This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Phase II Trial of Talazoparib in BRCA1/2 Wild-type HER2-negative Breast Cancer and Other Solid Tumors (NCT02401347), a non-randomized phase 2 study. The primary outcome is Objective Response (OR).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02401347 |
| Phase | Phase 2 |
| Condition | Advanced Breast Cancer, HER2/Neu Negative, Triple-Negative Breast Cancer |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 21 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Melinda Telli |
| Results posted | Yes |
2. Clinical Question
Population
Participants had advanced triple-negative breast cancer with homologous recombination deficiency, or advanced HER2-negative breast cancer or other solid tumors with a mutation in a homologous recombination pathway gene. The registry also describes the eligible population as including patients with either triple-negative or HER2-negative breast cancer. Total enrollment was 21.
Intervention
The intervention was talazoparib, also called BMN 673 in the registry summary. Participants in Cohort A received talazoparib 1 mg by mouth daily. The dose description for Cohort B is incomplete in the registry record.
Comparator
There was no randomized control group. The trial was non-randomized and had parallel cohorts; these cohorts represent different eligibility groups, not like-for-like treatment comparison groups.
Primary question
The primary endpoint counted participants who achieved a complete or partial response under RECIST v1.1 within 24 weeks after starting treatment. The registry record does not report the number who achieved this endpoint.
Statistically, the question is whether an objective response was observed among participants treated in each eligible disease group. Because the trial was single-arm rather than randomized, it cannot estimate a treatment contrast against a concurrent control group. The distinct cohort definitions also matter: Cohort A consisted of participants with advanced triple-negative breast cancer and homologous recombination deficiency assessed by the Myriad HRD Assay, while Cohort B covered advanced HER2-negative solid tumors with specified hereditary or somatic mutations. Those populations should not be treated as interchangeable.
The registry lists clinical benefit and progression-free survival as secondary outcomes, but their results are not reported in the registry record. The primary response endpoint is also not reported as a result. Consequently, the record does not answer how many participants responded, how responses were distributed between cohorts, or how uncertain any response estimate would be. The question is defined, but the posted information does not provide the outcome data needed to evaluate it.
3. Trial Design
This was a phase 2, non-randomized, open-label trial with parallel cohorts. The registry status is completed, and total enrollment is listed as 21. The trial began in 2015-08, and primary completion is listed as 2019-12-23. These registry dates describe the record and do not provide additional outcome information.
The cohorts were organized around different disease and genomic eligibility criteria. Cohort A included participants with advanced triple-negative breast cancer and homologous recombination deficiency based on the Myriad HRD Assay. Cohort B included participants with advanced HER2-negative solid tumors and a deleterious hereditary or cancer somatic mutation in a listed homologous recombination pathway gene. The listed genes include PTEN, PALB2, CHEK2, ATM, NBN, BARD1, BRIP1, RAD50, RAD51C, RAD51D, MRE11, ATR, and Fanconi anemia complementation group genes. Cohort A's treatment description specifies talazoparib 1 mg by mouth daily. The available description of Cohort B's dose is truncated, so its complete dosing information is not reported in the registry record.
Non-randomized allocation means that participants were not assigned at random to talazoparib or a control treatment. There was no masking. The cohort labels therefore define groups with different eligibility profiles; they do not create a randomized comparison. Differences between cohorts could reflect their distinct disease types and genomic criteria as well as other participant characteristics. An observed difference between cohorts, if available, would not by itself isolate a treatment effect.
