Across pivotal trials and real-world cohorts, PD-1 blockade with cemiplimab has transformed the prognosis of advanced cSCC, with objective response rates (ORRs) in the range of ~45–60%, complete responses in 10–30% of patients, and median progression-free survival (PFS) that generally exceeds 8–12 months, alongside a tail of durable responders [110,111,112,113,114]. Here, PDCD1 is linked to skin squamous cell carcinoma.