PDCD1 and head and neck squamous cell carcinoma: ,7 More recently, the introduction of immunotherapy has changed the management of HNSCC with the approval of anti-programmed cell death protein 1 (PD-1) immune checkpoint inhibitors (ICIs) pembrolizumab and nivolumab for the treatment of patients with recurrent or metastatic HNSCC in first line and in platinum-refractory disease.6