Study of the Effect of BG00012 on MRI Lesions and Pharmacokinetics in Pediatric Subjects With RRMS

Key Inclusion Criteria: * Ability of parents or legal guardians to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information in accordance with national and local subject privacy regulations. Subjects will provide assent in addition to the parent or legal guardian, as appropriate, as per local regulations. * Must have a body weight of ≥30 kg at Screening and Day 1. * Must have a diagnosis of RRMS according to McDonald criteria for MS (2010) \[Polman 2011\] and International Pediatric Multiple Sclerosis (MS) Study Group criteria for pediatric MS (2013) \[Krupp 2013\]. Key Exclusion Criteria: * Primary progressive, secondary progressive, or progressive relapsing MS (as defined by \[Lublin and Reingold 1996\]). These conditions require the presence of continuous clinical disease worsening over a period of at least 3 months. Subjects with these conditions may also have superimposed relapses but are distinguished from relapsing-remitting subjects by the lack of clinically stable periods or clinical improvement. * Disorders mimicking MS, such as other demyelinating disorders (e.g., acute disseminated encephalomyelitis), systemic autoimmune disorders (e.g., Sjögren disease, lupus erythematosus, and neuromyelitis optica), metabolic disorders (e.g., dystrophies), and infectious disorders. * History of severe allergic or anaphylactic reactions or known drug hypersensitivity to dimethyl fumarate or fumaric acid esters. NOTE: Other protocol-defined inclusion/exclusion criteria may apply.