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Sah BR, Sommerauer M, Mu L, Gonzalez GP, Geistlich S, Treyer V, Schibli R, Buck A, Warnock G, Ametamey SM. Radiation dosimetry of [ 18F]-PSS232-a PET radioligand for imaging mGlu5 receptors in humans. EJNMMI Res 2019; 9:56. [PMID: 31240594 PMCID: PMC6593000 DOI: 10.1186/s13550-019-0522-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/28/2019] [Indexed: 11/25/2022] Open
Abstract
Purpose (E)-3-(pyridin-2-ylethynyl)cyclohex-2-enone O-(3-(2-[18F]-fluoroethoxy)propyl) oxime ([18F]-PSS232) is a new PET tracer for imaging of metabotropic glutamate receptor subtype 5 (mGlu5), and has shown promising results in rodents and humans. The aim of this study was to estimate the radiation dosimetry and biodistribution in humans, to assess dose-limiting organs, and to demonstrate safety and tolerability of [18F]-PSS232 in healthy volunteers. Methods PET/CT scans of six healthy male volunteers (mean age 23.5 ± 1.7; 21–26 years) were obtained after intravenous administration of 243 ± 3 MBq of [18F]-PSS232. Serial whole-body (vertex to mid-thigh) PET scans were assessed at ten time points, up to 90 min after tracer injection. Calculation of tracer kinetics and cumulated organ activities were performed using PMOD 3.7 software. Dosimetry estimates were calculated using the OLINDA/EXM software. Results Injection of [18F]-PSS232 was safe and well tolerated. Organs with highest absorbed doses were the gallbladder wall (0.2295 mGy/MBq), liver (0.0547 mGy/MBq), and the small intestine (0.0643 mGy/MBq). Mean effective dose was 3.72 ± 0.12 mSv/volunteer (range 3.61–3.96 mSv; 0.0153 mSv/MBq). Conclusion [18F]-PSS232, a novel [18F]-labeled mGlu5 tracer, showed favorable dosimetry values. Additionally, the tracer was safe and well tolerated.
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Affiliation(s)
- Bert-Ram Sah
- Department of Nuclear Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland.,Department of Diagnostic, Interventional, and Pediatric Radiology, Inselspital, University of Bern, Bern, Switzerland
| | - Michael Sommerauer
- Department of Nuclear Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland.,Department of Neurology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Linjing Mu
- Department of Nuclear Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Gloria Pla Gonzalez
- Radiopharmaceutical Science, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Susanne Geistlich
- Radiopharmaceutical Science, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Valerie Treyer
- Department of Nuclear Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Roger Schibli
- Radiopharmaceutical Science, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Geoffrey Warnock
- Department of Nuclear Medicine, University Hospital Zurich and University of Zurich, Zurich, Switzerland. .,PMOD Technologies LLC, Zurich, Switzerland.
| | - Simon M Ametamey
- Radiopharmaceutical Science, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
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Warnock G, Sommerauer M, Mu L, Pla Gonzalez G, Geistlich S, Treyer V, Schibli R, Buck A, Krämer SD, Ametamey SM. A first-in-man PET study of [ 18F]PSS232, a fluorinated ABP688 derivative for imaging metabotropic glutamate receptor subtype 5. Eur J Nucl Med Mol Imaging 2017; 45:1041-1051. [PMID: 29177707 DOI: 10.1007/s00259-017-3879-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 11/06/2017] [Indexed: 12/21/2022]
Abstract
PURPOSE Non-invasive imaging of metabotropic glutamate receptor 5 (mGlu5) in the brain using PET is of interest in e.g., anxiety, depression, and Parkinson's disease. Widespread application of the most widely used mGlu5 tracer, [11C]ABP688, is limited by the short physical half-life of carbon-11. [18F]PSS232 is a fluorinated analog with promising preclinical properties and high selectivity and specificity for mGlu5. In this first-in-man study, we evaluated the brain uptake pattern and kinetics of [18F]PSS232 in healthy volunteers. METHODS [18F]PSS232 PET was performed with ten healthy male volunteers aged 20-40 years. Seven of the subjects received a bolus injection and the remainder a bolus/infusion protocol. Cerebral blood flow was determined in seven subjects using [15O]water PET. Arterial blood activity was measured using an online blood counter. Tracer kinetics were evaluated by compartment modeling and parametric maps were generated for both tracers. RESULTS At 90 min post-injection, 59.2 ± 11.1% of total radioactivity in plasma corresponded to intact tracer. The regional first pass extraction fraction of [18F]PSS232 ranged from 0.41 ± 0.06 to 0.55 ± 0.03 and brain distribution pattern matched that of [11C]ABP688. Uptake kinetics followed a simple two-tissue compartment model. The volume of distribution of total tracer (V T, ml/cm3) ranged from 1.18 ± 0.20 for white matter to 2.91 ± 0.51 for putamen. The respective mean distribution volume ratios (DVR) with cerebellum as the reference tissue were 0.88 ± 0.06 and 2.12 ± 0.10, respectively. The tissue/cerebellum ratios of a bolus/infusion protocol (30/70 dose ratio) were close to the DVR values. CONCLUSIONS Brain uptake of [18F]PSS232 matched the distribution of mGlu5 and followed a two-tissue compartment model. The well-defined kinetics and the possibility to use reference tissue models, obviating the need for arterial blood sampling, make [18F]PSS232 a promising fluorine-18 labeled radioligand for measuring mGlu5 density in humans.
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Affiliation(s)
- Geoffrey Warnock
- Department of Nuclear Medicine, University Hospital Zurich, 8091, Zurich, Switzerland
| | - Michael Sommerauer
- Department of Nuclear Medicine, University Hospital Zurich, 8091, Zurich, Switzerland.,Department of Neurology, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Linjing Mu
- Department of Nuclear Medicine, University Hospital Zurich, 8091, Zurich, Switzerland
| | - Gloria Pla Gonzalez
- Radiopharmaceutical Science, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog Weg 4, 8093, Zurich, Switzerland
| | - Susanne Geistlich
- Radiopharmaceutical Science, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog Weg 4, 8093, Zurich, Switzerland
| | - Valerie Treyer
- Department of Nuclear Medicine, University Hospital Zurich, 8091, Zurich, Switzerland
| | - Roger Schibli
- Radiopharmaceutical Science, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog Weg 4, 8093, Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, 8091, Zurich, Switzerland
| | - Stefanie D Krämer
- Radiopharmaceutical Science, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog Weg 4, 8093, Zurich, Switzerland
| | - Simon M Ametamey
- Radiopharmaceutical Science, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog Weg 4, 8093, Zurich, Switzerland.
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