SB-715992 in Treating Patients With Recurrent or Metastatic Head and Neck Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for SB-715992 in Treating Patients With Recurrent or Metastatic Head and Neck Cancer (NCT00095628), a na phase 2 study. The primary outcome is Antitumor Activity of SB-715992 Using Objective Response Rates (Partial and Complete Responses).

2. Clinical Question

This is a question about tumor response in a selected group of patients, not a direct test of whether ispinesib performs better than another treatment. A single-group study can describe the frequency of an outcome under the study’s treatment and assessment conditions. Without a concurrent comparator, it cannot separate treatment-associated outcomes from other influences, such as the course of the disease or differences in patient characteristics. The registry record does not report further details that would clarify how the listed cancer types were represented among the analyzed participants.

3. Trial Design

This was a phase 2, single-group study sponsored by the National Cancer Institute (NCI). The registry record gives enrollment as 21 and states that 20 eligible patients were analyzed for the primary outcome. The reason that the analysis population differs from enrollment is not reported in the registry record. The study is marked completed; its recorded start is 2005-01 and its primary completion is 2010-07.

Participants received ispinesib, identified in the record as SB-715992. The treatment description specifies an intravenous infusion over 1 hour on day 1, with courses repeating every 21 days in the absence of disease progression or unacceptable toxicity. The record also lists laboratory biomarker analysis and a pharmacological study as interventions, but does not report their results.

Allocation is listed as not applicable, and masking is listed as none. Together with the single-group model, this indicates that the registry record does not describe randomized assignment or a blinded comparison. There is no like-for-like control group against which to interpret the treated group’s outcomes. The study can therefore provide a descriptive account of outcomes among its analyzed participants, but cannot by itself estimate a treatment contrast against a concurrent alternative.

The primary outcome was objective response, defined using RECIST v1.0, with assessment by MRI. The stated timeframe was up to 18 months. Secondary outcomes listed in the record include duration of objective response, clinical and objective stable disease, median overall survival, and median time to progression. The registry record does not report results for these listed outcomes or a detailed statistical analysis plan. It also does not report a sample-size justification, planned interim analyses, or further details about assessment scheduling.

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: 20 eligible patients were analyzed

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: A total of 21 patients were enrolled onto the study. One patient was ineligible due to disease progression prior to treatment. So a total of 20 evaluable patients were analyzed

6. Primary Endpoint

The registry lists the primary outcome as Antitumor Activity of SB-715992 Using Objective Response Rates (Partial and Complete Responses), measured over Up to 18 months.

The primary endpoint is the number of participants with an objective response, meaning a complete response or a partial response. Under the registry’s description of RECIST v1.0, a complete response is the disappearance of all target lesions. A partial response requires a decrease of at least 30% in the sum of the longest diameters of target lesions. The registry record says assessment was by MRI and gives a timeframe of up to 18 months.

Objective response is used as a way to describe measurable tumor change during a study. Combining complete and partial responses into an objective-response outcome gives a count of participants meeting either of the stated response definitions. The count, together with the population assessed, would describe how often such a response was observed under the trial’s assessment conditions. It does not by itself describe how long a response lasted, whether disease remained stable without meeting response criteria, or how survival compared with another treatment. Those topics are distinct outcomes, and the record lists several of them as secondary outcomes.

The registry record says that 20 eligible patients were analyzed, but does not report the number with complete or partial response. It therefore does not provide the observed primary endpoint result or enough information to calculate a response proportion or its uncertainty. Those missing results also prevent a numerical interpretation of the endpoint’s precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count endpoint represent?

The primary endpoint is expressed as a number of participants with an event—in this case, an objective response. A count is a direct summary of how many people met the endpoint definition. To interpret it as a frequency, the count must be read alongside the number of people assessed. Here, the registry record identifies 20 eligible patients as analyzed but does not report the number who responded. Without both pieces, the observed response frequency cannot be described.

In general, a binary outcome classifies each participant into one of two categories for a specified endpoint, such as response or no response. The endpoint definition determines which category applies. For this study, the record defines response as complete or partial response under RECIST v1.0. It does not state in the posted results how many participants fell into either category, how participants without an assessable scan were classified, or how missing assessments were handled.

Why does the study design matter?

In a single-group study, outcomes are observed among participants receiving the study treatment, without a concurrent comparison group. This can describe what happened in that group, but it does not directly estimate a difference between treatments. General statistical interpretation of a treatment effect usually depends on a comparison that accounts for what might have happened to similar participants under another treatment or control condition. Such a comparison is not reported.

