Dasatinib in Polycythemia Vera: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dasatinib in Polycythemia Vera (NCT00538980), a na phase 2 study. The primary outcome is Effect of Dasatinib on the Platelet Count and the Stabilization of Hematocrit When Restored by Phlebotomy to Normal Range.

2. Clinical Question

3. Trial Design

This was a Phase II, non-randomized, single-group study of dasatinib in patients with polycythemia vera. The registry lists an enrollment of 10 and describes the group as “All patients.” Because there was no randomized allocation and no concurrent control group, the design does not support a direct treatment-versus-control comparison. Any changes observed during the study would need to be interpreted as within-group observations, not as an isolated estimate of the causal effect of dasatinib.

The study started on 2007-04-30, and the primary completion date is listed as 2010-08-25. Its status is terminated. The registry states that the primary analysis was not completed because the study was terminated early due to lack of efficacy. The reason for termination is therefore stated, but further detail about the decision process, timing, or supporting evidence is not reported in the registry record.

The planned intervention was oral dasatinib once daily at 100 mg, described as two 50 mg tablets taken together each day, with modifications as indicated. The available arm description is incomplete: it begins to describe conditions involving platelet count or spleen enlargement but does not provide the full modification rules. The full dosing and treatment-duration details are not reported in the registry record.

Laboratory testing for the primary outcome was scheduled weekly for the first month, then every 2 weeks for months 2 and 3, and monthly thereafter. This is a monitoring schedule, not a report of how many measurements were actually collected. The number and timing of completed measurements, participant discontinuations, and treatment exposure are not reported in the registry record.

The registry lists secondary outcomes concerning marrow cellularity, reticulin and fibrous content, cytogenetics, and JAK2 allele burden. It lists five outcome measures, but no completed statistical analyses are recorded. Detailed methods for the secondary outcomes are not reported in the registry record.

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

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 Effect of Dasatinib on the Platelet Count and the Stabilization of Hematocrit When Restored by Phlebotomy to Normal Range, measured over Lab tests will be performed weekly for the first month, then every 2 weeks for months 2 and 3 and monthly thereafter..

The primary endpoint concerns two blood measures: platelet count and hematocrit. The registry describes assessing the effect of dasatinib on platelet count and the stabilization of hematocrit after phlebotomy had restored hematocrit to the normal range, defined as HCT <45% for men and <42% for women. The stated testing schedule was weekly for the first month, every 2 weeks for months 2 and 3, and monthly thereafter.

These measures address the study’s stated clinical and feasibility question: whether the treatment regimen could be used to affect platelet count and maintain hematocrit within the specified range after phlebotomy. Serial laboratory measurements can describe how a marker changes over time, while repeated observations may also help characterize whether a response is sustained. Those are general reasons to measure outcomes repeatedly; they do not establish what happened in this study.

The registry does not provide a unit, a numerical summary, an estimated change, or a statistical comparison for the primary outcome. It explicitly says the analysis was not completed because the study was terminated early due to lack of efficacy. Thus, the endpoint is defined in terms of what was intended to be assessed, but the posted record does not provide an analyzed estimate of platelet-count change or hematocrit stabilization. The actual measurement results and the definition of a successful response are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods discussion must distinguish a planned evaluation from an analysis that was completed. The registry specifies an intended primary outcome and a schedule for laboratory measurements, but it also states that analysis was not completed because the trial ended early due to lack of efficacy. No primary outcome estimate, standard error, confidence interval, or test result is reported in the registry record. Statistical concepts can help explain what those quantities would mean in general, but they cannot supply results that are absent from the record.

What does a single-group design estimate?

In general, a single-group study can describe measurements observed among participants receiving the study intervention. With repeated laboratory testing, investigators might describe values at different visits or changes from an initial assessment. Such descriptions can show the pattern within the treated group, if measurements and analysis results are available. They do not by themselves isolate the effect of treatment, because there is no concurrent group representing what might have happened over the same period without the intervention.

This distinction matters for the present design. The registry identifies a non-randomized, single-group study and does not identify a control group. A before-and-after change, if reported, would be an observed change during treatment, not automatically a causal treatment effect. Factors such as the natural course of the condition, co-interventions, or changes in measurement can influence within-group patterns in general. The record does not state that any such factor influenced this trial.

What would an estimate and confidence interval convey?

In general, an effect estimate is a concise numerical description of the outcome, such as a mean change or a difference between groups. A confidence interval describes the uncertainty associated with an estimate under the analysis assumptions. A narrower interval indicates greater precision, while a wider interval indicates less precision. An interval that includes values compatible with different conclusions can reflect uncertainty rather than proof of no effect.

