[11C-carbonyl]CEP-32496: Radiosynthesis, biodistribution and PET study of brain uptake in P-gp/BCRP knockout mice

CEP-32496 is a novel, orally active serine/threonine-protein kinase B-raf (BRAF) (V600E) kinase inhibitor that is being investigated in clinical trials for the treatment of some cancers in patients. In this study, we developed [11C-carbonyl]CEP-32496 as a novel positron emission tomography (PET) probe to study its biodistribution in the whole bodies of mice. [11C]CEP-32496 was synthesized by the reaction of 5-(1,1,1-trifluoro-2-methylpropan-2-yl)isoxazol-3-amine hydrochloride (1·HCl) with [11C]phosgene, followed by treatment with 3-(6,7-dimethoxyquinozolin-4-yloxy)aniline (2). Small-animal PET studies with [11C]CEP-32496 indicated that radioactivity levels (AUC0-90 min, SUV × min) accumulated in the brains of P-gp/BCRP knockout mice at a 8-fold higher rate than in the brains of wild-type mice.