Ofatumumab Treatment Used in Pediatric MOGAD: A Retrospective Case Series.

Background: Myelin oligodendrocyte glycoprotein antibody-associated disorder (MOGAD) is a rare central nervous system demyelinating disease with a variable course, including both monophasic and relapsing phenotypes. Effective treatment options, particularly for relapsing disease, remain limited. Ofatumumab (OFA), a subcutaneous anti-CD20 monoclonal antibody approved for multiple sclerosis, has not been studied in pediatric MOGAD. This study aims to assess its safety and efficacy in this population. Objective: To describe the safety and efficacy of off-label OFA use in pediatric MOGAD patients. Patients and Methods: We conducted a retrospective case series of consecutive pediatric patients with relapsing MOGAD who received OFA. Clinical data, including relapse history, annualized relapse rate (ARR), laboratory findings, and adverse events, were collected and analyzed. Results: Three pediatric (1 female, 2 males) were included. Age at onset was 2.3, 6.1, and 2.5 years; disease duration before OFA was 6.3, 2.2, and 9.1 years; and age at OFA initiation was 8.6, 8.3, and 11.6 years. Two patients started OFA due to breakthrough relapses on mycophenolate mofetil (MMF); one switched from maintenance intravenous immunoglobulin (IVIG) for administrative convenience. Treatment durations were 12, 9, and 9 months. All patients achieved rapid B-cell depletion (CD19+ < 10 cells/μL), which was sustained in two. Serum MOG-IgG titers increased in two patients and became negative in one. Two patients remained relapse-free during OFA treatment; one experienced a single relapse at 3 months. ARR decreased in all three patients post-OFA initiation. OFA was well tolerated. Only one patient developed transient fever after the first injection, which resolved with symptomatic treatment and did not recur. Conclusion: In this small case series, OFA was generally well-tolerated and associated with a reduction in ARR, suggesting a potential role in combination therapy for relapsing pediatric MOGAD. Given the use of combination treatments in some cases, including OFA+MMF and IVIG, the role of OFA alone remains unclear. Its subcutaneous route provides practical advantages in terms of convenience. Owing to the small sample size and relapse observed in one patient, these findings remain preliminary and warrant validation in larger, prospective studies.