CD19 and B-cell chronic lymphocytic leukemia: CD19 CAR-T cells from completely responding individuals with chronic lymphocytic leukemia were enriched in memory-related genes, whereas CAR-T cells from non-responders upregulated effector- and exhaustion-related genes, suggesting that the quantity of Tcm cells is one of the major parameters for the persistence and activity of CAR-T cells [20, 21].