Pittock SJ, et al. - In this randomized, double-blind trial, researchers determined the impact of eculizumab (a terminal complement inhibitor) on the frequency of relapse in patients with aquaporin-4 antibodies (AQP4-IgG)–positive disease neuromyelitis optica spectrum disorder (NMOSD). One hundred forty-three adults were randomly assigned in a 2:1 ratio to receive either intravenous eculizumab (900 mg weekly for the first four doses beginning on day 1, followed by 1,200 mg every 2 weeks starting on week 4) or matched placebo. Investigators found that those who received eculizumab had a significantly lower risk of relapse among patients with AQP4-IgG–positive NMOSD vs those who received placebo. In the eculizumab group, upper respiratory tract infections and headaches were more common. There was no significant difference in the progression of disability measures between groups.