Impact of rituximab on relapse rate and disability in neuromyelitis optica

Background: Neuromyelitis optica (NMO) is a severe demyelinating disease often leading to serious disability. Accumulating evidence now implicates humoral mechanisms in its pathogenesis. In the absence of an approved therapy, anti-inflammatory/immunosuppressant drugs have been used empirically for more than three decades. Recent evidence for a role of antibody to aquaporin-4 in the pathogenesis of NMO has led to the use of rituximab, a monoclonal antibody targeting the CD20 epitope on the entire B cell lineage. Objectives: To evaluate the impact of rituximab on the relapse rate and disability in NMO. Methods: This is an IRB approved retrospective longitudinal study of NMO patients treated with rituximab. Results: We identified 53 patients with NMO, 23 of whom had been treated with rituximab. These patients (2 males, 21 females) had a mean age of 37.1 +/- 14.6 years at the time of diagnosis. Eight of the 23 treated with rituximab were treatment naive. All 23 were scheduled to receive infusions every six or 12 months after treatment initiation with a minimum follow-up of six months (median 32.5 months, range 7-63 months). Median relapse rate declined significantly from 1.87 relapses/patient per year to 0.0 relapses/patient per year. Kurtzke Expanded Disability Status Scale (EDSS) scores stabilized or improved in all patients. Use of rituximab is associated with a significant reduction in relapses and disability in patents with NMO.