to brain injury and inflammation. This upregulation is strongly associated with activated microglia. Therefore, TSPO is particularly suited for assessing active gliosis associated with brain lesions following injury or disease. For over three decades, TSPO has been studied as a biomarker. Numerous radioligands for positron emission tomography (PET) that target TSPO have been developed for imaging inflammatory progression in the brain. Although [11C]PK11195, the prototypical first-generation PET radioligand, is still widely used for in vivo studies, mainly now as its single more potent R-enantiomer, it has severe limitations, including low sensitivity and poor amenability to quantification. Second-generation radioligands are characterized by higher TSPO specific signals but suffer from other drawbacks, such as sensitivity to the TSPO single nucleotide polymorphism (SNP) rs6971. Therefore, their applications in human studies have the burden of needing to genotype subjects. Consequently, recent efforts are focused on developing improved radioligands that combine the optimal features of the second generation with the ability to overcome the differences in binding affinities across the population. This review presents essential principles in the design and development of TSPO PET ligands and discusses prominent examples among the main chemotypes.
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Affiliation(s)
- Monica Viviano
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy
| | | | - Fabrice G. Siméon
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Barbara Costa
- Department of Pharmacy, University of Pisa, 56126, Pisa, Italy
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, 56126, Pisa, Italy
| | | | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy
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34
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Yu Q, Kumata K, Rong J, Chen Z, Yamasaki T, Chen J, Xiao Z, Ishii H, Hiraishi A, Shao T, Zhang Y, Hu K, Xie L, Fujinaga M, Zhao C, Mori W, Collier T, Haider A, Tomita S, Zhang MR, Liang S. Imaging of Transmembrane AMPA Receptor Regulatory Proteins by Positron Emission Tomography. J Med Chem 2022; 65:9144-9158. [PMID: 35762919 PMCID: PMC10448436 DOI: 10.1021/acs.jmedchem.2c00377] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The transmembrane α-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic acid (AMPA) receptor regulatory protein γ-8 (TARP γ-8) constitutes an auxiliary subunit of AMPA receptors, which mediates various brain functions including learning and memory. TARP γ-8 has emerged as a promising therapeutic target for central nervous system disorders. Despite considerable efforts, previously reported TARP γ-8 PET radioligands, such as [11C]TARP-1903 and [11C]TARP-1811 series, were plagued by limited brain uptake and/or high nonspecific binding in vivo. Herein, we developed two novel 11C-labeled probes, [11C]8 and [11C]15 (also named as [11C]TARP-2105), of which the latter exhibited a reasonable brain uptake as well as specific binding toward TARP γ-8 both in vitro and in vivo, as confirmed by blocking experiments with the commercially available TARP γ-8 inhibitor, JNJ-55511118 in the TARP γ-8-rich hippocampus. Overall, [11C]15 exhibited promising tracer characteristics and proved to be a lead positron-emission tomography ligand for the non-invasive quantification of TARP γ-8 in the mammalian brain.
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Affiliation(s)
- Qingzhen Yu
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
- Medical Research Center, Southern University of Science and Technology Hospital & School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Katsushi Kumata
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Tomoteru Yamasaki
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Jiahui Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Zhiwei Xiao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Hideki Ishii
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Atsuto Hiraishi
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Tuo Shao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Yiding Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Kuan Hu
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Lin Xie
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Masayuki Fujinaga
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Chunyu Zhao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Wakana Mori
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, United States
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Steven Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
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35
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Yuan G, Dhaynaut M, Guehl NJ, Afshar S, Huynh D, Moon SH, Iyengar SM, Jain MK, Pickett JE, Kang HJ, Ondrechen MJ, El Fakhri G, Normandin MD, Brownell AL. Design, Synthesis, and Characterization of [ 18F]mG2P026 as a High-Contrast PET Imaging Ligand for Metabotropic Glutamate Receptor 2. J Med Chem 2022; 65:9939-9954. [PMID: 35802702 PMCID: PMC9434700 DOI: 10.1021/acs.jmedchem.2c00593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An array of triazolopyridines based on JNJ-46356479 (6) were synthesized as potential positron emission tomography radiotracers for metabotropic glutamate receptor 2 (mGluR2). The selected candidates 8-10 featured enhanced positive allosteric modulator (PAM) activity (20-fold max.) and mGluR2 agonist activity (25-fold max.) compared to compound 6 in the cAMP GloSensor assays. Radiolabeling of compounds 8 and 9 (mG2P026) was achieved via Cu-mediated radiofluorination with satisfactory radiochemical yield, >5% (non-decay-corrected); high molar activity, >180 GBq/μmol; and excellent radiochemical purity, >98%. Preliminary characterization of [18F]8 and [18F]9 in rats confirmed their excellent brain permeability and binding kinetics. Further evaluation of [18F]9 in a non-human primate confirmed its superior brain heterogeneity in mapping mGluR2 and higher affinity than [18F]6. Pretreatment with different classes of PAMs in rats and a primate led to similarly enhanced brain uptake of [18F]9. As a selective ligand, [18F]9 has the potential to be developed for translational studies.