The registry record does not report a separate control arm, a statistical analysis plan, a sample-size justification, interim analyses, or a detailed plan for handling missing data. It lists three outcome measures and zero posted analyses. The record also does not report participant flow, cohort-specific enrollment, or the analysis populations used for the primary endpoint. These omissions limit assessment of how the planned design was implemented and how the outcome was analyzed.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Cohort A - Triple-negative Breast Cancer | Cohort B - HER2-negative Solid Tumor |
|---|---|---|
| STARTED | 1 | 20 |
| COMPLETED | 1 | 20 |
| NOT COMPLETED | 0 | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Cohort A - Triple-negative Breast Cancer | Cohort B - HER2-negative Solid Tumor | Total |
|---|---|---|---|---|
| Participants analysed | 1 | 20 | 21 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 15 | 16 |
| Age, Categorical: >=65 years | Participants | 0 | 5 | 5 |
| Age, Continuous | years | 42.5 (SD NA) | 53.8 (SD 9.6) | 53.6 (SD 9.7) |
| Sex: Female, Male: Female | Participants | 1 | 15 | 16 |
| Sex: Female, Male: Male | Participants | 0 | 5 | 5 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 1 | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 1 | 19 | 20 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 4 | 4 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): White | Participants | 0 | 15 | 15 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 1 | 20 | 21 |
6. Primary Endpoint
The registry lists the primary outcome as Objective Response (OR), measured over up to 24 weeks.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint was objective response, expressed as the number of participants who achieved a complete response or partial response within 24 weeks of starting treatment. Response was defined using RECIST v1.1. The registry describes assessment using physical measurement and imaging approaches including MRI, CT, PET-CT, and X-rays. A complete response means disappearance of all target and non-target lesions. A partial response requires a decrease of at least 30% in the sum of the long diameter of target lesions. Objective response combines complete and partial responses. Stable disease describes changes that do not meet those response or progression criteria; progressive disease includes an increase of at least 20% in long diameter of target lesions or the appearance of new lesions.
Objective response is used as a binary endpoint: each participant either meets the response definition within the stated timeframe or does not. Reporting the count gives a direct description of how many participants met the criterion, but a count alone does not show the precision of an estimated response rate. A confidence interval, when reported, can convey uncertainty around an estimate; no confidence interval is reported for this endpoint in the registry record.
The endpoint's definition and assessment window are reported, but the outcome count is not. The registry record therefore does not state how many participants achieved a complete or partial response. It also does not report cohort-specific response counts, response assessments by imaging method, or reasons an endpoint could not be assessed. Without those results, the endpoint can be described but its observed frequency cannot be evaluated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines the primary outcome as the count of participants with an objective response within 24 weeks, but does not report the observed count. No response estimate, confidence interval, or statistical test for the primary endpoint is reported in the registry record. As a result, the posted information cannot establish the frequency of response in the enrolled participants or the precision of any estimate. It also does not support a conclusion about treatment benefit or lack of benefit.
The total enrollment was 21, but that number alone cannot substitute for the missing endpoint result. The number enrolled does not reveal how many participants had an evaluable response assessment, how many met the response definition, or how missing assessments were handled. Cohort-specific enrollment and primary outcome counts are not reported in the registry record, so response findings cannot be compared across the two eligibility groups.
The trial's non-randomized design is central to interpretation. There was no concurrent randomized control group, and the two cohorts had different eligibility criteria. Thus, even if response counts were available, the design would provide descriptive evidence from treated participants rather than a randomized estimate of the difference between talazoparib and another treatment or no treatment. A cross-cohort comparison would also be difficult to interpret because disease types and genomic eligibility differ.
The registry lists clinical benefit and progression-free survival as secondary outcomes, but does not report their results in the available record. The absence of posted results does not mean that no response or other outcome occurred; it means those results are not reported in the registry record. The record lists zero analyses, and does not report p-values, interval estimates, adjusted analyses, or a multiplicity strategy.
Safety information is present in the registry record and should be read separately from efficacy. The adverse-event listings include counts of participants at risk, counts with serious and other adverse events, and deaths in each cohort. These are descriptive counts. The record does not establish whether any event or death was caused by treatment, nor does it provide a randomized comparison for safety. Small cohort denominators also make the posted counts difficult to generalize beyond the participants recorded.
Overall, the most defensible statistical reading is limited: the record describes a phase 2 study, defines its primary response endpoint, and posts selected safety counts, but does not report the primary efficacy result. Without the endpoint counts and analysis details, the magnitude and uncertainty of the clinical outcome cannot be assessed from the registry record.
9. Statistical Methods Explained
The registry describes a binary primary outcome reported as a count of participants. Each participant's response assessment is classified according to the RECIST v1.1 definitions, and the endpoint counts those with complete or partial response within 24 weeks. This kind of endpoint is straightforward to state, but its interpretation depends on clear assessment rules, an appropriate observation window, and disclosure of the number assessed as well as the number meeting the criterion. The record defines the endpoint but does not report its result or the assessment denominator.
What does a binary endpoint show?
