This randomised, double-blind, parallel-group, phase 3 study compared monotherapy with sirukumab, an anti-interleukin-6 cytokine monoclonal antibody, with adalimumab monotherapy in patients with rheumatoid arthritis (RA).
Biologic-naïve patients with active RA who were inadequate responders or were intolerant to, or inappropriate for, methotrexate were randomised to subcutaneous sirukumab 100 mg every 2 weeks (n=187), sirukumab 50 mg every 4 weeks (n=186) or adalimumab 40 mg every 2 weeks (n=186). Primary endpoints at week 24 were change from baseline in Disease Activity Score in 28 joints (DAS28) using erythrocyte sedimentation rate (ESR) and proportion of patients achieving an American College of Rheumatology (ACR) 50 response; these endpoints were tested in sequential order. This study is registered at EudraCT (number: 2013-001417-32) and ClinicalTrials.gov (number: NCT02019472).
Significantly greater improvements from baseline in mean (SD) DAS28 (ESR) were observed at week 24 with sirukumab 100 mg every 2 weeks (-2.96 (1.580)) versus adalimumab 40 mg every 2 weeks (-2.19 (1.437); P<0.001). Sirukumab 50 mg every 4 weeks also showed significantly greater improvement from baseline at week 24 in DAS28 (ESR) (-2.58 (1.524)) compared with adalimumab (P=0.013). The ACR50 response rates with the 100 mg (35.3%) and 50 mg (26.9%) doses of sirukumab were comparable to that with adalimumab (31.7%) at week 24. The safety profile of sirukumab was consistent with that observed with anti-interleukin-6 receptor antibodies. A dose-related effect on the incidence of injection-site reactions was observed with sirukumab.
Sirukumab monotherapy showed greater improvements in DAS28 (ESR), but similar ACR50 response rates, versus adalimumab monotherapy.