Efficacy and Safety of the TYK2/JAK1 Inhibitor Brepocitinib for Active Psoriatic Arthritis: A Phase IIb Randomized Controlled Trial

Brepocitinib is a TYK2/JAK1 inhibitor in development for the treatment of several immunologic diseases. The efficacy and safety of oral brepocitinib were assessed in participants with moderately-to-severely active psoriatic arthritis (PsA) for up to 52 weeks.In this placebo-controlled, dose-ranging, phase IIb study, participants were randomized to receive 10 mg, 30 mg, or 60 mg of brepocitinib once daily or placebo, advancing to 30 mg or 60 mg of brepocitinib once daily at week 16. The primary endpoint was the response rate according to the American College of Rheumatology criteria for 20% improvement (ACR20) in disease activity at week 16. Secondary endpoints included response rates according to the ACR50/ACR70 response criteria, 75% and 90% improvement in the Psoriasis Area and Severity Index (PASI75/PASI90) score, and minimal disease activity (MDA) at weeks 16 and 52. Adverse events were monitored throughout the study.Overall, 218 participants were randomized and treated. At week 16, the brepocitinib 30 mg and 60 mg once daily groups had significantly greater ACR20 response rates (66.7% [P = 0.0197] and 74.6% [P = 0.0006], respectively), versus the placebo group (43.3%), and significantly higher ACR50/ACR70, PASI75/PASI90, and MDA response rates. Response rates were maintained or improved through week 52. Adverse events were mostly mild/moderate; serious adverse events (15) in 12 participants (5.5%) included infections in 6 participants (2.8%) in the brepocitinib 30 mg and 60 mg once daily groups. No major adverse cardiovascular events or deaths occurred.Treatment with brepocitinib at dosages of 30 mg and 60 mg once daily was superior to placebo at reducing signs and symptoms of PsA. Brepocitinib was generally well tolerated throughout the 52-week study, with a safety profile consistent with those found in other brepocitinib clinical trials.