1
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Xue L, Jie CVML, Desrayaud S, Auberson YP. Developing Low Molecular Weight PET and SPECT Imaging Agents. ChemMedChem 2024:e202400094. [PMID: 38634545 DOI: 10.1002/cmdc.202400094] [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: 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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2
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Akbari B, Huber BR, Sherman JH. Unlocking the Hidden Depths: Multi-Modal Integration of Imaging Mass Spectrometry-Based and Molecular Imaging Techniques. Crit Rev Anal Chem 2023:1-30. [PMID: 37847593 DOI: 10.1080/10408347.2023.2266838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
Multimodal imaging (MMI) has emerged as a powerful tool in clinical research, combining different imaging modes to acquire comprehensive information and enabling scientists and surgeons to study tissue identification, localization, metabolic activity, and molecular discovery, thus aiding in disease progression analysis. While multimodal instruments are gaining popularity, challenges such as non-standardized characteristics, custom software, inadequate commercial support, and integration issues with other instruments need to be addressed. The field of multimodal imaging or multiplexed imaging allows for simultaneous signal reproduction from multiple imaging strategies. Intraoperatively, MMI can be integrated into frameless stereotactic surgery. Recent developments in medical imaging modalities such as magnetic resonance imaging (MRI), and Positron Emission Topography (PET) have brought new perspectives to multimodal imaging, enabling early cancer detection, molecular tracking, and real-time progression monitoring. Despite the evidence supporting the role of MMI in surgical decision-making, there is a need for comprehensive studies to validate and perform integration at the intersection of multiple imaging technologies. They were integrating mass spectrometry-based technologies (e.g., imaging mass spectrometry (IMS), imaging mass cytometry (IMC), and Ion mobility mass spectrometry ((IM-IM) with medical imaging modalities, offering promising avenues for molecular discovery and clinical applications. This review emphasizes the potential of multi-omics approaches in tissue mapping using MMI integrated into desorption electrospray ionization (DESI) and matrix-assisted laser desorption ionization (MALDI), allowing for sequential analyses of the same section. By addressing existing knowledge gaps, this review encourages future research endeavors toward multi-omics approaches, providing a roadmap for future research and enhancing the value of MMI in molecular pathology for diagnosis.
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Affiliation(s)
- Behnaz Akbari
- Department of Chemistry, Purdue University, West Lafayette, Indiana, USA
| | - Bertrand Russell Huber
- Chobanian and Avedisian School of Medicine, Boston University, Boston, Massachusetts, USA
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA
- US Department of Veteran Affairs, VA Boston Healthcare System, Boston, Massachusetts USA
- US Department of Veterans Affairs, National Center for PTSD, Boston, Massachusetts USA
| | - Janet Hope Sherman
- Chobanian and Avedisian School of Medicine, Boston University, Boston, Massachusetts, USA
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3
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Koike T. Development of Specific PET Tracers for Central Nervous System Drug Targets. J SYN ORG CHEM JPN 2022. [DOI: 10.5059/yukigoseikyokaishi.80.1044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Tatsuki Koike
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited
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4
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Matsuda S, Hattori Y, Matsumiya K, McQuade P, Yamashita T, Aida J, Sandiego CM, Gouasmat A, Carroll VM, Barret O, Tamagnan G, Koike T, Kimura H. Design, Synthesis, and Evaluation of [ 18F]T-914 as a Novel Positron-Emission Tomography Tracer for Lysine-Specific Demethylase 1. J Med Chem 2021; 64:12680-12690. [PMID: 34423983 DOI: 10.1021/acs.jmedchem.1c00653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Histone methylation is associated with the pathophysiology of neurodevelopmental disorders. Lysine-specific demethylase 1 (LSD1) catalyzes histone demethylation in a flavin adenine dinucleotide (FAD)-dependent manner. Thus, inhibiting LSD1 enzyme activity could offer a novel way to treat neurodevelopmental disorders. Assessing LSD1 target engagement using positron-emission tomography (PET) imaging could aid in developing therapeutic LSD1 inhibitors. In this study, PET probes based on 4-(2-aminocyclopropyl)benzamide derivatives that bind irreversibly to FAD found in LSD1 were examined. By optimizing the profiles of brain penetrance and brain-penetrant metabolites, T-914 (1g) was identified as a suitable PET tracer candidate. PET studies in nonhuman primates demonstrated that [18F]1g had heterogeneous brain uptake, which corresponded to known LSD1 expression levels. Moreover, brain uptake of [18F]1g was reduced by coadministration of unlabeled 1g, demonstrating blockable binding. These data suggest that [18F]1g warrants further investigation as a potential PET tracer candidate for assessing target engagement of LSD1.
