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Kaur T, Brooks AF, Lapsys A, Desmond TJ, Stauff J, Arteaga J, Winton WP, Scott PJH. Synthesis and Evaluation of a Fluorine-18 Radioligand for Imaging Huntingtin Aggregates by Positron Emission Tomographic Imaging. Front Neurosci 2021; 15:766176. [PMID: 34924935 PMCID: PMC8675899 DOI: 10.3389/fnins.2021.766176] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in the huntingtin gene (HTT) triggers aggregation of huntingtin protein (mHTT), which is the hallmark pathology of neurodegenerative Huntington's disease (HD). Development of a high affinity 18F radiotracer would enable the study of Huntington's disease pathology using a non-invasive imaging modality, positron emission tomography (PET) imaging. Herein, we report the first synthesis of fluorine-18 imaging agent, 6-(5-((5-(2,2-difluoro-2-(fluoro-18F)ethoxy)pyridin-2-yl)methoxy)benzo[d]oxazol-2-yl)-2-methylpyridazin-3(2H)-one ([18F]1), a radioligand for HD and its preclinical evaluation in vitro (autoradiography of post-mortem HD brains) and in vivo (rodent and non-human primate brain PET). [18F]1 was synthesized in a 4.1% RCY (decay corrected) and in an average molar activity of 16.5 ± 12.5 GBq/μmol (445 ± 339 Ci/mmol). [18F]1 penetrated the blood-brain barrier of both rodents and primates, and specific saturable binding in post-mortem brain slices was observed that correlated to mHTT aggregates identified by immunohistochemistry.
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Affiliation(s)
| | | | | | | | | | | | | | - Peter J. H. Scott
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
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2
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Sun J, Xiao Z, Haider A, Gebhard C, Xu H, Luo HB, Zhang HT, Josephson L, Wang L, Liang SH. Advances in Cyclic Nucleotide Phosphodiesterase-Targeted PET Imaging and Drug Discovery. J Med Chem 2021; 64:7083-7109. [PMID: 34042442 DOI: 10.1021/acs.jmedchem.1c00115] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cyclic nucleotide phosphodiesterases (PDEs) control the intracellular concentrations of cAMP and cGMP in virtually all mammalian cells. Accordingly, the PDE family regulates a myriad of physiological functions, including cell proliferation, differentiation and apoptosis, gene expression, central nervous system function, and muscle contraction. Along this line, dysfunction of PDEs has been implicated in neurodegenerative disorders, coronary artery diseases, chronic obstructive pulmonary disease, and cancer development. To date, 11 PDE families have been identified; however, their distinct roles in the various pathologies are largely unexplored and subject to contemporary research efforts. Indeed, there is growing interest for the development of isoform-selective PDE inhibitors as potential therapeutic agents. Similarly, the evolving knowledge on the various PDE isoforms has channeled the identification of new PET probes, allowing isoform-selective imaging. This review highlights recent advances in PDE-targeted PET tracer development, thereby focusing on efforts to assess disease-related PDE pathophysiology and to support isoform-selective drug discovery.
