B cell and aquaporin‐4 antibody relationships with neuromyelitis optica spectrum disorder activity

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. Among participants receiving placebo, CD20 + and CD27 + B‐cell counts were modestly increased from the pre‐attack visit to attack; plasmablast/plasma cell gene signature was increased from baseline to the pre‐attack visit ( p = 0.016) and from baseline to attack ( p = 0.009). With inebilizumab treatment, B‐cell subset counts decreased and did not increase with attacks. No difference in change of AQP4‐IgG titers from baseline to time of attack was observed.