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Affiliation(s)
- Satoru Matsuda
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yasushi Hattori
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Kouta Matsumiya
- Drug Metabolism and Pharmacokinetics Research Laboratories, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Paul McQuade
- Quantitative Translational Science - Imaging, Takeda Pharmaceutical Company Limited, 40 Landsdowne Street, Cambridge, Massachusetts 02139, United States
| | - Tohru Yamashita
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Jumpei Aida
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Christine M Sandiego
- Invicro, A Konica Minolta Company, 60 Temple Street, Suite 8A, New Haven, Connecticut 06510, United States
| | - Alexandra Gouasmat
- Invicro, A Konica Minolta Company, 60 Temple Street, Suite 8A, New Haven, Connecticut 06510, United States
| | - Vincent M Carroll
- Invicro, A Konica Minolta Company, 60 Temple Street, Suite 8A, New Haven, Connecticut 06510, United States
| | - Olivier Barret
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265 Fontenay-aux-Roses, France
| | - Gilles Tamagnan
- XingImaging LLC, 760 Temple Street, New Haven, Connecticut 06510, United States
| | - Tatsuki Koike
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Haruhide Kimura
- Neuroscience Drug Discovery Unit, Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
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5
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Hattori Y, Yamasaki T, Ohashi T, Miyanohana Y, Kusumoto T, Maeda R, Miyamoto M, Debori Y, Hata A, Zhang Y, Wakizaka H, Wakabayashi T, Fujinaga M, Yamashita R, Zhang MR, Koike T. Design, Synthesis, and Evaluation of 11C-Labeled 3-Acetyl-Indole Derivatives as a Novel Positron Emission Tomography Imaging Agent for Diacylglycerol Kinase Gamma (DGKγ) in Brain. J Med Chem 2021; 64:11990-12002. [PMID: 34347478 DOI: 10.1021/acs.jmedchem.1c00584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diacylglycerol kinase gamma (DGKγ) is a subtype of DGK enzyme, which catalyzes ATP-dependent conversion of diacylglycerol to phosphatidic acid. DGKγ, localized in the brain, plays an important role in the central nervous system. However, its function has not been widely investigated. Positron emission tomography (PET) imaging of DGKγ validates target engagement of therapeutic DGKγ inhibitors and investigates DGKγ levels under normal and disease conditions. In this study, we designed and synthesized a series of 3-acetyl indole derivatives as candidates for PET imaging agents for DGKγ. Among the synthesized compounds, 2-((3-acetyl-1-(6-methoxypyridin-3-yl)-2-methyl-1H-indol-5-yl)oxy)-N-methylacetamide (9) exhibited potent inhibitory activity (IC50 = 30 nM) against DGKγ and desirable physicochemical properties allowing efficient blood-brain barrier penetration and low levels of undesirable nonspecific binding. The radiolabeling of 9 followed by PET imaging of wild-type and DGKγ-deficient mice and rats indicated that [11C]9 ([11C]T-278) specifically binds to DGKγ and yields a high signal-to-noise ratio for DGKγ in rodent brains.
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Affiliation(s)
- Yasushi Hattori
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tomoteru Yamasaki
- Department of Advanced Nuclear Medicine Sciences, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Tomohiro Ohashi
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yuhei Miyanohana
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tomokazu Kusumoto
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Ryouta Maeda
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Maki Miyamoto
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yasuyuki Debori
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Akito Hata
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yiding Zhang
- Department of Advanced Nuclear Medicine Sciences, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Hidekatsu Wakizaka
- Department of Advanced Nuclear Medicine Sciences, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Takeshi Wakabayashi
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masayuki Fujinaga
- Department of Advanced Nuclear Medicine Sciences, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Ryo Yamashita
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Tatsuki Koike
- Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
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6
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Thentu JB, Bhyrapuneni G, Padala NP, Chunduru P, Pantangi HR, Nirogi R. Evaluation of monoamine oxidase A and B type enzyme occupancy using non-radiolabelled tracers in rat brain. Neurochem Int 2021; 145:105006. [PMID: 33636211 DOI: 10.1016/j.neuint.2021.105006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Monoamine oxidase (MAO) enzymes, type A and B metabolise the amine neurotransmitters of the body. Selective inhibition of either enzyme is an approach for treating neurodegenerative and stress-induced disorders, and inhibition of an enzyme is proportional to the binding of the MAO inhibitor. Conventionally, the binding of test compounds to enzymes is assessed by radiolabelled ligands in ex vivo and in vivo occupancy assays. Regulatory restrictions and turnaround time are the limitations of the methods that use radiolabelled ligands. But the use of non-radiolabelled tracers and sensitive mass spectrometry (LC-MS/MS) based assays accelerated the