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 Abraxane® With or Without Mifepristone for Advanced, Glucocorticoid Receptor-Positive, Triple-Negative Breast Cancer (NCT02788981), a randomized phase 2 study. The primary outcome is Progression-free Survival (PFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02788981 |
| Phase | Phase 2 |
| Condition | Breast Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 29 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Chicago |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerns people with advanced, glucocorticoid receptor-positive, triple-negative breast cancer. The registry lists breast cancer as the condition and describes glucocorticoid receptor positivity and triple-negative disease in the trial title and summary. Further eligibility criteria, including how receptor positivity was defined, are not reported in the registry record. The primary endpoint population field is blank, so the record does not specify a separate population for that outcome.
Intervention
Participants assigned to the intervention arm receive nab-paclitaxel with mifepristone. The listed schedule is mifepristone 300 mg daily on the day before and the day of each nab-paclitaxel dose. Nab-paclitaxel is listed as 100 mg/m2 on days 1, 8 and 15 of each 28 day cycle.
Comparator
The comparison arm receives nab-paclitaxel with placebo. The listed nab-paclitaxel dose and schedule are 100 mg/m2 on days 1, 8 and 15 of each 28 day cycle. The placebo is intended to make the randomized comparison double-blind; details of how masking was maintained are not reported in the registry record.
Primary question
The primary question is whether the posted progression-free survival results differ between the two assigned treatment groups. The endpoint is listed as median progression-free survival, measured using RECIST guideline v1.1, with a 12 months timeframe. The registry reports a median of 3.0 months in each arm. The record does not post a hazard ratio, p value, or other sponsor-reported statistical comparison, so these medians alone do not establish the size or statistical certainty of a between-group difference.
3. Trial Design
This is a randomized, placebo-controlled, double-blind, parallel-group phase II trial. It compares nab-paclitaxel plus mifepristone with nab-paclitaxel plus placebo in advanced, glucocorticoid receptor-positive, triple-negative breast cancer. Random allocation and a placebo comparator are intended to support a fair comparison by reducing systematic differences between groups and limiting knowledge of assignment during the trial. The record does not describe the randomization procedure, allocation concealment, or how blinding was implemented.
The listed mifepristone schedule is 300 mg daily on the day before and day of each nab-paclitaxel dose. Both arms list nab-paclitaxel 100 mg/m2 on days 1, 8 and 15 of each 28 day cycle. The registry lists University of Chicago as sponsor. It records the trial as active, not recruiting, and lists a start date of 2017-03-28 and primary completion date of 2022-12-21.
The registry lists enrollment 29, while the brief summary says that a total of 64 patients will receive nab-paclitaxel. The record does not explain how these enrollment figures relate or whether the summary describes a planned target or a later status. Posted primary outcome arm records list 13 participants for each arm; the record does not explain how those outcome populations relate to the enrollment entry. The summary describes enrollment over 12 months and follow-up for 12 months after study completion as planned. Whether those plans were followed is not reported in the registry record.
The summary also describes pharmacokinetic studies in the first 20 patients enrolled at prespecified PK sites to investigate a potential interaction between nab-paclitaxel and mifepristone. Actual conduct or results of those studies are not reported in the registry record. The sample-size justification and detailed statistical analysis plan are also not reported in the registry record.
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 | Nab-Paclitaxel+Mifepristone | Nab-Paclitaxel+Placebo |
|---|---|---|
| STARTED | 13 | 16 |
| COMPLETED | 13 | 15 |
| NOT COMPLETED | 0 | 1 |
Reasons for not completing this period:
| Reason | Nab-Paclitaxel+Mifepristone | Nab-Paclitaxel+Placebo |
|---|---|---|
| Patient chose to pursue alternative treatment | 0 | 1 |
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 | Nab-Paclitaxel+Mifepristone | Nab-Paclitaxel+Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 13 | 16 | 29 | |
| Age, Continuous | years | 57 (SD 13) | 49 (SD 10) | 53 (SD 12) |
| Sex: Female, Male: Female | Participants | 13 | 16 | 29 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 6 | 5 | 11 |
| Race (NIH/OMB): White | Participants | 5 | 9 | 14 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 | 2 | 3 |
| Region of Enrollment: United States | participants | 13 | 16 | 29 |
6. Primary Endpoint
The registry lists the primary outcome as Progression-free Survival (PFS), measured over 12 months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | months |
| Endpoint classification | Time-to-Event Analysis |
The primary endpoint is progression-free survival (PFS), reported as a median in months. In general, PFS is a time-to-event measure: it describes time until disease progression or death under the endpoint definition used by a trial. The registry specifies that progression is measured using RECIST guideline v1.1, but does not describe the complete event definition, assessment schedule, or handling of deaths and other events.
