UNLABELLED: The enzyme phosphodiesterase 2A (PF-05270430) is a potential target for development of novel therapeutic agents for the treatment of cognitive impairments. The goal of the present study was to evaluate the PDE2A ligand (18)F-PF-05270430, 4-(3-fluoroazetidin-1-yl)-7-methyl-5-(1-methyl-5-(4-(trifluoromethyl)phenyl)-1H-pyrazol-4-yl)imidazo[1,5-f][1,2,4]triazine, in nonhuman primates. METHODS: (18)F-PF-05270430 was radiolabeled by 2 methods via nucleophilic substitution of its tosylate precursor. Tissue metabolite analysis in rodents and PET imaging in nonhuman primates under baseline and blocking conditions were performed to determine the pharmacokinetic and binding characteristics of the new radioligand. Various kinetic modeling approaches were assessed to select the optimal method for analysis of imaging data. RESULTS: (18)F-PF-05270430 was synthesized in greater than 98% radiochemical purity and high specific activity. In the nonhuman primate brain, uptake of (18)F-PF-05270430 was fast, with peak concentration (SUVs of 1.5-1.8 in rhesus monkeys) achieved within 7 min after injection. The rank order of uptake was striatum > neocortical regions > cerebellum. Regional time-activity curves were well fitted by the 2-tissue-compartment model and the multilinear analysis-1 (MA1) method to arrive at reliable estimates of regional distribution volume (VT) and binding potential (BPND) with 120 min of scan data. Regional VT values (MA1) ranged from 1.28 mL/cm(3) in the cerebellum to 3.71 mL/cm(3) in the putamen, with a BPND of 0.25 in the temporal cortex and 1.92 in the putamen. Regional BPND values estimated by the simplified reference tissue model (SRTM) were similar to those from MA1. Test-retest variability in high-binding regions (striatum) was 4% ± 6% for MA1 VT, 13% ± 6% for MA1 BPND, and 13% ± 7% SRTM BPND, respectively. Pretreatment of animals with the PDE2A inhibitor PF-05180999 resulted in a dose-dependent reduction of (18)F-PF-05270430 specific binding, with a half maximal effective concentration of 69.4 ng/mL in plasma PF-05180999 concentration. CONCLUSION: (18)F-PF-05270430 displayed fast and reversible kinetics in nonhuman primates, as well as specific binding blockable by a PDE2A inhibitor. This is the first PET tracer with desirable imaging properties and demonstrated ability to image and quantify PDE2A in vivo.
UNLABELLED: The enzyme phosphodiesterase 2A (PF-05270430) is a potential target for development of novel therapeutic agents for the treatment of cognitive impairments. The goal of the present study was to evaluate the PDE2A ligand (18)F-PF-05270430, 4-(3-fluoroazetidin-1-yl)-7-methyl-5-(1-methyl-5-(4-(trifluoromethyl)phenyl)-1H-pyrazol-4-yl)imidazo[1,5-f][1,2,4]triazine, in nonhuman primates. METHODS: (18)F-PF-05270430 was radiolabeled by 2 methods via nucleophilic substitution of its tosylate precursor. Tissue metabolite analysis in rodents and PET imaging in nonhuman primates under baseline and blocking conditions were performed to determine the pharmacokinetic and binding characteristics of the new radioligand. Various kinetic modeling approaches were assessed to select the optimal method for analysis of imaging data. RESULTS: (18)F-PF-05270430 was synthesized in greater than 98% radiochemical purity and high specific activity. In the nonhuman primate brain, uptake of (18)F-PF-05270430 was fast, with peak concentration (SUVs of 1.5-1.8 in rhesus monkeys) achieved within 7 min after injection. The rank order of uptake was striatum > neocortical regions > cerebellum. Regional time-activity curves were well fitted by the 2-tissue-compartment model and the multilinear analysis-1 (MA1) method to arrive at reliable estimates of regional distribution volume (VT) and binding potential (BPND) with 120 min of scan data. Regional VT values (MA1) ranged from 1.28 mL/cm(3) in the cerebellum to 3.71 mL/cm(3) in the putamen, with a BPND of 0.25 in the temporal cortex and 1.92 in the putamen. Regional BPND values estimated by the simplified reference tissue model (SRTM) were similar to those from MA1. Test-retest variability in high-binding regions (striatum) was 4% ± 6% for MA1 VT, 13% ± 6% for MA1 BPND, and 13% ± 7% SRTM BPND, respectively. Pretreatment of animals with the PDE2A inhibitor PF-05180999 resulted in a dose-dependent reduction of (18)F-PF-05270430 specific binding, with a half maximal effective concentration of 69.4 ng/mL in plasma PF-05180999 concentration. CONCLUSION: (18)F-PF-05270430 displayed fast and reversible kinetics in nonhuman primates, as well as specific binding blockable by a PDE2A inhibitor. This is the first PET tracer with desirable imaging properties and demonstrated ability to image and quantify PDE2A in vivo.
Authors: Paul Morgan; Piet H Van Der Graaf; John Arrowsmith; Doug E Feltner; Kira S Drummond; Craig D Wegner; Steve D A Street Journal: Drug Discov Today Date: 2011-12-29 Impact factor: 7.851
Authors: Robert B Innis; Vincent J Cunningham; Jacques Delforge; Masahiro Fujita; Albert Gjedde; Roger N Gunn; James Holden; Sylvain Houle; Sung-Cheng Huang; Masanori Ichise; Hidehiro Iida; Hiroshi Ito; Yuichi Kimura; Robert A Koeppe; Gitte M Knudsen; Juhani Knuuti; Adriaan A Lammertsma; Marc Laruelle; Jean Logan; Ralph Paul Maguire; Mark A Mintun; Evan D Morris; Ramin Parsey; Julie C Price; Mark Slifstein; Vesna Sossi; Tetsuya Suhara; John R Votaw; Dean F Wong; Richard E Carson Journal: J Cereb Blood Flow Metab Date: 2007-05-09 Impact factor: 6.200
Authors: Lei Zhang; Anabella Villalobos; Elizabeth M Beck; Thomas Bocan; Thomas A Chappie; Laigao Chen; Sarah Grimwood; Steven D Heck; Christopher J Helal; Xinjun Hou; John M Humphrey; Jiemin Lu; Marc B Skaddan; Timothy J McCarthy; Patrick R Verhoest; Travis T Wager; Kenneth Zasadny Journal: J Med Chem Date: 2013-05-28 Impact factor: 7.446
Authors: Mika Naganawa; Rikki N Waterhouse; Nabeel Nabulsi; Shu-Fei Lin; David Labaree; Jim Ropchan; Sanela Tarabar; Nicholas DeMartinis; Adam Ogden; Anindita Banerjee; Yiyun Huang; Richard E Carson Journal: J Nucl Med Date: 2016-04-21 Impact factor: 10.057
Authors: Mika Naganawa; Rikki N Waterhouse; Nabeel Nabulsi; Shu-Fei Lin; David Labaree; Jim Ropchan; Sanela Tarabar; Nicholas DeMartinis; Adam Ogden; Anindita Banerjee; Yiyun Huang; Richard E Carson Journal: J Nucl Med Date: 2016-04-21 Impact factor: 10.057
Authors: Reagan Farmer; Steven D Burbano; Neema S Patel; Angelo Sarmiento; Abigail J Smith; Michy P Kelly Journal: Cell Signal Date: 2020-02-29 Impact factor: 4.315
Authors: Stuart P McCluskey; Christophe Plisson; Eugenii A Rabiner; Oliver Howes Journal: Eur J Nucl Med Mol Imaging Date: 2019-09-21 Impact factor: 9.236