Besides, MSI status also played a significant role in the selection of immunotherapy since MSI CRCs revealed highly upregulated expression of multiple immune checkpoints, including programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), which caused tumors infiltrated by immune cells, primarily CD8+ tumor-infiltrating lymphocytes (TILs), T helper 1 (Th1) CD4+ TILs, and macrophages. Here, CTLA4 is linked to neoplasm.