Additional Relevant Details This positive opinion follows April 2016 EC approvals that granted TYSABRI unlimited validity for the marketing authorization in Europe and updated the European Union product information and physician/patient education materials. The new patient management plan provides an updated risk algorithm which allows physicians to have more individualized benefit-risk discussions with their patients and provides them with clear guidelines to manage their patients appropriately.According to the EMA, the updated risk estimates show that the risk of developing progressive multifocal leukoencephalopathy (PML) is small, and lower than previously estimated, at antibody index values of 0.9 or less, and increases substantially in patients with index values above 1.5 who have been treated with TYSABRI for longer than two years. In patients who tested negative for JC virus antibodies, the PML risk estimate remains unchanged at 0.1 per 1,000 patients. Biogen is committed to patient safety and continues to work closely with the scientific community to provide greater clarity on the minimization of risk for patients taking TYSABRI.