Anti-B-cell therapy in patients with neuromyelitis optica spectrum disorders

Abstract

Neuromyelitis optica spectrum disorders (NMOSDs) are a group of central nervous system autoimmune diseases characterized by similar clinical manifestations, optic neuritis, and transverse myelitis being the most frequent among them. In most cases, the pathogenesis of NMOSDs is associated with autoantibodies to aquaporin-4 (AQP4-IgG). However, AQP4-IgG is not detected in at least 10-20% of patients with NMOSDs. In this subgroup and in patients with isolated transverse myelitis or optic neuritis, IgG antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) were detected. Patients seronegative for both AQP4-IgG and MOG-IgG have also been described.Objective: to evaluate rituximab (RTX) effectiveness in preventing relapses and disability in patients with NMOSDs.Patients and methods. The study included 27 patients with NMOSDs (9 men and 18 women) aged 20-51 years who received RTX in 2019-2021. The treatment protocol included intravenous infusions of 1000 mg of RTX on the 1st and 15th days, the second and subsequent courses (maintenance therapy) - intravenous infusions of 1000 mg of RTX once every six months. Treatment effectiveness was assessed by the average annualized relapse rate, the median changes of the Expanded Disability Status Scale (EDSS), and based on the magnetic resonance imaging (MRI) changes.Results and discussion. The annualized relapse rate at baseline and 18 months after the start of treatment was: all patients (n=27) — 0.6±0.3 and 0.07±0.27(p<0.0001); AQP4-IgG+ patients (n=6) — 1.1±0.9 and 0.17±0.41 (p=0.028); MOG-IgG+ patients (n=14) — 0.4±0.3 and 0.07±0.28(p=0.001); AQP4-IgG-, MOG-IgG-patients (n=7) — 0.8±0.4 and 0.0±0.0 (p=0.018). The EDSSscore at baseline and 18months after the start of treatment was: all patients — 4.5 [3.25; 6.0] and 4.0 [3.0; 5.75] (p=0.679); AQP4-IgG+ — 3.5 [2.625; 4.75] and 3.5 [2.5; 4.5] (p=0.869); MOG-IgG+ - 5.5[3.75; 6.5] and 5.5[2.75; 6.25] (p=0.465); AQP4-IgG-, MOG-IgG- - 4.0[3.75; 5.25] and 3.5[3.0; 3.5] (p=0.043). We observed two clinical relapses during the study period: one in an AQP4-IgG+ male and another one in a MOG-IgG+ woman. There was a significant decrease in the annualized relapse rate in all groups. The disability indicator did not increase during the study period, and in AQP4-IgG and MOG-IgG seronegative patients, it slightly but significantly decreased. Brain and spinal cord MRI monitoring during the treatment period revealed new active foci only in two patients with clinical relapses.Conclusion. RTX treatment in NMOSDs is reasonably efficient and safe, but with the obligatory prior patient evaluation and monitoring of treatment results.