Reactions 1290 - 27 Feb 2010

■ Biogen Idec and Elan have announced four newcases of progressive multifocal leukoencephalopathy(PML) in patients receiving Tysabri (natalizumab),taking the total number of cases up to 35. Earlier thismonth, the US FDA announced that labelling forTysabri would be updated, after data (from the31 cases confirmed at the time) suggested that the riskof PML increases with the number of Tysabri infusionsreceived.* As of 9 February, eight cases of PML hadbeen fatal. Biogen’s spokesperson Naomi Aoki statesthat the drugs labelling indicates an infection rate of1 in 1000. The overall picture, including the newcases, is consistent with the rate described in thelabel.

* see Reactions 1288 p4; 801108676

Biogen Idec Inc. Biogen, Elan’s Drug Linked to 35 Brain-Disease Cases(Update1). Media Release : 16 Feb 2010. Available from: URL: http://www.biogenidec.com 809109627

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