Eighth Tysabri patient falls ill
NEW YORK - Biogen Idec Inc. said a patient taking its multiple sclerosis drug Tysabri was diagnosed with a life-threatening brain illness, the eighth case reported in the last year.
The patient was confirmed to have progressive multifocal leukoencephalopathy, or PML, on Wednesday, according to a report on Cambridge, Mass.-based Biogen Idec's website. About 56,700 patients have been treated with Tysabri, the firm said.
Biogen Idec and marketing partner Elan Corp. pulled Tysabri from the market in 2005 after three patients developed the brain infection, including two who died. The Food and Drug Administration allowed sales to resume in July 2006 after deciding benefits for slowing MS relapses outweighed the risk. There were no reported infections for about two years after the drug's reintroduction.
The likelihood of getting PML from Tysabri is about 1 in 1,000, according to the drug's label. The infection occurs when a common germ mutates, then evades the body's immune defenses and penetrates the brain, causing irreversible damage. Researchers theorize that Tysabri may subdue defenses meant to keep the virus out of the brain. The virus breeds in brain cells, destroying them when it replicates.
On April 9, Genentech Inc., which was acquired in March by Roche Holding AG, said it was pulling its psoriasis treatment Raptiva from the US market because of the drug's link to PML.
