For instance, PD-1 expression triggers metastasis through the formation of interferon-gamma (IFN-γ), tumor necrosis factor‐alpha (TNF-α), and IL-8 and targeting the JAK2/Stat3/Slug signaling pathway in pancreatic ductal adenocarcinoma (PDAC), melanoma, urinary bladder cancer (UBC), and hepatocellular carcinoma (HCC), respectively [17–20]. Here, STAT3 is linked to melanoma.