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Prostate CancerPhase 2NCT07005154

A Phase 2 Study to Evaluate the Effects of ASP5541 in Participants With Prostate Cancer

A Phase 2 study testing ASP5541, Prednisone and Prednisolone in people with Prostate Cancer and Metastatic Castration-Resistant Prostate Cancer, run by Astellas Pharma Global Development, Inc. at 54 sites in 12 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

Hormone therapy, or androgen deprivation therapy (ADT) is a standard way to treat prostate cancer. It works by reducing the amount of the main male sex hormone, testosterone in the body. Androgen receptor pathway inhibitors (ARPIs) are another type of hormone therapy. Read more about this study

Who is it for?
Ages 18 years and older, men only
What is being tested?
ASP5541, Prednisone and Prednisolone
Could I receive a placebo?
No, everyone receives an active treatment
How many people
218 participants
Where
54 sitesin 12 countries
Study dates
19 Aug 2025to 31 May 2032
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • Men only
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Participant is diagnosed with histologically or cytologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation or small cell features.
  • Participant has ECOG performance status of 0 or 1, or ECOG performance status of 2 if due to bone pain.
  • Participant must have an estimated life expectancy of ≥ 12 months with mHSPC or ≥ 6 months with mCRPC.
  • Participant is able to understand and comply with all study requirements and procedures.
  • Participant has been diagnosed with mCRPC or mHSPC documented by metastatic lesions on a bone scan, computed tomography (CT), magnetic resonance imaging (MRI) or prostate-specific membrane antigen positron emission tomography (PSMA-PET).
  • Participant is receiving ongoing ADT with a gonadotropin-releasing hormone (GnRH) analogue or has a history of bilateral orchiectomy (i.e., surgical or medical castration). Participant with mHSPC must have started castration therapy (medical or surgical) at least 14 days prior to Cycle 1 Day 1 (C1D1).
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  • Note: Participant who has not had a bilateral orchiectomy must have a plan to maintain effective GnRH analogue therapy for the duration of the study.
  • If the participant has mCRPC, participant has evidence of disease progression defined as 1 or more of the following criteria at study entry:
  • Evidence of radiographic progression of disease prior to first dose and following the most recent prostate cancer treatment, defined as progressive disease on CT/MRI per Response Evaluation Criteria in Solid Tumours (RECIST) v1.1 or on a bone scan per PCWG3.
  • PSA progression defined as an increase in PSA of at least 25% and ≥ 1 ng/mL above the nadir, confirmed by a second value 1 week later, and with at least 1 of the measurements within 90 days prior to screening. PSA nadir is defined as the lowest PSA during or after the most recent treatment.
  • If the participant has mCRPC, participant has a serum testosterone level < 1.73 nmol/L (< 50 ng/dL) at the Screening visit.
  • Male participant must agree to use contraception with female partner(s) of childbearing potential (including breastfeeding partner) throughout the treatment period and for 7 months after final ASP5541 administration.
  • Male participant must agree to remain abstinent or use a condom with pregnant partner(s) for the duration of the pregnancy throughout the investigational period and for 7 months after final ASP5541 administration.
  • Male participant must not donate sperm during the treatment period and for 7 months after final ASP5541 administration.
  • Participant agrees not to participate in another interventional study while receiving ASP5541 in the present study.
  • Participant should have normal serum potassium (within the local laboratory normal range) at screening without supplementation.

