A recent phase Ib trial of pembrolizumab for treatment of R/M HNSCC indicated the overall response was about 18%, and the median progression-free survival (PFS) was 2 months, suggesting that this treatment may benefit HNSCC patients who previously received intensive treatment.[6] Another randomized, open-label, phase III trial of nivolumab, another monoclonal antibody that also binds to PD-1, reported the 1-year survival rate was approximately 36% in the nivolumab group but 16.6% in the control group (standard single-agent systemic therapy).[7]. Here, PDCD1 is linked to head and neck squamous cell carcinoma.