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

Primary Objective:

To determine the efficacy of SAR441344 as measured by reduction of the number of new active brain lesions

Secondary Objective:

* To evaluate efficacy of SAR441344 on disease activity as assessed by other MRI measures
* To evaluate the safety and tolerability of SAR441344
* To evaluate pharmacokinetics of SAR441344

The duration of each participant will be no longer than 320weeks in both parts of the study, including 4 weeks of screening, at maximum 292 weeks of treatment and 24 weeks of follow-up.

Eligibility Criteria:
Inclusion criteria:

* Participant must be 18 to 55 years of age inclusive, at the time of signing the informed consent.
* 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.
* 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.
* 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.
* Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
* Capable of giving signed informed consent.

Exclusion criteria:

* The participant has been diagnosed with PPMS according to the 2017 revision of the McDonald diagnostic criteria or with non-relapsing SPMS.
* The participant has conditions or situations that would adversely affect participation in this study.
* The participant has a history of or currently has concomitant medical or clinical conditions that would adversely affect participation in this study.
* 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.
* Allergies to humanized monoclonal antibodies or severe post-treatment hypersensitivity reactions other than localized injection site reaction, to any biological molecule.
* The participant has received any of the forbidden medications/treatments within the specified time frame before any baseline assessment.
* The participant has taken other investigational drug within 3 months or 5-half-live, whichever is longer, before the screening visit.
* The participant has an EDSS score \>5.5 at the first screening visit.
* The participant has had a relapse in the 30 days prior to randomization.
* Positive human immunodeficiency virus (HIV) serology (anti HIV1 and anti HIV2 antibodies) or a known history of HIV infection, active or in remission.
* Abnormal laboratory test(s) at Screening.
* 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.
* 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.