WCN25-843 FELZARTAMAB REDUCES aPLA2R Ab BY SELECTIVELY DEPLETING CD38+ PLASMA CELLS AND PLASMABLASTS, THE MAIN PATHOGENIC CELLULAR DRIVERS OF DISEASE IN PRIMARY MEMBRANOUS NEPHROPATHY (PMN)

Felzartamab (felza) is a fully human monoclonal antibody that binds to CD38 with high affinity and depletes CD38+ antibody-producing cells such as plasma cells/plasmablasts primarily via antibody-dependent cellular cytotoxicity & phagocytosis. In studies of high-risk PMN patients, felza substantially reduced aPLA2R with associated improvements in UPCR and serum albumin. To further characterize felza with respect to efficacy biomarkers and preservation of protective immunity, we analyzed samples collected prospectively during the M-PLACE (NCT04145440) and NewPLACE (NCT04733040) trials.