PDCD1 and cancer: The authors also mention the need to elucidate the mechanisms of the antitumor response produced by irradiation in combination with ICI, but identify CXCL16, CTLA-4, CD47, humanized epidermal growth factor receptor (HER), PD-1, and PD-L1 as key players in the “immune escape” of tumor cells; the results showed an unfavorable response of malignant tumors to irradiation [13].