Safety and effectiveness of peficitinib 100 mg/day in patients achieving clinical remission from a long-term open-label extension study in Japan, Korea, and Taiwan (RAJ2)

Objectives: This post hoc analysis of the RAJ2 study assessed long-term safety and effectiveness of peficitinib 100 mg/day for treatment of rheumatoid arthritis.

Methods: Eligible patients previously completed two Phase 3 (RAJ3 and RAJ4) studies of peficitinib in Asia. All patients received peficitinib 100 mg/day at RAJ2 Week (W)0; dose change to 50 mg/day or 150 mg/day was permitted. Safety endpoints included treatment-emergent adverse events and laboratory test results. Effectiveness endpoints included peficitinib exposure pattern, achievement of Clinical Disease Activity Index (CDAI) remission by peficitinib exposure pattern at W0 and W48, and association of demographics/characteristics with CDAI remission at W0 and W48.

Results: Overall, no new safety findings were reported at W48, and renal function was unaffected. Of patients included in effectiveness analyses at W48, 70.9% (451/636) had maintained peficitinib 100 mg/day since W0. Of patients who achieved CDAI remission at W0 and maintained peficitinib 100 mg/day to W48, 50.3% (79/157) maintained CDAI remission to W48. Low disease activity and a lower number of prior disease-modifying antirheumatic drugs were significantly associated with CDAI remission at W48.

Conclusions: Long-term peficitinib treatment at a dose of 100 mg/day was generally well tolerated and, following induction therapy, maintained effectiveness through to W48.