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Ridler K, Rizzo G, Burstein ES, Forsberg Morén A, Stepanov V, Halldin C, Rabiner EA. Imaging the 5-HT 2C receptor with PET: Evaluation of 5-HT 2C and 5-HT 2A affinity of pimavanserin in the primate brain. J Cereb Blood Flow Metab 2024:271678X241276312. [PMID: 39169749 DOI: 10.1177/0271678x241276312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Two complimentary techniques were used to estimate occupancy of pimavanserin (a selective 5-HT2A/2C inverse agonist) to 5-HT2A and 5-HT2C receptors in non-human primate brains. One employed the 5-HT2A/2C selective radioligand [11C]CIMBI-36 combined with quantification of binding potentials in brain regions known to be enriched in 5-HT2A (cortex) or 5-HT2C (choroid plexus) receptors to estimate occupancy. Pimavanserin was 6-10 fold more potent displacing [11C]CIMBI-36 from cortex (ED50 = 0.007 mg/kg; EC50 = 0.6 ng/ml) than from choroid plexus (ED50 =0.046 mg/kg; EC50 = 6.0 ng/ml). The assignment of [11C]CIMBI-36 binding to 5-HT2A and 5-HT2C receptors by anatomical brain structure was confirmed using the 5-HT2A selective inverse agonist MDL 100,907 and the 5-HT2C selective antagonist SB 242584 to displace [11C]CIMBI-36. The second technique employed a novel, 5-HT2C selective tracer called [11C]AC1332. [11C]AC1332 bound robustly to choroid plexus, moderately to hippocampus, and minimally to cortex. Pimavanserin displaced [11C]AC1332 with similar potency (ED50 = 0.062 mg/kg; EC50 = 2.5 ng/ml) as its potency displacing [11C]CIMBI-36 binding from choroid plexus. These results demonstrate the feasibility of simultaneously estimating drug occupancy of 5-HT2A and 5-HT2C receptors in vivo, and the utility of a novel 5-HT2C receptor selective tracer ligand.
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Affiliation(s)
| | - Gaia Rizzo
- Invicro, London, UK
- Division of Brain Sciences, Imperial College London, London, UK
| | | | - Anton Forsberg Morén
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
| | - Vladimir Stepanov
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
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2
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Schou M, Amini N, Takano A, Arakawa R, Dahl K, Toth M, Svedberg M, Varrone A, Halldin C. Microsome Mediated in Vitro Metabolism: A Convenient Method for the Preparation of the PET Radioligand Metabolite [ 18F]FE-PE2I-OH for Translational Dopamine Transporter Imaging. ACS Chem Neurosci 2023; 14:3732-3736. [PMID: 37753876 PMCID: PMC10587862 DOI: 10.1021/acschemneuro.3c00458] [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: 07/07/2023] [Accepted: 08/29/2023] [Indexed: 09/28/2023] Open
Abstract
Undesired radiometabolites can be detrimental to the development of positron emission tomography (PET) radioligands. Methods for quantifying radioligand metabolites in brain tissue include ex vivo studies in small animals or labeling and imaging of the radiometabolite(s) of interest. The latter is a time- and resource-demanding process, which often includes multistep organic synthesis. We hypothesized that this process could be replaced by making use of liver microsomes, an in vitro system that mimics metabolism. In this study, rat liver microsomes were used to prepare radiometabolites of the dopamine transporter radioligand [18F]FE-PE2I for in vitro imaging using autoradiography and in vivo imaging using PET in rats and nonhuman primates. The primary investigated hydroxy-metabolite [18F]FE-PE2I-OH ([18F]2) was obtained in a 2% radiochemical yield and >99% radiochemical purity. In vitro and in vivo imaging demonstrated that [18F]2 readily crossed the blood-brain barrier and bound specifically and reversibly to the dopamine transporter. In conclusions, the current study demonstrates the potential of liver microsomes in the production of radiometabolites for translational imaging studies and radioligand discovery.
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Affiliation(s)
- Magnus Schou
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
- PET
Science Centre, Precision Medicine and Biosamples, Oncology R&D, AstraZeneca, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Nahid Amini
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Akihiro Takano
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Ryosuke Arakawa
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Kenneth Dahl
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
- PET
Science Centre, Precision Medicine and Biosamples, Oncology R&D, AstraZeneca, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Miklos Toth
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Marie Svedberg
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Andrea Varrone
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Christer Halldin
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
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3
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Varnäs K, Nag S, Halldin C, Farde L. PET Evaluation of the Novel F-18 Labeled Reversible Radioligand [ 18F]GEH200449 for Detection of Monoamine Oxidase-B in the Non-Human Primate Brain. ACS Chem Neurosci 2023; 14:3206-3211. [PMID: 37587571 PMCID: PMC10485887 DOI: 10.1021/acschemneuro.3c00332] [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: 05/15/2023] [Accepted: 08/07/2023] [Indexed: 08/18/2023] Open
Abstract
Positron emission tomography (PET) using radioligands for the enzyme monoamine oxidase B (MAO-B) is increasingly applied as a marker for astrogliosis in neurodegenerative disorders. In the present study, a novel reversible fluorine-18 labeled MAO-B compound, [18F]GEH200449, was evaluated as a PET radioligand in non-human primates. PET studies of [18F]GEH200449 at baseline showed brain exposure (maximum concentration: 3.4-5.2 SUV; n = 5) within the range of that for suitable central nervous system radioligands and a regional distribution consistent with the known localization of MAO-B. Based on the quantitative assessment of [18F]GEH200449 data using the metabolite-corrected arterial plasma concentration as input function, the Logan graphical analysis was selected as the preferred method of quantification. The binding of [18F]GEH200449, as calculated based on regional estimates of the total distribution volume, was markedly inhibited (occupancy >80%) by the administration of the selective MAO-B ligands L-deprenyl (0.5 and 1.0 mg/kg) or rasagiline (0.75 mg/kg) prior to radioligand injection. Radioligand binding was displaceable by the administration of L-deprenyl (0.5 mg/kg) at 25 min after radioligand injection, thus supporting reversible binding to MAO-B. These observations support that [18F]GEH200449 is a reversible MAO-B radioligand suitable for applied studies in humans.
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Affiliation(s)
- Katarina Varnäs
- Karolinska Institutet,
Department
of Clinical Neuroscience, Center for Psychiatry Research and Stockholm
County Council, BioClinicum J:15, Visionsgatan 4, SE-171
64 Solna, Sweden
| | - Sangram Nag
- Karolinska Institutet,
Department
of Clinical Neuroscience, Center for Psychiatry Research and Stockholm
County Council, BioClinicum J:15, Visionsgatan 4, SE-171
64 Solna, Sweden
| | - Christer Halldin
- Karolinska Institutet,
Department
of Clinical Neuroscience, Center for Psychiatry Research and Stockholm
County Council, BioClinicum J:15, Visionsgatan 4, SE-171
64 Solna, Sweden
| | - Lars Farde
- Karolinska Institutet,
Department
of Clinical Neuroscience, Center for Psychiatry Research and Stockholm
County Council, BioClinicum J:15, Visionsgatan 4, SE-171
64 Solna, Sweden
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4
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Nag S, Bolin M, Datta P, Arakawa R, Forsberg Morén A, Khani Maynaq Y, Lin E, Genung N, Hering H, Guckian K, Martarello L, Kaliszczak M, Halldin C. Development of a Novel [ 11C]CO-Labeled Positron Emission Tomography Radioligand [ 11C]BIO-1819578 for the Detection of O-GlcNAcase Enzyme Activity. ACS Chem Neurosci 2023. [PMID: 37377046 PMCID: PMC10360070 DOI: 10.1021/acschemneuro.3c00247] [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: 06/29/2023] Open
Abstract
Imaging O-GlcNAcase OGA by positron emission tomography (PET) could provide information on the pathophysiological pathway of neurodegenerative diseases and important information on drug-target engagement and be helpful in dose selection of therapeutic drugs. Our aim was to develop an efficient synthetic method for labeling BIO-1819578 with carbon-11 using 11CO for evaluation of its potential to measure levels of OGA enzyme in non-human primate (NHP) brain using PET. Radiolabeling was achieved in one-pot via a carbon-11 carbonylation reaction using [11C]CO. The detailed regional brain distribution of [11C]BIO-1819578 binding was evaluated using PET measurements in NHPs. Brain radioactivity was measured for 93 min using a high-resolution PET system, and radiometabolites were measured in monkey plasma using gradient radio HPLC. Radiolabeling of [11C]BIO-1819578 was successfully accomplished, and the product was found to be stable at 1 h after formulation. [11C]BIO-1819578 was characterized in the cynomolgus monkey brain where a high brain uptake was found (7 SUV at 4 min). A pronounced pretreatment effect was found, indicating specific binding to OGA enzyme. Radiolabeling of [11C]BIO-1819578 with [11C]CO was successfully accomplished. [11C]BIO-1819578 binds specifically to OGA enzyme. The results suggest that [11C]BIO-1819578 is a potential radioligand for imaging and for measuring target engagement of OGA in the human brain.
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Affiliation(s)
- Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Martin Bolin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Prodip Datta
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Anton Forsberg Morén
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Yasir Khani Maynaq
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Edward Lin
- BIOGEN MA Inc., 225 Binney St., Cambridge, Massachusetts 02142, United States
| | - Nathan Genung
- BIOGEN MA Inc., 225 Binney St., Cambridge, Massachusetts 02142, United States
| | - Heike Hering
- BIOGEN MA Inc., 225 Binney St., Cambridge, Massachusetts 02142, United States
| | - Kevin Guckian
- BIOGEN MA Inc., 225 Binney St., Cambridge, Massachusetts 02142, United States
| | - Laurent Martarello
- BIOGEN MA Inc., 225 Binney St., Cambridge, Massachusetts 02142, United States
| | - Maciej Kaliszczak
- BIOGEN MA Inc., 225 Binney St., Cambridge, Massachusetts 02142, United States
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
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5
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Nag S, Arakawa R, Jia Z, Lachapelle E, Zhang L, Maresca K, Chen L, Jahan M, Mccarthy T, Halldin C. Characterization of a Novel M4 PAM PET Radioligand [11C]PF06885190 in Nonhuman Primates (NHP). Molecules 2023; 28:4612. [PMID: 37375167 DOI: 10.3390/molecules28124612] [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: 05/03/2023] [Revised: 06/01/2023] [Accepted: 06/01/2023] [Indexed: 06/29/2023] Open
Abstract
Muscarinic acetylcholine receptors (mAChR), including M4, draw attention as therapeutic targets for several neurodegenerative diseases including Alzheimer's disease (AD). PET imaging of M4 positive allosteric modulator (PAM) allows qualification of the distribution as well as the expression of this receptor under physiological conditions and thereby helps to assess the receptor occupancy (RO) of a drug candidate. In this study, our aims were (a) to synthesize a novel M4 PAM PET radioligand [11C]PF06885190 (b) to evaluate the brain distribution of [11C]PF06885190 in nonhuman primates (NHP) and (c) to analyze its radiometabolites in the blood plasma of NHP. Radiolabeling of [11C]PF06885190 was accomplished via N-methylation of the precursor. Six PET measurements were performed using two male cynomolgus monkeys, where three PET measurements were at baseline, two after pretreatment with a selective M4 PAM compound CVL-231 and one after pretreatment with donepezil. The total volume of distribution (VT) of [11C]PF06885190 was examined using Logan graphical analysis with arterial input function. Radiometabolites were analyzed in monkey blood plasma using gradient HPLC system. Radiolabeling of [11C]PF06885190 was successfully accomplished and the radioligand was found to be stable in the formulation, with radiochemical purity exceeding 99% 1 h after the end of the synthesis. [11C]PF06885190 was characterized in the cynomolgus monkey brain where a moderate brain uptake was found at the baseline condition. However, it showed fast wash-out as it dropped to half of the peak at around 10 min. Change of VT from baseline was around -10% after pretreatment with a M4 PAM, CVL-231. Radiometabolite studies showed relatively fast metabolism. Although sufficient brain uptake of [11C]PF06885190 was observed, these data suggest that [11C]PF06885190 might have too low specific binding in the NHP brain to be further applied in PET imaging.
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Affiliation(s)
- Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 17164 Stockholm, Sweden
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 17164 Stockholm, Sweden
| | - Zhisheng Jia
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 17164 Stockholm, Sweden
| | - Erik Lachapelle
- Worldwide Research, Development and Medical, Pfizer Inc., Groton, CT 06340, USA
| | - Lei Zhang
- Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Kevin Maresca
- Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Laigao Chen
- Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Mahabuba Jahan
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 17164 Stockholm, Sweden
| | - Timothy Mccarthy
- Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 17164 Stockholm, Sweden
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6
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Nag S, Miranda-Azpiazu P, Jia Z, Datta P, Arakawa R, Moein MM, Yang Z, Tu Y, Lemoine L, Ågren H, Nordberg A, Långström B, Halldin C. Development of 11C-Labeled ASEM Analogues for the Detection of Neuronal Nicotinic Acetylcholine Receptors (α7-nAChR). ACS Chem Neurosci 2022; 13:352-362. [PMID: 35020351 PMCID: PMC8815074 DOI: 10.1021/acschemneuro.1c00730] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 01/04/2022] [Indexed: 12/31/2022] Open
Abstract
The homo-pentameric alpha 7 receptor is one of the major types of neuronal nicotinic acetylcholine receptors (α7-nAChRs) related to cognition, memory formation, and attention processing. The mapping of α7-nAChRs by PET pulls a lot of attention to realize the mechanism and development of CNS diseases such as AD, PD, and schizophrenia. Several PET radioligands have been explored for the detection of the α7-nAChR. 18F-ASEM is the most functional for in vivo quantification of α7-nAChRs in the human brain. The first aim of this study was to initially use results from in silico and machine learning techniques to prescreen and predict the binding energy and other properties of ASEM analogues and to interpret these properties in terms of atomic structures using 18F-ASEM as a lead structure, and second, to label some selected candidates with carbon-11/hydrogen-3 (11C/3H) and to evaluate the binding properties in vitro and in vivo using the labeled candidates. In silico predictions are obtained from perturbation free-energy calculations preceded by molecular docking, molecular dynamics, and metadynamics simulations. Machine learning techniques have been applied for the BBB and P-gp-binding properties. Six analogues of ASEM were labeled with 11C, and three of them were additionally labeled with 3H. Binding properties were further evaluated using autoradiography (ARG) and PET measurements in non-human primates (NHPs). Radiometabolites were measured in NHP plasma. All six compounds were successfully synthesized. Evaluation with ARG showed that 11C-Kln83 was preferably binding to the α7-nAChR. Competition studies showed that 80% of the total binding was displaced. Further ARG studies using 3H-KIn-83 replicated the preliminary results. In the NHP PET study, the distribution pattern of 11C-KIn-83 was similar to other α7 nAChR PET tracers. The brain uptake was relatively low and increased by the administration of tariquidar, indicating a substrate of P-gp. The ASEM blocking study showed that 11C-KIn-83 specifically binds to α7 nAChRs. Preliminary in vitro evaluation of KIn-83 by ARG with both 11C and 3H and in vivo evaluation in NHP showed favorable properties for selectively imaging α7-nAChRs, despite a relatively low brain uptake.
