Abstract

Significance Recent clinical trials have shown highly promising responses in a subset of patients treated with immune checkpoint inhibitory anti–programmed cell death-1, anti–programmed cell death ligand-1, and anti–cytotoxic T-lymphocyte-associated antigen-4 antibodies, but the majority of patients in these trials remained unresponsive. Our results show that elevated myeloid-derived suppressor cells(MDSCs) are responsible for the resistance and that elimination of MDSCs can lead to cures of experimental, metastatic tumors.