A Study of Abemaciclib in Indian Women With Advanced Breast Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Abemaciclib in Indian Women With Advanced Breast Cancer (NCT04707196), a na phase 4 study. The primary outcome is Percentage of Participants Experiencing at Least One Treatment-Emergent Adverse Event.

2. Clinical Question

The study concerns safety and tolerability in a defined population and treatment setting. It does not pose a controlled efficacy question: the record describes a single-group study and does not identify a control treatment or a randomized allocation. Although participants are listed under two endocrine-therapy combinations, the groups cannot be treated as randomized arms for a causal comparison.

The record lists a secondary outcome concerning the percentage of participants who discontinued study treatment due to adverse events. Its numerical result is not reported in the registry record. The primary endpoint's numerical percentage is also not reported in the registry record. Consequently, the posted material does not establish the observed frequency for the primary endpoint, nor does it provide an estimate of treatment effect relative to a control group.

3. Trial Design

This is a Phase 4, single-group study sponsored by Eli Lilly and Company. Its title identifies abemaciclib combined with endocrine therapy in Indian women with advanced breast cancer. The registry status is completed. The listed study start is 2021-02-22 and the primary completion date is 2023-01-09. Registry enrollment is 200.

Eligible participants were described as women living in India with hormone receptor positive, human epidermal growth factor receptor 2 negative locally advanced and/or metastatic breast cancer. The brief summary says each participant's study could last up to eight months and could include up to eight visits to the study center. The primary endpoint timeframe is stated separately as baseline until the end of follow-up, up to 7 months.

The treatment group description specifies abemaciclib at 150 milligram orally twice daily on days 1 through 28 of a 28-day cycle, for up to 6 cycles, with earlier discontinuation possible for disease progression or another discontinuation criterion. The endocrine therapy could be anastrozole or letrozole, grouped as nonsteroidal aromatase inhibitors, or fulvestrant. The registry records 137 participants in the abemaciclib plus nonsteroidal aromatase inhibitor group and 63 in the abemaciclib plus fulvestrant group for the adverse-event summaries.

Allocation is listed as NA, masking as none, and the study model as single group. Therefore, the two treatment groups should not be interpreted as randomized comparators. Their membership could reflect clinical or other selection factors, which are not described in the registry record. The protocol's explanation for selecting these regimens, the specific eligibility criteria beyond the summary description, and the rationale for the enrollment target are not reported in the registry record.

The record does not report a separate comparator group or a randomized treatment assignment. That design can describe the observed safety experience among treated participants, but it cannot by itself distinguish treatment-related events from events that would have occurred for other reasons. The study's registry entry reports no analyses, and does not state an inferential analysis plan.

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 study drug.

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.

Population: All enrolled participants.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants Experiencing at Least One Treatment-Emergent Adverse Event, measured over Baseline until end of follow-up (Up To 7 Months).

The primary endpoint is the percentage of participants experiencing at least one treatment-emergent adverse event. A treatment-emergent adverse event is defined in the registry as an event that began at or after the first study medication administration, or one that began earlier but worsened after the first administration. The endpoint timeframe is baseline until the end of follow-up, up to 7 months.

The registry says this measure reflects the unique percentage of participants with any serious and other non-serious adverse events. In other words, the outcome concerns whether a participant experienced one or more qualifying events, rather than the total number of events. A participant with multiple events still contributes once to a participant-level percentage. The record directs readers to its reported adverse-events material for a summary of events regardless of causality.

This kind of endpoint is used to describe the safety experience in the treated population. A participant-level percentage is readily interpretable as the proportion of the defined population with at least one event during the stated observation period. It does not, on its own, describe the number of events per participant, the severity distribution, the timing of events, or whether an event was caused by treatment.

The numerical result for this primary endpoint is not reported in the registry record. The record identifies the measure and defines its timeframe and population, but the adverse-event counts in the registry are not a substitute for a posted primary-endpoint percentage unless the endpoint's exact numerator and denominator are reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is binary at the participant level: each person either experienced at least one qualifying treatment-emergent adverse event during the defined follow-up or did not. A percentage for such an endpoint is generally the number of participants meeting the event definition divided by the number in the endpoint population. The registry defines that population as participants who received at least one dose of study drug. The numerical endpoint result and its exact analysis denominator are not reported in the registry record, so no percentage can be stated from the primary outcome entry.