Who cannot join

  • Participant has any concurrent disease, infection or comorbid condition that interferes with the ability of the subject to participate in the study, which places the subject at undue risk or complicates the interpretation of data.
  • Participant has known active central nervous system (CNS) metastases. Note: Participant with CNS metastases who has been treated with surgery and/or radiation therapy, who is off pharmacologic doses of glucocorticoids and who is neurologically stable is eligible.
  • Participant has a known additional malignancy beyond prostate cancer that requires active treatment with the exception of any of the following:
  • Adequately treated basal cell carcinoma, squamous cell carcinoma of the skin, or in situ carcinoma of any type
  • Adequately treated Stage I cancer from which the participant is currently in remission and has been in remission for ≥ 2 years
  • Any other cancer from which the participant has been disease-free for ≥5 years
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  • Participant has clinically significant cardiac disease, defined as any of the following:
  • Clinically significant cardiac arrhythmias including bradyarrhythmia which are poorly controlled. Rate-controlled atrial fibrillation is permitted.
  • Congenital long QT syndrome.
  • QT interval corrected by Fridericia's formula (QTcF) ≥450 msec at Screening. If the QT interval corrected for heart rate intervals (QTc) is prolonged in a participant with a pacemaker or bundle branch block, the participant may be enrolled in the study if confirmed by the medical monitor.
  • History of clinically significant cardiac disease or congestive heart failure greater than New York Heart Association (NYHA) Class II or left ventricular ejection fraction measurement of < 50% at baseline.
  • Cohorts 1 and 3: Participant must not have unstable angina (symptoms at rest) or new-onset angina within the last 3 months or myocardial infarction within the past 6 months.
  • Cohort 2: Participants must not have symptomatic heart failure, unstable or new-onset angina or myocardial infarction within the past 12 months.
  • Cohorts 1 and 3: Uncontrolled hypertension, defined as systolic blood pressure > 160 mmHg or diastolic blood pressure > 100 mmHg that has been confirmed by 2 successive measurements despite optimal medical management.
  • Cohort 2: Uncontrolled hypertension, defined as systolic BP > 140 mmHg or diastolic BP > 90 mmHg that has been confirmed by 2 successive measurements despite optimal medical management. Participants may be receiving a maximum of 2 antihypertensives that were initiated at least 3 months prior to Cycle 1 Day 1.
  • Cohort 1 and 3: Arterial or venous thrombotic or embolic events such as cerebrovascular accident (including transient ischemic attacks), deep vein thrombosis, or pulmonary embolism within the 3 months before start of study medication (except for adequately treated catheter related venous thrombosis occurring > 1 month before Cycle 1 Day 1).
  • Cohort 2: Arterial thrombotic or embolic events such as cerebrovascular accident (including transient ischemic attacks) within the last 12 months.
  • Participant has any unresolved National Cancer Institute-Common Terminology Criteria for Adverse Events (NCI-CTCAE) (version 5.0) Grade > 2 toxicity at the Screening visit. Note: Participant receiving ongoing hormone replacement therapy for endocrine immune-related AEs without clinical symptoms will not be excluded.
  • Participant has had major surgery (e.g., requiring general anesthesia) within 30 days before screening, or has not fully recovered from surgery, or has major surgery planned during the time the participant is expected to participate in the study.
  • Participant has/had febrile illness or symptomatic, viral, bacterial (including upper respiratory infection) or fungal (noncutaneous) infection within 28 days prior to day 1.
  • Participant received a blood transfusion within 1 month of the first dose of study intervention.
  • Participant has a history of impaired pituitary or adrenal gland function (e.g., Addison's disease, Cushing's syndrome).
  • Participant has hemoglobin A1c (HbA1c) > 10% (if diabetes mellitus was previously diagnosed) or HbA1c > 8% (if diabetes mellitus was previously undiagnosed). (Excluded participant may be rescreened after referral and evidence of improved control of their condition.)
  • Participant has jaundice or known current active liver disease from any cause, including hepatitis A (hepatitis A virus IgM positive, but testing for hepatitis A in screening is not required), hepatitis B (hepatitis B virus surface antigen positive, confirmed by hepatitis B virus DNA), or hepatitis C (hepatitis C virus antibody positive, confirmed by hepatitis C virus RNA).
  • Participant has moderate or severe hepatic impairment (Child-Pugh Class B or C).
  • Participant has a known history of human immunodeficiency virus (HIV) infection (HIV antibody positive).
