TDO2 and neoplasm: Interestingly, the treatments also resulted in increased expression of some immunosuppressive genes, such as Ido1, Mpo, Nos2 and Tdo2, which may reflect a counter-regulatory mechanism induced by the tumor and/or myeloid cells in response to enhanced IFNγ production by anti-PD-L1 or combination treated tumor-infiltrating T cells.