Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune condition which can led to significant disability. Approximately 4% of the NMOSD cases are pediatric onset. At present, there are limited studies that aim at guiding physicians in their treatment choices for NMOSD in children.
To evaluate the effect of different disease modifying therapies (DMT) with respect to attack prevention in children with NMOSD.
Cohort study that included 12 clinical centers participating in the US Network of Pediatric MS Centers. Cases were validated for NMOSD diagnostic criteria and classified via serostatus as AQP4+, MOG+, or double-seronegative (DS). Clinical data, including demographics, attack details, type of initial DMT (rituximab, mycophenolate mofetil, azathioprine, IVIg) and neurological visit data were extracted from charts, centrally collected in a database, and analyzed. Treatment response in the three serostatus subgroups was evaluated. Effect of DMTs on annualized relapse rate (ARR) was assessed by negative binomial regression.
111 pediatric patients with NMOSD were identified: 80 AQP4+, 10 MOG+, 14 double seronegative (DS), and 7 with unknown serostatus (94 females and 17 males; 48 white, 47 African American, 13 other races). Mean follow-up duration was 1.9 years (SD±2.2). About 6% of patients were treatment-naive. First-line DMTs varied by serostatus: in the AQP4+ subgroup 42% used rituximab, 16% mycophenolate mofetil, 16% azathioprine, and 8% IVIg. Among MOG+ patients, 13% received rituximab, 13% azathioprine, 13% mycophenolate, and 38% IVIg. Within the DS group, rituximab was used in 21% of cases, azathioprine in 7%, mycophenolate in 21%, and IVIg in 21%. In the unknown serogroup, 33% received rituximab, 17% azathioprine, 0% mycophenolate, and 33% IVIg. The ARR calculated in all the serogroups was 0.25 (95% CI 0.13-0.46) for rituximab, 0.73 (95% CI 0.27-2.00) for azathioprine, 0.40 (95% CI 0.18-0.89) for mycophenolate, and 0.56 (95% CI 0.26-1.20) for IVIg. In the AQP4+ subgroup, the patients started on rituximab showed an ARR of 0.25 (95% CI 0.13-0.48), those on azathioprine an ARR of 0.76 (95% CI 0.24-2.39), those on mycophenolate an ARR 0.43 (95% CI 0.17-1.07), and those on IVIg an ARR of 0.63 (95% CI 0.26-1.55).
This retrospective study showed that rituximab is associated with a lowered annual relapse rate in pediatric NMOSD and in particular in the AQP4+ subgroup.