A Study of Axitinib in Advanced Carcinoid Tumors: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Axitinib in Advanced Carcinoid Tumors (NCT01435122), a na phase 2 study. The primary outcome is Rate of Progression Free Survival (PFS).

2. Clinical Question

The study asks whether axitinib can be associated with a period in which advanced carcinoid tumors remain free of defined progression or death. The primary outcome is a percentage of participants meeting the progression-free survival definition at 12 months. Progression-free survival is measured from the initial axitinib dose until objective tumor progression under RECIST criteria or death.

The registry also lists tumor response rate, 24-month overall survival rate, time to treatment failure, and occurrence of possibly related adverse events as secondary outcomes. These outcomes address different aspects of disease status, survival, treatment duration, and safety; they are not substitutes for the primary endpoint. The record does not report the results for these outcomes.

This is a single-group study, not a randomized comparison. It can describe outcomes observed among participants treated in the study, but the registry record does not establish how those outcomes compare with outcomes under another treatment or with no study treatment. The stated primary question is therefore about the observed 12-month progression-free survival rate in this group, not a comparative treatment effect.

3. Trial Design

The registry describes a Phase II, single-group study of axitinib in advanced carcinoid tumors. It lists enrollment of 30 participants and the study status as completed. The listed study start is 2011-10-25, and the primary completion date is 2017-01-11. The sponsor is H. Lee Moffitt Cancer Center and Research Institute.

There is no allocation to different arms and no masking. The registry lists an Axitinib Administration group and describes axitinib as an investigational drug available as tablets, taken orally with food. The record does not provide a like-for-like control group. Consequently, the design does not support a randomized comparison between axitinib and another intervention.

The primary endpoint is the rate of progression-free survival at 12 months, expressed as a percentage of participants. The stated population is all participants. Progression-free survival runs from administration of the initial dose until objective tumor progression according to RECIST or death. Secondary outcomes include tumor response rate, 24-month overall survival rate, time to treatment failure, and possibly related adverse events.

The registry record does not report the protocol’s statistical analysis plan, the method used to estimate the primary endpoint, or a sample-size justification. The sample-size assumptions associated with planning illustrations are not evidence of the study’s design rationale or an analysis performed in the trial. The record also does not report a primary endpoint result, so the study’s observed progression-free survival rate cannot be interpreted from this entry.

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.

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 participants.

6. Primary Endpoint

The registry lists the primary outcome as Rate of Progression Free Survival (PFS), measured over 12 Months.

The primary endpoint is the rate of progression-free survival at 12 months, reported as a percentage of participants. Progression-free survival is defined from the initial axitinib dose until objective tumor progression under RECIST criteria or death. Combining progression and death into an endpoint captures either of these events as a failure to remain progression-free during follow-up.

The registry describes progressive disease as the appearance of new lesions or unequivocal progression of existing non-target lesions. It cautions that progression of non-target lesions should represent an overall change in disease status, rather than an increase in a single lesion, and should not normally override target-lesion status. Stable disease is described as neither enough shrinkage for partial response nor enough increase for progressive disease, using the smallest sum of diameters while on study as the reference.

In general, a fixed-time progression-free survival rate communicates the proportion of a study group estimated to be alive without progression at a specified time. It can be clinically and statistically informative because it focuses on disease control over a defined follow-up period. However, its interpretation depends on how events, follow-up, and participants without a recorded event are handled. Those analytic details and the actual 12-month rate are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods determine how trial observations are converted into estimates and how uncertainty around those estimates is described. The registry record gives the primary endpoint definition and the intended population, but it does not report the analysis method used to calculate the 12-month progression-free survival rate. The statistical concepts below are general explanations, not claims about procedures used in this study.

What does a progression-free survival endpoint represent?

Progression-free survival is a time-to-event outcome. Each participant’s time begins at the initial axitinib dose, and the event is the first qualifying tumor progression or death. A participant who has not had either event by a given point in follow-up may contribute information about remaining progression-free up to that point. The registry defines progression using RECIST and describes how progressive disease and stable disease are distinguished.

In general, time-to-event methods are useful when participants have different lengths of follow-up or when some participants have not experienced the event by the end of observation. Such methods can use the information available up to the last known follow-up for participants who leave observation without a recorded event. This is often described as censoring. The validity of an estimate can depend on why follow-up ended and on whether the method’s assumptions are reasonable. The registry record does not say how censoring was handled, whether any participants were censored, or which estimator was used.

What does a rate at a fixed time mean?