  • Participant has a body mass index > 40 kg/m2.
  • Participant has a history of drug or alcohol abuse according to Diagnostic and Statistical Manual of Mental Disorders, 5th edition criteria within 2 years before screening.
  • Participant received treatment with glucocorticoids greater than the equivalent of 10 mg per day of prednisone within 4 weeks prior to C1D1. The use of topical, intraocular, inhalational, intranasal or intra-articular glucocorticoids is permitted.
  • Participant received treatment with herbal medications with known anti-cancer properties or known effects on prostate physiology within 4 weeks prior to Cycle 1 Day 1 (e.g., saw palmetto, St. John's wort, turmeric/curcumin). Participants must agree not to use herbal products during study participation.
  • Participant is receiving current treatment with systemic ketoconazole, abiraterone acetate (AA) or any other cytochrome P450 17A1 (CYP17) inhibitor. Participant who has received systemic ketoconazole, AA or any other CYP17 inhibitor must have discontinued these agents ≥ 4 weeks prior to the first dose of study intervention.
  • Participant received prior systemic treatment with a strong inducer or inhibitor of cytochrome p450 3A4 (CYP3A4) within 4 weeks of first dose of study intervention. Concomitant use of strong inducers or inhibitors of CYP3A4 are not permitted on study.
  • Participant requires use of biotin (i.e., vitamin B7) or supplements containing biotin higher than the daily adequate intake of 30 μg. Note: Participant who switches from a high dose to a dose of 30 μg/day or less prior to first dose of study drug is eligible for study entry.
  • Participant is required to use any prohibited medication on the List of Excluded Concomitant Medications.
  • For mCRPC participants only: Participant has been treated with any of the following for prostate cancer, during the indicated time frame prior to enrollment:
  • Hormonal therapy (e.g., androgen receptor blockers [AR] antagonists, second-generation androgen receptor pathway inhibitors [including enzalutamide, apalutamide, darolutamide, rezvilutamide and AA], 5-alpha reductase inhibitors, estrogens, cyproterone acetate) within 4 weeks of C1D1. Note: Participant has been treated with bicalutamide within 6 weeks prior to enrollment is not permitted. Participant has been treated with all other GnRH analogues or antagonists is permitted.
  • Chemotherapy within 2 weeks or 5 half-lives of C1D1 (whichever is longer)
  • Biologic therapy within 4 weeks of C1D1
  • Immunotherapy within 4 weeks of C1D1
  • Radiation therapy (includes radioligands) within 4 weeks of C1D1
  • For mHSPC participants only: Participant has received any prior pharmacotherapy, radiation therapy or surgery for metastatic prostate cancer (the following exceptions are permitted):
  • Up to 4 months of ADT with GnRH agonists or antagonists or orchiectomy (within 3 months prior to C1D1) with or without concurrent antiandrogens.
  • Participant may have 1 course of palliative radiation or surgical therapy to treat symptoms resulting from metastatic disease if it was administered at least 4 weeks prior to C1D1.
  • Up to 6 cycles of docetaxel therapy, with the last dose of docetaxel ≤ 2 months prior to C1D1. A participant who has received docetaxel should have maintained a response to docetaxel of stable disease or better, by imaging and PSA, prior to C1D1.
  • Up to 6 months of ADT with GnRH agonists or antagonists or orchiectomy with or without concurrent antiandrogens prior to C1D1 if subject was treated with docetaxel, with no radiographic evidence of disease progression or rising PSA levels prior to C1D1.
  • Participant has received any investigational therapy within 4 weeks or 5 half-lives (whichever is longer) prior to C1D1.
  • Participant has received ASP5541 previously.
  • Participant has absolute neutrophil count < 1500/μL, platelet count < 100000/μL or hemoglobin < 9 g/dL (6.2 mmol/L) or international normalized ratio (INR) ≥ 1.5 (unless participant is taking oral anticoagulants in which case INR ≤ 2.0 is permitted) at Screening. Note: Participant may not have received any growth factors within 7 days or blood transfusions within 28 days prior to the hematology values obtained at Screening.
  • Participant has serum total bilirubin > 1.5 x upper limit of normal (ULN) (or > 3 x ULN for participants with documented Gilbert's disease), or serum alanine aminotransferase or aspartate aminotransferase > 2.5 x ULN at Screening.
  • Participant does not have adequate renal function defined as a calculated creatinine clearance < 30 mL/min as determined by a validated algorithm for calculating creatinine clearance.
  • Participant has serum albumin < 3.0 g/dL (30 g/L) at Screening.
  • Participant has a known or suspected hypersensitivity to ASP5541, prednisone, or any components of the formulations used.
  • Participant has a gastrointestinal disorder affecting absorption.

