LY3023414 and Prexasertib in Metastatic Triple-negative Breast Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for LY3023414 and Prexasertib in Metastatic Triple-negative Breast Cancer (NCT04032080), a na phase 2 study. The primary outcome is Efficacy (Objective Response Rate).

2. Clinical Question

The study asks whether this treatment combination is associated with the defined clinical-benefit outcome in this patient population. Its primary endpoint is not described as a comparison against another treatment or against a control group. Consequently, even a reported response proportion would describe outcomes among treated participants; by itself, it would not establish how those outcomes compare with another approach.

The registry lists duration of response as a secondary efficacy outcome, but does not report a result for it. It also does not report the number of participants who met the primary endpoint. The clinical question can therefore be identified from the protocol description, but its answer cannot be estimated from the posted primary-outcome information.

3. Trial Design

This was a phase 2, completed, single-group clinical trial sponsored by Baylor Research Institute. The registry lists an enrollment of 10 and describes the condition as triple-negative breast cancer. The official title specifies chemotherapy-pretreated metastatic triple-negative breast cancer, and the treatment arm is described as patients with metastatic disease who met the enrollment criteria.

Participants received LY3023414 plus prexasertib. The arm description says treatment continued until disease progression. The primary-outcome population is defined as all participants who received at least one dose of treatment. The number in that population is not reported in the registry record, so the enrollment figure should not be treated as the denominator for the primary endpoint without further information.

The trial is listed as unmasked, with allocation recorded as not applicable and a single-group model. It is not a randomized comparison, and the combination arm has no concurrent control arm. The registry lists a start date of 2019-09-05, a primary completion date of 2022-06-01, and an overall status of completed. Its primary outcome is objective response rate, defined using prolonged clinical benefit; duration of response is listed as a secondary outcome.

The design can describe outcomes observed while participants received the combination, but cannot directly separate treatment effects from other explanations for those outcomes. The registry record does not report a detailed statistical analysis plan, sample-size justification, interim-analysis plan, or comparative treatment estimate.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All participants who received at least one dose of treatment.

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 Efficacy (Objective Response Rate), measured over Through study completion, approximately 2 years and 8 months.

The primary endpoint is titled efficacy (objective response rate) and is measured in participants. Its registry definition is specific: objective response is measured as prolonged clinical benefit, and clinical benefit is defined as progression-free survival on study therapy for at least 6 months. Thus, the outcome is not simply labeled as a tumor-shrinkage measure in the registry description; it uses a time-on-treatment progression criterion.

A response-rate endpoint is generally used to describe the fraction of participants who meet a prespecified response definition. It can provide a concise summary of whether participants met that criterion, while the definition determines exactly what counts as a response. In this trial, the stated criterion combines remaining progression-free with a duration threshold. The registry gives the assessment timeframe as through study completion, approximately 2 years and 8 months.

The outcome population is all participants who received at least one dose. The registry record does not report the number who met the endpoint, the corresponding response proportion, or an uncertainty interval. It is therefore possible to explain the endpoint's intended meaning, but not to estimate the observed response rate from the posted primary-outcome information. Duration of response is listed separately as a secondary outcome, with no result reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of endpoint is this?

The primary endpoint is a binary participant-level outcome: a participant either meets the stated clinical-benefit definition or does not. The definition requires progression-free survival on study therapy for at least 6 months. The registry labels the endpoint objective response rate, but its description specifies this prolonged-benefit criterion. Interpretation should follow the definition, rather than assuming that the label alone identifies the precise assessment rule.

For a binary endpoint, the basic descriptive result is a count of participants meeting the definition together with a denominator and a proportion. These quantities answer different parts of the question: the count records how many participants met the criterion, the denominator identifies the population assessed, and the proportion expresses the count relative to that population. The registry record specifies an intended population of participants who received at least one dose, but does not report the endpoint count, denominator, or proportion.

How does a single-group design affect interpretation?

A single-group study observes outcomes in participants receiving the study treatment without a concurrent control arm. Its direct statistical description is therefore within-group: what outcomes were recorded among the treated participants. It does not directly estimate a between-group treatment contrast. In general, a treatment contrast requires outcomes under the study treatment and a suitable comparator, along with an analysis that addresses how the groups were formed.

Here, allocation is recorded as not applicable and the model as single group. The trial is also listed as unmasked. These design features do not make a descriptive outcome meaningless, but they constrain causal interpretation. Factors other than treatment, including differences in participant characteristics or the course of disease, may contribute to observed outcomes. The registry record does not report an analysis that could quantify or remove those influences.

What would an uncertainty interval convey?

