PDCD1 and neoplasm: Second, TRMBE and 5-FU combined therapy regulated the blood cytokines (IL-6, IL-10, TGF-β, IFN-γ), immune cells in spleen (PMN-MDSCs), and modulated the tumor microenvironment, most notably the percentage of infiltrating PMN-MDSCs, NK cells, and PD-1+ CD8+ T cells.