FDA warns of progressive multifocal leukoencephalopathy (PML) risk with Tysabri

The FDA continues to receive reports of progressive multifocal leukoencephalopathy (PML) in patients treated with Tysabri (natalizumab, from Biogen Idec). Since its launch in July 2006, 13 confirmed cases of Tysabri-related PML have been reported worldwide in patients treated with Tysabri monotherapy for multiple sclerosis (MS). Of these, four cases were in the U.S. There have been no postmarketing reports of PML in patients treated with Tysabri for Crohn's disease. The risk for developing PML appears to increase with the number of Tysabri infusions received. The number of monthly infusions for Tysabri in the 13 patients who developed PML range from 12–35 infusions (average: 25 infusions).

At this time, the FDA is not requiring changes regarding PML to the Tysabri Prescribing Information or the Tysabri risk management plan, TOUCH Prescribing Progam.

Tysabri is indicated in moderately-to-severely active Crohn's disease in adult patients who have had inadequate response to or are intolerant to conventional therapy and TNF-α inhibitors and for the treatment of relapsing forms of MS.

For more information visit www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm182667.htm.