IDO1 and neoplasm: The immunomodulatory type, which is characterized by the infiltration of CD8-positive T cells into the tumor parenchyma, showed a better prognosis than the other subtypes and relatively high expression of immune checkpoint molecules, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA4), programmed death ligand 1 (PD-L1), indoleamine 2, 3-dioxygenase 1 (IDO1), and programmed cell death protein 1 (PD-1) (30).