In general, a binary outcome records whether an event or state occurred for each participant. A count can describe the observed number meeting a definition. To estimate the frequency of that outcome, the count must be interpreted alongside the relevant number of participants assessed. The registry identifies the primary outcome unit as participants, but does not report the response count or the number included in its analysis. A response rate and its uncertainty therefore cannot be described from this record.
In general, a confidence interval communicates the range of values compatible with the observed data under the method used. It reflects statistical uncertainty and is not a guarantee that the true value lies in that range. Confidence intervals are especially useful for distinguishing a relatively precise estimate from one that is highly uncertain. No confidence interval for objective response is reported in the registry record, so the precision of the response result cannot be evaluated.
Why does the design affect interpretation?
The trial was non-randomized, with no masking and parallel cohorts. In general, random allocation helps make groups comparable, on average, with respect to measured and unmeasured characteristics. Without randomization, comparisons can be affected by differences in who enters each group. Here, the cohorts were defined by different clinical and genomic characteristics, so they are not like-for-like controls. Their comparison would not estimate the effect of talazoparib relative to a control treatment.
In a single-arm setting, an outcome count describes what was observed among treated participants. It does not by itself tell what would have happened to the same participants under a different treatment or without the study treatment. Historical or external comparisons require their own assumptions and methods; no such comparison is reported in the registry record. The record also does not report a statistical analysis plan that would clarify any planned adjustment or comparison.
What can the safety counts tell readers?
The safety information is presented as counts of participants at risk and participants affected, separated by cohort and event category. In general, a denominator is important because the same count can represent different levels of observed frequency in groups of different sizes. These counts are descriptive, not a causal estimate. A serious event recorded during a study is not necessarily caused by the treatment, and a death count does not establish a treatment relationship. The registry record does not report causal attribution or a control-group safety comparison.
Small denominators can make observed proportions unstable: a change in the experience of one participant can substantially alter the description of a small group. General statistical reasoning therefore cautions against treating a small-cohort count as a precise estimate of what would occur in a broader population. No new frequency estimates are calculated. The record's safety counts should be understood as observations among the listed participants, not as a prediction for other patients.
How should planning calculations be understood?
In general, sample-size planning asks how many participants would be needed to detect a specified effect under stated assumptions. A planning illustration is conditional on its assumptions; it is not the number of participants actually observed, and it is not observed power. The registry's stated illustration assumptions include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of the observed effect. The record states that time-to-event illustrations use a total event count, while other illustrations use participants per arm.
Those planning assumptions do not describe the trial's own design: this study was non-randomized and organized into distinct cohorts. The sample-size justification for the trial is not reported in the registry record. No planning values are included in the record information, so no required sample size can be inferred. Any sample-size illustration should be treated as hypothetical planning information, not as evidence that the study had a particular probability of detecting an effect.
What analysis details remain unknown?
The registry record lists zero analyses. It does not report a method for estimating response, a confidence-interval procedure, a test, an adjustment strategy, handling of missing outcome assessments, or the analysis population. It also does not report interim analyses or a sample-size justification. These omissions matter because different reasonable choices can affect which participants contribute to an endpoint and how uncertainty is described. Without the analysis details and outcome data, the primary endpoint cannot be independently interpreted beyond its stated definition.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures, including objective response as the primary outcome and clinical benefit and progression-free survival as secondary outcomes. It does not report results for the primary or secondary outcomes in the registry record. Zero analyses are listed. A multiplicity strategy—how statistical interpretation would account for examining multiple outcomes or analyses—is not reported in the registry record.
In general, when several outcomes or statistical tests are considered, the chance of at least one apparently notable result can increase. A prespecified hierarchy, adjustment procedure, or clearly descriptive interpretation can help readers understand how multiple findings should be viewed. The record does not state whether any such approach was planned, and no adjusted or unadjusted test results are reported. It is therefore not possible to assess how multiplicity was handled.
Missing-data handling is also not reported in the registry record. The primary endpoint has a defined assessment window of up to 24 weeks, but the record does not say how participants without an assessment in that window were classified, whether incomplete follow-up affected endpoint inclusion, or what analysis population was used. These details are important for a binary response outcome because the count and its denominator depend on how unevaluable participants are treated.
