Inclusion Criteria:  Between 10 to <18 years of age (i.e., have not yet had their 18th birthday) at randomization Diagnosis of multiple sclerosis EDSS score of 0 to 5.5, inclusive At least one MS relapse/attack during the previous year or two MS relapses in the previous two years prior or evidence of one or more new T2 lesions within 12 months  Exclusion Criteria:  Participants with progressive MS Participants with an active, chronic disease of the immune system other than MS Participants meeting the definition of ADEM Participants with severe cardiac disease or significant findings on the screening ECG. Participants with severe renal insufficiency