Many multiple sclerosis patients treated with Tysabri remain free of disease activity for two years, Biogen Idec Inc. and Elan Corp. said.
The companies said a study has shown that five times as many MS patients taking Tysabri were free from disease activity compared with those on a placebo in the overall patient population.
"Results from this retrospective analysis showed that two years after beginning treatment with Tysabri, 37 percent of patients remained free of disease activity, compared to 7 percent of placebo-treated patients," the companies said. "Sixty-four percent of patients showed no sign of relapse or sustained disability progression, and 58 percent were free of radiological disease activity."
Tysabri's sales growth has slowed amid growing concerns about a potentially deadly side effect, a brain disease called progressive multifocal leukoencephalopathy.
