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Study of xaluritamig plus abiraterone for men with metastatic castration-resistant prostate cancer who have not received chemotherapy

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 study involves people with metastatic castration-resistant prostate cancer, which is an advanced form of prostate cancer that has spread to other parts of the body and no longer responds to treatments that lower testosterone levels. The study will test a combination of two treatments. The first treatment is xaluritamig, also known as AMG 509, which is an experimental medicine given through a vein. This medicine will be combined with abiraterone acetate, which is taken by mouth as a tablet. The study will compare this combination against a treatment chosen by the doctor, which could be docetaxel given through a vein, cabazitaxel given through a vein, or abiraterone acetate alone taken by mouth. All of these medicines are designed to fight cancer cells. The study will also use siltuximab, known as Sylvant, which is given through a vein for certain situations during the study.

The purpose of this study is to find out if the combination of xaluritamig plus abiraterone helps people with this type of prostate cancer live longer compared to the treatment chosen by their doctor. The study will also look at how long the cancer stays under control, whether the cancer shrinks or disappears, how long any improvement lasts, and how the treatments affect quality of life and symptoms such as pain. Additionally, the study will check for any unwanted effects of the treatments and measure how the body processes these medicines over time.

Participants in this study will be randomly assigned to receive either the combination of xaluritamig plus abiraterone or one of the treatments chosen by their doctor. During the study, participants will have regular check-ups where doctors will use imaging tests like computed tomography scans, magnetic resonance imaging scans, or bone scans to see how the cancer is responding to treatment. Blood tests will be done to check organ function and measure levels of prostate-specific antigen, which is a substance in the blood that can indicate how the cancer is responding. Participants will also be asked to complete questionnaires about their pain levels, side effects, and overall quality of life throughout the study. The study will continue until enough information is collected to determine which treatment approach works better.

The research process

The trial runs in 13 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Treatment assignment

    Upon entering the study, you will be randomly assigned to one of two treatment groups. This process is called randomization and ensures fair distribution of participants.

    You will receive either xaluritamig plus abiraterone acetate or one of the investigator's choice treatments, which may include docetaxel, cabazitaxel, or abiraterone acetate alone.

  2. Step 2

    Baseline imaging and assessments

    Before starting treatment, imaging scans will be performed. These may include computed tomography (a detailed x-ray scan), magnetic resonance imaging (a scan using magnets and radio waves), or a bone scan.

    These scans must be completed within 28 days before enrollment to confirm the presence of cancer that has spread to other parts of the body.

  3. Step 3

    Treatment administration - Group 1

    If you are assigned to receive xaluritamig plus abiraterone acetate, you will receive both medications throughout the study period.

    Xaluritamig will be given through a vein (intravenous infusion). The specific dosage, frequency, and duration will be determined by the study protocol.

    Abiraterone acetate will be taken by mouth (oral administration). The specific dosage, frequency, and duration will be determined by the study protocol.

    You will continue ongoing androgen-deprivation therapy, which is treatment that lowers male hormone levels, to maintain castrate levels of testosterone in your blood.

  4. Step 4

    Treatment administration - Group 2

    If you are assigned to receive one of the investigator's choice treatments, you will receive one of the following options as determined by your doctor.

    Option A: Docetaxel will be given through a vein (intravenous infusion). The specific dosage, frequency, and duration will be determined by the study protocol.

    Option B: Cabazitaxel will be given through a vein (intravenous infusion). The specific dosage, frequency, and duration will be determined by the study protocol. This option is only available if you previously received no more than 6 cycles of docetaxel for earlier stage disease.

    Option C: Abiraterone acetate will be taken by mouth (oral administration). The specific dosage, frequency, and duration will be determined by the study protocol.

    You will continue ongoing androgen-deprivation therapy, which is treatment that lowers male hormone levels, to maintain castrate levels of testosterone in your blood.

  5. Step 5

    Additional medication option

    In some cases, siltuximab may be administered. This medication is given through a vein (intravenous infusion).

    The specific dosage, frequency, and duration will be determined by the study protocol if this medication is included in your treatment plan.

  6. Step 6

    Regular monitoring visits

    Throughout the study, you will attend regular visits for monitoring and assessments.

