PD-1 has been proven to contribute to the longer median OS in comparison with traditional chemotherapy in HNSCC by the following three randomized phase III trials: 8.4 months vs. 6.9 months in KEYNOTE-040; 11.6 months vs. 10.7 months in KEYNOTE-048, and 7.5 months vs. 5.1 months in CHECKMATE-141 [44,45,46]. The gene discussed is PDCD1; the disease is head and neck squamous cell carcinoma.