Clinical Study to Assess the Efficacy and Safety of Olaparib in Chinese Patients With Metastatic Castration-Resistant Prostate Cancer Who Have Failed Prior Treatment With a New Hormonal Agent and Have BRCA1/2 Mutations

rPFS is defined as the time from randomization until the date of objective disease progression (soft tissue or bone) or death (by any cause in the absence of progression) regardless of whether the patient withdraws from randomized therapy or receives another anti-cancer therapy prior to progression.

Time frame: Tumor assessments every 8 weeks (± 1 week) relative to the date of randomization until radiological progression as assessed by BICR or death (median duration of treatment of 9 and 6 months for Olaparib and Investigators Choice of NHA respectively).

Population: Full analysis set

Confirmed ORR is the percentage of patients with a Complete response (CR) or Partial response (PR), in their soft tissue disease per (RECIST v1.1), in the absence of progression on bone scan per Prostate Cancer Working Group 3 (PCWG3), confirmed \>=4 weeks later. Per RECIST v1.1, CR=Disappearance of all target lesions; PR = \>=30% decrease in the sum of diameters of target lesions. For each treatment group, confirmed ORR is the number of patients with a confirmed CR or PR divided by the number of patients in the treatment group.

Time frame: Tumor assessments every 8 weeks (± 1 week) from randomisation until radiographic progression assessed by BICR (median duration of treatment of 9 and 6 months for Olaparib and Investigators Choice of NHA respectively).

Population: Evaluable for response analysis set

OS is the time from the date of randomization until death due to any cause.

Time frame: From the time from the date of randomization until death due to any cause. Assessments continue up to 27 months after the first patient was randomized.

Population: Full analysis set

Proportion of participants achieving a ≥50% decrease in PSA from baseline to the lowest post-baseline PSA result, confirmed by a second consecutive PSA assessment at least 3 weeks later (PSA50 response)

Time frame: Blood samples for PSA assessment will be collected at baseline and every 4 weeks throughout the treatment phase, including at the study treatment discontinuation visit. Assessments continue up to 27 months post first patient enrolled.

Population: Full analysis set

Best percentage change from baseline in PSA is defined as the biggest reduction in PSA level compared with baseline (or the smallest increase in the absence of a reduction) taking account of all PSA values collected for each patient.

Time frame: Blood samples for PSA assessment will be collected at baseline and every 4 weeks throughout the treatment phase, including at the study treatment discontinuation visit. Assessments continue up to 27 months post first patient enrolled.

Population: Full Analysis Set (Only includes patients have baseline PSA and post-baseline PSA results for analysis of Best percentage change from baseline and includes patients have baseline PSA and week 12 PSA for analysis of Percentage change from baseline at Week 12 )

Time frame: Recorded from post discontinuation of study treatment up to primary data cut off date. Assessments continue up to 27 months post first patient enrolled.

Population: Full analysis set

Time from randomization to second progression by investigator assessment of radiological or clinical progression or death (PFS2)

Time frame: Tumor assessments will be performed every 8 weeks (±7 days) after randomization until radiologic progression or death, unless the participant withdraws consent. Assessments continue up to 27 months post first patient enrolled.

Population: Full analysis set

Time from first dose to the first symptomatic skeletal-related event

Time frame: Time from randomization to the first SSRE-radiation for skeletal symptoms, confirmed pathological fracture, confirmed spinal cord compression, or orthopaedic surgery for bone metastases. Assessments continue up to 27 months post first patient enrolled.

Population: Full analysis set

Time from randomization to opiate use for cancer-related pain

Time frame: Opioid use will be recorded at baseline and at every study visit, including the safety follow-up visit. Assessments continue up to 27 months post first patient enrolled.

Population: Full analysis set (Only includes patients who were not on opiates at baseline)