Immune Modulation by Abemaciclib in Head and Neck Squamous Cell Carcinoma (HNSCC). (AIM Trial): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Immune Modulation by Abemaciclib in Head and Neck Squamous Cell Carcinoma (HNSCC). (AIM Trial) (NCT04169074), a na phase 2 study. The primary outcome is Measure Quantitative Change in Tumor Size to Assess the Clinical Activity of Abemaciclib..

2. Clinical Question

The trial focused on a brief preoperative exposure rather than a comparison of ongoing treatment strategies. Its stated purpose was to assess clinical and biological effects of abemaciclib in HPV-negative HNSCC. The primary endpoint captured the clinical component: change in tumor size after the treatment window. A secondary outcome concerned safety and tolerability according to NCI Common Terminology Criteria for Adverse Events, version 5.

The registry describes 7 enrolled participants, while the primary outcome description states that 4 completed both required tumor measurements and were evaluable for that endpoint. The numerical estimate of tumor-size change, its standard deviation, and any confidence interval or inferential test result are not reported in the registry record. As a result, the clinical question can be described, but the magnitude and precision of the observed primary outcome cannot be determined from the posted registry information.

3. Trial Design

This was a Phase II, single-group, unmasked window trial sponsored by the University of Arizona. The registry lists an enrollment of 7 and a status of terminated. The recorded study start was 2021-07-07, and the primary completion date was 2024-12-16. The reason for termination is not reported in the registry record.

Participants received neoadjuvant abemaciclib before planned surgery. The intended exposure was a single cycle lasting 10-21 days, with up to 7 additional days allowed if surgery was delayed. The arm description refers to administration on days 1-21 and identifies oral dosing, but its dosing statement is incomplete in the registry record. A more detailed schedule beyond what is stated there should not be inferred.

Because there was no control arm, the design did not provide a randomized or concurrent comparison. The primary endpoint compared each evaluable participant’s post-treatment tumor measurement with that participant’s baseline measurement, then described change as a continuous outcome. This before-and-after structure can describe what happened during the treatment window, but it cannot by itself distinguish treatment-associated change from other explanations, including measurement variation or changes occurring over time.

The registry lists 12 outcome measures and no analysis records. That does not establish which analyses were conducted or planned; the statistical analysis plan, including any prespecified model or inferential procedure, is not reported in the registry record. The record also does not report a sample-size justification. The study’s early termination and the smaller number of participants with paired tumor measurements are important context when reading its outcome information.

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: 4 patients completed baseline and post treatment tumor measurements. Percent change in tumor size (∆T) from baseline to post-treatment were evaluated. Due to early termination, only 4 patients were evaluable; formal inference is limited and results should be interpreted descriptively.

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 Measure Quantitative Change in Tumor Size to Assess the Clinical Activity of Abemaciclib., measured over This outcome measure will be assessed at baseline and post 10-21 (+7) days of neoadjuvant exposure to abemaciclib..

The primary endpoint was quantitative change in tumor size after 10-21 days of neoadjuvant exposure, with an additional 7 days allowed for surgical delay. Tumor change was defined as percent change in RECIST v1.1 measurements for index lesions, evaluated under criteria proposed by the RECIST Committee. The endpoint was continuous, and the registry identifies the intended summary as a mean with standard deviation.

A continuous measure retains information about the size and direction of change rather than assigning each participant to a broad category. A mean describes the average change across the analyzed participants; a standard deviation describes how dispersed individual changes are around that average. These summaries can help characterize both the typical observed change and the variability in responses, but they do not alone establish a causal treatment effect.

The registry says that 4 patients completed both baseline and post-treatment tumor measurements. It does not report the mean percent change, standard deviation, individual measurements, or an uncertainty interval. Therefore, the endpoint’s definition and measurement approach are available, but its numerical result and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods can be understood by separating the endpoint’s measurement, its descriptive summary, and the type of inference the design could support. The primary endpoint was continuous: percent change in tumor size based on RECIST v1.1 metrics for index lesions. The registry identifies a mean and standard deviation as the summary statistics. It does not report a particular statistical test, model, confidence interval method, or adjustment procedure.

What does a mean summarize?

In general, a mean is the arithmetic average of the observations included in an analysis. For a continuous change measure, it gives a summary of the average direction and size of change in the analyzed group. It can be useful for a concise description, but it can also obscure variation between participants. An average is not a description of every participant’s experience, and it should be read alongside information about spread and uncertainty.

Here, the registry describes the outcome as percent change from baseline to post-treatment. It identifies 4 participants with both measurements, but the mean value is not reported in the registry record. The actual direction and size of the mean therefore cannot be interpreted. The use of the word “mean” in the endpoint definition does not itself supply an outcome estimate.

What does a standard deviation add?

In general, a standard deviation describes how much the observed values vary around their mean. A smaller spread means observations are closer to the mean; a larger spread means they are more dispersed. It is a description of variability among observations, not a measure of how precisely the mean has been estimated. Precision of the mean is usually conveyed with an uncertainty interval, such as a confidence interval, when one is reported.

