The purpose of this study is to evaluate the efficacy and safety of Olaparib compared with standard of care (Enzalutamide or Abiraterone Acetate) in Chinese men with metastatic castration-resistant prostate cancer who have failed prior treatment with a new hormonal agent and have BRCA1/2 mutations.

This is a Phase IV, randomized, open-label, 2-arm, multicenter study evaluating the efficacy and safety of olaparib in Chinese men with metastatic castration-resistant prostate cancer (mCRPC) who have failed prior treatment with a new hormonal agent (NHA) and have BRCA1/2 mutations. Approximately 42 subjects will be randomized in a 2:1 ratio to olaparib or to investigator's choice of NHA (enzalutamide or abiraterone acetate).

Inclusion criteria：

1. Histologically confirmed diagnosis of prostate cancer.
2. Documented evidence of metastatic castration resistant prostate cancer (mCRPC).
3. Subjects must have progressed on prior new hormonal agent (e.g. abiraterone acetate and/or enzalutamide) for the treatment of metastatic prostate cancer and/or CRPC .
4. Ongoing therapy with LHRH analog or bilateral orchiectomy.
5. Radiological progression at study entry while on androgen deprivation therapy (or after bilateral orchiectomy).
6. Deleterious or suspected deleterious BRCA1/2 mutation in tumor tissue.
7. Normal organ and bone marrow function measured within 28 days prior to administration of study treatment.
8. Eastern Cooperative Oncology Group (ECOG) performance status 0-2 with no deterioration over the previous 2 weeks prior to baseline or day of first dosing.

Exclusion criteria：

1. Any previous treatment with a poly (adenosine diphosphate [ADP] ribose) polymerase (PARP) inhibitor, including olaparib.
2. Subjects who had any previous treatment with DNA-damaging cytotoxic chemotherapy, except if for non-prostate cancer indication and last dose > 5 years prior to randomization.
3. History of another primary malignancy except for malignancy treated with curative intent with no known active disease for ≥5 years before the first dose of study intervention and of low potential risk for recurrence.
4. Spinal cord compression or brain metastases unless asymptomatic, stable, and not requiring steroids for at least 4 weeks prior to start of study intervention.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All requests will be evaluated as per the AZ disclosure commitment（https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure).

"Yes" indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please refer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved, AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool . Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access.For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.