Trial locations and contacts

54 sites in 12 countries. Contact the study team or a site near you to ask about taking part.

Astellas Pharma Global Development, Inc. contact

800-888-7704

Astellas.registration@astellas.com

54 sites in 12 countries

United States12 sites, 12 recruiting

  • New Mexico Oncology Hematology Consultants

    Albuquerque, New Mexico, 87109

    Recruiting

  • University of Virginia Cancer Center

    Charlottesville, Virginia, 22908-07

    Recruiting

  • Associated Urological Specialists

    Chicago Ridge, Illinois, 60415

    Recruiting

  • Solaris Health - The Urology Group

    Cincinnati, Ohio, 45212

    Recruiting

  • NorthShore University HealthSystem

    Evanston, Illinois, 60201

    Recruiting

  • Clearview Cancer Institute

    Huntsville, Alabama, 35805

    Recruiting

  • UW Health Carbone Cancer Center

    Madison, Wisconsin, 53792

    Recruiting

  • Carolina Urologic Research Center

    Myrtle Beach, South Carolina, 29572

    Recruiting

  • Tennessee Oncology Nashville

    Nashville, Tennessee, 37203

    Recruiting

  • Ochsner Health - Ochsner Medical Center - New Orleans

    New Orleans, Louisiana, 70121

    Recruiting

  • Sharp HealthCare - Sharp Memorial Hospital

    San Diego, California, 92123

    Recruiting

  • H. Lee Moffitt Cancer Center

    Tampa, Florida, 33612

    Recruiting

Other trials in United States

Japan6 sites, 6 recruiting

  • Nippon Medical School Hospital

    Bunkyo-ku, Tokyo

    Recruiting

  • Harasanshin Hospital

    Fukuoka

    Recruiting

  • National Cancer Center Hospital East

    Kashiwa, Chiba

    Recruiting

  • The Cancer Institute Hospital of JFCR

    Koto, Tokyo

    Recruiting

  • Osaka International Cancer Institute

    Osaka

    Recruiting

  • Shizuoka Cancer Center

    Sunto-gun, Shizuoka

    Recruiting

Other trials in Japan

South Korea6 sites, 6 recruiting

  • Site KR82006

    Daegu

    Recruiting

  • Site KR82008

    Gwangju

    Recruiting

  • Site KR82002

    Seoul

    Recruiting

  • Site KR82003

    Seoul

    Recruiting

  • Site KR82004

    Seoul

    Recruiting

  • Site KR82007

    Seoul

    Recruiting

Other trials in South Korea

China5 sites, 5 recruiting

  • The First Affiliated Hospital, Zhejiang University School of Medicine

    Hangzhou, Zhejiang

    Recruiting

  • Huai'an First People's Hospital

    Huaian, 211731

    Recruiting

  • Renji Hospital Shanghai Jiaotong Univ School of Medicine

    Shanghai, 200127

    Recruiting

  • The Second Hospital of Tianjin Medical University

    Tianjin, Tianjin Municipality, 300211

    Recruiting

  • Subei People's Hospital

    Yangzhou, Jiangsu, 225001

    Recruiting

Other trials in China

France5 sites, 5 recruiting

  • Site FR33003

    Bordeaux

    Recruiting

  • Site FR33009

    Le Mans

    Recruiting

  • Site FR33008

    Lille

    Recruiting

  • Site FR33006

    Paris

    Recruiting

  • Site FR33004

    Strasbourg

    Recruiting

Other trials in France

Spain5 sites, 5 recruiting

  • Site ES34006

    Barcelona, Catalonia

    Recruiting

  • Site ES34005

    Barcelona

    Recruiting

  • Site ES34008

    Barcelona

    Recruiting

  • Site ES34001

    Madrid

    Recruiting

  • Site ES34003

    Santiago de Compostela

    Recruiting