Random allocation, when used, is intended to make treatment groups comparable on average with respect to measured and unmeasured characteristics. This study’s allocation is recorded as not applicable and its model as single group, so that design feature is absent. The lack of masking is also recorded. The registry record does not describe procedures that would reduce the influence of knowledge of treatment assignment on assessments. This is relevant context for an endpoint based on tumor imaging, although the record does not establish that assessment was biased.

What would uncertainty estimates add?

In general, a confidence interval expresses uncertainty around an estimate. For a response frequency, it would help distinguish the observed result from the range of values that remain compatible with the data under the interval’s assumptions. With limited data, an observed frequency can be imprecise; the interval communicates that uncertainty more directly than a point estimate alone. No response count, response estimate, or confidence interval is reported in the registry record, so none can be interpreted for this endpoint.

For binary outcomes, statistical methods often use a binomial model, which treats each participant’s endpoint status as an event or non-event. The usefulness of a model depends on details such as how the analysis population was formed, whether observations are independent, and how missing outcomes were handled. Those details are not reported in the registry record. The record’s description of 20 eligible patients analyzed supplies a population size, but not the endpoint data or the analysis assumptions needed to reproduce an estimate.

What do the planning illustrations mean?

In general, sample-size calculations ask how many participants might be needed to detect a specified effect under stated assumptions. They are planning exercises, not findings from participants. The planning description associated with this trial states that its illustrations use the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it also says the target effect is a stated fraction of the observed effect. For time-to-event illustrations, the quantity is a total number of events, while other illustrations are expressed as participants per arm.

These assumptions describe a planning framework, not the trial’s own design. The actual study is single group, and the record does not report a two-arm comparison, its own sample-size justification, or the observed primary effect required to interpret such illustrations. Any planning estimate based on an observed effect should not be read as observed power or as evidence that the study had adequate power. No numerical planning result or observed response effect is reported in the registry record.

How should time-to-event outcomes be distinguished?

The record lists duration of objective response, median overall survival, and median time to progression as secondary outcomes. These are time-to-event concepts, which differ from a simple count of participants meeting a response definition. In general, time-to-event analyses account for both the time until an event and participants whose event time is not observed during follow-up. Their interpretation depends on the event definition, follow-up, censoring rules, and analysis method. Those details and the outcome results are not reported in the registry record. It is therefore not possible to describe the time-to-event findings or evaluate their statistical treatment.

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("Treatment (Ispinesib)")
n      <- c(20)
events <- c(0)
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  Treatment (Ispinesib)  20  0  0.0  0.0  16.8  0.0  16.1  0.1  16.1

11. Multiplicity, Missing Data and Analysis Populations

The registry record identifies objective response as the primary outcome and lists several secondary outcomes: duration of objective response, clinical and objective stable disease, median overall survival, and median time to progression. Considering multiple outcomes can raise a multiplicity question: when many statistical tests are conducted, the chance of at least one apparently noteworthy result can increase. General approaches include prespecifying a primary outcome, adjusting significance thresholds, or treating secondary analyses as exploratory. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or statistical test results. It is therefore not possible to determine whether or how multiplicity was addressed.

Missing-data handling is also not reported in the registry record. Enrollment was 21, while 20 eligible patients were analyzed for the primary outcome. The reason for this difference is not stated, and the record does not describe whether the excluded participant was ineligible, lacked an assessment, or was omitted for another reason. It also does not state how missing imaging or unevaluable response status would be treated. These details matter because the denominator and classification of participants can affect a binary endpoint summary.

The record does not provide a detailed analysis-population definition beyond the statement that 20 eligible patients were analyzed. It does not report whether the analysis included all enrolled participants, a subset meeting eligibility criteria, or another prespecified population. No sensitivity analysis for missing data or alternative population is described. Consequently, readers cannot assess the robustness of a primary endpoint result—and the primary result itself is not reported in the registry record.

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: dyspnea (10.0%), febrile neutropenia (10.0%), anorexia (5.0%), cough (5.0%), leukopenia (5.0%).

The registry record reports serious adverse events for the ispinesib treatment group. It lists 20 participants at risk and 6 participants affected by serious adverse events. The record also names dyspnea and febrile neutropenia at 10.0% each, and anorexia, cough, leukopenia, and neutropenia at 5.0% each, among the top serious event terms. The record does not state whether participants could contribute to more than one event term, so those percentages should not be added together.

These figures are safety summaries, not estimates of treatment benefit. In general, a participant count describes how many people in the recorded group were affected, while a percentage expresses a reported frequency for an event term. Interpretation depends on how events were defined, collected, coded, and attributed; further details are not reported in the registry record. The record gives a group at-risk count, but does not provide event timing or duration in the information available for this summary.

