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Phase I/II Study of AZD6621 Safety and Efficacy in Adult Men with Metastatic 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 focuses on Metastatic Prostate Cancer, a form of prostate cancer that has spread to other parts of the body. The investigational drug being tested is AZD6621, a laboratory‑made protein designed to bring the body’s own immune cells (T cells) into contact with cancer cells by recognizing specific markers called STEAP2, CD3 and CD8. The drug is given by an intravenous infusion, which means it is delivered directly into a vein through a needle. The purpose of the study is to learn how safe the drug is, how well it works, and how it moves through the body over time.

Participants receive the drug in a stepwise manner, starting with low doses that are gradually increased to find a level that can be tolerated without serious side effects. Once a safe dose is identified, additional participants receive that dose to see whether the cancer shows signs of shrinking or slowing. Throughout the study, regular visits include physical examinations, blood tests that measure substances such as PSA (a protein that can indicate prostate cancer activity), and imaging scans that create pictures of the inside of the body. Any side effects, changes in laboratory results, or new symptoms are recorded, and the drug may be stopped if safety concerns arise.

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 assessments

    After enrollment, you will undergo baseline assessments that include medical history, physical examination, vital signs, electrocardiogram (ecg), and laboratory tests such as blood counts and chemistry panels.

    Baseline imaging studies will be performed to document the extent of metastatic prostate cancer, and a blood test for psa (prostate specific antigen) will be taken.

  2. Step 2

    Initial administration of <b>azd6621</b>

    The first dose of azd6621 will be given by intravenous infusion according to the schedule defined in the study protocol.

    The exact amount of the drug and the interval between doses will be determined by the dose escalation scheme, which starts with a low dose and may be increased in later cycles if safety criteria are met.

  3. Step 3

    Dose escalation monitoring

    During the dose escalation phase, you will be monitored for safety and for any dose limiting toxicities, which are side effects that prevent further dose increases.

    Monitoring includes regular laboratory tests, vital signs, ecg, and physical examinations, as well as reporting of any adverse events.

  4. Step 4

    Periodic efficacy assessments

    At predefined intervals, additional imaging studies and psa blood tests will be performed to evaluate the effect of the treatment on the cancer.

    These assessments help determine response rates and disease progression.

  5. Step 5

    Dose expansion (optimization)

    If the recommended dose for expansion is identified, you may continue receiving azd6621 at that dose as part of the expansion cohort.

    The same schedule of intravenous infusion, safety monitoring, laboratory testing, and efficacy assessments will be followed.

  6. Step 6

    Treatment discontinuation criteria

    Treatment may be stopped after a predetermined number of cycles, if unacceptable toxicity occurs, or if disease progression is observed on imaging or psa testing.

    The decision to discontinue is based on the safety and efficacy data collected during the trial.

  7. Step 7

    Post‑treatment follow‑up

    Following the last dose, you will attend follow‑up visits for continued safety monitoring, including laboratory tests and physical examinations.

    Long‑term follow‑up may include periodic imaging and psa measurements to assess overall survival and disease status.

Who can join the trial?

19 criteria

  • Be able to sign a written informed consent form and follow the study instructions.
  • Have a life expectancy longer than 12 weeks (about three months).
  • Show normal results on blood tests that check blood cells, kidney (renal), bone marrow, and liver function.
  • Weigh at least 35 kilograms (about 77 pounds).
  • Identify as male (assigned at birth), regardless of gender identity.
  • Use a reliable method of contraception (birth control) for yourself or your partner as required by the study.
  • Provide a signed and dated optional form for the Genomics Initiative before any genetic samples are taken.
  • Be at least 18 years old when you sign the consent form.
  • Have a confirmed diagnosis of metastatic prostate cancer that is proven by tissue testing.
  • Be medically or surgically castrated (very low testosterone), with blood testosterone ≤ 50 ng/dL, measured within 28 days before the first study dose. If you have not had surgery, you must be taking medication that lowers testosterone (called an LHRH agonist or antagonist) and be willing to continue it.
  • Have castration‑resistant prostate cancer, meaning the cancer keeps growing even though testosterone is low.
  • Have a blood level of PSA (prostate‑specific antigen) of at least 1 ng/mL at the screening visit.
  • Provide a recent or stored tissue sample (a tumor biopsy) from the prostate cancer.
  • Show that the cancer has gotten worse in the past 6 months, proven by at least one of the following:
    • Three rising PSA tests taken at least one week apart.
    • Growth of soft‑tissue tumors seen on imaging scans, using RECIST v1.1 criteria.
    • New bone lesions on a bone scan, using PCWG3 criteria (at least two new spots).
    • For Part A of the study, meet any previous cancer‑treatment rules in the protocol and, if in a special biopsy group, agree to have an extra tumor sample taken from a safe spot.
    • For Part B of the study, meet the prior treatment rules listed in the protocol for that part.
    • Have an ECOG performance status score of 0 or 1, meaning you are fully active or able to do light work.

Who cannot join the trial?

25 criteria

  • Any severe or uncontrolled disease that the doctor believes makes it unsafe for you to join the study.
  • If you have spinal cord compression (pressure on the spinal cord) that is not symptom‑free, already treated, stable, and does not require high‑dose steroids (more than 10 mg prednisone per day), you cannot participate.
  • Any problems with the central nervous system (CNS) (the brain or spinal cord) as listed in the study protocol.
  • Active or uncontrolled infection with hepatitis B or hepatitis C viruses (these are liver infections).
  • If you have a known HIV infection that is not well controlled, you are excluded.
  • Having had radiation therapy within 4 weeks before the first study drug dose (or local/focal radiation within 2 weeks).
  • Using systemic corticosteroids (anti‑inflammatory medicines like prednisone) at doses higher than 10 mg per day within 7 days before the first dose.
  • Having had a major surgical operation or a serious injury within 4 weeks before the first study dose.
  • Receiving any anti‑cancer therapy or being in another clinical trial within the last 21 days (or the drug’s 5 half‑lives, whichever is shorter), and having had CAR‑T cell therapy within the last 6 months.
  • Known allergy (hypersensitivity) to AZD6621 or any of its ingredients.
  • Being involved in planning or running the study (for example, as a study staff member).
  • Having any of the following heart‑related conditions:
    • Resting QT interval longer than 470 ms (a measure of heart electrical activity).
    • History of medication‑induced QT prolongation that required stopping the medication.
    • Congenital long QT syndrome, family history of long QT syndrome, or unexplained sudden death before age 40 in a close relative.
    • Poor heart pumping ability with an LVEF (left ventricular ejection fraction) less than 50 % on heart imaging.
    • If the doctor thinks you are unlikely to follow the study procedures, restrictions, and requirements.
    • Having received a live attenuated vaccine (a vaccine containing a weakened form of the germ) within 30 days before the first dose, or a COVID‑19 vaccine within 72 hours before the first dose.
    • If you have already enrolled in this study before.
    • Having certain cardiac arrhythmias (abnormal heart rhythms) that are symptomatic or need treatment, unless they are controlled by a pacemaker; this includes uncontrolled atrial fibrillation or sustained ventricular tachycardia.
    • History of another primary cancer, unless it was treated with curative intent, has had no active disease for at least 2 years, and is considered low risk for coming back.
    • History of, or planned, organ or allogeneic stem cell transplantation.
    • Unresolved side effects from previous cancer treatment that are moderate or severe (CTCAE Grade 2 or higher).
    • Past severe cytokine release syndrome (CRS) (Grade 3 or higher) or immune‑effector‑cell associated neurotoxicity syndrome (ICANS) (Grade 2 or higher) that must be fully resolved before screening.
    • Previous history of hemophagocytic lymphohistiocytosis / macrophage activation syndrome (a rare, severe immune reaction).
    • Active or prior autoimmune or inflammatory disorders within the last 3 years, or conditions that require permanent immune‑suppressing therapy.
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Investigated drugs

AZD6621 is an experimental medicine that helps the immune system target prostate cancer. It works by linking the body’s T‑cells, which are immune cells that can kill abnormal cells, to cancer cells that show a protein called STEAP2. The drug also attaches to CD3 and CD8 markers on T‑cells, bringing them close to the cancer cells so they can attack. In this trial, AZD6621 is given through an IV infusion to adults whose prostate cancer has spread. The study is looking at how safe the medicine is, how the body handles it, and whether it can reduce tumor size.

What is already known about the treatment

AZD6621 - This drug is supplied as a powder that is mixed with liquid and given by IV infusion. It is currently an investigational medicine being studied in early‑stage clinical trials and is not yet approved for general use. AZD6621 is being tested for treating metastatic prostate cancer. It works by a special antibody that attaches to a protein on prostate cancer cells (STEAP2) and to proteins on immune cells (CD3 and CD8), helping the immune cells find and attack the tumor. It is classified as a bispecific T‑cell‑engaging antibody, a type of immunotherapy.

Investigated diseases

Metastatic prostate cancer - A type of prostate cancer that has spread from the original gland to other parts of the body, commonly the bones or lymph nodes. The disease begins with abnormal cells in the prostate that grow uncontrollably. Over time, these cells break away and travel through the bloodstream or lymphatic system to distant sites. Once in new locations, they continue to multiply, forming new tumor deposits. The spread often leads to increasing numbers of affected areas as the condition advances.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase I/IITrial ID2025-520626-37-00Protocol codeD8020C00003Estimated enrolment171 patientsSponsorAstraZeneca AB

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