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Study of PF-06821497 and Enzalutamide for Men with Advanced Prostate Cancer Resistant to Hormone 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 condition known as metastatic castration-resistant prostate cancer. This is 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 investigating the effects of a new investigational medicine called PF-06821497, also known as Mevrometostat, in combination with another medication called enzalutamide. Enzalutamide is a treatment that is already used to manage prostate cancer. The purpose of the study is to see if the combination of PF-06821497 and enzalutamide is more effective than enzalutamide with a placebo in slowing down the progression of the cancer.

Participants in the study will be randomly assigned to receive either the combination of PF-06821497 and enzalutamide or enzalutamide with a placebo. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the investigational medicine and who is receiving the placebo. This helps ensure that the results are not influenced by expectations about the treatment. The study will last for a period of time, during which participants will take the medications orally in the form of capsules or tablets. Regular check-ups and assessments will be conducted to monitor the participants' health and the progression of the cancer.

The main goal of the study is to determine if the combination of PF-06821497 and enzalutamide can extend the time before the cancer worsens compared to the use of enzalutamide with a placebo. The study will also look at other outcomes, such as overall survival and the time it takes for the cancer to start growing again. Participants' experiences with pain and quality of life will also be assessed throughout the study. This research aims to provide valuable information that could lead to improved treatment options for men 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

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes verifying age, medical history, and current health status.

    A diagnosis of metastatic castration-resistant prostate cancer is confirmed through medical records and imaging tests.

  2. Step 2

    Randomization

    Participants are randomly assigned to one of two groups: one receiving the investigational medicine PF-06821497 with enzalutamide, and the other receiving a placebo with enzalutamide.

    This process ensures that the study results are unbiased.

  3. Step 3

    Medication administration

    Participants take the assigned medication orally. Enzalutamide is administered as a tablet.

    The investigational medicine PF-06821497 or placebo is also administered orally in tablet form.

    The dosage and frequency are determined by the study protocol and are monitored by the study team.

  4. Step 4

    Regular monitoring

    Participants attend regular visits to monitor health status and response to treatment.

    These visits include physical examinations, blood tests, and imaging studies to assess the progression of the disease.

  5. Step 5

    Assessment of treatment response

    The effectiveness of the treatment is evaluated by measuring progression-free survival, which is the time during and after the treatment that the patient lives with the disease without it getting worse.

    Other assessments include overall survival, time to pain progression, and changes in quality of life.

  6. Step 6

    Completion of study participation

    Participants complete the study after a specified period or if the disease progresses significantly.

    Final assessments are conducted to gather data on the long-term effects and benefits of the treatment.

Who can join the trial?

9 criteria

  • Male participants aged 18 years or older at the time of screening.
  • Confirmed diagnosis of prostate cancer, specifically a type called adenocarcinoma, without small cell features. If there is no previous diagnosis, a new biopsy is needed to confirm it.
  • The cancer has spread to the bones or soft tissues, as shown by specific scans like a bone scan or CT/MRI scan.
  • Participants must have low levels of testosterone, either due to surgery or medication, with a specific measurement of 50 ng/dL or less.
  • The disease must be getting worse despite low testosterone levels, shown by one or more of the following:
    • Increasing levels of a protein called **prostate-specific antigen (PSA)**, with at least two rising measurements taken at least 7 days apart within the last year.
    • Worsening of soft tissue disease as defined by specific criteria called **RECIST 1.1**.
    • Worsening of bone disease with two or more new bone lesions, as shown by a whole-body bone scan.
    • Any side effects from previous treatments must have improved to a mild level or returned to the level they were before treatment, except for certain side effects like hair loss or nerve damage that are not considered a safety risk.
    • Participants must have a good level of daily functioning, as measured by a scale called **ECOG performance status**, with a score of 0 or 1, and a life expectancy of at least 12 months as assessed by the investigator.

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 can participate. Female patients are not eligible.
  • Patients who are considered part of a vulnerable population, such as those unable to give informed consent, are not eligible.
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Investigated drugs

  • PF-06821497 (Mevrometostat)

    is an experimental medication being studied for its potential to treat metastatic castration-resistant prostate cancer. It is being tested to see if it can help slow down the progression of the disease when used in combination with another medication.

  • Enzalutamide

    is a medication used to treat prostate cancer. It works by blocking the effects of male hormones that can promote the growth of cancer cells. In this study, enzalutamide is used in combination with PF-06821497 to see if the combination is more effective than enzalutamide alone.

What is already known about the treatment

  • Mevrometostat

    This medication is administered orally and is currently being studied in clinical trials for its effectiveness in treating metastatic castration-resistant prostate cancer. It is not yet widely used in standard medical practice, as it is still under investigation. The main therapeutic indication is to potentially improve outcomes in prostate cancer that has spread and is resistant to hormonal therapy. Mevrometostat works by inhibiting specific enzymes involved in cancer cell growth, aiming to slow down or stop the progression of the disease. It is classified as an enzyme inhibitor in pharmacology.

  • Enzalutamide

    This medication is also taken orally and is already approved for use in treating prostate cancer, specifically metastatic castration-resistant prostate cancer. It is well-documented in medical literature and is commonly used in clinical practice. Enzalutamide is primarily indicated for patients whose prostate cancer has progressed despite hormone therapy. It works by blocking the action of male hormones that can promote the growth of cancer cells. Pharmacologically, it is classified as an androgen receptor inhibitor.

Investigated diseases

Metastatic Castration-Resistant Prostate Cancer – This is a type of prostate cancer that continues to progress despite treatments that lower testosterone levels. It has spread to other parts of the body, such as bones or lymph nodes, beyond the prostate gland. The cancer cells in this condition are no longer responsive to hormonal therapy aimed at reducing male hormones. As the disease advances, it may cause symptoms like bone pain or urinary issues. The progression of the disease can vary, with some patients experiencing a more rapid spread than others. It is a challenging condition that requires ongoing management to control symptoms and slow progression.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-511652-40-00Protocol codeC2321003Estimated enrolment900 patientsSponsorPfizer Inc.

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