determination of target occupancy in pre-clinical species. A report on use of non-radiolabelled ligand in in vivo MAO occupancy assay is not available. The objectives of the present study were to optimise non-radiolabelled harmine and deprenyl as selective tracers in MAO-A and MAO-B occupancy assays and evaluate MAO occupancy of test compounds in rat brain. Tracer optimisation resulted in a detectable, stable, and low ratio (<3.0) of tracer concentrations between any two brain tissues. In occupancy assay, tracer was intravenously administered (10 μg/kg, harmine or 60 μg/kg, L-deprenyl) after the treatment with test compound (clorgyline or tranylcypromine or pargyline or phenelzine or thioperamide). Specific brain tissues were isolated at a defined interval and tracer concentrations were quantified using LC-MS/MS method. Pre-treatment with MAO inhibitors resulted in a decrease (maximum, 80-85%) in harmine or an increase (maximum, 85-300%) in L-deprenyl concentrations. But we considered the change in tracer concentration, relative to the vehicle and positive control groups to calculate MAO occupancy. The observed selectivity and ratio of occupancies (ED50) of test compound towards MAO-A and MAO-B are comparable with the results from in vitro radiolabelled ligand-based inhibition assay. The results demonstrated the application of these non-radiolabelled tracers as suitable pre-clinical tools to determine MAO occupancy.
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Affiliation(s)
- Jagadeesh Babu Thentu
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Gopinadh Bhyrapuneni
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Nagasurya Prakash Padala
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Prathyusha Chunduru
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Hanumanth Rao Pantangi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Ramakrishna Nirogi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
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7
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Shaw RC, Tamagnan GD, Tavares AAS. Rapidly (and Successfully) Translating Novel Brain Radiotracers From Animal Research Into Clinical Use. Front Neurosci 2020; 14:871. [PMID: 33117115 PMCID: PMC7559529 DOI: 10.3389/fnins.2020.00871] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 07/27/2020] [Indexed: 12/26/2022] Open
Abstract
The advent of preclinical research scanners for in vivo imaging of small animals has added confidence into the multi-step decision-making process of radiotracer discovery and development. Furthermore, it has expanded the utility of imaging techniques available to dissect clinical questions, fostering a cyclic interaction between the clinical and the preclinical worlds. Significant efforts from medicinal chemistry have also made available several high-affinity and selective compounds amenable for radiolabeling, that target different receptors, transporters and enzymes in vivo. This substantially increased the range of applications of molecular imaging using positron emission tomography (PET) or single photon emission computed tomography (SPECT). However, the process of developing novel radiotracers for in vivo imaging of the human brain is a multi-step process that has several inherent pitfalls and technical difficulties, which often hampers the successful translation of novel imaging agents from preclinical research into clinical use. In this paper, the process of radiotracer development and its relevance in brain research is discussed; as well as, its pitfalls, technical challenges and future promises. Examples of successful and unsuccessful translation of brain radiotracers will be presented.
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Affiliation(s)
- Robert C. Shaw
- BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Edinburgh Imaging, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Adriana Alexandre S. Tavares
- BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Edinburgh Imaging, University of Edinburgh, Edinburgh, United Kingdom
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8
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Gobbi L, Mercier J, Bang-Andersen B, Nicolas JM, Reilly J, Wagner B, Whitehead D, Briard E, Maguire RP, Borroni E, Auberson YP. A Comparative Study of in vitro Assays for Predicting the Nonspecific Binding of PET Imaging Agents in vivo. ChemMedChem 2019; 15:585-592. [PMID: 31797561 DOI: 10.1002/cmdc.201900608] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/27/2019] [Indexed: 01/23/2023]
Abstract
Nonspecific binding (NSB) is a key parameter in optimizing PET imaging tracers. We compared the ability to predict NSB of three available methods: LIMBA, rat fu,brain , and CHI(IAM). Even though NSB is often associated with lipophilicity, we observed that logD does not correlate with any of these assays, clearly indicating that lipophilicity, while influencing NSB, is insufficient to predict it. A cross-comparison of the methods showed that all three correlate and are useful predictors of NSB. The three assays, however, rank the molecules slightly differently, illustrating the challenge of comparing molecules within a narrow chemical space. We also noted that CHI(IAM) values more effectively predict VNS , a measure of in vivo NSB in the human brain. CHI(IAM) measurements might be a closer model of the actual physicochemical interaction between PET tracer candidates and cell membranes, and seems to be the method of choice for the optimization of in vivo NSB.
