PDCD1 and skin squamous cell carcinoma: Cutaneous SCC (cSCC): Use of single-agent anti-PD-1 inhibition with either pembrolizumab or cemiplimab as an upfront first-line therapy for advanced or metastatic cSCC, that is not amenable to surgery or radiation, showed ORR of 42% and 52% in recurrent/metastatic disease and locally advanced disease, respectively [117,118].