To assess the strict dependence of the HER2-CD3-Fc bsAb-induced T cell cytotoxicity on the HER2 antigen and exclude the possibility of a non-specific antitumor effect of the bsAb, we generated isogeneic her2 knockout cells using the CRISPR/Cas9 system for both the NSCLC cell line A549 and the ovarian cancer cell line A1847. The gene discussed is ERBB2; the disease is ovarian carcinoma.