Study to Assess Effects of Ublituximab in Pediatric Participants With Relapsing Forms of Multiple Sclerosis

The primary purpose of this study is to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of ublituximab in participants ages 10 to less than (\<)18 years and body weight greater than or equal to (≥)25 kilograms (kg) to less than or equal to (≤)40 kg with RMS (Part A) and to evaluate the non-inferiority of ublituximab compared with fingolimod in pediatric RMS participants with body weight ≥ 25 kg (Part B). The study will further evaluate long-term safety and efficacy of ublituximab in RMS in pediatric participants during its extension period (Part C).