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Study of Pembrolizumab with Chemotherapy for High-Risk Endometrial Cancer Patients After Surgery

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What is this trial about?

A plain-language summary of the goals, design and what participants do

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.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, you will be randomly assigned to receive either the medication pembrolizumab or a placebo. A placebo is a substance with no active medication, used to compare the effects of the actual drug.

    You will also receive adjuvant chemotherapy, which is additional cancer treatment given after the primary treatment to lower the risk of the cancer returning. This may include drugs like carboplatin, paclitaxel, or cisplatin.

  2. Step 2

    Treatment administration

    The medications, including pembrolizumab or placebo, and chemotherapy drugs, will be given through an intravenous infusion. This means the medication will be delivered directly into your bloodstream through a vein.

    The specific dosage and frequency of the medications will be determined by the study protocol and your healthcare team.

  3. Step 3

    Monitoring and follow-up

    Throughout the study, your health will be closely monitored. This includes regular check-ups and imaging tests to assess your response to the treatment.

    You will be evaluated for disease-free survival, which means the length of time after treatment during which no signs of cancer are found, and overall survival, which refers to the length of time from the start of treatment that patients are still alive.

  4. Step 4

    Completion of the study

    The study is expected to continue until March 2026. Your participation may last until the study ends or until you and your healthcare team decide it is best to stop.

    After completing the study, you may have follow-up visits to monitor your health and discuss any further treatment options if necessary.

Who can join the trial?

9 criteria

  • The participant must be female.
  • The participant must have a new diagnosis of Endometrial Carcinoma or Carcinosarcoma (also known as Mixed Mullerian Tumor) confirmed by a tissue examination.
  • The participant must have had surgery aimed at curing the cancer, which included removal of the uterus (hysterectomy) and both ovaries and fallopian tubes (bilateral salpingo-oophorectomy).
  • The participant must be at high risk for cancer coming back after surgery. This includes specific stages and types of cancer as defined by medical guidelines.
  • The participant must be disease-free with no signs of cancer in the local area or spread to other parts of the body after surgery and on imaging tests.
  • The participant must not have received any radiation or drug treatments, including immunotherapy, hormonal therapy, or a specific type of chemotherapy called hyperthermic intraperitoneal chemotherapy (HIPEC), for endometrial cancer.
  • The participant must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, which means they are fully active or have some symptoms but do not need bed rest, within 7 days before being assigned to a treatment group.
  • The participant must provide a sample of their tumor tissue from the current diagnosis for testing to determine the type of cancer and a specific genetic feature called mismatch repair (MMR) status.
  • The participant must have adequate organ function within 7 days before being assigned to a treatment group, meaning their organs are working well enough to participate in the study.

Who cannot join the trial?

10 criteria

  • Patients with a history of other types of cancer, except for endometrial cancer, cannot participate.
  • Patients who have had a severe allergic reaction to pembrolizumab or any of its ingredients are excluded. Pembrolizumab is a type of medication used in cancer treatment.
  • Patients with active infections that require treatment with antibiotics, antivirals, or antifungals are not eligible.
  • Patients with autoimmune diseases, which are conditions where the immune system attacks the body, are excluded.
  • Patients who are pregnant or breastfeeding cannot participate.
  • Patients with a history of organ transplant are not eligible.
  • Patients with uncontrolled high blood pressure or heart disease are excluded.
  • Patients who have received another investigational drug within the last 4 weeks are not eligible.
  • Patients with a history of drug or alcohol abuse that could interfere with the study are excluded.
  • Patients with any other medical condition that the study doctors believe would make participation unsafe are not eligible.
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Investigated drugs

Pembrolizumab is a type of medication known as an immunotherapy. It works by helping your immune system fight cancer cells. In this trial, pembrolizumab is being tested to see if it can help prevent the return of endometrial cancer after surgery. It is used in combination with chemotherapy and possibly radiotherapy to see if it can improve the chances of staying cancer-free and living longer.

What is already known about the treatment

Pembrolizumab – Pembrolizumab is administered as an intravenous infusion, meaning it is given directly into the bloodstream through a vein. It is currently being studied in clinical trials for its effectiveness in treating high-risk endometrial cancer, a type of cancer that affects the lining of the uterus. The main therapeutic use of pembrolizumab in this trial is to improve disease-free survival and overall survival in patients after surgery. At the molecular level, pembrolizumab works by blocking a specific protein on immune cells, which helps the immune system recognize and attack cancer cells more effectively. It is classified as an immune checkpoint inhibitor, a type of drug that helps the body's immune system fight cancer.

Investigated diseases

Endometrial cancer – Endometrial cancer is a type of cancer that begins in the lining of the uterus, known as the endometrium. It typically starts when cells in the endometrium undergo changes and begin to grow uncontrollably. As the disease progresses, these cancerous cells can invade nearby tissues and organs. In some cases, the cancer may spread to other parts of the body through the lymphatic system or bloodstream. The progression of endometrial cancer can vary, with some cases remaining localized while others become more advanced. The disease is often detected due to symptoms such as abnormal vaginal bleeding, especially after menopause.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2022-501973-37-00Protocol codeMK-3475-B21Estimated enrolment1 095 patientsSponsorMerck Sharp & Dohme LLC

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