PDCD1 and neoplasm: The combination of PD-1 inhibition with pegylated-IFNα had a synergistic effect, increased the efficacy of PD-1 Ab and restored CD8+ T cell cytotoxicity. i.e., improved T-cell infiltration and significantly extended mouse survival compared to control or single agent (p<0.01). Pegylated-IFNα induces tumour cells to secrete the chemokine CCL4 and recruits cytotoxic CD8+ T cells to infiltrate the TME, consequently overcoming immune responses by increasing PD-1 expression in CD8+ T cells via the IFNAR1-JAK1-STAT3 signalling pathway.