Sirukumab, a human anti-interleukin-6 monoclonal antibody: a randomised, 2-part (proof-of-concept and dose-finding), phase II study in patients with active rheumatoid arthritis despite methotrexate therapy

Objectives The safety and efficacy of sirukumab, an anti-interleukin-6 (IL-6) monoclonal antibody, were evaluated in a 2-part, placebo-controlled phase II study of patients with active rheumatoid arthritis (RA) despite methotrexate therapy. Methods In Part A (proof-of-concept), 36 patients were randomised to placebo or sirukumab 100 mg every 2 weeks (q2w) through week 10, with crossover treatment during weeks 12–22. In Part B (dose finding), 151 patients were randomised to sirukumab (100 mg q2w, 100 mg q4w, 50 mg q4w, or 25 mg q4w) through week 24, or placebo through week 10 with crossover to sirukumab 100 mg q2w (weeks 12–24). The proportion of patients with an American College of Rheumatology 50 (ACR50) response and the change from baseline in the 28-joint count disease activity score using C-reactive protein (DAS28-CRP) were determined. Safety was evaluated through week 38 in both parts. Results The primary endpoint (ACR50 at week 12 in Part B) was achieved only with sirukumab 100 mg q2w versus placebo (26.7% vs 3.3%; p=0.026). Greater improvements in mean DAS28-CRP at week 12 were observed with sirukumab 100 mg q2w versus placebo in Parts A (2.1 vs 0.6, p