Reactions 1288 - 13 Feb 2010

FDA alerts public over Tysabri linkto PML

The US FDA is alerting the public that patients’ risk ofprogressive multifocal leukoencephalopathy (PML)increases with the number of Tysabri [natalizumab]infusions received.

Approximately 66 000 people worldwide hadreceived ≥ 1 dose of Tysabri between July 2006 and31 December 2009, and 31 confirmed cases of PML(8 fatal) had been received by the FDA as of 21 January2010. The cumulative rates of PML (cases per 1000patients) for ≥ 1, ≥ 12, ≥ 24 and ≥ 30 infusions of Tysabriwere reported as 0.3, 0.5, 0.8 and 0.5, respectively, inthe US, and 0.7, 1.1, 1.9, and 1.8 cases outside of theUS. As the number of patients who have received ≥ 36infusions is reportedly limited, adverse-event rates areunable to be well characterised for this dose group. TheFDA stated that there have been no reports of PML inpatients who had received Tysabri for < 12 monthssince June 2006.

Safety information regarding the risks of PML withincreased exposure to Tysabri will now be included inthe Tysabri drug label and the patient Medication Guide.In addition, the ‘Warnings and Precautions’ section ofthe drug label has been updated to inform healthcareprofessionals that patients who develop PML anddiscontinue Tysabri have been known to subsequentlydevelop immune reconstitution syndrome.FDA. FDA drug safety communication: risk of progressive multifocalleukoencephalopathy (PML) with the use of Tysabri (natalizumab). InternetDocument : [2 pages], 5 Feb 2010. Available from: URL: http://www.fda.gov 801108676

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Reactions 13 Feb 2010 No. 12880114-9954/10/1288-0001/$14.95 © 2010 Adis Data Information BV. All rights reserved