Lastly, combining PD-L1 CAR-NK cells with immune checkpoint inhibitors may further enhance anti-tumor activity, as reported in CAR-T studies involving engineered CARs to secrete anti-PD-1 scFvs [70], co-transduction with PD-1 short hairpin ribonucleic acid (RNA) [71], or adenine base editing to downregulate PD-1 expression [72]. Here, PDCD1 is linked to neoplasm.