MS Drug Tysabri May Cause Rare Brain Disease. The FDA has been informed by Biogen Idec Inc.
That a fourth person may now have died from a rare brain disease known as progressive multifocal leukoencephalopathy (PML).
deaths from PML which had led to the suspension of the drug
After being treated with its multiple sclerosis drug Tysabri. Biogen and its development partner, Elan Corp. PLC of Ireland, had hoped to return the drug to the market despite three previous deaths from PML which had led to the suspension of the drug on February 28 of this year.
The latest death, if linked to Tysabri, may prove to be an insurmountable obstacle to that plan. Word of that death caused shares of Elanâ€™s stock to plummet in value yesterday.