A Study of Orelabrutinib in Patients With Primary Progressive Multiple Sclerosis

Inclusion Criteria: * 18 to 60 years of age, inclusive * Diagnosed with Primary Progressive MS (PPMS) according to 2017 McDonald criteria * Participant must have documented evidence of disability progression observed during the 24 months before screening. * Expanded disability status scale (EDSS) score between 3.0 to 6.5 points, inclusive, at Screening. Exclusion Criteria: * Diagnosed with relapsing-remitting MS (RRMS) or secondary progressive MS (SPMS) * Immunologic disorder other than MS or any other conditions requiring oral, intravenous (IV), intramuscular, or intra-articular corticosteroid therapy. * History or current diagnosis of other neurological disorders that may mimic MS * History of any other significant active medical condition * History of suicidal behavior within 6 months prior to Screening * Any prior history of malignancy if no recurrence within 5 years * Patients on anticoagulation, or antiplatelet therapy will be excluded * Patients took strong/moderate CYP3A inhibitors or strong/moderate CYP3A inducerswithin 14 days * Clinically significant laboratory abnormalities at Screening. * Any allergy, contraindication, or inability to tolerate orelabrutinib or any of the excipients in the study intervention * Vaccination with live or live-attenuated virus vaccine within 1 month prior to Screening * History of alcohol abuse or alcohol use disorder or other drug abuse within 12 months prior to screening.