The study is divided into a Core Part and Extension Part. The Core Part is a 24-month, double-blind, triple dummy, randomized, 3-arm active-controlled in children/adolescent patients aged 10-17 years old with Multiple Sclerosis (MS). The Extension Part is 60-month (5 year) open label (except for first 12 weeks transition which will remain double-blind) treatment for patients who complete the Core Part of the study and meet all inclusion/exclusion criteria. The targeted enrollment is 120 participants with multiple sclerosis which will include at least 5 participants with body weight (BW) ≤40 kg and at least 5 participants with age 10 to 12 years in each of the ofatumumab and siponimod arms. There is a minimum 6 month follow up period for all participants (core and extension). Total duration of the study could be up to 7 years.
