A Study to Evaluate the Safety and Drug Levels of ASP5541 in Chinese Participants With Prostate Cancer

NCT07339267 | Recruiting Phase 1 FDA Drug

• 1 other identifier: 5541-CL-0102
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

Brief Summary

In this study, ASP5541 will be given to Chinese men with prostate cancer. It will be given together with prednisone and androgen deprivation therapy (ADT). Prednisone is a steroid, and ADT is already given to the men as their standard of care for prostate cancer. The main aims of the study are to check the safety of ASP5541, when given with prednisone and ADT, and to check how ASP5541 moves through the bodies of Chinese men. The men will receive ASP5541 as an injection into a muscle (intramuscular injection) at the side of the hip. They will all receive the same dose of ASP5541. The men will be given prednisone and ADT according to their label. The men will continue to receive ASP5541 with prednisone and ADT until their cancer gets worse or the doctor decides the men should stop study treatment.

Conditions

Prostate Cancer; Metastatic Castration-Resistant Prostate Cancer; Metastatic Hormone Sensitive Prostate Cancer

Keywords

ASP5541; PRL-02; Pharmacokinetics

Outcome Measures

Primary Outcomes (14)

• Pharmacokinetics (PK) of Abiraterone Decanoate in Plasma: Maximum Concentration (Cmax)

  Cmax will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone Decanoate in Plasma: Time to Maximum Concentration (Tmax)

  Tmax will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone Decanoate in Plasma: Area Under the Curve from Time 0 to the Time of the Last Measurable Concentration (AUClast)

  AUClast will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone Decanoate in Plasma: Area Under the Concentration Time Curve from the Time of Dose Extrapolated to Time Infinity (AUCinf)

  AUCinf will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone in Plasma: Maximum Concentration (Cmax)

  Cmax will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone in Plasma: Time to Maximum Concentration (Tmax)

  Tmax will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone in Plasma: Area Under the Curve from Time 0 to the Time of the Last Measurable Concentration (AUClast)

  AUClast will be recorded from the PK plasma samples collected.

  Up to 6 months

• PK of Abiraterone in Plasma: Area Under the Concentration Time Curve from the Time of Dose Extrapolated to Time Infinity (AUCinf)

  AUCinf will be recorded from the PK plasma samples collected.

  Up to 6 months

• Number of Participants with Adverse Events (AEs)

  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. Note: An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of study intervention. This includes events related to the comparator, if applicable, and events related to the (study) procedures.

  Up to 33 months

• Number of Participants with Laboratory Value Abnormalities and/or AEs

  Number of participants with potentially clinically significant laboratory values.

  Up to 31 months

• Number of Participants with Electrocardiogram (ECG) Abnormalities and/or AEs

  Number of participants with potentially clinically significant ECG values.

  Up to 31 months

• Number of Participants with Vital Sign Abnormalities and/or AEs

  Number of participants with potentially clinically significant vital sign values.

  Up to 31 months

• Number of Participants with Physical Exam Abnormalities and/or AEs

  Number of participants with potentially clinically significant physical exam values.

  Up to 31 months

• Number of Participants at Each Grade of Eastern Cooperative Oncology Group (ECOG) Performance Status Score

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

  Up to 31 months

Secondary Outcomes (9)

• Number of mHSPC Participants with Prostate-specific Antigen (PSA) ≤ 0.2 ng/mL Levels at 8 Months

  Month 8

• Number of mHSPC Participants with Prostate-specific Antigen (PSA) ≤ 0.2 ng/mL Levels at 12 Months

  Month 12

• Number of Participants with a PSA decline ≥ 30% from Baseline

  Up to 24 months

• Number of Participants with a PSA decline ≥ 50% from Baseline

  Up to 24 months

• Number of Participants with a PSA decline ≥ 90% from Baseline

  Up to 24 months

Study Arms (1)

ASP5541

EXPERIMENTAL

Participants will receive ASP5541 once every 12 weeks and prednisone either once daily (mHSPC) or twice daily (mCRPC).

Drug: ASP5541; Drug: Prednisone

Interventions

ASP5541 DRUG

Intramuscular injection

Also known as: PRL-02

ASP5541

Prednisone DRUG

Oral

ASP5541

Eligibility Criteria

• Age: 18 Years - 85 Years
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

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 Eastern Cooperative Oncology Group (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 metastatic hormone-sensitive prostate cancer (mHSPC) or ≥ 6 months with metastatic castration-resistant prostate cancer (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 androgen deprivation therapy (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 has adequate ventrogluteal muscle mass for an intramuscular injection.

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. 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.
• 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.
• 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 the start of study medication).
• 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 90 days before screening, or will not have fully recovered from surgery, or has major surgery planned during the time the participant is expected to participate in the study.

Sponsors & Collaborators

• Astellas Pharma Global Development, Inc.: lead

Study Sites (1)

Beijing Hospital

Beijing, Beijing Municipality, China

RECRUITING

MeSH Terms

Conditions

Prostatic Neoplasms

Interventions

Prednisone

Condition Hierarchy (Ancestors)

Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Genital Diseases; Urogenital Diseases; Prostatic Diseases; Male Urogenital Diseases

Intervention Hierarchy (Ancestors)

Pregnadienediols; Pregnadienes; Pregnanes; Steroids; Fused-Ring Compounds; Polycyclic Compounds

Study Officials

• Medical Lead

  Astellas (China) Investment Co., Ltd.

  STUDY DIRECTOR

Central Study Contacts

Astellas Pharma Global Development, Inc.

CONTACT

800-888-7704; Astellas.registration@astellas.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 5, 2026
• First Posted: January 14, 2026
• Study Start: January 20, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028
• Last Updated: February 18, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)