Study to Explore the Onset of Efficacy on Magnetic Resonance Disease Activity of BG00012 (Dimethyl Fumarate) in Patients With Relapsing remitTing Multiple Sclerosis

Key Inclusion Criteria: * Participants with RRMS (McDonald criteria, 2010) who do not accept current injectable firstline DMTs. * Multiple sclerosis (MS) onset within one year before enrolment * ≥ 1 Gd+ lesions at a brain MRI scan performed within three months beforeenrolment. * No previous disease modifying and/or immunosuppressive treatments for MS. * Must have a baseline EDSS between 0.0 and 5.0, inclusive. · Women of childbearing potential (i.e. who are not post-menopausal for at least 1 year) and men must practice effective contraception (as defined by the Investigator) during the study and be willing and able to continue contraception for 30 days after their last dose of study treatment. Exclusion Criteria: * Primary progressive, secondary progressive, or progressive relapsing MS, as defined by Lublin and Reingold (Lublin and Reingold 1996) * Previous disease modifying and/or immunosuppressive treatments for MS, including Tcell or T-cell receptor vaccination, any therapeutic monoclonal antibody, Mitoxantrone, Cyclophosphamide * Previous treatment with Fumaderm®, dimethyl fumarate or other fumarates * History of malignancy (except basal cell carcinoma that has been completely excised prior to study enrollment) * History of severe allergic or anaphylactic reactions or known drug hypersensitivity.Known allergy/hypersensitivity to Gadolinium. * History of abnormal laboratory results indicative of any significant endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, renal, and/or other major disease that in the opinion of the Investigator would preclude participation in a clinical trial. * History of or positive test result at screening for human immunodeficiency virus (HIV).Positive for hepatitis C antibody and/or positive for hepatitis B surface antigen (HBsAg) at screening. * History of drug or alcohol abuse (as defined by the Investigator) within the 2 years prior to inclusion. * An MS relapse that has occurred within the 30 days prior to inclusion (screening) AND/OR the subject has not stabilized from a previous relapse prior to inclusion. NOTE: Other protocol-defined inclusion/exclusion criteria may apply.