As reported in Reuter's on Friday, Biogen acknowledged that 6 new cases of progressive multifocal leukoencephalopathy (or PML) occurred in December bringing the total now to 85 reported cases. Of the 85 cases of PML reported, 16 patients have died, while 69 are still alive with varying degrees of disability.
Biogen temporarily withdrew Tysabri from the market in 2005 after it was first associated with the condition; it was brought back, with stricter safety warnings, in 2006.The drug is widely considered the most effective on the market, but its sales have been crimped by concerns over PML. The risk of the condition increases with the length of treatment.After two years of monthly infusions, the incidence of PML is now 2.13 per 1,000 patients.
The overall rate of PML in clinical trials was 1 in 1000, a benchmark that has now been exceeded. Biogen is developing a test that it hopes will allow doctors to screen patients to identify which might be more likely to develop PML. Biogen shares were down $2.02 or 2.9 percent on the news.
Posted by Bruce Lehr Jan 23rd 2011.