Efficacy and Safety of GTx-024 in Patients With Androgen Receptor-Positive Triple Negative Breast Cancer (AR+ TNBC): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of GTx-024 in Patients With Androgen Receptor-Positive Triple Negative Breast Cancer (AR+ TNBC) (NCT02368691), a na phase 2 study. The primary outcome is Clinical Benefit Rate, in Centrally Confirmed Androgen Receptor Positive (AR+) Subjects.

2. Clinical Question

In statistical terms, this is a single-arm estimation question: the endpoint describes outcomes within the treated group, rather than a treatment contrast between groups. That distinction is central to interpretation. An observed clinical benefit rate, if available, would describe the proportion meeting the stated response-or-stability definition in the specified population and timeframe. Without a concurrent control group, it would not by itself establish how outcomes would have differed under another treatment or under no treatment.

The registry gives the study’s purpose as determining whether GTx-024 is effective and safe in this patient population. That stated purpose is not itself a finding. The primary outcome value, its uncertainty, and the analysis details needed to assess it are not reported in the registry record.

3. Trial Design

The registry describes a phase 2, open-label, multicenter, multinational study of GTx-024 in advanced AR+ triple negative breast cancer. It is classified as a single-group study. Allocation is recorded as NA and masking as none; there is no randomized comparator arm described. The registry reports an enrollment of 32. It does not clarify in the listed information whether that enrollment figure represents a planned or completed count.

The intervention was GTx-024 capsules, 18 mg PO once daily for up to 12 months. The primary endpoint was clinical benefit at sixteen weeks among subjects whose AR+ status was centrally confirmed. The clinical benefit definition included complete response, partial response, or stable disease, assessed by CT or MRI under RECIST v 1.1.

The record lists a study start of 2015-06 and primary completion of 2017-09-22. Its current status is terminated. The reason for termination and whether termination affected enrollment, follow-up, or outcome collection are not reported in the registry record. The record does not give further operational detail about sites, recruitment, treatment discontinuation, or follow-up procedures.

Six secondary outcome types are named: clinical benefit rate in the Full Analysis Set, best overall response, progression-free survival, time-to-progression, duration of response, and objective response rate. The registry lists eight outcome measures overall, but the listed information does not supply results for those secondary outcomes. It also records zero analyses. The analysis methods, including any adjustment for baseline characteristics or handling of time-to-event censoring, are not reported in the registry record.

Because the study has one group and no masking, it can describe outcomes observed during treatment but does not provide a randomized treatment-effect estimate. The design details also do not establish why the study was terminated or whether its planned objectives were completed.

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.

Before assignment: No patients were excluded from the study before drug assignment

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Subjects who were centrally confirmed as AR+

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.

6. Primary Endpoint

The registry lists the primary outcome as Clinical Benefit Rate, in Centrally Confirmed Androgen Receptor Positive (AR+) Subjects, measured over Sixteen (16) weeks.

The primary endpoint is the clinical benefit rate in participants with centrally confirmed AR+ status, assessed at sixteen weeks. It is defined as the count of participants with complete response, partial response, or stable disease according to RECIST v 1.1. Tumour status was assessed by CT or MRI. The registry describes complete response as disappearance of all target lesions, partial response as a >=30% decrease in the sum of the longest diameter of target lesions, and stable disease as a <30% decrease in that sum.

This endpoint groups several categories of disease status into a single measure. It is used to capture not only complete or partial tumour response, but also disease that meets the stated stable-disease criterion at the assessment time. As a general statistical point, a composite endpoint can provide a broader summary of outcomes than a response-only measure, but its interpretation depends on the component definitions and assessment schedule. The component counts can matter because the same overall clinical benefit rate could arise from different mixes of complete response, partial response, and stable disease.

