PDCD1 and head and neck squamous cell carcinoma: The effectiveness of these anti-PD-1/PD-L1 treatments is such that these inhibitors are now approved for use in the treatment of various types of cancer (classical Hodgkin lymphoma, metastatic melanoma, metastatic NSCLC (Non-Small Cell Lung Cancer), clear cell RCC (Renal Cell Carcinoma), HNSCC (Head and Neck Squamous Cell Carcinoma), and urothelial cancer) [3].