A half-life extended (HLE) human bispecific T-cell engager (BiTE) antibody targeting the CD3 antigen expressed on T-lymphocytes and the cell surface protein claudin 6 (CLDN6; CLDN-6), with potential immunostimulating and antineoplastic activities. Upon intravenous administration, anti-CLDN6/CD3 BiTE antibody AMG 794 targets and binds to both CD3 expressed on T-cells and CLDN6 expressed on tumor cells. This activates and redirects cytotoxic T-lymphocytes (CTLs) to CLDN6-expressing tumor cells, produces cytokines and leads to enhanced CTL-mediated elimination of CLDN6-expressing tumor cells. CLDN6, a tight-junction protein and embryonic antigen, is expressed on a variety of tumor cells but is not expressed on normal, healthy adult cells.