IRF assessed PFS was defined as time (in months) from randomization until the date of first documented radiologic progressive disease per response evaluation criteria in solid tumors (RECIST) version 1.1 or death from any cause, whichever occurs first. As per RECIST v1.1, progression defined as 1) for target lesions: at least a 20% increase in the sum of target lesion measurements, compared to the smallest sum on study (including baseline), the absolute increase in the sum has to be at least 5 millimeter (mm); 2) for non-target lesions: unequivocal progression of non-target lesions, evaluated as a whole, such that it is clear that treatment has failed and disease is progressing, regardless of the status of the target lesions; 3) and/or appearance of one or more new lesions. The analysis was performed by Kaplan-Meier method.

Intent-to-treat (ITT) analysis population included all randomized participants.

Investigator assessed objective response was defined as the percentage of participants with a partial response (PR) or complete response (CR) as defined by RECIST v1.1. For target lesions: 1) CR: disappearance of all non-nodal target lesions. Target lymph nodes must reduce to less than 10 mm in short axis. 2) PR: At least a 30% decrease in the sum of diameters of target lesions, compared to the sum at baseline. For non-target lesions, CR: disappearance of all non-target lesions. Percentage of participants with objective response reported are based upon unconfirmed CR/PR.

ITT with measurable disease analysis population included all participants in the ITT population who had at least 1 target lesion identified at baseline.

OS was defined as the time (in months) from randomization to death due to any cause. If death was not observed at the time of study cut-off date or permanently lost to follow-up, OS was censored at the date the participant was last known to be alive on or before the study cut-off date, whichever was earlier. The analysis was performed by Kaplan-Meier method.

ITT analysis population included all randomized participants.

A predose PK sample was considered dose-compliant based on the following criteria: A participant must have received 21 consecutive days of 1 mg talazoparib without dosing interruption prior to sample collection; and the predose PK sample must have been collected 24 hours +/- 10 percent (2 hours and 24 minutes) after the previous day's dose and no more than 5 minutes (0.083 hours) after the administration of the dose on the day of PK sample collection.

Analysis population included participants who received at least 1 dose of talazoparib and had dose compliant pharmacokinetic (PK) predose sample. Here, "number analyzed" signifies number of participants who were evaluable for the specified categories. This endpoint was not planned to be analyzed for the reporting arm "Physician's Choice Treatment".

An adverse events (AE) was any untoward medical occurrence (e.g., sign, symptom, illness, disease or injury) in a participant administered study drug or other protocol-imposed intervention, regardless of attribution. SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent are events between first dose of study drug or the day before initiation of a new antineoplastic therapy or 30 days after the date of the last dose date of study drug, whichever occurred first, that were absent before treatment or that worsened relative to pretreatment state. AEs included both SAEs and all non-SAEs.

Safety analysis population included all participants who received at least 1 dose of any study drug (talazoparib or protocol-specified PCT).

Toxicity grades were evaluated based on as National Cancer Institute Common Toxicity Criteria for Adverse Events Version 4.03 (NCI CTCAE v4.03). NCI CTCAE v4.03 defined the severity grade as: grade 1 (mild), grade 2 (moderate), grade 3 (severe), grade 4 (potentially life threatening) and grade 5 (death related to AE) for each parameter. Key hematology parameters included hemoglobin (gram per liter [g/L]), leukocytes (10^6 cells per liter), lymphocytes (10^6 cells per liter), neutrophils (10^6 cells per liter), and platelets (10^9 cells per liter). Low value indicated lower values than the baseline values and high value indicated higher values than the baseline values. Only those categories in which at least 1 participant had data were reported.

Safety analysis population included all participants who received at least 1 dose of any study drug (talazoparib or protocol-specified PCT).

Toxicity grades were evaluated based on as NCI CTCAE v4.03. NCI CTCAE v4.03 defined the severity grade as: grade 1 (mild), grade 2 (moderate), grade 3 (severe) and grade 4 (potentially life threatening) and grade 5 (death related to AE) for each parameter. Key chemistry parameters included alanine aminotransferase (units per liter), alkaline phosphatase (units per liter), aspartate aminotransferase (units per liter) and bilirubin (micromole per liter). High value indicated higher values than the baseline values and low value indicated lower values than the baseline values. Only those categories in which at least 1 participant had data were reported.

Safety analysis population included all participants who received at least 1 dose of any study drug (talazoparib or protocol-specified PCT).

