Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of a Liver-Targeting Acetyl-CoA Carboxylase Inhibitor (PF-05221304): A Three-Part Randomized Phase 1 Study

PF-05221304 is a liver-targeted inhibitor of acetyl-CoA carboxylase, an enzyme that catalyzes the first committed step in de novo lipogenesis (DNL). This first-in-human study investigated safety/tolerability and pharmacokinetics of single and multiple ascending oral PF-05221304 doses, and fructose-stimulated DNL inhibition with repeated oral doses. Healthy subjects (n = 96) received single (1-240 mg) or repeated (2-200 mg daily) doses for 14 days or single 100-mg doses with and without food. PF-05221304 was well tolerated at all doses. Repeated PF-05221304 doses inhibited hepatic DNL in a dose-dependent manner, with near-complete inhibition seen at higher doses. With doses yielding >= 90% DNL inhibition, asymptomatic increases in fasting/postprandial serum triglyceride levels (>= 40 mg/day) and declines in platelet count (>= 60 mg/day) occurred; these were not observed at <= 80% DNL inhibition. Steady-state pharmacokinetics generally increased dose-proportionally, with a half-life of 14-18 hours and a minimal food effect on plasma exposure. The observed safety and tolerability, pharmacokinetics, and pharmacodynamics support the continued evaluation of PF-05221304 for the treatment of nonalcoholic steatohepatitis.