By Thomas Gryta, Of DOW JONES NEWSWIRES
NEW YORK -(Dow Jones)- Biogen Idec Inc. (BIIB) disclosed three more cases of a rare brain infection in multiple sclerosis patients on Tysabri, which it sells with Elan Corp. (ELN), bringing the total number of cases to 49 as of May 6.
The Cambridge, Mass., biotech company reported no additional deaths in patients that have developed progressive multifocal leukoencephalopathy, or PML, bringing the total to 11.
Tysabri is considered a highly effective therapy for MS, and its growth is important to the future of both Elan and Biogen. But its sales have been slower than originally hoped due to concerns about the risk of PML that led to its temporary withdrawal beginning in 2005.
The overall global rate is about 0.7 per 1,000 patients, the company said, which falls within the 1-in-1,000 rate previously seen in clinical trials and implied on the drug’s label.
Shares of Biogen recently traded down 2.9% to $49.92, while Elan shares dropped 1.4% to $6.26.
Of the total cases, 19 were in the U.S., 27 were in the European Union and three were in other areas. Biogen provides monthly updates on the number of PML cases.
The number of cases is important because if the infection rate climbs too high, sales of the drug may drop.
The most recent update translates to a rate of 1.14 cases per 1,000 for patients on the drug for a year or longer, but rises to 1.62 per 1,000 for those on the drug for two years or longer.