A Study to Evaluate the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Ocrelizumab in Participants With Relapsing Multiple Sclerosis and Primary Progressive Multiple Sclerosis

Inclusion Criteria: * Diagnosis of RMS/PPMS in accordance with the revised 2017 McDonald Criteria * EDSS score from 0-5.5 (RMS) or 3.0-6.5 (PPMS), inclusive, at screening and baseline * Documented MRI of brain with abnormalities consistent with MS before screening Exclusion Criteria: * Diagnosis of PPMS or non-active secondary progressive multiple sclerosis (SPMS) (only for RMS cohort) * History of relapsing remitting multiple sclerosis (RRMS) or SPMS at screening (only for PPMS cohort) * Disease duration of more than 10 years in participants with an EDSS ≤ 2.0 at screening (only for RMS cohort) * History of confirmed or suspected progressive multifocal leukoencephalopathy (PML) * Inability to complete an MRI scan or contraindication to Gd administration * Contraindications to mandatory pre-medications (i.e., corticosteroids and antihistamines) * Known presence of other neurologic disorders if they could interfere with the diagnosis of MS or assessments of efficacy and/or safety during the study * Any concomitant disease that may require chronic treatment with systemic corticosteroids or immunosuppressants during the course of the study * Known history of human immunodeficiency virus (HIV) infection * Lack of peripheral venous access * Previous treatment with B-cell targeted therapies (i.e., rituximab, ocrelizumab, atacicept, belimumab, or ofatumumab), unless the last infusion was at least 6 months prior to screening * Positive screening tests for hepatitis B virus (HBV) a…