Interestingly, in comparing a PD-1 inhibitor relative to PD-L1 inhibitors in R/M HNSCC, a decreased risk of death with PD-1 inhibitor relative to PD-L1 inhibitor has been observed, though anti-PD-L1 therapy may be associated with better outcomes in females and HPV-positive or locally recurrent disease [57]. Here, PDCD1 is linked to head and neck squamous cell carcinoma.