For instance, a preclinical study examined the effect of anti-PD-1 and granulocyte-macrophage colony-stimulating factor (GM-CSF) in mouse models of colon cancer; the results showed that the combination of anti-PD-1 and GM-CSF significantly increased the antitumor response and enhanced survival [159]. This evidence concerns the gene PDCD1 and malignant colon neoplasm.