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Affiliation(s)
- Sangram Nag
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
| | - Patricia Miranda-Azpiazu
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
| | - Zhisheng Jia
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
| | - Prodip Datta
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
| | - Ryosuke Arakawa
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
| | - Mohammad Mahdi Moein
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
| | - Zhou Yang
- Department
of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Yaoquan Tu
- Division
of Theoretical Chemistry and Biology, Royal
Institute of Technology (KTH), 11428 Stockholm, Sweden
| | - Laetitia Lemoine
- Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm Sweden
| | - Hans Ågren
- Department
of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Agneta Nordberg
- Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm Sweden
- Theme Aging, Karolinska University
Hospital, 141 52 Stockholm, Sweden
| | - Bengt Långström
- Department
of Chemistry, Uppsala University, 75123 Uppsala, Sweden
| | - Christer Halldin
- Department
of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, 171 76 Stockholm, Sweden
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7
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Nag S, Jahan M, Tóth M, Nakao R, Varrone A, Halldin C. PET Imaging of VMAT2 with the Novel Radioligand [ 18F]FE-DTBZ-d4 in Nonhuman Primates: Comparison with [ 11C]DTBZ and [ 18F]FE-DTBZ. ACS Chem Neurosci 2021; 12:4580-4586. [PMID: 34813272 PMCID: PMC8678981 DOI: 10.1021/acschemneuro.1c00651] [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] [Indexed: 12/26/2022] Open
Abstract
![]()
The vesicular monoamine
transporter type 2 (VMAT2) is believed
to be responsible for the uptake of monoamines into the vesicles of
the synaptic terminals. Two VMAT2 radioligands [11C]DTBZ
and [18F]FP-DTBZ have been used to assess the degree of
nigrostriatal deficit in Parkinson’s disease (PD) using positron
emission tomography (PET). [18F]FE-DTBZ-d4, the nondeuterated
analogue of [18F]FE-DTBZ showed similar imaging properties
with better stability against defluorination. Therefore, [18F]FE-DTBZ-d4 draws attention to be investigated as an imaging marker
for VMAT2 in the brain. The aim of this study was to investigate the
brain kinetics and quantification of [18F]FE-DTBZ-d4 in
nonhuman primates (NHPs), with comparison to [11C]DTBZ
and [18F]FE-DTBZ. Radiolabeling was successfully achieved
either by one-step 11C-methylation or by a two-step fluorine-18
nucleophilic substitution reaction. The stability and radiochemical
yield were analyzed with high-performance liquid chromatography (HPLC).
Three female cynomolgus monkeys were included in the study and underwent
a total of 12 positron emission tomography (PET) measurements. Each
monkey was examined with each tracer. In addition, two pretreatment
and one displacement PET measurements with tetrabenazine (2.0 mg/kg)
were performed for [18F]FE-DTBZ-d4. All PET measurements
were conducted using a high-resolution research tomograph (HRRT) system.
Radiometabolites were measured in monkey plasma using gradient radio-HPLC.
[18F]FE-DTBZ-d4 (SUV: 4.28 ± 1.01) displayed higher
brain uptake compared to both [18F]FE-DTBZ (SUV: 3.43 ±
0.54) and [11C]DTBZ (SUV: 3.06 ± 0.32) and faster
washout. Binding potential (BPND) values of [18F]FE-DTBZ-d4 in different brain regions (putamen: 5.5 ± 1.4;
caudate: 4.4 ± 1.1; midbrain: 1.4 ± 0.4) were higher than
those of [11C]DTBZ and [18F]FE-DTBZ. [18F]FE-DTBZ showed faster radiometabolism in plasma compared to [11C]DTBZ and [18F]FE-DTBZ-d4. [18F]FE-DTBZ-d4
is a suitable radioligand for quantification of VMAT2 in the nonhuman
primate brain, with better imaging properties than [11C]DTBZ
and [18F]FE-DTBZ. A preliminary comparison suggests that
[18F]FE-DTBZ-d4 has increased stability against defluorination
compared to the nondeuterated analogue.
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Affiliation(s)
- Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Mahabuba Jahan
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Miklós Tóth
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Ryuji Nakao
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Andrea Varrone
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
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8
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Liu L, Johnson PD, Prime ME, Khetarpal V, Lee MR, Brown CJ, Chen X, Clark-Frew D, Coe S, Conlon M, Davis R, Ensor S, Esposito S, Moren AF, Gai X, Green S, Greenaway C, Haber J, Halldin C, Hayes S, Herbst T, Herrmann F, Heßmann M, Hsai MM, Kotey A, Mangette JE, Mills MR, Monteagudo E, Nag S, Nibbio M, Orsatti L, Schaertl S, Scheich C, Sproston J, Stepanov V, Varnäs K, Varrone A, Wityak J, Mrzljak L, Munoz-Sanjuan I, Bard JA, Dominguez C. [ 11C]CHDI-626, a PET Tracer Candidate for Imaging Mutant Huntingtin Aggregates with Reduced Binding to AD Pathological Proteins. J Med Chem 2021; 64:12003-12021. [PMID: 34351166 DOI: 10.1021/acs.jmedchem.1c00667] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The expanded polyglutamine-containing mutant huntingtin (mHTT) protein is implicated in neuronal degeneration of medium spiny neurons in Huntington's disease (HD) for which multiple therapeutic approaches are currently being evaluated to eliminate or reduce mHTT. Development of effective and orthogonal biomarkers will ensure accurate assessment of the safety and efficacy of pharmacologic interventions. We have identified and optimized a class of ligands that bind to oligomerized/aggregated mHTT, which is a hallmark in the HD postmortem brain. These ligands are potentially useful imaging biomarkers for HD therapeutic development in both preclinical and clinical settings. We describe here the optimization of the benzo[4,5]imidazo[1,2-a]pyrimidine series that show selective binding to mHTT aggregates over Aβ- and/or tau-aggregates associated with Alzheimer's disease pathology. Compound [11C]-2 was selected as a clinical candidate based on its high free fraction in the brain, specific binding in the HD mouse model, and rapid brain uptake/washout in nonhuman primate positron emission tomography imaging studies.
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Affiliation(s)
- Longbin Liu
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Peter D Johnson
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Michael E Prime
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Vinod Khetarpal
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Matthew R Lee
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Christopher J Brown
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Xuemei Chen
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Daniel Clark-Frew
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Samuel Coe
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Mike Conlon
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Randall Davis
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Samantha Ensor
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Simone Esposito
- IRBM, IRBM Science Park S.p.A., Via Pontina Km 30,600, Pomezia, Rome 00071, Italy
| | - Anton Forsberg Moren
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, Stockholm S-17176, Sweden
| | - Xinjie Gai
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Samantha Green
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Catherine Greenaway
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - James Haber
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Christer Halldin
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, Stockholm S-17176, Sweden
| | - Sarah Hayes
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Todd Herbst
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Frank Herrmann
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, Hamburg 22419, Germany
| | - Manuela Heßmann
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, Hamburg 22419, Germany
| | - Ming Min Hsai
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Adrian Kotey
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - John E Mangette
- Albany Molecular Research, Inc., 1001 Main Street, Buffalo, New York 14203, United States
| | - Matthew R Mills
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Edith Monteagudo
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Sangram Nag
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, Stockholm S-17176, Sweden
| | - Martina Nibbio
- IRBM, IRBM Science Park S.p.A., Via Pontina Km 30,600, Pomezia, Rome 00071, Italy
| | - Laura Orsatti
- IRBM, IRBM Science Park S.p.A., Via Pontina Km 30,600, Pomezia, Rome 00071, Italy
| | - Sabine Schaertl
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, Hamburg 22419, Germany
| | - Christoph Scheich
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, Hamburg 22419, Germany
| | - Joanne Sproston
- Evotec (U.K.) Ltd, 114 Innovation Drive, Milton Park, Abingdon OX14 4RZ, U.K
| | - Vladimir Stepanov
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, Stockholm S-17176, Sweden
| | - Katarina Varnäs
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, Stockholm S-17176, Sweden
| | - Andrea Varrone
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, Stockholm S-17176, Sweden
| | - John Wityak
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Ladislav Mrzljak
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Ignacio Munoz-Sanjuan
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Jonathan A Bard
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
| | - Celia Dominguez
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 700, Los Angeles, California 90045, United States
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9
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Bertoglio D, Verhaeghe J, Miranda A, Wyffels L, Stroobants S, Dominguez C, Munoz-Sanjuan I, Skinbjerg M, Liu L, Staelens S. Kinetic Modelling and Test-Retest Reproducibility for the Dopamine D 1R Radioligand [ 11C]SCH23390 in Healthy and Diseased Mice. Mol Imaging Biol 2020; 23:208-219. [PMID: 33179158 PMCID: PMC7910372 DOI: 10.1007/s11307-020-01561-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 01/25/2023]
Abstract
Purpose Our aim in this study was to compare different non-invasive pharmacokinetic models and assess test–retest reproducibility of the radioligand [11C]SCH23390 for the quantification of dopamine D1-like receptor (D1R) in both wild-type (WT) mice and heterozygous (HET) Q175DN mice as Huntington’s disease (HD) model. Procedures Adult WT (n = 9) and HET (n = 14) mice underwent a 90-min [11C]SCH23390 positron emission tomography (PET) scan followed by computed tomography (CT) to evaluate the pharmacokinetic modelling in healthy and diseased conditions. Additionally, 5 WT mice and 7 HET animals received a second [11C]SCH23390 PET scan for test–retest reproducibility. Parallel assessment of the simplified reference tissue model (SRTM), the multilinear reference tissue model (MRTM) and the Logan reference tissue model (Logan Ref) using the striatum as a receptor-rich region and the cerebellum as a receptor-free (reference) region was performed to define the most suitable method for regional- and voxel-based quantification of the binding potential (BPND). Finally, standardised uptake value ratio (SUVR-1) was assessed as a potential simplified measurement. Results For all models, we measured a significant decline in dopamine D1R density (e.g. SRTM = − 38.5 ± 5.0 %, p < 0.0001) in HET mice compared to WT littermates. Shortening the 90-min scan duration resulted in large underestimation of striatal BPND in both WT mice (SRTM 60 min: − 17.7 ± 2.8 %, p = 0.0078) and diseased HET (SRTM 60 min: − 13.1 ± 4.1 %, p = 0.0001). Striatal BPND measurements were very reproducible with an average test–retest variability below 5 % when using both MRTM and SRTM. Parametric BPND maps generated with SRTM were highly reliable, showing nearly perfect agreement to the regional analysis (r2 = 0.99, p < 0.0001). Finally, SRTM provided the most accurate estimate for relative tracer delivery R1 with both regional- and voxel-based analyses. SUVR-1 at different time intervals were not sufficiently reliable when compared to BPND (r2 < 0.66). Conclusions Ninety-minute acquisition and the use of SRTM for pharmacokinetic modelling is recommended. [11C]SCH23390 PET imaging demonstrates optimal characteristics for the study of dopamine D1R density in models of psychiatric and neurological disorders as exemplified in the Q175DN mouse model of HD. Supplementary Information The online version contains supplementary material available at 10.1007/s11307-020-01561-1.
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Affiliation(s)
- Daniele Bertoglio
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Alan Miranda
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium.,Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium.,Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | | | | | | | - Longbin Liu
- CHDI Management/CHDI Foundation, Los Angeles, CA, USA
| | - Steven Staelens
- Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium.
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10
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Varnäs K, Finnema SJ, Johnström P, Arakawa R, Halldin C, Eriksson LI, Farde L. Effects of sevoflurane anaesthesia on radioligand binding to monoamine oxidase-B in vivo. Br J Anaesth 2020; 126:238-244. [PMID: 33036760 PMCID: PMC8258980 DOI: 10.1016/j.bja.2020.08.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/24/2020] [Accepted: 08/31/2020] [Indexed: 11/28/2022] Open
Abstract
Background The molecular actions underlying the clinical effects of inhaled anaesthetics such as sevoflurane and isoflurane are not fully understood. Unexpected observations in positron emission tomography (PET) studies with [11C]AZD9272, a metabotropic glutamate receptor 5 (mGluR5) radioligand with possible affinity for monoamine oxidase-B (MAO-B), suggest that its binding is sensitive to anaesthesia with sevoflurane. The objective of the present study was to assess the effects of sevoflurane anaesthesia on the binding of [11C]AZD9272 and of [11C]L-deprenyl-D2, a radioligand selective for MAO-B in non-human primates (NHPs). Methods Altogether, 12 PET measurements were conducted with a high-resolution research tomograph using the ligands [11C]AZD9272 or [11C]L-deprenyl-D2 in six cynomolgus monkeys anaesthetised with sevoflurane or ketamine/xylazine. Results The specific binding of [11C]AZD9272 and [11C]L-deprenyl-D2 was markedly reduced during anaesthesia with sevoflurane compared with ketamine/xylazine. The reduction was 80–90% (n=3) for [11C]AZD9272 and 77–80% (n=3) for [11C]L-deprenyl-D2. Conclusions Sevoflurane anaesthesia inhibited radioligand binding to MAO-B in the primate brain. The observation of lower MAO-B binding at clinically relevant concentrations of sevoflurane warrants further exploration of the potential role of MAO-B related mechanisms in regulation of systemic blood pressure during anaesthesia.
