Notably, in certain TMEs, IFN-I exhibit opposing effects to induce the expression of cell death ligand 1 (PD-L1), enzyme IDO (indoleamine 2,3-dioxygenase), interleukin-10 (IL-10), regulatory T cells (Tregs) and other anti-inflammatory mediators [100], to evade the tumor-induced immune suppressive TME [101,102]. Here, IDO1 is linked to neoplasm.