[Specific cytotoxicity of a novel HER2-based chimeric antigen receptor modified T lymphocytes against HER2-positive tumor cells].

Objective: To construct the third generation chimeric antigen receptor based on a novel humanized anti-HER2 H1-2 scFv, and to investigate the specific cytotoxicity of H1-2 CAR modified T lymphocytes(CAR-T) against HER2(+) tumor cells. Method: The expression cassette of the third generation CAR gene and anti-HER2 H1-2 scFv were constructed and cloned into lentivirus transfer plasmid, and then the third generation H1-2 CAR was transduced into human T lymphocytes using lentivirus.Enzyme linked immunosorbent assay was used to detect the expression of cytokines IL2, and LDH release assay was used to detect the cytotoxic effect of the H1-2 CAR-T.Finally, NOD/SCID mice and HER2(+) breast cancer cell line SKBR3 were used to detect the anti-tumor effect of H1-2 CAR-T in vivo. Results: The third generation H1-2 CAR was successfully constructed.H1-2 CAR-T secreted high dose of IL2 after confrontation with HER2(+) breast cancer cells.In vitro, the cytolytic rate of H1-2 CAR-T on high expression HER2(+) tumor cells was significantly higher than that in low expression HER2 or non-expression HER2 tumor cells. At the efficacy to target ratio of 20, the cytolytic rate of H1-2 CAR-T against breast cancer cell SK-BR-3 could reach (90.1±2.8)%, while the cytolytic rate of H1-2 CAR-T against HER2(-) breast cancer cell MDA-MB-231 was only (13.5±4.7)%. In the mouse xenograft tumor model, H1-2 CAR-T cells inhibited breast cancer growth in vivo.At the end of the experiments, the average tumor weight in the H1-2 CAR-T cell treatment group was (0.7±0.1) g, the non-transfected T cell therapeutic group was (1.2±0.2) g, and the PBS group was (1.2±0.2) g. There was significant difference between the H1-2 CAR-T therapeutic group and the non-transfected T cell therapeutic group (P 0.05). Conclusion: The HER2-sepcific H1-2 CAR-T cells specifically kill HER2 positive cells, and further studies on CAR-T cells for the treatment of HER2(+) cancers are useful.