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Affiliation(s)
- Jiyun Sun
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Zhiwei Xiao
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Ahmed Haider
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Catherine Gebhard
- Department of Nuclear Medicine, University Hospital Zurich, Raemistrasse 100, Zurich 8006, Switzerland.,Center for Molecular Cardiology, University of Zurich, Wagistrasse 12, Schlieren 8952, Switzerland
| | - Hao Xu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Hai-Bin Luo
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Han-Ting Zhang
- Departments of Neuroscience, Behavioral Medicine & Psychiatry, and Physiology & Pharmacology, the Rockefeller Neuroscience Institute, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506, United States
| | - Lee Josephson
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Lu Wang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States.,Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Steven H Liang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
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3
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Schopf E, Waldmann CM, Collins J, Drake C, Slavik R, van Dam RM. Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production. J Vis Exp 2018. [PMID: 30417868 PMCID: PMC6235612 DOI: 10.3791/58428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological targets and processes. However, the increasing number of different tracers creates challenges for their production at radiopharmacies. While historically it has been practical to dedicate a custom-configured radiosynthesizer and hot cell for the repeated production of each individual tracer, it is becoming necessary to change this workflow. Recent commercial radiosynthesizers based on disposable cassettes/kits for each tracer simplify the production of multiple tracers with one set of equipment by eliminating the need for custom tracer-specific modifications. Furthermore, some of these radiosynthesizers enable the operator to develop and optimize their own synthesis protocols in addition to purchasing commercially-available kits. In this protocol, we describe the general procedure for how the manual synthesis of a new PET tracer can be automated on one of these radiosynthesizers and validated for the production of clinical-grade tracers. As an example, we use the ELIXYS radiosynthesizer, a flexible cassette-based radiochemistry tool that can support both PET tracer development efforts, as well as routine clinical probe manufacturing on the same system, to produce [18F]Clofarabine ([18F]CFA), a PET tracer to measure in vivo deoxycytidine kinase (dCK) enzyme activity. Translating a manual synthesis involves breaking down the synthetic protocol into basic radiochemistry processes that are then translated into intuitive chemistry "unit operations" supported by the synthesizer software. These operations can then rapidly be converted into an automated synthesis program by assembling them using the drag-and-drop interface. After basic testing, the synthesis and purification procedure may require optimization to achieve the desired yield and purity. Once the desired performance is achieved, a validation of the synthesis is carried out to determine its suitability for the production of the radiotracer for clinical use.
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Affiliation(s)
| | - Christopher M Waldmann
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles (UCLA); Ahmanson Translational Imaging Division, University of California, Los Angeles (UCLA)
| | - Jeffrey Collins
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles (UCLA); Crump Institute for Molecular Imaging, University of California, Los Angeles (UCLA)
| | | | - Roger Slavik
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles (UCLA); Ahmanson Translational Imaging Division, University of California, Los Angeles (UCLA);
| | - R Michael van Dam
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles (UCLA); Crump Institute for Molecular Imaging, University of California, Los Angeles (UCLA);
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4
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Fan HT, Guo JF, Zhang YX, Gu YX, Ning ZQ, Qiao YJ, Wang X. The rational search for PDE10A inhibitors from Sophora flavescens roots using pharmacophore‑ and docking‑based virtual screening. Mol Med Rep 2017; 17:388-393. [PMID: 29115449 DOI: 10.3892/mmr.2017.7871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 08/31/2017] [Indexed: 11/06/2022] Open
Abstract
Phosphodiesterase 10A (PDE10A) has been confirmed to be an important target for the treatment of central nervous system (CNS) disorders. The purpose of the present study was to identify PDE10A inhibitors from herbs used in traditional Chinese medicine. Pharmacophore and molecular docking techniques were used to virtually screen the chemical molecule database of Sophora flavescens, a well‑known Chinese herb that has been used for improving mental health and regulating the CNS. The pharmacophore model generated recognized the common functional groups of known PDE10A inhibitors. In addition, molecular docking was used to calculate the binding affinity of ligand‑PDE10A interactions and to investigate the possible binding pattern. Virtual screening based on the pharmacophore model and molecular docking was performed to identify potential PDE10A inhibitors from S. flavescens. The results demonstrated that nine hits from S. flavescens were potential PDE10A inhibitors, and their biological activity was further validated using literature mining. A total of two compounds were reported to inhibit cyclic adenosine monophosphate phosphodiesterase, and one protected against glutamate‑induced oxidative stress in the CNS. The remaining six compounds require further bioactivity validation. The results of the present study demonstrated that this method was a time‑ and cost‑saving strategy for the identification of bioactive compounds from traditional Chinese medicine.
