A randomized, international phase 3 clinical trial of participants with untreated locally incurable recurrent or metastatic HNSCC found that the ICI pembrolizumab, a neutralizing PD-1 specific antibody, is an appropriate first-line treatment for this indication (KEYNOTE-048, NCT02358031) [7]. Here, PDCD1 is linked to head and neck squamous cell carcinoma.