What does a participant-level percentage describe?

A participant-level percentage measures how common an event was in the observed group over the specified observation period. It differs from an event count: a participant may experience more than one event, while the “at least one” endpoint counts that participant once. The registry's definition also includes events that began before the first dose but worsened afterward. This makes the event definition broader than counting only newly started events, while still tying classification to the first administration.

The primary endpoint's stated period is baseline until the end of follow-up, up to 7 months. The brief summary separately describes a study duration of up to eight months per participant. These statements refer to different descriptions in the record and should not be silently treated as identical. The precise timing and handling of participants with shorter follow-up are not reported in the registry record. General statistical explanation: when participants have different observation times, a simple percentage can be influenced by how long each person was observed; time-to-event methods may be used when the outcome and analysis plan call for them. The record does not report a time-to-event analysis for this endpoint.

What information would quantify uncertainty?

For a binary outcome, an estimate is typically accompanied by a confidence interval. General statistical explanation: a confidence interval expresses the uncertainty associated with estimating a population percentage from a sample, conditional on the method and assumptions used. It is not a guarantee about the population value, and its width is affected by the amount of information and the observed event frequency. The registry record does not report the primary estimate, confidence interval, or method used to calculate one. Precision for this endpoint therefore cannot be evaluated from the primary outcome entry.

The posted serious and other adverse-event summaries give group denominators and counts. Those are descriptive quantities. They are not a substitute for the primary endpoint's unique participant percentage, because the record does not explicitly identify those summary counts as the primary endpoint numerator or provide its overall endpoint calculation. The terms listed for serious events are also descriptive. Their listed percentages do not constitute adjusted estimates or tests of differences between treatment groups.

Why is this not a comparative treatment analysis?

The registry identifies a single-group model and allocation as NA, with no masking. The two recorded treatment groups received abemaciclib with different endocrine therapy options, but the registry does not describe random assignment between those options. General statistical explanation: randomization is used to balance measured and unmeasured prognostic factors on average, supporting a more credible causal comparison. Without randomized allocation or an appropriate adjustment strategy, observed differences between groups may reflect who received each regimen or other factors, rather than a treatment effect.

The record lists zero analyses. It does not report a model, hypothesis test, confidence interval, adjustment strategy, or prespecified comparison. The statistical plan, including any plan for interim analyses, is not reported in the registry record. No test of a difference between the two regimen groups should be inferred from the adverse-event counts alone.

How should planning calculations be understood?

The planning illustration is described as a calculation from an observed effect rather than the trial's own design. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event outcomes, the illustration is described in total events, and for other outcomes it is described in participants per arm. These are planning assumptions, not evidence that the study used those assumptions to set enrollment.

General statistical explanation: a sample-size planning calculation asks how much information a future or hypothetical design would need for a specified target effect and statistical assumptions. It does not report what the trial observed, and it does not establish the probability that the trial's result is correct. Planning values are not observed power. The registry record does not report the trial's own sample-size justification, and the planned enrollment of 200 should not be treated as proof that the primary endpoint was estimated with a particular precision.

General statistical explanation: over-dispersion is relevant when count data vary more than a chosen model expects, potentially making standard errors too small if the model is not appropriate. It is not a direct explanation for a participant-level binary endpoint, and the registry does not report a model for which over-dispersion was assessed. There is no basis in the record to claim that a particular modeling method, correction, or diagnostic was used.

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("Abemaciclib + NSAI", "Abemaciclib + Fulvestrant")
n      <- c(137, 63)
events <- c(107, 44)
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  Abemaciclib + NSAI  137  107  78.1  70.2  84.7  70.5  84.2  70.4  84.2
ARM  Abemaciclib + Fulvestrant  63  44  69.8  57.0  80.8  57.6  79.8  57.6  79.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and identifies a primary safety outcome and a secondary outcome concerning discontinuation from study treatment due to adverse events. It does not report numerical results for either measure in the information available for these outcomes. The record lists zero analyses and does not report a statistical analysis plan describing how outcomes were tested or summarized.

