The European Medicines Agency (EMA) has finalised a review of Tysabri (natalizumab) and the risk of progressive multifocal leukoencephalopathy (PML), a rare brain infection caused by the JC virus. The Agency’s Committee for Medicinal Products for Human Use (CHMP) has concluded that the risk of developing PML increases after two years of use of Tysabri although this risk remains low…