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Affiliation(s)
- Han-Tian Fan
- School of Traditional Chinese Medicine, Capital Medical University, Beijing 100069, P.R. China
| | - Jun-Fang Guo
- School of Traditional Chinese Medicine, Capital Medical University, Beijing 100069, P.R. China
| | - Yu-Xin Zhang
- Key Laboratory of TCM‑Information Engineer of State Administration of TCM, School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100102, P.R. China
| | - Yu-Xi Gu
- School of Traditional Chinese Medicine, Capital Medical University, Beijing 100069, P.R. China
| | - Zhong-Qi Ning
- School of Traditional Chinese Medicine, Capital Medical University, Beijing 100069, P.R. China
| | - Yan-Jiang Qiao
- Key Laboratory of TCM‑Information Engineer of State Administration of TCM, School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100102, P.R. China
| | - Xing Wang
- School of Traditional Chinese Medicine, Capital Medical University, Beijing 100069, P.R. China
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Abstract
PURPOSE A positron emission tomography (PET) tracer for the enzyme phosphodiesterase 10A (PDE10A) is desirable to guide the discovery and development of PDE10A inhibitors as potential therapeutics. The preclinical characterization of the PDE10A PET tracer [(11)C]MK-8193 is described. PROCEDURES In vitro binding studies with [(3)H]MK-8193 were conducted in rat, monkey, and human brain tissue. PET studies with [(11)C]MK-8193 were conducted in rats and rhesus monkeys at baseline and following administration of a PDE10A inhibitor. RESULTS [(3)H]MK-8193 is a high-affinity, selective PDE10A radioligand in rat, monkey, and human brain tissue. In vivo, [(11)C]MK-8193 displays rapid kinetics, low test-retest variability, and a large specific signal that is displaced by a structurally diverse PDE10A inhibitor, enabling the determination of pharmacokinetic/enzyme occupancy relationships. CONCLUSIONS [(11)C]MK-8193 is a useful PET tracer for the preclinical characterization of PDE10A therapeutic candidates in rat and monkey. Further evaluation of [(11)C]MK-8193 in humans is warranted.
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Tan J, Zheng T, Yu Y, Xu K. TBHP-promoted direct oxidation reaction of benzylic Csp3–H bonds to ketones. RSC Adv 2017. [DOI: 10.1039/c7ra00352h] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A metal-free oxidation system employingtert-butyl hydroperoxide (TBHP) has been developed for selective oxidation of structurally diverse benzylic sp3C–H bonds.
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Affiliation(s)
- Jiajing Tan
- Department of Organic Chemistry
- Faculty of Science
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Tianyu Zheng
- Department of Organic Chemistry
- Faculty of Science
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Yuqi Yu
- China Academy of Engineering Physics
- Mianyang
- China
| | - Kun Xu
- College of Chemistry and Pharmaceutical Engineering
- Nanyang Normal University
- Nanyang
- P. R. China
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7
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Geerts H, Spiros A, Roberts P. Phosphodiesterase 10 inhibitors in clinical development for CNS disorders. Expert Rev Neurother 2016; 17:553-560. [DOI: 10.1080/14737175.2017.1268531] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Hugo Geerts
- In Silico Biosciences Perelman School of Medicine, University of Pennsylvania, Berwyn, PA, USA
| | - Athan Spiros
- In Silico Biosciences Perelman School of Medicine, University of Pennsylvania, Berwyn, PA, USA
| | - Patrick Roberts
- In Silico Biosciences Perelman School of Medicine, University of Pennsylvania, Berwyn, PA, USA
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Wagner S, Teodoro R, Deuther-Conrad W, Kranz M, Scheunemann M, Fischer S, Wenzel B, Egerland U, Hoefgen N, Steinbach J, Brust P. Radiosynthesis and biological evaluation of the new PDE10A radioligand [ 18 F]AQ28A. J Labelled Comp Radiopharm 2016; 60:36-48. [PMID: 27896836 DOI: 10.1002/jlcr.3471] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/19/2016] [Accepted: 10/12/2016] [Indexed: 01/10/2023]
Abstract
Cyclic nucleotide phosphodiesterase 10A (PDE10A) regulates the level of the second messengers cAMP and cGMP in particular in brain regions assumed to be associated with neurodegenerative and psychiatric diseases. A better understanding of the pathophysiological role of the expression of PDE10A could be obtained by quantitative imaging of the enzyme by positron emission tomography (PET). Thus, in this study we developed, radiolabeled, and evaluated a new PDE10A radioligand, 8-bromo-1-(6-[18 F]fluoropyridin-3-yl)-3,4-dimethylimidazo[1,5-a]quinoxaline ([18 F]AQ28A). [18 F]AQ28A was radiolabeled by both nucleophilic bromo-to-fluoro or nitro-to-fluoro exchange using K[18 F]F-K2.2.2 -carbonate complex with different yields. Using the superior nitro precursor, we developed an automated synthesis on a Tracerlab FX F-N module and obtained [18 F]AQ28A with high radiochemical yields (33 ± 6%) and specific activities (96-145 GBq·μmol-1 ) for further evaluation. Initially, we investigated the binding of [18 F]AQ28A to the brain of different species by autoradiography and observed the highest density of binding sites in striatum, the brain region with the highest PDE10A expression. Subsequent dynamic PET studies in mice revealed a region-specific accumulation of [18 F]AQ28A in this region, which could be blocked by preinjection of the selective PDE10A ligand MP-10. In conclusion, the data suggest [18 F]AQ28A is a suitable candidate for imaging of PDE10A in rodent brain by PET.