    Blood samples will be collected to measure prostate-specific antigen levels (a protein produced by the prostate that can indicate disease status) and to check organ function.

    Your testosterone levels will be monitored to ensure they remain at castrate levels (less than 50 nanograms per deciliter or less than 1.7 nanomoles per liter).

    Physical examinations will be performed to assess your overall health and performance status (your ability to carry out daily activities).

  7. Step 7

    Disease assessment imaging

    Periodic imaging scans will be performed to evaluate how the cancer is responding to treatment.

    These scans will assess whether the disease is stable, improving, or progressing according to standardized criteria called RECIST 1.1 (Response Evaluation Criteria in Solid Tumors).

    Bone scans may also be performed to monitor disease in the bones.

  8. Step 8

    Safety monitoring

    Throughout the study, any side effects or adverse events you experience will be recorded and monitored.

    You will be asked to report any new symptoms or changes in your health condition.

    Serious adverse events will be carefully tracked and managed according to medical standards.

  9. Step 9

    Quality of life assessments

    You will complete questionnaires at regular intervals to assess your quality of life and symptom burden.

    These include the Brief Pain Inventory-Short Form to measure pain levels and how pain interferes with daily activities.

    The Functional Assessment of Cancer Therapy-Prostate questionnaire will assess your physical, emotional, and functional well-being.

    The EQ-5D-5L questionnaire will measure your overall health status and quality of life.

    You will also complete questions about side effects you may be experiencing using a patient-reported outcomes tool.

  10. Step 10

    Blood sample collection for research

    Blood samples will be collected at specific times to measure drug levels in your bloodstream.

    For xaluritamig, measurements will include maximum concentration, minimum concentration, and how the drug accumulates in your body over time.

    For abiraterone, drug concentrations will be measured at the end of dosing intervals.

    Additional blood samples will be collected to check for antibodies your body may develop against xaluritamig.

  11. Step 11

    Treatment continuation

    You will continue receiving your assigned treatment until the disease progresses, unacceptable side effects occur, or other discontinuation criteria are met.

    The study will monitor the time until you require a subsequent therapy after stopping the study treatment.

    The occurrence of symptomatic skeletal events (bone-related complications causing symptoms) will be tracked.

  12. Step 12

    End of treatment assessments

    When you stop receiving study treatment, final assessments will be performed.

    These will include physical examination, blood tests, and imaging scans to document your disease status.

    Quality of life questionnaires will be completed to capture your final assessment while on study.

  13. Step 13

    Follow-up period

    After completing treatment, you will enter a follow-up period where your health status will continue to be monitored.

    Information about any subsequent cancer treatments you receive will be collected.

    Long-term outcomes, including overall survival (how long you live after starting the study), will be tracked.

    The study is expected to continue collecting data through August 2032.

Who can join the trial?

11 criteria

  • You must provide your agreement to participate in the study before any study procedures begin
  • Your organs such as liver, kidneys, and bone marrow must be working well enough
  • You must be 18 years old or older at the time of signing the agreement to join the study
  • You must have a confirmed diagnosis of adenocarcinoma of the prostate, which is a type of prostate cancer confirmed by tissue examination
  • You must have metastatic castration-resistant prostate cancer, which means prostate cancer that has spread to other parts of the body and continues to grow despite treatment that lowers male hormones, with at least one area of spread visible on scans such as CT scan (a detailed x-ray), MRI (a scan using magnets), or bone scan taken within 28 days before joining the study
  • Your cancer must show signs of getting worse, based on specific measurement criteria
  • You must have had surgery to remove your testicles or be receiving ongoing treatment to lower male hormones, and your blood testosterone level (a male hormone) must be very low (less than 50 ng/dL or less than 1.7 nmol/L)
  • Your cancer must have previously worsened while taking one, and only one, type of medicine that blocks male hormone receptors (either enzalutamide, apalutamide, or darolutamide)
  • If you are planned to receive cabazitaxel (a type of chemotherapy), you must have received no more than 6 treatment cycles of docetaxel (another type of chemotherapy) when your cancer was hormone-sensitive and had spread
  • You must have an ECOG performance status of 0 or 1, which means you are able to carry out normal activities or have only minor restrictions in physically demanding activities
  • You must be male

Who cannot join the trial?

