Notably, both radiotherapy and several cytotoxic regimens can dynamically up-regulate PD-L1 on tumor and immune cells through DNA-damage- and cGAS–STING/IFN-driven pathways, providing a biological rationale for combined chemo-/radio-immunotherapy with PD-1/PD-L1 inhibitors [85,86]. Here, PDCD1 is linked to neoplasm.