The purpose of each study is to independently measure the annualized relapse rate (ARR) with administration of frexalimab compared to a daily oral dose of teriflunomide in male and female participants with relapsing forms of multiple sclerosis (aged 18 to 55 years at the time of enrollment). People diagnosed with relapsing forms of multiple sclerosis are eligible for enrollment as long as they meet all the inclusion criteria and none of the exclusion criteria. Study details include: * This event-driven study will have variable duration depending on the recruitment rate, the event rate, the study discontinuation rate and the 12-month minimum treatment duration. Different participants will have different study durations. The last participant randomized will have at least 12 months of study duration, and assuming a 28-month recruitment period, the first participant randomized will have 40 months or longer of study duration. * The study intervention duration will vary similarly as the study duration. * The assessment of scheduled visits will include 1 common end of study \[EOS\] visit and 3 follow-up visits) with a visit frequency of every 4 weeks for the first 6 months and then every 3 months.