FDA details timeframe of Tysabri’s PML risk

The brain infection risk from Biogen Idec’s multiple sclerosis drug Tysabri appears highest during the third year of treatment, U.S. health officials said in an updated warning released on Friday.

The potentially fatal infection, known as progressive multiform leukoencephalopathy (PML), occurs in an estimated 1.5 per 1,000 patients treated with Tysabri during months 25 to 36, the Food and Drug Administration said.

The FDA said it was the first time it had estimated the chances of PML for specific time intervals rather than providing a cumulative risk over years.

• Caroline says: Biogen's billion-dollar drug Tysabri has been a miracle drug for many, many MS patients -- but it has not been without risk of developing PML, a potentially deadly brain infection. The FDA has now released a timeline of when patients are most likely to develop PML -- the risk is highest in year 3 of treatment. Tysabri's label was recently updated in the US to include the risk of PML.
   

• Related Links:
• http://www.reuters.com/article/2011/04/22/us-biogen-tysabri-idUSTRE73L2WN2011042…

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