Definition

A T-cell engaging, human, bispecific, immunoglobulin G4 (IgG4) monoclonal antibody (T-BsAb) directed against the tumor-associated antigen (TAA) human B-cell maturation antigen (BCMA; tumor necrosis factor receptor superfamily member 17; TNFRSF17) and CD3 antigen found on T lymphocytes, with potential immunostimulating and antineoplastic activities. Upon administration, anti-BCMA/anti-CD3 T-cell engaging bispecific antibody ABBV-383 binds to both CD3 on cytotoxic T lymphocytes (CTLs) and BCMA found on BCMA-expressing tumor cells. This activates and redirects CTLs to BCMA-expressing tumor cells, which results in the CTL-mediated cell death of BCMA-expressing tumor cells. BCMA, a member of the tumor necrosis factor receptor superfamily that is specifically overexpressed on malignant plasma cells, plays a key role in promoting plasma cell survival. Binding to low-activating CD3 preferentially activates effector over regulatory T cells and stimulates minimum cytokine release.