FDA Advises Healthcare Providers on Tysabri Risk

The FDA has issued a MedWatch informing healthcare professionals of two cases of progressive multifocal leukoencephalopathy (PML) in European patients receiving Biogen Idec and Elan’s multiple sclerosis (MS) treatment Tysabri as a monotherapy.

Prescribing information for Tysabri (natalizumab) will be revised to include information telling prescribers and patients that cases of PML have occurred in patients taking Tysabri as monotherapy, according to the FDA. In addition, healthcare professionals should continue to monitor patients for signs and symptoms of PML.

Last month, the European Medicines Agency said it was assessing the PML cases after Biogen Idec reported them in a July 31 SEC filing. The condition, a rare brain infection, is a known side effect of Tysabri and led to the product’s withdrawal in 2005.

Tysabri was reintroduced in 2006 under a restricted distribution program and is available only to patients with relapsing MS or Crohn’s disease who are enrolled in the risk-minimization plan called the TOUCH Prescribing Program. Every Tysabri-treated patient is closely monitored under the program and followed for the possible occurrence of PML and other serious opportunistic infections.

Previous PML cases were seen in MS patients who took the drug in combination with other immunomodulatory therapies. The FDA still says Tysabri monotherapy may confer a lower risk of PML than when the drug is used together with other immunomodulatory medications.