Participants will be treated for a minimum of 120 weeks in the double-blind phase. Upon positive primary results after the double-blind phase, an optional higher dose extension treatment (OLE phase) is planned for eligible participants. The OLE will be carried out for approximately 96 weeks. Participants will be followed for safety for 48 weeks thereafter. Participants whose B-cell levels still did not replete to their baseline level or the low level of normal (LLN), whichever is lower, will move into the B-cell monitoring (BCM) phase following the safety follow-up phase. The study will end when all participants who were not treated with an alternative B-cell depleting therapy have repleted their B-cells to the baseline value or the lower limit of normal.
This is a randomized, double blind, controlled, parallel group, multicenter study to evaluate efficacy, safety and pharmacokinetics of a higher dose of ocrelizumab per intravenous (IV) infusion every 24 weeks in participants with RMS, in comparison to the approved 600 mg dose of ocrelizumab.