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Affiliation(s)
- Katarina Varnäs
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.
| | - Sjoerd J Finnema
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Peter Johnström
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden; PET Science Centre, Precision Medicine and Biosamples, R&D Oncology, AstraZeneca, Karolinska Institutet, Stockholm, Sweden
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Lars I Eriksson
- Perioperative Medicine and Intensive Care, Section for Anesthesiology and Intensive Care Medicine, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
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11
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Lindberg A, Arakawa R, Nogami T, Nag S, Schou M, Elmore CS, Farde L, Pike VW, Halldin C. Potential for imaging the high-affinity state of the 5-HT 1B receptor: a comparison of three PET radioligands with differing intrinsic activity. EJNMMI Res 2019; 9:100. [PMID: 31754940 PMCID: PMC6872687 DOI: 10.1186/s13550-019-0570-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/01/2019] [Indexed: 11/19/2022] Open
Abstract
Background Over the last decade, a few radioligands have been developed for PET imaging of brain 5-HT1B receptors. The 5-HT1B receptor is a G-protein-coupled receptor (GPCR) that exists in two different agonist affinity states. An agonist ligand is expected to be more sensitive towards competition from another agonist, such as endogenous 5-HT, than an antagonist ligand. It is of interest to know whether the intrinsic activity of a PET radioligand for the 5-HT1B receptor impacts on its ability to detect changes in endogenous synaptic 5-HT density. Three high-affinity 11C-labeled 5-HT1B PET radioligands with differing intrinsic activity were applied to PET measurements in cynomolgus monkey to evaluate their sensitivity to be displaced within the brain by endogenous 5-HT. For these experiments, fenfluramine was pre-administered at two different doses (1.0 and 5.0 mg/kg, i.v.) to induce synaptic 5-HT release. Results A dose-dependent response to fenfluramine was detected for all three radioligands. At the highest dose of fenfluramine (5.0 mg/kg, i.v.), reductions in specific binding in the occipital cortex increased with radioligand agonist efficacy, reaching 61% for [11C]3. The most antagonistic radioligand showed the lowest reduction in specific binding. Conclusions Three 5-HT1B PET radioligands were identified with differing intrinsic activity that could be used in imaging high- and low-affinity states of 5-HT1B receptors using PET. From this limited study, radioligand sensitivity to endogenous 5-HT appears to depend on agonist efficacy. More extensive studies are required to substantiate this suggestion.
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Affiliation(s)
- Anton Lindberg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden. .,Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892-1003, USA.
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
| | - Tsuyoshi Nogami
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden.,PET Science Centre, Precision Medicine and Genomics, R&D, AstraZeneca, SE-17176, Stockholm, Sweden
| | - Charles S Elmore
- Isotope Chemistry, Early Chemical Development, Pharmaceutical Sciences R&D, AstraZeneca, SE-43250, Göteborg, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden.,PET Science Centre, Precision Medicine and Genomics, R&D, AstraZeneca, SE-17176, Stockholm, Sweden
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892-1003, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
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12
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Lindberg A, Nag S, Schou M, Arakawa R, Nogami T, Moein MM, Elmore CS, Pike VW, Halldin C. Development of a 18F-labeled PET radioligand for imaging 5-HT 1B receptors: [ 18F]AZ10419096. Nucl Med Biol 2019; 78-79:11-16. [PMID: 31678782 PMCID: PMC10114145 DOI: 10.1016/j.nucmedbio.2019.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/01/2019] [Accepted: 10/20/2019] [Indexed: 02/06/2023]
Abstract
INTRODUCTION In the last decade PET has been useful in studying and understanding the 5-HT1B receptor. [11C]AZ10419369 and [11C]P943 have been applied as radioligands in these studies. Both use carbon-11 (t1/2 = 20.4 min) as radionuclide, which limits the application to PET centres that have an on-site cyclotron and radiochemistry facilities. In this paper we report the synthesis and initial evaluation of the first fluorine-18 PET radioligand to image 5-HT1B receptors in brain, [18F]AZ10419096. MATERIALS AND METHODS A boronate-precursor for [18F]AZ10419096 was synthesized from an intermediate provided by AstraZeneca and was labeled with fluorine 18 using Cu-mediated radio-fluorination. [18F]AZ10419096 was used in PET baseline and pretreatment measurements in nonhuman primates. PET data were analyzed using SRTM using the cerebellum as reference region. Blood samples for radio-metabolite analysis were collected during PET measurements. RESULTS Radio-fluorination gave [18F]AZ10419096 in sufficient amounts and molar activity and with high radiochemical purity to be applied in PET measurements. In a baseline PET measurement [18F]AZ10419096 showed a high brain uptake and regional distribution consistent with reported 5-HT1B receptor densities. In a pretreatment PET measurement, AR-A000002 (2.0 mg/kg) blocked the binding of [18F]AZ10419096 to 5-HT1B receptors in occipital cortex by 80%, thereby demonstrating high specific binding. CONCLUSION [18F]AZ10419096 is the first fluorine-18 PET radioligand for imaging 5-HT1B receptors in vivo with high specific binding and binding potential. [18F]AZ10419096 is a candidate for further development for use in clinical PET studies.
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Affiliation(s)
- Anton Lindberg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden; Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA.
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden; PET Science Centre, Precision Medicine and Genomics, R&D, AstraZeneca, SE-17176 Stockholm, Sweden
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Tsuyoshi Nogami
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Mohammad Mahdi Moein
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Charles S Elmore
- Isotope Chemistry, Early Chemical Development, Pharmaceutical Sciences R&D, AstraZeneca, SE-43250 Göteborg, Sweden
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
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13
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The pro-psychotic metabotropic glutamate receptor compounds fenobam and AZD9272 share binding sites with monoamine oxidase-B inhibitors in humans. Neuropharmacology 2019; 162:107809. [PMID: 31589885 DOI: 10.1016/j.neuropharm.2019.107809] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 09/18/2019] [Accepted: 10/02/2019] [Indexed: 11/22/2022]
Abstract
The metabotropic glutamate receptor 5 (mGluR5) ligands fenobam and AZD9272 have been reported to induce psychosis-like adverse events and to bind at unknown, non-GluR5-related, sites. Based on similarities of the regional binding patterns for [11C]AZD9272 and the monoamine oxidase-B (MAO-B) radioligand [11C]L-deprenyl-D2 in PET studies of the human brain we tested the hypothesis that the unique binding of fenobam and AZD9272 may represent specific binding to the MAO-B. PET data previously acquired for subjects examined using [11C]AZD9272 or [11C]L-deprenyl-D2 were re-evaluated to assess the correlations between radioligand binding parameters in human brain. In addition, the pharmacology of AZD9272 binding sites was characterized using competition binding studies carried out in vivo in non-human primates (NHPs) and in vitro using autoradiography in selected human brain regions. The regional binding of [11C]AZD9272 in human brain was closely correlated with that of [11C]L-deprenyl-D2. In PET studies of NHP brain administration of the MAO-B ligand L-deprenyl inhibited binding of radiolabeled AZD9272 and administration of fenobam inhibited binding of [11C]L-deprenyl-D2. Binding of radiolabeled AZD9272 in vitro was potently inhibited by fenobam or MAO-B compounds, and [11C]L-deprenyl-D2 binding was inhibited by fenobam or AZD9272. The findings are consistent with the hypothesis that both fenobam and AZD9272 bind to the MAO-B, which may be of relevance for understanding the mechanism of the psychosis-like adverse events reported for these compounds. Such understanding may serve as a lead to generate new models for the pathophysiology of psychosis.
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14
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Takano A, Uz T, Garcia-Segovia J, Tsai M, Lahu G, Amini N, Nakao R, Jia Z, Halldin C. A Nonhuman Primate PET Study: Measurement of Brain PDE4 Occupancy by Roflumilast Using (R)-[ 11C]Rolipram. Mol Imaging Biol 2019; 20:615-622. [PMID: 29441434 DOI: 10.1007/s11307-018-1168-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE Phosphodiesterase 4 (PDE4) inhibition in the brain has been reported to improve cognitive function in animal models. Therefore, PDE4 inhibitors are one of key targets potential for drug development. Investigation of brain PDE4 occupancy would help to understand the effects of PDE4 inhibition to cognitive functions. Roflumilast is a selective phosphodiesterase type 4 (PDE4) inhibitor used clinically for severe chronic obstructive pulmonary disease, but the effects to the brain have not been well investigated. In this study, we aimed to investigate whether roflumilast entered the brain and occupied PDE4 in nonhuman primates. PROCEDURES Positron emission tomography (PET) measurements with (R)-[11C]rolipram were performed at baseline and after intravenous (i.v.) administration of roflumilast (3.6 to 200 μg/kg) in three female rhesus monkeys. Arterial blood samples were taken to obtain the input function. Protein binding was measured to obtain the free fraction (fp) of the radioligand. Total distribution volume (VT) and VT/fp were calculated as outcome measures from two tissue compartment model. Lassen plot approach was taken to estimate the target occupancy. RESULTS The brain uptake of (R)-[11C]rolipram decreased after roflumilast administration. PDE 4 occupancy by roflumilast showed dose- and plasma concentration-dependent increase, although PDE4 occupancy did not reach 50 % even after the administration of up to 200 μg/kg of roflumilast, regardless of outcome measures, VT or VT/fp. CONCLUSIONS This PET study showed that the brain PDE4 binding was blocked to a certain extent after i.v. administration of clinical relevant doses of roflumilast in nonhuman primates. Further clinical PET evaluation is needed to understand the relationship between PDE4 inhibition and potential improvement of cognitive function in human subjects.
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Affiliation(s)
- Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden.
| | - Tolga Uz
- Takeda Development Center Americas, Inc., Deerfield, IL, 60015, USA
| | - Jesus Garcia-Segovia
- Takeda Development Center, London, UK.,Orchard Therapeuitcs, Birchin Lane, London, UK
| | - Max Tsai
- Takeda Development Center Americas, Inc., Deerfield, IL, 60015, USA.,Eli Lilly and Company, Indianapolis, IN, USA
| | - Gezim Lahu
- Takeda Development Center Americas, Inc., Deerfield, IL, 60015, USA
| | - Nahid Amini
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Ryuji Nakao
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Zhisheng Jia
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
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15
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Schou M, Ewing P, Cselenyi Z, Fridén M, Takano A, Halldin C, Farde L. Pulmonary PET imaging confirms preferential lung target occupancy of an inhaled bronchodilator. EJNMMI Res 2019; 9:9. [PMID: 30694407 PMCID: PMC6890867 DOI: 10.1186/s13550-019-0479-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 01/21/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Positron emission tomography (PET) is a non-invasive molecular imaging technique that traces the distribution of radiolabeled molecules in experimental animals and human subjects. We hypothesized that PET could be used to visualize the binding of the bronchodilator drug ipratropium to muscarinic receptors (MR) in the lungs of living non-human primates (NHP). The objectives of this study were two-fold: (i) to develop a methodology for quantitative imaging of muscarinic receptors in NHP lung and (ii) to estimate and compare ipratropium-induced MR occupancy following drug administration via intravenous injection and inhalation, respectively. METHODS A series of PET measurements (n = 18) was performed after intravenous injection of the selective muscarinic radioligand 11C-VC-002 in NHP (n = 5). The lungs and pituitary gland (both rich in MR) were kept in the field of view. Each PET measurement was followed by a PET measurement preceded by treatment with ipratropium (intravenous or inhaled). RESULTS Radioligand binding was quantified using the Logan graphical analysis method providing the total volume of distribution (VT). Ipratropium reduced the VT in the lung and pituitary in a dose-dependent fashion. At similar plasma ipratropium concentrations, administration by inhalation produced larger reductions in VT for the lungs. The plasma-derived apparent affinity for ipratropium binding in the lung was one order of magnitude higher after inhalation (Kiih = 1.01 nM) than after intravenous infusion (Kiiv = 10.84 nM). CONCLUSION Quantitative muscarinic receptor occupancy imaging by PET articulates and quantifies the therapeutic advantage of the inhaled route of delivery and provides a tool for future developments of improved inhaled drugs.
