Two studies of Tysabri see little risk

Tysabri, withdrawn last year because of fears it might cause an often-deadly brain disorder, slows the progression of multiple sclerosis and seems to pose little risk, two studies showed yesterday.

The studies were financed by the drug's manufacturers and come as a US Food and Drug Administration panel is to meet on March 7 to discuss whether Tysabri should go back on the market.

The drug, also known by the generic name natalizumab, was removed by Cambridge-based Biogen Idec Inc. and its marketing partner Elan Corp. of Ireland, just over a year ago after three patients developed a rare brain disease.

The studies, published in this week's New England Journal of Medicine, reported no new cases of the brain disease.

Researchers in the first study found that Tysabri cut the likelihood of a relapse by 68 percent in 627 patients, compared to the 315 patients who got a placebo.

The second study looked at volunteers who had suffered a recent relapse despite treatment with interferon beta.

Among 582 patients receiving just interferon, 32 percent did not have a relapse after two years. The rate was 54 percent among 589 who also got Tysabri.