Quoted from http://www.boston.com/business/healthcare/articles/2010/02/06/federal_regulators_post_safety_update_on_tysabri//
Tysabri safety update posted
Label warns that infection risk increases with use
By Robert Weisman
Globe Staff / February 6, 2010
Federal regulators yesterday posted a safety update to doctors and patients confirming changes made to the label of Tysabri, a popular treatment for relapsing multiple sclerosis. The drug is made and comarketed by Cambridge biotechnology company Biogen Idec Inc.
The label now includes a warning that the risk of a rare brain infection called progressive multifocal leukoencephalopathy increases with longer use of Tysabri, according to the posting by the Food and Drug Administration. The FDA said there have been 31 confirmed cases of the infection, eight of which have been fatal, since July 2006, when Tysabri was reintroduced after being pulled from the market for two years. But the infection remains extremely rare, within the range stated on the label of one case per 1,000 patients. Many multiple sclerosis patients have said the drug dramatically reduces debilitating flare-ups of their symptoms.
“Based on the available information, FDA believes that the clinical benefits of Tysabri continue to outweigh the potential risks,’’ the regulatory agency said in its safety update yesterday.
Biogen Idec spokeswoman Naomi Aoki said the new label went into use in November in the United States and in January in Europe after company officials approached regulators on both continents about modifying the label to reflect the risks of long-term use.