Proof-of-concept Study for SAR441344 (Frexalimab) in Relapsing Multiple Sclerosis

Inclusion criteria:

1. Participant must be 18 to 55 years of age inclusive, at the time of signing the informed consent.
2. The participant must have been diagnosed with RMS (relapsing-remitting MS and secondary progressive MS participants with relapses) according to the 2017 revision of the McDonald diagnostic criteria.
3. The participant must have at least 1 documented relapse within the previous year, or ≥2 documented relapses within the previous 2 years, or ≥1 active Gd-enhancing brain lesion on an MRI scan in the past 6 months and prior to screening.
4. Body weight within 45 to 120 kg (inclusive) and body mass index (BMI) within the range 18.0 to 35.0 kg/m2 (inclusive) at Screening.
5. Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
6. Capable of giving signed informed consent.

Exclusion criteria:

1. The participant has been diagnosed with PPMS according to the 2017 revision of the McDonald diagnostic criteria or with non-relapsing SPMS.
2. The participant has conditions or situations that would adversely affect participation in this study.
3. The participant has a history of or currently has concomitant medical or clinical conditions that would adversely affect participation in this study.
4. History, clinical evidence, suspicion or significant risk for thromboembolic events, as well as myocardial infarction, stroke and/or antiphosholipid syndrome and any participants requiring antithrombotic treatment.
5. Allergies to humanized monoclonal antibodies or severe post-treatment hypersensitivity reactions other than localized injection site reaction, to any biological molecule.
6. The participant has received any of the forbidden medications/treatments within the specified time frame before any baseline assessment.
7. The participant has taken other investigational drug within 3 months or 5-half-live, whichever is longer, before the screening visit.
8. The participant has an EDSS score >5.5 at the first screening visit.
9. The participant has had a relapse in the 30 days prior to randomization.
10. Positive human immunodeficiency virus (HIV) serology (anti HIV1 and anti HIV2 antibodies) or a known history of HIV infection, active or in remission.
11. Abnormal laboratory test(s) at Screening.
12. Presence of Hepatitis B surface antigen (HBsAg) or anti-Hepatitis B core antibodies (anti-HBc Ab) at screening or within 3 months prior to first dose of study intervention.
13. Positive Hepatitis C antibody test result at screening or within 3 months prior to starting study intervention.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.