The primary endpoint is described as a count of participants, while the outcome name is a rate. A rate estimate would require the number meeting the clinical-benefit definition and a defined analysis denominator. The registry record does not report the endpoint count, denominator used in its analysis, estimated rate, confidence interval, or component breakdown. Consequently, the endpoint definition is available, but its observed result and precision are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies this as a single-group study. In a single-group design, the main outcome is summarized among participants receiving the study intervention. There is no randomized control group against which to estimate a difference in outcomes. General statistical interpretation therefore focuses on the observed outcome within the studied group, the population to which it applies, the method used to calculate it, and the uncertainty around it. The registry does not report a primary endpoint estimate or its uncertainty.

What does a clinical benefit rate represent?

The endpoint definition combines complete response, partial response, and stable disease. A rate is generally calculated by relating the number of participants meeting a defined outcome to an analysis denominator. For this endpoint, interpretation depends on how the response categories are assessed and which participants are included in that denominator. The registry identifies the primary population as subjects centrally confirmed as AR+, and identifies the endpoint assessment time as sixteen weeks. It does not report the analyzed count, denominator, estimate, or confidence interval.

As a general concept, a confidence interval expresses the statistical uncertainty around an estimate under the assumptions of the analysis. It can help readers distinguish an estimate that is relatively precise from one with substantial uncertainty. It does not remove design limitations, such as the absence of a comparator, and it does not account automatically for every possible source of bias. No confidence interval for the primary outcome is reported in the registry record.

Why does the single-group design matter?

A randomized comparison aims to make groups comparable, on average, for both measured and unmeasured factors through random allocation. This record does not describe that design: it identifies one group, allocation NA, and no masking. A result within the GTx-024 group would thus be descriptive of that group and would not supply a randomized contrast. General statistical methods cannot reconstruct a concurrent control outcome that was not observed.

Open-label status means masking was absent. As a general matter, lack of masking can affect outcome assessment or care, particularly when outcomes involve judgment. Here, the primary endpoint uses response categories assessed with imaging, but the registry does not describe independent review procedures beyond the stated central confirmation of AR+ status. It does not report whether imaging response assessments were centrally reviewed or whether assessors were blinded. Those methods are not reported in the registry record.

What can be learned from the listed analysis information?

The registry records zero analyses and does not give statistical methods for the primary endpoint. It does not report a confidence-interval method, an inferential model, a prespecified threshold for interpreting the endpoint, or a hypothesis test. These omissions mean that a reader cannot determine from the registry record how the sponsor intended to quantify uncertainty or make formal statistical claims about clinical benefit.

The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. Such assumptions describe a planning exercise rather than the design actually recorded for this single-group study. In particular, the equal-allocation, two-arm framework does not describe the study’s single-group allocation. The registry record does not give the trial’s own sample-size justification, and the listed information does not provide the planning illustration’s calculated sample sizes or the observed effect on which it is based.

As a general concept, sample-size planning asks how many participants would be needed under chosen assumptions to detect an effect at a specified error level and power. Its output depends on those assumptions, including the effect size, outcome variability, allocation, and analysis method. A planning calculation is not observed power and does not establish the precision of a trial’s actual result. No trial-specific sample-size rationale is reported in the registry record.

How should the safety counts be understood statistically?

The registry’s safety summaries are counts of participants with an event. A count does not itself provide an event rate unless the relevant population and observation period are clear, and it does not show whether a participant experienced more than one event. The record lists 32 at risk for the GTx-024 group for the serious and other adverse-event summaries; the listed counts are 5 with serious events and 28 with other events. Deaths are listed as 13. The registry does not report the relation of these categories to one another, event timing, exposure-adjusted rates, or causality assessments.

General statistical interpretation of adverse events also depends on how events were defined, collected, graded, and attributed, as well as the time participants were followed. Those details are not reported in the registry record. Since there is no concurrent control group described, these safety summaries do not permit a randomized comparison of adverse-event frequency between treatments.

