11.30 Comparison of fixed high dose with variable low dose rituximab in neuromyelitis optica spectrum disorders

Abstract

IntroductionRituximab is an effective treatment for neuromyelitis optica spectrum disorders (NMOSD) but the ideal dosing regimen is unknown. This study compares a standard fixed dosing regimen (2 g 6-monthly) with a lower variable dosing regimen (2 g induction, then 1–2 g on repopulation of CD19+ B-cells to ≥1% of circulating lymphocytes, tested monthly).MethodRetrospective review of all rituximab-treated adult NMOSD patients who had at least 6months relapse-free follow-up from treatment initiation (n=52). Rituximab dosing fell into four groups: Purely fixed dosing (n=13), purely variable dosing (n=18), fixed then variable dosing (n=18), other (n=3).ResultsMedian annualized relapse rate (ARR) was not significantly different between these groups. Pooled analysis of all fixed dosing (n=31, median duration 25 months) versus all variable dosing (n=36, median duration 38 months) showed median and mean ARRs of 0.00 and 0.10 in both groups. Patients on fixed dosing received a median 3.9 infusions/year; those on variable doing received only 1.5 infusions/year.ConclusionVariable dosing of rituximab with B-cell monitoring appears as effective as fixed dosing with lower cumulative drug doses. This approach led to reduced costs, increased patient convenience and has the potential for reducing side effects.