Brain Infections Return for Multiple Sclerosis Drug Tysabri

Two patients taking the multiple sclerosis drug Tysabri have developed the type of brain infection that caused the drug to be temporarily pulled from the market a few years back. Biogen Idec and Elan, which co-market the drug, reported the cases of progressive multifocal leukoencephalopathy in SEC filings yesterday. These are the first cases of PML that [...] » Full Story on Wall Street Journal