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Affiliation(s)
- Luca Gobbi
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - Joël Mercier
- UCB Early Solutions, UCB Biopharma sprl, 1420, Braine-l'Alleud, Belgium
| | - Benny Bang-Andersen
- Molecular Discovery and Innovation, H. Lundbeck A/S, 9 Ottiliavej, 2500, Valby, Denmark
| | | | - John Reilly
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - Björn Wagner
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - David Whitehead
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - Emmanuelle Briard
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - R Paul Maguire
- UCB Early Solutions, UCB Biopharma sprl, 1420, Braine-l'Alleud, Belgium
| | - Edilio Borroni
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - Yves P Auberson
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
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9
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Sun M, Xiao H, Hong H, Zhang A, Zhang Y, Liu Y, Zhu L, Kung HF, Qiao J. Rapid screening of nine unradiolabeled candidate compounds as PET brain imaging agents using cassette-wave microdosing and LC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1121:28-38. [PMID: 31100605 DOI: 10.1016/j.jchromb.2019.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/03/2019] [Accepted: 05/05/2019] [Indexed: 11/17/2022]
Abstract
The R&D of PET imaging agents is a complex system engineering, simplifying screening steps and increasing screening efficiency have become popular issues. The purpose of this study is to develop a new screening procedure using cassette-wave microdosing and LC-MS/MS to enhance the screening throughput of unradiolabeled candidate compounds as PET imaging agents. Nine compounds were divided into 3 sets and made into 3 cassettes. Fifteen rats were randomly divided into 3 groups, and every animal received three intravenous bolus injections at three different time points; the doses were at microdose levels. This dosing approach takes advantage of temporal and spatial differences and is likened to an input wave; therefore, this approach was named cassette-wave microdosing. The samples of different brain regions such as the hypothalamus, striatum, hippocampus, cortex, cerebellum and the remainder of the brain were detected by LC-MS/MS analysis. The research potential of the compounds as PET imaging agents is evaluated in terms of brain biodistribution data. The screening method is rapid, highly efficient, reliable and reduces animal usage. Additionally, it can shorten the evaluation process of radiopharmaceuticals and enhance the screening throughput of PET radiopharmaceuticals without the use of radioactive agents.
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Affiliation(s)
- Mingyue Sun
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Hao Xiao
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
| | - Haiyan Hong
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Aili Zhang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Yan Zhang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Yajing Liu
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
| | - Lin Zhu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China; Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
| | - Hank F Kung
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.
| | - Jinping Qiao
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China.
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10
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Hattori Y, Aoyama K, Maeda J, Arimura N, Takahashi Y, Sasaki M, Fujinaga M, Seki C, Nagai Y, Kawamura K, Yamasaki T, Zhang MR, Higuchi M, Koike T. Design, Synthesis, and Evaluation of (4R)-1-{3-[2-(18F)Fluoro-4-methylpyridin-3-yl]phenyl}-4-[4-(1,3-thiazol-2-ylcarbonyl)piperazin-1-yl]pyrrolidin-2-one ([18F]T-401) as a Novel Positron-Emission Tomography Imaging Agent for Monoacylglycerol Lipase. J Med Chem 2019; 62:2362-2375. [DOI: 10.1021/acs.jmedchem.8b01576] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yasushi Hattori
- Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Kazunobu Aoyama
- Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Jun Maeda
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Naoto Arimura
- Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yasuko Takahashi
- Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masako Sasaki
- Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masayuki Fujinaga
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Chie Seki
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Yuji Nagai
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Kazunori Kawamura
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Tomoteru Yamasaki
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Ming-Rong Zhang
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Makoto Higuchi
- National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
| | - Tatsuki Koike
- Research, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi, 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
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11
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Xu Y, Li Z. Imaging metabotropic glutamate receptor system: Application of positron emission tomography technology in drug development. Med Res Rev 2019; 39:1892-1922. [DOI: 10.1002/med.21566] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Youwen Xu
- Independent Consultant and Contractor, Radiopharmaceutical Development, Validation and Bio-Application; Philadelphia Pennsylvania
| | - Zizhong Li
- Pharmaceutical Research and Development, SOFIE Biosciences; Somerset New Jersey
