PDCD1 and cancer: The safety and efficacy of α-PD-1/PD-L1 combined with IL-2 pathway agonist (NKTR-214/BEMPEG) [321], PEGylated IL-10 (Pegilodecakin) [322], IL-12 plasmid (Tavo) [323], IL-15 agonist (ALT-803) [324], or PEGylated IFN-α [325] had been validated in cancer patients.