Abstract
Non-melanoma skin cancer (NMSC) includes a wide range of cutaneous tumors, the most frequent of which are basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (CSCC). Although NMSC is usually cured by surgical resection, in rare cases it can progress to locally advanced and metastatic disease. Risk factors for advanced disease include comorbidities, neglect, and immunosuppression. Advanced NMSC may require systemic treatment if surgery and radiation are not feasible. Chemotherapy, epidermal growth factor receptor (EGFR) inhibitors in CSCC, and hedgehog inhibitors in BCC have been used but are generally of limited benefit, with responses often short-lived and toxicity issues. Given the high mutational burden of NMSC, the use of immunotherapy has been investigated and two anti-PD-1 antibodies, cemiplimab and pembrolizumab, are approved for the treatment of advanced CSCC not curable by surgery or radiation. Both have shown durable responses with good tolerability in patients in phase II trials and anti-PD-1 therapy is now the standard of care for locally advanced and metastatic CSCC. PD-1 blockade is also approved as second-line therapy in advanced BCC, with frequent and durable responses after failure on hedgehog inhibitor therapy. PD-1 checkpoint inhibition is being assessed for NMSC in combination with other modalities, including oncolytic viruses and EGFR inhibitors. Adjuvant and neoadjuvant use of cemiplimab and pembrolizumab is also being investigated with several ongoing trials. Further clinical trials of immunotherapy must be prioritized in NMSC for further improvement in outcomes.