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Nabulsi NB, Holden D, Zheng MQ, Bois F, Lin SF, Najafzadeh S, Gao H, Ropchan J, Lara-Jaime T, Labaree D, Shirali A, Slieker L, Jesudason C, Barth V, Navarro A, Kant N, Carson RE, Huang Y. Evaluation of 11C-LSN3172176 as a Novel PET Tracer for Imaging M 1 Muscarinic Acetylcholine Receptors in Nonhuman Primates. J Nucl Med 2019; 60:1147-1153. [PMID: 30733324 DOI: 10.2967/jnumed.118.222034] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/29/2018] [Indexed: 11/16/2022] Open
Abstract
The M1 muscarinic acetylcholine receptor (mAChR) plays an important role in learning and memory, and therefore is a target for development of drugs for treatment of cognitive impairments in Alzheimer disease and schizophrenia. The availability of M1-selective radiotracers for PET will help in developing therapeutic agents by providing an imaging tool for assessment of drug dose-receptor occupancy relationship. Here we report the synthesis and evaluation of 11C-LSN3172176 (ethyl 4-(6-(methyl-11 C)-2-oxoindolin-1-yl)-[1,4'-bipiperidine]-1'-carboxylate) in nonhuman primates. Methods: 11C-LSN3172176 was radiolabeled via the Suzuki-Miyaura cross-coupling method. PET scans in rhesus macaques were acquired for 2 h with arterial blood sampling and metabolite analysis to measure the input function. Blocking scans with scopolamine (50 μg/kg) and the M1-selective agent AZD6088 (0.67 and 2 mg/kg) were obtained to assess tracer binding specificity and selectivity. Regional brain time-activity curves were analyzed with the 1-tissue-compartment model and the multilinear analysis method (MA1) to calculate regional distribution volume. Nondisplaceable binding potential values were calculated using the cerebellum as a reference region. Results: 11C-LSN3172176 was synthesized with greater than 99% radiochemical purity and high molar activity. In rhesus monkeys, 11C-LSN3172176 metabolized rapidly (29% ± 6% parent remaining at 15 min) and displayed fast kinetics and extremely high uptake in the brain. Imaging data were modeled well with the 1-tissue-compartment model and MA1 methods. MA1-derived distribution volume values were high (range, 10-81 mL/cm3) in all known M1 mAChR-rich brain regions. Pretreatment with scopolamine and AZD6088 significantly reduced the brain uptake of 11C-LSN3172176, thus demonstrating its binding specificity and selectivity in vivo. The cerebellum appeared to be a suitable reference region for derivation of nondisplaceable binding potential, which ranged from 2.42 in the globus pallidus to 8.48 in the nucleus accumbens. Conclusion: 11C-LSN3172176 exhibits excellent in vivo binding and imaging characteristics in nonhuman primates and appears to be the first appropriate radiotracer for PET imaging of human M1 AChR.
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Affiliation(s)
- Nabeel B Nabulsi
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Daniel Holden
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Ming-Qiang Zheng
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Frederic Bois
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Shu-Fei Lin
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Soheila Najafzadeh
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Hong Gao
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Jim Ropchan
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Teresa Lara-Jaime
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - David Labaree
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Anupama Shirali
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | | | | | | | | | - Nancy Kant
- Eli Lilly and Co., Indianapolis, Indiana
| | - Richard E Carson
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; and
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Influence of incubation conditions on microsomal metabolism of xanthine-derived A 1 adenosine receptor ligands. J Pharmacol Toxicol Methods 2018; 95:16-26. [PMID: 30476620 DOI: 10.1016/j.vascn.2018.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/03/2018] [Accepted: 11/21/2018] [Indexed: 11/23/2022]
Abstract
INTRODUCTION In vitro metabolism models such as liver microsomes represent an important tool for the development of novel radioligands. Comparability and physiological relevance of in vitro metabolism data critically depend on the careful evaluation and optimization of assay protocols. We therefore investigated the influence of incubation conditions on the microsomal stability of xanthine-derived A1 adenosine receptor (A1AR) ligands which have been developed for positron emission tomography (PET). METHODS Substrate depletion assays using rat liver microsomes (RLM) were performed for three analogous compounds which differ with regard to the metabolically vulnerable substituent at the xanthine C8 position. Incubation conditions were varied systematically. Additionally, the stability of the cofactor NADPH during incubation was investigated. RESULTS Microsomal metabolism was strongly influenced by buffer pH, organic solvents and preincubation time. Substrate depletion values varied up to 5-fold depending on incubation matrix composition, however, the rank order of metabolic stability remained unchanged. Prolonged incubation periods led to drastic loss in enzyme activity which could not be prevented by addition of metal chelators or antioxidants. Cofactor NADPH was rapidly oxidized in microsomal matrix, even in the absence of cytochrome P450 substrates. DISCUSSION In summary, short incubation times, precise pH control and minimal concentrations of organic solvents are mandatory to obtain reliable microsomal stability data. Furthermore, in vitro metabolic stability of the tested A1AR ligands varied largely depending on the particular C8 substituent. Consequently, structural modifications at the xanthine C8 position appear to be a promising strategy for the improvement of A1AR PET radioligands.
