A T-cell engaging bispecific antibody (T-BsAb) directed against the tumor-associated antigen (TAA) human alpha B-cell maturation antigen (aBCMA) and against the alphaCD3 (aCD3) antigen found on T-lymphocytes, with potential immunostimulating and antineoplastic activities. TNB-383B is composed of two aBCMA moieties in sequence on one arm, a single aCD3 arm, and a silenced IgG4 Fc. Upon administration of anti-aBCMA/aCD3 T-cell engaging bispecific antibody TNB-383B, this bispecific antibody 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 aCD3 preferentially activates effector over regulatory T-cells and stimulates minimal cytokine release.