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Affiliation(s)
- Gengyang Yuan
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Maeva Dhaynaut
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Nicolas J Guehl
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Sepideh Afshar
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Dalena Huynh
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Sung-Hyun Moon
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Suhasini M Iyengar
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Manish Kumar Jain
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Julie E Pickett
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Hye Jin Kang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Mary Jo Ondrechen
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Marc D Normandin
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Anna-Liisa Brownell
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
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36
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Jackson IM, Webb EW, Scott PJ, James ML. In Silico Approaches for Addressing Challenges in CNS Radiopharmaceutical Design. ACS Chem Neurosci 2022; 13:1675-1683. [PMID: 35606334 PMCID: PMC9945852 DOI: 10.1021/acschemneuro.2c00269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Positron emission tomography (PET) is a highly sensitive and versatile molecular imaging modality that leverages radiolabeled molecules, known as radiotracers, to interrogate biochemical processes such as metabolism, enzymatic activity, and receptor expression. The ability to probe specific molecular and cellular events longitudinally in a noninvasive manner makes PET imaging a particularly powerful technique for studying the central nervous system (CNS) in both health and disease. Unfortunately, developing and translating a single CNS PET tracer for clinical use is typically an extremely resource-intensive endeavor, often requiring synthesis and evaluation of numerous candidate molecules. While existing in vitro methods are beginning to address the challenge of derisking molecules prior to costly in vivo PET studies, most require a significant investment of resources and possess substantial limitations. In the context of CNS drug development, significant time and resources have been invested into the development and optimization of computational methods, particularly involving machine learning, to streamline the design of better CNS therapeutics. However, analogous efforts developed and validated for CNS radiotracer design are conspicuously limited. In this Perspective, we overview the requirements and challenges of CNS PET tracer design, survey the most promising computational methods for in silico CNS drug design, and bridge these two areas by discussing the potential applications and impact of computational design tools in CNS radiotracer design.
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Affiliation(s)
- Isaac M. Jackson
- Department of Radiology, Stanford University, Stanford, CA 94305
| | - E. William Webb
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109
| | - Peter J.H. Scott
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109;,Corresponding Authors: Peter J. H. Scott − Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States; , Michelle L. James − Departments of Radiology, and Neurology & Neurological Sciences, 1201 Welch Rd., P-206, Stanford, CA 94305-5484, United States;
| | - Michelle L. James
- Department of Radiology, Stanford University, Stanford, CA 94305;,Department of Neurology & Neurological Sciences, Stanford University, Stanford, CA 94304.,Corresponding Authors: Peter J. H. Scott − Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States; , Michelle L. James − Departments of Radiology, and Neurology & Neurological Sciences, 1201 Welch Rd., P-206, Stanford, CA 94305-5484, United States;
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37
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Kenou BV, Manly LS, Rubovits SB, Umeozulu SA, Van Buskirk MG, Zhang AS, Pike VW, Zanotti-Fregonara P, Henter ID, Innis RB. Cyclooxygenases as Potential PET Imaging Biomarkers to Explore Neuroinflammation in Dementia. J Nucl Med 2022; 63:53S-59S. [PMID: 35649646 DOI: 10.2967/jnumed.121.263199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 01/12/2022] [Indexed: 12/18/2022] Open
Abstract
The most frequently studied target of neuroinflammation using PET is 18-kDa translocator protein, but its limitations have spurred the molecular imaging community to find more promising targets. This article reviews the development of PET radioligands for cyclooxygenase (COX) subtypes 1 and 2, enzymes that catalyze the production of inflammatory prostanoids in the periphery and brain. Although both isozymes produce the same precursor compound, prostaglandin H2, they have distinct functions based on their differential cellular localization in the periphery and brain. For example, COX-1 is located primarily in microglia, a resident inflammatory cell in the brain whose role in producing inflammatory cytokines is well documented. In contrast, COX-2 is located primarily in neurons and can be markedly upregulated by inflammatory and excitatory stimuli, but its functions are poorly understood. This article reviews these 2 isozymes as biomarkers of neuroinflammation, as well as the radioligands that have recently been developed to image them in animals and humans. To place this work into context, the properties of COX-1 and COX-2 are compared with 18-kDa translocator protein, with special consideration of their application in Alzheimer disease as a representative neurodegenerative disorder.
