REbif FLEXible Dosing in Early Multiple Sclerosis (MS)

The study is a 24 months randomized, double-blind, Placebo-controlled, multi-center clinical trial with an optional 12 months open label extension. The primary objective of the study is to evaluate the effect of fetal bovine serum \[FBS\]-free/human serum albumin \[HSA\]-free formulation of Interferon \[IFN\] beta-1a (RNF) 44 microgram (three times weekly and once weekly) versus placebo on the time to conversion to McDonald multiple sclerosis (MS) criteria (2005) in subjects with a first clinical demyelinating event at high risk of converting to MS. The main secondary objective of study is to evaluate the effect of RNF 44 microgram (three times weekly and once weekly) versus placebo on the "Time to conversion to clinically definite MS (CDMS)" in subjects with a first clinical demyelinating event at high risk of converting to MS. At the end of 24 month double-blind core REFLEX trial, subjects who will not convert to CDMS and decide to receive open-label (OL) treatment will be enrolled into an open-label, 12 month extension period to evaluate the effect of RNF 44 mcg three times weekly treatment on the time to conversion to McDonald MS and time to conversion to CDMS.