As shown in Fig. 3E, the expression of PD-1 and TIM-3 on CD19-CAR T cells was evidently increased after co-cultured with Nalm6-GL (GFP/luciferase-expressing Nalm6) B-ALL cells, which indicated T-cell exhaustion, while JQ1 could reduce the inhibitory receptor upregulation induced by tumor antigen stimulation (Fig. 3F, G), and enhanced cytokine secretion and the killing function of exhausted T cells (Fig. 3H, I and Supplemental Fig. 2I). This evidence concerns the gene PDCD1 and acute lymphoblastic leukemia.