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Study of talazoparib and enzalutamide combination in men with DDR gene mutated metastatic castration-sensitive prostate cancer

Fast replyRegistered drugNo placebo
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What is this trial about?

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

This study focuses on men with metastatic castration-sensitive prostate cancer who have specific genetic mutations in their DNA repair genes. The research examines the effectiveness of combining two medications: talazoparib and enzalutamide. Metastatic means the cancer has spread from the prostate to other parts of the body, while castration-sensitive means the cancer still responds to treatments that lower testosterone levels.

The purpose of this study is to determine if adding talazoparib to enzalutamide treatment works better than using enzalutamide with a placebo in treating this type of prostate cancer. The study uses DNA repair gene mutations testing to identify suitable participants. During the study, participants will receive either the combination of talazoparib and enzalutamide or enzalutamide with a placebo.

Throughout the treatment period, which may last up to 24 months, participants will continue to receive hormone therapy that reduces testosterone levels. The study will monitor how the cancer responds to treatment through regular medical examinations and imaging tests. These tests will help determine if the cancer is stable, improving, or getting worse.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial medication assignment

    You will be randomly assigned to one of two treatment groups:

    Group 1: Talazoparib capsules + Enzalutamide (Xtandi) 40 mg soft capsules

    Group 2: Placebo capsules + Enzalutamide (Xtandi) 40 mg soft capsules

    Both medications are taken by mouth

  2. Step 2

    Hormone therapy requirement

    You must continue taking your prescribed hormone therapy (ADT) throughout the entire study

    This involves regular injections of medication that lowers testosterone levels, unless you have had previous surgery to remove both testicles

  3. Step 3

    Regular health monitoring

    Your cancer progression will be monitored through regular imaging scans

    Doctors will check for changes in both soft tissue using CT or MRI scans

    Bone scans will be performed to check for bone-related changes

  4. Step 4

    Physical condition assessment

    Your overall physical condition will be regularly evaluated using the ECOG scale

    This scale measures your ability to perform daily activities and self-care

  5. Step 5

    Study duration

    The study continues until August 2027

    Your participation may end earlier if your condition changes or as determined by your doctor

Who can join the trial?

10 criteria

  • Must have confirmed prostate cancer (specifically adenocarcinoma type) that has been verified through tissue examination
  • Must undergo testing to confirm specific genetic mutations (called DDR gene mutations) through blood sample or tissue analysis
  • Must be receiving ongoing hormone therapy (ADT) with specific medications, or have had surgical removal of testicles (bilateral orchiectomy). The hormone therapy must continue throughout the study
  • Must have cancer that has spread (metastatic disease) confirmed by:
    • Bone scan showing spread to bones, or
    • CT or MRI scan showing spread to soft tissues
    • Must have good physical functioning ability, scoring either 0 (fully active) or 1 (restricted in physically strenuous activity) on the ECOG performance scale
    • Must be male
    • Must be an adult (18 years or older)
    • Cannot have cancer spread limited to only pelvic lymph nodes
    • Cannot have a condition called superscan (a specific type of bone scan result)

Who cannot join the trial?

15 criteria

  • Prior treatment with PARP inhibitors (medications that block DNA repair in cancer cells)
  • Known active brain or spinal cord metastases (cancer that has spread to brain or spine)
  • Significant heart conditions, including:
    • Heart attack within past 6 months
    • Uncontrolled high blood pressure
    • Unstable heart rhythm problems
    • Severe liver problems or active liver disease
    • Other active cancers requiring treatment (except non-melanoma skin cancer)
    • History of seizures or conditions that may cause seizures
    • Major surgery within 4 weeks before starting the study
    • Any serious medical condition that could interfere with study participation
    • Unable to swallow oral medications
    • Known allergic reactions to the study medications
    • Participation in other clinical trials within 4 weeks before this study
    • Female patients (study is only for male participants)
    • Age below 18 years
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Investigated drugs

  • Talazoparib

    is a medication that belongs to a class of drugs called PARP inhibitors. It works by blocking an enzyme that helps repair damaged DNA in cancer cells, which can help stop cancer cells from growing and dividing. In this trial, it is being studied for treating prostate cancer that has specific genetic mutations.

  • Enzalutamide

    is a hormone therapy medication used to treat prostate cancer. It works by blocking the effects of testosterone and other male hormones that can stimulate prostate cancer growth. This medication helps to slow down or stop the growth of prostate cancer cells.

What is already known about the treatment

  • Talazoparib

    An oral PARP (poly ADP-ribose polymerase) inhibitor medication used in the treatment of metastatic prostate cancer, specifically in patients with DNA damage repair gene mutations. This targeted therapy works by blocking the PARP enzyme, which prevents cancer cells from repairing their damaged DNA, ultimately leading to cancer cell death. The medication is taken in tablet form daily and is typically used in combination with other prostate cancer treatments for enhanced therapeutic effect.

  • Enzalutamide

    An oral androgen receptor inhibitor medication used in the treatment of metastatic castration-sensitive prostate cancer. This hormone therapy works by blocking the effects of testosterone and other male hormones that can stimulate prostate cancer growth. The medication is administered as a daily oral tablet and functions by preventing androgens from binding to their receptors in prostate cancer cells, thereby helping to slow or stop cancer progression.

Investigated diseases

Metastatic Castration-sensitive Prostate Cancer - A condition where prostate cancer has spread beyond the prostate gland to other parts of the body, but still responds to treatments that lower testosterone levels. In this type of cancer, the tumor cells continue to be dependent on male hormones (androgens) for their growth. The cancer typically spreads to lymph nodes, bones, or other organs while maintaining its sensitivity to hormone therapy. This form of prostate cancer represents a stage where the disease has become metastatic but remains responsive to treatments that reduce testosterone levels in the body.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-510809-28-00Protocol codeC3441052Estimated enrolment551 patientsSponsorPfizer Inc.

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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).