An Efficacy and Safety Study of Niraparib in Men With Metastatic Castration-Resistant Prostate Cancer and DNA-Repair Anomalies

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.

ORR defined as percentage of participants with BRCA deoxyribonucleic acid (DNA)-repair anomalies and measurable disease whose best response is either CR or PR per RECIST 1.1 and with no evidence of bone progression per PCWG3 criteria.

CTC response rate was defined as the percentage of participants with CTC equals to (=) 0 per 7.5 milliliter (mL) blood at 8 weeks post-baseline in participants with baseline CTC greater than (>) 0.

OS is defined as time from enrollment to death from any cause.

rPFS was defined as time from enrollment to radiographic progression or death from any cause, whichever occurred first. Radiographic progression was evaluated per RECIST 1.1 criteria for soft tissue disease and per PCWG3 criteria for bone disease.

Time to radiographic progression is defined as time from enrollment to radiographic progression or death due to disease progression, whichever occurs first. Disease progression is defined as at least a 20 percent (%) increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that is the smallest on study). In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered progression.

Time to PSA progression was defined as time from enrollment to the first date of documented PSA progression based on PCWG3 criteria. A participant was considered to have a PSA progression if the PSA level had a 25 percent (%) or greater increase from nadir and an absolute increase of 2 nanograms per milliliter (ng/mL) or more, which is confirmed by a second value obtained in 3 or more weeks.

Time to SSE was defined as the time from enrollment to first occurrence of one of the following symptomatic skeletal events: tumor-related spinal cord compression, radiation to bone to relieve skeletal symptoms, surgery to bone or need for tumor-related orthopedic surgical intervention, symptomatic or pathologic fracture.

Duration of objective response is defined as time from CR or PR to radiographic progression of disease, unequivocal clinical progression or death, whichever occurs first. Unequivocal clinical progression defined as one or more of following: 1) deterioration in Eastern Cooperative Oncology Group Performance Status (ECOG PS) to Grade 3 or higher; 2) need to initiate any of following because of tumor progression (even in absence of radiographic evidence of disease): alternative anticancer therapy for prostate cancer, radiation therapy, surgical interventions for complications due to tumor progression.

An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/ biological agent under study.

Number of participants with worst toxicity grades for clinical laboratory tests (chemistry and hematology) based on NCI-CTCAE were reported. The chemistry laboratory parameters were: alanine aminotransferase (ALT) increased, alkaline phosphatase increased, aspartate aminotransferase (AST) increased, blood bilirubin increased, creatinine increased, gamma glutamyl transferase (GGT) increased and the hematology parameters were: hemoglobin increased, lymphocyte count increased. Grading was done as: Grade 1 (=mild), Grade 2 (=moderate), Grade 3 (=severe) and Grade 4 (=potentially life-threatening).