CAMBRIDGE, Mass. (AP) — Biogen Idec Inc. said late Friday a ninth Tysabri patient developed a potentially deadly brain infection since the drug was reintroduced to the market in 2006.
The drug, which treats multiple sclerosis, was pulled from the market in 2005 following occurrences of a rare, but deadly, brain infection called progressive multifocal leukoencephalopathy. The drug was reintroduced in July of 2006, with restrictions and a monitoring program.
Concerns over additional cases of the rare disease have been weighing down sales of the drug for more than a year. Still, the company has backed the risk profile and said physicians have become more comfortable with the potential side effects.
Since the drug was reintroduced, about 24,900 patients have received at least one year of therapy, with 14,400 receiving 18 months of therapy and 6,800 with 2 years of therapy. In all, there were about 40,000 patients on the drug at the end of March, with 20,800 in the U.S.