A 12-month progression-free survival rate is an estimate of the share of the study population still alive without progression at that time point. It is distinct from the number of participants who had an event at any time during the study: the timing of events and the amount of follow-up matter. A confidence interval, when reported, describes statistical uncertainty around an estimate under the method used. A narrower interval generally indicates greater precision, while a wider interval indicates greater uncertainty. No 12-month estimate or confidence interval is reported in this registry record.

The endpoint is expressed as a percentage of participants, but the record does not report whether the percentage was calculated directly from observed counts or estimated using a time-to-event method. Those approaches can differ, particularly when follow-up varies or observations are incomplete. The method, assumptions, and any sensitivity analyses are not reported in the registry record.

Why does the design affect interpretation?

This is a single-group study with no allocation to a comparator and no masking. In general, a single-group estimate describes outcomes in the enrolled group; it does not by itself estimate a difference between treatments. Random assignment in a comparative design can help balance known and unknown prognostic factors across groups. That protection is not available for a single-group comparison with an external expectation or historical result. The registry record does not identify a control group or specify a benchmark for the primary endpoint.

Masking can reduce the influence of knowledge of treatment assignment on some assessments or decisions. The record lists masking as none. It does not explain whether endpoint assessments were independently reviewed or what safeguards, if any, were used to apply RECIST consistently. These assessment details are not reported in the registry record.

How should planning illustrations be understood?

Sample-size calculations are planning tools. The assumptions recorded for the planning illustration include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated share of the observed effect. These assumptions describe an illustration, not the actual single-group study design: the trial record lists no allocation and no comparator arm. Planning values are not observed outcomes and are not observed power. The registry record does not report the trial’s own sample-size justification or state that these illustration assumptions were used to design the study.

In general, a planning calculation depends on the endpoint, the target effect, variability or event assumptions, the significance level, and the desired power. Changing assumptions changes the required sample size. A calculation based on an effect observed in the same study is especially not a replacement for estimating that effect with uncertainty. No numerical planning results or primary endpoint estimate are reported in this registry record.

What can be assessed from the posted statistical information?

The record specifies the endpoint, its time origin and event definition, and an intended analysis population of all participants. It does not report a statistical analysis plan, a test, a confidence interval method, a missing-data approach, or the actual primary analysis. The registry lists 0 analyses. As a result, readers cannot evaluate whether the analysis followed prespecified methods or compare a reported estimate with a stated analysis plan.

These omissions do not show that a particular method was or was not used outside the registry entry. They mean only that the method cannot be assessed from the registry record. General explanations of survival analysis or uncertainty should not be mistaken for a description of the study’s actual analysis.

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("Axitinib Administration")
n      <- c(30)
events <- c(22)
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  Axitinib Administration  30  22  73.3  54.1  87.7  55.6  85.8  55.4  85.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and several secondary outcomes: tumor response rate, 24-month overall survival rate, time to treatment failure, and occurrence of possibly related adverse events. When a study evaluates multiple outcomes or performs multiple statistical tests, the chance of obtaining at least one apparently notable result can increase. Statistical plans may address this through a prespecified hierarchy, adjustment, or another approach. These are general considerations; the registry record does not report a multiplicity strategy, a testing hierarchy, or adjusted results.

The record identifies the primary endpoint population as all participants. That statement specifies the intended population for the endpoint, but it does not describe the analysis population actually used or how participants with missing measurements or incomplete follow-up were handled. The registry record does not report the number of participants contributing to the primary analysis, reasons for missing data, imputation methods, censoring rules, or sensitivity analyses. Therefore, the impact of missing information on the endpoint cannot be assessed from this entry.

The record also does not report a statistical analysis plan or any analyses; it lists 0 analyses. This absence of registry-reported detail should not be interpreted as evidence that no analysis or planning existed outside the registry. It limits what can be verified from the posted information. In particular, readers cannot determine from this record whether outcome definitions, analysis populations, handling of incomplete observations, or multiplicity decisions were prespecified.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: abdominal pain (10.0%), fatigue (10.0%), colitis (6.7%), nausea (6.7%), pancreatitis (6.7%).

The registry records adverse events for the Axitinib Administration group. In the serious-event figures, 30 participants are listed as at risk and 12 as affected. In the other adverse-event figures, 30 are listed as at risk and 30 as affected. The registry also lists serious-event terms with percentages: abdominal pain and fatigue at 10.0% each; colitis, nausea, pancreatitis, and vomiting at 6.7% each.