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Affiliation(s)
- Magnus Schou
- PET Science Centre, Precision Medicine and Genomics, IMED Biotech Unit, AstraZeneca, Karolinska Institutet, Stockholm, Sweden. .,Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76, Stockholm, Sweden.
| | - Pär Ewing
- Respiratory, Inflammation and Autoimmunity IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Zsolt Cselenyi
- PET Science Centre, Precision Medicine and Genomics, IMED Biotech Unit, AstraZeneca, Karolinska Institutet, Stockholm, Sweden
| | - Markus Fridén
- Respiratory, Inflammation and Autoimmunity IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden.,Translational PKPD, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76, Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76, Stockholm, Sweden
| | - Lars Farde
- PET Science Centre, Precision Medicine and Genomics, IMED Biotech Unit, AstraZeneca, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76, Stockholm, Sweden
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16
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Lindberg A, Lu S, Nag S, Schou M, Liow JS, Zoghbi SS, Frankland MP, Gladding RL, Morse CL, Takano A, Amini N, Elmore CS, Lee YS, Innis RB, Halldin C, Pike VW. Synthesis and evaluation of two new candidate high-affinity full agonist PET radioligands for imaging 5-HT 1B receptors. Nucl Med Biol 2019; 70:1-13. [PMID: 30811975 DOI: 10.1016/j.nucmedbio.2019.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/17/2019] [Accepted: 01/21/2019] [Indexed: 11/17/2022]
Abstract
INTRODUCTION The serotonin 1B receptor subtype is of interest in the pathophysiology and treatment of depression, anxiety, and migraine. Over recent years 5-HT1B receptor binding in human brain has been examined with PET using radioligands that are partial but not full agonists. To explore how the intrinsic activity of a PET radioligand may affect imaging performance, two high-affinity full 5-HT1B receptor agonists (AZ11136118, 4; and AZ11895987, 5) were selected from a large compound library and radiolabeled for PET examination in non-human primates. METHODS [11C]4 was obtained through Pd(0)-mediated insertion of [11C]carbon monoxide between prepared iodoarene and homochiral amine precursors. [11C]5 was obtained through N-11C-methylation of N-desmethyl precursor 6 with [11C]methyl triflate. [11C]4 and [11C]5 were studied with PET in rhesus or cynomolgus monkey. [11C]4 was studied with PET in mice and rats to measure brain uptake and specific binding. Ex-vivo experiments in rats were performed to identify whether there were radiometabolites in brain. Physiochemical parameters for [11C]4 (pKa, logD and conformational energetics) were evaluated. RESULTS Both [11C]4 and [11C]5 were successfully produced in high radiochemical purity and in adequate amounts for PET experiments. After intravenous injection of [11C]4, brain radioactivity peaked at a low level (0.2 SUV). Pretreatment with tariquidar, an inhibitor of the brain P-gp efflux transporter, increased brain exposure four-fold whereas pretreatment with a high pharmacological dose of the 5-HT1B antagonist, AR-A000002, had no effect on the binding. Ex-vivo experiments in rats showed no radiometabolites entering brain. [11C]5 also failed to enter monkey brain under baseline conditions. CONCLUSIONS [11C]4 and [11C]5 show too low brain uptake and specific binding to be useful PET radioligands. Low brain uptake is partly ascribed to efflux transporter action as well as unfavorable conformations.
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Affiliation(s)
- Anton Lindberg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden; Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA.
| | - Shuiyu Lu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden; PET Science Centre, Precision Medicine and Genomics, IMED Biotech Unit, AstraZeneca, SE-17176 Stockholm, Sweden
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Michael P Frankland
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Robert L Gladding
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Nahid Amini
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Charles S Elmore
- Isotope Chemistry, Early Chemical Development, Pharmaceutical Sciences, IMED Biotech Unit, AstraZeneca, SE-43250 Göteborg, Sweden
| | - Yong Sok Lee
- Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892-5624, USA
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176 Stockholm, Sweden
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA
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Varnäs K, Juréus A, Finnema SJ, Johnström P, Raboisson P, Amini N, Takano A, Stepanov V, Halldin C, Farde L. The metabotropic glutamate receptor 5 radioligand [ 11C]AZD9272 identifies unique binding sites in primate brain. Neuropharmacology 2018; 135:455-463. [PMID: 29608920 DOI: 10.1016/j.neuropharm.2018.03.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 03/25/2018] [Accepted: 03/29/2018] [Indexed: 12/11/2022]
Abstract
The metabotropic glutamate receptor 5 (mGluR5) is a target for drug development and for imaging studies of the glutamate system in neurological and psychiatric disorders. [11C]AZD9272 is a selective mGluR5 PET radioligand that is structurally different from hitherto applied mGluR5 radioligands. In the present investigation we compared the binding patterns of radiolabeled AZD9272 and other mGluR5 radioligands in the non-human primate (NHP) brain. PET studies were undertaken using [11C]AZD9272 and the commonly applied mGluR5 radioligand [11C]ABP688. Autoradiography studies were performed in vitro using [3H]AZD9272 and the standard mGluR5 radioligands [3H]M-MTEP and [3H]ABP688 in NHP tissue. Competition binding studies were undertaken in vivo and in vitro using different mGluR5 selective compounds as inhibitors. In comparison to other mGluR5 radioligands radiolabeled AZD9272 displayed a distinct regional distribution pattern with high binding in ventral striatum, midbrain, thalamus and cerebellum. While the binding of [11C]AZD9272 was almost completely inhibited by the structurally unique mGluR5 compound fenobam (2.0 mg/kg; 98% occupancy), it was only partially inhibited (46% and 20%, respectively) by the mGluR5 selective compounds ABP688 and MTEP, at a dose (2.0 mg/kg) expected to saturate the mGluR5. Autoradiography studies using [3H]AZD9272 confirmed a distinct pharmacologic profile characterized by preferential sensitivity to fenobam. The distinctive binding in ventral striato-pallido-thalamic circuits and shared pharmacologic profile with the pro-psychotic compound fenobam warrants further examination of [11C]AZD9272 for potential application in psychiatric neuroimaging studies.
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Affiliation(s)
- Katarina Varnäs
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.
| | | | - Sjoerd J Finnema
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Peter Johnström
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden; PET Science Centre, Precision Medicine and Genomics, IMED Biotech Unit, AstraZeneca, Karolinska Institutet, Sweden
| | | | - Nahid Amini
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Vladimir Stepanov
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden; PET Science Centre, Precision Medicine and Genomics, IMED Biotech Unit, AstraZeneca, Karolinska Institutet, Sweden
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18
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Abstract
The dopamine (DA) system is considered to be centrally involved in the pathophysiology of several major psychiatric disorders. Using positron emission tomography (PET), aberrations in dopamine D2/D3-receptors (D2-R) levels and uptake of the DA precursor FDOPA have been shown for schizophrenia, substance abuse and depression. Radioligands for the dopamine D1-receptor (D1-R) have been available for more than three decades, however this receptor subtype has received much less attention in psychiatry research. Here, studies investigating D1-R in psychiatric patients in comparison to healthy control subjects are summarized. Although small sample sizes, medication effects and heterogeneous methods of quantification limit the conclusions that can be drawn, the data is suggestive of higher levels of cortical D1-R in drug naïve patients with psychosis, and lower D1-R in patients with affective disorders. Data sharing and reanalysis using harmonized methodology are important next steps towards clarifying the role of D1-R in these disorders.
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Affiliation(s)
- Simon Cervenka
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden.
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19
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Malmquist J, Varnäs K, Svedberg M, Vallée F, Albert JS, Finnema SJ, Schou M. Discovery of a Novel Muscarinic Receptor PET Radioligand with Rapid Kinetics in the Monkey Brain. ACS Chem Neurosci 2018; 9:224-229. [PMID: 29072902 DOI: 10.1021/acschemneuro.7b00340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Positron emission tomography (PET), together with a suitable radioligand, is one of the more prominent methods for measuring changes in synaptic neurotransmitter concentrations in vivo. The radioligand of choice for such measurements on the cholinergic system is the muscarinic receptor antagonist N-[1-11C]propyl-3-piperidyl benzilate (PPB). In an effort to overcome the shortcomings with the technically cumbersome synthesis of [11C]PPB, we designed and synthesized four structurally related analogues of PPB, of which (S,R)-1-methylpiperidin-3-yl)2-cyclopentyl-2-hydroxy-2-phenylacetate (1) was found to bind muscarinic receptors with similar affinity as PPB (3.5 vs 7.9 nM, respectively). (S,R)-1 was radiolabeled via N-11C-methylation at high radiochemical purity (>99%) and high specific radioactivity (>130 GBq/μmol). In vitro studies by autoradiography on human brain tissue and in vivo studies by PET in nonhuman primates demonstrated excellent signal-to-noise ratios and a kinetic profile in brain comparable to that of [11C]PBB. (S,R)-[11C]1 is a promising candidate for measuring changes in endogenous acetylcholine concentrations.
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Affiliation(s)
- Jonas Malmquist
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm Country Council, SE-171 76 Stockholm, Sweden
| | - Katarina Varnäs
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm Country Council, SE-171 76 Stockholm, Sweden
| | - Marie Svedberg
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm Country Council, SE-171 76 Stockholm, Sweden
| | | | | | - Sjoerd J. Finnema
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm Country Council, SE-171 76 Stockholm, Sweden
| | - Magnus Schou
- Department
of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm Country Council, SE-171 76 Stockholm, Sweden
- PET Science Centre at Karolinska Institutet, Personalised Healthcare and Biomarkers, AstraZeneca R&D, SE-171 76 Stockholm, Sweden
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20
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Development of two fluorine-18 labeled PET radioligands targeting PDE10A and in vivo PET evaluation in nonhuman primates. Nucl Med Biol 2017; 57:12-19. [PMID: 29223715 DOI: 10.1016/j.nucmedbio.2017.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/02/2017] [Accepted: 10/20/2017] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Phosphodiesterase 10A (PDE10A) is a member of the PDE enzyme family that degrades cyclic adenosine and guanosine monophosphates (cAMP and cGMP). Based on the successful development of [11C]T-773 as PDE10A positron emission tomography (PET) radioligand, in this study our aim was to develop and evaluate fluorine-18 analogs of [11C]T-773. METHODS [18F]FM-T-773-d2 and [18F]FE-T-773-d4 were synthesized from the same precursor used for 11C-labeling of T-773 in a two-step approach via 18F-fluoromethylation and 18F-fluoroethylation, respectively, using corresponding deuterated synthons. A total of 12 PET measurements were performed in seven non-human primates. First, baseline PET measurements were performed using High Resolution Research Tomograph system with both [18F]FM-T-773-d2 and [18F]FE-T-773-d4; the uptake in whole brain and separate brain regions, as well as the specific binding and tissue ratio between putamen and cerebellum, was examined. Second, baseline and pretreatment PET measurements using MP-10 as the blocker were performed for [18F]FM-T-773-d2 including arterial blood sampling with radiometabolite analysis in four NHPs. RESULTS Both [18F]FM-T-773-d2 and [18F]FE-T-773-d4 were successfully radiolabeled with an average molar activity of 293 ± 114 GBq/μmol (n=8) for [18F]FM-T-773-d2 and 209 ± 26 GBq/μmol (n=4) for [18F]FE-T-773-d4, and a radiochemical yield of 10% (EOB, n=12, range 3%-16%). Both radioligands displayed high brain uptake (~5.5% of injected radioactivity for [18F]FM-T-773-d2 and ~3.5% for [18F]FE-T-773-d4 at the peak) and a fast washout. Specific binding reached maximum within 30 min for [18F]FM-T-773-d2 and after approximately 45 min for [18F]FE-T-773-d4. [18F]FM-T-773-d2 data fitted well with kinetic compartment models. BPND values obtained indirectly through compartment models were correlated well with those obtained by SRTM. BPND calculated with SRTM was 1.0-1.7 in the putamen. The occupancy with 1.8 mg/kg of MP-10 was approximately 60%. CONCLUSIONS [18F]FM-T-773-d2 and [18F]FE-T-773-d4 were developed as fluorine-18 PET radioligands for PDE10A, with the [18F]FM-T-773-d2 being the more promising PET radioligand warranting further evaluation.
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21
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Lindberg A, Nag S, Schou M, Takano A, Matsumoto J, Amini N, Elmore CS, Farde L, Pike VW, Halldin C. [ 11C]AZ10419096 - a full antagonist PET radioligand for imaging brain 5-HT 1B receptors. Nucl Med Biol 2017; 54:34-40. [PMID: 28950161 DOI: 10.1016/j.nucmedbio.2017.07.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/05/2017] [Accepted: 07/14/2017] [Indexed: 10/19/2022]
Abstract
INTRODUCTION The serotonergic system is widely present in all regions of the central nervous system (CNS) and plays a key modulatory role in many of its functions. Positron emission tomography (PET) is used to study several serotonin receptors in CNS in vivo. The G-protein coupled receptor 5-HT1B is mostly present in the occipital cortex and in midbrain and is linked to several psychiatric disorders. There is evidence that agonist PET radioligands for neuroreceptors are more sensitive to endogenous neurotransmitters than antagonists. Our previously developed 5-HT1B receptor PET radioligand, [11C]AZ10419369, is now considered a partial agonist. In this work we are aiming to develop a full antagonist PET radioligand for imaging brain 5-HT1B receptors, and evaluate its sensitivity to increased endogenous serotonin concentration. MATERIALS [11C]AZ10419096 was synthesized by rapid methylation of the prepared corresponding N-desmethyl precursor with [11C]methyl triflate. Five PET measurements were performed in cynomolgus monkeys, consisting of two at baseline, one after treatment of a monkey with a 5-HT1B antagonist, AR-A000002, and two in which fenfluramine was administered during scanning to induce endogenous serotonin release. RESULTS AND DISCUSSION [11C]AZ10419096 was synthesized in high yield and purity within 30 min, including purification, formulation and sterile filtration. The baseline PET measurements demonstrated [11C]AZ10419096 to have favorable radioligand characteristics, including high specific binding in brain regions that have high 5-HT1B density, such as occipital cortex and globus pallidus, as well as subsequent rapid elimination from brain and a minor abundance of lipophilic radiometabolites in plasma. AR-A00002 completely blocked radioligand receptor-specific binding. Fenfluramine produced a distinct displacement of radioligand consistent with an expected increase of synaptic endogenous serotonin concentration. CONCLUSIONS [11C]AZ10419096, a full 5-HT1B antagonist PET radioligand, demonstrates high specific binding in monkey brain that is sensitive to competition from a known 5-HT1B antagonist as well as to putatively increased endogenous serotonin levels.
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Affiliation(s)
- Anton Lindberg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden.
