Of note, Lyford-Pike et al. demonstrated that the PD-1 receptor ligand PD-L1 is differentially expressed among HPV+ and HPV- HNSCC [14], corroborating the role of the PD-1/PD-L1 pathway in HPV-related HNSCC immune resistance. The gene discussed is CD274; the disease is head and neck squamous cell carcinoma.