Finally, the status is terminated, but no reason or analysis consequences are described. A terminated status alone does not establish that the study stopped early for a particular safety or efficacy reason. Without the termination reason, participant flow, analysis populations, and outcome results, those explanations should not be inferred.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("GTx-024")
n      <- c(18)
events <- c(1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  GTx-024  18  1  5.6  0.1  27.3  1.0  25.8  1.3  26.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists eight outcome measures overall. The primary outcome is clinical benefit rate in centrally confirmed AR+ subjects. Named secondary outcomes include clinical benefit rate in the Full Analysis Set, best overall response, progression-free survival, time-to-progression, duration of response, and objective response rate. The listed information does not describe a hierarchy among the outcomes, identify which secondary outcomes were confirmatory, or report any adjustment for multiple testing.

As a general statistical issue, examining multiple outcomes can increase the chance of a seemingly notable result arising by chance when each is tested separately. A prespecified hierarchy or multiplicity adjustment can address some of that concern. The registry record does not report whether such procedures were planned or used. It records zero analyses and does not provide outcome-specific estimates or tests, so no multiplicity-adjusted interpretation can be assessed.

The primary population is described as subjects centrally confirmed as AR+, while one secondary outcome is explicitly named for the Full Analysis Set. The registry record does not define that set or state its size. It also does not report a participant disposition summary, endpoint evaluability, or which population was used for each other outcome.

Missing-data methods are not reported in the registry record. There is no description of how missing imaging assessments, withdrawals, or other unavailable outcome data were handled, nor whether any sensitivity analyses were planned. These details matter because the analysis denominator and assumptions about missing outcomes can affect an estimated clinical benefit rate. The registry does not provide enough information to determine their impact.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: chf (3.1%), pleural effusion (3.1%), pulmonary embolism (3.1%), tumor flare (3.1%), uti (3.1%).

For the GTx-024 group, the registry lists 32 participants at risk for the adverse-event summaries. It reports 5 participants with a serious adverse event and 28 with other adverse events, with the outcome data characterized as participants with an event (counts). Deaths are listed as 13. The record does not explain whether the death count overlaps with the adverse-event categories or establish a causal relationship between deaths and treatment.

The serious adverse event terms listed include CHF, pleural effusion, pulmonary embolism, tumor flare, UTI, and dehydration; each is shown with 3.1%. The record does not give event-specific counts alongside those percentages in the listed information, or explain the method used to select the terms shown. The terms and percentages should be read as the registry’s reported serious-event summary, not as evidence that GTx-024 caused those conditions.

As a general statistical point, adverse-event counts are affected by the definition and collection of events, participants’ time at risk, and follow-up completeness. Those details are not reported in the registry record. With no concurrent comparator group described, these figures cannot establish how safety outcomes compare with another treatment.

13. What the Result Does, and Does Not, Mean

The record establishes that a phase 2, open-label, single-group study evaluated GTx-024 in advanced AR+ triple negative breast cancer. It specifies a once-daily oral dose of 18 mg for up to 12 months and defines a primary clinical-benefit endpoint at sixteen weeks. It also lists selected safety counts and secondary outcome types.

It does not report the primary endpoint result. Consequently, there is no registry-reported clinical benefit rate, count meeting the endpoint, confidence interval, or primary statistical test to interpret. The absence of those results is not evidence that the endpoint was met, nor evidence that it was not met. It also does not justify a conclusion about the magnitude or precision of any treatment effect.

Even if a within-group clinical benefit estimate were available, its meaning would be limited by the lack of a concurrent randomized comparator. An outcome observed during treatment is not equivalent to an estimate of how outcomes changed because of treatment. The design cannot directly distinguish treatment effects from the natural course of disease, patient selection, other care, or other influences. This is a general limitation of a single-group study and not a claim that any particular factor explains the outcomes in this trial.

The endpoint itself combines complete response, partial response, and stable disease. A composite value would not, without the component results, describe the distribution across those categories. The listed secondary endpoints could add context, but their results are not reported in the registry record.

The safety counts should likewise be treated as descriptive. They do not establish causality or comparative safety, and the record does not supply the event collection and follow-up details needed for a fuller assessment. The terminated status does not explain why the study ended. Taken together, the available record supports a description of the study’s design and outcome definitions, but not a conclusion that GTx-024 did or did not produce clinical benefit, or a comparative benefit-risk conclusion.

