The US Food and Drug Administration (FDA) has approved immune checkpoint inhibitors (ICIs), and specifically, programmed cell death protein 1 (PD-1) inhibitor pembrolizumab for recurrent and metastatic HNSCC based on the KEYNOTE-048 trial for which 882 participants were recruited (3, 4). This evidence concerns the gene PDCD1 and head and neck squamous cell carcinoma.