Some studies suggest that chemotherapy may enhance the efficacy of PD-1 inhibitors through the following mechanisms: suppression of antitumor immunity by reducing myeloid-derived suppressor cells, selectively depleting monocytes/macrophages, enhancing the recruitment of antigen-presenting cells, and promoting the phagocytosis of dendritic cells through cytokines produced by cytotoxic chemotherapy damage to cancer cells [11–13]. This evidence concerns the gene PDCD1 and cancer.