It has been found that engineering DCs (dendritic cells) and miR-5119, when employed as a novel combined therapeutic strategy, can simultaneously suppress multiple negative regulatory molecules, including IR (inhibitory receptor) ligands, such as PD-L1 and IDO2, in DCs, thereby improving anti-tumor immune response, upregulating cytokine production, and reducing the apoptosis of T cells in breast cancer cells [29]. This evidence concerns the gene IDO2 and breast cancer.