Genentech and Biogen Idec received approval from the FDA for the therapeutic antibody Rituxan in combination with methotrexate (MTX) to reduce signs and symptoms in adult patients with moderate-to-severe rheumatoid arthritis (RA) who have had an inadequate response to one or more tumor necrosis factor (TNF) antagonist therapies. Rituxan is the first treatment for RA that selectively targets immune cells known as CD20-positive B-cells. Through this unique mechanism of action, Rituxan may affect multiple pathways by which B-cells are believed to contribute to the initiation and development of RA.

The approval was based on data from three randomized, double blind, placebo-controlled studies of patients with active RA. Results of the Phase III trial, known as REFLEX, showed that a significantly greater proportion of patients who received a single treatment course of two infusions of Rituxan with a stable dose of MTX achieved American College of Rheumatology (ACR) 20, 50 and 70 response rates compared to patients who received placebo and MTX. At 24 weeks, patients receiving Rituxan displayed clinically and statistically significant improvements in RA signs and symptoms, including pain and disability. Rituxan was also shown to reduce biologic markers of inflammation.