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden; AstraZeneca, Personalised Healthcare and Biomarkers, AstraZeneca PET Science Centre, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Junya Matsumoto
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Nahid Amini
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
| | - Charles S Elmore
- Isotope chemistry, Early Chemical Development, Pharmaceutical Sciences Innovative Medicines and Early Development, AstraZeneca, Mölndal, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden; AstraZeneca, Personalised Healthcare and Biomarkers, AstraZeneca PET Science Centre, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-171 76 Stockholm, Sweden
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22
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Varnas K, Jureus A, Johnstrom P, Ahlgren C, Schott P, Schou M, Gruber S, Jerning E, Malmborg J, Halldin C, Afzelius L, Farde L. Integrated Strategy for Use of Positron Emission Tomography in Nonhuman Primates to Confirm Multitarget Occupancy of Novel Psychotropic Drugs: An Example with AZD3676. ACTA ACUST UNITED AC 2016; 358:464-71. [DOI: 10.1124/jpet.116.234146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/06/2016] [Indexed: 01/10/2023]
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23
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Varnäs K, Finnema SJ, Stepanov V, Takano A, Tóth M, Svedberg M, Møller Nielsen S, Khanzhin NA, Juhl K, Bang-Andersen B, Halldin C, Farde L. Neurokinin-3 Receptor Binding in Guinea Pig, Monkey, and Human Brain: In Vitro and in Vivo Imaging Using the Novel Radioligand, [18F]Lu AF10628. Int J Neuropsychopharmacol 2016; 19:pyw023. [PMID: 26993630 PMCID: PMC5006196 DOI: 10.1093/ijnp/pyw023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 03/10/2016] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Previous autoradiography studies have suggested a marked interspecies variation in the neuroanatomical localization and expression levels of the neurokinin 3 receptor, with high density in the brain of rat, gerbil, and guinea pig, but at the time offered no conclusive evidence for its presence in the human brain. Hitherto available radioligands have displayed low affinity for the human neurokinin 3 receptor relative to the rodent homologue and may thus not be optimal for cross-species analyses of the expression of this protein. METHODS A novel neurokinin 3 receptor radioligand, [(18)F]Lu AF10628 ((S)-N-(cyclobutyl(3-fluorophenyl)methyl)-8-fluoro-2-((3-[(18)F]-fluoropropyl)amino)-3-methyl-1-oxo-1,2-dihydroisoquinoline-4-carboxamide), was synthesized and used for autoradiography studies in cryosections from guinea pig, monkey, and human brain as well as for positron emission tomography studies in guinea pig and monkey. RESULTS The results confirmed previous observations of interspecies variation in the neurokinin 3 receptor brain localization with more extensive distribution in guinea pig than in primate brain. In the human brain, specific binding to the neurokinin 3 receptor was highest in the amygdala and in the hypothalamus and very low in other regions examined. Positron emission tomography imaging showed a pattern consistent with that observed using autoradiography. The radioactivity was, however, found to accumulate in skull bone, which limits the use of this radioligand for in vivo quantification of neurokinin 3 receptor binding. CONCLUSION Species differences in the brain distribution of neurokinin 3 receptors should be considered when using animal models for predicting human neurokinin 3 receptor pharmacology. For positron emission tomography imaging of brain neurokinin 3 receptors, additional work is required to develop a radioligand with more favorable in vivo properties.
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Affiliation(s)
- Katarina Varnäs
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatry Research, Stockholm, Sweden (Drs Varnäs, Finnema, Stepanov, Takano, Tóth, Svedberg, Halldin, and Farde); Lundbeck Research, H. Lundbeck A/S, 9 Ottiliavej, DK-2500 Copenhagen-Valby, Denmark (Drs Møller Nielsen, Khanzhin, Juhl, and Bang-Andersen); AstraZeneca Translational Science Centre at Karolinska Institutet, PET CoE, Stockholm, Sweden (Dr Farde).Present address: Glycom A/S, Diplomvej 373, 1, DK-2800 Kgs. Lyngby, Denmark (N.A.K.).
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Takano A, Stepanov V, Nakao R, Amini N, Gulyás B, Kimura H, Halldin C. Brain PET measurement of PDE10A occupancy by TAK-063, a new PDE10A inhibitor, using [11C]T-773 in nonhuman primates. Synapse 2016; 70:253-63. [DOI: 10.1002/syn.21896] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 02/02/2016] [Accepted: 02/10/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatric Research; Karolinska Institutet; Stockholm Sweden
| | - Vladimir Stepanov
- Department of Clinical Neuroscience, Center for Psychiatric Research; Karolinska Institutet; Stockholm Sweden
| | - Ryuji Nakao
- Department of Clinical Neuroscience, Center for Psychiatric Research; Karolinska Institutet; Stockholm Sweden
| | - Nahid Amini
- Department of Clinical Neuroscience, Center for Psychiatric Research; Karolinska Institutet; Stockholm Sweden
| | - Balázs Gulyás
- Department of Clinical Neuroscience, Center for Psychiatric Research; Karolinska Institutet; Stockholm Sweden
| | - Haruhide Kimura
- Pharmaceutical Research Division; CNS Drug Discovery Unit, Takeda Pharmaceutical Company Limited; Fujisawa Japan
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatric Research; Karolinska Institutet; Stockholm Sweden
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25
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Schou M, Varnäs K, Jureus A, Ahlgren C, Malmquist J, Häggkvist J, Tari L, Wesolowski SS, Throner SR, Brown DG, Nilsson M, Johnström P, Finnema SJ, Nakao R, Amini N, Takano A, Farde L. Discovery and Preclinical Validation of [(11)C]AZ13153556, a Novel Probe for the Histamine Type 3 Receptor. ACS Chem Neurosci 2016; 7:177-84. [PMID: 26529287 DOI: 10.1021/acschemneuro.5b00268] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED The histamine type 3 receptor (H3) is a G protein-coupled receptor implicated in several disorders of the central nervous system. Herein, we describe the radiolabeling and preclinical evaluation of a candidate radioligand for the H3 receptor, 4-(1S,2S)-2-(4-cyclobutylpiperazine-1-carbonyl)cyclopropyl]-N-methyl-benzamide (5), and its comparison with one of the frontrunner radioligands for H3 imaging, namely, GSK189254 (1). Compounds 1 and 5 were radiolabeled with tritium and carbon-11 for in vitro and in vivo imaging experiments. The in vitro binding of [(3)H]1 and [(3)H]5 was examined by (i) saturation binding to rat and nonhuman primate brain tissue homogenate and (ii) in vitro autoradiography on tissue sections from rat, guinea pig, and human brain. The in vivo binding of [(11)C]1 and [(11)C]5 was examined by PET imaging in mice and nonhuman primates. Bmax values obtained from Scatchard analysis of [(3)H]1 and [(3)H]5 binding were in good agreement. Autoradiography with [(3)H]5 on rat, guinea pig, and human brain slices showed specific binding in regions known to be enhanced in H3 receptors, a high degree of colocalization with [(3)H]1, and virtually negligible nonspecific binding in tissue. PET measurements in mice and nonhuman primates demonstrated that [(11)C]5 binds specifically and reversibly to H3 receptors in vivo with low nonspecific binding in brain tissue. Whereas [(11)C]1 showed similar binding characteristics in vivo, the binding kinetics appeared faster for [(11)C]5 than for [(11)C]1. CONCLUSIONS [(11)C]5 has suitable properties for quantification of H3 receptors in nonhuman primate brain and has the potential to offer improved binding kinetics in man compared to [(11)C]1.
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Affiliation(s)
- Magnus Schou
- AstraZeneca Translational
Science Centre at Karolinska Institutet, PET Centre of Excellence,
Department of Clinical Neuroscience, S-17176 Stockholm, Sweden
| | - Katarina Varnäs
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Anders Jureus
- AstraZeneca, Research & Development, Innovative Medicines, S-151 85 Södertälje, Sweden
| | - Charlotte Ahlgren
- AstraZeneca, Research & Development, Innovative Medicines, S-151 85 Södertälje, Sweden
| | - Jonas Malmquist
- AstraZeneca, Research & Development, Innovative Medicines, S-151 85 Södertälje, Sweden
| | - Jenny Häggkvist
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Lenke Tari
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Steven S. Wesolowski
- AstraZeneca, Research & Development, Innovative Medicines, Cambridge, Massachusetts 02451, United States
| | - Scott R. Throner
- AstraZeneca, Research & Development, Innovative Medicines, Waltham, Massachusetts 02139, United States
| | - Dean G. Brown
- AstraZeneca, Research & Development, Innovative Medicines, Waltham, Massachusetts 02139, United States
| | - Maria Nilsson
- AstraZeneca, Research & Development, Innovative Medicines, S-151 85 Södertälje, Sweden
| | - Peter Johnström
- AstraZeneca Translational
Science Centre at Karolinska Institutet, PET Centre of Excellence,
Department of Clinical Neuroscience, S-17176 Stockholm, Sweden
| | - Sjoerd J. Finnema
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Ryuji Nakao
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Nahid Amini
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Akihiro Takano
- Department
of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-17176 Stockholm, Sweden
| | - Lars Farde
- AstraZeneca Translational
Science Centre at Karolinska Institutet, PET Centre of Excellence,
Department of Clinical Neuroscience, S-17176 Stockholm, Sweden
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Finnema SJ, Halldin C, Bang-Andersen B, Bundgaard C, Farde L. Serotonin transporter occupancy by escitalopram and citalopram in the non-human primate brain: a [(11)C]MADAM PET study. Psychopharmacology (Berl) 2015; 232:4159-67. [PMID: 25980484 DOI: 10.1007/s00213-015-3961-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/05/2015] [Indexed: 11/29/2022]
Abstract
RATIONALE A number of serotonin receptor positron emission tomography (PET) radioligands have been shown to be sensitive to changes in extracellular serotonin concentration, in a generalization of the well-known dopamine competition model. High doses of selective serotonin reuptake inhibitors (SSRIs) decrease serotonin receptor availability in monkey brain, consistent with increased serotonin concentrations. However, two recent studies on healthy human subjects, using a single, lower and clinically relevant SSRI dose, showed increased cortical serotonin receptor radioligand binding, suggesting potential decreases in serotonin concentration in projection regions when initiating treatment. OBJECTIVES The cross-species differential SSRI effect may be partly explained by serotonin transporter (SERT) occupancy in monkey brain being higher than is clinically relevant. We here determine SERT occupancy after single doses of escitalopram or citalopram by conducting PET measurements with [(11)C]MADAM in monkeys. Relationships between dose, plasma concentration and SERT occupancy were estimated by one-site binding analyses. Binding affinity was expressed as dose (ID50) or plasma concentration (K i) where 50 % SERT occupancy was achieved. RESULTS Estimated ID50 and K i values were 0.020 mg/kg and 9.6 nmol/L for escitalopram and 0.059 mg/kg and 9.7 nmol/L for citalopram, respectively. Obtained K i values are comparable to values reported in humans. CONCLUSIONS Escitalopram or citalopram doses nearly saturated SERT in previous monkey studies which examined serotonin sensitivity of receptor radioligands. PET-measured cross-species differential effects of SSRI on cortical serotonin concentration may thus be related to SSRI dose. Future monkey studies using SSRI doses inducing clinically relevant SERT occupancy may further illuminate the delayed onset of SSRI therapeutic effects.
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Affiliation(s)
- Sjoerd J Finnema
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Karolinska University Hospital, Building R5:02, SE-17176, Stockholm, Sweden. .,Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Karolinska University Hospital, Building R5:02, SE-17176, Stockholm, Sweden
| | | | | | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Karolinska University Hospital, Building R5:02, SE-17176, Stockholm, Sweden.,AstraZeneca, Translational Science Center at Karolinska Institutet, Stockholm, Sweden
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Rahman O, Takano A, Amini N, Dahl K, Kanegawa N, Långström B, Farde L, Halldin C. Synthesis of ([(11)C]carbonyl)raclopride and a comparison with ([(11)C]methyl)raclopride in a monkey PET study. Nucl Med Biol 2015; 42:893-8. [PMID: 26272268 DOI: 10.1016/j.nucmedbio.2015.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 07/05/2015] [Accepted: 07/12/2015] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The selective dopamine D2 receptor antagonist raclopride is usually labeled with carbon-11 using [(11)C]methyl iodide or [(11)C]methyl triflate for use in the quantification of dopamine D2 receptors in human brain. The aim of this work was to label raclopride at the carbonyl position using [(11)C]carbon monoxide chemistry and to compare ([(11)C]carbonyl)raclopride with ([(11)C]methyl)raclopride in non-human primate (NHP) using PET with regard to quantitative outcome measurement, metabolism of the labeled tracers and protein binding. METHODS Palladium-mediated carbonylation using [(11)C]carbon monoxide, 4,6-dichloro-2-iodo-3-methoxyphenol and (S)-(-)-2-aminomethyl-1-ethylpyrrolidine was applied in the synthesis of ([(11)C]carbonyl)raclopride. The reaction was performed at atmospheric pressure using xantphos as supporting phosphine ligand and palladium (π-cinnamyl) chloride dimer as the palladium source. ([(11)C]Methyl)raclopride was prepared by a previously published method. In the PET study, two female cynomolgus monkeys were used under gas anesthesia of sevoflurane. A dynamic PET measurement was performed for 63 min with an HRRT PET camera after intravenous injection of ([(11)C]carbonyl)raclopride and ([(11)C]methyl)raclopride, respectively, during the same day. The order of injection of the two PET radioligands was changed between the two monkeys. The venous blood sample for measurement of protein binding was taken 3 min prior to the PET scan. Binding potential (BPND) of the putamen and caudate was calculated with SRTM using the cerebellum as a reference region. RESULTS The target compound ([(11)C]carbonyl)raclopride was obtained with 50 ± 5% decay corrected radiochemical yield and 95% radiochemical purity. The trapping efficiency (TE) of [(11)C]carbon monoxide was 65 ± 5% and the specific radioactivity of the final product was 34 ± 1 GBq/μmol after a 50 min of synthesis time. The radiochemical yield of ([(11)C]methyl)raclopride was in the same range as published previously i. e. 50-60% and specific radioactivity of those two batches which were used in the present PET study were 192 GBq/μmol and 638 GBq/μmol respectively after a synthesis time of 32 min. In monkey PET studies, the percentage difference of BPND in putamen was <3% and that in caudate was <9% for the two radioligands. The plasma protein binding was 86.2 ± 0.3% and 85.7 ± 0.6% for ([(11)C]carbonyl)raclopride and ([(11)C]methyl)raclopride, respectively. The radiometabolite pattern was similar for both radioligands. CONCLUSION Raclopride was (11)C-labeled at the carbonyl position using a palladium-mediated [(11)C]carbonylation reaction. A comparison between ([(11)C]carbonyl)raclopride and ([(11)C]methyl)raclopride with regard to quantitative PET outcome measurements, metabolism of radioligands and protein binding in monkey was performed. The monkey PET study with ([(11)C]carbonyl)raclopride showed similar results as for ([(11)C]methyl)raclopride. The PET studies were performed on 2 subjects.
