Biogen Idec reports eighth case of PML in patient taking Tysabri

Biogen Idec announced that an additional patient with multiple sclerosis who took Tysabri (natalizumab) was diagnosed with progressive multifocal leukoencephalopathy (PML), bringing the total number of cases to eight since July 2006. The drug is co-marketed with Elan.

According to a weekly update posted to Biogen Idec's website, the most recent patient to be diagnosed with the brain infection took 35 doses of Tysabri. The product had sales of $813 million in 2008.

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