These are descriptive safety figures from the study group, not comparisons between randomized groups. The record does not provide a comparator arm, so the figures cannot establish how event occurrence differed from another treatment or from no study treatment. The percentages for the listed terms should not be added together: the record does not say whether participants could have more than one event, and the terms may describe overlapping experience.

The registry does not report the event definitions, observation periods, severity grades, or details of attribution for these figures. It lists possibly related adverse events as a secondary outcome, but the displayed serious-event terms alone do not establish causality. Deaths are not reported in the adverse-event figures.

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

The record establishes that this completed Phase II study was designed to describe axitinib in advanced carcinoid tumors, with 12-month progression-free survival as its primary endpoint. It defines the event in terms of objective progression under RECIST or death and names all participants as the primary population. Those details help clarify the intended question.

The record does not report the numerical primary endpoint result. It therefore cannot show the observed 12-month progression-free survival rate or how precisely that rate was estimated. Without an estimate and its uncertainty, readers cannot judge whether the result was compatible with a wide range of possible outcomes or was estimated with greater precision. The listed secondary outcomes likewise have no results reported in this registry record.

Even if an outcome estimate were available, a single-group design would describe the experience of participants in the study rather than establish a comparative treatment effect. There is no randomized control group in the record. Differences from outcomes in another setting could reflect factors other than treatment, and the entry does not provide a benchmark for interpreting the endpoint.

The safety entries give descriptive counts and percentages for adverse events, but do not establish that axitinib caused those events or how its safety compares with another option. The registry record also omits details needed to assess the primary analysis, including the estimator, missing-data handling, and uncertainty estimates. Accordingly, the available information supports a description of the design and some recorded safety observations, not a conclusion about efficacy or comparative benefit.

14. Why This Trial Matters Statistically

This trial is statistically notable as a single-group Phase II study with a time-to-event primary endpoint expressed at a fixed time point. Its progression-free survival definition combines objective tumor progression and death, and the registry specifies the initial dose as the time origin. Clear endpoint definitions matter because they determine which observations count as events and how the outcome is interpreted.

The design also illustrates an important distinction between describing an outcome and estimating a treatment effect. A single-group result can summarize the experience of the enrolled participants, but without a concurrent comparator it cannot isolate the treatment’s effect from other explanations. The record lists no allocation and no masking, so it does not present a randomized, masked comparison.

For statistical interpretation, endpoint definitions alone are not enough. Readers also need the estimation method, uncertainty, follow-up and censoring details, and the treatment of missing information. The registry record does not report these analytic details or the primary endpoint result. Its safety figures can be read descriptively, but they do not supply a comparative safety estimate.

The record further distinguishes the intended clinical outcomes from planning illustrations. Sample-size calculations based on an observed effect are not observed power and do not replace an outcome estimate. Here, the illustration assumptions describe a hypothetical two-arm planning framework, while the trial itself is single-group. Keeping those purposes separate is essential when assessing what the statistical record can support.

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 interpreting this study from the registry record is that no primary endpoint result is reported. The endpoint is defined, but no 12-month progression-free survival estimate or uncertainty interval is available. Results for the listed secondary outcomes are also not reported.

The design is single-group, with no allocation and no comparator. This limits causal and comparative interpretation even if descriptive outcome results were available. Masking is listed as none. The record does not describe independent endpoint review, assessment procedures, or measures used to standardize progression determinations.

Important analytic details are absent from the registry record. These include the statistical method for estimating the fixed-time progression-free survival rate, handling of censoring and missing data, the analysis population actually used, and any sensitivity analyses. The entry does not report the trial’s statistical analysis plan or sample-size justification. It lists 0 analyses.

The safety information is also limited: the record does not give event definitions, severity grades, observation periods, or detailed attribution. The recorded counts and term percentages are not comparative evidence. These limitations describe what can be assessed from the registry record; they do not establish whether further analyses or documentation exist elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Axitinib in Advanced Carcinoid Tumors — NCT01435122.
• Registry record last updated 2018-10-02; status last verified 2018-08.
• Results first posted 2017-05-25.
• 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 describes a completed Phase II, open-label, single-group study of axitinib in advanced carcinoid tumors, with enrollment of 30 participants. The primary endpoint is the percentage of participants with progression-free survival at 12 months, defined from the initial dose until objective progression under RECIST or death. The stated primary population is all participants.

No numerical primary or secondary outcome results are reported in the registry record. The adverse-event entries list 12 affected among 30 at risk for serious events and 30 affected among 30 at risk for other events, along with percentages for several serious-event terms. The record does not include a randomized comparator, a reported statistical analysis plan, or details of missing-data handling.