FDA approval for Stemline Therapeutics Inc.'s Elzonris (tagraxofusp) has made it the first drug ever approved for blastic plasmacytoid dendritic cell neoplasm (BPDCN), a rare and aggressive disease of the bone marrow and blood. The green light, which covers both adult and pediatric patients ages 2 and older, arrived two months ahead of the date by which the regulator was expected to release its decision.