PERSEUS

The purpose of the study is to see if the study drug, SAR442168, works to delay the progression of disability in people with PPMS compared to placebo and has an acceptable safety profile.

Inclusion Criteria

• The participant must have a current diagnosis of PPMS in accordance with the 2017 revised McDonald criteria.
• The participant must have an EDSS score at screening from 2.0 to 6.5 points, inclusive.
• The participant must have positive CSF (isoelectric focusing evidence of oligoclonal bands and/or elevated IgG index) either during screening or previous historical assessment. Supportive source documentation must be available

Exclusion Criteria

• A history of T-lymphocyte or T-lymphocyte-receptor vaccination, transplantation (including solid organ, stem cell, and bone marrow transplantation) and/or antirejection therapy.
• The participant has received any live (attenuated) vaccine (including but not limited to varicella zoster, oral polio, and nasal influenza) within 2 months before the first treatment visit.
• The participant has a lymphocyte count less than the lower limit of normal (LLN) at the Screening Visit.

Study Requirements

We expect you to be in study for 18-24 months. The study visits would be monthly for first 6 months, after that the visits would be alternate month up to one year followed by quarterly visits. The investigational drug is an orally administered, small molecule. Blood sample would be collected every visit. Questionnaires and rater scales would be collected every visit. MRI would be performed every 3 months until the study ends.