A median provides a point summary of the event-time distribution. In general, it marks the time by which half of the estimated population has experienced the event, subject to the analysis method and endpoint definition. It is useful because it summarizes the timing of events without requiring every participant to have the event observed during follow-up. The record does not report the method used to estimate the median or the confidence interval.
The timeframe is listed as 12 months. This does not, by itself, establish that every participant was followed for that duration or clarify how follow-up ended for individuals. Those details are not reported in the registry record. The posted median is 3.0 months in each arm; the associated 95% confidence intervals are 1.0 to 5.0 months for nab-paclitaxel plus mifepristone and 1.0 to 6.0 months for nab-paclitaxel plus placebo.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary outcome is a median PFS of 3.0 months in both randomized groups. The confidence interval for nab-paclitaxel plus mifepristone is 1.0 to 5.0 months; for nab-paclitaxel plus placebo it is 1.0 to 6.0 months. These intervals express uncertainty around each group’s median estimate. They do not provide a direct confidence interval for the difference between treatment groups.
Equal reported medians do not prove that the full time-to-event distributions are identical. A median compresses the distribution into one summary and can conceal differences at other points in follow-up. Conversely, the different upper confidence limits do not establish a difference between arms. The registry does not report a sponsor-estimated hazard ratio, confidence interval for a between-arm effect, p value, or other formal primary comparison. The record therefore does not support a conclusion about the statistical evidence for a treatment effect based on a direct comparison.
The number of participants listed with each primary outcome result is 13 in the mifepristone arm and 13 in the placebo arm. These are the outcome entries posted for the endpoint, not necessarily a description of every participant enrolled or of the analysis population. The registry does not explain the relationship between these entries and the enrollment figure, nor does it state how participants without an observed event were handled.
In general, a confidence interval describes the precision of an estimate under the statistical method used: a wider interval indicates less precision than a narrower interval on the same scale. The intervals show that the medians are estimates rather than exact known event times for a broader population. Their overlap is not a substitute for a formal treatment comparison, and no significance test should be inferred from the medians or intervals alone.
The registry lists three secondary outcomes: response rate in glucocorticoid receptor positivity, response rate, and overall survival. Their inclusion identifies additional outcomes of interest, but the record does not provide posted estimates or analysis details for them in the registry record described. No result for those outcomes should be inferred from the primary PFS figures. The record lists no analyses, and the sponsor’s detailed statistical plan is not reported in the registry record.
The brief summary describes a pharmacokinetic investigation at selected sites, but no pharmacokinetic findings are reported in the registry record. The primary PFS results therefore should not be interpreted as resolving whether a pharmacokinetic interaction occurred. Overall, the posted PFS data give the separate arm medians and their uncertainty, but do not give a sponsor-reported estimate of the comparative effect or its statistical precision.
9. Statistical Methods Explained
The primary outcome is a time-to-event endpoint summarized by its median. Time-to-event methods are designed for outcomes where the timing of an event matters and where some participants may not have an event observed during their available follow-up. In general, those participants can contribute information up to the time they are last known to be event-free, depending on the analysis approach. The registry does not report the censoring rules or the method used to estimate PFS.
What does the median describe?
