Combination treatment with infliximab and leflunomide in patients with active rheumatoid arthritis: safety and efficacy in an open-label clinical trial

Objective To assess the safety and efficacy of combination therapy with infliximab and leflunomide in adults with active rheumatoid arthritis (RA) despite leflunomide therapy. Methods Adult patients with active RA who had received leflunomide for at least 16 weeks were eligible for this 30-week, open-label trial. All patients received ongoing oral leflunomide (20 mg/day) and 3 mg/kg infliximab administered IV at weeks 0, 2, 6, 14, and 22. The primary end point was the percentage of patients with adverse events that led to patient withdrawal and were at least possibly related to treatment. Descriptive evaluations of efficacy and other safety assessments were performed. Results Twelve out of 70 patients (17.1%; upper 90% CI 24.5%) withdrew due to treatment-related adverse events. Adverse events were reported in 69 of 72 patients (95.8%); the most common were nasopharyngitis, diarrhea, and pruritis. Serious adverse events occurred in 16 out of 72 patients (22.2%). Significant improvements were observed in efficacy assessments, including Disease Activity Score 28 (DAS28) and pain. At end point, 19.4% of the patients showed a good improvement in DAS28 score and 46.3% had a moderate improvement. American College of Rheumatology (ACR) 20, 50, and 70 responses were achieved by 47.1%, 21.4%, and 12.9% of the patients, respectively. Conclusion The combination of infliximab and leflunomide neither increased the rate of toxicities nor resulted in unexpected adverse events. Treatment-related withdrawals occurred at an acceptable frequency. Patients experienced clinically significant improvements. Treatment with infliximab plus leflunomide benefits the majority of patients, but monitoring of adverse events is required.