In order to optimize treatment efficacy and minimize toxicities from these treatments, there is an urgent need to select ideal candidates, based on individual biomarkers for anti-programmed cell death-1 (PD-1), ICIs alone or in combination, and to verify if the sequence of chemotherapy and ICIs might be conceivable in HNSCC patients. Here, PDCD1 is linked to head and neck squamous cell carcinoma.