Roche (OTCQX:RHHBY) is looking into a case of a potential deadly brain infection called progressive multifocal leukoencephalopathy (PML) that occurred in a German patient after taking one dose of MS drug Ocrevus (ocrelizumab). The person had been treated with Biogen's (BIIB +2.2%) Tysabri (natalizumab) for three years before switching.
Roche says the rare condition was reported as a carryover from Tysabri by the doctor treating the patient. Biogen declined comment on the matter.
There were no reported cases of PML in Ocrevus clinical trials, but the company included warnings about the risk from taking the drug.
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