A Novel MICB-Targeting CAR-NK Cells for the Treatment of Pancreatic Cancer.

MICB-targeting CAR-NK (chimeric antigen receptor-modified natural killer cells) therapy may serve as off-the-shelf immunotherapy. We designed soluble Anti-MICB-scFv blocks tumor immune evasion targeting the MICB antigen, thereby enhancing CAR-NK cytotoxicity while reactivating endogenous immune attacks against malignancies. The Anti-MICB-CAR includes two Anti-MICB-scFv connected by an F2A linker, the CD8 hinge and transmembrane domain, the 4-1BB co-stimulatory domain, the CD3ζ activation domain, and IL-15. The expression efficiency of Anti-MICB-CAR in NK cells was investigated by flow cytometry; ELISA demonstrated that Anti-MICB-CAR-NK secreted free Anti-MICB-scFv and detected IL-15 secretion. Flow cytometry and CCK8 were utilized to study Anti-MICB-CAR-NK on tumor cell viability. The PANC-1 xenograft model was established in order to elucidate the anti-tumor effects of Anti-MICB-CAR-NK in vivo. In vitro investigations have demonstrated that the treatment of tumor cells with Anti-MICB-CAR-NK supernatant + NK cells or Anti-MICB-CAR-NK cells not only significantly increased the cytotoxic activity of tumor cells, but also secreted and produced higher levels of IL-15, IFN-γ, TNF-α, perforin, and granzyme B compared with NK cells. Anti-MICB-CAR-NK cells exhibit strong cytotoxic activity against tumor cells with high MICB expression. In vivo, Anti-MICB-CAR-NK cells exhibited a substantial inhibitory effect on tumor growth. The IHC results reveal that Anti-MICB-CAR-NK cells show a more pronounced ability to infiltrate the tumor. We demonstrated the successful expression of Anti-MICB-CAR in NK cells, which enhances the anti-tumor activity of NK cells both in vitro and in vivo. This stress ligand-targeting approach provides a promising strategy for solid tumors.