WASHINGTON (AP) — Federal health officials are warning doctors that the risk of a deadly brain inflammation linked to the multiple sclerosis treatment Tysabri increases with use of the drug.
Tysabri has been plagued for years by rare cases of progressive multifocal leukoencephalopathy, or PML, which can cause swelling of the brain that is usually fatal. It is mostly seen in patients with immune deficiencies.
The biotech drug is marketed by Cambridge, Mass.-based Biogen Idec Inc. and Irish drugmaker Elan Corp. PLC, for multiple sclerosis and Crohn's disease.
