Niraparib

rPFS: time interval from date of randomization to first date of radiographic progression as assessed by investigator or death due to any cause, whichever occurred first. rPFS was determined by: (1) progression of soft tissue lesions measured by computerized tomography (CT) or magnetic resonance imaging (MRI) per response evaluation criteria in solid tumors (RECIST) 1.1; (2) progression of bone lesions observed by bone scan per prostate cancer working group 3 (PCWG3) criteria: bone progression was confirmed by subsequent scan greater than or equal to (\>=) 6 weeks later. Week 8 scan was baseline to which all subsequent scans were compared to determine progression. A confirmatory scan with \>=2 new lesions indicated progression; A confirmatory scan not showing \>=2 new lesions means no progression. If Week 8 scan shows \<2 new bone lesions compared to baseline, first scan with \>=2 new lesions compared to Week 8 scan indicated progression, when confirmed by a subsequent scan \>=6 weeks later.

rPFS: time interval from date of randomization to first date of radiographic progression as assessed by investigator or death due to any cause, whichever occurred first. rPFS was determined by: (1) progression of soft tissue lesions measured by CT or MRI per RECIST 1.1; (2) progression of bone lesions observed by bone scan per PCWG3 criteria: bone progression was confirmed by subsequent scan \>= 6 weeks later. Week 8 scan was baseline to which all subsequent scans were compared to determine progression. A confirmatory scan with \>=2 new lesions indicated progression; A confirmatory scan not showing \>=2 new lesions means no progression. If Week 8 scan shows \<2 new bone lesions compared to baseline, first scan with \>=2 new lesions compared to Week 8 scan indicated progression, when confirmed by a subsequent scan \>=6 weeks later.

rPFS: time interval from date of randomization to first date of radiographic progression as assessed by investigator or death due to any cause, whichever occurred first. rPFS was determined by: (1) progression of soft tissue lesions measured by CT or MRI per RECIST 1.1; (2) progression of bone lesions observed by bone scan per PCWG3 criteria: bone progression was confirmed by subsequent scan \>= 6 weeks later. Week 8 scan was baseline to which all subsequent scans were compared to determine progression. A confirmatory scan with \>=2 new lesions indicated progression; A confirmatory scan not showing \>=2 new lesions means no progression. If Week 8 scan shows \<2 new bone lesions compared to baseline, first scan with \>=2 new lesions compared to Week 8 scan indicated progression, when confirmed by a subsequent scan \>=6 weeks later.

As per BICR, rPFS is time interval from the date of randomization to radiographic progression or death, whichever occurred first. Radiographic progression was determined by: (1) progression of soft tissue lesions measured by computerized tomography (CT) or magnetic resonance imaging (MRI) as per response evaluation criteria in solid tumors (RECIST) 1.1; (2) Progression of bone lesions observed by bone scan based on prostate cancer working group 3 (PCWG3) criteria. PCWG3 criteria: bone progression was confirmed by subsequent scan greater than or equal to (\>=) 6 weeks later. Week 8 scan was baseline to which all subsequent scans were compared to determine progression. Confirmatory scan \>=2 new lesions indicate progression; scan does not show \>=2 new lesions means no progression. If Week 8 scan less than (\<) 2 new bone lesions compared to baseline, the initial scan \>=2 new lesions compared to Week 8 scan indicates progression if confirmed by subsequent scan \>=6 weeks later.

As per BICR, rPFS is time interval from the date of randomization to radiographic progression or death, whichever occurred first. Radiographic progression was determined by: (1) progression of soft tissue lesions measured by CT or MRI as per RECIST 1.1; (2) Progression of bone lesions observed by bone scan based on PCWG3 criteria. PCWG3 criteria: bone progression was confirmed by subsequent scan \>=6 weeks later. Week 8 scan was baseline to which all subsequent scans were compared to determine progression. Confirmatory scan \>=2 new lesions indicate progression; scan does not show \>=2 new lesions means no progression. If Week 8 scan \<2 new bone lesions compared to baseline, the initial scan \>=2 new lesions compared to Week 8 scan indicates progression if confirmed by subsequent scan \>=6 weeks later.