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Collier TL, Dahl K, Stephenson NA, Holland JP, Riley A, Liang SH, Vasdev N. Recent applications of a single quadrupole mass spectrometer in 11C, 18F and radiometal chemistry. J Fluor Chem 2018; 210:46-55. [PMID: 30410189 PMCID: PMC6217822 DOI: 10.1016/j.jfluchem.2018.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mass spectrometry (MS) has longstanding applications in radiochemistry laboratories, stemming from carbon-dating. However, research on the development of radiotracers for molecular imaging with either positron emission tomography (PET) or single photon emission computed tomography has yet to take full advantage of MS. This inertia has been attributed to the relatively low concentrations of radiopharmaceutical formulations and lack of access to the required MS equipment due to the high costs for purchase and maintenance of specialized MS systems. To date, single quadrupole (SQ)-MS coupled to liquid chromatography (LC) systems is the main form of MS that has been used in radiochemistry laboratories. These LC/MS systems are primarily used for assessing the chemical purity of radiolabeling precursor or standard molecules but also have applications in the determination of metabolites. Herein, we highlight personal experiences using a compact SQ-MS in our PET radiochemistry laboratories, to monitor the small amounts of carrier observed in most radiotracer preparations, even at high molar activities. The use of a SQ-MS in the observation of the low mass associated with non-radioactive species which are formed along with the radiotracer from the trace amounts of carrier found is demonstrated. Herein, we describe a pre-concentration system to detect dilute radiopharmaceutical formulations and metabolite analyses by SQ-MS. Selected examples where SQ-MS was critical for optimization of radiochemical reactions and for unequivocal characterization of radiotracers are showcased. We also illustrate examples where SQ-MS can be applied in identification of radiometal complexes and development of a new purification methodology for Pd-catalyzed radiofluorination reactions, shedding light on the identity of metal complexes present in the labelling solution.
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Affiliation(s)
- Thomas L. Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
- Advion, Inc., Ithaca, New York, USA
| | - Kenneth Dahl
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Nickeisha A. Stephenson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jason P. Holland
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Adam Riley
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital (MGH) & Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
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Developing a cassette microdosing approach to enhance the throughput of PET imaging agent screening. J Pharm Biomed Anal 2018. [PMID: 29533858 DOI: 10.1016/j.jpba.2018.02.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cassette dosing is also known as N-in-One dosing: several compounds are simultaneously administrated to a single animal and then the samples are rapidly detected by LC-MS/MS. This approach is a successful strategy to enhance the efficiency of drug discovery and reduce animal usage. However, no report on the utility of the cassette approach in radiotracer discovery has appeared in the literature. This study designed a cassette microdose with LC-MS/MS method to enhance the throughput for screening radiopharmaceutical biodistribution in the rat brain directly. Three unradiolabeled compounds (FPBM FPBM2 and AV-133) were chosen as model drugs administrated intravenously to the rats as a cassette as opposed to discrete study. The rat brain biodistribution data, target localization, the differential uptake ratio (%ID/g) and the brain tissue-specific binding ratio were obtained by the LC-MS/MS analysis. These data matched very well with the values obtained by the standard radioactivity measurements. Moreover, no significant differences between discrete dosing and cassette dosing were observed. By circumventing the need for radiolabeled molecules, this method may be high-throughput and safe for the research and development of new PET imaging agents. The combination of cassette microdosing and LC-MS/MS would be a medium throughput screening tool at an early stage in the discovery/development process of PET imaging agents.
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Andrés JI, Schmidt M. Medicinal Chemistry strategies for PET tracer discovery. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017; 25:11-17. [PMID: 29233262 DOI: 10.1016/j.ddtec.2017.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/29/2017] [Accepted: 10/10/2017] [Indexed: 06/07/2023]
Abstract
The detection of gamma rays, resulting from decay of positron emitting isotopes, allows exquisitely sensitive detection of probes radiolabeled with such isotopes. These probes can be designed for high affinity binding to specific molecular targets and be used as tools in the early development of drugs, particularly for neuropsychiatric disorders. Availability of novel tracers requires dedicated resources and selection assays. Many of the selection assays are similar to those used for discovery of clinical compounds, although the distribution and clearance of target specific radioligands requires different in vitro and in vivo methods and new derivatives.
