Phase 2 Study on the Effects of ASP5541 in Men with Advanced Prostate Cancer

Inclusion Criteria

• Diagnosed with prostate cancer that has spread to other parts of the body and does not have certain rare features.
• In good general health, with a performance status that allows for daily activities.
• Life expectancy of at least 12 months for hormone-sensitive cancer or 6 months for castration-resistant cancer.
• Able to understand and follow study procedures, including filling out questionnaires.
• Agree to use contraception during the study and for a period after the study ends.
• Have enough muscle mass for an injection.
• Willing to not participate in other studies while in this one.
• Normal potassium levels in the blood.

Additional Criteria for Group 1:

• Diagnosed with castration-resistant prostate cancer with evidence of disease progression.
• Receiving ongoing hormone therapy or have had surgical castration.
• Low testosterone levels at screening.
• Able to swallow the standard treatment tablet.

Additional Criteria for Group 2:

• Diagnosed with hormone-sensitive prostate cancer.
• Started hormone therapy at least 14 days before the study.
• Able to swallow the standard treatment tablet.
• Have accessible tumor tissue for analysis.

Exclusion Criteria

• Have other serious health conditions that could interfere with the study.
• Have active cancer spread to the brain unless treated and stable.
• Have another active cancer requiring treatment, except for certain skin cancers or early-stage cancers in remission.
• Have unresolved severe side effects from previous treatments.
• Have had major surgery recently or plan to have surgery during the study.
• Have recent infections or fever.
• Have received a blood transfusion recently.
• Have certain glandular disorders or uncontrolled diabetes.
• Have active liver disease or certain viral infections.
• Have a history of drug or alcohol abuse.
• Have received certain medications or treatments recently that are not allowed in the study.
• Have a known allergy to the study drugs.
• Have a gastrointestinal disorder affecting absorption.

Additional Exclusions for Group 1:

• Have had certain advanced prostate cancer treatments recently.
• Have a known BRCA mutation unless treated with specific drugs.
• Have significant heart disease or uncontrolled high blood pressure.

Additional Exclusions for Group 2:

• Have had certain advanced prostate cancer treatments recently.
• Have significant heart disease or uncontrolled high blood pressure.
• Have had recent blood clots or strokes.