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Study of Pembrolizumab, Vibostolimab, and Favezelimab for Patients with High-Risk Non-Muscle Invasive Bladder Cancer Unresponsive to BCG Therapy

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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 a type of bladder cancer known as Non-Muscle Invasive Bladder Cancer (NMIBC). This form of cancer affects the bladder but does not invade the muscle layer. The study is investigating the effectiveness and safety of a treatment called pembrolizumab, which is also known by its code name MK-3475. Pembrolizumab is a medication that helps the immune system fight cancer cells. In addition to pembrolizumab, the study is also testing combinations with other investigational agents, specifically MK-7684A and MK-4280A. These investigational agents include substances like vibostolimab and favezelimab, which are designed to enhance the body's immune response against cancer.

The purpose of this study is to evaluate how well these treatments work in patients with high-risk NMIBC that has not responded to a common therapy called Bacillus Calmette-Guerin (BCG). The study aims to see if these treatments can help eliminate the cancer or prevent it from getting worse. Participants in the study will receive the treatments through an intravenous infusion, which means the medication is given directly into a vein. The study will monitor the participants over a period of time to assess the response to the treatment and any side effects that may occur.

Throughout the study, participants will undergo regular check-ups, including procedures like cystoscopy (a test that allows doctors to look inside the bladder), cytology (examining cells from the bladder), and imaging tests to track the progress of the disease. The study will also evaluate the complete response rate, which refers to the absence of detectable cancer, and the disease-free survival rate, which measures how long participants remain free from cancer. The trial is expected to continue until 2030, providing valuable insights into the potential benefits of these treatments for patients with high-risk NMIBC.

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

    Initial assessment

    Upon joining the clinical trial, an initial assessment will be conducted. This includes a review of medical history and a physical examination to confirm eligibility based on specific criteria such as a diagnosis of high-risk non-muscle-invasive bladder cancer.

    Additional tests may include a cystoscopy, which is a procedure to look inside the bladder, and imaging tests to evaluate the current state of the disease.

  2. Step 2

    Treatment initiation

    The treatment phase begins with the administration of the medication pembrolizumab through an intravenous infusion. This means the medication is given directly into a vein.

    The dosage and frequency of the medication will be determined by the study protocol and communicated by the healthcare team.

  3. Step 3

    Combination therapy

    In addition to pembrolizumab, other investigational agents such as MK-7684A or MK-4280A may be administered. These are also given through intravenous infusion.

    The combination therapy aims to evaluate the anti-tumor activity and is part of the study's main objectives.

  4. Step 4

    Regular monitoring

    Throughout the trial, regular monitoring will occur to assess the response to treatment. This includes repeated cystoscopies, imaging tests, and possibly biopsies to check for the presence of cancer cells.

    The healthcare team will also monitor for any side effects or adverse events related to the treatment.

  5. Step 5

    Follow-up assessments

    Follow-up assessments are scheduled at specific intervals, such as 3, 6, and 12 months, to evaluate the complete response rate and disease-free survival.

    These assessments help determine the effectiveness of the treatment and any long-term effects.

  6. Step 6

    End of trial

    At the end of the trial, a final evaluation will be conducted to summarize the treatment outcomes and any ongoing health considerations.

    Participants may receive guidance on further treatment options or follow-up care based on the results of the trial.

Who can join the trial?

9 criteria

  • Must have a confirmed diagnosis of high-risk non-muscle-invasive bladder cancer. This includes specific types like T1, high-grade Ta, or carcinoma in situ (CIS). If the tumor has different types of cells, the main type should be transitional cell.
  • The disease must be fully removed at the start of the study, but some remaining CIS is acceptable.
  • Must have BCG-unresponsive high-risk non-muscle-invasive bladder cancer after receiving enough BCG therapy. BCG is a treatment used for bladder cancer.
  • Cannot have surgery to remove the bladder (radical cystectomy) or must have chosen not to have this surgery.
  • Must have tissue available from a new biopsy of a tumor that has not been treated with radiation before.
  • Must have an ECOG performance status of 0, 1, or 2. This is a scale that measures how well you can perform daily activities.
  • Must have adequate organ function, meaning your organs are working well enough to participate in the study.
  • Female participants who can have children must have a negative pregnancy test and agree to use a reliable method of birth control.
  • Male participants must agree to use a reliable method of birth control.

Who cannot join the trial?

8 criteria

  • Patients who have a different type of bladder cancer that is not classified as Non-Muscle Invasive Bladder Cancer (NMIBC) cannot participate. NMIBC is a type of bladder cancer that has not spread into the muscle layer of the bladder.
  • Patients who have other serious medical conditions that could interfere with the study or make it unsafe for them to participate may be excluded.
  • Patients who are currently receiving other treatments for cancer that could interfere with the study may not be eligible.
  • Patients who have had a recent major surgery or a significant injury that has not fully healed may be excluded.
  • Patients who are pregnant or breastfeeding cannot participate in the study.
  • Patients who have a history of severe allergic reactions to similar medications used in the study may be excluded.
  • Patients who are unable to follow the study procedures or attend the required visits may not be eligible.
  • Patients who have participated in another clinical trial recently may be excluded to avoid interference with the study results.
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Investigated drugs

  • Pembrolizumab

    is a type of medication known as an immunotherapy. It works by helping your immune system recognize and attack cancer cells. In this trial, it is being used to see if it can help treat a type of bladder cancer that has not responded to other treatments.

  • MK-7684A

    is an investigational drug, which means it is still being studied and is not yet approved for general use. It is being tested to see if it can help treat bladder cancer by working with your immune system to fight the cancer cells.

  • MK-4280A

    is another investigational drug in this trial. Like MK-7684A, it is being studied to determine if it can help your immune system target and destroy cancer cells in the bladder. This medication is part of the research to find new ways to treat bladder cancer that has not responded to standard therapies.

What is already known about the treatment

Pembrolizumab – Pembrolizumab is administered as an intravenous infusion, meaning it is given directly into a vein through a needle. It is currently being studied in clinical trials for its effectiveness and safety in treating high-risk non-muscle-invasive bladder cancer (NMIBC) that does not respond to Bacillus Calmette-Guerin (BCG) therapy. The main therapeutic use of pembrolizumab is to help the immune system recognize and attack cancer cells. At the molecular level, it works by blocking a protein called PD-1 on immune cells, which helps the immune system to better detect and fight cancer cells. Pembrolizumab is classified as an immune checkpoint inhibitor, a type of drug that helps the body's immune system fight cancer.

Investigated diseases

Non-Muscle Invasive Bladder Cancer (NMIBC) – This type of bladder cancer is characterized by the presence of cancerous cells in the bladder lining that have not invaded the muscle layer. It often presents with symptoms such as blood in the urine or frequent urination. The disease progresses by potentially growing into larger tumors or spreading to other parts of the bladder lining. Over time, if not managed, it may develop into a more invasive form of bladder cancer. Monitoring typically involves regular cystoscopy to check for tumor recurrence or progression. The progression of NMIBC can vary, with some cases remaining stable while others may become more aggressive.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2022-502526-41-00Protocol codeMK-3475-057Estimated enrolment356 patientsSponsorMerck Sharp & Dohme LLC

sourced from the EU Clinical Trials Register and site verification

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).