The duration of each participant will be no longer than 176 weeks in both parts of the study, including 4 weeks of screening, at maximum 148 weeks of treatment and 24 weeks of follow-up.
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