Other trials in Spain

Italy4 sites, 4 recruiting

  • Site IT39004

    Milan

    Recruiting

  • Site IT39006

    Milan

    Recruiting

  • Site IT39005

    Roma

    Recruiting

  • Site IT39003

    Trento

    Recruiting

Other trials in Italy

Poland4 sites, 4 recruiting

  • Site PL48003

    Gdansk

    Recruiting

  • Site PL48007

    Gliwice

    Recruiting

  • Site PL48005

    Mysłowice

    Recruiting

  • Site PL48008

    Otwock

    Recruiting

Other trials in Poland

Taiwan3 sites, 3 recruiting

  • Site TW88603

    Kaohsiung City

    Recruiting

  • Site TW88604

    Taichung

    Recruiting

  • Site TW88602

    Taipei

    Recruiting

Other trials in Taiwan

Germany2 sites, 2 recruiting

  • Site DE49001

    Heinsberg

    Recruiting

  • Site DE49004

    Nürtingen, Baden-Wurttemberg

    Recruiting

Other trials in Germany

Puerto Rico1 site, 1 recruiting

  • PanOncology Trials

    San Juan

    Recruiting

Other trials in Puerto Rico

United Kingdom1 site, 1 recruiting

  • Site GB44003

    London

    Recruiting

Other trials in United Kingdom

About this study

Official title: A Phase 2, Open-label, Multi-cohort Study to Assess the Efficacy and Safety of ASP5541 in Participants With Advanced Prostate Cancer

Hormone therapy, or androgen deprivation therapy (ADT) is a standard way to treat prostate cancer. It works by reducing the amount of the main male sex hormone, testosterone in the body. Androgen receptor pathway inhibitors (ARPIs) are another type of hormone therapy. They either slow down how much testosterone is made or block testosterone from reaching the prostate cancer cells. Abiraterone acetate (AA) is an ARPI that is used to treat advanced prostate cancer. This type of treatment is usually given as a tablet with a steroid called prednisone/prednisolone to manage any medical problems from the hormone therapy.

ASP5541 is a different form of abiraterone acetate. It is given as an injection into the muscle. In this study, ASP5541 will be given to men with advanced prostate cancer, both with and without prednisone/prednisolone. This study will check the safety of ASP5541 and compare how well ASP5541 works in men with advanced prostate cancer compared to abiraterone acetate.

Read more

The main aims of the study are:

  • To check how well ASP5541 with prednisone/prednisolone works compared to AA with prednisone/prednisolone in men with advanced prostate cancer who haven't previously been treated with an ARPI.
  • To check the safety of ASP5541 given by itself in men with advanced prostate cancer that haven't previously been treated with an ARPI.
  • To check how well ASP5541 given by itself works compared to AA with prednisone/prednisolone in men with advanced prostate cancer that haven't previously been treated with an ARPI.
  • To check the safety of ASP5541 with prednisone/prednisolone in Japanese men with advanced prostate cancer.

Adult men with a certain type of advanced prostate cancer can take part. Their cancer has spread to other parts of the body (metastatic). The different types are:

  • Metastatic hormone-sensitive prostate cancer (mHSPC). Prostate cancer that needs testosterone to grow.
  • Metastatic castration-resistant prostate cancer (mCRPC). Prostate cancer that continues to grow even when testosterone levels are low.

