Safety and tolerability of sifalimumab, an anti-interferon-α monoclonal antibody, in Japanese patients with systemic lupus erythematosus: A multicenter, phase 2, open-label study

Objectives: To evaluate the safety of sifalimumab in Japanese patients with systemic lupus erythematosus (SLE). Methods: This phase 2, open-label study consisted of a 52-week initial stage (Stage I) and a long-term extension (Stage II). In Stage I, sequential cohorts of patients received ascending doses of sifalimumab (intravenous [IV] 1.0, 3.0, and 10.0 mg/kg or subcutaneous 100 mg every 2 weeks; IV 600 and 1200 mg every 6 weeks). In Stage II, patients enrolled before June 2012 received the same dose of sifalimumab as during Stage I for up to 157 weeks or sifalimumab 600 mg IV every 4 weeks if they enrolled later. The safety of sifalimumab was assessed by adverse events (AEs). Results: Thirty patients enrolled in Stage I and 21 patients entered Stage II. The majority of patients experienced AEs (96.7% in Stage I and 100% in Stage II); most were mild or moderate in severity. Serious AEs occurred in 30.0% and 57.1% of patients in Stage I and II, respectively; most were instances of SLE flares. The proportion of patients in Stage I and II who had AEs leading to discontinuation was 10.0% and 28.6%, respectively. Conclusion: Sifalimumab was well tolerated in Japanese patients with SLE.