BUSINESS BRIEFING / PHARMACEUTICALS

Three patients taking the Genentech Inc. drug Raptiva are believed to have died of a rare brain infection, a known risk with the skin-clearing treatment, according to federal health officials.

The Food and Drug Administration confirmed three cases and a possible fourth of progressive multifocal leukoencephalopathy, or PML, which causes swelling of the brain and is usually fatal. All the cases were reported in the last six months.