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Affiliation(s)
- Obaidur Rahman
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden; Bencar AB, Dag Hammarskjöldsväg 34B, 75183 Uppsala, Sweden; Department of Chemistry-BMC, Uppsala University, Husargatan 3, 75237 Uppsala, Sweden
| | - Akihiro Takano
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden
| | - Nahid Amini
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden
| | - Kenneth Dahl
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden
| | - Naoki Kanegawa
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden
| | - Bengt Långström
- Bencar AB, Dag Hammarskjöldsväg 34B, 75183 Uppsala, Sweden; Department of Chemistry-BMC, Uppsala University, Husargatan 3, 75237 Uppsala, Sweden
| | - Lars Farde
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska University Hospital, R5:U1, 17176 Stockholm, Sweden; Department of Chemistry-BMC, Uppsala University, Husargatan 3, 75237 Uppsala, Sweden
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Takano A, Stepanov V, Gulyás B, Nakao R, Amini N, Miura S, Kimura H, Taniguchi T, Halldin C. Evaluation of a novel PDE10A PET radioligand, [(11) C]T-773, in nonhuman primates: brain and whole body PET and brain autoradiography. Synapse 2015; 69:345-55. [PMID: 25892433 DOI: 10.1002/syn.21821] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 03/30/2015] [Accepted: 04/01/2015] [Indexed: 11/08/2022]
Abstract
Phosphodiesterase 10A (PDE10A) is considered to be a key target for the treatment of several neuropsychiatric diseases. The characteristics of [(11) C]T-773, a novel positron emission tomography (PET) radioligand with high binding affinity and selectivity for PDE10A, were evaluated in autoradiography and in nonhuman primate (NHP) PET. Brain PET measurements were performed under baseline conditions and after administration of a selective PDE10A inhibitor, MP-10. Total distribution volume (VT ) and binding potential (BPND ) were calculated using various kinetic models. Whole body PET measurements were performed to calculate the effective dose of [(11) C]T-773. Autoradiography studies in postmortem human and monkey brain sections showed high accumulation of [(11) C]T-773 in the striatum and substantia nigra which was blocked by MP-10. Brain PET showed high accumulation of [(11) C]T-773 in the striatum, and the data could be fitted using a two tissue compartment model. BPND was approximately 1.8 in the putamen when the cerebellum was used as the reference region. Approximately 70% of PDE10A binding was occupied by 1.8 mg/kg of MP-10. Whole body PET showed high accumulation of [(11) C]T-773 in the liver, kidney, heart, and brain in the initial phase. The radioligand was partly excreted via bile and the gastrointestinal tract, and partly excreted through the urinary tract. The calculated effective dose was 0.007 mSv/MBq. In conclusion, [(11) C]T-773 was demonstrated to be a promising PET radioligand for PDE10A with favorable brain kinetics. Dosimetry results support multiple PET measurements per person in human studies. Further research is required with [(11) C]T-773 in order to test the radioligand's potential clinical applications.
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Affiliation(s)
- Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Vladimir Stepanov
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Balázs Gulyás
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Ryuji Nakao
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Nahid Amini
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Shotaro Miura
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden.,CNS Drug Discovery Unit, Pharmaceutical Research Division, TAKEDA Pharmaceutical Company, Ltd., Fujisawa, Japan
| | - Haruhide Kimura
- CNS Drug Discovery Unit, Pharmaceutical Research Division, TAKEDA Pharmaceutical Company, Ltd., Fujisawa, Japan
| | - Takahiko Taniguchi
- CNS Drug Discovery Unit, Pharmaceutical Research Division, TAKEDA Pharmaceutical Company, Ltd., Fujisawa, Japan
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
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Stepanov V, Miura S, Takano A, Amini N, Nakao R, Hasui T, Nakashima K, Taniguchi T, Kimura H, Kuroita T, Halldin C. Development of a series of novel carbon-11 labeled PDE10A inhibitors. J Labelled Comp Radiopharm 2015; 58:202-8. [PMID: 25891816 DOI: 10.1002/jlcr.3284] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 12/22/2014] [Accepted: 03/04/2015] [Indexed: 11/11/2022]
Abstract
Phosphodiesterase 10A (PDE10A) is a member of the PDE family of enzymes that degrades cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Our aim was to label a series of structurally related PDE10A inhibitors with carbon-11 and evaluate them as potential positron emission tomography (PET) radioligands for PDE10A using nonhuman primates. The series consisted of seven compounds based on the 3-(1H-pyrazol-5-yl)pyridazin-4(1H)-one backbone. These compounds were selected from the initial larger library based on a number of parameters such as affinity, selectivity for hPDE10A in in vitro tests, lipophilicity, and on the results of multidrug resistance protein 1 (MDR1)-LLCPK1 and the parallel artificial membrane permeability assays. Seven radioligands (KIT-1, 3, 5, 6, 7, 9, and 12) were radiolabeled with carbon-11 employing O-methylation on the hydroxyl moiety using [(11)C]methyl triflate. In vivo examination of each radioligand was performed using PET in rhesus monkeys; analysis of radiometabolites in plasma also was conducted using HPLC. All seven radioligands were labeled with high (>90%) incorporation of [(11)C]methyl triflate into their appropriate precursors and with high specific radioactivity. Carbon-11 labeled KIT-5 and KIT-6 showed high accumulation in the striatum, consistent with the known anatomical distribution of PDE10A in brain, accompanied by fast washout and high specific binding ratio. In particular [(11)C]KIT-6, named [(11)C]T-773, is a promising PET tool for further examination of PDE10A in human brain.
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Affiliation(s)
- Vladimir Stepanov
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
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30
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Schou M, Varnäs K, Lundquist S, Nakao R, Amini N, Takano A, Finnema SJ, Halldin C, Farde L. Large Variation in Brain Exposure of Reference CNS Drugs: a PET Study in Nonhuman Primates. Int J Neuropsychopharmacol 2015; 18:pyv036. [PMID: 25813017 PMCID: PMC4648157 DOI: 10.1093/ijnp/pyv036] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 03/18/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Positron emission tomography microdosing of radiolabeled drugs allows for noninvasive studies of organ exposure in vivo. The aim of the present study was to examine and compare the brain exposure of 12 commercially available CNS drugs and one non-CNS drug. METHODS The drugs were radiolabeled with (11)C (t 1/2 = 20.4 minutes) and examined using a high resolution research tomograph. In cynomolgus monkeys, each drug was examined twice. In rhesus monkeys, a first positron emission tomography microdosing measurement was repeated after preadministration with unlabeled drug to examine potential dose-dependent effects on brain exposure. Partition coefficients between brain and plasma (KP) were calculated by dividing the AUC0-90 min for brain with that for plasma or by a compartmental analysis (VT). Unbound KP (KP u,u) was obtained by correction for the free fraction in brain and plasma. RESULTS After intravenous injection, the maximum radioactivity concentration (C max, %ID) in brain ranged from 0.01% to 6.2%. For 10 of the 12 CNS drugs, C max, %ID was >2%, indicating a preferential distribution to brain. A lower C max, %ID was observed for morphine, sulpiride, and verapamil. K P ranged from 0.002 (sulpiride) to 68 (sertraline) and 7 of 13 drugs had KP u,u close to unity. For morphine, sulpiride, and verapamil, K P u,u was <0.3, indicating impaired diffusion and/or active efflux. Brain exposure at microdosing agreed with pharmacological dosing conditions for the investigated drugs. CONCLUSIONS This study represents the largest positron emission tomography study on brain exposure of commercially available CNS drugs in nonhuman primates and may guide interpretation of positron emission tomography microdosing data for novel drug candidates.
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Affiliation(s)
- Magnus Schou
- AstraZeneca Translational Science Centre at Karolinska Institutet, Stockholm, Sweden (Drs Schou and Farde); Psychiatry Section, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden (Drs Varnäs, Lundquist, Nakao, Amini, Takano, Finnema, and Halldin); AstraZeneca, Innovative Medicines, CNS & Pain, Södertälje, Sweden (Dr Lundquist).
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31
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Hjorth S, Karlsson C, Jucaite A, Varnäs K, Wählby Hamrén U, Johnström P, Gulyás B, Donohue SR, Pike VW, Halldin C, Farde L. A PET study comparing receptor occupancy by five selective cannabinoid 1 receptor antagonists in non-human primates. Neuropharmacology 2015; 101:519-30. [PMID: 25791528 DOI: 10.1016/j.neuropharm.2015.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/05/2015] [Accepted: 03/07/2015] [Indexed: 01/14/2023]
Abstract
There is a medical need for safe and efficacious anti-obesity drugs with acceptable side effect profiles. To mitigate the challenge posed by translating target interaction across species and balancing beneficial vs. adverse effects, a positron emission tomography (PET) approach could help guide clinical dose optimization. Thus, as part of a compound differentiation effort, three novel selective CB1 receptor (CB1R) antagonists, developed by AstraZeneca (AZ) for the treatment of obesity, were compared with two clinically tested reference compounds, rimonabant and taranabant, with regard to receptor occupancy relative to dose and exposure. A total of 42 PET measurements were performed in 6 non-human primates using the novel CB1R antagonist radioligand [(11)C]SD5024. The AZ CB1R antagonists bound in a saturable manner to brain CB1R with in vivo affinities similar to that of rimonabant and taranabant, compounds with proven weight loss efficacy in clinical trials. Interestingly, it was found that exposures corresponding to those needed for optimal clinical efficacy of rimonabant and taranabant resulted in a CB1R occupancy typically around ∼20-30%, thus much lower than what would be expected for classical G-protein coupled receptor (GPCR) antagonists in other therapeutic contexts. These findings are also discussed in relation to emerging literature on the potential usefulness of 'neutral' vs. 'classical' CB1R (inverse agonist) antagonists. The study additionally highlighted the usefulness of the radioligand [(11)C]SD5024 as a specific tracer for CB1R in the primate brain, though an arterial input function would ideally be required in future studies to further assure accurate quantitative analysis of specific binding.
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Affiliation(s)
- Stephan Hjorth
- Biosciences, CVMD Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden
| | - Cecilia Karlsson
- CVMD Translational Medicine Unit, Early Clinical Development, Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden.
| | - Aurelija Jucaite
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Katarina Varnäs
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ulrika Wählby Hamrén
- Quantitative Clinical Pharmacology, Early Clinical Development, Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden
| | - Peter Johnström
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Balázs Gulyás
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sean R Donohue
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Christer Halldin
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Lars Farde
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Johnström P, Bergman L, Varnäs K, Malmquist J, Halldin C, Farde L. Development of rapid multistep carbon-11 radiosynthesis of the myeloperoxidase inhibitor AZD3241 to assess brain exposure by PET microdosing. Nucl Med Biol 2015; 42:555-60. [PMID: 25726760 DOI: 10.1016/j.nucmedbio.2015.02.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/16/2015] [Accepted: 02/03/2015] [Indexed: 01/10/2023]
Abstract
INTRODUCTION The myeloperoxidase inhibitor AZD3241 has been selected as a candidate drug currently being developed to delay progression in patients with neurodegenerative brain disorders. Part of the decision tree for translation of AZD3241 into clinical studies included the need for assessment of brain exposure in non-human primates by PET microdosing. For that purpose a rapid multistep method for (11)C-labeling of AZD3241 was developed. METHODS AZD3241 was labeled in the thio-carbonyl position starting from [(11)C]potassium cyanide in a 4-step procedure using microwave assisted heating. In the first step [(11)C]potassium cyanide was converted to [(11)C]potassium thiocyanate followed by reaction with benzoyl chloride to yield benzoyl [(11)C]isothiocyanate. The benzoyl [(11)C]isothiocyanate was subsequently reacted with the precursor ethyl 3-(2-isopropoxyethylamino)-1H-pyrrole-2-carboxylate and the formed intermediate underwent a base catalyzed cyclization to obtain [(11)C]AZD3241 in the final step. To assess [(11)C]AZD3241 brain exposure PET measurements were performed in three cynomolgus monkeys. RESULTS [(11)C]AZD3241 was produced in good and reproducible radiochemical yield 710 ± 294 MBq (mean ± SD, n = 7). Total time of synthesis was 60 min from end of bombardment. The specific radioactivity was 9 ± 4GBq/μmol and the radiochemical purity was >98%. Following iv administration of [(11)C]AZD3241 there was a rapid presence of radioactivity in brain in each of the three monkeys. The distribution of [(11)C]AZD3241 to brain was fast and a Cmax of 1.9 to 2.6% of the injected radioactivity was observed within 1.5 min. [(11)C]AZD3241 was homogeneously distributed in brain. CONCLUSION The MPO inhibitor AZD3241 was successfully labeled with carbon-11 in a challenging 4-step procedure in good radiochemical yield allowing PET microdosing studies in cynomolgus monkey. [(11)C]AZD3241 rapidly entered brain and confirmed adequate brain exposure to support translation of AZD3241 to phase 2a studies in patients.