In general, a confidence interval expresses uncertainty around an estimated quantity under the assumptions of the statistical method used. For a response proportion, it helps readers judge how precisely the data locate the underlying response rate. It does not guarantee that the true value lies within a particular interval, and it cannot correct weaknesses in the design or outcome definition.

No primary response estimate or interval is reported in the registry record. As a result, the precision of the primary outcome cannot be evaluated. The enrolled number alone cannot supply that missing information: the outcome denominator and the count meeting the definition are also needed.

What do the sample-size illustrations mean?

The stated sample-size illustration is a planning exercise based on the observed effect, not the trial's own design justification and not observed power. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes detecting a stated fraction of the observed effect. For time-to-event outcomes, the stated convention is to give the total number of events; for other outcomes, it is participants per arm.

Those assumptions describe a hypothetical two-arm planning setup, whereas this trial is single group. They should not be read as a description of the actual allocation or as evidence that this trial had a particular probability of detecting an effect. The registry record does not report the trial's sample-size justification or statistical design assumptions. A sample-size illustration is not a substitute for the observed endpoint estimate, its uncertainty, or a prespecified analysis.

Why does over-dispersion matter in general?

Over-dispersion is a general issue in count-data modeling: observed variability may exceed what a model's assumed distribution allows. If a model ignores that extra variability, uncertainty can be understated and statistical conclusions can appear more precise than warranted. This concept is not a reported feature of this trial's primary endpoint, which is described as a participant-level binary outcome. The registry record does not report a count-model analysis or an over-dispersion assessment.

What analyses are actually reported?

The registry record contains no analysis entries for the listed outcomes. It does not report a primary response estimate, a confidence interval, a hypothesis test, or a detailed analysis method. The endpoint definition and population are available, but the statistical result needed to evaluate efficacy is not. General explanations of proportions, intervals, and design limitations clarify how such results would ordinarily be interpreted; they should not be mistaken for analyses reported for this trial.

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("LY3023414 + Prexasertib")
n      <- c(10)
events <- c(3)
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  LY3023414 + Prexasertib  10  3  30.0  6.7  65.2  10.8  60.3  10.9  61.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists objective response rate as the primary outcome and duration of response as a secondary outcome. It reports two outcome measures, but the registry record contains no analysis entries. It does not describe a multiplicity adjustment, a hierarchy for testing outcomes, or another procedure for controlling the interpretation of multiple statistical tests. Whether any such procedure was prespecified is not reported in the registry record.

Missing-data handling is also not reported. The endpoint population is defined as participants who received at least one dose, but the record does not explain how participants with missing assessments, early discontinuation, or unavailable progression information were treated in the endpoint analysis. These details matter because a binary response proportion depends on how the analysis population and unevaluable outcomes are handled. No imputation or sensitivity-analysis approach is reported.

The analysis population is described for the primary endpoint, but the number included in that population is not reported. The record does not state that an intention-to-treat analysis was used, and that label should not be inferred from enrollment. Nor does it report a separate safety analysis population beyond the adverse-event group counts. The counts at risk are shown for that group, but the registry does not explain whether they correspond to all enrolled participants or another defined population.

These omissions limit reproducibility and make it difficult to assess how robust an endpoint estimate would be to missing observations or alternative analysis choices. The record's absence of reported methods does not establish that no methods were used; those methods are simply not reported in the registry record.

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: neutrophil count decrease (10.0%), pleural effusion (10.0%), febrile neutropenia (10.0%).

The adverse-event record lists one group, LY3023414 + Prexasertib, with 10 participants at risk for serious adverse events and 3 participants affected. It also lists 10 participants at risk for other adverse events and 10 affected. The record reports 8 deaths. The top serious-event terms are neutrophil count decrease, pleural effusion, and febrile neutropenia, each listed at 10.0%.

These are descriptive counts and percentages. They do not establish that an event was caused by treatment. The registry record does not report event timing, the relationship of events to treatment, causes of death, or participant-level overlap among event categories. A participant may contribute to more than one event term, so the listed terms should not be added to obtain a total number of affected participants. The serious-event counts and the primary efficacy endpoint answer different questions; neither can be used as a substitute for the other.

The record does not provide further detail about event severity beyond the serious-event classification, duration, resolution, or exposure time. The figures therefore describe what was recorded in the registry, while leaving important context for individual and comparative safety interpretation unreported.

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

The posted information establishes the trial's design, treatment, endpoint definition, and selected safety counts. It does not establish the observed primary response rate: the registry record gives no count meeting the clinical-benefit definition and no corresponding proportion or uncertainty interval. The appropriate statistical conclusion is that the primary efficacy result cannot be evaluated from the outcome information reported in the registry record.

