T cells expressing a HER2-specific chimeric antigen receptor as treatment for breast cancer.

Purpose: Human endothelial growth factor receptor-2 (HER2) is a leucine kinase receptor that is closely related to cell growth and differentiation. It is very weakly expressed in a few epithelial cells in normal tissue. Abnormal expression of HER2 usually leads to sustained activation of downstream signaling pathways, enabling epithelial cell growth, proliferation, and differentiation; this disturbs normal physiological processes and causes tumor formation. Overexpression of HER2 is related to the occurrence and development of breast cancer. HER2 has become a well-established immunotherapy target for breast cancer. We chose to construct a second-generation CAR targeting HER 2 to test whether it kills breast cancer.

Methods: We constructed a second-generation CAR molecule targeting HER2, and we generated cells expressing this second-generation CAR through lentivirus infection of T lymphocytes. LDH assay and flow cytometry were perform to detect the effect of cells and animal models.

Results: The result indicated that the CARHER2 T cells could selectively kill cells with high Her2 expression. The PBMC-activated/CARHer2 cells had stronger in vivo tumor suppressive activity than PBMC-activated cells, and administration of PBMC-activated/CARHer2 cells significantly improved the survival of tumor-bearing mice, and induced the production of more Th1 cytokines in tumor-bearing NSG mice.

Conclusions: We prove that the generated T cells carrying the second-generation CARHer2 molecule could effectively guide immune effector cells to identify and kill HER2-positive tumor cells and inhibit tumors in model mice.