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Affiliation(s)
- Bruny V Kenou
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Lester S Manly
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Sara B Rubovits
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Somachukwu A Umeozulu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Maia G Van Buskirk
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Andrea S Zhang
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Paolo Zanotti-Fregonara
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Ioline D Henter
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
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38
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Adhikari A, Pandey A, Kumar D, Tiwari AK. Determination of Hybrid TSPO Ligands with Minimal Impact of SNP
(rs6971) through Molecular Docking and MD Simulation Study. LETT DRUG DES DISCOV 2022. [DOI: 10.2174/1570180818666210413130326] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
In an endeavor to ascertain high-affinity TSPO ligands with minimal single
nucleotide polymorphism (SNP), six hybrid molecules have been identified as new leads for future
inflammation PET imaging.
Objective:
Genesis for chemical design was encouraged from structural families of well-known ligands
FEBMP and PBR28/ DAA1106 that have demonstrated remarkable TSPO binding characteristics.
Methods:
All proposed hybrid ligands 1-6 are subjected to molecular docking and simulation studies
with wild and mutant protein to study their interactions, binding, consistency of active conformations
and are correlated with well-established TSPO ligands.
Results:
Each hybrid ligand demonstrate better docking score > -11.00 kcal/mol with TSPO with
respect to gold standard PK11195, i.e., -11.00 kcal/mol for 4UC3 and -12.94 kcal/mol for 4UC1. On
comparison with FEBMP and GE-180 (-12.57, -7.24 kcal/mol for 4UC3 and -14.10, -11.32
kcal/mol for 4UC1), ligand 3 demonstrates maximum docking energy (> -15.50 kcal/mol) with
minimum SNP (0.26 kcal/mol).
Discussion:
Presence of strong hydrogen bond Arg148-3.27Å (4UC1) and Trp50-2.43Å, Asp28-
2.57Å (4UC3) apart from short-range interactions, including π–π interactions with the aromatic residues,
such as (Trp39, Phe46, Trp135) and (Trp39, Trp108), attributes towards its strong binding.
Conclusion:
Utilizing the results of binding energy, we concluded stable complex formation of these
hybrid ligands that could bind to TSPO with the least effect of SNP with similar interactions to
known ligands. Overall, ligand 3 stands out as the best ligand having insignificant deviations per
residue of protein that can be further explored and assessed in detail for future inflammation PET
application after subsequent detailed biological evaluation.
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Affiliation(s)
- Anupriya Adhikari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Anwesh Pandey
- Department of
Physics, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Devesh Kumar
- Department of
Physics, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Anjani K. Tiwari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
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39
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Synthesis, Biological Evaluation, and Docking Studies of Antagonistic Hydroxylated Arecaidine Esters Targeting mAChRs. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27103173. [PMID: 35630651 PMCID: PMC9145622 DOI: 10.3390/molecules27103173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/05/2022] [Accepted: 05/14/2022] [Indexed: 11/17/2022]
Abstract
The muscarinic acetylcholine receptor family is a highly sought-after target in drug and molecular imaging discovery efforts aimed at neurological disorders. Hampered by the structural similarity of the five subtypes’ orthosteric binding pockets, these efforts largely failed to deliver subtype-selective ligands. Building on our recent successes with arecaidine-derived ligands targeting M1, herein we report the synthesis of a related series of 11 hydroxylated arecaidine esters. Their physicochemical property profiles, expressed in terms of their computationally calculated CNS MPO scores and HPLC-logD values, point towards blood–brain barrier permeability. By means of a competitive radioligand binding assay, the binding affinity values towards each of the individual human mAChR subtypes hM1–hM5 were determined. The most promising compound of this series 17b was shown to have a binding constant towards hM1 in the single-digit nanomolar region (5.5 nM). Similar to our previously reported arecaidine-derived esters, the entire series was shown to act as hM1R antagonists in a calcium flux assay. Overall, this study greatly expanded our understanding of this recurring scaffolds’ structure–activity relationship and will guide the development towards highly selective mAChRs ligands.
