Notably, all seven types of CD19 CAR‐NK cells significantly reduced the tumour burden for a prolonged 21‐day period post‐treatment in the treated tumour‐bearing mice (On Day 14, Tumour only vs. Mock‐NK, p < 0.01, Mock‐NK vs. seven CAR‐NK, p < 0.05. This evidence concerns the gene CD19 and neoplasm.