Multiplicity arises when several outcomes, time points, subgroups, or comparisons are evaluated. General statistical explanation: evaluating many statistical questions can increase the chance of at least one apparently unusual result, so a prespecified strategy may define which outcome is primary and whether any adjustment or hierarchy is used. The record identifies a primary endpoint, but does not report a multiplicity strategy, the number of planned statistical tests, or whether any adjustment was intended. No adjustment should be assumed.

The primary endpoint population is described as participants who received at least one dose of study drug. This is a treated population definition, not an intention-to-treat population definition. The record does not report a separate intention-to-treat analysis, per-protocol analysis, or other analysis population. It does not report how participants who discontinued early, lacked follow-up, or had missing adverse-event information were handled.

Missing-data methods, reasons for missingness, completeness of follow-up, and any imputation approach are not reported in the registry record. General statistical explanation: missing outcome information can affect a percentage if the likelihood of missingness is related to participant characteristics or event experience. Without information about missingness and its handling, readers cannot assess whether the reported group summaries, where available, represent all participants in the defined endpoint population.

The enrollment total and the group denominators in the adverse-event summaries are recorded, but a participant flow accounting for the difference is not reported. The exact relationship between enrollment, treatment receipt, and inclusion in each endpoint analysis is therefore not fully described.

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: thrombocytopenia (1.6%), cardiac failure congestive (1.6%), multiple organ dysfunction syndrome (1.6%), covid-19 pneumonia (1.6%), neutropenic sepsis (1.6%).

The adverse-event summary records serious adverse events for 9 of 137 participants receiving abemaciclib plus a nonsteroidal aromatase inhibitor and for 5 of 63 receiving abemaciclib plus fulvestrant. Other adverse events are recorded for 105 of 137 and 44 of 63 participants, respectively. These are group-specific counts and denominators as recorded in the registry. They should not be read as a controlled comparison because the study is single-group and the regimen groups were not described as randomized.

The record lists deaths as 3 in the nonsteroidal aromatase inhibitor group and 1 in the fulvestrant group. The registry information does not state that these deaths were caused by study treatment. The counts do not establish causality, and should not be combined into a treatment-effect claim.

Six serious adverse-event terms are each listed at 1.6%: thrombocytopenia, cardiac failure congestive, multiple organ dysfunction syndrome, Covid-19 pneumonia, neutropenic sepsis, and urinary tract infection pseudomonal. These entries are descriptive safety information. The posted details do not establish an individual participant's full clinical course or attribution for each event.

The primary endpoint is a unique participant percentage for at least one treatment-emergent event, while the serious and other event summaries are separately reported safety figures. The primary endpoint's numerical percentage is not reported in the registry record, so the group summaries should not be substituted for it.

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

The study record describes the safety experience of participants receiving abemaciclib in combination with endocrine therapy in India. It identifies the primary endpoint, its event definition, its follow-up period, and the treated population. It also gives counts for serious and other adverse events by the two recorded regimen groups. Those details provide a descriptive account of what the registry reports.

The record does not report the numerical result for the primary endpoint, the result for discontinuation due to adverse events, or an inferential analysis. It does not provide a primary estimate with a confidence interval. Therefore, the registry entry does not permit a reader to quantify the primary event percentage or its statistical precision from the information reported for that endpoint.

The two treatment groups are not randomized controls. Differences in their adverse-event counts cannot be interpreted as causal differences between nonsteroidal aromatase inhibitor and fulvestrant combinations. There is no untreated group or alternative-treatment comparator described. The record likewise does not establish that any particular adverse event or death was caused by study treatment.

General statistical interpretation: a descriptive safety summary can characterize events observed among treated participants, but separating treatment effects from background illness, other care, or differences between participants requires an appropriate comparative design and analysis. The registry information does not report such an analysis. Its adverse-event figures should be understood within those limits.