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Affiliation(s)
- Peter Johnström
- AstraZeneca Translational Science Centre at Karolinska Institutet, Stockholm, Sweden; Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research and Education, Stockholm, Sweden.
| | - Linda Bergman
- Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research and Education, Stockholm, Sweden
| | - Katarina Varnäs
- Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research and Education, Stockholm, Sweden
| | - Jonas Malmquist
- Isotope Chemistry, Screening and Profiling Global DMPK IM, AstraZeneca, Research & Development Innovative Medicines, Södertälje, Sweden
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research and Education, Stockholm, Sweden
| | - Lars Farde
- AstraZeneca Translational Science Centre at Karolinska Institutet, Stockholm, Sweden; Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research and Education, Stockholm, Sweden
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Bioactive benzofuran derivatives: An insight on lead developments, radioligands and advances of the last decade. Eur J Med Chem 2015; 97:356-76. [PMID: 25703339 DOI: 10.1016/j.ejmech.2015.01.021] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 12/19/2014] [Accepted: 01/10/2015] [Indexed: 02/08/2023]
Abstract
Benzofuran core is a highly versatile, presents in many important natural products and natural drugs. Many benzofuran containing synthetic drugs and clinical candidates have been derived from natural products. The present review will provide an insight on lead design-developments of the decade, clinical candidates and PET tracer radio-ligands containing benzofuran core along with brief target biology. Brief of the all approved drugs containing benzofuran core also have been enclosed. Main therapeutic areas covered are Cancer, Neurological disorders including anti-psychotic agent and diabetes.
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Harada A, Suzuki K, Miura S, Hasui T, Kamiguchi N, Ishii T, Taniguchi T, Kuroita T, Takano A, Stepanov V, Halldin C, Kimura H. Characterization of the binding properties of T-773 as a PET radioligand for phosphodiesterase 10A. Nucl Med Biol 2014; 42:146-54. [PMID: 25451212 DOI: 10.1016/j.nucmedbio.2014.09.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 09/02/2014] [Accepted: 09/04/2014] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Phosphodiesterase 10A (PDE10A) is a dual-substrate PDE that hydrolyzes both cAMP and cGMP and is selectively expressed in striatal medium spiny neurons. Recent studies have suggested that PDE10A inhibition is a novel approach for the treatment of disorders such as schizophrenia and Huntington's disease. A positron emission tomography (PET) occupancy study can provide useful information for the development of PDE10A inhibitors. We discovered T-773 as a candidate PET radioligand for PDE10A and investigated its properties by in vitro autoradiography and a PET study in a monkey. METHODS Profiling of T-773 as a PET radioligand for PDE10A was conducted by in vitro enzyme inhibitory assay, in vitro autoradiography, and PET study in a monkey. RESULTS T-773 showed a high binding affinity and selectivity for human recombinant PDE10A2 in vitro; the IC50 value in an enzyme inhibitory assay was 0.77nmol/L, and selectivity over other PDEs was more than 2500-fold. In autoradiography studies using mouse, rat, monkey, or human brain sections, radiolabeled T-773 selectively accumulated in the striatum. This selective accumulation was not observed in the brain sections of Pde10a-KO mice. The binding of [(3)H]T-773 to PDE10A in rat brain sections was competitively inhibited by MP-10, a selective PDE10A inhibitor. In rat brain sections, [(3)H]T-773 bound to a single high affinity site of PDE10A with Kd values of 12.2±2.2 and 4.7±1.2nmol/L in the caudate-putamen and nucleus accumbens, respectively. In a monkey PET study, [(11)C]T-773 showed good brain penetration and striatum-selective accumulation. CONCLUSION These results suggest that [(11)C]T-773 is a potential PET radioligand for PDE10A.
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Affiliation(s)
- Akina Harada
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Kazunori Suzuki
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Shotaro Miura
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Tomoaki Hasui
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Naomi Kamiguchi
- Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Tsuyoshi Ishii
- Biomolecular Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Takahiko Taniguchi
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Takanobu Kuroita
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Akihiro Takano
- Center for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Vladimir Stepanov
- Center for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Christer Halldin
- Center for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Haruhide Kimura
- CNS Drug Discovery Unit, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Fujisawa, Japan.
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Development of (18)F-labeled radiotracers for neuroreceptor imaging with positron emission tomography. Neurosci Bull 2014; 30:777-811. [PMID: 25172118 DOI: 10.1007/s12264-014-1460-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/02/2014] [Indexed: 12/14/2022] Open
Abstract
Positron emission tomography (PET) is an in vivo molecular imaging tool which is widely used in nuclear medicine for early diagnosis and treatment follow-up of many brain diseases. PET uses biomolecules as probes which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiotracers. Fluorine-18 is a radionuclide routinely used in the radiolabeling of neuroreceptor ligands for PET because of its favorable half-life of 109.8 min. The delivery of such radiotracers into the brain provides images of transport, metabolic, and neurotransmission processes on the molecular level. After a short introduction into the principles of PET, this review mainly focuses on the strategy of radiotracer development bridging from basic science to biomedical application. Successful radiotracer design as described here provides molecular probes which not only are useful for imaging of human brain diseases, but also allow molecular neuroreceptor imaging studies in various small-animal models of disease, including genetically-engineered animals. Furthermore, they provide a powerful tool for in vivo pharmacology during the process of pre-clinical drug development to identify new drug targets, to investigate pathophysiology, to discover potential drug candidates, and to evaluate the pharmacokinetics and pharmacodynamics of drugs in vivo.
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Gourand F, Emond P, Bergström JP, Takano A, Gulyás B, Guilloteau D, Barré L, Halldin C. A radiometabolite study of the serotonin transporter PET radioligand [(11)C]MADAM. Nucl Med Biol 2014; 41:501-6. [PMID: 24857865 DOI: 10.1016/j.nucmedbio.2014.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 11/15/2022]
Abstract
INTRODUCTION (11)C]MADAM is a radioligand suitable for PET studies of the serotonin transporter (SERT). Metabolite analysis in human and non-human plasma samples using HPLC separation has shown that [(11)C]MADAM was rapidly metabolized. A possible metabolic pathway is the S-oxidation which could lead to SOMADAM and SO2MADAM. In vitro evaluation of these two potential metabolites has shown that SOMADAM exhibited a good affinity for SERT and a good selectivity for SERT over NET and DAT. METHODS Comparative PET imaging studies in non-human primate brain with [(11)C]MADAM and [(11)C]SOMADAM were carried out, and plasma samples were analyzed using reverse phase HPLC. We have explored the metabolism of [(11)C]MADAM in rat brain with a view to understand its possible interference for brain imaging with PET. RESULTS PET imaging studies in non-human primate brain using [(11)C]SOMADAM indicated that this tracer does not bind with high amounts to brain regions known to be rich in SERT. The fraction of [(11)C]SOMADAM in non-human primate plasma was approximately 5% at 4min and 1% at 15min after [(11)C]MADAM injection. HPLC analysis of brain sample after [(11)C]MADAM injection to rats demonstrated that [(11)C]SOMADAM was not detected in the brain. CONCLUSIONS (11)C]SOMADAM is not superior over [(11)C]MADAM as a SERT PET radioligand. Nevertheless, [(11)C]SOMADAM has been identified as a minor labeled metabolite of [(11)C]MADAM measured in monkey plasma. [(11)C]SOMADAM was not detected in rat brain.
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Affiliation(s)
- F Gourand
- CEA, DSV/I2BM, LDM-TEP Group, GIP Cyceron, Bd Henri Becquerel, BP 5229, 14074 Caen Cedex, France; Université de Caen Basse-Normandie, Caen, France; CNRS, UMR ISTCT 6301, LDM-TEP Group, GIP Cyceron, Caen, France; Karolinska Institutet, Department of Clinical Neuroscience, Section of Psychiatry, SE-171 76 Stockholm, Sweden.
| | - P Emond
- INSERM U930- Université François Rabelais de Tours, CHRU de Tours, Hopital Bretonneau, 2 boulevard Tonnellé, 37044 Tours, France
| | - J P Bergström
- Karolinska Institutet, Department of Clinical Neuroscience, Section of Psychiatry, SE-171 76 Stockholm, Sweden
| | - A Takano
- Karolinska Institutet, Department of Clinical Neuroscience, Section of Psychiatry, SE-171 76 Stockholm, Sweden
| | - B Gulyás
- Karolinska Institutet, Department of Clinical Neuroscience, Section of Psychiatry, SE-171 76 Stockholm, Sweden
| | - D Guilloteau
- INSERM U930- Université François Rabelais de Tours, CHRU de Tours, Hopital Bretonneau, 2 boulevard Tonnellé, 37044 Tours, France
| | - L Barré
- CEA, DSV/I2BM, LDM-TEP Group, GIP Cyceron, Bd Henri Becquerel, BP 5229, 14074 Caen Cedex, France; Université de Caen Basse-Normandie, Caen, France; CNRS, UMR ISTCT 6301, LDM-TEP Group, GIP Cyceron, Caen, France
| | - C Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Section of Psychiatry, SE-171 76 Stockholm, Sweden
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Characterization of [11C]Cimbi-36 as an agonist PET radioligand for the 5-HT2A and 5-HT2C receptors in the nonhuman primate brain. Neuroimage 2014; 84:342-53. [DOI: 10.1016/j.neuroimage.2013.08.035] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/12/2013] [Accepted: 08/15/2013] [Indexed: 11/18/2022] Open
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Low brain CB1 receptor occupancy by a second generation CB1 receptor antagonist TM38837 in comparison with rimonabant in nonhuman primates: A PET study. Synapse 2013; 68:89-97. [DOI: 10.1002/syn.21721] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/01/2013] [Accepted: 10/27/2013] [Indexed: 01/26/2023]
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Nag S, Lehmann L, Kettschau G, Toth M, Heinrich T, Thiele A, Varrone A, Halldin C. Development of a novel fluorine-18 labeled deuterated fluororasagiline ([18F]fluororasagiline-D2) radioligand for PET studies of monoamino oxidase B (MAO-B). Bioorg Med Chem 2013; 21:6634-41. [DOI: 10.1016/j.bmc.2013.08.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 07/03/2013] [Accepted: 08/07/2013] [Indexed: 11/16/2022]
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Airaksinen AJ, Finnema SJ, Balle T, Varnäs K, Bang-Andersen B, Gulyás B, Farde L, Halldin C. Radiosynthesis and evaluation of new α1-adrenoceptor antagonists as PET radioligands for brain imaging. Nucl Med Biol 2013; 40:747-54. [PMID: 23810488 DOI: 10.1016/j.nucmedbio.2013.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/06/2013] [Accepted: 05/18/2013] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Evaluation of the α1-adrenoceptors in relation to brain pathophysiology and drug treatment has been hindered by lack of α1-adrenoceptor specific radioligands with sufficient brain exposure. Our aim was to develop an α1-adrenoceptor specific PET radioligand for brain imaging. METHODS Two sertindole analogues 1-(4-fluorophenyl)-5-(1-methyl-1H-1,2,4-triazol-3-yl)-3-(1-[(11)C]methylpiperidin-4-yl)-1H-indole [(11)C]3 and 1-(4-fluorophenyl)-3-(1-[(11)C]methylpiperidin-4-yl)-5-(pyrimidin-5-yl)-1H-indole ([(11)C]Lu AA27122) [(11)C]4 were synthesized and evaluated as α1-adrenoceptor PET radioligands in cynomolgus monkey. Compounds 3 and 4 were selected due to their promising in vitro preclinical profile; high affinity and selectivity for the α1-adrenoceptor, favourable blood brain barrier permeability rates in Caco-2 monolayers and promising brain tissue/plasma ratio, assessed by equilibrium dialysis of free fraction in plasma and brain homogenate. RESULTS Compounds [(11)C]3 and [(11)C]4 were synthesized from their desmethyl piperidine precursors with high specific radioactivity (>370 GBq/μmol) using [(11)C]methyl iodide. The 1,2,4-triazole analogue [(11)C]3 exhibited poor brain uptake, but the corresponding pyrimidyl analogue [(11)C]4 exhibited high brain exposure and binding in α1-adrenoceptor rich brain regions. However, the binding could not be inhibited by pretreatment with prazosin (0.1 mg/kg and 0.3 mg/kg). The results were extended by autoradiography of [(11)C]4 binding in human brain sections and competition with antagonists from different structural families, revealing that only a minor portion of the observed binding of [(11)C]4 in brain was α1-adrenoceptor specific. CONCLUSION Though [(11)C]3 and [(11)C]4 proved not suitable as PET radioligands, the study provided further understanding of structural features influencing brain exposure of the chemical class of compounds related to the antipsychotic drug sertindole. It provided valuable insight in the delicacy of blood brain barrier penetration for structurally related compounds and underlines the importance for improved protocols for evaluation of brain penetration of future PET ligands.
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Affiliation(s)
- Anu J Airaksinen
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Karolinska Hospital, S-17176 Stockholm, Sweden.
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Palladium mediated ¹¹C-cyanation and characterization in the non-human primate brain of the novel mGluR5 radioligand [¹¹C]AZD9272. Nucl Med Biol 2013; 40:547-53. [PMID: 23541825 DOI: 10.1016/j.nucmedbio.2012.12.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 12/13/2012] [Accepted: 12/29/2012] [Indexed: 11/22/2022]
Abstract
INTRODUCTION The aims of the present positron emission tomography (PET) study were to set up a system for (11)C-cyanation labeling of the selective mGluR5-antagonist [(11)C]AZD9272 and to perform the first in vivo characterization of [(11)C]AZD9272 binding in cynomolgus monkeys. METHODS [(11)C]AZD9272 was labeled using palladium mediated (11)C-cyanation. Altogether seven PET measurements were performed in three cynomolgus monkeys including baseline and co-injection experiments with unlabelled AZD9272 (0.04 and 0.4 mg/kg). Radiometabolites in plasma were measured using HPLC. RESULTS [(11)C]AZD9272 was prepared in over 50% incorporation yield from hydrogen [(11)C]cyanide in a total synthesis time of 45-50 min. The radiochemical purity of the radioligand in its final formulation was high (>99%) and the mean specific radioactivity was 47 GBq/ μmol (1278 Ci/mmol, n=7) calculated at end of bombardment (EOB). In the baseline measurements 10% of the total injected radioactivity was present in monkey brain at five minutes after i.v. injection. The radioactivity concentration was high in the caudate, cingulate gyrus and thalamus whereas it was moderate in the temporal cortex and lower for the cerebellum. After co-injection with cold AZD9272 the binding of [(11)C]AZD9272 was reduced in a dose-dependent fashion. Analysis of radiometabolites showed relatively slow metabolism and resulted only in hydrophilic radiometabolites. CONCLUSION A fast and efficient method was developed to label AZD9272 with (11)C. PET-examination in Cynomolgus monkeys showed that [(11)C]AZD9272 entered the brain to a high extent, that binding was saturable and that the regional radioactivity pattern was in accordance with the known distribution of mGluR5. The results support further examination of [(11)C]AZD9272 binding in human subjects.