No primary effect estimate or confidence interval is reported for this study. The statement that the primary analysis was not completed prevents readers from using the registry record to judge either the size or precision of a change in platelet count or hematocrit. The reason for termination is not a substitute for those statistics. It does not tell readers the numerical estimate, the range of plausible values, or the analysis criteria used by the sponsor.

What is the role of a significance test?

In general, a significance test evaluates how compatible data are with a specified null hypothesis under a statistical model. A p-value is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. Its interpretation depends on the analysis plan, model assumptions, outcome definitions, and data actually included.

No primary p-value or completed test is reported in the registry record. It would therefore be inappropriate to infer a test result from the termination statement or from the study’s stated purpose. The analysis plan, including the statistical test and any adjustment or covariate strategy, is not reported in the registry record.

Why can repeated measurements require special care?

In general, measurements from the same participant over time are correlated: one person’s results are not independent observations merely because they were collected at different visits. Analyses of repeated measures should account for that dependence. If observations vary more than a simple model expects, over-dispersion can make standard errors too small if it is ignored; allowing for extra variability can improve uncertainty estimates. These are general methodological points, not claims about the analysis used in this trial.

The registry gives a planned laboratory schedule but does not report the number of visits completed, the repeated-measures model, or how within-participant correlation was handled. The analysis method for the primary outcome is not reported in the registry record. It is therefore not possible to determine whether the planned data were analyzed with a longitudinal model, visit-specific summaries, or another approach.

How should planning calculations be read?

General sample-size planning asks how many participants a future study might need under stated assumptions about the target effect, variability, significance level, allocation, and analysis. Such calculations are planning illustrations, not observations from a completed trial. They are not “observed power,” and they do not establish that a study could detect an effect that was never estimated or tested.

The planning assumptions associated with this record describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They describe an illustrative two-arm calculation, not the design of this single-group trial. Any entries framed as participants per arm for 80% power or another target should be understood as hypothetical planning quantities tied to the stated assumptions, not as actual study enrollment or evidence about efficacy. The registry does not report that those assumptions formed the trial’s original design or sample-size justification.

More generally, sample-size illustrations depend on the effect size chosen. When the effect is scaled as a fraction of an observed effect, the resulting sample size is conditional on that reference effect and the other assumptions. It does not validate the reference estimate. Here, the primary analysis was not completed, and the registry record does not report a primary effect estimate. The calculation assumptions should not be mistaken for a completed outcome analysis or for a documented protocol rationale.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists several outcome domains: the primary endpoint concerns platelet count and hematocrit stabilization, while secondary outcomes concern marrow cellularity, reticulin and fibrous content, cytogenetics, and JAK2 allele burden. Considering multiple outcomes can raise multiplicity concerns in general, because repeated testing may increase the chance of at least one apparently notable result. A prespecified testing hierarchy or adjustment can address some of that concern, but the approach depends on the study plan.

Whether multiplicity was addressed, and how, is not reported in the registry record. The number and definitions of planned comparisons, any outcome hierarchy, and any adjustment procedure are not reported in the registry record. The registry lists zero analyses and does not provide completed results for the secondary outcomes. Therefore, there are no reported secondary-outcome tests to interpret alongside the unfinished primary analysis.

The record does not report the number of participants with available data at each assessment, reasons for missing observations, or an analysis population definition. It is not possible to determine from the registry whether all enrolled patients were included in any outcome summary, whether participants were analyzed according to a specified population, or how incomplete follow-up would have been handled. The planned laboratory schedule does not establish that every scheduled measurement was obtained.

In general, missing-data methods rely on assumptions about why measurements are absent and how missingness relates to observed or unobserved outcomes. Without information about missingness and the analysis approach, the effect of incomplete data cannot be assessed. No missing-data method is reported in the registry record. These gaps limit reproducibility and prevent a detailed appraisal of how outcomes would have been analyzed even apart from the stated early termination.

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 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: dyspnea (10.0%).

The registry lists one patient affected by a serious adverse event among 10 at risk. It also lists dyspnea as a top serious adverse-event term at 10.0%. These are descriptive safety entries. They do not, on their own, establish that dasatinib caused the event, and they do not support comparison with another treatment because the study had no concurrent control group.

The record does not provide a fuller account of event timing, duration, severity, seriousness criteria, relatedness to treatment, management, or outcome. It is therefore not possible to determine from these entries whether the listed term accounts for the serious event or to characterize the event’s clinical course. Those details are not reported in the registry record.

The registry’s other-adverse-event fields list zero at risk and zero affected. Because the record does not explain those fields further, they should not be interpreted as evidence that no other adverse events occurred. Death information is not reported in the registry record. The safety figures should be read as limited registry reporting, not as a complete assessment of the treatment’s safety profile.