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Novel plasma protein binding analysis method for a PET tracer and its radiometabolites: a case study with [11C]SMW139 to explain the high uptake of radiometabolites in mouse brain. J Pharm Biomed Anal 2022; 219:114860. [DOI: 10.1016/j.jpba.2022.114860] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 05/20/2022] [Accepted: 05/25/2022] [Indexed: 12/15/2022]
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Kikuchi T, Ogawa M, Okamura T, Gee AD, Zhang MR. Rapid 'on-column' preparation of hydrogen [ 11C]cyanide from [ 11C]methyl iodide via [ 11C]formaldehyde. Chem Sci 2022; 13:3556-3562. [PMID: 35432866 PMCID: PMC8943838 DOI: 10.1039/d1sc07033a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/01/2022] [Indexed: 11/21/2022] Open
Abstract
Hydrogen [11C]cyanide ([11C]HCN) is a versatile 11C-labelling agent for the production of 11C-labelled compounds used for positron emission tomography (PET). However, the traditional method for [11C]HCN production requires a dedicated infrastructure, limiting accessibility to [11C]HCN. Herein, we report a simple and efficient [11C]HCN production method that can be easily implemented in 11C production facilities. The immediate production of [11C]HCN was achieved by passing gaseous [11C]methyl iodide ([11C]CH3I) through a small two-layered reaction column. The first layer contained an N-oxide and a sulfoxide for conversion of [11C]CH3I to [11C]formaldehyde ([11C]CH2O). The [11C]CH2O produced was subsequently converted to [11C]HCN in a second layer containing hydroxylamine-O-sulfonic acid. The yield of [11C]HCN produced by the current method was comparable to that of [11C]HCN produced by the traditional method. The use of oxymatrine and diphenyl sulfoxide for [11C]CH2O production prevented deterioration of the molar activity of [11C]HCN. Using this method, compounds labelled with [11C]HCN are now made easily accessible for PET synthesis applications using readily available labware, without the need for the 'traditional' dedicated cyanide synthesis infrastructure.
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Affiliation(s)
- Tatsuya Kikuchi
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology 4-9-1 Anagawa, Inage-ku Chiba 263-8555 Japan
| | - Masanao Ogawa
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology 4-9-1 Anagawa, Inage-ku Chiba 263-8555 Japan
- SHI Accelerator Service, Ltd. 1-17-6 Osaki, Shinagawa-ku Tokyo 141-0032 Japan
| | - Toshimitsu Okamura
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology 4-9-1 Anagawa, Inage-ku Chiba 263-8555 Japan
| | - Antony D Gee
- School of Biomedical Engineering and Imaging Sciences, King's College London 4th Floor Lambeth Wing, St Thomas' Hospital, Lambeth Palace Road London SE1 7EH UK
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology 4-9-1 Anagawa, Inage-ku Chiba 263-8555 Japan
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Nerella SG, Singh P, Sanam T, Digwal CS. PET Molecular Imaging in Drug Development: The Imaging and Chemistry Perspective. Front Med (Lausanne) 2022; 9:812270. [PMID: 35295604 PMCID: PMC8919964 DOI: 10.3389/fmed.2022.812270] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/18/2022] [Indexed: 11/13/2022] Open
Abstract
Positron emission tomography with selective radioligands advances the drug discovery and development process by revealing information about target engagement, proof of mechanism, pharmacokinetic and pharmacodynamic profiles. Positron emission tomography (PET) is an essential and highly significant tool to study therapeutic drug development, dose regimen, and the drug plasma concentrations of new drug candidates. Selective radioligands bring up target-specific information in several disease states including cancer, cardiovascular, and neurological conditions by quantifying various rates of biological processes with PET, which are associated with its physiological changes in living subjects, thus it reveals disease progression and also advances the clinical investigation. This study explores the major roles, applications, and advances of PET molecular imaging in drug discovery and development process with a wide range of radiochemistry as well as clinical outcomes of positron-emitting carbon-11 and fluorine-18 radiotracers.
