Study of Pembrolizumab (MK-3475) in Combination With Adjuvant Chemotherapy With or Without Radiotherapy in Participants With Newly Diagnosed Endometrial Cancer After Surgery With Curative Intent (MK-3475-B21 / KEYNOTE-B21 / ENGOT-en11 / GOG-3053)

To join this study, you must have a new diagnosis of womb cancer or a similar type called carcinosarcoma, and you must have already had surgery to remove it, including your womb and both ovaries. Your doctors must consider your cancer to be at a higher risk of returning after surgery. This includes certain stages of the cancer or if specific changes (like in the p53 gene) are found in your tumour. Importantly, after your surgery and scans, there should be no signs of cancer left in your body, either locally or spread to distant areas.

You cannot have already received any cancer treatment like radiation, chemotherapy, immunotherapy, or hormonal therapy for this womb cancer diagnosis. You also need to be generally well enough to take part, as assessed by a doctor, and have healthy organ function. The hospital will need a sample of your tumour tissue to check special markers, which is a standard part of assessing eligibility.

There are also some reasons why you wouldn't be able to join. For example, if your womb cancer has already come back, or if you have certain other types of womb tumours like sarcomas. If your cancer is a specific early stage (FIGO Stage I/II) of endometrioid type without the specific p53 changes, you would also not be eligible. Also, if you have a known particular gene change called a POLE mutation, or if your cancer was a very advanced stage (FIGO Stage IVB), even if it seems to have been removed, you would not be able to participate.

If you decide to join this study, you would first go through a screening process to check if you meet all the requirements. If you do, you would then be randomly assigned to one of two groups: either the group receiving pembrolizumab plus standard chemotherapy (with or without radiotherapy) or the group receiving a placebo (a dummy drug) plus standard chemotherapy (with or without radiotherapy). Neither you nor your doctor would choose which group you are in, and you often wouldn't know which treatment you are receiving.

Taking part would involve regular hospital visits for your treatment, which would include infusions (drips) of the study drug or placebo, and checks by the study team. You would also have standard chemotherapy and potentially radiotherapy, as determined by your doctors. Throughout the study, you'd have appointments for physical exams, blood tests, and scans to monitor your health and how the treatment is working. This monitoring would continue for a period after your main treatment ends, typically for several years, to track your long-term health and if the cancer returns. The total duration of your participation, including follow-up, could be several years.