PDCD1 and metastatic neoplasm: Interestingly, the combination of anti-CSF1R and anti-PD-1 treatment further significantly inhibited metastatic tumor progression in the liver and enhanced IFN-γ+ CD8+/CD4+ and Ki67+ CD8+/CD4+ T-cell infiltration in the tumor microenvironment (Fig. 6E, F, S5I).