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Affiliation(s)
- Sridhar Goud Nerella
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Priti Singh
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Hyderabad, India
| | - Tulja Sanam
- Department of Microbiology and Applied Sciences, University of Agricultural Sciences, Bangalore, India
| | - Chander Singh Digwal
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Hyderabad, India
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Design, Synthesis, and Biological Evaluation of 4,4’-Difluorobenzhydrol Carbamates as Selective M1 Antagonists. Pharmaceuticals (Basel) 2022; 15:ph15020248. [PMID: 35215360 PMCID: PMC8879200 DOI: 10.3390/ph15020248] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/05/2022] [Accepted: 02/14/2022] [Indexed: 11/17/2022] Open
Abstract
Due to their important role in mediating a broad range of physiological functions, muscarinic acetylcholine receptors (mAChRs) have been a promising target for therapeutic and diagnostic applications alike; however, the list of truly subtype-selective ligands is scarce. Within this work, we have identified a series of twelve 4,4’-difluorobenzhydrol carbamates through a rigorous docking campaign leveraging commercially available amine databases. After synthesis, these compounds have been evaluated for their physico–chemical property profiles, including characteristics such as HPLC-logD, tPSA, logBB, and logPS. For all the synthesized carbamates, these characteristics indicate the potential for BBB permeation. In competitive radioligand binding experiments using Chinese hamster ovary cell membranes expressing the individual human mAChR subtype hM1-hM5, the most promising compound 2 displayed a high binding affinitiy towards hM1R (1.2 nM) while exhibiting modest-to-excellent selectivity versus the hM2-5R (4–189-fold). All 12 compounds were shown to act in an antagonistic fashion towards hM1R using a dose-dependent calcium mobilization assay. The structural eligibility for radiolabeling and their pharmacological and physico–chemical property profiles render compounds 2, 5, and 7 promising candidates for future position emission tomography (PET) tracer development.
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Yuan G, Dhaynaut M, Lan Y, Guehl NJ, Huynh D, Iyengar SM, Afshar S, Jain MK, Pickett JE, Kang HJ, Wang H, Moon SH, Ondrechen MJ, Wang C, Shoup TM, El Fakhri G, Normandin MD, Brownell AL. Synthesis and Characterization of 5-(2-Fluoro-4-[ 11C]methoxyphenyl)-2,2-dimethyl-3,4-dihydro-2 H-pyrano[2,3- b]pyridine-7-carboxamide as a PET Imaging Ligand for Metabotropic Glutamate Receptor 2. J Med Chem 2022; 65:2593-2609. [PMID: 35089713 PMCID: PMC9434702 DOI: 10.1021/acs.jmedchem.1c02004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metabotropic glutamate receptor 2 (mGluR2) is a therapeutic target for several neuropsychiatric disorders. An mGluR2 function in etiology could be unveiled by positron emission tomography (PET). In this regard, 5-(2-fluoro-4-[11C]methoxyphenyl)-2,2-dimethyl-3,4-dihydro-2H-pyrano[2,3-b]pyridine-7-carboxamide ([11C]13, [11C]mG2N001), a potent negative allosteric modulator (NAM), was developed to support this endeavor. [11C]13 was synthesized via the O-[11C]methylation of phenol 24 with a high molar activity of 212 ± 76 GBq/μmol (n = 5) and excellent radiochemical purity (>99%). PET imaging of [11C]13 in rats demonstrated its superior brain heterogeneity and reduced accumulation with pretreatment of mGluR2 NAMs, VU6001966 (9) and MNI-137 (26), the extent of which revealed a time-dependent drug effect of the blocking agents. In a nonhuman primate, [11C]13 selectively accumulated in mGluR2-rich regions and resulted in high-contrast brain images. Therefore, [11C]13 is a potential candidate for translational PET imaging of the mGluR2 function.
