Pacritinib Before Transplant for Myeloproliferative Neoplasms (MPN): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pacritinib Before Transplant for Myeloproliferative Neoplasms (MPN) (NCT02410551), a na phase 2 study. The primary outcome is Progression-free Survival (PFS).

2. Clinical Question

The study’s stated goal was to learn whether pacritinib before standard-of-care drugs and transplant could help control myeloproliferative neoplasms, while also studying safety. Those goals describe the research question, not evidence that the treatment controlled disease or was safe. The primary endpoint could not be assessed in the intended population because the required treatment period was not completed by any enrolled participant. The registry therefore gives no analyzed progression-free survival result for the planned one-year assessment.

3. Trial Design

This was a phase 2, single-group study sponsored by M.D. Anderson Cancer Center. The registry lists enrollment of four and status as terminated. It records a start date of 2015-06-15 and a primary completion date of 2017-01-20. Allocation was not applicable, and masking was none. With no randomized or concurrent comparison group, the study was not designed to estimate a treatment contrast against another assigned group.

The intervention strategy was pacritinib before allogeneic stem cell transplantation. Participants were to begin pacritinib at 200 mg by mouth twice a day and proceed to transplant after at least 60 days but no more than 180 days of pacritinib. Treatment was to stop 21 days before starting the preparative regimen for standard-of-care transplant. The registry also lists busulfan, fludarabine, questionnaires, phone calls and allogeneic stem cell transplantation among the interventions. The brief arm description does not give a complete account of the preparative regimen.

The primary endpoint was progression-free survival, with a protocol assessment planned at one year. The intended evaluable participants were those receiving pacritinib for at least 60 days but less than 180 days and undergoing transplant with a matched related or at least 7/8 matched unrelated donor. The protocol was to enroll at least 21 evaluable participants. The record reports four enrolled participants, all not evaluable because none completed 60 days of pacritinib. It states that no primary analysis was done.

The record does not report a separate control group, a masking procedure, an analysis population beyond the evaluability description, or results for the planned primary endpoint. It also does not report why the study was terminated.

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: Four participants were not evaluable and no analysis was done.

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 Progression-free Survival (PFS), measured over participants who received Pacritinib for >/= 60 days but less than 180 days who undergo transplant with a matched related or at least 7/8 matched unrelated donor. The protocol was to evaluate progression free survival at one year..

Progression-free survival (PFS) is generally a time-to-event endpoint: it describes the time until disease progression or death, according to the definitions and assessment rules set by a study protocol. In general, such an endpoint can describe both whether an event occurred and how long participants remained free of the event. The registry record names PFS as the primary endpoint and says the protocol planned to evaluate it at one year.

The record’s endpoint timeframe narrows the intended population to participants who received pacritinib for at least 60 days but less than 180 days and then underwent transplant with a matched related or at least 7/8 matched unrelated donor. However, the record says that none of the four enrolled participants completed 60 days of pacritinib, so none was evaluable under the stated criterion. No analysis was done.

In general, PFS is used when researchers want to describe disease control over time without relying only on a single assessment at the end of follow-up. Its interpretation depends on how progression and death are defined, how often disease status is assessed, the follow-up period, and how incomplete follow-up is handled. Those operational details are not reported in the registry record. Since there is no analyzed endpoint result, the record does not establish a PFS estimate, a confidence interval, or the timing of progression or death for the planned population.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The main statistical feature is the gap between the endpoint planned by the protocol and the analysis actually recorded. The protocol defined evaluability by treatment duration and transplant circumstances, and it planned to assess PFS at one year. The registry says none of the four enrolled participants completed 60 days of pacritinib and that no analysis was done. Thus, the issue is not a reported estimate with wide uncertainty; no primary endpoint estimate is reported at all.

What does a single-group design allow?

In general, a single-group study can describe outcomes among participants who receive a specified study strategy. It does not create a randomized counterfactual group showing what would have happened to similar participants under a different strategy. Comparisons with historical expectations can sometimes be attempted, but such comparisons depend on assumptions about comparability, measurement, follow-up and changes in care. The registry record does not report a historical comparison or a comparator group for this study.

Allocation is listed as not applicable, consistent with the single-group description, and masking is listed as none. Lack of masking can matter when outcomes require judgment or when participants’ knowledge of treatment affects reporting or care. The extent of any such influence depends on the endpoint and study procedures. The record does not report detailed assessment procedures, so their possible effect cannot be evaluated from the registry information.

How should PFS be understood?

In general, a time-to-event analysis uses the time from a defined starting point until an event, such as progression or death, while accounting for participants who have not had an event by the end of observed follow-up. Those participants are typically treated as censored at their last known event-free time, under stated rules. A survival curve can describe the estimated probability of remaining event-free over time, and a confidence interval conveys uncertainty around an estimate. These are general statistical concepts; the registry does not report a curve, an estimate, a confidence interval, event times, censoring details, or a PFS analysis for this study.

The protocol’s one-year assessment would require clarity about the time origin, definitions of progression and death, follow-up and censoring. The registry’s endpoint wording identifies the planned assessment and the intended evaluable group, but does not report those detailed analysis rules. Without endpoint data and the analysis details, it is not possible to assess the precision of a PFS estimate or the assumptions of a time-to-event model.

Why does evaluability matter?

