Therapeutic Response in Pediatric Neuromyelitis Optica Spectrum Disorder.

BACKGROUND AND OBJECTIVE
Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune condition, which can lead to significant disability, and up to 3% to 5% of the cases have a pediatric onset. There are limited studies to guide physicians in disease-modifying treatment (DMT) choices for children with NMOSD.


METHODS
This retrospective cohort study evaluated children with NMOSD cases followed at 12 clinics in the US Network of Pediatric MS Centers. Cases were classified as Aquaporin-4 antibody positive (AQP4+) and double-seronegative (DS) when negative for AQP4+ and for myelin oligodendrocyte glycoprotein (MOG) antibody. Effect of initial DMTs including rituximab, mycophenolate, azathioprine, and intravenous immunoglobulin (IVIg) on annualized relapse rate (ARR) was assessed by negative binomial regression. Time to disability progression (EDSS increase ≥1.0 point) was modeled with a Cox proportional-hazards model.


RESULTS
91 children with NMOSD were identified: 77 AQP4+ and 14 DS (85.7% females; 43.2% Caucasian, 46.6% African American). 81 patients were started on a DMT and 10 were treatment naïve at the time of the analysis. The ARR calculated in all serogroups was 0.25 (95% CI 0.13-0.49) for rituximab, 0.33 (95% CI 0.19-0.58) for mycophenolate, 0.40 (95% CI 0.13-1.24) for azathioprine and 0.54 (95% CI 0.28-1.04) for IVIg. The ARR in the AQP4+ subgroup was 0.28 (95% CI 0.14-0.55) for rituximab, 0.39 (95% CI 0.21-0.70) for mycophenolate, 0.41 (95% CI 0.13-1.29) for azathioprine and 0.54 (95% CI 0.23-1.26) for IVIg. The ARR in the treatment naïve group was 0.97 (95% CI 0.58-1.60) in all serogroups and 0.91 (95% CI 0.53-1.56) in the AQP4+ subgroup. None of the initial DMT had a statistically significant effect on EDSS progression.


DISCUSSION
The use of DMTs, in particular rituximab, is associated with a lowered annualized relapse rate in children with NMOSD AQP4+.


CLASSIFICATION OF EVIDENCE
This study provides Class IV evidence that use of disease-modifying treatments is associated with a lowered annualized relapse rate in children with NMOSD AQP4+.