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Affiliation(s)
- Sally Wagner
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Matthias Scheunemann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | | | | | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals, Leipzig, Germany
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Hennenberg M, Schott M, Kan A, Keller P, Tamalunas A, Ciotkowska A, Rutz B, Wang Y, Strittmatter F, Herlemann A, Yu Q, Stief CG, Gratzke C. Inhibition of Adrenergic and Non-Adrenergic Smooth Muscle Contraction in the Human Prostate by the Phosphodiesterase 10-Selective Inhibitor TC-E 5005. Prostate 2016; 76:1364-74. [PMID: 27418235 DOI: 10.1002/pros.23208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/09/2016] [Indexed: 01/03/2023]
Abstract
BACKGROUND The phosphodiesterase (PDE) 5 inhibitor tadalafil is available for treatment of male lower urinary tract symptoms (LUTS), while the role of other PDE isoforms for prostate smooth muscle tone is still unknown. Here, we examined effects of the PDE10-selective inhibitor TC-E 5005 on smooth muscle contraction in human prostate tissue. METHODS Prostate samples were obtained from patients undergoing radical prostatectomy. Expression of PDE10 was addressed by RT-PCR, Western blot, and fluorescence staining with different markers. Effects of TC-E 5005 and tadalafil on contraction, and relaxation of prostate strips were studied via organ bath. RESULTS PDE10A was detectable by RT-PCR, Western blot, and fluorescence staining in prostate tissues. Colocalization with markers suggested expression of PDE10A in smooth muscle cells and catecholaminergic nerves. Norepinephrine, the α1 -adrenergic agonist phenylephrine, the thromboxane A2 analogue U46619, and endothelins 1-3 induced concentration-dependent contractions of prostate strips, while electric field stimulation (EFS) induced frequence-dependent contractions. Application of TC-E 5005 (500 nM) caused significant inhibition of norepinephrine-, phenylephrine-, and endothelin-3-induced contractions. Inhibition of EFS-induced contractions by TC-E 5005 ranged around 50%, resembling inhibition of EFS-induced contractions by tadalafil (10 μM). The prostacyclin analog treprostinil and the nitric oxide donor DEA NONOate induced relaxations of precontracted prostate strips, which were significantly amplified by TCE 5005. CONCLUSIONS The PDE10-selective inhibitor TC-E 5005 inhibits adrenergic and neurogenic smooth muscle contractions in the human prostate. TC-E 5005 inhibits neurogenic contractions with similar efficacy than tadalafil, so that urodynamic effects in vivo appear possible. Prostate 76:1364-1374, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Martin Hennenberg
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Melanie Schott
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Aysenur Kan
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Patrick Keller
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | | | - Anna Ciotkowska
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Beata Rutz
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Yiming Wang
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | | | - Annika Herlemann
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Qingfeng Yu
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Christian G Stief
- Department of Urology, Ludwig-Maximilians University, Munich, Germany
| | - Christian Gratzke
- Department of Urology, Ludwig-Maximilians University, Munich, Germany.
