The Checkmate 141 trial was a landmark clinical trial that not only demonstrated the efficacy of Immune Checkpoint Inhibitor (ICI) for R/M HNSCC but also the existence of anti-tumor immunity that can be stimulated in HNSCC with the use of anti-Programmed cell Death-1 (PD-1) antibody (Nivolumab). Here, PDCD1 is linked to head and neck squamous cell carcinoma.