Real-World Outcomes of Ocrelizumab and Ofatumumab Treatment in Pediatric-Onset Multiple Sclerosis.

BACKGROUND AND OBJECTIVE: Ocrelizumab and ofatumumab are highly effective disease-modifying therapies (DMTs) for adult-onset multiple sclerosis and are increasingly used in pediatric-onset multiple sclerosis. However, there is a paucity of data on their safety and efficacy in pediatric-onset multiple sclerosis. We aimed to describe real-world outcomes of ocrelizumab and ofatumumab in a single center cohort of patients with pediatric-onset multiple sclerosis. METHODS: A retrospective cohort study of pediatric patients evaluated at Children's National Hospital between 2015 and 2026 who fulfilled 2017 McDonald criteria for relapsing-remitting multiple sclerosis and were treated with either ocrelizumab or ofatumumab. Patients were included regardless of whether they were treatment naïve or switching from a prior DMT. Primary outcomes were clinical relapse or radiologic worsening with new/enlarging T2 or gadolinium-enhancing lesions on magnetic resonance imaging. Secondary outcomes included safety and tolerability outcomes characterized by frequency and severity of infections, medication side effects, and hypogammaglobulinemia. Statistical analysis included descriptive statistics and an exploratory Kaplan-Meier survival analysis. RESULTS: Forty-one patients were included, with mean age at diagnosis of 15 years (range 8-17 years). There were 32/41 (78%) patients treated with ocrelizumab and 9/41 (22%) treated with ofatumumab; 22/41 (54%) received these agents as first-line DMTs. There were 19/41 (46%) patients prescribed a previous DMT, and radiologic worsening/clinical relapse was the most common reason for switching (9/19, 47%). Only 1/41 (2%) experienced a clinical relapse occurring > 3 months after ocrelizumab initiation, with an annualized relapse rate of 0.012. There were 3/41 (7%) patients who had new or enlarged T2 hyperintense lesions after re-baseline magnetic resonance imaging. There were 5/41 (12%) patients who experienced an infusion or injection-site reaction, which were all mild and managed conservatively. No patients discontinued ocrelizumab or ofatumumab because of adverse events. CONCLUSIONS: These results provide descriptive real-word data on the use of ocrelizumab and ofatumumab, especially when used as a first-line DMT in pediatric-onset multiple sclerosis. Although limited by a short follow-up period, our real-world findings provide safety and effectiveness data to inform DMT selection and shared decision making with families.