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Hu E, Chen N, Kunz RK, Hwang DR, Michelsen K, Davis C, Ma J, Shi J, Lester-Zeiner D, Hungate R, Treanor J, Chen H, Allen JR. Discovery of Phosphodiesterase 10A (PDE10A) PET Tracer AMG 580 to Support Clinical Studies. ACS Med Chem Lett 2016; 7:719-23. [PMID: 27437084 DOI: 10.1021/acsmedchemlett.6b00185] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 05/19/2016] [Indexed: 11/29/2022] Open
Abstract
We report the discovery of PDE10A PET tracer AMG 580 developed to support proof of concept studies with PDE10A inhibitors in the clinic. To find a tracer with higher binding potential (BPND) in NHP than our previously reported tracer 1, we implemented a surface plasmon resonance assay to measure the binding off-rate to identify candidates with slower washout rate in vivo. Five candidates (2-6) from two structurally distinct scaffolds were identified that possessed both the in vitro characteristics that would favor central penetration and the structural features necessary for PET isotope radiolabeling. Two cinnolines (2, 3) and one keto-benzimidazole (5) exhibited PDE10A target specificity and brain uptake comparable to or better than 1 in the in vivo LC-MS/MS kinetics distribution study in SD rats. In NHP PET imaging study, [(18)F]-5 produced a significantly improved BPND of 3.1 and was nominated as PDE10A PET tracer clinical candidate for further studies.
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Affiliation(s)
| | | | | | | | - Klaus Michelsen
- Department
of Molecular Structure and Characterization, Amgen Inc., 360 Binney
Street, Cambridge, Massachusetts 02142, United States
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11
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Novel Radioligands for Cyclic Nucleotide Phosphodiesterase Imaging with Positron Emission Tomography: An Update on Developments Since 2012. Molecules 2016; 21:molecules21050650. [PMID: 27213312 PMCID: PMC6273803 DOI: 10.3390/molecules21050650] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/09/2016] [Accepted: 05/10/2016] [Indexed: 12/19/2022] Open
Abstract
Cyclic nucleotide phosphodiesterases (PDEs) are a class of intracellular enzymes that inactivate the secondary messenger molecules, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Thus, PDEs regulate the signaling cascades mediated by these cyclic nucleotides and affect fundamental intracellular processes. Pharmacological inhibition of PDE activity is a promising strategy for treatment of several diseases. However, the role of the different PDEs in related pathologies is not completely clarified yet. PDE-specific radioligands enable non-invasive visualization and quantification of these enzymes by positron emission tomography (PET) in vivo and provide an important translational tool for elucidation of the relationship between altered expression of PDEs and pathophysiological effects as well as (pre-)clinical evaluation of novel PDE inhibitors developed as therapeutics. Herein we present an overview of novel PDE radioligands for PET published since 2012.
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12
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Li J, Zhang X, Jin H, Fan J, Flores H, Perlmutter JS, Tu Z. Synthesis of Fluorine-Containing Phosphodiesterase 10A (PDE10A) Inhibitors and the In Vivo Evaluation of F-18 Labeled PDE10A PET Tracers in Rodent and Nonhuman Primate. J Med Chem 2015; 58:8584-600. [PMID: 26430878 DOI: 10.1021/acs.jmedchem.5b01205] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A series of fluorine-containing PDE10A inhibitors were designed and synthesized to improve the metabolic stability of [(11)C]MP-10. Twenty of the 22 new analogues had high potency and selectivity for PDE10A: 18a-j, 19d-j, 20a-b, and 21b had IC50 values <5 nM for PDE10A. Seven F-18 labeled compounds [(18)F]18a-e, [(18)F]18g, and [(18)F]20a were radiosynthesized by (18)F-introduction onto the quinoline rather than the pyrazole moiety of the MP-10 pharmacophore and performed in vivo evaluation. Biodistribution studies in rats showed ~2-fold higher activity in the PDE10A-enriched striatum than nontarget brain regions; this ratio increased from 5 to 30 min postinjection, particularly for [(18)F]18a-d and [(18)F]20a. MicroPET studies of [(18)F]18d and [(18)F]20a in nonhuman primates provided clear visualization of striatum with suitable equilibrium kinetics and favorable metabolic stability. These results suggest this strategy may identify a (18)F-labeled PET tracer for quantifying the levels of PDE10A in patients with CNS disorders including Huntington's disease and schizophrenia.