In general, the median event time is the point at which the estimated proportion remaining event-free reaches half, under the endpoint definition and analysis method. It is a useful summary when event times are skewed or follow-up varies. It does not describe every part of the event-time distribution, and groups with the same median can have different distributions. The posted median is 3.0 months in each arm. The registry does not report further points on the PFS curves or the curves’ shapes.
How should the confidence intervals be read?
A confidence interval communicates statistical uncertainty around an estimate. In general, an interval is constructed using a method with stated repeated-sampling properties, but the exact method used for the intervals is not reported in the registry record. The interval for the mifepristone arm is 1.0 to 5.0 months, and the interval for the placebo arm is 1.0 to 6.0 months. These are intervals around each arm’s median, not a confidence interval for the difference between arms. They do not, on their own, answer whether the treatments differ statistically.
Why is a direct comparison important?
Randomization supports comparison between assigned groups, but interpretation of a treatment effect ordinarily depends on a direct contrast that reflects the design and endpoint. For time-to-event outcomes, a study may report a hazard ratio or another prespecified comparative measure with uncertainty. The registry does not report such a sponsor analysis for PFS. A difference between two separate summaries, or their intervals, cannot be substituted for the missing comparative analysis. The record identifies no analyses, and the sponsor’s statistical model and testing procedure are not reported in the registry record.
What do the planning illustrations mean?
Planning illustrations based on an observed effect are not observed power and are not evidence that the trial was designed to detect that effect. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The illustrations consider an effect to detect expressed as a stated fraction of the observed effect. For time-to-event outcomes, the planning calculation is expressed as a total number of events using the Schoenfeld approach; for other outcomes, it is expressed as participants per arm. These assumptions describe hypothetical planning calculations, not the trial’s original design or its achieved statistical power. The trial’s own sample-size justification is not reported in the registry record.
In general, time-to-event planning often depends on the number of observed events, because events contribute information about the relative event rate. Participant counts alone do not determine the information available: follow-up duration and event occurrence also matter. Over-dispersion, where outcomes vary more than a model assumes, can reduce the precision of estimates and make simple planning assumptions less realistic. This is a general statistical consideration; the registry does not report whether over-dispersion was considered or relevant to this trial.
What statistical details are absent?
The registry does not report the PFS estimation method, the comparative effect measure, the confidence interval method, the statistical model, or the planned hypothesis test. It also does not report interim analyses, a stopping rule, or how proportional hazards assumptions, if relevant, were assessed. These details should not be presumed from the fact that the endpoint is time-to-event or from the phase and randomized design. The posted results support description of the two median estimates and their intervals, but not reconstruction of an unreported sponsor analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry names three secondary outcomes: response rate in glucocorticoid receptor positivity, response rate, and overall survival. It does not report how these outcomes were defined in detail, when they were assessed, or what statistical tests or models were planned. A multiplicity strategy for interpreting several outcomes or tests is not reported in the registry record. Without such information, the record does not establish whether secondary findings were intended as confirmatory or exploratory, or how the risk of false-positive findings across multiple tests was addressed.
The record lists no analyses. It does not post secondary outcome estimates in the registry record described, so no conclusions about response or overall survival should be drawn from the PFS results. The detailed analysis population for the primary endpoint is also not reported. The primary endpoint population field is blank, and the registry does not say whether the analysis followed an intention-to-treat principle, a per-protocol approach, or another population definition.
Missing-data handling is not reported in the registry record. For a time-to-event endpoint, relevant details can include how participants who leave follow-up are handled, what event dates are used, and how censoring is defined. The record does not specify these procedures, the amount of missing outcome information, or whether sensitivity analyses were planned or performed. It also does not report how missing values for the secondary outcomes were handled. These omissions limit assessment of how robust the posted outcome summaries are to incomplete follow-up or outcome data.
