To describe the efficacy and safety of eculizumab in patients in the PREVENT trial (NCT01892345) who had previously received rituximab.

In PREVENT, eculizumab was associated with a significant reduction in relapse risk versus placebo and was well tolerated. In total, 46 patients (26/96 in eculizumab arm, 20/47 in placebo arm) were previously treated with the monoclonal antibody rituximab.

Adults with aquaporin-4 immunoglobulin G-positive neuromyelitis optica spectrum disorder received eculizumab (maintenance dose, 1200 mg/2 weeks) or placebo with/without concomitant immunosuppressive treatment (except rituximab/mitoxantrone). A post hoc descriptive analysis was performed using data from patients with any prior rituximab treatment (within the previous year only for review of adverse events [AEs]) recorded more than 3 months before randomization.

Baseline characteristics of the prior rituximab subgroup were similar to the total PREVENT population; however, the subgroup included a lower proportion of Asian patients (10.9% vs 36.4% in total PREVENT) and greater representation from the Americas (58.7% vs 30.8%). In the subgroup, median times from last dose of rituximab to meningococcal vaccination and to first dose of study treatment were 31.7 and 38.7 weeks, respectively. Adjudicated relapses occurred in 1/26 (3.8%) and 7/20 (35.0%) patients in the eculizumab and placebo arms (hazard ratio, 0.093; 95% confidence interval, 0.011–0.755; p = 0.0055), respectively. Rates of AEs for eculizumab and placebo were 1025.8 and 1029.1 events/100 patient-years (100% of patients), and rates of serious AEs were 46.9 and 66.0 events/100 patient-years (38.9% and 47.1% of patients), respectively. Serious infections/infestations were recorded in 2/18 (11.1%) and 2/17 (11.8%) patients in the eculizumab and placebo arms, respectively.