The registry names standard deviation as the planned measure of dispersion but does not report its numerical value. It also does not report a confidence interval for the primary endpoint. Consequently, neither participant-level variability nor uncertainty around the average can be evaluated from the posted outcome information.

What can a before-and-after comparison establish?

In general, paired measurements compare each participant with their own baseline. This can account descriptively for starting differences between participants because the change is calculated within each person. However, a single-group before-and-after comparison does not supply the counterfactual outcome: what would have happened over the same period without the intervention. Without a concurrent comparator, the observed change cannot be separated from time effects, measurement variability, or other factors that may have changed during the treatment window.

The design was single-group, with no masking. The registry does not report an inferential procedure for the paired measurements, so it would be inappropriate to assert that a particular paired test or model was used. The endpoint’s description says that results should be interpreted descriptively and that formal inference is limited.

How should sample-size illustrations be understood?

In general, a sample-size calculation is a planning exercise about the number of participants needed for a specified design, effect, and statistical assumptions. It is not a measure of the strength of results after a study has been conducted. The registry’s stated sample-size illustration assumptions describe two-sided significance level 0.05, equal allocation between two arms, a normal approximation, and effects expressed as a fraction of the observed effect. Those are illustration assumptions, not evidence that this single-group trial used a two-arm design or that the trial had a particular power.

The registry’s assumptions say that such illustrations report participants per arm, except for time-to-event outcomes, which report total events. The trial’s primary endpoint was continuous and its design was single-group. Numerical planning-illustration results are not reported in the registry record, and no sample-size justification for the trial is reported there. Any planning illustration should therefore be kept separate from the observed study results; it cannot repair the absence of a reported primary estimate or be described as observed power.

What is known about analysis procedures?

The registry lists 12 outcome measures but no analysis records. This does not prove that no analyses were performed. It means the registry record does not present analysis records from which to identify the actual analytic population, model, handling of missing data, or inferential strategy. Those procedures are not reported in the registry record. A statistical analysis plan and details of any protocol amendments are also not reported, so the intended analysis cannot be reconstructed beyond the endpoint’s stated summaries.

These distinctions are important: an endpoint definition says what was to be measured; a descriptive statistic says how observations may be summarized; and an inferential method says how uncertainty or a hypothesis is evaluated. The record contains the first and names the intended descriptive summaries, but does not provide the numerical primary result or describe a completed inferential analysis.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Treatment With Abemaciclib")
n   <- c(4)
m   <- c(-0.01)
sp  <- c(0.16)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Treatment With Abemaciclib  4  -0.010  0.160  -0.265  0.245

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures, including the primary tumor-size measure and a secondary safety and tolerability outcome. When a study evaluates multiple outcomes, multiple time points, or multiple analyses, the chance of obtaining an apparently notable result by chance can increase if many inferential tests are performed. General approaches include identifying a primary outcome in advance, prespecifying a testing sequence, or adjusting for multiple comparisons. The registry record does not report a multiplicity strategy, and it does not provide enough analysis detail to determine whether adjustments were used.

The registry lists no analysis records. This should not be taken to mean that no statistical analyses occurred; rather, the analyses and their methods are not reported in the registry record. The primary endpoint description identifies a mean and standard deviation, but no numerical estimate, confidence interval, or p-value is reported. There is therefore no reported inferential result for which multiplicity handling can be evaluated.

Missing endpoint data are relevant because the primary outcome description identifies 4 participants with complete baseline and post-treatment measurements, while enrollment was 7. The record attributes the limited evaluable group to early termination but does not report reasons for missing measurements by participant, a missing-data method, or a sensitivity analysis. It also does not state whether the primary analysis population was defined in advance or whether any participants were excluded for other reasons.

In general, analyses restricted to participants with complete measurements can be affected if the availability of measurements is related to outcomes or participant characteristics. That possibility cannot be assessed from the record. The participant flow, analysis population definitions, and missing-data assumptions are not reported in the registry record. Accordingly, the endpoint information supports only a description of how many completed paired measurements were available; it does not establish how missing observations were handled in a final analysis.

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: myocardial infarction (14.3%), surgical and medical procedures - other, specify - flap graft failure (14.3%), thromboembolic event (14.3%), skin infection (14.3%).

The safety information is reported for the treatment group, with 7 participants at risk for both serious and other adverse events. The registry lists 2 participants affected by serious adverse events and 6 affected by other adverse events. It records zero deaths. These are group-level counts; they do not indicate how many events each affected participant experienced.

The listed serious-event terms are myocardial infarction, surgical and medical procedures—other, specified as flap graft failure, thromboembolic event, and skin infection. Each is listed at 14.3%. These are the terms and percentages recorded in the registry; the record does not report further event-level context in the information presented.

Adverse-event reporting describes events observed during the study and does not, by itself, establish that study treatment caused them. The registry record does not provide a control group for comparison. It also does not give the timing, duration, resolution, severity grading, or attribution for each listed event in the information available. The safety counts should therefore be read as descriptive observations in this small treated group, not as estimates of comparative risk or proof of causation.

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

The registry record defines a focused clinical question: whether tumor size changed over a short neoadjuvant abemaciclib window in patients with HPV-negative HNSCC. It identifies the measurement approach and states that 4 patients completed both baseline and post-treatment tumor measurements. It also reports descriptive safety counts for the treated group. These details help clarify what the study set out to measure and what information was recorded.

The record does not report the primary endpoint’s mean percent change or standard deviation. It therefore does not establish the magnitude or direction of the average tumor-size change, nor how much individual changes varied. There is also no reported confidence interval or inferential test result to indicate precision. The primary outcome description itself says that formal inference is limited and results should be interpreted descriptively.

The single-group design cannot compare outcomes with a control group, and the unmasked design does not supply blinded assessment. Even if a numerical before-and-after change were reported, it would describe change during the treatment window rather than isolate a causal treatment effect. Other influences on measurement or change over time could not be ruled out by this design alone.

Similarly, the adverse-event counts describe what was reported among participants at risk, but they do not establish that abemaciclib caused any listed event. There is no concurrent group in the record to estimate a comparative safety difference. The registry does not report the reason for termination or detailed missing-data procedures, so those aspects should not be inferred.

In short, this record supports an account of the trial’s design, outcome definition, evaluable primary-outcome group, and recorded safety counts. It does not support a quantitative conclusion about the primary tumor-size result or a causal conclusion about efficacy or safety. Those limits reflect what is not reported and the constraints of a small, terminated, single-group study.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the difference between a clearly defined endpoint and a fully reported result. The registry specifies a continuous tumor-size measure, the comparison time points, the RECIST-based approach, and the intended summaries. Yet it does not report the numerical mean or standard deviation. Readers can identify what was to be measured without being able to judge the size, direction, or precision of the result.

It also illustrates why the analysis population matters. The record lists enrollment of 7, but only 4 participants completed both measurements required for the primary endpoint. That distinction affects how broadly a descriptive result could be applied, even if the numerical estimate were available. The missing-data approach and reasons for unavailable measurements are not reported in the registry record, so the potential effect of incomplete follow-up cannot be assessed.

The single-group window design also clarifies the boundary between describing change and estimating a comparative effect. Paired measurements can characterize change over the treatment interval, but without a control group they cannot separate treatment-associated change from other concurrent influences. This is a design limitation, not a property that can be remedied by statistical wording or by a planning calculation.

Finally, the record’s safety counts and outcome list show why descriptive reporting must be kept distinct from causal interpretation. Event counts describe observations, while comparisons and attribution require additional information. The combination of a defined primary measure, limited paired observations, no comparator, and absent numerical endpoint results makes careful reporting of uncertainty and missingness especially important.

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 principal trial-specific limitation is the small evaluable group for the primary endpoint. The registry reports enrollment of 7 and paired baseline and post-treatment tumor measurements for 4 participants. It attributes the limited evaluable group to early termination, but does not state the participant-level reasons for unavailable measurements. It also does not describe how missing values were handled or whether any sensitivity analyses were performed.

The study had a single-group, unmasked design and no comparator arm. As a result, any within-participant change would be descriptive and could not be interpreted as a randomized treatment effect. The registry does not report whether tumor measurements were assessed by independent reviewers or whether measurement assessors were masked; those details should not be assumed.

The status is terminated, but the reason for termination is not reported in the registry record. The primary completion date is listed as 2024-12-16. The record does not provide the numerical primary outcome result, the standard deviation, confidence intervals, or a p-value. Thus, the clinical endpoint’s magnitude and precision cannot be evaluated from the posted results.

The registry lists 12 outcomes and no analysis records, while the statistical analysis plan, multiplicity approach, and analysis population definitions are not reported. The sample-size justification is not reported either. The available safety information gives counts and selected event terms but does not provide a control group or establish causality. These limitations restrict interpretation to the study’s stated objectives and descriptive registry information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Immune Modulation by Abemaciclib in Head and Neck Squamous Cell Carcinoma (HNSCC). (AIM Trial) — NCT04169074.
• Registry record last updated 2026-05-22; status last verified 2026-05.
• Results first posted 2026-05-22.
• 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

NCT04169074 is a Phase II, single-group, unmasked window trial of neoadjuvant abemaciclib for HPV-negative HNSCC, sponsored by the University of Arizona. The registry lists enrollment of 7, study start on 2021-07-07, primary completion on 2024-12-16, and status as terminated.

The primary endpoint was percent change in index-lesion tumor size using RECIST v1.1 metrics after 10-21 days of treatment, with an additional 7 days allowed for surgical delay. The record says 4 participants completed both required measurements, but the numerical mean change and standard deviation are not reported in the registry record. Safety information lists 2 participants with serious adverse events, 6 with other adverse events, and zero deaths. The reason for termination and detailed statistical analysis methods are not reported.