A 2-year randomized, 3-arm, double-blind, non-inferiority study comparing the efficacy and safety of ofatumumab and siponimod versus fingolimod in pediatric patients with multiple sclerosis followed by an open-label extension

* ofatumumab (oMB157) as solution for injection in an autoinjector * Siponimod (BaF312) as film-coated tablet * Fingolimod (FTY720) as film-coated capsules The study is intended to randomize approximately 180 participants in a 1:1:1 randomization allocation ratio (60 participants randomized to s.c. ofatumumab, 60 participants to oral siponimod and 60 participants to oral fingolimod). efficacy assessments are: MS relapse, eDSS, MRi, neurofilament light chain, Symbol Digit Modalities Test (SDMT), and B-Cell blood Safety assessments are: Physical examination (including skin), Height and weight, ophthalmologic examination including optical Coherence Tomography (oCT), Pulmonary function tests (PFTs), Vital signs Laboratory evaluations, electrocardiogram (eCG), Columbia Suicide Severity Rating Scale (C-SSRS) The primary objective of the study is to demonstrate that ofatumumab and/or siponimod are no worse (i.e. non-inferior) than fingolimod, in terms of aRR, using a non-inferiority margin of 2. non-inferiority will be assessed based on estimated aRR-ratios (ofatumumab/fingolimod and siponimod/fingolimod) using separate one-sided [RegisteredTM] of 0.025 for each treatment. The primary endpoint will be analysed using a Bayesian negative binomial regression model adjusting for the effects of treatment, age, prior MS treatment, T2 lesion volume at baseline and number of relapses in the previous 2 years. The model will include informative priors for the log-aRRs of ofatumumab, siponimod and fingolimod, which are derived from historical studies. a key secondary objective of the study is to demonstrate that ofatumumab and/or siponimod are superior to interferon in terms of aRR. The analysis for this objective will use historical data to estimate aRR on interferon beta-1a in children. For the primary and key secondary endpoints, a hierarchical testing approach will be used to control multiplicity across the two endpoints. For ofatumumab and siponimod separately, it will first be evaluated if the primary objective of non-inferiority is reached. only if this is the case the key secondary objective will be evaluated to test for superiority versus interferons. Two weight classes for the study. above and below or equal to 40kgs. The below and equal to 40kgs have two more research visits than the higher weight group.