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

The registry record establishes that this was a non-randomized, single-group Phase II study of dasatinib in polycythemia vera, with enrollment listed as 10. It identifies platelet count and hematocrit stabilization after phlebotomy as the primary question and describes a laboratory monitoring schedule. It also records that the trial was terminated and that the primary analysis was not completed due to lack of efficacy.

That information does not provide a numerical estimate of the treatment’s effect on either primary measure. The record does not report an average change, participant-level response, confidence interval, or completed statistical test. It therefore cannot establish how much platelet count or hematocrit changed, how consistent any change was, or how precisely an effect was estimated. The stated reason for early termination should be reported as the registry’s explanation, not converted into a quantitative result.

The single-group design does not include a concurrent comparator. Even if within-group measurements had been reported, they would not by themselves distinguish an effect of treatment from other explanations for change over time. The record also does not provide completed analyses of the listed secondary outcomes, so no conclusion about marrow findings, cytogenetics, or JAK2 allele burden can be drawn from the outcome list alone.

The limited safety entries describe reported serious adverse events, not proof of causation or a complete safety profile. They also do not permit comparative safety conclusions. In general, the strength of an inference depends on design, outcome data, precision, and the analysis plan. Here, the incomplete primary analysis and absent statistical results leave the central efficacy question unresolved in the registry record. No treatment recommendation follows from these registry entries.

13. Why This Trial Matters Statistically

This study illustrates why a trial’s stated question and its reported results must be kept distinct. The registry identifies a clinically focused primary endpoint and a schedule for repeated laboratory monitoring, but it also states that the primary analysis was not completed. Without an estimate and uncertainty measure, readers cannot assess the magnitude or precision of the endpoint results. That distinction is important whenever a registry contains a detailed outcome description but no completed analysis.

The design also makes clear why comparator structure matters. A single-group study can be useful for describing feasibility and patterns observed during treatment, but it cannot make the same direct comparison as a randomized, controlled study. This is a general design principle. In this record, no control group is listed, so the treatment effect cannot be separated from time-related or other influences through a concurrent comparison.

Early termination is another reason to distinguish status from evidence. The registry records termination due to lack of efficacy, while the primary analysis remains incomplete. The status and stated reason are important context, but they do not replace the outcome estimate, analysis method, or uncertainty interval. Readers should not infer more quantitative detail than the record reports.

Finally, the record demonstrates the value of transparent reporting about analysis populations, missing measurements, multiplicity, and safety-event details. Those details are not reported in the registry record, limiting assessment of reproducibility and completeness. These reporting limits do not prove that a particular method was or was not used; they identify what cannot be evaluated from the registry entry.

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.

Several trial-specific limitations constrain interpretation. The design is non-randomized and single-group, with no concurrent control listed. As a result, the registry cannot support a direct comparison against another treatment or distinguish treatment-associated change from other changes over time. The enrollment is listed as 10, but the number contributing data to the primary outcome analysis is not reported in the registry record.

The primary analysis was not completed because the trial was terminated early due to lack of efficacy. The registry does not provide primary endpoint estimates, uncertainty intervals, test results, or participant-level outcome data. It is therefore not possible to judge the magnitude or precision of changes in platelet count or hematocrit. The decision process and detailed evidence behind termination are not reported in the registry record.

The registry specifies a measurement schedule but does not state how many scheduled measurements were collected or how missing observations were handled. The analysis population, statistical model, and approach to repeated measurements are not reported in the registry record. The registry also lists secondary outcomes without completed analyses, and does not report how multiplicity was handled.

The treatment description is incomplete. It identifies an oral once-daily dose of 100 mg and notes that modifications could be made, but the available description is truncated before the modification rules are fully stated. Actual treatment exposure and adherence are not reported in the registry record. Baseline characteristics and detailed eligibility criteria are also not reported. Safety reporting is limited to the listed serious-event count and term; event details and death information are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Dasatinib in Polycythemia Vera — NCT00538980.
• Registry record last updated 2017-06-20; status last verified 2017-05.
• Results first posted 2017-06-20.
• 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

The registry describes a Phase II, non-randomized, single-group study of dasatinib in polycythemia vera, sponsored by Weill Medical College of Cornell University. Enrollment is listed as 10. The study began on 2007-04-30, has a primary completion date of 2010-08-25, and is marked terminated.

The planned intervention was oral dasatinib once daily at 100 mg, with modifications as indicated. The primary endpoint concerned platelet count and hematocrit stabilization after phlebotomy restored hematocrit to the stated normal range. The registry says the primary analysis was not completed because the study was terminated early due to lack of efficacy.

The registry also lists secondary outcomes involving marrow cellularity, reticulin and fibrous content, cytogenetics, and JAK2 allele burden, but no completed analyses are recorded. Safety reporting lists one patient affected by a serious adverse event among 10 at risk and dyspnea at 10.0% among the top serious terms. Further outcome and analysis details are not reported in the registry record.