Quoted from http://boston.bizjournals.com/boston/stories/2010/01/18/daily32.html
Biogen optimistic despite more PML casesBoston Business Journal - by Julie M. Donnelly
Biogen Idec officials said Wednesday three more patients have contracted a rare brain infection associated with the company’s multiple sclerosis drug, Tysabri.
However, the Cambridge-based biotechnology company says the additional cases do not impact the overall safety profile for the medication.
The total number of cases of progressive multifocal leukoencephalopathy, or PML, since July 2008 now stands at 31.
More than 60,000 patients have taken Tysabri since the drug’s reintroduction in July 2006, and the incidence of PML is currently .47 cases per 1,000 patients. Tysabri’s warning labels said the anticipated incidence rate of PML is 1 in 1,000 rate.
The company took Tysabri off the market between February 2005 and July 2006 because of concerns about the risk of PML.
Since the risks of contracting PML increases the longer a patient takes the drug, the number of PML cases is expected to rise. So far, 19 cases have been detected in Europe, 10 cases in the United States. Two other cases have been detected elsewhere, according to Biogen officials.