Key Inclusion Criteria:  Must have a diagnosis of RMS, as defined by revised 2017 McDonald's criteria. Expanded Disability Status Scale (EDSS) score between 0.0 and 5.0, inclusive, at screening and baseline (Visit 1). Neurologically stable with no evidence of relapse within 30 days prior to baseline (Visit 1). For Japanese participants: Born in Japan and biological parents and grandparents were of Japanese origin. If previously lived outside of Japan for more than 5 years, must not have had a significantly modified diet since leaving Japan. For Chinese participants: Born in China, and biological parents and grandparents were of Chinese origin. If previously lived outside of China for more than 5 years, must not have had a significantly modified diet since leaving China.  Key Exclusion Criteria:  Has a multiple sclerosis (MS) relapse that has occurred within the 30 days prior to randomization and/or the participant has not stabilized from a previous relapse prior to randomization. History of severe allergic or anaphylactic reactions or of any allergic reactions that, in the opinion of the investigator, are likely to be exacerbated by any component of the study treatment. History of, or ongoing, malignant disease, including solid tumors and hematologic malignancies. History of systemic hypersensitivity reaction to DRF, dimethyl fumarate (DMF), MMF or other fumaric esters, the excipients contained in the formulation, and if appropriate, any diagnostic agents to be administered during the study. Evidence of current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within 14 days prior to Screening, between screening and baseline visit, or at baseline visit, including but not limited to a fever (temperature >37.5 degrees Celsius [°C]), new and persistent cough, breathlessness, or loss of taste and/or smell. Have close contact within 14 days prior to Day 1 with a SARS-CoV-2 positive individual. History or positive test result at screening for human immunodeficiency virus (HIV). Current enrollment or a plan to enroll in any interventional clinical study in which an investigational treatment or approved therapy for investigational use is administered within 30 days prior to baseline (Visit 1) or 5 half-lives, whichever is longer. Previous participation in this study or previous studies with DRF, DMF, or MMF. Has a clinically significant history of suicidal ideation or suicidal behavior occurring in the past 12 months as assessed by the C-SSRS at Screening.  NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.