Even if a single-group response proportion were available, it would describe participants treated with LY3023414 plus prexasertib rather than a treatment difference against a concurrent control. The study design cannot directly show what would have happened to comparable participants under a different treatment. Accordingly, the design alone cannot demonstrate that the combination caused a response or improved outcomes relative to another option.

The safety counts are also descriptive. The record reports serious adverse events, other adverse events, and deaths, but does not provide attribution or detail sufficient to determine their causes. These values should not be converted into claims about treatment effect or treatment-related risk without the missing context.

The registry's completed status indicates that the study is recorded as completed; it does not fill the gap in the posted primary-outcome result. Likewise, enrollment is not a measure of efficacy and does not by itself establish the precision of an outcome estimate. The most defensible reading is therefore bounded: the record describes a small single-group phase 2 trial and its planned endpoint, but does not report the primary result needed to answer the efficacy question.

These limitations do not show that the combination did or did not produce clinical benefit. They identify what can and cannot be concluded statistically from the registry record: design and safety descriptions are available, while the primary efficacy estimate and its precision are not reported.

14. Why This Trial Matters Statistically

This trial illustrates how an endpoint's operational definition shapes its interpretation. The primary outcome is titled objective response rate, but the registry defines response through prolonged clinical benefit, specifically progression-free survival on study therapy for at least 6 months. Readers need that definition to understand what a reported response count would represent; the endpoint label alone would not be enough.

The design also highlights the distinction between describing an outcome and estimating a treatment contrast. A single-group study can report what occurred among treated participants, but it does not provide a concurrent comparison. That distinction is important when moving from an observed outcome to a causal claim. Statistical methods cannot create a randomized comparator where the design did not include one.

Another important lesson is that enrollment is not interchangeable with the analysis denominator. The primary population is specified as participants who received at least one dose, while the number in that population and the number meeting the endpoint are not reported. Without those elements, neither the response proportion nor its precision can be assessed.

The registry record also separates what is known from what remains unreported. It gives selected adverse-event counts, but not the context needed to interpret causality; it names a primary and secondary outcome, but gives no analysis entries. This is a useful reminder that a trial's status and design description are not substitutes for outcome results or a statistical analysis plan.

Finally, planning calculations should not be confused with observed evidence. An illustration based on a hypothetical two-arm design does not change the fact that this study is listed as single group, nor does it establish observed power. Keeping design, endpoint, analysis population, and result distinct is essential for a sound statistical reading.

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.

The absence of a reported primary endpoint result is the central limitation for evaluating efficacy. The registry record does not give the number meeting the prolonged clinical-benefit definition, the analysis denominator, a response proportion, or an uncertainty interval. It also contains no analysis entries, so the statistical method used for the primary outcome cannot be checked against the endpoint description.

The single-group design has no concurrent comparator. Any outcome estimate, if reported, would be descriptive of the treated participants and could not directly quantify a difference from another treatment. The record also lists the trial as unmasked. It does not describe procedures to limit assessment bias or provide details on endpoint assessment, so those aspects cannot be evaluated from the registry record.

The enrollment is 10, but the number in the primary endpoint population is not reported. Missing-data rules, handling of unevaluable participants, and sensitivity analyses are not reported either. This leaves uncertainty about which observations would contribute to a response estimate and how incomplete assessments would affect it.

For safety, counts are available, but event attribution, timing, duration, participant-level overlap, and causes of death are not reported. The registry therefore supports description of the listed counts, not conclusions about causation. The sample-size illustration's two-arm assumptions are not the trial's single-group design, and the registry record does not state a trial-specific sample-size justification.

These limitations concern what can be interpreted from the registry record. They do not establish that analyses or additional information do not exist outside the record; those details are not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: LY3023414 and Prexasertib in Metastatic Triple-negative Breast Cancer — NCT04032080.
• Registry record last updated 2026-10-27; status last verified 2026-10.
• Results first posted 2023-09-11.
• 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

The registry record describes NCT04032080, a completed phase 2, unmasked, single-group study sponsored by Baylor Research Institute. It lists enrollment of 10 and evaluates LY3023414 plus prexasertib in metastatic triple-negative breast cancer. Treatment was described as continuing until disease progression.

The primary outcome is objective response rate, defined as prolonged clinical benefit, with clinical benefit specified as progression-free survival on study therapy for at least 6 months. Duration of response is listed as a secondary outcome. The primary outcome population is participants who received at least one dose.

The registry record does not report the primary response count, proportion, or an analysis. It lists serious adverse events affecting 3 participants among 10 at risk, other adverse events affecting 10 among 10 at risk, and 8 deaths. These safety figures are descriptive, and treatment attribution is not reported.