Key Inclusion Criteria:

1. Must have a baseline (pre-dose on Day 1) Expanded Disability Status Scale (EDSS) between 0.0 and 5.0, inclusive.
2. Must have experienced at least 1 documented relapse within the 12 months before screening, with a prior brain magnetic resonance imaging (MRI) demonstrating lesion(s) consistent with MS or have showed evidence of GdE lesion(s) of the brain on an MRI performed within the 6 weeks prior to screening.

Key Exclusion Criteria:

1. An MS relapse that occurred within the 30 days prior to screening and/or the participant has not stabilized from a previous relapse prior to screening.
2. Current hepatitis C infection and current hepatitis B infection. Participants with immunity to hepatitis B from previous natural infection or vaccination are eligible to participate in the study.
3. 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.
4. History or positive test result at screening for human immunodeficiency virus (HIV).
5. Use at the time of enrollment and/or anticipated ongoing use of any traditional and/or unlicensed medicines and/or traditional therapies and/or herbal preparations, which are known or considered by the Investigator to affect MS and endpoints that are being considered in the study, including safety and efficacy.
6. Current enrollment in any other investigational drug study or participation in any other investigational study within 6 months prior to screening.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.