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SERT and NET occupancy by venlafaxine and milnacipran in nonhuman primates: a PET study. Psychopharmacology (Berl) 2013; 226:147-53. [PMID: 23090625 DOI: 10.1007/s00213-012-2901-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Serotonin and norepinephrine reuptake inhibitors (SNRIs) are antidepressants which have high affinity to both serotonin transporter (SERT) and norepinephrine transporter (NET). In studies in vitro, SNRIs have been reported to show a large variability in the affinity ratio between SERT and NET. For instance, the reported affinity ratio is about 30 for venlafaxine and 1.6 for milnacipran. In this study in nonhuman primates, we aimed to investigate the relationship between SERT and NET affinity by measuring the in vivo occupancy at both transporters of venlafaxine and milnacipran. METHODS PET measurements with [(11)C]MADAM and [(18)F]FMeNER-D(2) were performed in two female cynomolgus monkeys at baseline and after pretreatment with venlafaxine and milnacipran, respectively. Relationships between dose, plasma concentration, and transporter occupancy were evaluated by saturation analysis using a hyperbolic function. Binding affinity (Kd(plasma)) was expressed by the dose or plasma concentration at which 50 % of the transporter was occupied. RESULTS SERT and NET occupancy by venlafaxine and milnacipran increased in a dose and plasma concentration-dependent manner. The Kd(plasma) ratio of SERT to NET was 1.9 for venlafaxine and 0.6 for milnacipran. CONCLUSIONS In this nonhuman primate PET study, the affinity in vivo for SERT and NET, respectively, was shown to be at a similar level for venlafaxine and milnacipran. Both drugs were found to produce balanced inhibition of SERT and NET binding. This observation is not consistent with previous in vitro binding data and illustrates the need to characterize antidepressants at in vivo condition.
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Schou M, Varnäs K, Jucaite A, Gulyás B, Halldin C, Farde L. Radiolabeling of the cannabinoid receptor agonist AZD1940 with carbon-11 and PET microdosing in non-human primate. Nucl Med Biol 2013; 40:410-4. [PMID: 23352602 DOI: 10.1016/j.nucmedbio.2012.10.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 08/28/2012] [Accepted: 10/30/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION N-(2-tert-butyl-1-((4,4-difluorocyclohexyl)methyl)-1H-benzo[d]imidazol-5-yl)ethanesulfonamide (AZD1940) is a candidate drug for treatment of neuropathic pain. As part of the preclinical evaluation of AZD1940, a microdosing study with positron emission tomography (PET) was conducted to assess brain exposure. METHODS AZD1940 was radiolabeled with carbon-11 in the benzimidazole moiety. The radioactive precursor, lithium [(11)C]pivalate was obtained via (11)C-carboxylation of tert-butyl lithium. The target compound, [(11)C]AZD1940, was in turn obtained by the microwave assisted reaction between lithium [(11)C]pivalate and the o-phenylene diamine analog of AZD1940 (N-(3-amino-4-((4,4-difluorocyclohexyl)methylamino)phenyl)ethanesulfonamide) in neat phosphorous oxychloride. A brain PET measurement was performed in cynomolgus monkey. RESULTS The overall radiochemical yield of final formulated radiochemically pure (>99%) [(11)C]AZD1940 was 0.4% (uncorrected for decay) and the specific radioactivity was 13GBq/μmol at time of administration (58min after end of bombardment). After intravenous injection to cynomolgus monkey, the maximum concentration of radioactivity detected in the brain region of interest was 0.7% of the total injected radioactivity. The regional distribution of radioactivity within brain was homogenous. CONCLUSIONS AZD1940 was radiolabelled with carbon-11 and its brain exposure, assessed using PET, was relatively low in comparison to peripheral organ exposure.
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Affiliation(s)
- Magnus Schou
- AstraZeneca Translational Sciences Centre, PET CoE, Dept of Clinical Neuroscience, Karolinska Institutet, Karolinska Hospital, SE-17176 Stockholm, Sweden.
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Synthesis and biological evaluation of novel propargyl amines as potential fluorine-18 labeled radioligands for detection of MAO-B activity. Bioorg Med Chem 2013; 21:186-95. [DOI: 10.1016/j.bmc.2012.10.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 10/20/2012] [Accepted: 10/25/2012] [Indexed: 10/27/2022]
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Nag S, Lehmann L, Kettschau G, Heinrich T, Thiele A, Varrone A, Gulyas B, Halldin C. Synthesis and evaluation of [18F]fluororasagiline, a novel positron emission tomography (PET) radioligand for monoamine oxidase B (MAO-B). Bioorg Med Chem 2012; 20:3065-71. [DOI: 10.1016/j.bmc.2012.02.056] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 02/23/2012] [Accepted: 02/25/2012] [Indexed: 11/24/2022]
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Finnema SJ, Varrone A, Hwang TJ, Halldin C, Farde L. Confirmation of fenfluramine effect on 5-HT(1B) receptor binding of [(11)C]AZ10419369 using an equilibrium approach. J Cereb Blood Flow Metab 2012; 32:685-95. [PMID: 22167236 PMCID: PMC3318146 DOI: 10.1038/jcbfm.2011.172] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Assessment of serotonin release in the living brain with positron emission tomography (PET) may have been hampered by the lack of suitable radioligands. We previously reported that fenfluramine caused a dose-dependent reduction in specific binding in monkeys using a classical displacement paradigm with bolus administration of [(11)C]AZ10419369. The aim of this study was to confirm our previous findings using an equilibrium approach in monkey. A total of 24 PET measurements were conducted using a bolus infusion protocol of [(11)C]AZ10419369 in three cynomolgus monkeys. Initial PET measurements were performed to assess suitable K(bol) values. The fenfluramine effect on [(11)C]AZ10419369 binding was evaluated in a displacement and pretreatment paradigm. The effect of fenfluramine on [(11)C]AZ10419369 binding potential (BP(ND)) was dose-dependent in the displacement paradigm and confirmed in the pretreatment paradigm. After pretreatment administration of fenfluramine (5.0 mg/kg), the mean BP(ND) of the occipital cortex decreased by 39%, from 1.38±0.04 to 0.84±0.09. This study confirms that the new 5-HT(1B) receptor radioligand [(11)C]AZ10419369 is sensitive to fenfluramine-induced changes in endogenous serotonin levels in vivo. The more advanced methodology is suitable for exploring the sensitivity limit to serotonin release as measured using [(11)C]AZ10419369 and PET.
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Affiliation(s)
- Sjoerd J Finnema
- Psychiatry Section, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Nag S, Varrone A, Tóth M, Thiele A, Kettschau G, Heinrich T, Lehmann L, Halldin C. In vivo evaluation in cynomolgus monkey brain and metabolism of [¹⁸F]fluorodeprenyl: a new MAO-B pet radioligand. Synapse 2011; 66:323-30. [PMID: 22124971 DOI: 10.1002/syn.21514] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 10/28/2011] [Indexed: 11/11/2022]
Abstract
In this study, we evaluated the in vivo characteristics of a new monoamine oxidase type B (MAO-B) radioligand, [¹⁸F]fluorodeprenyl, by positron emission tomography (PET) in two cynomolgus monkeys. The brain uptake of [¹⁸F]fluorodeprenyl was more than 7% (600% SUV) of the total injected radioactivity and similar to that of [¹¹C]deprenyl, an established MAO-B radioligand. The highest uptake was observed in the striatum, one of the MAO-B-rich regions, with a peak at approximately 2-3 min after injection, followed by lower uptake in the thalamus and the cortex and lowest uptake in the cerebellum. Brain uptake of [¹⁸F]fluorodeprenyl was largely inhibited by preadministration of the MAO-B inhibitor, L-deprenyl, whereas clorgyline, a MAO Type A blocker, had no significant inhibitory effect, thus demonstrating selectivity for MAO-B. [¹⁸F]Fluorodeprenyl showed relatively slow metabolism with the presence of two radiometabolite peaks with similar retention time as the labeled metabolites of [¹¹C]deprenyl. These results suggest that [¹⁸F]fluorodeprenyl is a potential PET radioligand for visualization of MAO-B activity.
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Affiliation(s)
- Sangram Nag
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-17176 Stockholm, Sweden.
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Seneca N, Finnema SJ, Laszlovszky I, Kiss B, Horváth A, Pásztor G, Kapás M, Gyertyán I, Farkas S, Innis RB, Halldin C, Gulyás B. Occupancy of dopamine D₂ and D₃ and serotonin 5-HT₁A receptors by the novel antipsychotic drug candidate, cariprazine (RGH-188), in monkey brain measured using positron emission tomography. Psychopharmacology (Berl) 2011; 218:579-87. [PMID: 21625907 PMCID: PMC3210913 DOI: 10.1007/s00213-011-2343-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/04/2011] [Indexed: 12/19/2022]
Abstract
RATIONALE Cariprazine is a novel antipsychotic drug candidate that exhibits high selectivity and affinity to dopamine D(3) and D(2) receptors and moderate affinity to serotonin 5-HT(1A) receptors. Targeting receptors other than D(2) may provide a therapeutic benefit for both positive and negative symptoms associated with schizophrenia. Positron emission tomography (PET) can be used as a tool in drug development to assess the in vivo distribution and pharmacological properties of a drug. OBJECTIVES The objective of this study was to determine dopamine D(2)/D(3) and serotonin 5-HT(1A) receptor occupancy in monkey brain after the administration of cariprazine. METHODS We examined three monkeys using the following PET radioligands: [(11)C]MNPA (an agonist at D(2) and D(3) receptors), [(11)C]raclopride (an antagonist at D(2) and D(3) receptors), and [(11)C]WAY-100635 (an antagonist at 5-HT(1A) receptors). During each experimental day, the first PET measurement was a baseline study, the second after a low dose of cariprazine, and the third after the administration of a high dose. RESULTS We found that cariprazine occupied D(2)/D(3) receptors in a dose-dependent and saturable manner, with the lowest dose occupying ~5% of receptors and the highest dose showing more than 90% occupancy. 5-HT(1A) receptor occupancy was considerably lower compared with D(2)/D(3) occupancy at the same doses, with a maximal value of ~30% for the raphe nuclei. CONCLUSIONS We conclude that cariprazine binds preferentially to dopamine D(2)/D(3) rather than to serotonin 5-HT(1A) receptors in monkey brain. These findings can be used to guide the selection of cariprazine dosing in humans.
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Affiliation(s)
- Nicholas Seneca
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden,Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Sjoerd J. Finnema
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden
| | | | - Béla Kiss
- Gedeon Richter Ltd., Budapest 1103, Hungary
| | | | | | | | | | | | - Robert B. Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Balás Gulyás
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden
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Varrone A, Stepanov V, Nakao R, Tóth M, Gulyás B, Emond P, Deloye JB, Vercouillie J, Stabin MG, Jonsson C, Guilloteau D, Halldin C. Imaging of the Striatal and Extrastriatal Dopamine Transporter with 18F-LBT-999: Quantification, Biodistribution, and Radiation Dosimetry in Nonhuman Primates. J Nucl Med 2011; 52:1313-21. [DOI: 10.2967/jnumed.111.089953] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Takano A, Nag S, Gulyás B, Halldin C, Farde L. NET occupancy by clomipramine and its active metabolite, desmethylclomipramine, in non-human primates in vivo. Psychopharmacology (Berl) 2011; 216:279-86. [PMID: 21336575 DOI: 10.1007/s00213-011-2212-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 01/28/2011] [Indexed: 11/29/2022]
Abstract
RATIONALE Norepinephrine transporter (NET) is one of the key targets for antidepressants such as combined serotonin and norepinephrine reuptake inhibitors as well as some of the tricyclic antidepressants. Clomipramine, a tricyclic antidepressant, has been reported to have an active metabolite, desmethylclomipramine, which has high affinity for NET in vitro. However, the NET occupancy of clomipramine and desmethylclomipramine has not fully been evaluated in vivo. OBJECTIVES In this positron emission tomography (PET) study, we investigate NET occupancy by clomipramine and desmethylclomipramine, respectively, in non-human primates with a selective radioligand for NET, (S,S)-[(18)F]FMeNER-D(2). METHODS PET measurements were performed with (S,S)-[(18)F]FMeNER-D(2) at baseline and after the intravenous administration of clomipramine and desmethylclomipramine, respectively. NET binding was calculated with the simplified reference tissue model using the caudate as reference region. NET occupancy was calculated as the difference in NET binding between the baseline and pretreatment condition. The relationship between NET occupancy and dose/plasma concentration was evaluated using hyperbolic functions. RESULTS NET occupancy by both clomipramine and desmethylclomipramine increased in a dose and plasma concentration-dependent manner. The mean Kd values, expressed as the dose or plasma concentration at which 50% of NET was occupied, were 0.44 mg/kg and 24.5 ng/ml for clomipramine and 0.11 mg/kg and 4.4 ng/ml for desmethylclomipramine. CONCLUSIONS Not only desmethylclomipramine but also clomipramine was demonstrated to occupy NET in the non-human primate in vivo. It can thus be assumed that NET occupancy during clinical treatment with clomipramine is a combined effect of unchanged clomipramine and its main metabolite desmethylclomipramine.
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Affiliation(s)
- Akihiro Takano
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, 171 76, Stockholm, Sweden.
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