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Affiliation(s)
- Gengyang Yuan
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Maeva Dhaynaut
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Yu Lan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Nicolas J Guehl
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Dalena Huynh
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Suhasini M Iyengar
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Sepideh Afshar
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Manish Kumar Jain
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Julie E Pickett
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Hye Jin Kang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Hao Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Sung-Hyun Moon
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Mary Jo Ondrechen
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Timothy M Shoup
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Marc D Normandin
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
| | - Anna-Liisa Brownell
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 3rd Avenue, Charlestown, Massachusetts 02129, United States
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Vainio SK, Dickens AM, Matilainen M, López-Picón FR, Aarnio R, Eskola O, Solin O, Anthony DC, Rinne JO, Airas L, Haaparanta-Solin M. Dimethyl fumarate decreases short-term but not long-term inflammation in a focal EAE model of neuroinflammation. EJNMMI Res 2022; 12:6. [PMID: 35107664 PMCID: PMC8811048 DOI: 10.1186/s13550-022-00878-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 12/27/2021] [Indexed: 12/16/2022] Open
Abstract
Background Dimethyl fumarate (DMF) is an oral immunomodulatory drug used in the treatment of autoimmune diseases. Here, we sought to study whether the effect of DMF can be detected using positron emission tomography (PET) targeting the 18-kDa translocator protein (TSPO) in the focal delayed-type hypersensitivity rat model of multiple sclerosis (fDTH-EAE). The rats were treated orally twice daily from lesion activation (day 0) with either vehicle (tap water with 0.08% Methocel, 200 µL; control group n = 4 (3 after week four)) or 15 mg/kg DMF (n = 4) in 0.08% aqueous Methocel (200 µL) for 8 weeks. The animals were imaged by PET using the TSPO tracer [18F]GE-180 in weeks 0, 1, 2, 4, 8, and 18 following lesion activation, and the non-displaceable binding potential (BPND) was calculated. Immunohistochemical staining for Iba1, CD4, and CD8 was performed in week 18, and in separate cohorts of animals, following 2 or 4 weeks of treatment. Results Using the fDTH-EAE model, DMF reduced the [18F]GE-180 BPND in the DMF-treated animals compared to control animals after 1 week of treatment (two-tailed unpaired t test, p = 0.031), but not in weeks 2, 4, 8, or 18 when imaged in vivo by PET. Immunostaining for Iba1 showed that DMF had no effect on the perilesional volume or the core lesion volume after 2 or 4 weeks of treatment, or at 18 weeks. However, the optical density (OD) measurements of CD4+ staining showed reduced OD in the lesions of the treated rats. Conclusions DMF reduced the microglial activation in the fDTH-EAE model after 1 week of treatment, as detected by PET imaging of the TSPO ligand [18F]GE-180. However, over an extended time course, reduced microglial activation was not observed using [18F]GE-180 or by immunohistochemistry for Iba1+ microglia/macrophages. Additionally, DMF did affect the infiltration of CD4+ and CD8+ T-lymphocytes at the fDTH-EAE lesion. Supplementary Information The online version contains supplementary material available at 10.1186/s13550-022-00878-y. In a focal rat DTH-EAE model of neuroinflammation, dimethyl fumarate decreases the uptake of TSPO PET tracer [18F]GE-180 in the short term. Long-term [18F]GE-180 follow-up did not indicate a treatment effect. Decreased neuroinflammation, CD4+ T cell infiltration, and CD8+ T cell infiltration were detected using immunohistochemistry.
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Affiliation(s)
- S K Vainio
- Turku PET Centre, Preclinical PET Imaging, Preclinical Imaging Laboratory, University of Turku, Tykistökatu 6 A, 20520, Turku, Finland. .,MediCity Research Laboratory, University of Turku, Turku, Finland.
| | - A M Dickens
- Department of Chemistry, University of Turku, Turku, Finland.,Turku Bioscience, Turku, Finland
| | - M Matilainen
- Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.,Turku PET Centre, University of Turku, Turku, Finland
| | - F R López-Picón
- Turku PET Centre, Preclinical PET Imaging, Preclinical Imaging Laboratory, University of Turku, Tykistökatu 6 A, 20520, Turku, Finland.,MediCity Research Laboratory, University of Turku, Turku, Finland
| | - R Aarnio
- MediCity Research Laboratory, University of Turku, Turku, Finland.,Turku PET Centre, University of Turku, Turku, Finland
| | - O Eskola
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland
| | - O Solin
- Accelerator Laboratory, Åbo Akademi University, Turku, Finland.,Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland
| | - D C Anthony
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - J O Rinne
- Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland.,Turku PET Centre, University of Turku, Turku, Finland
| | - L Airas
- Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland.,Department of Clinical Medicine, University of Turku, Turku, Finland
| | - M Haaparanta-Solin
- Turku PET Centre, Preclinical PET Imaging, Preclinical Imaging Laboratory, University of Turku, Tykistökatu 6 A, 20520, Turku, Finland.,MediCity Research Laboratory, University of Turku, Turku, Finland
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Sun X, Admane P, Starosolski ZA, Eriksen JL, Annapragada AV, Tanifum EA. 1-Indanone and 1,3-indandione Derivatives as Ligands for Misfolded α-Synuclein Aggregates. ChemMedChem 2022; 17:e202100611. [PMID: 34704363 PMCID: PMC8770581 DOI: 10.1002/cmdc.202100611] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/22/2021] [Indexed: 01/21/2023]
Abstract
The development of imaging agents for in vivo detection of alpha-synuclein (α-syn) pathologies faces several challenges. A major gap in the field is the lack of diverse molecular scaffolds with high affinity and selectivity to α-syn fibrils for in vitro screening assays. Better in vitro scaffolds can instruct the discovery of better in vivo agents. We report the rational design, synthesis, and in vitro evaluation of a series of novel 1-indanone and 1,3-indandione derivatives from a Structure-Activity Relationship (SAR) study centered on some existing α-syn fibril binding ligands. Our results from fibril saturation binding experiments show that two of the lead candidates compounds 8 and 32 bind α-syn fibrils with binding constants (Kd ) of 9.0 and 18.8 nM, respectively, and selectivity of greater than 10× for α-syn fibrils compared with amyloid-β (Aβ) and tau fibrils. Our results demonstrate that the lead ligands avidly label all forms of α-syn on PD brain tissue sections, but only the dense core of senile plaques in AD brain tissue, respectively. These results are corroborated by ligand-antibody colocalization data from Syn211, which shows immunoreactivity toward all forms of α-syn aggregates, and Syn303, which displays preferential reactivity toward mature Lewy pathology. Our results reveal that 1-indanone derivatives have desirable properties for the biological evaluation of α-synucleinopathies.