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 |
|---|---|---|---|
| Nab-Paclitaxel+Mifepristone | 2 | 13 | 15.4% |
| Nab-Paclitaxel+Placebo | 0 | 15 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Nab-Paclitaxel+Mifepristone | 12 of 13 |
| Nab-Paclitaxel+Placebo | 14 of 15 |
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 |
|---|---|
| Nab-Paclitaxel+Mifepristone | 13 of 13 |
| Nab-Paclitaxel+Placebo | 12 of 15 |
Most frequent serious adverse event terms
| Event term | Organ system | Nab-Paclitaxel+Mifepristone | Nab-Paclitaxel+Placebo |
|---|---|---|---|
| Fatigue | General disorders | 1 of 13 | 0 of 15 |
| Anemia | Blood and lymphatic system disorders | 1 of 13 | 0 of 15 |
| Dehydration | Metabolism and nutrition disorders | 1 of 13 | 0 of 15 |
| Hypokalemia | Metabolism and nutrition disorders | 1 of 13 | 0 of 15 |
| Hypocalcemia | Metabolism and nutrition disorders | 1 of 13 | 0 of 15 |
| Hypophosphatemia | Metabolism and nutrition disorders | 1 of 13 | 0 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Nab-Paclitaxel+Mifepristone | Nab-Paclitaxel+Placebo |
|---|---|---|---|
| Fatigue | General disorders | 7 of 13 | 10 of 15 |
| Alopecia | Skin and subcutaneous tissue disorders | 6 of 13 | 7 of 15 |
| Neuropathy | Nervous system disorders | 8 of 13 | 5 of 15 |
| Dysgeusia | Nervous system disorders | 6 of 13 | 2 of 15 |
| Neutropenia | Investigations | 6 of 13 | 1 of 15 |
| Nausea | Gastrointestinal disorders | 2 of 13 | 4 of 15 |
| Diarrhea | Gastrointestinal disorders | 4 of 13 | 1 of 15 |
| Anorexia | Metabolism and nutrition disorders | 5 of 13 | 0 of 15 |
| Rash | Skin and subcutaneous tissue disorders | 3 of 13 | 2 of 15 |
| Anemia | Blood and lymphatic system disorders | 3 of 13 | 1 of 15 |
Serious events with the highest arm-level rate: fatigue (7.7%), anemia (7.7%), dehydration (7.7%), hypokalemia (7.7%), hypocalcemia (7.7%).
The registry reports serious adverse event counts by treatment group. In the nab-paclitaxel plus mifepristone group, 2 of 13 were reported as affected, with 13 at risk. In the nab-paclitaxel plus placebo group, 0 of 15 were reported as affected, with 15 at risk. The record also reports other, non-serious adverse event counts: 13 of 13 affected in the mifepristone group and 12 of 15 in the placebo group. These entries describe the posted group counts; the record does not provide further detail about event timing, duration, severity grading, or attribution to a particular treatment.
The top serious-event terms listed are fatigue, anemia, dehydration, hypokalemia, hypocalcemia, and hypophosphatemia, each reported as 7.7%. The record does not map these terms to a specific treatment group in the registry record described. It also lists deaths as 12 in the mifepristone group and 14 in the placebo group. The registry does not report the timing or causes of these deaths, or whether they were considered related to treatment. These counts should not be interpreted as evidence of causation or compared without accounting for the trial’s design and available follow-up information.
12. What the Result Does, and Does Not, Mean
The posted primary results show a median PFS of 3.0 months in each treatment group. The 95% confidence intervals are 1.0 to 5.0 months for nab-paclitaxel plus mifepristone and 1.0 to 6.0 months for nab-paclitaxel plus placebo. This is a description of the group-specific median estimates and their reported uncertainty. It is not a direct estimate of the treatment effect.
The results do not establish that the two treatment groups have identical PFS outcomes. Median values alone do not describe the entire event-time distribution, and the registry does not post a comparative hazard ratio or another sponsor-reported effect estimate. Nor do the posted values establish that one regimen is superior or inferior. The absence of a reported comparison is not evidence that a comparison found no difference; it means the comparative result is not available in the registry record.
The registry also does not report the complete PFS analysis methods, the analysis population, missing-data procedures, or the statistical plan. Those omissions matter when judging how estimates were produced and how precisely the treatment contrast is known. The posted figures can be read as outcome summaries, but they do not answer every question about the trial’s evidence.
