Rituximab Therapy As A First-Line Immunosuppressive Treatment In Children With Neuromyelitis Optica Spectrum Disorder: A Single-Center Experience. (P7.325)

OBJECTIVE: To report the therapeutic response to a standardized B-cell targeted immunosuppressive protocol in children with neuromyelitis optica spectrum disorders (NMOSDs). BACKGROUND: NMOSDs are inflammatory disorders of the central nervous system generally characterized by poor motor and visual outcomes. Recent observations suggest that rituximab, a monoclonal antibody targeting the CD20 antigen of B-lymphocytes, may ameliorate the course of this disorder in the pediatric population, but no standardized treatment approach has been proposed thus far. DESIGN/METHODS: We retrospectively analyzed data from nine consecutive NMOSD patients followed at The Hospital for Sick Children, Toronto, Canada. Inclusion criteria were: 1) positive anti-aquaporin 4 IgG; 2) first-line immunosuppressive treatment with rituximab (induction therapy: 500 mg/m2 infused twice 2 weeks apart; re-treatment using the same induction course at CD19+ B-cell reconstitution) in combination with an oral prednisone taper. RESULTS: Five patients (4 females; median age at onset 12.9 years, range 10.9-17.0; median follow-up 0.9 years, range 0.5-1.9) were included. The median time from onset to treatment with rituximab was 0.27 years (range 0.24-0.33). After induction therapy, two patients were relapse-free until the last follow-up, two presented one further attack before CD19+ B-lymphocyte therapeutic depletion, and one showed a relapse during B-cell elevation before re-treatment. Adverse events included urticaria (one patient) and facial rash (two patients). The median EDSS score of the patients at 6 months from onset and at last visit were 2 and 0.8, respectively. CONCLUSIONS: A standardized immunosuppressive protocol with rituximab and an oral prednisone taper appears to be a well-tolerated and effective strategy for reducing relapses in treatment-naive pediatric NMOSDs. The retrospective nature of the study, the small size of the cohort and the short follow-up limit our results. More studies are needed to assess efficacy, safety, and optimal dosage of the suggested treatment protocol.