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Affiliation(s)
- Xianwei Sun
- Department of Radiology, Baylor College of Medicine, Houston, TX 77030 (USA)
| | - Prasad Admane
- Department of Radiology, Baylor College of Medicine, Houston, TX 77030 (USA)
| | - Zbigniew A. Starosolski
- Department of Radiology, Baylor College of Medicine, Houston, TX 77030 (USA)
- Edward B. Singleton Department of Radiology, Texas Children's Hospital, Houston, Texas 77030 (USA)
| | - Jason L. Eriksen
- College of Pharmacy, Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204 (USA)
| | - Ananth V. Annapragada
- Department of Radiology, Baylor College of Medicine, Houston, TX 77030 (USA)
- Edward B. Singleton Department of Radiology, Texas Children's Hospital, Houston, Texas 77030 (USA)
| | - Eric A. Tanifum
- Department of Radiology, Baylor College of Medicine, Houston, TX 77030 (USA)
- Edward B. Singleton Department of Radiology, Texas Children's Hospital, Houston, Texas 77030 (USA)
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Imaging Histamine H3 Receptors with Positron Emission Tomography. Curr Top Behav Neurosci 2021; 59:147-167. [PMID: 34964937 DOI: 10.1007/7854_2021_285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Positron emission tomography (PET) provides a unique tool to study the biochemistry of the human brain in vivo. By using PET probes that are binding selectively to certain receptor subtypes, brain PET allows the quantification of receptor levels in various brain areas of human subjects. This approach has the potential to reveal abnormal receptor expressions that may contribute to the physiopathology of some psychiatric and neurological disorders. This approach also has the potential to assist in the drug development process by determining receptor occupancy in vivo allowing selection of proper drug dosage to produce therapeutic effects. Several PET tracers have been developed for histamine H3 receptors (H3R). However, despite the potential of PET to elucidate the role of H3R in vivo, only limited work has been conducted so far. This article reviews the work that has been done in this area. Notably, we will cover the limitations of the first-generation PET radioligand for H3R and present the advantages of novel radioligands that promise an explosion of clinical PET research on the role of H3R in vivo.
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Siméon FG, Lee JH, Morse CL, Stukes I, Zoghbi SS, Manly LS, Liow JS, Gladding RL, Dick RM, Yan X, Taliani S, Costa B, Martini C, Da Settimo F, Castellano S, Innis RB, Pike VW. Synthesis and Screening in Mice of Fluorine-Containing PET Radioligands for TSPO: Discovery of a Promising 18F-Labeled Ligand. J Med Chem 2021; 64:16731-16745. [PMID: 34756026 PMCID: PMC8817670 DOI: 10.1021/acs.jmedchem.1c01562] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Translocator protein 18 kDa (TSPO) is a biomarker of neuroinflammation. [11C]ER176 robustly quantifies TSPO in the human brain with positron emission tomography (PET), irrespective of subject genotype. We aimed to develop an ER176 analog with potential for labeling with longer-lived fluorine-18 (t1/2 = 109.8 min). New fluoro and trifluoromethyl analogs of ER176 were prepared through a concise synthetic strategy. These ligands showed high TSPO affinity and low human genotype sensitivity. Each ligand was initially labeled by a generic 11C-methylation procedure, thereby enabling speedy screening in mice. Each radioligand was rapidly taken up and well retained in the mouse brain at baseline after intravenous injection. Preblocking of TSPO showed that high proportions of brain uptake were specifically bound to TSPO at baseline. Overall, the 3-fluoro analog of [11C]ER176 ([11C]3b) displayed the most promising imaging properties. Therefore, a method was developed to label 3b with [18F]fluoride ion. [18F]3b gave similarly promising PET imaging results and deserves evaluation in higher species.
