The results showed that the killing efficiency of CAR T on tumour cells was significantly higher than that of the T cells after co‐incubation at potent target ratios of 10:1, 5:1 and 2.5:1 (Figure 1A), indicating that CD19 CAR T cells killed CD19 antigen‐positive tumour cells in a dose‐dependent manner. Here, CD19 is linked to neoplasm.