Reactions 1350 - 7 May 2011

Prior immunosuppressant use upsTysabri PML risk

A newly identified progressive multifocalleukoencephalopathy (PML) risk factor has been addedto the label for Tysabri [natalizumab] in the US.1

The US FDA has updated the Tysabri label to includeinformation regarding the increased risk of developingPML in patients who have taken immunosuppressants(such as mitoxantrone, azathioprine, methotrexate,cyclophosphamide or mycophenolate) prior to takingTysabri. The Tysabri label already warned of the risksassociated with concurrent use of these medications.

The revised drug label also now contains a table,summarising the relationship between the number ofTysabri infusions received (treatment duration/exposure) and the risk of PML.

The FDA states that, through to 28 February 2011,102 cases of PML were reported among 82 732 patientstreated with Tysabri worldwide.

Anti-JCV antibody status further stratifiesPML risk

The EMA’s CHMP, meanwhile, is recommending thatthe European Tysabri label be updated to include anti-JCvirus (anti-JCV) antibody status as a third factor,* tofurther stratify patients’ risk of PML.2

Tysabri’s manufacturers, Biogen Idec and ElanCorporation, are welcoming this recommendation.Douglas Williams of Biogen Idec says, "we are pleasedthe CHMP has recommended adding anti-JCV antibodystatus as a third important risk factor for PML to theTysabri label. By identifying and understanding themultiple factors that are part of the benefit-risk equation,patients can be informed and empowered to engage in adiscussion with their physician about choosing the righttherapy for their MS."* in addition to treatment duration and prior immunosuppressantuse

1. FDA Drug Safety Communication: Safety update on Progressive MultifocalLeukoencephalopathy (PML) associated with Tysabri (natalizumab). InternetDocument : [2 pages], 22 Apr 2011. Available from: URL: http://www.fda.gov.

2. Biogen Idec, et al. CHMP Recommends Updating TYSABRI Labeling withanti-JC Virus Antibody Status as a Third Factor to Further Stratify Risk of PML.Media Release : 18 Apr 2011. Available from: URL: http://www.biogenidec.com.

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Reactions 7 May 2011 No. 13500114-9954/10/1350-0001/$14.95 © 2010 Adis Data Information BV. All rights reserved