Successful sequential therapy with rituximab and belimumab in patients with active systemic lupus erythematosus: a case series

Objective. B cells play an important role in the initiation and progression of systemic lupus erythematosus (SLE). Accordingly, B cell-targeted therapy has been suggested as a new rational approach for treating lupus. Belimumab, a human monoclonal antibody directed against B lymphocyte stimulator (BLyS), was reported as the first biological treatment effective in reducing mild-to-moderate SLE disease activity by using different scoring systems and endpoints. Conversely clinical trials with rituximab, a chimeric monoclonal antibody directed against the CD20 expressed by B cells, have failed to achieve primary endpoints in spite of a number of reports showing its beneficial effects. Anecdotal reports have described the sequential use of rituximab and belimumab as a more effective treatment than using the individual drugs alone, without compromising safety. Methods. We report a case series of three patients with active SLE refractory to conventional therapies, who underwent treatment with rituximab followed by belimumab as maintenance therapy. Results. We observed a beneficial effect after sequential treatment with rituximab and belimumab. All patients achieved long-standing remission and could reduce or discontinue corticosteroids. Concomitantly, after rituximab administration we observed a rise in BLyS levels, which were dramatically reduced after belimumab introduction. Conclusion. The modulation of plasma BLyS kinetics in patients undergoing sequential treatment with rituximab and belimumab may represent a possible rationale behind the effectiveness of this combined therapy.