The primary objective of the study is to evaluate relapse activity, as measured by the proportion of participants relapsed at 12 months, in participants with relapsing-remitting multiple sclerosis (RRMS) who transition from Tysabri (BG00002) to Tecfidera (BG00012) in the real-world setting. The secondary objective is to further evaluate relapse activity, defined as annualized relapse rate (ARR), hospitalization and intravenous corticosteroid use, during the first year of Tecfidera treatment following transition from Tysabri treatment.

The study period will consist of a single time point retrospective medical chart abstraction with no required study visits or procedures. Data collection for this study is expected to last up to approximately five months.

Key Inclusion Criteria:

• Diagnosis of RRMS per McDonald criteria
• Received at least 12 months of continuous treatment with Tysabri monotherapy prior to initiation of Tecfidera. Note: continuous treatment with Tysabri is defined as treatment uninterrupted by other disease-modifying treatment.
• Initiated treatment with Tecfidera at least 12 months prior to enrollment into the study
• Patient has sufficient available medical records for data abstraction to meet the objectives of the study

Key Exclusion Criteria:

• Diagnosed with a progressive form of multiple sclerosis (MS) (progressive-relapsing, primary progressive, secondary progressive)
• Received treatment with any of the following after discontinuation of Tysabri and before initiation of treatment with Tecfidera (i.e., during washout period): interferon-beta, glatiramer acetate, fingolimod, teriflunomide, rituximab, alemtuzumab, ocrelizumab or any investigational compound for the treatment of RRMS
• Received BG00012, or other formulations of dimethyl fumarate, or Fumaderm® or compounded fumarates at any time prior to initiation of treatment with Tecfidera
• History of progressive multifocal leukoencephalopathy (PML) while on Tysabri or within 6 months of discontinuing treatment with Tysabri

NOTE: Other protocol-defined inclusion/exclusion criteria may apply

Participants with a diagnosis of RRMS receiving at least 12 months of continuous treatment with Tysabri monotherapy prior to initiation of Tecfidera. Additionally, participants must have initiated treatment with Tecfidera at least 12 months prior to enrollment into the study.