PDCD1 and head and neck cancer: So far, More than 10 antibodies have been granted for therapy in multiple tumors 8, and over 1000 clinical trials are being implemented targeting the PD-1/PD-L1 axis 9, for example, in melanoma 10, breast cancer 11, 12, genitourinary carcinoma 13, 14, head and neck cancer 15, hepatocellular carcinoma 16, non-small cell lung cancer (NSCLC) 17, 18, etc., clearly showing the considerable value of anti-PD-1/anti-PD-L1 therapy.