March 30, 2005 -- Elan and Biogen Idec jointly revealed that their co-developed MS drug, Tysabri, has caused another death. Once again, the culprit is progressive multifocal leukoencephalopathy (PML). When Tysabri was abruptly pulled from the market on February 28th, the two cases of PML were MS patients who had been taking both Tysabri and Avonex, the other MS drug from Biogen Idec. Company officials hinted that the side-effects may have been caused by some unknown interaction between the two drugs. In this latest case, the patient was not taking Avonex, and this may be the death knell for Tysabri. More detail...
