To directly measure cytotoxic capacity, we cocultured CAR T cells overnight with a target tumor cell line, MDA‐468 expressing HER2 and luciferase, at 20:1, 10:1 or 1:1 effector‐to‐target ratios and assessed percent‐specific lysis via a luminescence assay. This evidence concerns the gene ERBB2 and neoplasm.