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Affiliation(s)
- Fabrice G Siméon
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jae-Hoon Lee
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
- Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 03772, South Korea
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Ian Stukes
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Lester S Manly
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Robert L Gladding
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Rachel M Dick
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Xuefeng Yan
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | - Barbara Costa
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | - Claudia Martini
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | | | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, 84084 Fisciano, SA, Italy
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
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Preliminary Assessment of the Anti-inflammatory Activity of New Structural Honokiol Analogs with a 4'- O-(2-Fluoroethyl) Moiety and the Potential of Their 18F-Labeled Derivatives for Neuroinflammation Imaging. Molecules 2021; 26:molecules26216630. [PMID: 34771039 PMCID: PMC8587714 DOI: 10.3390/molecules26216630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/24/2021] [Accepted: 10/28/2021] [Indexed: 01/31/2023] Open
Abstract
Neolignans honokiol and 4′-O-methylhonokiol (MH) and their derivatives have pronounced anti-inflammatory activity, as evidenced by numerous pharmacological studies. Literature data suggested that cyclooxygenase type 2 (COX-2) may be a target for these compounds in vitro and in vivo. Recent studies of [11C]MPbP (4′-[11C]methoxy-5-propyl-1,1′-biphenyl-2-ol) biodistribution in LPS (lipopolysaccharide)-treated rats have confirmed the high potential of MH derivatives for imaging neuroinflammation. Here, we report the synthesis of four structural analogs of honokiol, of which 4′-(2-fluoroethoxy)-2-hydroxy-5-propyl-1, 1′-biphenyl (F-IV) was selected for labeling with fluorine-18 (T1/2 = 109.8 min) due to its high anti-inflammatory activity confirmed by enzyme immunoassays (EIA) and neuromorphological studies. The high inhibitory potency of F-IV to COX-2 and its moderate lipophilicity and chemical stability are favorable factors for the preliminary evaluation of the radioligand [18F]F-IV in a rodent model of neuroinflammation. [18F]F-IV was prepared with good radiochemical yield and high molar activity and radiochemical purity by 18F-fluoroethylation of the precursor with Boc-protecting group (15) with [18F]2-fluoro-1-bromoethane ([18F]FEB). Ex vivo biodistribution studies revealed a small to moderate increase in radioligand uptake in the brain and peripheral organs of LPS-induced rats compared to control animals. Pretreatment with celecoxib resulted in significant blocking of radioactivity uptake in the brain (pons and medulla), heart, lungs, and kidneys, indicating that [18F]F-IV is likely to specifically bind to COX-2 in a rat model of neuroinflammation. However, in comparison with [11C]MPbP, the new radioligand showed decreased brain uptake in LPS rats and high retention in the blood pool, which apparently could be explained by its high plasma protein binding. We believe that the structure of [18F]F-IV can be optimized by replacing the substituents in the biphenyl core to eliminate these disadvantages and develop new radioligands for imaging activated microglia.
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Positron emission tomography in multiple sclerosis - straight to the target. Nat Rev Neurol 2021; 17:663-675. [PMID: 34545219 DOI: 10.1038/s41582-021-00537-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2021] [Indexed: 02/08/2023]
Abstract
Following the impressive progress in the treatment of relapsing-remitting multiple sclerosis (MS), the major challenge ahead is the development of treatments to prevent or delay the irreversible accumulation of clinical disability in progressive forms of the disease. The substrate of clinical progression is neuro-axonal degeneration, and a deep understanding of the mechanisms that underlie this process is a precondition for the development of therapies for progressive MS. PET imaging involves the use of radiolabelled compounds that bind to specific cellular and metabolic targets, thereby enabling direct in vivo measurement of several pathological processes. This approach can provide key insights into the clinical relevance of these processes and their chronological sequence during the disease course. In this Review, we focus on the contribution that PET is making to our understanding of extraneuronal and intraneuronal mechanisms that are involved in the pathogenesis of irreversible neuro-axonal damage in MS. We consider the major challenges with the use of PET in MS and the steps necessary to realize clinical benefits of the technique. In addition, we discuss the potential of emerging PET tracers and future applications of existing compounds to facilitate the identification of effective neuroprotective treatments for patients with MS.
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