Genentech’s oncology blockbuster Rituxan could be an effective treatment for multiple sclerosis, according to data from a new study.

The small 104-patient study, published in the New England Journal of Medicine, demonstrated that Rituxan (rituximab) had a significant effect in treating relapsing-remitting MS, the most common form of the disease. The authors of the trial, sponsored by Genentech and marketing partner Biogen Idec, showed that the drug dramatically reduced the number of inflammatory lesions that form along nerve fibres in patients’ brains, “the hallmark of the disease”.

Rituxan, which is approved for non-Hodgkin's lymphoma and rheumatoid arthritis, also significantly decreased the clinical symptoms of the disease, ie sporadic, temporary disruptions in certain neurological functions, such as mobility in a limb or vision in an eye. Participants in the study received one course of rituximab, intravenously, and were examined regularly with brain scans and clinical evaluations.

At the primary endpoint, week 24, those receiving Rituxan had a 91% reduction in inflammatory lesions and a 58% decrease in the number of relapses, compared to patients receiving placebo. Results were comparable at week 48 and adverse events were the same between both groups.

Principal investigator of the 32-centre study, Stephen Hauser, chair of the Department of Neurology at University of California, San Francisco, said that “the magnitude and rapidity of the drug’s effect suggest that therapies targeting B-cells may provide an important treatment strategy if proven effective and safe in larger and longer-term clinical trials”. Since the early 1970s, scientists have focused on the role of T-cells in MS, and all currently available therapies target them, rather than B-cells.

He added that “these findings shift the perspective on the cause of MS and open up a new frontier for investigation.” The discovery that B-cell depletion has such an impact on MS is “a beautiful proof of principle,” concluded Prof Hauser. “It signals a paradigm shift in our understanding of how MS develops.”