Various studies have suggested that the markers of T‐cell exhaustion, such as CTLA‐4, BTLA, LAG‐3, 2B4, TIM‐3, CD160, and PD‐1, induce the functionally impaired state and thereby suppress the proliferation of the exhausted T cells in tumor tissues.20, 21. This evidence concerns the gene CTLA4 and neoplasm.