[Modification with IL-21 and CCL19 enhances killing efficiency and tumor infiltration of NKP30 CAR-T cells in lung cancer].

Objective: To investigate whether modification with IL-21 and CCL19 enhances killing and tumor-infiltrating efficiency of NKP30 CAR-T cells in lung cancer.

Methods: The modified IL-21-CCL19 NKP30 CAR-T cells expressing IL-21 and CCL19 fusion gene was constructed based on NKP30 CAR-T cells and stimulated with CD3CD28 antibodies and IL-2. The immunophenotype and migration of the cells in the presence of IL-21 were investigated using flow cytometry and migration experiments. Lactate dehydrogenase (LDH) release and sphere formation assays were used to assess the killing and infiltration capabilities of CAR-T cells, and the secretion levels of IFN-γ, IL-21 and CCL19 were determined with enzyme-linked immunospot assay (ELISPOT) and ELISA. A zebrafish model bearing HCG-27 cell xenograft was established by microinjection of the tumor cells into the yolk sac followed 24 h later by injection of the immune cells at the same site, and the fluorescence signals were captured using a fluorescent microscopy.

Results: The NKP30 ligand B7H6, which was almost undetectable in normal tissues and blood cells, was highly expressed (over 90%) in lung cancer cells. Compared with NKP30 CAR-T cells and conventional T cells, IL-21-CCL19 NKP30 CAR-T cells exhibited stronger proliferative and migration capabilities with the formation of central memory T cells. The reduced expressions of CTLA4 and PD1 in the constructed cells resulted in enhanced killing efficiency against lung cancer cells accompanied by significantly increased production of IFN-γ, IL-21 and CCL19. In the zebrafish models, CAR-T cells exhibited stronger cytotoxicity and proliferative abilities than typical T cells, but these differences were not statistically significant between the two CAR-T cells.

Conclusion: Modification of NKP30 CAR-T cells with IL-21 and CCL19 facilitates their access into solid tumors for more effective tumor cell killing while producing a large number of memory T cells.