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Phase 1/2 First‑in‑Human Study of Oral GSK5471713B in Adults with Metastatic Castration‑Resistant Prostate Cancer

Verified siteInvestigationalNo placebo
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What is this trial about?

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

The study involves adults with metastatic castration‑resistant prostate cancer, a form of prostate cancer that has spread beyond the prostate and no longer reacts to hormone therapy that normally slows its growth. The investigational medicine being tested is an oral tablet called GSK5471713, which is taken by mouth.

The purpose is to evaluate the safety and tolerability of the study drug and to select appropriate dose levels for further testing. Participants will receive the medication at gradually increasing amounts (dose escalation) while undergoing regular check‑ups, blood tests, and imaging to monitor for side effects and any changes in the disease. Researchers will also track changes in the blood marker prostate‑specific antigen, which can indicate whether the cancer is responding. The study lasts several months, with scheduled visits, and participants may stop the medication if serious problems occur.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessment

    baseline assessment is performed after joining the study. you will provide your medical history, undergo blood tests, and may have imaging studies to document the status of your prostate cancer.

  2. Step 2

    Start study medication

    You will receive gsk5471713, an oral film‑coated tablet. the tablet is taken by mouth as directed by the study team. the exact dose, frequency, and length of treatment are defined in the study protocol and will be explained to you by the clinical staff.

  3. Step 3

    Regular safety visits

    You will attend scheduled clinic visits for safety monitoring. during these visits blood samples are taken to check how the medication is affecting your body and to look for any side effects.

  4. Step 4

    Dose escalation phase

    If the initial dose is well tolerated, the study may increase the dose in a stepwise manner. each new dose level is given only after the study team confirms that the previous dose did not cause serious side effects.

  5. Step 5

    Dose optimization phase

    After the escalation phase, the dose may be adjusted to find the amount that provides the best balance between effectiveness and safety. this adjustment is made according to the observations from your safety visits.

  6. Step 6

    Ongoing treatment

    You will continue taking the medication for the period specified in the protocol, which is determined by the study design. the exact duration will be communicated to you when you start treatment.

  7. Step 7

    Final evaluation

    At the end of the study period a final evaluation is performed. this includes repeat blood tests, imaging, and assessment of any side effects that occurred during the trial.

Who can join the trial?

7 criteria

  • Be a man who is at least 18 years old.
  • Have metastatic castration resistant prostate cancer (mCRPC), which means the cancer has spread and keeps growing even when the body’s testosterone is very low; this must be confirmed by a tissue test (a lab look at cells from the prostate) showing adenocarcinoma.
  • Experience cancer growth while receiving androgen deprivation therapy (ADT) (treatment that lowers testosterone) or after having a bilateral orchiectomy (surgical removal of both testicles).
  • Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, indicating they are fully active or able to carry out light work.
  • Show disease progression while on ADT and have taken at least one prior androgen receptor pathway inhibitor (ARPI) for hormone‑sensitive or castration‑resistant prostate cancer, and have received 1‑2 previous courses of taxane‑based chemotherapy (a type of cancer‑killing drug).
  • Have a blood testosterone level lower than 50 ng/dL during screening, and must have had a bilateral orchiectomy or be on continuous ADT for at least 4 weeks before the first study dose, continuing ADT throughout the trial.
  • Have adequate organ function, meaning the kidneys, liver, and other vital organs are working well enough for the study.

Who cannot join the trial?

18 criteria

  • Having a prostate cancer type called small cell neuroendocrine carcinoma or any cancer that is not an adenocarcinoma.
  • Having ever received an organ transplant.
  • Taking medicines that can lengthen the heart’s QT interval (a measure of electrical activity) or cause a dangerous rhythm called torsade de pointes.
  • Being allergic to any part of the study drug, its inactive ingredients (excipients), or having had severe drug allergies or strong reactions after previous treatments.
  • Having had a PSMA‑targeted radioactive therapy within 2 months before the first study dose.
  • Having received any other cancer treatment within 4 weeks before the first study dose.
  • Having previously used a therapy that breaks down the androgen receptor (AR Degrader).
  • Having abnormal adrenal gland function now or in the past, or taking medicines that affect the adrenal glands.
  • Having a serious liver problem now or a history of liver disease, infection, or abnormal liver test results.
  • Having any active kidney (renal) disease.
  • Having untreated brain or central nervous system (CNS) cancer spread, or brain/CNS cancer that has gotten worse.
  • Having significant problems with the digestive system (gastrointestinal abnormalities).
  • Having weakened heart function or any serious heart disease.
  • Having had major surgery within 4 weeks before the first study dose.
  • Having been diagnosed with or having a history of another invasive cancer in the past 5 years, except for the prostate cancer being studied.
  • Having a serious infection within 4 weeks before the first study dose.
  • Having ongoing side effects from previous treatment that have not improved to a mild level (grade 1) or back to normal.
  • Having an active or significant long‑term lung disease (chronic respiratory disease).
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Investigated drugs

GSK5471713 is an experimental oral tablet being studied for the first time in humans. It is given to adults with metastatic castration‑resistant prostate cancer to see if it is safe and how well it is tolerated. The trial will increase the amount given step by step to find the best doses for later testing.

What is already known about the treatment

GSK5471713B - This investigational drug is taken by mouth as a film‑coated tablet. It is currently in a Phase 1/2 first‑time‑in‑human study and is not yet approved for any medical use. The medication is being tested for treating metastatic castration‑resistant prostate cancer, a type of advanced prostate tumor. It works as an experimental small‑molecule inhibitor that blocks a specific protein that helps cancer cells grow and survive, placing it in the class of oral targeted cancer therapies.

Investigated diseases

Prostate cancer - Prostate cancer is a growth of abnormal cells that starts in the prostate gland, a small organ that makes fluid for semen. In the early stage, the tumor may be small and cause no symptoms. Over time it can grow larger and may spread to nearby tissues such as the bladder or rectum. The cancer can also travel through the bloodstream or lymph system to distant parts of the body, most commonly the bones. As it advances, the disease may affect urinary function and cause discomfort.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase I/IITrial ID2025-523874-17-00Protocol code300164Estimated enrolment54 patientsSponsorGlaxosmithkline Research & Development Limited

sourced from the EU Clinical Trials Register and site verification

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