Bank of America commented on Biogen Inc (NASDAQ: BIIB) Wednesday following the death of a patient due to fatal progressive multifocal leukoencephalopathy (PML) that was linked to dimethyl fumarate (DMF). Dimethyl fumarate is the active ingredient in Biogen’s multiple sclerosis drug,. Read More. Don t Miss Any Updates! News Directly in Your Inbox Subscribe to: