Pembrolizumab, a humanized monoclonal antibody against PD-1 has been approved either as a monotherapy or as a combination therapy for the treatment of recurrent or metastatic melanoma [17], NSCLC, head and neck squamous cell cancer (HNSCC), gastric/gastroesophageal junction adenocarcinoma, lymphoma, urothelial cancer, cervical cancer, Merkel cell carcinoma, RCC [5], triple-negative breast cancer (TNBC) [18], cutaneous squamous cell carcinoma [19, 20], endometrial cancer [21], and HCC [22]. Here, PDCD1 is linked to head and neck squamous cell carcinoma.