A BCMAxCD3 bispecific T cell-engaging antibody demonstrates robust antitumor efficacy similar to that of anti-BCMA CAR T cells.

CD3-engaging bispecific antibodies (bsAbs) and chimeric antigen receptor (CAR) T cells are potent therapeutic approaches for redirecting patient T cells to recognize and kill tumors. Here we describe a fully human bsAb (REGN5458) that binds to B-cell maturation antigen (BCMA) and CD3, and compare its antitumor activities vs those of anti-BCMA CAR T cells to identify differences in efficacy and mechanism of action. In vitro, BCMAxCD3 bsAb efficiently induced polyclonal T-cell killing of primary human plasma cells and multiple myeloma (MM) cell lines expressing a range of BCMA cell surface densities.