Genentech and Biogen Idec’s successful cancer and rheumatoid arthritis drug Rituxan has shown promise in a small Phase II trial assessing its use for the treatment of relapsing remitting multiple sclerosis.

Results from the randomized, double-blind, 104-patient study revealed that those taking Rituxan showed a statistically significant reduction in the number of brain lesions associated with MS at weeks 12, 16, 20 and 24 compared to the placebo group.

“These initial results exceeded our expectations,” noted Hal Barron, Genentech’s Senior Vice President of 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,” he added.

Genentech and Biogen Idec said they will continue to analyse findings of the study, and plan to submit the data for presentation at an upcoming medical meeting.

Rituxan, which is sold in Europe under the trade name MabThera by Roche, is a therapeutic antibody that targets and selectively eradicates b-lymphocytes without harming stem cells or existing plasma cells. It received its first green light in the US in 1997 and Europe in 1998 for non-Hodgkin's lymphoma, and has since been cleared for the treatment of diffuse large B-cell lymphoma alongside certain chemotherapy, as well as in combination with methotrexate to reduce signs and symptoms of moderately-to-severely active rheumatoid arthritis.

Rituxan is already a blockbuster in non-Hodgkin's lymphoma, and is expected to make strong headway in rheumatoid arthritis because it works by a different mechanism of action to all the available drugs for the disease. And if it makes it to market for MS, the drug’s already solid performance will likely enjoy yet another significant boost.

Aside from RRMS, the drug is also being assessed for primary progressive MS, for which there is no approved therapy in the US, as well as in other autoimmune diseases with significant unmet medical needs, such as systemic lupus erythematosus, lupus nephritis and ANCA-associated vasculitis, the companies note.