PDCD1 and neoplasm: By applying single cell RNA‐sequencing to a concurrent subcutaneous and liver tumor murine model to recapitulate liver metastases, tumor‐infiltrating exhausted CD8+ T (Tex) cells, immunosuppressive tumor‐associated macrophages, and interferon‐stimulated gene scores are identified to display opposite responses to liver metastasis and anti‐PD‐1 treatment, suggesting a complex immune regulating network.