Evaluation of Clinical Parameters Associated with Response and Resistance to Cemiplimab in Locally Advanced and Metastatic Cutaneous Squamous Cell Carcinoma: A Multi-Institutional Retrospective Cohort Study.

Cutaneous squamous cell carcinoma (cSCC) is a common cancer with increasing incidence and 5% of patients develop incurable disease, often resistant to chemotherapy. The anti-PD-1 therapy cemiplimab has shown high efficacy in clinical trials. This retrospective study evaluated the real-world effectiveness of cemiplimab in incurable cSCC and examined factors influencing response and toxicity. Data from 86 patients across three UK healthcare providers were analysed. Median progression-free survival (PFS) and overall survival (OS) were not reached, with 38% showing durable responses beyond 12 months. The overall response rate was 60.8% (95% CI 49-71), and the clinical benefit rate was 74.3% (95% CI 63-83). A head and neck primary site was associated with improved PFS (p = 0.008) and OS (p = 0.023), while concurrent immunosuppression was associated with worse PFS (p < 0.001). These findings align with clinical trials, suggesting cemiplimab is effective and safe in the recurrent/metastatic setting.