Study on Olaparib Plus Abiraterone as First-line Therapy in Men With Metastatic Castration-resistant Prostate Cancer

The purpose of this study is to evaluate the efficacy and safety (including evaluating side effects) of combination of olaparib and abiraterone versus placebo and abiraterone in patients with metastatic castration-resistant prostate cancer (mCRPC) who have received no prior cytotoxic chemotherapy or new hormonal agents (NHAs) at metastatic castration-resistant prostate cancer (mCRPC) stage.

Inclusion Criteria: 1. Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form and in the study protocol. 2. Provision of signed and dated, written informed consent form prior to any mandatory study specific procedures, sampling, and analyses. 3. For inclusion in i) the optional exploratory genetic research and ii) the optional biomarker research, patients must fulfill the following criteria: * Provision of informed consent for genetic research prior to collection of sample. * Provision of informed consent for biomarker research prior to collection of sample. If a patient declines to participate in the optional exploratory genetic research or the optional biomarker research, there will be no penalty or loss of benefit to the patient. The patient will not be excluded from other aspects of the study. 4. Patients must be ≥18 years of age (or ≥19 years of age in South Korea) at the time of signing the informed consent form. For patients enrolled in Japan who are \