A Phase 2 Study to Evaluate the Effects of ASP5541 in Participants With Prostate Cancer
A Phase 2, Open-label, Multi-cohort Study to Assess the Efficacy and Safety of ASP5541 in Participants With Advanced Prostate Cancer
1 other identifier
interventional
218
10 countries
33
Brief 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. 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. 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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for phase_2 prostate-cancer
Started Jun 2025
Longer than P75 for phase_2 prostate-cancer
33 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
May 27, 2025
CompletedFirst Posted
Study publicly available on registry
June 5, 2025
CompletedStudy Start
First participant enrolled
June 19, 2025
CompletedPrimary Completion
Last participant's last visit for primary outcome
May 31, 2032
ExpectedStudy Completion
Last participant's last visit for all outcomes
May 31, 2032
May 1, 2026
April 1, 2026
7 years
May 27, 2025
April 30, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (11)
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.
Up to 37 months
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.
Up to 37 months
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.
At 8 months
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.
Up to Day 28
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.
Up to 39 months
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.
Up to 39 months
Number of participants with laboratory value abnormalities and/or AEs (Cohort 3)
Number of participants with potentially clinically significant laboratory values.
Up to 37 months
Number of participants with electrocardiogram (ECG) abnormalities and/or AEs (Cohort 3)
Number of participants with potentially clinically significant ECG values.
Up to 36 months
Number of participants with vital sign abnormalities and/or AEs (Cohort 3)
Number of participants with potentially clinically significant vital sign values.
Up to 37 months
Number of participants with physical exam abnormalities and/or AEs (Cohort 3)
Number of participants with potentially clinically significant physical exam values.
Up to 36 months
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.
Up to 36 months
Secondary Outcomes (22)
Radiographic progression-free survival (rPFS)
Up to 84 months
Prostate-specific antigen (PSA) decline ≥ 50% from baseline
Up to 37 months
PSA decline ≥ 90% (Cohorts 2 & 3 only)
Up to 37 months
PSA undetectable rate (≤ 0.2 ng/mL) (Cohorts 1 & 3)
Up to 37 months
PSA undetectable rate (≤ 0.02 ng/mL)
Up to 37 months
- +17 more secondary outcomes
Study Arms (6)
Cohort 1 (mCRPC) Group A
EXPERIMENTALParticipants will receive ASP5541 every 12 weeks + prednisone/prednisolone twice daily
Cohort 1 (mCRPC) Group B
ACTIVE COMPARATORParticipants will receive abiraterone acetate once daily + prednisone/prednisolone twice daily
Cohort 2 (mHSPC) Group A (Safety Run In)
EXPERIMENTALParticipants will receive ASP5541 every 12 weeks
Cohort 2 (mHSPC) Group B
EXPERIMENTALParticipants will receive ASP5541 every 12 weeks
Cohort 2 (mHSPC) Group C
ACTIVE COMPARATORParticipants will receive abiraterone acetate once daily + prednisone/prednisolone once daily
Cohort 3 (mCRPC or mHSPC) Japanese Participants Only
EXPERIMENTALParticipants will receive ASP5541 every 12 weeks + prednisone/prednisolone twice daily (for mCRPC) or prednisone/prednisolone once daily (for mHSPC)
Interventions
Intramuscular Injection
Oral
Oral
Intramuscular or intravenous injection
Eligibility Criteria
You may qualify if:
- 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).
- 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.
- +1 more criteria
You may not qualify if:
- 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
- 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.
- +38 more criteria
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (33)
Clearview Cancer Institute
Huntsville, Alabama, 35805, United States
H. Lee Moffitt Cancer Center
Tampa, Florida, 33612, United States
Associated Urological Specialists
Chicago Ridge, Illinois, 60415, United States
Ochsner Health - Ochsner Medical Center - New Orleans
New Orleans, Louisiana, 70121, United States
New Mexico Oncology Hematology Consultants
Albuquerque, New Mexico, 87109, United States
Solaris Health - The Urology Group
Cincinnati, Ohio, 45212, United States
Carolina Urologic Research Center
Myrtle Beach, South Carolina, 29572, United States
Tennessee Oncology Nashville
Nashville, Tennessee, 37203, United States
University of Virginia Cancer Center
Charlottesville, Virginia, 22908-07, United States
UW Health Carbone Cancer Center
Madison, Wisconsin, 53792, United States
Subei People's Hospital
Yangzhou, Jiangsu, 225001, China
The Second Hospital of Tianjin Medical University
Tianjin, Tianjin Municipality, 300211, China
Huai'an First People's Hospital
Huaian, 211731, China
Renji Hospital Shanghai Jiaotong Univ School of Medicine
Shanghai, 200127, China
Site FR33004
Strasbourg, France
Site DE49004
Nürtingen, Baden-Wurttemberg, Germany
Site DE49001
Heinsberg, Germany
National Cancer Center Hospital East
Kashiwa, Chiba, Japan
Shizuoka Cancer Center
Sunto-gun, Shizuoka, Japan
Nippon Medical School Hospital
Bunkyo-ku, Tokyo, Japan
The Cancer Institute Hospital of JFCR
Koto, Tokyo, Japan
Harasanshin Hospital
Fukuoka, Japan
Osaka International Cancer Institute
Osaka, Japan
PanOncology Trials
San Juan, Puerto Rico
Site KR82008
Gwangju, South Korea
Site KR82002
Seoul, South Korea
Site KR82003
Seoul, South Korea
Site KR82004
Seoul, South Korea
Site KR82007
Seoul, South Korea
Site ES34006
Barcelona, Catalonia, Spain
Site TW88603
Kaohsiung City, Taiwan
Site TW88602
Taipei, Taiwan
Site GB44003
London, United Kingdom
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Intervention Hierarchy (Ancestors)
Study Officials
- STUDY DIRECTOR
Medical Monitor
Astellas Pharma Global Development, Inc.
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 2
- Allocation
- RANDOMIZED
- Masking
- NONE
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
May 27, 2025
First Posted
June 5, 2025
Study Start
June 19, 2025
Primary Completion (Estimated)
May 31, 2032
Study Completion (Estimated)
May 31, 2032
Last Updated
May 1, 2026
Record last verified: 2026-04
Data Sharing
- IPD Sharing
- Will share
- Shared Documents
- STUDY PROTOCOL, SAP, CSR
- Time Frame
- Access to participant level data is offered to researchers after publication of the primary manuscript (if applicable) and is available as long as Astellas has legal authority to provide the data.
- Access Criteria
- Researchers must submit a proposal to conduct a scientifically relevant analysis of the study data. The research proposal is reviewed by an Independent Research Panel. If the proposal is approved, access to the study data is provided in a secure data sharing environment after receipt of a signed Data Sharing Agreement.
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/.