This clinical trial is focused on studying the treatment of endometrial cancer, a type of cancer that begins in the lining of the uterus. The study involves the use of a medication called pembrolizumab, also known by its code name MK-3475, which is being compared to a placebo. Pembrolizumab is a type of medication that helps the immune system fight cancer. The trial also includes the use of adjuvant chemotherapy, which is additional cancer treatment given after the primary treatment to lower the risk of the cancer returning. The chemotherapy drugs being studied include docetaxel, carboplatin, paclitaxel, and cisplatin. These drugs are administered through intravenous infusion, which means they are given directly into a vein.

The purpose of this study is to compare the effectiveness of pembrolizumab with a placebo when used alongside chemotherapy, with or without radiotherapy, in treating newly diagnosed high-risk endometrial cancer after surgery. The study aims to determine how well these treatments work in preventing the cancer from coming back and in improving overall survival rates. Participants in the study will receive either pembrolizumab or a placebo, along with chemotherapy, over a period of time. The study will monitor the participants’ health and any changes in their condition to assess the effectiveness of the treatment.

Throughout the study, participants will undergo regular check-ups and imaging tests to track their progress. The study will also evaluate the quality of life of participants and any side effects they may experience from the treatment. The goal is to gather information that could lead to better treatment options for patients with high-risk endometrial cancer in the future.