MarketWatch
Market Pulse: Elan down over 20% on fourth Tysabri death report
Thursday June 2, 7:01 am ET
By Steve Goldstein
LONDON (MarketWatch) -- Elan Corp. tumbled over 20% in European trade after the Boston Globe said that its partner, Biogen Idec Inc. , has told the Food and Drug Administration that a fourth patient may have contracted a potentially deadly brain disease after being treated with the company's multiple sclerosis drug Tysabri. Because the brain disease, PML, is so rare, each additional confirmed case magnifies the drug's potential risks, the report said.