Primary Progressive Multiple Sclerosis (PPMS) Study of Bruton's Tyrosine Kinase (BTK) Inhibitor Tolebrutinib (SAR442168) (PERSEUS)

Inclusion Criteria: * 18 to 55 years of age inclusive * Diagnosis of PPMS according to the 2017 McDonald criteria * Expanded disability status scale (EDSS) score between 2.0 to 6.5 points, at screening inclusive * Positive cerebrospinal fluid oligoclonal bands and/or elevated Immunoglobulin G (IgG) index either during screening or documented previous history. * Contraceptive use consistent with local regulations for individuals participating in clinical studies * Participant is eligible to participate if she is not pregnant or breastfeeding, and at least one of the following conditions applies: * Is not a woman of childbearing potential (WOCBP) or is a WOCBP and agrees to use an acceptable contraceptive method * the participant must not have access to ocrelizumab (eg, ocrelizumab not available on the national market or not reimbursed for the approved indication). * the participant must have access to and be eligible to be treated with ocrelizumab but: 1) does not tolerate it due to side effects or safety reasons; and/or 2) has failed ocrelizumab treatment due to perceived lack of efficacy Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * Participant has conditions that would adversely affect study participation such as short life expectancy. * Evidence of infection with human immunodeficiency virus (HIV), transplantation, progressive multifocal leukoencephalopathy (PML), active hepatitis B or C, active or latent tuberculosis or other active infection that would adversely affect study participation. * Persistent chronic or active or recurring system infection that may adversely affect participation or IMP administration in this study as judged by the investigator * History of malignancy within 5 years prior to screening. * History of alcohol or drug abuse within 1 year prior to Screening. * Hospitalized for psychiatric disease within 2 years prior to Screening. * Clinically significant laboratory abnormalities (including evidence of liver injury) or electrocardiogram abnormalities at Screening. * A bleeding disorder or known platelet dysfunction at any time prior to the screening visit. * A platelet count \<150 000/μL at the screening visit. * A history of significant bleeding event within 6 months prior to screening, according to the Investigator's judgment such as, but not limited to cerebral or gastrointestinal * Lymphocyte count below the lower limit of normal at Screening. * Recent live (attenuated) vaccine within 2 months before the first treatment visit. * Recent major surgery (within 4 weeks of Screening) or planned major surgery during the study. * The participant has received medications/treatments for MS within a specified time frame. * Receiving potent and moderate inducers of cytochrome P450 3A (CYP3A) or potent inhibitors of CYP2C8 hepatic enzymes. * Receiving anticoagulant or antiplatelet therapy (such as aspirin \>81mg/day, clopidogrel, warfarin). * Contraindications to magnetic resonance imaging (MRI). NOTE: Other Inclusion/Exclusion criteria may apply. The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial