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Study of Pembrolizumab with Radiotherapy for Patients with Recurrent Prostate Cancer After Surgery

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 clinical trial is focused on studying a condition known as recurrent prostate cancer. This occurs when prostate cancer returns after initial treatment, such as surgery. The study is investigating a treatment that combines radiotherapy with a medication called pembrolizumab, which is also known by its brand name, KEYTRUDA. Pembrolizumab is a type of medication that helps the immune system fight cancer cells. The purpose of the study is to evaluate how effective and safe this combination treatment is for patients who have a return of prostate cancer, indicated by a rise in a protein called PSA (prostate-specific antigen) after surgery.

Participants in the study will receive the combination of radiotherapy and pembrolizumab. The treatment involves pembrolizumab being given as an infusion, which means it is administered directly into the bloodstream through a vein. The study will monitor participants over a period to see how their PSA levels respond to the treatment and to check for any side effects. The goal is to see if the treatment can lower PSA levels to undetectable amounts and to observe how long patients can go without the cancer progressing.

The study will also look at other factors, such as how long patients can remain free from cancer progression and the overall impact on their quality of life. This will help researchers understand the potential benefits of using pembrolizumab in combination with radiotherapy for treating recurrent prostate cancer. Participants will be closely monitored throughout the study to ensure their safety and to gather important information about the treatment's effects.

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 a review of medical history and a physical examination.

    Imaging tests, such as a PSMA PET-CT or CT abdomen and full-body bone scan, are performed within 50 days prior to registration.

  2. Step 2

    Treatment initiation

    The treatment involves the administration of pembrolizumab, a medication given as an infusion. The specific product used is KEYTRUDA 25 mg/mL concentrate for solution for infusion.

    Pembrolizumab is combined with standard salvage radiation therapy (SRT) to address prostate-specific antigen (PSA) persistence or biochemical recurrence after radical prostatectomy.

  3. Step 3

    Treatment administration

    Pembrolizumab is administered according to the study protocol. The number of doses and the schedule are determined by the study requirements.

    Patients are monitored for any side effects or reactions during and after the infusion.

  4. Step 4

    Monitoring and follow-up

    Regular follow-up appointments are scheduled to monitor the patient's response to treatment. This includes measuring PSA levels and assessing any changes in health status.

    The primary goal is to achieve a complete biochemical response, defined as a PSA level below the limit of detection at week 60 after starting pembrolizumab.

  5. Step 5

    Evaluation of outcomes

    Secondary outcomes include radiographic progression-free survival, PSA-nadir level, and time to PSA-nadir.

    The study also evaluates the number of pembrolizumab doses administered and the time to initiation of any subsequent therapy.

  6. Step 6

    Completion of study

    The study is estimated to conclude by September 30, 2026. Final assessments are conducted to evaluate the overall efficacy and safety of the treatment combination.

    Patients may be asked to complete a functional assessment of cancer therapy using the FACT-P version 4.0 questionnaire.

Who can join the trial?

9 criteria

  • Male patients who are at least 18 years old on the day they sign the consent form.
  • Must have a confirmed diagnosis of a type of prostate cancer called adenocarcinoma, with a return of cancer signs or a specific protein called PSA still present after surgery to remove the prostate.
  • The cancer tissue from the prostate surgery must show a Gleason score between 7 and 10, which is a way to grade prostate cancer. The cancer may have spread to up to 2 nearby lymph nodes.
  • Must have had specific imaging tests within 50 days before joining the study. These tests include a special type of scan called PSMA PET-CT or, alternatively, a CT scan of the abdomen and a full-body bone scan.
  • The PSA level, a protein measured in the blood, must be between 0.2 and 1.0 ng/ml, checked at least six weeks after surgery.
  • Must agree not to undergo a procedure to extract sperm from the testicles for at least 90 days after the last dose of the study medication, pembrolizumab.
  • Must provide written consent to participate, following international guidelines and local laws.
  • Must have a performance status of 0 to 1 on a scale used to assess how well a patient can perform daily activities, known as the Eastern Cooperative Oncology Group (ECOG) performance status.
  • Must have adequate organ function as defined by specific medical criteria.

Who cannot join the trial?

5 criteria

  • Patients who are not male cannot participate.
  • Patients who do not have **recurrent prostate cancer** cannot participate.
  • Patients who have not had a **radical prostatectomy** (a surgery to remove the prostate gland) cannot participate.
  • Patients who do not have **biochemical recurrence** (an increase in prostate-specific antigen or PSA levels after treatment) cannot participate.
  • Patients who are part of a **vulnerable population** (groups that may need special protection) cannot participate.
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Investigated drugs

  • Pembrolizumab

    is a medication used in this trial to help the body's immune system fight cancer cells. It works by blocking a specific protein that can stop the immune system from attacking cancer cells, allowing the immune system to better target and destroy them.

  • Salvage Radiation Therapy (SRT)

    is a treatment used in this trial to target and kill any remaining cancer cells in the prostate area after surgery. It uses high-energy rays to destroy cancer cells and is typically used when there is a recurrence of cancer indicated by rising PSA levels after prostate surgery.

What is already known about the treatment

Pembrolizumab – Pembrolizumab is administered as an intravenous infusion, typically given in a clinical setting. It is currently a well-established medication in the field of oncology, with numerous studies and medical literature supporting its use. The main therapeutic indication for pembrolizumab in this trial is for patients with recurrent prostate cancer, specifically those experiencing biochemical recurrence after radical prostatectomy. At the molecular level, pembrolizumab works by blocking the PD-1 pathway, which helps the immune system recognize and attack cancer cells more effectively. It is classified as an immune checkpoint inhibitor, a type of immunotherapy used to treat various cancers.

Investigated diseases

Recurrent Prostate Cancer – Recurrent prostate cancer refers to the return of cancer in the prostate gland after initial treatment, such as surgery or radiation, has been completed. This recurrence can be detected through rising levels of prostate-specific antigen (PSA) in the blood, even if there are no visible signs of cancer on imaging tests. The disease may progress slowly, and symptoms can vary, including difficulty urinating, pelvic pain, or bone pain if the cancer spreads. The progression of recurrent prostate cancer can be influenced by various factors, including the initial stage of the cancer and the type of treatment previously received. Monitoring PSA levels is crucial in managing the disease and determining the next steps in treatment.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-513633-20-00Protocol codeMK-3475-C51Estimated enrolment49 patientsSponsorMedical Center - University Of Freiburg

sourced from the EU Clinical Trials Register and site verification

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