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Background and purpose: Rituximab (RTX) is frequently used off-label in multiple sclerosis. However, studies on the risk–benefit profile of RTX in pediatric-onset multiple sclerosis are scarce.

Methods: In this multicenter retrospective cohort study, patients with pediatric-onset multiple sclerosis from Sweden, Austria and Germany, who received RTX treatment were identified by chart review. Annualized relapse rates, Expanded Disability Status Scale scores and magnetic resonance imaging parameters (new T2 lesions and contrast-enhancing lesions) were assessed before and during RTX treatment. The proportion of patients who remained free from clinical and disease activity (NEDA-3) during RTX treatment was calculated. Side effects such as infusion-related reactions, infections and laboratory abnormalities were assessed.

Results: Sixty-one patients received RTX during a median (interquartile range) follow-up period of 20.9 (35.6) months. The annualized relapse rate decreased from 0.6 (95% confidence interval [CI] 0.38–0.92) to 0.03 (95% CI 0.02–0.14). The annual rate of new T2 lesions decreased from 1.25 (95% CI 0.70–2.48) to 0.08 (95% CI 0.03–0.25) and annual rates of new contrast-enhancing lesions decreased from 0.86 (95% CI 0.30–3.96) to 0. Overall, 70% of patients displayed no evidence of disease activity (NEDA-3). Adverse events were observed in 67% of patients. Six patients discontinued treatment due to ongoing disease activity or adverse events.

Conclusion: Our study provides class IV evidence that RTX reduces clinical and radiological activity in pediatric-onset multiple sclerosis.