In recent years, with the widespread use of immune checkpoint inhibitors (ICIs) in tumour therapy and the significantly prolonged survival time of patients, programmed death-1 (PD-1) inhibitors have been approved for the treatment of head and neck squamous cell carcinoma (HNSCC) patients with recurrence or metastasis after platinum-based chemotherapy1. The gene discussed is PDCD1; the disease is head and neck squamous cell carcinoma.