A bispecific T-cell engager (BiTE) antibody composed of two single-chain variable fragments (scFv), one directed against the tumor-associated antigen (TAA) delta-like protein 3 (DLL3) fused to one that is directed against the CD3 antigen found on T-lymphocytes, with potential immunostimulating and antineoplastic activities. Upon administration, tarlatamab binds to both the CD3 antigen on cytotoxic T-lymphocytes (CTLs) and the DLL3 antigen found on DLL3-expressing tumor cells. This activates and redirects CTLs to DLL3-expressing tumor cells, which results in the CTL-mediated cell death of DLL3-expressing tumor cells. DLL3, a Notch pathway protein, is overexpressed on a variety of cancer cell types. It plays a key role in embryonic development and in tumor initiation and proliferation.