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Affiliation(s)
- Junfeng Li
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Xiang Zhang
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Hongjun Jin
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Jinda Fan
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Hubert Flores
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Joel S Perlmutter
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
| | - Zhude Tu
- Department of Radiology and ‡Department of Neurology, Washington University School of Medicine , St. Louis, Missouri 63110, United States
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13
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Hwang DR, Hu E, Allen JR, Davis C, Treanor J, Miller S, Chen H, Shi B, Narayanan TK, Barret O, Alagille D, Yu Z, Slifstein M. Radiosynthesis and initial characterization of a PDE10A specific PET tracer [18F]AMG 580 in non-human primates. Nucl Med Biol 2015; 42:654-63. [PMID: 25935386 DOI: 10.1016/j.nucmedbio.2015.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 03/12/2015] [Accepted: 04/10/2015] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Phosphodiesterase 10A (PDE10A) is an intracellular enzyme responsible for the breakdown of cyclic nucleotides which are important second messengers for neurotransmission. Inhibition of PDE10A has been identified as a potential target for treatment of various neuropsychiatric disorders. To assist drug development, we have identified a selective PDE10A positron emission tomography (PET) tracer, AMG 580. We describe here the radiosynthesis of [(18)F]AMG 580 and in vitro and in vivo characterization results. METHODS The potency and selectivity were determined by in vitro assay using [(3)H]AMG 580 and baboon brain tissues. [(18)F]AMG 580 was prepared by a 1-step [(18)F]fluorination procedure. Dynamic brain PET scans were performed in non-human primates. Regions-of-interest were defined on individuals' MRIs and transferred to the co-registered PET images. Data were analyzed using two tissue compartment analysis (2TC), Logan graphical (Logan) analysis with metabolite-corrected input function and the simplified reference tissue model (SRTM) method. A PDE10A inhibitor and unlabeled AMG 580 were used to demonstrate the PDE10A specificity. KD was estimated by Scatchard analysis of high and low affinity PET scans. RESULTS AMG 580 has an in vitro KD of 71.9 pM. Autoradiography showed specific uptake in striatum. Mean activity of 121 ± 18 MBq was used in PET studies. In Rhesus, the baseline BPND for putamen and caudate was 3.38 and 2.34, respectively, via 2TC, and 3.16, 2.34 via Logan, and 2.92, and 2.01 via SRTM. A dose dependent decrease of BPND was observed by the pre-treatment with a PDE10A inhibitor. In baboons, 0.24 mg/kg dose of AMG 580 resulted in about 70% decrease of BPND. The in vivo KD of [(18)F]AMG 580 was estimated to be around 0.44 nM in baboons. CONCLUSION [(18)F]AMG 580 is a selective and potent PDE10A PET tracer with excellent specific striatal binding in non-human primates. It warrants further evaluation in humans.
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Affiliation(s)
- Dah-Ren Hwang
- Medical Sciences, 271 Running Water Ct, Ambler, PA 19002.
| | - Essa Hu
- Small Molecule Chemistry, Amgen Inc., Thousand Oaks, CA, USA
| | | | - Carl Davis
- Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, CA, USA
| | | | - Silke Miller
- Neuroscience, Amgen Inc., Thousand Oaks, CA, USA
| | - Hang Chen
- Neuroscience, Amgen Inc., South San Francisco, USA
| | - Bingzhi Shi
- Department of Nuclear Medicine, Kettering Medical Center, Kettering, OH, USA
| | | | | | | | - Zhigang Yu
- Medical Sciences, 271 Running Water Ct, Ambler, PA 19002.
| | - Mark Slifstein
- Department of Psychiatry, Columbia University, New York, NY, USA; New York State Psychiatric Institute, NY, USA
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