In this study there will be 3 treatment groups:

  • In Group 1, men with mCRPC who haven't previously been treated with an androgen receptor pathway inhibitor will either be given ASP5541 and prednisone/prednisolone or be given abiraterone acetate and prednisone/prednisolone.
  • In Group 2, men with mHSPC who haven't previously been treated with an androgen receptor pathway inhibitor will either be given ASP5541 by itself or be given abiraterone acetate with prednisone/prednisolone.
  • In Group 3, Japanese men with mCRPC or mHSPC who may or may not have previously been treated with an androgen receptor pathway inhibitor will be given ASP5541 with prednisone/prednisolone.

ASP5541 will be given as an injection into a muscle every 12 weeks. Men with mCRPC will take prednisone/prednisolone twice daily and men with mHSPC will take prednisone/prednisolone once daily. Abiraterone acetate will be given as tablets to be taken once daily. All groups will also receive the standard of care treatment, such as androgen deprivation therapy.

The men in the study will visit their clinic regularly during and after treatment for health checks, including checking for any medical problems. Some men (Group 2) will check their blood pressure weekly at home. On some visits they will also have scans to check for any changes in their cancer. The number of visits and type of safety checks done at each visit will depend on the health of each person and when they completed their treatment.

Being tested
ASP5541, Prednisone, Prednisolone, abiraterone acetate, Adrenocorticotropic hormone
Keywords
ASP5541, PRL-02
Medical subject headings
Prostatic Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • ASP5541Drug

    Also called PRL-02

    Intramuscular Injection

  • PrednisoneDrug

    Oral

  • PrednisoloneDrug

    Oral

  • abiraterone acetateDrug

    Oral

  • Adrenocorticotropic hormoneDrug

    Intramuscular or intravenous injection

Study groups in NCT07005154
Study groupRoleWhat they receive
Cohort 1 (mCRPC) Group AExperimentalParticipants will receive ASP5541 every 12 weeks + prednisone/prednisolone twice daily
Receives: Drug: ASP5541; Drug: Prednisone; Drug: Prednisolone; Drug: Adrenocorticotropic hormone
Cohort 1 (mCRPC) Group BActive comparatorParticipants will receive abiraterone acetate once daily + prednisone/prednisolone twice daily
Receives: Drug: Prednisone; Drug: Prednisolone; Drug: abiraterone acetate; Drug: Adrenocorticotropic hormone
Cohort 2 (mHSPC) Group A (Safety Run In)ExperimentalParticipants will receive ASP5541 every 12 weeks
Receives: Drug: ASP5541; Drug: Adrenocorticotropic hormone
Cohort 2 (mHSPC) Group BExperimentalParticipants will receive ASP5541 every 12 weeks
Receives: Drug: ASP5541; Drug: Adrenocorticotropic hormone
Cohort 2 (mHSPC) Group CActive comparatorParticipants will receive abiraterone acetate once daily + prednisone/prednisolone once daily
Receives: Drug: Prednisone; Drug: Prednisolone; Drug: abiraterone acetate; Drug: Adrenocorticotropic hormone
Cohort 3 (mCRPC or mHSPC) Japanese Participants OnlyExperimentalParticipants will receive ASP5541 every 12 weeks + prednisone/prednisolone twice daily (for mCRPC) or prednisone/prednisolone once daily (for mHSPC)
Receives: Drug: ASP5541; Drug: Prednisone; Drug: Prednisolone; Drug: Adrenocorticotropic hormone

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Proportion of androgen receptor pathway inhibitor (ARPI) -naïve metastatic castration-resistant prostate cancer (mCRPC) participants with Prostate Specific Antigen (PSA) decline ≥ 90% (Cohort 1)

    PSA will be recorded from blood sample.

    Measured: Up to 37 months

  2. Rate of no mineralocorticoid toxicity (Cohort 2 Group A, Safety run-in)

    No mineralocorticoid toxicity is defined as experiencing neither Grade ≥ 1 hypokalemia nor Grade ≥ 2 hypertension.

    Measured: Up to 37 months

  3. Proportion of metastatic hormone-sensitive prostate cancer (mHSPC) participants with prostate-specific antigen (PSA) ≤ 0.2 ng/mL (Cohort 2)

    PSA will be recorded from blood sample.

