Kapoor R, Ho PR, Campbell N, Chang I, Deykin A, Forrestal F, Lucas N, Yu B, Arnold DL, Freedman MS, Goldman MD, Hartung HP, Havrdov? EK, Jeffery D, Miller A, Sellebjerg F, Cadavid D, Mikol D, Steiner D. Effect of natalizumab on disease progression in secondary progressive multiple sclerosis (ASCEND): a phase 3, randomised, double-blind, placebo-controlled trial with an open-label extension. Lancet Neurol. 2018 05; 17(5):405-415.