Neoadjuvant Imatinib in Dermatofibrosarcoma Protuberans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Neoadjuvant Imatinib in Dermatofibrosarcoma Protuberans (NCT00243191), a non-randomized phase 2 study. The primary outcome is To Collect Matched Tumor Tissue of Trial Participants With Dermatofibrosarcoma Protuberans Before and After Treatment With Imatinib for Future Use in cDNA Microarray and Tissue Array Studies..

2. Clinical Question

The broad study purpose was to examine the effect of imatinib on DFSP tumors. The registered primary outcome is more specifically framed around obtaining tissue for molecular studies, not around a clinical tumor response measure. Therefore, the record supports describing the intended biological question and study structure, but not estimating an observed treatment effect on tumors or on PDGFRB signaling.

3. Trial Design

This was a phase 2, single-group, non-randomized study with no masking. The registry lists imatinib mesylate as the intervention and an enrollment of 18. The study status is completed. Its recorded start was 2006-05, and its primary completion was 2009-09. Those dates describe the registry timeline; they do not establish when each participant received treatment or when individual tissue samples were obtained.

The primary outcome focused on collecting matched tumor tissue before and after imatinib treatment. Its timeframe is stated as prior to and after 2-weeks of therapy, while the outcome description refers to assessing tissue after up to 2 weeks of treatment. The goal was to compare the level of phosphorylated platelet-derived growth factor receptor beta (PDGFRB) in DFSP before and after treatment. The record also says tissue would be evaluable if adequate pre-treatment and on-treatment tumor tissue were available for the proposed molecular studies. The remainder of the population description is incomplete in the registry record.

Because the study had a single group, there was no randomized treatment contrast and no like-for-like control arm. A within-participant comparison of paired samples can address a different question from a comparison between treatment groups: it focuses on changes in tissue measurements over time among participants with usable samples. The registry record does not report how many pairs were evaluable, the measured PDGFRB values, or a statistical analysis of change. It also lists no analyses. These omissions prevent interpretation of an observed primary outcome estimate.

The sponsor was Sarcoma Alliance for Research through Collaboration. The study title identifies neoadjuvant imatinib in DFSP. The registry’s stated purpose concerns biological effects in tumor tissue; the record does not provide a clinical efficacy conclusion or a treatment-versus-control comparison.

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

Analysis population for the primary outcome, as defined in the registry: Population of paired tissue samples collected from patients with confirmed diagnosis of dermatofibrosarcoma protuberans. Tissue sample will be considered evaluable if there is adequate pre-treatment and on-treatment tumor tissue available for the proposed molecular studies, and resection of DFSP was completed after receiving imatinib.

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 To Collect Matched Tumor Tissue of Trial Participants With Dermatofibrosarcoma Protuberans Before and After Treatment With Imatinib for Future Use in cDNA Microarray and Tissue Array Studies., measured over Prior to and after 2-weeks of imatinib therapy.

The registry’s primary outcome is titled as the collection of matched tumor tissue from trial participants before and after treatment, for future cDNA microarray and tissue array studies. Its unit is paired tumor tissue samples, its parameter is a number, and its timeframe is prior to and after 2-weeks of imatinib therapy. In practical terms, this outcome concerns whether paired specimens were obtained, rather than directly reporting a measured change in tumor size, symptoms, or another clinical outcome.

The accompanying description gives the biological purpose of collecting the specimens: to assess whether imatinib affects autocrine or paracrine stimulated signaling through the platelet-derived growth factor receptor pathway. It specifies a proposed comparison of phosphorylated PDGFRB levels in DFSP before and after treatment. These two aspects should be kept distinct. Tissue collection makes the planned molecular comparison possible, but a count of paired samples does not itself reveal the direction or magnitude of a molecular change.

The registry record does not report the number of paired samples collected or an observed PDGFRB comparison. It also does not report an effect estimate, uncertainty interval, or analysis for this outcome. Accordingly, the endpoint’s purpose and measurement type can be described, but its observed result cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group, non-randomized design without masking. These features determine what kinds of comparisons the study can make. With one group, the registered tissue objective is based on samples obtained from participants before and during treatment. This allows a paired, within-participant comparison in principle, but does not create a randomized control group. In general, random allocation helps make groups comparable on average; without it, a study cannot use randomization to support a causal comparison between separate treatment groups. No such separate groups are listed for this study.

What does a paired comparison estimate?

In general, a paired analysis compares two measurements from the same participant, such as a pre-treatment tissue value and a later tissue value. Pairing can account for stable differences between participants because each participant serves as their own reference. The estimate would describe the change across the paired measurements that were analyzed. It would not automatically establish that treatment caused the change, since other changes over time or features of sample availability may also matter.

For this study, the stated molecular target was phosphorylated PDGFRB in DFSP tissue. However, the primary outcome is registered as the number of paired tissue samples collected, while the description explains the intended molecular comparison. The record does not report either the count of evaluable pairs or numerical molecular measurements. Thus, no paired change estimate can be interpreted from the registry record.

Why does the denominator matter?

In general, an analysis of paired tissue values requires both measurements for each included participant. Participants enrolled in a trial are not necessarily all included in a paired analysis: a specimen may be unavailable or inadequate, or a participant may not have a usable pair. The registry’s outcome description says a sample is evaluable when adequate pre-treatment and on-treatment tumor tissue is available for the proposed molecular studies. It does not give the number meeting that criterion. The listed enrollment of 18 therefore does not establish the denominator for any tissue analysis.

Missing paired measurements can affect both the precision and the representativeness of an estimate. If participants without usable pairs differ from those with usable pairs, the analyzed group may not reflect everyone enrolled. In general, reporting the number assessed, the number with complete pairs, reasons for missing samples, and the analysis population helps readers assess this issue. Those details are not reported in the registry record.

What can a confidence interval tell readers?

In general, a confidence interval expresses the uncertainty around an estimated effect under the assumptions of the analysis. A narrower interval indicates greater statistical precision, while a wider interval indicates less precision. It does not resolve possible bias from missing data, lack of a control group, or an unsuitable measurement model. No estimate or confidence interval for the registered tissue outcome is reported in the registry record, so its precision cannot be assessed.

What is not documented about the analysis?

The record lists no analyses. It does not report a statistical test, model, adjustment strategy, or method for handling multiple outcomes. The protocol’s statistical plan, any interim analyses, and a sample-size justification are not reported in the registry record. Those methods should not be inferred from the phase designation or from the study’s enrollment. In general, a phase label describes the trial’s stage in development; it does not specify the statistical method used for a particular endpoint.

The outcome is a count of paired samples, while the biological objective concerns a comparison of tissue measurements. These are distinct statistical quantities. A count can describe the availability of specimens; a molecular comparison would require the measured values and a defined analysis. The registry record does not supply the numerical results needed for either quantity. It is therefore not possible to evaluate an effect size, its uncertainty, or whether any stated statistical threshold was met.

The study’s single-group structure also means that statistical significance, if reported, would not by itself provide a randomized treatment comparison. General statistical interpretation requires attention both to the estimate and to the design that generated it. Here, the missing outcome analysis and absence of a control arm place strong limits on what can be concluded from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome measure and zero analyses. It does not report a statistical analysis plan, a hierarchy of hypotheses, or a procedure for adjusting for multiple comparisons. The tissue description mentions a biological pathway and a proposed PDGFRB comparison, as well as future cDNA microarray and tissue array studies. The record does not specify how many molecular measurements or exploratory comparisons were planned, or how multiplicity would be handled.

In general, testing multiple outcomes or molecular features can increase the chance of observing an apparently notable result by chance. A prespecified hierarchy or multiplicity adjustment can help address that issue, but neither should be assumed in the absence of registry documentation. The registry record does not report whether either approach was used.

The outcome description defines evaluable tissue as adequate pre-treatment and on-treatment tumor tissue for the molecular studies. It does not report how many participants had evaluable pairs, whether any samples were missing, or how missing measurements were handled. The analysis population is not reported in the registry record. These omissions matter because the number and characteristics of participants contributing paired data affect interpretation of the result.

The record also does not report whether the analysis followed an intention-to-treat, per-protocol, or other population definition. No such approach can be inferred from the enrollment count or from the endpoint’s specimen-based eligibility description. With no posted analysis and no outcome results, neither multiplicity nor missing-data methods can be assessed.

11. 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

Serious events with the highest arm-level rate: chest pain (5.6%), shortness of breath (5.6%), infection (5.6%), pain (5.6%).

For the imatinib group, the registry lists 18 participants at risk for serious adverse events and 2 with serious adverse events. It lists 18 at risk for other adverse events and 0 with other adverse events. These are descriptive counts as recorded; the registry does not provide a comparative safety estimate against another group.

The serious adverse-event terms listed are chest pain, shortness of breath, infection, and pain, each reported as 5.6%. These percentages are attached to the listed terms in the registry record. The record does not provide further event-level details here, so the terms should not be interpreted as a complete account of all clinical circumstances or as evidence of causation.

Deaths are not reported in the registry record. The serious and other adverse-event figures are separate from the primary tissue objective. They do not indicate whether the intended molecular change occurred, and the absence of reported other adverse events should be read as the recorded count rather than as evidence that no unrecorded events occurred.

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

This trial record describes a completed phase 2 study of imatinib mesylate in DFSP, conducted as a single-group, non-randomized study without masking. Its primary outcome concerns collection of matched tissue before and after treatment, with a stated biological aim of comparing phosphorylated PDGFRB levels. These details identify the research question and the kind of evidence the study was designed to generate.

The registry record does not report the number of evaluable paired tissue samples, the measured PDGFRB values, or an analysis of change. It therefore does not show whether the intended molecular comparison found a change, how large any change was, or how precise an estimate might be. No conclusion about the primary outcome can be drawn from the outcome description alone.

The design also does not include a randomized comparator group. In general, a before-and-after comparison in one group can describe measurements over time, but it cannot by itself establish what would have happened over the same period without the intervention. The record contains no comparative clinical outcome analysis, so it cannot support a treatment-versus-control estimate.

The adverse-event entries provide limited descriptive safety information: 2 serious adverse events among 18 at risk, and 0 other adverse events among 18 at risk. The record lists serious-event terms and their reported percentages, but does not report deaths. These data should be interpreted separately from the unreported primary tissue outcome and do not establish a comparative safety profile.

In short, the registry record documents the intended tissue-based research question, the study design, enrollment, timeline, and some adverse-event counts. It does not report the primary result or statistical analysis. The evidence available in the record is consequently insufficient to characterize the observed molecular effect or its uncertainty.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of how the registered endpoint and the scientific objective can differ in emphasis. The primary outcome is recorded as a number of paired tissue samples, while the description explains that those samples were intended to support a comparison of phosphorylated PDGFRB levels. Sample availability and a biological measurement answer different questions. A count of paired specimens would describe the feasibility of obtaining tissue; a comparison of molecular values would describe the observed measurements among analyzed pairs.

The distinction is important for interpretation. Readers need both a clear endpoint and its result to know what was measured and what the data show. Here, the registry record gives the intended timeframe and evaluability concept, but does not report the number of pairs, the molecular values, or an analysis. This prevents assessment of either specimen yield or the proposed biological comparison.

The single-group design also highlights the limits of within-participant evidence. Pairing can reduce the influence of stable differences between participants when comparing repeated measurements, as a general statistical principle. It does not provide a concurrent control or remove all possible changes over time. The design must therefore be considered alongside any estimate, and no such estimate is reported in the registry record.

Finally, the record illustrates why enrollment and outcome-analysis denominators should not be conflated. Enrollment is listed as 18, but the number of participants with adequate matched tissue is not reported. Without that denominator and an account of missing specimens, the representativeness and precision of a molecular estimate cannot be evaluated. The registry’s completed status does not fill these reporting gaps.

14. 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 this trial from the registry record is the absence of a reported primary outcome result. The record does not state how many paired samples were obtained or analyzed, provide the PDGFRB measurements, or report an effect estimate or uncertainty interval. It lists no analyses, leaving the statistical methods and analysis population unspecified.

The study was single-group and non-randomized, with no masking. It therefore had no concurrent control arm for a treatment comparison. A paired pre-treatment and on-treatment approach can be useful for describing within-participant changes, but does not by itself address alternative explanations for changes over time. This is a design limitation, not a finding about the direction or size of any biological change.

The population description is incomplete in the registry record. It mentions confirmed DFSP and the requirement for adequate pre-treatment and on-treatment tissue for evaluability, but does not report the number of participants who met that tissue criterion. The record does not describe missing samples, reasons for missingness, or how incomplete pairs were handled. Enrollment of 18 does not establish the analysis denominator.

The registry does not report the statistical plan, sample-size justification, interim analyses, or multiplicity approach. It also does not provide details sufficient to assess whether the intended molecular studies were confirmatory or exploratory. The adverse-event record offers counts and listed terms, but deaths are not reported and no comparative safety group is available. These limitations restrict interpretation to the study’s recorded design and descriptive information; they do not establish that an unreported analysis was or was not performed outside the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Neoadjuvant Imatinib in Dermatofibrosarcoma Protuberans — NCT00243191.
• Registry record last updated 2012-03-29; status last verified 2012-02.
• Results first posted 2012-03-29.
• 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.

18. Record Summary

NCT00243191 is a completed phase 2 study titled “Neoadjuvant Imatinib in Dermatofibrosarcoma Protuberans.” It was non-randomized, single-group, and unmasked, with enrollment of 18. The recorded start was 2006-05 and primary completion was 2009-09. The intervention was imatinib mesylate, and the sponsor was Sarcoma Alliance for Research through Collaboration.

The primary outcome concerns collecting paired tumor tissue before and after treatment, with a stated objective of comparing phosphorylated PDGFRB levels. The registry record does not report the paired-sample count, molecular results, or an analysis. It lists 2 serious adverse events among 18 at risk and 0 other adverse events among 18 at risk; deaths are not reported in the registry record.