Fiztasovimab (NPC-21; EV2038) is a fully human IgG1λ mAb against human cytomegalovirus (h CMV ). Fiztasovimab acts neutralizing activity by binding to the antigenic domain 1 of glycoprotein B on h CMV envelope. Fiztasovimab inhibits cell-to-cell transmission of h CMV. In Vitro Fiztasovimab is isolated from Epstein-Barr virus-transformed peripheral B cells of a healthy donor. Fiztasovimab has a broadly neutralizing activity against 4 laboratory strains (AD169, Towne, Davis, Merlin) and 42 Japanese clinical isolates, which included GCV-resistant isolates. Fiztasovimab shows anti-hMCV activities in MRC-5 human embryonic fibroblast cells and human adult retinal pigment epithelial cells with IC 50 s of 13-105 ng/mL and IC 90 s of 0.208-1.026 μg/mL. Fiztasovimab also inhibits cell-to-cell infection by hCMV isolates in adult retinal pigment epithelial cells with IC90s of 13-19 μg/mL. MCE has not independently confirmed the accuracy of these methods. They are for reference only.