Fianlimab and Cemiplimab vs Anti-PD1 Alone in Resectable Stage III and IV Melanoma

Study Purpose

This study is researching an experimental drug called REGN3767, also known as fianlimab (R3767), when combined with another medication called cemiplimab (each individually called a "study drug" or called "study drugs" when combined) compared with cemiplimab alone. These types of immunotherapy study drugs are collectively known as immune checkpoint inhibitors. Immunotherapies are treatments that use the immune system to recognize and kill cancer cells. The study is focused on participants with a type of skin cancer known as melanoma. The objective of this study is to see if the combination of fianlimab and cemiplimab is an effective treatment compared to cemiplimab in participants with high-risk, resectable melanoma. Participants will receive treatment before surgery, undergo resection, and then will have the option to continue treatment after resection. The study is looking at several other research questions, including: - What side effects may happen from receiving the study drug(s). - How much study drug(s) is in the blood at different times. - Whether the body makes antibodies against the study drug(s) (which could make the drug less effective or could lead to side effects). Antibodies are proteins that are naturally found in the blood stream that fight infections. - How administering the study drugs might improve quality of life.