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WASHINGTON (Dow Jones)--Patients are at a greater risk of getting a rare brain infection with Biogen Idec Inc.'s (BIIB) Tysabri as the number of infusions of the medicine increase, the U.S. Food and Drug Administration said in a letter to doctors Friday.
The FDA said it has confirmed 31 cases of progressive multifocal leukoencephalopathy, or PML, a rare brain infection, in patients taking the multiple sclerosis treatment as of Jan. 21. The FDA said eight of those patients died.
The agency said the benefits of the medicine, sold with Elan ...
