Impact of myeloid cells on the efficacy of anticancer chemotherapy

• Several myeloid cell populations influence the activity of anticancer chemotherapy.
• The impact of DCs and TAMs on chemotherapeutic responses depends on many factors.
• MDSCs exert immunosuppressive effects, hence limiting the efficacy of chemotherapy.
• How granulocytes and mast cells operate in this respect remains to be clarified.
• Targeting specific myeloid cell types may improve the efficacy of chemotherapy.

Tumors are not immunologically silent but evolve and respond to therapy in the context of a continuous, bi-directional interaction with the host immune system. In line with this notion, several clinically successful chemotherapeutics have been shown to mediate antineoplastic effects as they (re)activate an anticancer immune response that is generally executed by lymphoid cells. Myeloid cells play a central role in this process, not only because they critically regulate the activity of T and B lymphocytes, but also because they exert direct tumoricidal effects, at least in some settings. Here, we discuss the impact of various myeloid cell populations, including macrophages, dendritic cells and myeloid-derived suppressor cells, on the efficacy of anticancer chemotherapy.