4 criteria

  • Women cannot participate in this study, as it is only for male patients
  • Patients who do not have metastatic castration-resistant prostate cancer, which means prostate cancer that has spread to other parts of the body and no longer responds to treatments that lower testosterone levels
  • Patients who are outside the specified age range for this study
  • Patients who do not meet the general health requirements needed to safely participate in the study
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Investigated drugs

  • Xaluritamig

    is an investigational medication being tested in this clinical trial for the treatment of prostate cancer that has spread to other parts of the body and no longer responds to hormone therapy. This medication is given together with abiraterone in one of the treatment groups in the study.

  • Abiraterone

    is a medication used to treat prostate cancer. It works by blocking the production of certain hormones that can help prostate cancer cells grow. In this study, it is used both in combination with xaluritamig and as one of the possible treatment options that the doctor can choose.

  • Docetaxel

    is a chemotherapy medication that is used to treat various types of cancer, including prostate cancer. It works by stopping cancer cells from dividing and growing. In this study, it is one of the treatment options that the doctor can choose for participants.

  • Cabazitaxel

    is a chemotherapy medication used to treat prostate cancer. It works similarly to docetaxel by preventing cancer cells from dividing. In this study, it is one of the treatment options that the doctor can choose for participants.

What is already known about the treatment

  • Xaluritamig

    Xaluritamig is an investigational medication currently being studied in clinical trials for the treatment of metastatic castration-resistant prostate cancer in patients who have not yet received chemotherapy. This drug is being tested in combination with abiraterone to see if it can help patients live longer compared to standard treatment options. Xaluritamig works by engaging the immune system to attack cancer cells, specifically by connecting immune cells to prostate cancer cells so they can be destroyed more effectively. It is administered as part of an experimental treatment approach and is not yet approved for general medical use.

  • Abiraterone

    Abiraterone is an approved oral medication used to treat advanced prostate cancer that no longer responds to hormone therapy. It works by blocking an enzyme called CYP17, which is needed for the body to produce testosterone and other hormones that can fuel prostate cancer growth. By reducing the levels of these hormones throughout the body, including in the prostate cancer cells themselves, abiraterone helps slow down or stop the cancer from growing. This medication is taken by mouth as tablets, usually once daily on an empty stomach, and is typically given along with a steroid medication called prednisone.

  • Docetaxel

    Docetaxel is a chemotherapy medication approved for treating various types of cancer, including metastatic castration-resistant prostate cancer. It is given through an intravenous infusion directly into a vein, usually once every three weeks, and works by interfering with cancer cells' ability to divide and multiply. Specifically, docetaxel disrupts the internal structure of cells that helps them maintain their shape and divide, causing the cancer cells to stop growing and eventually die. This medication has been widely used for many years and is considered a standard treatment option for advanced prostate cancer.

  • Cabazitaxel

    Cabazitaxel is a chemotherapy drug administered intravenously that is approved for treating metastatic castration-resistant prostate cancer, particularly in patients who have already received other chemotherapy treatments. Similar to docetaxel, it works by disrupting the internal scaffolding of cancer cells that is necessary for cell division, preventing the cancer cells from multiplying and causing them to die. Cabazitaxel is given as an infusion into a vein once every three weeks and is often used when prostate cancer continues to progress despite previous treatments. This medication is part of a class of chemotherapy drugs called taxanes and represents an important treatment option for advanced prostate cancer.

Investigated diseases

Metastatic Castration-Resistant Prostate Cancer – This is an advanced form of prostate cancer that has spread beyond the prostate gland to other parts of the body and continues to grow despite treatment that lowers testosterone levels. The prostate is a small gland in men that produces fluid for semen, and cancer occurs when cells in this gland grow uncontrollably. In castration-resistant cases, the cancer no longer responds to hormone therapy designed to reduce male hormones that fuel cancer growth. As the disease progresses, cancer cells spread through the bloodstream or lymphatic system to bones, lymph nodes, liver, lungs, or other organs. Patients may experience bone pain, difficulty urinating, fatigue, and weight loss as the cancer advances. The metastatic nature means the cancer has established itself in distant sites away from the original tumor location.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-520555-89-00Protocol code20230239Estimated enrolment750 patientsSponsorAmgen Inc.

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