CD19 and acute lymphoblastic leukemia: To determine the in vivo therapeutic potential of the seven CD19 CAR‐NK cells, we established the B‐ALL xenograft animal models using the luciferase‐expressing Nalm‐6 cells (Nalm‐6 luci+) in the NCG (NOD/ShiLtJGpt‐Prkdcem26Cd52Il2rgem26Cd22/Gpt strain) immune‐deficient mice.