Dendritic cells in the tumor microenvironment: prognostic and theranostic impact

Among all immune cells, dendritic cells (DC) are the most potent APCs in the immune system and are central players of the adaptive immune response. There are phenotypically and functionally distinct DC populations derived from blood and lymphoid organ including plasmacytoid DC (pDC), conventional DC (cDC1 and cDC2) and monocyte-derived DC (moDC). The interaction between these different DCs and tumors is a dynamic process where DC-mediated cross-priming of tumor specific T cells is critical in initiating and sustaining anti-tumor immunity. Their presence within the tumor tends to induce T cell responses and to reduce cancer progression and is associated with improved patient survival. This review will focus on the distinct tumor-associated DCs (TADC) subsets in the tumor microenvironment (TME), their roles in tumor immunology and their prognostic and/or predictive impact in human cancers. The development of therapeutic immunity strategies targeting TADC is promising to enhance their immune-stimulatory capacity in cancers and improve the efficacy of current immunotherapies including immune checkpoint inhibitor (ICI) blockade and DC-based therapies.