CRISPR Knock-in of a Chimeric Antigen Receptor into GAPDH 3'UTR Locus Generates Potent B7H3-specific NK-92MI Cells

CAR-NK therapy is becoming a promising approach to treat solid tumors. However, the random insertion of the CAR gene and inflexible CAR expression caused by common preparation methods significantly impact its efficacy and safety. Here we successfully established a novel type of CAR-NK cells by integrating CAR sequences into the GAPDH 3'UTR locus of NK-92MI cells (CRISPR-CAR-NK), achieving site-specific integration of the CAR gene and allowing endogenous regulatory components to govern CAR expression. CRISPR-CAR-NK cells had comparable growth capacity but displayed superior anti-tumor activity compared with their lentiviral counterparts. They activated and degranulated more effectively when co-cultured with tumor cells, due to increased expression of activating receptors and decreased expression of inhibitory molecules. They also enhanced the production of Granzyme B and IFN-γ, and more effectively triggered the IFN-γ pathway. Moreover, CRISPR-CAR-NK cells demonstrated distinct properties from conventional CAR-NK concerning metabolic features and signal dependence. Notably, CRISPR-CAR-NK cells exhibited lower metabolic levels without compromising antitumor activity, and their function was less reliant on the PI3K-AKT pathway, implying that the CRISPR-CAR-NK cells have significant potential for enhanced synergy with AKT inhibitors and adaptation to nutrient stress within the tumor microenvironment. These findings provide a novel potential strategy for cancer immunotherapy and an experimental foundation and paradigm for optimizing CAR-NK cells utilizing CRISPR technology, highlighting the potential of CRISPR to advance immunotherapies.