A Study to Evaluate the Efficacy, Safety and Pharmacokinetics (PK) of a Higher Dose of Ocrelizumab in Adults With Primary Progressive Multiple Sclerosis (PPMS)

Participants will be treated for a minimum of 120 weeks in the double-blind treatment (DBT) phase. Upon positive primary results after the DBT phase, an optional higher dose extension treatment, open-label extension (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 lower limit 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 LLN.