IDO2 and neoplasm: To understand the mechanism of immune modulation by the TBME, we compared the expression of regulatory genes mediating: (1) T-cell activation or inhibition, which plays a critical role in adaptive immune response to the tumor; (2) antigen presentation, which regulates T-cell-mediated immune response; (3) metabolism, including IDO1, IDO2 and TDO that play an important role in tumor-immune escape16, and (4) phagocytosis, which may eliminate the tumor cells in an antibody-dependent manner9.