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Affiliation(s)
- José Ignacio Andrés
- Discovery Sciences, Janssen Research & Development, Janssen-Cilag S. A., C/Jarama 75A, 45007 Toledo, Spain.
| | - Mark Schmidt
- Neuroscience Therapeutic Area, Janssen Research & Development, Division of Janssen Pharmaceutica, NV, Turnhoutseweg 30, Beerse 2340, Belgium
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Approaches for the discovery of novel positron emission tomography radiotracers for brain imaging. Clin Transl Imaging 2017. [DOI: 10.1007/s40336-017-0221-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Target Engagement Measures in Preclinical Drug Discovery: Theory, Methods, and Case Studies. TRANSLATING MOLECULES INTO MEDICINES 2017. [DOI: 10.1007/978-3-319-50042-3_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Wu X, Zhou X, Zhang S, Zhang Y, Deng A, Han J, Zhu L, Kung HF, Qiao J. Brain uptake of a non-radioactive pseudo-carrier and its effect on the biodistribution of [(18)F]AV-133 in mouse brain. Nucl Med Biol 2015; 42:630-6. [PMID: 25910857 DOI: 10.1016/j.nucmedbio.2015.03.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 03/28/2015] [Accepted: 03/30/2015] [Indexed: 10/23/2022]
Abstract
INTRODUCTION 9-[(18)F]Fluoropropyl-(+)-dihydrotetrabenazine ([(18)F]AV-133) is a new PET imaging agent targeting vesicular monoamine transporter type II (VMAT2). To shorten the preparation of [(18)F]AV-133 and to make it more widely available, a simple and rapid purification method using solid-phase extraction (SPE) instead of high-pressure liquid chromatography (HPLC) was developed. The SPE method produced doses containing the non-radioactive pseudo-carrier 9-hydroxypropyl-(+)-dihydrotetrabenazine (AV-149). The objectives of this study were to evaluate the brain uptake of AV-149 by UPLC-MS/MS and its effect on the biodistribution of [(18)F]AV-133 in the brains of mice. METHODS The mice were injected with a bolus including [(18)F]AV-133 and different doses of AV-149. Brain tissue and blood samples were harvested. The effect of different amounts of AV-149 on [(18)F]AV-133 was evaluated by quantifying the brain distribution of radiolabelled tracer [(18)F]AV-133. The concentrations of AV-149 in the brain and plasma were analyzed using a UPLC-MS/MS method. RESULTS The concentrations of AV-149 in the brain and plasma exhibited a good linear relationship with the doses. The receptor occupancy curve was fit, and the calculated ED50 value was 8.165mg/kg. The brain biodistribution and regional selectivity of [(18)F]AV-133 had no obvious differences at AV-149 doses lower than 0.1mg/kg. With increasing doses of AV-149, the brain biodistribution of [(18)F]AV-133 changed significantly. CONCLUSION The results are important to further support that the improved radiolabelling procedure of [(18)F]AV-133 using an SPE method may be suitable for routine clinical application.
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Affiliation(s)
- Xianying Wu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Xue Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Shuxian Zhang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Yan Zhang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Aifang Deng
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Jie Han
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Lin Zhu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China; Center of Parkinson's Disease, Beijing Institute for Brain Disorders, Beijing, China.
| | - Hank F Kung
- Center of Parkinson's Disease, Beijing Institute for Brain Disorders, Beijing, China
| | - Jinping Qiao
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China.
