CD8A and neoplasm: • Together, the tumor microenvironment and TCR affected the transformation of tumor-infiltrating CD8 effector memory T cells to exhausted T cells and effector T cells.• Among CRC patients, MSI/dMMR patients showed a significantly better therapeutic response to immune checkpoint inhibitors than did MSS patients.• Intraepithelial lymphocytes and Th 17 cells were more enriched in CRC patients than in liver and lung cancer.