A Phase III clinical study of Rituxan (Rituximab) met its primary endpoint of a greater proportion of Rituxan-treated patients achieving an American College of Rheumatology (ACR) 20 response at week 24, compared to placebo. The study included patients with active rheumatoid arthritis (RA) who have had an inadequate response or were intolerant to prior treatment with one or more anti-TNF therapies, Genentech, Inc., Biogen Idec and Roche have jointly announced here.

In this study, known as REFLEX (Randomized Evaluation of Long-term Efficacy of Rituximab in RA), patients who received a single treatment course of two infusions of Rituxan with a stable dose of methotrexate (MTX) displayed a statistically significant improvement in symptoms compared to patients who received placebo and MTX. Further analyses of the data are ongoing and will be submitted for presentation at an upcoming medical meeting.

"These results continue to support the potential of Rituxan as a new therapeutic option for RA," Burt Adelman, executive vice president, development, Biogen Idec said adding, "We look forward to sharing the REFLEX data in our discussions with the FDA."

"These are the first Phase III Rituxan data to demonstrate clinical improvement in this difficult-to-treat RA patient population. The findings add to the growing body of evidence that selectively targeting B cells may provide an important new treatment approach for this debilitating disease," said Hal Barron, Genentech's senior vice president, development and chief medical officer.

These new Phase III data follow recent positive preliminary findings from a Phase IIb study that evaluated the efficacy and safety of Rituxan in moderate-to-severe RA patients who failed prior treatment with at least one disease-modifying anti-rheumatic drug (DMARD).

Rituxan is a therapeutic antibody that targets and selectively depletes peripheral CD20 positive B cells without targeting stem cells or existing plasma cells. B cells may play multiple roles in the pathophysiology of RA. Rituxan is also being investigated in other autoimmune diseases including lupus, multiple sclerosis and ANCA associated vasculitis.