A Phase III Multicenter, Randomized, Double-Blind, Double-Dummy, Parallel-Group Study To Evaluate The Efficacy And Safety Of Fenebrutinib Compared With Ocrelizumab In Adult Patients With Primary Progressive Multiple Sclerosis.

• A diagnosis of PPMS in accordance to the revised 2017 McDonald Criteria (Thompson et al. 2018).

• Disability progression in the 12 months prior to screening.

• Expanded Disability Status Scale (EDSS) score from 3.0 to 6.5 inclusive at screening.

• Pyramidal functional subscore >=2 at screening.

• For participants currently receiving proton pump inhibitors (PPIs), H2-receptor antagonists (H2RAs), symptomatic treatment for Multiple Sclerosis (MS) (e.g. fampridine, cannabis) and/or physiotherapy: treatment at a stable dose during the screening period prior to the initiation of study treatment and plans to remain at a stable dose for the duration of study treatment.

• Ability to complete the 9-Hole Peg Test (9-HPT) for each hand in <240 seconds.

• Ability to perform Timed 25-Foot Walk Test (T25FWT) in <150 seconds.

• For female participants of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures, and refrain from donating eggs.

• For male participants: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures, and refrain from donating sperm.