A Phase 2, 2-Stage, 2-Cohort Study of Talazoparib (BMN 673), in Locally Advanced and/or Metastatic Breast Cancer Patients With BRCA Mutation (ABRAZO Study)

CBR24: Percentage of participants with a best response of CR, PR or stable disease (SD) sustained for at least 24 weeks, as assessed by IRF using RECIST 1.1. CR: Disappearance of all non-nodal target and non-target lesions, including target and non-target lymph nodes reduction to <10 mm in short axis. PR: >=30% decrease in sum of diameters of target lesions, compared to the sum at baseline. SD: Neither PR nor progression of disease (PD) criteria met. SD follow PR only when sum increases by less than 20% from the nadir, but previously seen 30% decrease from baseline no longer hold. PD: >=20% increase (>=5 mm absolute increase) in the sum of target lesion measurements, compared to the smallest sum on study (including baseline), or 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.

DOR: Time from first documentation of CR or PR, to PD by IRF assessment using RECIST 1.1, or to death due to any cause, whichever occurred first. CR: Disappearance of all non-nodal target and non-target lesions, with target and non-target lymph nodes reduction to <10 mm in short axis. PR: >=30% decrease in sum of diameters of target lesions, compared to the sum at baseline. PD: >=20% increase (>=5 mm absolute increase) in the sum of target lesion measurements, compared to the smallest sum on study (including baseline), or 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. Participants with no PD or death at the analysis date were censored at last tumor assessment date prior to on or before initiation of a new anticancer therapy or before the data cutoff date.

PFS was defined as the time in months from the first dose of study drug to the first documentation of PD by investigator assessment using RECIST 1.1 or death on study due to any cause on or before the data cutoff date, whichever occurred first. PD: >=20% increase (>=5 mm absolute increase) in the sum of target lesion measurements, compared to the smallest sum on study (including baseline), or 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. Participants with no PFS event at the analysis were censored at last tumor assessment date prior to data cutoff or date of new anticancer treatment initiation, whichever occurred first.

OS was defined as the time from first dose of study drug to death due to any cause. For participants without a death date at the time of data cutoff or permanently lost to follow-up, OS was right-censored at the date the participant was last known to be alive on or before the data cutoff date.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. 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; an important medical event or reaction, including events requiring medical intervention to prevent worsening to any of the previously noted seriousness criteria. A treatment emergent AE was defined as an event that emerged during the treatment period that was absent before treatment, or worsened during the treatment period relative to the pretreatment state. AEs included both serious and non-serious AEs.

A treatment-related AE was any untoward medical occurrence attributed to study drug in a participant who received study drug. A treatment-related SAE was a treatment-related 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; an important medical event or reaction, including events requiring medical intervention to prevent worsening to any of the previously noted seriousness criteria. Related TEAEs are TEAEs that were judged by the investigators as possibly, probably, or definitely related to study drug. AEs included both SAES and non SAES.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Outcome of an AE was response to a question answered by the investigator: 'Is the AE leading to study discontinuation or death?' as 'yes'.

Laboratory tests included hematology (hemoglobin [low], leucocytes [low], lymphocytes [low], neutrophils [low], platelets [low]). Toxicity grades were evaluated based on national cancer institute- common terminology criteria for adverse events (NCI-CTCAE) version 4.03. Number of participants with increase of 2 or more CTCAE toxicity grades above baseline, for hematology laboratory parameter is reported in this outcome measure.

Laboratory tests included serum chemistry (alanine aminotransferase [high], albumin [low], alkaline phosphatase [high], aspartate aminotransferase [high], bilirubin [high], calcium [low], glucose [high], magnesium [low], phosphate [low], potassium [high], potassium [low], sodium [high], sodium [low]). Toxicity grades were evaluated based on national cancer institute- common terminology criteria for adverse events (NCI-CTCAE) version 4.03. Number of participants with increase of 2 or more CTCAE toxicity grades above baseline, for chemistry laboratory parameter is reported in this outcome measure.

Criteria for clinically significant vital signs changes: 1) Blood pressure: systolic blood pressure (SBP): greater than or equal to (>=30) millimeters of mercury (mmHg) increase from baseline, diastolic blood pressure (DBP): >=20 mmHg decrease from baseline; 2) Heart rate (HR): absolute HR greater than (>) 120 beats per minute (bpm) and >30 bpm increase from baseline, absolute HR less than (<) 50 bpm and >20 bpm decrease from baseline; 3) Weight: >10% decrease from baseline. Number of participants with any clinically significant change from baseline for blood pressure, heart rate and weight are reported in this outcome measure.

Physical examination included examination of the head, ears, eyes, nose, mouth, skin, heart and lung examinations, lymph nodes, gastrointestinal, musculoskeletal, and neurological systems. The examination assessed the participants for any potential changes in general appearance, the respiratory and cardiovascular systems, as well as towards participant reported symptoms. Findings were considered to be clinically significant based on investigator's decision.

Number of participants taking any non-study medications, therapies, including herbal supplements during the treatment-emergent period for the management of an adverse event or for the treatment of any other disease.

Concentrations below the limit of quantitation values less than or equal to (<=) 25 picogram per milliliter (pg/mL) were set as zero. Pharmacokinetic (PK) analysis was not done separately for each reporting arm and cohorts were combined for PK analysis.