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Study of Pembrolizumab, Vibostolimab, and Belzutifan for Patients with Metastatic Castration-Resistant Prostate Cancer

Verified siteRegistered drugNo placebo
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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 Metastatic Castration-Resistant Prostate Cancer, a type of prostate cancer that continues to grow and spread even when the amount of testosterone in the body is reduced to very low levels. The study is testing a combination of therapies that include Pembrolizumab (also known as MK-3475), which is a type of immunotherapy that helps the immune system fight cancer. Other medications being studied in combination with Pembrolizumab include Abiraterone, Enzalutamide, Docetaxel, Carboplatin, Etoposide, Olaparib, Lenvatinib, and Belzutifan. Some of these medications are given as tablets, while others are administered through an infusion into a vein.

The purpose of this study is to evaluate the safety and effectiveness of these combination therapies. Participants will receive either the combination therapy or a placebo. The study will monitor the participants' response to the treatment, including any changes in their prostate-specific antigen (PSA) levels, which is a marker used to track prostate cancer. The study will also look at how long the participants live and how long they respond to the treatment. Participants will be closely monitored for any side effects or adverse events during the study.

The study will take place over several years, with participants receiving treatment and being monitored regularly. The goal is to find out if these combination therapies can help control the cancer and improve the quality of life for those affected by this type of prostate cancer. The study will provide valuable information that could lead to new treatment options for patients with metastatic castration-resistant prostate cancer.

The research process

The trial runs in 6 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, the participant will be assigned to a specific cohort based on their medical history and previous treatments for metastatic castration-resistant prostate cancer (mCRPC).

  2. Step 2

    Initial assessment

    An initial assessment will be conducted to evaluate the participant's current health status and eligibility for the trial. This includes providing tumor tissue samples and confirming ongoing prostate cancer progression.

  3. Step 3

    Treatment administration

    Participants will receive a combination of medications, which may include pembrolizumab, vibostolimab, abiraterone, enzalutamide, docetaxel, carboplatin, etoposide, olaparib, lenvatinib, belzutifan, prednisolone, and dexamethasone. The administration route varies, including oral use and intravenous infusion, depending on the specific medication.

  4. Step 4

    Monitoring and follow-up

    Regular monitoring will be conducted to assess the safety and effectiveness of the treatment. This includes tracking the prostate-specific antigen (PSA) levels and any adverse events experienced by the participant.

  5. Step 5

    Completion of treatment

    The treatment phase will continue until the participant completes the study or if any adverse events necessitate discontinuation. The estimated end date for the trial is October 22, 2027.

  6. Step 6

    Final evaluation

    A final evaluation will be conducted to determine the overall response to the treatment, including the objective response rate and any changes in disease progression.

Who can join the trial?

9 criteria

  • Must have **metastatic castration-resistant prostate cancer**. This means the cancer has spread to other parts of the body and is not responding to treatments that lower testosterone.
  • Must be male.
  • Must be able to provide a sample of tumor tissue from a site that has not been treated with radiation.
  • Must have cancer progression within 6 months before screening, as determined by the doctor, using specific criteria like rising PSA levels or new bone lesions.
  • Must have ongoing treatment to lower testosterone levels, with specific hormone treatments started at least 4 weeks before the study and continued throughout the study.
  • If receiving bone-strengthening therapy, must be on stable doses for at least 4 weeks before the study.
  • Must agree to use contraception or be abstinent from heterosexual intercourse during the study and for a specific time after the last dose of study medication, unless confirmed to be unable to produce sperm.
  • Must have a performance status of 0, 1, or 2 on the **Eastern Cooperative Oncology Group (ECOG) Performance Scale** for certain groups. This scale measures how well you can perform daily activities.
  • Must have received specific prior treatments depending on the cohort, such as certain chemotherapy or hormonal therapies.

Who cannot join the trial?

3 criteria

  • Patients who do not have Metastatic Castration-Resistant Prostate Cancer cannot participate. This is a type of prostate cancer that has spread to other parts of the body and does not respond to treatments that lower testosterone.
  • Only male patients are eligible for this study.
  • Patients who are part of a vulnerable population, such as those who cannot make decisions for themselves, are not eligible.
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Investigated drugs

Pembrolizumab (MK-3475) is a medication used in this trial to treat metastatic castration-resistant prostate cancer. It works by helping the immune system recognize and attack cancer cells. Pembrolizumab is often used in combination with other therapies to enhance its effectiveness in fighting cancer.

What is already known about the treatment

Pembrolizumab – Pembrolizumab is administered as an intravenous infusion, typically given in a clinical setting. It is currently being studied in clinical trials for its effectiveness in treating metastatic castration-resistant prostate cancer. The medication is primarily used to help the immune system detect and fight cancer cells. It works by blocking a specific protein on the surface of immune cells, which allows these cells to better recognize and attack cancer cells. Pembrolizumab is classified as an immune checkpoint inhibitor, a type of immunotherapy.

Investigated diseases

Metastatic Castration-Resistant Prostate Cancer – This is a type of prostate cancer that continues to grow and spread to other parts of the body despite treatments that lower testosterone levels. It is characterized by the cancer's ability to resist hormonal therapy, which is typically used to slow its progression. The disease often spreads to bones, lymph nodes, and other organs, leading to various symptoms depending on the areas affected. Patients may experience increased levels of prostate-specific antigen (PSA) in the blood, which is a marker used to monitor the disease's activity. Over time, the cancer may cause pain, urinary issues, and other complications as it progresses.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-506987-15-00Protocol codeMK-3475-365Estimated enrolment1 205 patientsSponsorMerck Sharp & Dohme LLC

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