Genentech, Inc. and Biogen Idec, Inc. has announced that a phase II study of Rituxan (Rituximab) for relapsing-remitting multiple sclerosis (RRMS) met its primary endpoint.

The study of 104 patients showed a statistically significant reduction in the total number of gadolinium enhancing T1 lesions observed on serial MRI scans of the brain at weeks 12, 16, 20 and 24 in the Rituxan-treated group compared to placebo. Genentech and Biogen Idec will continue to analyze the study results and will submit the data for presentation at an upcoming medical meeting.

"These initial results exceeded our expectations," said Hal Barron, MD, Genentech senior vice president, development and chief medical officer. "Showing a significant benefit at 24 weeks in this small phase II trial supports our hypothesis that selective B-cell targeted therapy may play an important role in the treatment of MS."

"Biogen Idec is committed to offering multiple options, for people living with MS, a devastating disease. We are very encouraged by these data and look forward to learning more about the potential of Rituxan as a therapy to treat MS," said Alfred Sandrock, MD, PhD., senior vice president, neurology research and development, Biogen Idec.

Rates of overall adverse events and serious adverse events were comparable between the two treatment groups. Serious infectious adverse events occurring in Rituxan-treated patients included gastroenteritis and bronchitis. The overall rates of infection were comparable among the two treatment groups with an increase in the rates of nasopharyngitis, upper respiratory tract infections, urinary tract infections and sinusitis in the Rituxan-treated patients.

There were more first infusion-related reactions with Rituxan, the majority of which were mild to moderate and were generally reversible with medical intervention. The companies continue to monitor the long-term safety of Rituxan treatment.