Deaths are not reported in the registry record. The serious adverse event figures should therefore be read as the reported safety counts and terms, not as a complete account of all possible safety outcomes.

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

The registry record establishes that a phase 2, single-group study evaluated ispinesib in patients with recurrent or metastatic head and neck cancer. It describes the primary endpoint as the number of participants with complete or partial response under RECIST v1.0, assessed by MRI for up to 18 months. It also states that 20 eligible patients were analyzed. These details clarify what the study set out to measure and the population size attached to the endpoint.

However, the record does not report the number of complete or partial responses. Without that result, it is not possible to say how many participants met the primary endpoint, estimate the observed response frequency, or assess its precision. The listed secondary outcomes likewise have no results reported in the registry record. The study’s treatment schedule and endpoint definitions cannot be used to fill in those missing findings.

Even if the response result were available, the design would still shape its meaning. A single-group study can describe outcomes among participants receiving the treatment under the study conditions. It cannot, without a concurrent comparator, establish how those outcomes compare with another treatment or separate the treatment’s contribution from other influences. No claim about comparative efficacy follows from the design information alone.

The registry record also does not explain the difference between enrollment of 21 and analysis of 20 eligible patients. This leaves uncertainty about the formation of the analysis population and the handling of participants without an evaluable outcome. The safety summary provides separate counts and event terms but does not replace the missing efficacy results. In short, the record supports a description of the study design, endpoint, treatment schedule, and some safety reporting; it does not support a numerical conclusion about the primary response outcome or a comparative treatment effect.

14. Why This Trial Matters Statistically

This trial illustrates why a clearly defined endpoint and a reported endpoint result are both necessary for statistical interpretation. The record specifies what counts as an objective response under RECIST v1.0 and identifies the analysis population, but does not give the response count. A definition makes an outcome interpretable; it does not reveal what was observed. Without the result, the central efficacy question remains quantitatively unanswered in the registry record.

The design also illustrates the distinction between describing outcomes and estimating comparative effects. A single-group study can document outcomes among treated participants. It does not provide the concurrent control needed to estimate a treatment contrast within the trial. This distinction remains important even when a study has a named primary outcome and a specified assessment timeframe.

Finally, the record highlights the value of transparent reporting around analysis populations, missing outcomes, multiplicity, and precision. Enrollment is reported as 21, while the primary analysis is described as involving 20 eligible patients; the reason for the difference is not stated. No response estimate or uncertainty interval is reported, and the statistical analysis plan is not detailed. These omissions limit reproducibility and the reader’s ability to judge how stable an outcome estimate would be. The study is therefore statistically informative about its design and measurement framework, while its registry record leaves key outcome and analysis details unavailable.

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 limitation for interpreting the primary endpoint is that the response result is not reported in the registry record. Although the endpoint definition, timeframe, and analysis population are stated, the number of participants with complete or partial response is missing. No estimate of the response frequency or uncertainty can be described from the record.

The study’s single-group design also limits interpretation. There is no concurrent comparator, and allocation is listed as not applicable. As a result, the design does not support a within-trial estimate of how outcomes differ from those under another treatment. Masking is listed as none; the record does not describe additional safeguards for outcome assessment.

Enrollment is reported as 21, but 20 eligible patients were analyzed for the primary outcome. The reason for the difference, the full analysis-population definition, and the handling of missing or unevaluable assessments are not reported in the registry record. These gaps make it difficult to assess the potential effect of exclusions or missing data.

The registry record lists secondary outcomes but does not report their results. It also does not provide a detailed statistical plan, a multiplicity approach, a sample-size justification, or information about interim analyses. The safety summary reports serious adverse event counts and selected event terms, but deaths are not reported. These limitations restrict interpretation to the design and the specific outcomes and safety figures that the record actually describes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: SB-715992 in Treating Patients With Recurrent or Metastatic Head and Neck Cancer — NCT00095628.
• Registry record last updated 2017-03-06; status last verified 2017-01.
• Results first posted 2017-03-06.
• 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

This completed phase 2 study evaluated ispinesib (SB-715992) in recurrent or metastatic head and neck cancer using a single-group design. Enrollment was 21; the primary outcome description states that 20 eligible patients were analyzed. Treatment was given intravenously over 1 hour on day 1, with courses repeating every 21 days in the absence of progression or unacceptable toxicity.

The primary endpoint was the number of participants with complete or partial response under RECIST v1.0, assessed by MRI for up to 18 months. The number of responders is not reported in the registry record, and no results for the listed secondary outcomes are reported. Serious adverse event figures include 6 affected participants among 20 at risk. The single-group design and missing primary result prevent a numerical interpretation of comparative treatment effects or the observed response frequency.