Updates from B Cell Trials: Efficacy.

Recent reports of data from ongoing trials have contributed substantially to our growing understanding of the potential effectiveness and safety of B cell targeted therapy in the treatment of rheumatic diseases. In addition, the results have addressed practical questions regarding the administration of specific agents. Phase II trials of rituximab (RTX) have provided data supporting efficacy in rheumatoid arthritis (RA), including more clearly defining the role of glucocorticoids in the treatment and exploring the doses necessary to improve the signs and symptoms of RA. The Phase IIb Dose-Ranging Assessment International Clinical Evaluation of Rituximab in RA (DANCER) trial demonstrated that a significant percentage of patients achieved clinical improvement when treated with different doses of RTX as compared with those given placebo. The Phase III Randomized Evaluation of Long-Term Efficacy of Rituximab in RA (REFLEX) trial demonstrated efficacy of RTX in patients with a history of nonresponse to tumor necrosis factor inhibitors. Preliminary results of a small cohort of patients receiving RTX retreatment demonstrated efficacy with repeat administration. Phase II results of another B cell targeted therapy, anti-B lymphocyte stimulator protein, demonstrated efficacy. The efficacy of the agent, belimumab, resulted in an ACR20 response that was significantly higher in patients treated with belimumab versus placebo and in patients with RA. These findings support the hypothesis that B cells play an integral role in the pathogenesis of RA, and this report will review the efficacy results of clinical trials targeting B cells.