This clinical trial is focused on studying a type of skin cancer known as Cutaneous Squamous Cell Carcinoma (CSCC). The study is investigating the effects of a treatment called Cemiplimab, which is also known by its code name R2810. Cemiplimab is a medication given as an infusion, which means it is administered directly into the bloodstream through a vein. The trial will compare the outcomes of patients receiving Cemiplimab with those receiving a placebo, which is a substance with no active medication, after they have undergone surgery and radiation therapy.

The purpose of the study is to see if Cemiplimab can help prevent the return of cancer in patients who are at high risk of their cancer coming back after initial treatment. Participants in the study will be randomly assigned to receive either Cemiplimab or a placebo. The study will monitor patients over time to see how long they remain free of cancer and to track their overall health and survival. The trial will also look at the safety of Cemiplimab by observing any side effects or health changes that occur during the study.

Throughout the study, patients will have regular check-ups and tests to monitor their health and the status of their cancer. The study aims to provide valuable information on whether Cemiplimab can be an effective additional treatment for patients with high-risk CSCC, potentially improving their chances of staying cancer-free after surgery and radiation therapy.