FDA ALERT [8/2008]: The FDA has recently received information from the manufacturer about two new cases of progressive multifocal leukoencephalopathy (PML) in patients receiving Tysabri monotherapy for multiple sclerosis in Europe. Both patients had received Tysabri for more than one year. PML, which is usually fatal, is a known risk of Tysabri treatment, but previous cases in patients with multiple sclerosis were seen in combination with other immunomodulatory therapies. About 39,000 patients have received treatment with Tysabri worldwide, with about 12,000 patients having been treated for at least one year. No new cases have been seen in the US, where about 7,500 patients have received the drug for longer than one year and about 3,300 patients have received the drug for at least one and a half years. Read more from the FDA.