Number of participants with specified toxicity during Cycle 1 was reported. Only toxicities that occurred during safety evaluation period(defined as first 28 days of treatment-Cycle 1 of Part 1) was used for analysis of specified toxicities and for dose reduction decisions. Toxicities were graded for severity as per NCI-CTCAE, version 4.03. Safety evaluation criteria were: Any Grade(G) \>=3 non-hematological toxicity without anorexia, or constipation, fatigue improved to G\<=2 in \<7 days, vomiting and diarrhea resolved in \<=3 days, laboratory abnormalities with hospitalization, tumor flare improved to G\<=2 in \<=7 days, elevation in AST/ALT for \<=7 days and G3 hypertension controlled by medical therapy; any treatment-related(TR)G4 or G\>=3 thrombocytopenia required platelet transfusion; Any TR G4 neutropenia \>=7 days or G3 or 4 neutropenia with infection/fever \>38.5 degrees Celsius; Any TR SAE or intolerable toxicity.

ORR of soft tissue (visceral or nodal disease) was defined as percentage of participants with measurable disease who achieved a best response of either complete response (CR) or partial response (PR) as assessed by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 with no evidence of bone progression according to prostate cancer working group 3 (PCWG3) criteria.

Composite response rate was defined as the percentage of participants who had a composite response which is defined as one of the following PCWG3 criteria: Objective response (percentage of participants with measurable disease who achieved a best response of either CR or PR as assessed by RECIST 1.1 with no evidence of bone progression according to PCWG3 criteria) (confirmed per RECIST 1.1), or; circulating tumor cells (CTC) response: defined as CTC=0 per 7.5 milliliters (mL) of blood at 8 weeks for participants who had CTC greater than or equal to (\>=) 1 at baseline or CTC less than (\<) 5 per 7.5 mL with CTC \>=5 at baseline, confirmed by a second consecutive value obtained 4 or more weeks later, or prostate-specific antigen (PSA) declined of \>=50 percentage (%), measured twice 3 to 4 weeks apart. This outcome measure was analyzed for specified arms only as pre-planned in the protocol.

AE was defined as an any untoward medical occurrence in a clinical study subject administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the treatment.

AE was defined as an any untoward medical occurrence in a clinical study subject administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the treatment.

AE was defined as an any untoward medical occurrence in a clinical study subject administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the treatment. An assessment of severity grade was made using the National Cancer Institute - Common Terminology Criteria for Adverse Events (NCI-CTCAE) as Grade 1 (mild): awareness of symptoms that are easily tolerated, causing minimal discomfort and not interfering with everyday activities; Grade 2 (moderate): sufficient discomfort is present to cause interference with normal activity; Grade 3 (severe): extreme distress, causing significant impairment of functioning or incapacitation, prevents normal everyday activities; Grade 4 (Life-threatening): urgent intervention indicated; and Grade 5 (death).

AE was defined as an any untoward medical occurrence in a clinical study subject administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the treatment. An assessment of severity grade was made using the NCI-CTCAE as Grade 1 (mild): awareness of symptoms that are easily tolerated, causing minimal discomfort and not interfering with everyday activities; Grade 2 (moderate): sufficient discomfort is present to cause interference with normal activity; Grade 3 (severe): extreme distress, causing significant impairment of functioning or incapacitation, prevents normal everyday activities; Grade 4 (Life-threatening): urgent intervention indicated; and Grade 5 (death).

Cmax is defined as maximum observed plasma concentration of niraparib and abiraterone acetate (AA) after a single dose.

Cmax/dose of niraparib was defined as maximum observed plasma concentration of niraparib Cmax normalized by the dose of niraparib administered with AA after a single dose.

AUC(0-168 hours) was defined as area under the plasma concentration-time curve from time zero to 168 hours of Niraparib administered with AA After a single dose.

AUC0(168 hours)/dose was defined as area under the plasma concentration-time curve for niraparib from time 0 to 168 hours of niraparib administered with AA after a single dose.

ORR defined as percentage of participants with BRCA DNA-repair anomalies and measurable disease whose best response is either complete response (CR) or partial response (PR) per Response Evaluation Criteria in Solid Tumors (RECIST 1.1) and with no evidence of bone progression per Prostate Cancer Working Group 3 (PCWG3) criteria.

Cmax,ss is defined as maximum observed analyte concentration at steady state.

AUC (0-24h),ss is defined as area under the plasma concentration-time curve from time zero to 24 hours at steady state.

Ratio of individual Cmax,ss values between test and reference treatment will be assessed.

Ratio of individual AUC (0-24h),ss values between test and reference treatment will be assessed.

RP2D will be defined as the highest dose of study drug at which less than 33 percent (%) of participants experience dose limiting toxicity (DLT).

Number of participants will be assessed to further explore safety and antitumor activity in Part 2 (dose expansion) of study.