After the market close, Biogen (BIIB) filed an 8-K with the SEC reporting a new case of the potentially fatal brain disease known as PML or progressive multifocal leukoencephalopathy in a patient receiving their multiple sclerosis [MS] drug Tysabri, adding to the two new cases which were reported previously in July. Biogen is currently trading down by about 15% after hours while marketing partner Elan (ELN) is down by about 25% as of 5:15 PM. The news adds more uncertainty to Tysabri, which was removed from th



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