Safety of Abatacept Versus Placebo in Rheumatoid Arthritis: Integrated Data Analysis of Nine Clinical Trials

OBJECTIVE: To assess the safety of abatacept treatment in rheumatoid arthritis (RA) using integrated data from multiple clinical trials. METHODS: Data from nine double‐blind, placebo‐controlled studies of abatacept treatment (seven intravenous, two subcutaneous) in patients with RA were pooled, focusing on safety events in the double‐blind treatment period of each study. Incidence rates (IRs) of adverse events (AEs) per 100 patient‐years of exposure were calculated for abatacept‐ and placebo‐treated patients. AEs in abatacept‐treated patients were combined regardless of dose and formulation. RESULTS: In total, 2653 patients received abatacept and 1485 received placebo, with 2357 and 1254 patient‐years of exposure, respectively. The mean (SD) durations of exposure in the abatacept and placebo groups were 10.8 (3.3) and 10.3 (3.5) months, respectively. The IRs (95% confidence interval [CI]) for serious AEs were 14.8 (13.3, 16.5) and 14.6 (12.5, 17.0) in the abatacept and placebo groups, respectively. Death occurred in 12 (0.5%) and 12 (0.8%) patients in the abatacept and placebo groups, respectively, and was most commonly caused by cardiac disorders. Malignancies were observed in 31 patients (1.2%) treated with abatacept (IR: 1.32 [95% CI: 0.90, 1.87]) versus 14 (0.9%; IR: 1.12 [0.61, 1.88]) who received placebo. Solid organ tumor was the most frequent malignancy reported in both groups (abatacept: 1.0%; IR: 1.11 [95% CI: 0.72, 1.62]; placebo: 0.8%; 0.96 [0.50, 1.67]). CONCLUSION: In this integrated analysis, the IRs of safety events in the abatacept and placebo groups were similar with no new safety concerns identified.