Natalizumab (Tysabri▼): risk of progressive multifocal leukoencephalopathy increases after 2 years of therapy

The risk of developing progressive multifocal leukoencephalopathy (PML) with natalizumab increases after 2 years of therapy. Patients with multiple sclerosis should be informed of the risk before treatment, and again after 2 years. The risk of developing PML beyond 3 years of treatment is currently unknown. Product information for healthcare professionals and patients is being updated with the latest information.