Tysabri natalizumab: Post-marketing study data

As of Nov. 30, 2009, Biogen Idec said that there have been 28 confirmed cases of progressive multifocal leukoencephalopathy (PML) in patients receiving Tysabri monotherapy for MS since the drug was relaunched in the U.S. and its first international approval in 2006. At Sept. 30, 2009, Biogen Idec reported that 60,700 patients had been treated with Tysabri in the post-marketing setting. In September, FDA reported 13 confirmed cases of PML in patients receiving Tysabri monotherapy for MS as of Sept. 8, and that the risk for developing PML appears to increase with the number of Tysabri infusions received (see BioCentury, Sept. 28, 2009). ...