Abstract
Ibrutinib is a first-generation Bruton's tyrosine kinase (BTK) inhibitor that has shown efficacy in autoimmune diseases and has consequently been developed as a positron emission tomography (PET) radiotracer. Herein, we report the automated radiosynthesis of [(11)C]ibrutinib through (11)C-carbonylation of the acrylamide functional group, by reaction of the secondary amine precursor with [(11)C]CO, iodoethylene, and palladium-NiXantphos. [(11)C]Ibrutinib was reliably formulated in radiochemical yields of 5.4% ± 2.5% (non-decay corrected; n = 9, relative to starting [(11)C]CO(2)), radiochemical purity >99%, and molar activity of 58.8 ± 30.8 GBq/μmol (1.55 ± 0.83 Ci/μmol). Preliminary PET/magnetic resonance imaging with [(11)C]ibrutinib in experimental autoimmune encephalomyelitis (EAE) mice showed a 49% higher radioactivity accumulation in the spinal cord of mice with EAE scores of 2.5 vs. sham mice.