AQP4 and neuromyelitis optica: This post hoc analysis of the randomized, placebo‐controlled N‐MOmentum study (NCT02200770) of inebilizumab in neuromyelitis optica spectrum disorder (NMOSD) evaluated relationships between circulating B‐cell subsets and aquaporin‐4 immunoglobulin G (AQP4‐lgG) titers and attacks.