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Durham TB, Blanco MJ. Target Engagement in Lead Generation. Bioorg Med Chem Lett 2015; 25:998-1008. [DOI: 10.1016/j.bmcl.2014.12.076] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/15/2014] [Accepted: 12/23/2014] [Indexed: 12/15/2022]
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Joshi EM, Need A, Schaus J, Chen Z, Benesh D, Mitch C, Morton S, Raub TJ, Phebus L, Barth V. Efficiency gains in tracer identification for nuclear imaging: can in vivo LC-MS/MS evaluation of small molecules screen for successful PET tracers? ACS Chem Neurosci 2014; 5:1154-63. [PMID: 25247893 DOI: 10.1021/cn500073j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Positron emission tomography (PET) imaging has become a useful noninvasive technique to explore molecular biology within living systems; however, the utility of this method is limited by the availability of suitable radiotracers to probe specific targets and disease biology. Methods to identify potential areas of improvement in the ability to predict small molecule performance as tracers prior to radiolabeling would speed the discovery of novel tracers. In this retrospective analysis, we characterized the brain penetration or peak SUV (standardized uptake value), binding potential (BP), and brain exposure kinetics across a series of known, nonradiolabeled PET ligands using in vivo LC-MS/MS (liquid chromatography coupled to mass spectrometry) and correlated these parameters with the reported PET ligand performance in nonhuman primates and humans available in the literature. The PET tracers studied included those reported to label G protein-coupled receptors (GPCRs), intracellular enzymes, and transporters. Additionally, data for each tracer was obtained from a mouse brain uptake assay (MBUA), previously published, where blood-brain barrier (BBB) penetration and clearance parameters were assessed and compared against similar data collected on a broad compound set of central nervous system (CNS) therapeutic compounds. The BP and SUV identified via nonradiolabeled LC-MS/MS, while different from the published values observed in the literature PET tracer data, allowed for an identification of initial criteria values we sought to facilitate increased potential for success from our early discovery screening paradigm. Our analysis showed that successful, as well as novel, clinical PET tracers exhibited BP of greater than 1.5 and peak SUVs greater than approximately 150% at 5 min post dose in rodents. The brain kinetics appeared similar between both techniques despite differences in tracer dose, suggesting linearity across these dose ranges. The assessment of tracers in a CNS exposure model, the mouse brain uptake assessment (MBUA), showed that those compound with initial brain-to-plasma ratios >2 and unbound fraction in brain homogenate >0.01 were more likely to be clinically successful PET ligands. Taken together, early incorporation of a LC/MS/MS cold tracer discovery assay and a parallel MBUA can be an useful screening paradigm to prioritize and rank order potential novel PET radioligands during early tracer discovery efforts. Compounds considered for continued in vivo PET assessments can be identified quickly by leveraging in vitro affinity and selectivity measures, coupled with data from a MBUA, primarily the 5 min brain-to-plasma ratio and unbound fraction data. Coupled utilization of these data creates a strategy to efficiently screen for the identification of appropriate chemical space to invest in for radiotracer discovery.
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Affiliation(s)
- Elizabeth M. Joshi
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Anne Need
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - John Schaus
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Zhaogen Chen
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Dana Benesh
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Charles Mitch
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Stuart Morton
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Thomas J. Raub
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Lee Phebus
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
| | - Vanessa Barth
- Eli Lilly and Co., Lilly Research Laboratories, Indianapolis, Indiana 46285, United States
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Abstract
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Decades after its discovery, positron emission tomography (PET)
remains the premier tool for imaging neurochemistry in living humans.
Technological improvements in radiolabeling methods, camera design,
and image analysis have kept PET in the forefront. In addition, the
use of PET imaging has expanded because researchers have developed
new radiotracers that visualize receptors, transporters, enzymes,
and other molecular targets within the human brain. However,
of the thousands of proteins in the central nervous system
(CNS), researchers have successfully imaged fewer than 40 human proteins.
To address the critical need for new radiotracers, this Account expounds
on the decisions, strategies, and pitfalls of CNS radiotracer development
based on our current experience in this area. We discuss the
five key components of radiotracer development for
human imaging: choosing a biomedical question, selection of a biological
target, design of the radiotracer chemical structure, evaluation of
candidate radiotracers, and analysis of preclinical imaging. It is
particularly important to analyze the market of scientists or companies
who might use a new radiotracer and carefully select a relevant biomedical
question(s) for that audience. In the selection of a specific biological
target, we emphasize how target localization and identity can constrain
this process and discuss the optimal target density and affinity ratios
needed for binding-based radiotracers. In addition, we discuss various
PET test–retest variability requirements for monitoring changes
in density, occupancy, or functionality for new radiotracers. In the synthesis of new radiotracer structures, high-throughput,
modular syntheses have proved valuable, and these processes provide
compounds with sites for late-stage radioisotope installation. As
a result, researchers can manage the time constraints associated with
the limited half-lives of isotopes. In order to evaluate brain uptake,
a number of methods are available to predict bioavailability, blood–brain
barrier (BBB) permeability, and the associated issues of nonspecific
binding and metabolic stability. To evaluate the synthesized chemical
library, researchers need to consider high-throughput affinity assays,
the analysis of specific binding, and the importance of fast binding
kinetics. Finally, we describe how we initially assess preclinical
radiotracer imaging, using brain uptake, specific binding, and preliminary
kinetic analysis to identify promising radiotracers that may be useful
for human brain imaging. Although we discuss these five design components
separately and linearly in this Account, in practice we develop new
PET-based radiotracers using these design components nonlinearly and
iteratively to develop new compounds in the most efficient way possible.
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Affiliation(s)
- Genevieve C. Van de Bittner
- Athinoula
A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Emily L. Ricq
- Athinoula
A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, United States
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Jacob M. Hooker
- Athinoula
A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, United States
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