    Measured: At 8 months

  4. Dose-limiting toxicities (DLTs) (Cohort 3)

    A DLT is defined as any event meeting the DLT criteria occurring during the first 28 days of treatment regardless of attribution to the study drug unless it is clearly related to disease progress or intercurrent illness.

    Measured: Up to Day 28

  5. Number of participants with Adverse Events (AEs) (Cohort 3)

    AEs will be coded using MedDRA. An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.

    Measured: Up to 39 months

  6. Number of Participants With Serious Adverse Events (SAEs) (Cohort 3)

    An SAE is defined as any untoward medical occurrence that, at any dose: Results in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is congenital anomaly/birth defect or other situations.

    Measured: Up to 39 months

  7. Number of participants with laboratory value abnormalities and/or AEs (Cohort 3)

    Number of participants with potentially clinically significant laboratory values.

    Measured: Up to 37 months

  8. Number of participants with electrocardiogram (ECG) abnormalities and/or AEs (Cohort 3)

    Number of participants with potentially clinically significant ECG values.

    Measured: Up to 36 months

  9. Number of participants with vital sign abnormalities and/or AEs (Cohort 3)

    Number of participants with potentially clinically significant vital sign values.

    Measured: Up to 37 months

  10. Number of participants with physical exam abnormalities and/or AEs (Cohort 3)

    Number of participants with potentially clinically significant physical exam values.

    Measured: Up to 36 months

  11. Eastern Cooperative Oncology Group (ECOG) Performance Status (Cohort 3)

    The ECOG scale will be used to assess performance status. Grades range from 0 (fully active) to 5 (dead). Negative change scores indicate an improvement. Positive scores indicate a decline in performance.

    Measured: Up to 36 months

Secondary outcomes (22)

  1. Radiographic progression-free survival (rPFS)

    Radiographic progression-free survival (rPFS) is defined as the time from the date of randomization/first dose date until the date of radiological progressive disease (PD) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) and Prostate Cancer Working Group 3 (PCWG3) as determined by investigator or death from any cause.

    Measured: Up to 84 months

  2. Prostate-specific antigen (PSA) decline ≥ 50% from baseline

    Proportion of participants who had a PSA decline of ≥ 50% from baseline, confirmed by a second consecutive PSA assessment at least 3 weeks later.

    Measured: Up to 37 months

  3. PSA decline ≥ 90% (Cohorts 2 & 3 only)

    Proportion of participants who had a PSA decline of ≥ 90% from baseline, confirmed by a second consecutive PSA assessment at least 3 weeks later.

    Measured: Up to 37 months

  4. PSA undetectable rate (≤ 0.2 ng/mL) (Cohorts 1 & 3)

    Proportion of participants achieving a PSA level ≤ 0.2 ng/mL at any time post baseline.

    Measured: Up to 37 months

  5. PSA undetectable rate (≤ 0.02 ng/mL)

    Proportion of participants achieving a PSA level ≤ 0.02 ng/mL at any time post baseline.

    Measured: Up to 37 months

  6. Time to PSA progression per PCWG3 criteria

    Time from first dose date to the date of the first PSA value demonstrating a ≥ 25% increase and an absolute increase of ≤ 0.2 ng/mL above the nadir (i.e., the lowest PSA value observed post baseline or at baseline), which is confirmed by a second consecutive value at least 3 weeks later.

    Measured: Up to 37 months

  7. Objective response rate (ORR)

    Proportion of participants who achieved a confirmed Complete Response (CR) or Partial Response (PR) in their soft tissue disease using RECIST v1.1 criteria and PCWG3 for bone disease.

    Measured: Up to 84 months

  8. Duration of response (DOR)

    Time from first date of confirmed CR or confirmed PR until the date of radiological PD per RECIST v1.1 and PCWG3 as determined by investigator or death from any cause.

    Measured: Up to 84 months

  9. Best overall response (BOR)

    The best response derived from all time points' overall responses (CR, PR, stable disease or non-CR/non-PD [for participants with no measurable disease at baseline], PD, not evaluable and not determined in order).

