A Study to Learn About the Safety of Diroximel Fumarate (DRF) and Dimethyl Fumarate (DMF) and Their Effects on Relapses in Pediatric Participants With Relapsing Forms of Multiple Sclerosis (RMS)

The primary objectives of this study are to evaluate the safety, tolerability of diroximel fumarate (DRF), the noninferiority of the clinical efficacy of monomethyl fumarate (MMF) (pooled DRF and dimethyl fumarate \[DMF\] treatment) compared to that of fingolimod and long-term safety and tolerability of DRF in participants who completed Week 96 of the Treatment Period. The secondary objectives of this study are to characterize the pharmacokinetic (PK) profile of DRF metabolites (MMF and 2-hydroxyethyl succinimide \[HES\]), additional safety and tolerability of DRF, noninferiority of the radiological efficacy of MMF (pooled DRF and DMF treatment) compared to that of fingolimod, and to further describe the safety and long-term multiple sclerosis (MS) outcomes of DRF in participants who completed Week 96 of the Treatment Period.