The cytotoxicity potential of CD8+ CAR-T cells, which varied according to hinge length, was compared using a 51Cr release assay against five cancer cell lines: MDA-MB-231 (breast cancer), U87 (glioma), M21 (melanoma), SK-ND-Z (neuroblastoma) and K562 (leukaemia). This evidence concerns the gene CD8A and breast carcinoma.