    Measured: Up to 84 months

  10. Number of participants with Adverse Events (AEs) (Cohorts 1 & 2)

    AEs will be coded using MedDRA. An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.

    Measured: Up to 39 months

  11. Number of Participants With Serious Adverse Events (SAEs) (Cohorts 1 & 2)

    An SAE is defined as any untoward medical occurrence that, at any dose: Results in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity is congenital anomaly/birth defect or other situations.

    Measured: Up to 39 months

  12. Number of participants with laboratory value abnormalities and/or AEs (Cohorts 1 & 2)

    Number of participants with potentially clinically significant laboratory values.

    Measured: Up to 37 months

  13. Urine potassium (Cohort 2)

    Potassium level will be recorded from urine sample.

    Measured: Up to 37 months

  14. Urine creatinine (Cohort 2)

    Creatinine level will be recorded from urine sample.

    Measured: Up to 37 months

  15. Number of participants with electrocardiogram (ECG) abnormalities and/or AEs (Cohorts 1 & 2)

    Number of participants with potentially clinically significant ECG values/cardiac monitoring.

    Measured: Up to 36 months

  16. Number of participants with vital sign abnormalities and/or AEs (Cohorts 1 & 2)

    Number of participants with potentially clinically significant vital sign values.

    Measured: Up to 37 months

  17. Number of participants with physical exam abnormalities and/or AEs (Cohorts 1 & 2)

    Number of participants with potentially clinically significant physical exam values.

    Measured: Up to 36 months

  18. ECOG Performance Status (Cohort 1 & 2 only)

    The ECOG scale will be used to assess performance status. Grades range from 0 (fully active) to 5 (dead). Negative change scores indicate an improvement. Positive scores indicate a decline in performance.

    Measured: Up to 36 months

  19. Number of participants with testosterone suppression to ≤ 1 ng/dL, or achieves a ≥ 90% reduction from baseline

    Testosterone value will be recorded from blood sample.

    Measured: Up to 37 months

  20. Mean testosterone value by timepoint

    Testosterone value will be recorded from blood sample.

    Measured: Up to 37 months

  21. Median time to testosterone suppression of levels ≤ 1 ng/dL

    Time to testosterone suppression is defined as time from date of randomization/first dose date until testosterone suppression to ≤ 1 ng/mL.

    Measured: Up to 37 months

  22. Time to pain progression

    Time to pain progression defined using pain scores from the Brief Pain Inventory - Short form (BPI-SF) and opiate analgesic use will be evaluated.

    Measured: Up to 36 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted5 Jun 2025
  2. Study start19 Aug 2025
  3. Primary completion31 May 2032 (estimated)
  4. Study completion31 May 2032 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
218 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07005154
Sponsor's protocol ID
5541-CL-0201
Other IDs
jRCT2031250142, CTR20255239, 2024-517653-27
Status last verified
Aug 2026
First submitted
27 May 2025
Last updated
3 Sep 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: Access to anonymized individual participant level data collected during the study, in addition to study-related supporting documentation, is planned for studies conducted with approved product indications and formulations, as well as compounds terminated during development. Studies conducted with product indications or formulations that remain active in development are assessed after study completion to determine if Individual Participant Data can be shared. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing ASP5541, Prednisone and Prednisolone in people with Prostate Cancer and Metastatic Castration-Resistant Prostate Cancer, run by Astellas Pharma Global Development, Inc. at 54 sites in 12 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 16 inclusion and 53 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 3 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 54 sites in United States, Japan, South Korea, China, France and 7 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Astellas Pharma Global Development, Inc. (800-888-7704, Astellas.registration@astellas.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Proportion of androgen receptor pathway inhibitor (ARPI) -naïve metastatic castration-resistant prostate cancer (mCRPC) participants with Prostate Specific Antigen (PSA) decline ≥ 90% (Cohort 1) (time frame: Up to 37 months). The study lists 11 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07005154.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Sep 2026.

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