The record does not report participant flow, the number assessed for each outcome, or reasons for missing assessments. It also does not report whether analyses followed an intention-to-treat, per-protocol, or other population definition. No assumptions should be made about those choices. The posted endpoint definition is useful, but without missing-data and multiplicity details, readers cannot determine how robust any analysis would be even if outcome estimates were available.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Cohort A - Triple-negative Breast Cancer | 0 | 1 | 0.0% |
| Cohort B - HER2-negative Solid Tumor | 3 | 20 | 15.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cohort A - Triple-negative Breast Cancer | 1 of 1 |
| Cohort B - HER2-negative Solid Tumor | 9 of 20 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Cohort A - Triple-negative Breast Cancer | 1 of 1 |
| Cohort B - HER2-negative Solid Tumor | 20 of 20 |
Most frequent serious adverse event terms
| Event term | Organ system | Cohort A - Triple-negative Breast Cancer | Cohort B - HER2-negative Solid Tumor |
|---|---|---|---|
| Thrombocytopenia | Investigations | 0 of 1 | 1 of 20 |
| Hyponatremia | Metabolism and nutrition disorders | 0 of 1 | 1 of 20 |
| Weakness in extremity, right leg, progressing | Musculoskeletal and connective tissue disorders | 0 of 1 | 1 of 20 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 0 of 1 | 1 of 20 |
| Weakness in extremities, right side | Musculoskeletal and connective tissue disorders | 0 of 1 | 1 of 20 |
| Intracranial masses, supratentorial and infratentoria | Nervous system disorders | 0 of 1 | 1 of 20 |
| Pneumothorax, post-lung biopsy | Respiratory, thoracic and mediastinal disorders | 0 of 1 | 1 of 20 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cohort A - Triple-negative Breast Cancer | Cohort B - HER2-negative Solid Tumor |
|---|---|---|---|
| Nausea | Gastrointestinal disorders | 0 of 1 | 9 of 20 |
| Fatigue | General disorders | 0 of 1 | 9 of 20 |
| Constipation | Gastrointestinal disorders | 0 of 1 | 7 of 20 |
| Platelet count decreased | Investigations | 0 of 1 | 7 of 20 |
| Anemia | Blood and lymphatic system disorders | 1 of 1 | 4 of 20 |
| Alkaline phosphatase increased | Investigations | 0 of 1 | 5 of 20 |
| Neutropenia | Investigations | 0 of 1 | 5 of 20 |
| Anorexia | Metabolism and nutrition disorders | 0 of 1 | 5 of 20 |
| Back pain | Musculoskeletal and connective tissue disorders | 0 of 1 | 5 of 20 |
| Vomiting | Gastrointestinal disorders | 0 of 1 | 3 of 20 |
Serious events with the highest arm-level rate: thrombocytopenia (5.0%), hyponatremia (5.0%), weakness in extremity, right leg, progressing (5.0%), pain in extremity (5.0%), weakness in extremities, right side (5.0%).
The registry reports safety counts separately for Cohort A and Cohort B. For serious adverse events, the count at risk was 1 in Cohort A, with 0 affected, and 20 in Cohort B, with 3 affected. For other adverse events, the count at risk was 1 in Cohort A, with 1 affected, and 20 in Cohort B, with 20 affected. Deaths are listed as 1 in Cohort A and 9 in Cohort B. These are counts in the registry record, not comparative treatment-effect estimates.
The record also lists serious adverse event terms with a reported 5.0% for each: thrombocytopenia, hyponatremia, right-leg weakness progressing, pain in extremity, right-sided weakness in extremities, and intracranial masses described as supratentorial and infratentorial. These entries do not establish that the events were caused by talazoparib. Nor do the death counts establish that deaths were treatment-related; causal attribution is not reported in the registry record.
The cohort denominators are small, and the cohorts have different eligibility criteria. Counts should therefore be read as descriptions of participants recorded in this trial, not as precise estimates for a broader population or as a comparison between treatments. The record does not provide a randomized control group or additional context on timing, attribution, or participant-level overlap among event categories.
12. What the Result Does, and Does Not, Mean
The record establishes that a phase 2, non-randomized trial evaluated talazoparib in participants with advanced breast cancer or other solid tumors meeting specified genomic eligibility criteria. It defines objective response using RECIST v1.1 and sets the assessment window as up to 24 weeks. It also posts selected adverse-event and death counts. These registry entries describe the trial and some recorded safety observations.
