IDO1 and non-small cell lung carcinoma: IDO-1 expression by the cancer cell was associated with immunosuppressive function through inhibition of T-cell receptor expression and induction of Treg [for review see (83)] andhigh IDO-1 activity was linked with ICB refractoriness in NSCLC (84), therefore making it a very attractive target and multiple inhibitors have been developed and are under evaluation in multiple cancer types.