Patient were screened, signed an informed consent at visit 1, at the 2nd visit, all patient received a baseline infusion of Natalizumub and subsequently randomized to one of 3 treatment arms. At the randomization visit, the Washout Phase started, and eligible patients were randomized 1:1:1 to one of three treatment groups:
* 8-week washout (8 weeks no treatment) followed by 24 weeks of treatment with fingolimod,
* 12-week washout (8 weeks no treatment and 4 weeks placebo) followed by 20 weeks of treatment with fingolimod, or
* 16-week washout (8 weeks no treatment and 8 weeks placebo) followed by 16 weeks of treatment with fingolimod.
