Current FDA Alert: [issued 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. Healthcare Professional Sheet

Previous FDA Alert: [issued 2/2006]

The FDA has lifted the clinical hold on Biogen-IDEC's trials of natalizumab for patients with multiple sclerosis (MS). Biogen-IDEC can now resume administration of natalizumab to patients with relapsing-remitting MS who had previously been treated with the drug in clinical trials. Biogen-IDEC had previously suspended marketing of natalizumab and all further dosing of patients in on-going clinical trials. This decision was made after confirmation of one fatal case and one additional case of severely disabling progressive multifocal leukoencephalopathy (PML) in patients receiving natalizumab for MS. A third case of PML, this one fatal, in a patient with Crohn's Disease had been identified shortly thereafter. Healthcare Professional Sheet