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Study of Pembrolizumab with Chemotherapy for Patients with Gastric or Gastroesophageal Junction Cancer

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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 treatments for gastric cancer and gastroesophageal junction (GEJ) adenocarcinoma, which are types of cancer that affect the stomach and the area where the stomach meets the esophagus. The study is testing a combination of treatments to see how effective they are in improving outcomes for patients with these cancers. The main treatment being tested is pembrolizumab, also known by its code name MK-3475, which is a type of medication that helps the immune system fight cancer. Pembrolizumab is being combined with different chemotherapy drugs, including cisplatin, capecitabine, 5-fluorouracil, docetaxel, oxaliplatin, and calcium folinate (also known as leucovorin calcium). A placebo, which looks like the real treatment but does not contain the active drug, is also used for comparison.

The purpose of the study is to evaluate how well these treatments work in preventing the cancer from coming back or spreading, and to assess the overall survival of patients. The study will also look at the safety and side effects of the treatments. Participants will receive the treatments before and after surgery to remove the cancer. The study will follow participants over a period of time to monitor their health and the effectiveness of the treatments.

Throughout the study, participants will receive the treatments through intravenous infusion, which means the medication is given directly into a vein, or orally, which means taking the medication by mouth. The study aims to provide valuable information on the best treatment options for patients with gastric and GEJ adenocarcinoma, helping to improve future care and outcomes for individuals with these types of cancer.

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

    Initial treatment phase

    The trial begins with the administration of chemotherapy combined with either pembrolizumab or a placebo. The chemotherapy regimen includes cisplatin and capecitabine (XP) or cisplatin and fluorouracil (FP).

    Pembrolizumab is given as an intravenous infusion. Capecitabine is taken orally, while cisplatin and fluorouracil are administered through intravenous infusion.

    This phase aims to reduce the size of the tumor before surgery.

  2. Step 2

    Surgical intervention

    Following the initial treatment phase, surgery is performed to remove the tumor. The timing of the surgery is based on the response to the pre-operative chemotherapy.

  3. Step 3

    Post-surgery treatment phase

    After surgery, additional chemotherapy is administered. This may again include the combination of pembrolizumab or placebo with chemotherapy (XP or FP).

    The goal of this phase is to eliminate any remaining cancer cells and reduce the risk of recurrence.

  4. Step 4

    Monitoring and follow-up

    Throughout the trial, regular monitoring is conducted to assess the response to treatment and any side effects.

    Follow-up visits are scheduled to evaluate overall health and the effectiveness of the treatment.

Who can join the trial?

8 criteria

  • The patient must have a type of cancer called **gastric or gastroesophageal junction (GEJ) adenocarcinoma** that has not been treated before. This means the cancer is located in the stomach or where the stomach meets the esophagus.
  • The patient should be planning to have surgery after receiving chemotherapy, which is a treatment using drugs to kill cancer cells.
  • The patient must agree to provide a sample of the tumor tissue before starting the study and at the time of surgery.
  • The patient should have an **ECOG performance status** of 0 to 1. This is a scale used to assess how well a patient can perform daily activities, with 0 being fully active and 1 being restricted in physically strenuous activity but able to carry out light work.
  • The patient must have **adequate organ function**, meaning their organs are working well enough to handle the treatment.
  • Male patients who can have children must agree to use a reliable form of birth control during the study and for 180 days after the last dose of chemotherapy.
  • Female patients who can have children must agree to use a reliable form of birth control during the study and for 180 days after the last dose of chemotherapy or 120 days after the last dose of pembrolizumab, whichever is longer. Pembrolizumab is a medication used to help the immune system fight cancer.
  • The patient must have a life expectancy of more than 6 months, meaning they are expected to live longer than 6 months.
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Investigated drugs

  • Pembrolizumab (MK-3475)

    is an immunotherapy medication used in this trial. It works by helping the immune system recognize and attack cancer cells. In this study, it is combined with chemotherapy to treat patients with gastric and gastroesophageal junction adenocarcinoma.

  • Cisplatin

    is a chemotherapy drug used in this trial. It works by damaging the DNA of cancer cells, which prevents them from dividing and growing. It is used in combination with other chemotherapy drugs to enhance its effectiveness.

  • Capecitabine

    is another chemotherapy medication included in the trial. It is taken orally and is converted into 5-fluorouracil in the body, which helps to stop the growth of cancer cells.

  • 5-Fluorouracil (5-FU)

    is a chemotherapy drug that interferes with the growth of cancer cells. It is often used in combination with other drugs to treat various types of cancer, including gastric cancer.

  • Docetaxel

    is a chemotherapy medication that works by preventing cancer cells from dividing. It is part of the FLOT regimen used in this trial to evaluate the safety and tolerability of pembrolizumab in combination with other drugs.

  • Oxaliplatin

    is a chemotherapy drug that is used to treat cancer by damaging the DNA of cancer cells, which stops them from growing and dividing. It is part of the FLOT regimen in this study.

What is already known about the treatment

Pembrolizumab – This medication is administered intravenously and is currently being studied in clinical trials for its effectiveness in treating gastric and gastroesophageal junction adenocarcinoma. It is a well-known immunotherapy drug that has been approved for various cancers. Pembrolizumab works by blocking a protein called PD-1 on the surface of immune cells, which helps the immune system recognize and attack cancer cells more effectively. It is classified as a monoclonal antibody and is part of the broader category of immune checkpoint inhibitors.

Investigated diseases

Gastric and gastroesophageal junction adenocarcinoma – This is a type of cancer that begins in the glandular cells lining the stomach and the area where the stomach meets the esophagus. It typically starts in the innermost layer of the stomach wall and can grow outward through the other layers. As the disease progresses, it may spread to nearby lymph nodes and other organs. Symptoms often include difficulty swallowing, weight loss, and stomach pain. The progression can vary, with some tumors growing slowly while others may spread more rapidly. Understanding the specific behavior of the tumor is crucial for managing the disease.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-509595-42-00Protocol codeMK-3475-585Estimated enrolment1 122 patientsSponsorMerck Sharp & Dohme LLC

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