Clinical parameters associated with immunotherapy outcomes in metastatic cutaneous squamous cell carcinoma

Lay abstract: We want to understand which subgroups of patients we treat respond well to immunotherapies. The use of anti-programmed death 1 (PD1) therapy cemiplimab has shown significant clinical benefit in patients with recurrent/ metastatic cutaneous squamous cell carcinoma (R/M-cSCC), with durable responses seen in most patients. However, around 30% of patients do not benefit from the treatment, and there is a need to develop predictors of response and resistance to therapy. In this study we aimed to identify clinical parameters that predict response/resistance to therapy in a cohort of 88 R/M-cSCC patients treated with cemiplimab at three UK cancer centers. The results showed that patients with R/M-cSCC with a head and neck primary site had a significantly improved overall survival (OS) and progression-free survival (PFS) compared with other primary sites when treated with cemiplimab. The median OS and PFS were not reached for the entire cohort, and the 2-year OS rate was 60%. The overall response rate (ORR) was 60%, and 40% of patients developed immune-related toxicities of any CTCAE grade, while 13% developed grade 3 or above. The study concludes that cemiplimab treatment demonstrated significant clinical benefit with a manageable side effect profile, and future work should investigate the observed difference in survival outcomes based on primary site further.