Criteria for potentially clinically significant changes in vital signs included a) Systolic blood pressure: 1) absolute results (AB) greater than (>) 180 millimeter of mercury (mmHg) and increase from baseline (IFB) greater than or equal to (>=) 40 mmHg, 2) absolute results less than (<) 90 mmHg and decrease from baseline (DFB) >30 mmHg; b) Diastolic blood pressure: 1) absolute results >110 mmHg and >=30 mmHg increase from baseline, 2) absolute results <50 mmHg and >20 mmHg decrease from baseline 3) >=20 mmHg increase from baseline; c) Heart rate: 1) absolute results>120 beats per minute [bpm] and >30 bpm increase from baseline, 2) absolute results <50 bpm and >20 bpm decrease from baseline and d) Weight: >10 percent [%] decrease from baseline.

Safety analysis population included all participants who received at least 1 dose of any study drug (talazoparib or protocol-specified PCT).

Any medication (other than study drug) which was administered to participants during study after first dose of study drug were considered as concomitant medications.

Safety analysis population included all participants who received at least 1 dose of any study drug (talazoparib or protocol-specified PCT).

DOR = time from first radiographic documentation of OR (PR or CR) till radiographic disease progression (PD) as per RECIST v1.1 by investigator assessment or to death due to any cause, whichever was first. RECIST 1.1, a) target lesion (TL): CR= disappearance of all non-nodal TL, target lymph nodes reduce to <10 mm in short axis, PR= at least 30% decrease in sum of diameters of TL, compared to the sum at baseline, PD= at least 20% increase in sum of TL measurements, compared to smallest sum on study including baseline, absolute increase in sum has to be at least 5 mm; b) for non-TL: CR= disappearance of all non-TL, PD= unequivocal progression of non-TL, such that treatment has failed, disease is progressing, regardless of status of TL; c) PD =and/or appearance of >=1 new lesions. DOR = (earliest date of progression, death, or censoring-date of first documented OR + 1)/30.4375. Analysis was performed by Kaplan-Meier method.

ITT with measurable disease analysis population included all participants in the ITT population who had at least 1 target lesion identified at baseline.

EORTC QLQ-C30: cancer-specific instrument with 30 questions to assess the participant QoL. First 28 questions used to evaluate 5 functional scales (physical, role, cognitive, emotional, social), 3 symptom scales (fatigue, nausea and vomiting, pain) and other single items (dyspnea, appetite loss, insomnia, constipation, diarrhea, financial difficulties). Each question assessed on 4-point scale (1= not at all, 2= a little, 3= quite a bit, 4= very much); functional scales: higher score = better level of functioning; symptom scale: higher score = more severe symptoms; for single items: higher score= more severe problem. Last 2 questions used to evaluate global health status (GHS)/QoL. Each question was assessed on 7-point scale (1= very poor to 7= excellent). Scores averaged, transformed to 0-100 scale; higher score=better quality of life/better level of functioning. Change from baseline was calculated by subtracting the baseline value from the average value of Week 4 to 160.

Patient-reported outcomes (PRO) evaluable population included all participants who completed the PRO questionnaire at baseline and at least 1 visit post-baseline.

TTD in global health status (GHS)/QoL=time (in months) from randomization to the first observation with >=10 point decrease and no subsequent observations with<10 point decrease from baseline in GHS/QoL score based on EORTC-QLQ-C30. EORTC QLQ-C30 is a cancer-specific instrument with 30 questions to assess participant quality of life. Question 29 and 30 were used to evaluate GHS/QoL. Each question was assessed on a 7-point scale (1=very poor to 7=excellent). Scores averaged, transformed to 0-100 scale; higher score=better quality of life/better level of functioning.

PRO-evaluable population included all participants who completed the PRO questionnaire at baseline and at least 1 visit post-baseline.

TTD was defined as the time (in months) from randomization to the first observation with a>=10 point increase and no subsequent observations with a <10 point increase from baseline in breast symptom score based on the EORTC-QLQ-BR23. EORTC-QLQ-BR23 is a disease-specific module for breast cancer developed as a supplement for the EORTC-QLQ-C30 to assess the quality of life of participants with breast cancer. EORTC-QLQ-BR23 symptoms subscale includes 4 items: systemic therapy side effects, breast symptoms, arm symptoms, upset by hair loss. Each item is rated by choosing 1 of 4 possible responses that record the level of intensity (1= not at all, 2= a little, 3= quite a bit, and 4= very much), higher scores=high level of symptom/problems.

PRO-evaluable population included all participants who completed the PRO questionnaire at baseline and at least 1 visit post-baseline.