Quoted from http://online.wsj.com/article/BT-CO-20091111-716035.html
Biogen Rethinking Disclosure Policies On MS Drug Tysabri
By Thomas Gryta Of DOW JONES NEWSWIRES
NEW YORK (Dow Jones)--Biogen Idec Inc. (BIIB) is re-evaluating the way it communicates new cases of a rare brain infection in patients on multiple sclerosis treatment Tysabri, sold with Elan Corp. (ELN), after regulators reported that the number of confirmed cases jumped in recent months.
In October, European and U.S. regulators said the number of cases of progressive multifocal leukoencephalopathy, or PML, has risen to 24, well above the Cambridge, Mass., biotech's July disclosure of 11, surprising Wall Street and sending Biogen shares down 7% and Elan's down 18%. Although both stocks have substantially recovered, some questioned Biogen's disclosure policies at the time and refusal to comment on PML case numbers.
The number of cases is important because if the infection rate climbs too high--it is generally consistent with the 1-in-1,000 patient rate implied by its label--sales of the drug may drop, damaging a product key to Biogen's future growth and that is Elan's biggest seller.
Tysabri's controversial history also has provoked fear in investors. Biogen withdrew the drug from the market for 18 months beginning in 2005 after three patients developed PML. Infections re-emerged last year, and Biogen provided regular updates to the public until July.
Biogen has been forced to deal with something that is unprecedented for a drug maker: keeping physicians and patients informed about a rare side effect, while not causing alarm in investors.