Experiments have shown that even when the function of CD19 CAR T cells as measured using the secretion of type I cytokines is normal, a TRAIL inhibitor can suppress the cytotoxic effect of CAR T cells when the CAR T cells are cocultured with sensitive cells, indicating that a lack of TRAIL signaling in tumor cells can lead to tumor antigen-positive resistance to CAR T-cell therapy (55). Here, CD19 is linked to neoplasm.