The trial is a phase II study in a specific population: advanced, glucocorticoid receptor-positive, triple-negative breast cancer. The registry record alone does not establish how these results apply beyond that population or how they compare with other treatment approaches. The secondary outcomes and pharmacokinetic work are described in the record, but corresponding results are not reported in the registry record described. The safety counts likewise describe reported events and deaths without establishing cause or treatment attribution.
13. Why This Trial Matters Statistically
This trial illustrates why a randomized design and a treatment comparison are related but distinct pieces of statistical evidence. Random assignment is intended to make groups comparable on average, while the analysis must still quantify the difference in outcomes and its uncertainty. Here, the registry reports a median PFS of 3.0 months in each arm and a separate confidence interval for each median, but no sponsor-reported comparative estimate. A reader should not treat the two point estimates as a complete account of the randomized contrast.
It also demonstrates the limits of a median as a summary. Time-to-event outcomes contain information about event timing across follow-up; a single median cannot show all features of that distribution. Confidence intervals add information about uncertainty in each estimate, but intervals around separate medians are not the same as an interval around a treatment effect.
The record’s enrollment entries also highlight the importance of distinguishing planned descriptions, enrollment information, and outcome populations. The registry lists enrollment 29, the brief summary describes a total of 64 patients, and the posted primary outcome arms list 13 participants each. The registry does not explain how these figures relate. Statistical interpretation depends on knowing which participants contribute to each analysis and how follow-up and missing outcomes are handled.
Finally, the trial’s secondary outcomes, safety entries, and described pharmacokinetic work answer different questions from the primary PFS endpoint. Their presence in a record does not replace reported analyses or establish findings that are not posted. Clear separation of descriptive results, comparative estimates, and unreported methods is essential when interpreting a small phase II study.
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 registry record leaves important trial-specific details unresolved. It lists enrollment 29, while the brief summary describes a total of 64 patients; no explanation of the relationship between those figures is reported. The posted primary outcome arm entries each list 13 participants, and the record does not state how those endpoint populations relate to enrollment or whether other participants were excluded from the outcome analysis.
The primary outcome is specified as median PFS using RECIST guideline v1.1, but details of event definition, assessment timing, censoring, and median estimation are not reported. The record gives separate confidence intervals but no sponsor-reported hazard ratio, p value, or other comparative estimate. It also does not report the analysis population, missing-data procedures, or statistical analysis plan. Therefore, the posted medians cannot be used to reconstruct a treatment comparison.
The registry describes pharmacokinetic studies at prespecified PK sites but does not report their results. It names secondary outcomes without posting analyses in the registry record described. Safety entries provide counts and serious-event terms, but not event timing, treatment attribution, or causes of death. These limitations restrict interpretation of efficacy, safety, and pharmacokinetic findings.
The record’s dates and status describe the registration, but do not resolve whether planned enrollment and follow-up timelines were achieved. Generalization beyond the stated advanced, glucocorticoid receptor-positive, triple-negative breast cancer population is not established by this record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Abraxane® With or Without Mifepristone for Advanced, Glucocorticoid Receptor-Positive, Triple-Negative Breast Cancer — NCT02788981.
- Registry record last updated 2025-06-10; status last verified 2025-06.
- Results first posted 2024-02-16.
- 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
The registry describes a randomized, placebo-controlled, double-blind, parallel-group phase II trial sponsored by the University of Chicago. It compares nab-paclitaxel plus mifepristone with nab-paclitaxel plus placebo for advanced, glucocorticoid receptor-positive, triple-negative breast cancer. The primary endpoint is median PFS measured using RECIST guideline v1.1, with a listed timeframe of 12 months.
The posted median is 3.0 months in each arm. The 95% confidence interval is 1.0 to 5.0 months for mifepristone and 1.0 to 6.0 months for placebo. No sponsor-reported comparative PFS estimate is listed. The registry lists enrollment 29, while its brief summary describes a total of 64 patients; this difference is not explained in the record. Statistical analysis details, missing-data methods, and secondary outcome analyses are not reported in the registry record.