14. Why This Trial Matters Statistically

This trial is statistically notable as a single-group phase 2 study whose central efficacy question was framed as estimating a clinical benefit rate at a specified assessment time. That design can generate a description of outcomes in a defined population, but it does not estimate a randomized difference between GTx-024 and a comparator. Recognizing the distinction between within-group outcomes and comparative effects is essential when interpreting treatment studies.

The endpoint also illustrates how a composite clinical outcome works. Complete response, partial response, and stable disease are combined, with imaging assessment under RECIST v 1.1. Such a measure can capture more than tumour response alone, but the interpretation depends on the definitions, assessment timing, analysis population, and breakdown of its components. The registry provides the definition and timing, but not the observed result or component counts.

The record’s limited analysis information is itself relevant. It lists outcome types and a terminated status, but does not report efficacy estimates, statistical tests, confidence intervals, missing-data procedures, or multiplicity handling. Those omissions prevent evaluation of the strength and precision of any efficacy finding. They also make clear why a registered endpoint definition should not be mistaken for a reported result.

Finally, the safety summary demonstrates the difference between event counts and causal conclusions. Counts can describe reported events, but interpreting them requires context such as exposure time, event definitions, and attribution; a comparison also requires an appropriate control. These details are not reported in the registry record. The record therefore highlights several core principles in biostatistics: design determines which comparisons are possible, endpoint definitions determine what is counted, and transparent analysis and uncertainty reporting are necessary for judging results.

15. 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.

Several trial-specific limitations restrict interpretation of the registry record. The study is classified as single group, with allocation NA and no masking, and no concurrent comparator is described. Its design therefore cannot provide a randomized estimate of how outcomes differ under GTx-024 versus another treatment.

The primary clinical-benefit result is not reported in the registry record. Neither the count meeting the endpoint nor an estimated rate, confidence interval, or component breakdown is available. The record also does not provide the analysis denominator or explain whether all participants with centrally confirmed AR+ status had evaluable imaging at sixteen weeks.

Although enrollment is listed as 32, the information does not specify the primary analysis population’s size or describe participant flow. The reason for the terminated status is not reported. It is therefore not possible to determine from the registry record whether termination affected recruitment, treatment exposure, follow-up, or outcome availability.

The registry names secondary endpoints but does not report their results or analysis methods. It does not describe how missing assessments were handled, whether outcomes were reviewed centrally, how time-to-event endpoints were analyzed, or whether multiplicity procedures were used. These details are not reported in the registry record.

The safety summary gives counts and serious-event terms, but the record does not provide event timing, duration of observation, severity grading, causality assessment, or exposure-adjusted summaries. The relationship between the listed deaths and adverse-event categories is also not reported. These limitations make the safety information descriptive rather than comparative or causal.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Efficacy and Safety of GTx-024 in Patients With Androgen Receptor-Positive Triple Negative Breast Cancer (AR+ TNBC) — NCT02368691.
• Registry record last updated 2020-11-18; status last verified 2020-10.
• Results first posted 2020-10-30.
• 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.

19. Record Summary

NCT02368691 is a phase 2, open-label, multicenter, multinational, single-group study of GTx-024 in advanced androgen receptor-positive triple negative breast cancer. The registry reports enrollment of 32, a study start of 2015-06, primary completion on 2017-09-22, and terminated status. The reason for termination is not reported in the registry record.

Participants received GTx-024 capsules, 18 mg PO once daily for up to 12 months. The primary endpoint was clinical benefit at sixteen weeks among centrally confirmed AR+ subjects, defined as complete response, partial response, or stable disease under RECIST v 1.1. The primary outcome result and its statistical uncertainty are not reported in the registry record.

The record lists secondary response and time-to-event outcomes and safety counts, including 5 participants with serious adverse events, 28 with other adverse events, and 13 deaths. The record does not establish causality for those safety outcomes. No randomized comparator is described, and the analysis methods and missing-data procedures are not reported.