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.
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 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.
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