The registry describes this as a Phase 4 study and reports completion, but those labels do not supply missing endpoint results. Nor does an enrollment figure establish that an endpoint was adequately precise. The record does not report the trial's sample-size justification, missing-data handling, or statistical plan. The central supported reading is consequently limited: the study was conducted in the stated population and treatment setting, and the posted safety counts describe the recorded groups, while the primary endpoint result and comparative conclusions remain unavailable in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a registered safety question and the information reported as its result. The registry defines a participant-level primary outcome, a timeframe, and an analysis population, but the numerical primary outcome is not reported in the registry record. That distinction matters because a clearly specified endpoint does not itself communicate the observed event frequency or the uncertainty around it.

The single-group model also shapes what can be learned. The study can describe adverse events among participants who received the combination regimens, but it does not include a randomized control group. The two regimen groups should not be mistaken for a controlled comparison. This is important when readers encounter separate counts or listed event percentages: differences may be descriptive, but the record does not support attributing them to the endocrine treatment choice.

The registry gives group-specific serious and other adverse-event counts and records deaths. Those figures are useful as safety descriptions, but they do not replace the primary endpoint result, and they do not establish causation. A sound interpretation keeps distinct the event definitions, denominators, timeframe, and causal questions each type of statistic can address.

Finally, the record illustrates why statistical transparency includes more than a planned enrollment number. The analysis plan, sample-size justification, missing-data handling, and inferential results are not reported in the registry record. Without these details, readers cannot assess the intended estimation strategy or the precision of the main safety measure. The design and posted counts can be described, but the strength and limitations of any treatment-effect conclusion cannot be evaluated because the record does not report one.

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 main limitation for statistical interpretation is that the primary endpoint's numerical result is not reported in the registry record. No confidence interval or inferential analysis is reported, and the record lists zero analyses. The secondary endpoint concerning treatment discontinuation due to adverse events is identified, but its result is not reported in the registry record either.

The study is single-group, with allocation listed as NA and masking as none. Although safety counts are presented for the abemaciclib plus nonsteroidal aromatase inhibitor and abemaciclib plus fulvestrant groups, the registry does not describe randomized assignment. These groups therefore do not form a like-for-like control comparison, and their counts cannot establish comparative safety or a causal effect.

The registry does not report the protocol's sample-size justification, planned statistical methods, interim analyses, multiplicity strategy, confidence-interval method, missing-data approach, or analysis populations beyond the primary endpoint's treated-participant definition. It also does not give a participant-flow account explaining the relationship between enrollment and the adverse-event denominators. These omissions limit assessment of selection, follow-up completeness, precision, and the intended analysis.

The timeframe description for the primary endpoint is up to 7 months, while the brief summary describes study participation as up to eight months. The registry does not explain the relationship between these descriptions or how differing observation times were handled. The safety figures alone do not establish event causality, and the death counts do not identify treatment attribution. These limitations constrain conclusions to a descriptive reading of the recorded safety information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Abemaciclib in Indian Women With Advanced Breast Cancer — NCT04707196.
• Registry record last updated 2023-11-24; status last verified 2023-11.
• Results first posted 2023-11-21.
• 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.

19. Record Summary

NCT04707196 is a completed Phase 4, single-group study of abemaciclib with endocrine therapy in Indian women with hormone receptor positive, human epidermal growth factor receptor 2 negative locally advanced and/or metastatic breast cancer. Registry enrollment is 200. The listed study start is 2021-02-22, and the primary completion date is 2023-01-09.

The primary endpoint is the percentage of participants experiencing at least one treatment-emergent adverse event from baseline until the end of follow-up, up to 7 months. Its numerical result is not reported in the registry record. The adverse-event summaries record serious and other event counts for the abemaciclib plus nonsteroidal aromatase inhibitor and abemaciclib plus fulvestrant groups, but the groups are not randomized controls. The registry lists zero analyses and does not report the sample-size justification, statistical plan, or missing-data methods. The record supports a descriptive account of the posted safety information, not a controlled estimate of treatment effect.