Certain immune checkpoint inhibitors (anti-PD-1 (programmed cell death protein 1), anti-PD-L1 (programmed death-ligand 1) and anti-CTLA-4 (cytotoxic T-lymphocyte-associated antigen 4) antibodies) demonstrated clinical benefit and were approved by FDA for patients with HNSCCs (head and neck squamous cell carcinoma) which showed progression after treatment with platinum-based chemotherapy. Here, PDCD1 is linked to head and neck squamous cell carcinoma.