To assess the safety of rituximab in combination with a tumor necrosis factor (TNF) inhibitor and methotrexate (MTX) in patients with rheumatoid arthritis (RA).

Adult patients with active RA (≥ 5 swollen and ≥ 5 tender joints) receiving a stable dose of MTX (10-25 mg/week) and stable dose of TNF inhibitor (etanercept or adalimumab) for ≥ 12 weeks were randomized 2:1 to receive one course of rituximab or placebo, given intravenously at a dose of 2 × 500 mg. The primary end point was the proportion of patients developing ≥ 1 serious infection through week 24.

Fifty-one patients were treated with either rituximab or placebo in combination with background MTX and a TNF inhibitor. Baseline characteristics were generally balanced between groups, except for corticosteroid usage (36% in the rituximab arm versus 17% in the placebo arm). A serious infection (pneumonia) was observed in 1 patient (3%) in the rituximab group after 14.4 patient-years of exposure (6.95 events per 100 patient-years, 95% confidence interval 0.98-49.35), compared with none in the placebo group at week 24. Infections were reported in 18 patients (55%) and 11 patients (61%) in the rituximab and placebo groups, respectively. Grade 3 infections were reported in 3 patients (9%) receiving rituximab and in none of the patients receiving placebo. No grade 4 infections were observed, nor were there any opportunistic, fungal, or tuberculosis infections. Serious adverse events (SAEs) were reported in 2 rituximab-treated patients (pneumonia and coronary artery occlusion), whereas there were no SAEs reported in placebo-treated patients. At week 24, the percentage of patients achieving an American College of Rheumatology 20% (ACR20) improvement response was 30% in the rituximab group compared with 17% in the placebo group, and ACR50 responses were achieved by 12% and 6% of patients, respectively.

The preliminary safety profile of rituximab in combination with a TNF inhibitor and MTX was consistent with the safety profile of rituximab in combination with MTX in other RA trials without a TNF inhibitor, with no new safety signals observed. SAEs were numerically more frequent in the rituximab group, and there was no clear evidence of an efficacy advantage in patients receiving rituximab in combination with a TNF inhibitor and MTX.