The study was withdrawn for business reasons. The decision to stop the TECNERGY study was not a result of any safety or efficacy concerns.

The primary objective of this study is to determine whether dimethyl fumarate (DMF) taken over 12 months is effective in reducing Multiple Sclerosis (MS)-related fatigue, as measured by mean changes in the Fatigue Scale for Motor and Cognitive Functions (FSMC), in participants with relapsing-remitting multiple sclerosis (RRMS). The secondary objectives of this study are: To investigate changes from Baseline in FSMC and fatigue severity (Fatigue Severity Scale [FSS]) at 1, 3, 6, 9, and 12 months in participants receiving DMF; To assess the impact of DMF on patient-reported outcomes (PROs), including work productivity (Work Productivity and Activity Impairment-Multiple Sclerosis questionnaire [WPAI-MS]), health-related quality of life (Short Form Health Survey [SF-12]), depression (Beck Depression Inventory-Fast Screen [BDI-FS]), and sleepiness (Epworth Sleepiness Scale [ESS]) at 6 and 12 months in participants receiving DMF; To examine whether an association exists between fatigue and baseline demographics (e.g., age and sex) and disease characteristics (e.g., disease duration, baseline disease activity, treatment history, expanded disability status scale [EDSS] score, and PROs); To assess any changes in fatigue-related medication use.

Key Inclusion Criteria:

• Have a confirmed diagnosis of RRMS and satisfies the therapeutic indication as described in the local label.
• Have a stable EDSS (as assessed by the Investigator) and been on the same (type and dosage) standard of care (SOC) first-line treatment for at least 6 months.
• If taking antidepressants, amphetamine, modafinil, or fampridine (Fampyra), subject must be assessed as having been clinically stable for at least 3 months prior to the Baseline Visit.
• FSMC total score ≥43 (mild fatigue) at Baseline.
• As perceived by the Investigator, have the ability to comply with all requirements of the study protocol.

Key Exclusion Criteria:

• Diagnosis of major depression, as identified by the Investigator.
• Diagnosis of primary progressive, secondary progressive, or progressive relapsing multiple sclerosis.
• History of malignancy (except for basal cell carcinoma that had been completely excised prior to study entry), severe allergic or anaphylactic reactions or known drug hypersensitivity, abnormal laboratory results indicative of any significant disease, and/or a major disease that would preclude participation in a clinical trial.
• Treatment of MS relapse within 90 days prior to study enrollment.
• History of a positive test result for human immunodeficiency virus, hepatitis C virus antibody, or hepatitis B virus (defined as positive for hepatitis B surface antigen or hepatitis B core antibody.
• Impaired hepatic or renal function, as perceived by the Investigator.
• Any prior treatment with DMF (or other fumarate derivative), total lymphoid irradiation, cladribine, fingolimod, T cell or T-cell receptor vaccination, or any therapeutic monoclonal antibody.
• Current enrollment in any other clinical studies.
• Known to suffer from narcolepsy or another significant sleep disorder.
• Comorbidity that may have an impact on fatigue.
• Other unspecified reasons that, in the opinion of the Investigator or Biogen Idec, make the subject unsuitable for enrollment.

NOTE: Other protocol-defined Inclusion/Exclusion Criteria May Apply