Ofatumumab in pediatric multiple sclerosis: a case series.

Pediatric-onset multiple sclerosis (POMS), accounting for ~5% of all MS cases, is a chronic immune-mediated demyelinating disorder of the central nervous system. Relapse prevention remains a challenge, and B cells play a central role in the pathogenesis. Ofatumumab (OFA), a fully human anti-CD20 monoclonal antibody, is approved for adult MS. To assess the safety and efficacy of off-label OFA use in pediatric MS patients. We retrospectively analyzed clinical data from four pediatric patients with MS who received OFA. Retrospective case series. Four pediatric MS patients received OFA as disease-modifying treatment at ages ranging from 9.7 to 12.8 years for durations between 6 and 20 months. Three patients received OFA treatment for uncontrolled relapses, while one switched from rituximab. After the initial treatment phase of OFA, B-cell depletion was achieved in three patients, and this depletion was not consistently maintained throughout the maintenance phase. All patients remained relapse-free, with no new or enlarging T2 lesions or contrast-enhancing lesions observed on MRI or EDSS progression. The annual relapse rate after OFA treatment decreased compared with that before OFA treatment. One patient reported mild adverse events, including transient fever and atopic dermatitis, all of which were manageable. Ofatumumab showed favorable tolerability and potential benefit in this small pediatric MS cohort. Its subcutaneous administration offers practical advantages. While these findings suggest feasibility, the limited evidence precludes clinical recommendation at this stage. Larger prospective studies are warranted.