Effectiveness of disease-modifying antirheumatic drug co-therapy with methotrexate and leflunomide in rituximab-treated rheumatoid arthritis patients: results of a 1-year follow-up study from the CERERRA collaboration

Objectives To compare the effectiveness and safety of rituximab alone or in combination with either methotrexate or leflunomide. Methods 10 European registries submitted anonymised datasets with baseline, 3, 6, 9 and 12-month clinical data from patients who started rituximab. Results 1195 patients were treated with rituximab plus methotrexate, 177 with rituximab plus leflunomide and 505 with rituximab alone. Significantly more patients achieved a European League Against Rheumatism good response at 6 months when treated with rituximab plus leflunomide (29.1%) compared with rituximab plus methotrexate (21.1%) and rituximab alone (19.3%; p=0.02 and p=0.01, respectively). Similar results were observed at 12 months. Adverse events occurred in 10.2%, 13.2% and 13.9% of patients on rituximab plus leflunomide, rituximab plus methotrexate and rituximab alone, respectively. Conclusions Leflunomide is an effective and safe alternative to methotrexate as concomitant treatment with rituximab. Slightly better results were obtained by the combination of rituximab and leflunomide than rituximab and methotrexate, raising the possibility of a synergistic effect of leflunomide and rituximab.