We found a significant increase in these immunosuppressive markers in tumors compared to those in paratumor tissues, which is consistent with previous studies reporting the accumulation of exhausted CD8+ T cells in CRC tumors.28-30 Notably, although PD-1 and PD-L1 expression presented obvious increases in all patients, not all of the patients were responsive to PD-1 treatment. This evidence concerns the gene CD8A and colorectal carcinoma.