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A study of JNJ-78278343 and docetaxel compared to docetaxel and prednisone in patients with metastatic castration-resistant prostate cancer

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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 individuals with Metastatic Castration-resistant Prostate Cancer, a type of prostate cancer that has spread to other parts of the body and no longer responds to hormone therapy. The purpose of the study is to compare the effectiveness of a new combination treatment against a standard treatment option.

Participants in the study will receive different combinations of medications. One group will be given JNJ-78278343, also known as pasritamig, which is a type of agent designed to redirect T-cells, which are cells in the immune system that help fight disease, to target specific markers on cancer cells. This is administered alongside docetaxel, a chemotherapy medication given through an intravenous infusion, which is a liquid delivered directly into a vein. Another group will receive only docetaxel. Some participants may also take prednisone, a type of steroid medication, as part of their treatment regimen.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Study participation and treatment assignment

    After joining the study, a randomization process occurs. this means an assignment is made to one of two different treatment groups to determine which medications are received.

    The first group receives pasritamig (jnj-78278343) and docetaxel. pasritamig is an agent that directs t-cells (a type of white blood cell that helps the body fight disease) toward specific targets, and docetaxel is an intravenous infusion (medicine delivered directly into a vein through a tube).

  2. Step 2

    Alternative treatment group

    The second group receives only docetaxel, which is administered as an intravenous infusion.

  3. Step 3

    Additional medication

    The treatment may also include prednisone, which is an oral tablet (medicine taken by mouth).

  4. Step 4

    Monitoring for disease progression

    During the trial, the time until radiographic disease progression is monitored. this involves checking if the cancer grows or spreads using scans such as ct (computed tomography), mri (magnetic resonance imaging), or bone scans.

    The process continues until radiographic progression is observed or death occurs.

Who can join the trial?

11 criteria

  • You must be a male.
  • You must be between the ages of 18 and 50.
  • Your cancer must be showing signs of growing or spreading, which means having at least one of the following:
  • A PSA level (a protein used to track prostate cancer) of 2 or higher that has increased during two separate tests taken at least one week apart.
  • New signs of cancer or lesions (abnormal areas of tissue) appearing in your lymph nodes, bones, or viscera (internal organs like the liver or lungs) as seen on medical scans.
  • You must have already tried and progressed on at least one ARPI (a type of hormone therapy that stops cancer growth) but must not have used more than two different types of these drugs.
  • You must have stopped taking ARPI medication before joining the study.
  • Your hemoglobin (a protein in red blood cells that carries oxygen) must be at least 9.0 g/dL.
  • Your neutrophils (a type of white blood cell that helps fight infection) must be at least 1.5 x 10^9/L.
  • Your platelets (cells that help your blood clot to stop bleeding) must be at least 100 x 10^9/L.
  • You must not have received a blood transfusion or used growth factors (medicines that increase blood cell counts) within 14 days before starting the study.

Who cannot join the trial?

5 criteria

  • You cannot participate if you have already received cytotoxic chemotherapy, which is a type of strong medicine used to kill fast-growing cancer cells, for your prostate cancer.
  • You are not eligible if you have previously used CD3 redirector therapies, radiopharmaceutical agents (medicines that use radiation to treat cancer), or immunotherapy agents (treatments that help your immune system fight cancer) for prostate cancer.
  • You cannot join the study if you have taken PARP inhibitors, which are a specific type of targeted medicine used to treat certain cancers, unless they were used specifically for BRCA1/2 mutations.
  • You are excluded if you have already used any other investigational agent, which refers to a drug or treatment that is still being studied and is not yet widely available.
  • If you have known BRCA 1/2 mutations (changes in your genes that can increase cancer risk), you cannot participate unless you have already tried a PARP inhibitor and it was either not available to you or was not safe for you to use.
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Investigated drugs

  • Docetaxel

    is a type of chemotherapy medicine that is given through a vein. It works by stopping cancer cells from growing and dividing.

  • JNJ-78278343

    is an experimental medicine being tested in this study. It is designed to help the body's own immune system, specifically T-cells, find and attack cancer cells that have a certain protein on their surface.

  • Prednisone

    is a steroid medication that is taken by mouth. In this study, it is used as a comparison treatment alongside the chemotherapy.

What is already known about the treatment

  • Prednisone

    This medication is taken as a pill by mouth and is a well-established corticosteroid used to manage various inflammatory and autoimmune conditions. In cancer treatment, it is often used to help reduce side effects or manage certain symptoms. It works by entering cells and changing how certain genes are expressed, which ultimately lowers inflammation and suppresses the immune response.

  • Docetaxel

    This drug is administered as a liquid through an intravenous infusion directly into a vein and is a widely used chemotherapy agent for various types of cancer. It functions by binding to and stabilizing microtubules, which are the structural supports within cells, thereby preventing cancer cells from dividing and growing. It belongs to a class of drugs known as taxanes.

  • Pasritamig

    This is an experimental investigational drug being studied in clinical trials and is administered as a solution through an intravenous infusion. It is being tested for its ability to treat advanced prostate cancer by acting as a T-cell-redirecting agent. At a molecular level, it works by targeting a specific protein called human kallikrein 2 to guide the body's own immune cells to find and attack cancer cells.

Investigated diseases

Metastatic Castration-resistant Prostate Cancer - This is an advanced form of prostate cancer that has spread to other parts of the body. It occurs when the cancer continues to grow even though hormone therapy has lowered testosterone levels to very low amounts. The disease involves cancer cells that no longer respond to the standard methods of reducing male hormones. As the condition progresses, the cancer cells can multiply and move into bones or other organs. This stage represents a more advanced phase of the disease where the cancer becomes less sensitive to typical hormonal controls.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522713-29-00Protocol code78278343PCR3003Estimated enrolment800 patientsSponsorJanssen Cilag International

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).