The record does not report the primary response count, a response estimate, or its uncertainty. It also does not report the secondary outcome results. Therefore, it cannot show from the posted information how often objective response occurred, how consistent the response findings were across cohorts, or how precisely an outcome was estimated. The absence of a posted result is not evidence that no responses occurred.
The design does not provide a randomized control comparison. Any outcome among treated participants would be descriptive of this study population, not a direct estimate of what would happen under a different treatment. The two cohorts differ by disease and genomic eligibility, so comparisons between them would not isolate a treatment effect. Safety counts likewise do not establish causation or quantify a difference against a control group.
Important analysis details are not reported in the registry record, including the sample-size justification, statistical analysis plan, treatment of missing response assessments, analysis populations, and multiplicity approach. Without these details and the primary endpoint result, readers cannot evaluate the statistical strength or precision of the efficacy findings. The appropriate conclusion is limited to the information actually posted: the trial design and endpoint are described, but the registry record does not report the efficacy result needed to assess the primary question.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of how a biologically selected phase 2 study can define a response question in distinct patient groups. Eligibility depended on disease subtype and homologous recombination pathway features, and the primary outcome used a recognizable radiologic response framework, RECIST v1.1. The record specifies the response window and describes what qualifies as complete or partial response. These definitions make the intended endpoint understandable.
At the same time, the study illustrates why design and reporting must be considered together. Non-randomized cohorts can describe outcomes in selected participants, but they do not create a randomized treatment comparison. The separate eligibility criteria also mean that the cohorts are not interchangeable controls. Readers need outcome counts, denominators, uncertainty estimates, and analysis details to judge what a study's observations can support.
In this record, the primary objective response result is not reported. That absence sharply limits statistical interpretation despite the explicit endpoint definition and total enrollment of 21. The posted safety counts provide some descriptive information, but their small denominators and lack of a control group limit broader inference. The sample-size justification and statistical analysis plan are also not reported.
The key statistical lesson is that a clearly defined endpoint is only one part of an interpretable trial record. Transparent reporting of participant flow, endpoint results, uncertainty, missing-data decisions, and analysis methods is needed to connect the design to a credible estimate. Without those elements, the clinical question can be identified, but the result cannot be evaluated from the registry record.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main trial-specific limitation in the registry record is that it does not report the primary objective response result. The count of participants achieving complete or partial response, the number assessed, and any estimate of uncertainty are not reported. Cohort-specific response outcomes are also not reported. This prevents evaluation of the endpoint the trial was designed to assess.
The non-randomized design has no control group, and the two cohorts have distinct disease and genomic eligibility criteria. The record therefore does not support a randomized treatment comparison, and comparisons between cohorts would be confounded by their different eligibility profiles. The trial is listed as completed, but the available registry information does not provide participant flow or explain how total enrollment was distributed across the cohorts for efficacy analyses.
Other important details are not reported in the registry record: the sample-size justification, a statistical analysis plan, interim analyses, the analysis populations, handling of missing endpoint assessments, and a multiplicity strategy. The Cohort B dose description is incomplete in the record. The safety data are descriptive, with small listed denominators, and do not provide treatment attribution or a control comparison. Death counts should not be interpreted as treatment-related without attribution information.
The registry lists three outcome measures but reports no analyses. Taken together, these gaps mean that the endpoint definition and selected safety counts can be described, but the efficacy result, its precision, and the robustness of any analysis cannot be assessed from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Phase II Trial of Talazoparib in BRCA1/2 Wild-type HER2-negative Breast Cancer and Other Solid Tumors — NCT02401347.
- Registry record last updated 2023-02-21; status last verified 2023-02.
- Results first posted 2023-02-21.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT02401347 is a completed, non-randomized phase 2 trial of talazoparib in advanced breast cancer and other solid tumors with specified homologous recombination pathway features. Total enrollment was 21. The trial used parallel cohorts without masking. Cohort A comprised participants with advanced triple-negative breast cancer and homologous recombination deficiency; Cohort B comprised participants with advanced HER2-negative solid tumors and specified hereditary or somatic mutations.
The primary endpoint was the number of participants with complete or partial response under RECIST v1.1 within 24 weeks. The primary endpoint result and secondary outcome results are not reported in the registry record. The record lists selected serious adverse event, other adverse event, and death counts, but does not establish treatment causation. It does not report the statistical analysis plan, sample-size justification, missing-data approach, or analysis populations.