Eligibility for an analysis population can be defined by events that occur after enrollment, such as completing a treatment period or undergoing a procedure. Here, the registry defines the intended evaluable population using pacritinib duration and transplant criteria. It says all four participants failed to complete the minimum pacritinib period. Therefore, the record reports no participants meeting the described evaluability requirement and no PFS analysis. This prevents an estimate for the specified population; it does not tell the reader what the PFS outcomes would have been if participants had completed the regimen.

In general, excluding participants based on post-enrollment events can affect how representative an analyzed group is, because evaluability may be related to health, tolerability, logistics or other factors. Those possibilities should not be assigned as reasons in this trial: the registry does not report why participants did not complete 60 days. It also does not report whether any other endpoint or exploratory analysis was performed outside the stated primary analysis.

What can planning calculations say?

Sample-size calculations are planning tools. In general, they depend on assumptions about the effect to detect, variability or event rates, significance level, power, allocation and the statistical model. The stated planning assumptions for this record include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a fraction of an observed effect. They describe an illustration, not the trial’s own design or actual allocation. This study is listed as single group, so the equal-allocation assumption in a planning illustration should not be mistaken for the trial design.

Planning sample sizes are not observed power. Observed power is not a substitute for an effect estimate and its uncertainty, and a planning illustration cannot supply a missing endpoint result. The registry record does not report the trial’s sample-size justification or a completed PFS analysis. The posted record also gives no numeric PFS effect to interpret. No additional sample-size calculation or inference can be drawn from the information reported.

What about over-dispersion and model choice?

In general, over-dispersion describes data with more variability than a chosen statistical model expects. It can affect standard errors and the reliability of interval estimates or tests in models for counts and rates. Whether over-dispersion matters depends on the endpoint and model; it is not a universal adjustment. The primary endpoint is time-to-event, and the registry reports no fitted model or endpoint data from which to assess model fit or over-dispersion. The registry does not report a statistical analysis plan, a model specification, or any adjustment procedure.

10. Multiplicity, Missing Data and Analysis Populations

The record lists two outcome measures and reports zero analyses. It names PFS as the primary endpoint, but it does not describe the analysis of that endpoint because no analysis was done. No statistical analysis plan, hierarchy of outcomes, testing sequence, or multiplicity adjustment is reported in the registry record. Therefore, there is no basis for assessing how the study intended to control the chance of false-positive findings across multiple tests.

Missingness and non-evaluability are related but not identical concepts. In general, missing data refers to outcome information that is unavailable for some participants or time points. Non-evaluability is the registry’s stated classification: all four enrolled participants failed to complete the minimum 60-day pacritinib period required for the intended evaluable population. The registry does not say whether PFS data were collected for any participant, how follow-up was handled, or why the treatment period was not completed. Those details are not reported in the registry record.

Because the endpoint was not analyzed, there is no reported imputation, censoring method, sensitivity analysis, or missing-data assumption to evaluate. The record also does not report an intention-to-treat analysis or another analysis population. The only stated population information is the protocol’s evaluability definition and the report that all enrolled participants were not evaluable. This limits both the endpoint interpretation and any assessment of robustness to missing information.

11. 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 1% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists one safety group, titled “Pacritinib Pre- Transplant.” For serious adverse events, four participants were at risk and zero were affected. For other adverse events, four were at risk and one was affected. The recorded number of deaths was zero. These are the posted counts; they should not be read as a comparison with another treatment group, because the study had a single group and no comparator arm.

In general, an “at risk” count identifies participants included in the relevant safety reporting group, while an “affected” count records participants meeting the registry’s reporting category. The record does not provide serious adverse event terms, and it does not state whether the other adverse event was related to pacritinib, transplant, or another cause. A zero count in a category means no affected participants were recorded in that category; it does not establish that the intervention has no risk.

The safety counts do not resolve the primary PFS question. They also do not describe event timing, duration, severity beyond the serious-versus-other categories, or the reason the study was terminated. Such details are not reported in the registry record.

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

The result to take from the record is that the primary analysis was not performed. The protocol planned to evaluate PFS at one year in participants meeting treatment-duration and transplant criteria. The record says none of the four enrolled participants completed 60 days of pacritinib, so all were not evaluable and no analysis was done. There is no reported PFS estimate, confidence interval, or test of a treatment effect.

This does not show that pacritinib before transplant improved PFS, worsened PFS, or had no effect. It also does not establish that the intended regimen was feasible or infeasible for a broader population. The record does not state why participants did not complete the specified treatment period, and the small enrolled group cannot provide a basis for broad conclusions about outcomes.

The design further limits causal interpretation. Because this was a single-group study without a comparator, outcomes could not be contrasted with outcomes under another assigned strategy. In general, observed outcomes in a single group may reflect the study intervention along with participant characteristics, disease course, transplant care and other influences. The record does not permit those influences to be separated.

The safety figures are descriptive: four participants were at risk for serious adverse events and zero were affected; four were at risk for other adverse events and one was affected; deaths were zero. These counts do not prove absence of risk or establish causality. No serious adverse event terms are listed. The absence of a PFS analysis and the limited safety detail mean that the record supports a description of study conduct and recorded counts, rather than an estimate of benefit or a definitive safety conclusion.

13. Why This Trial Matters Statistically

This trial illustrates why a planned endpoint and an analyzed endpoint must be distinguished. The protocol set out a one-year PFS assessment for a specifically defined evaluable population. The registry reports that no enrolled participant met the minimum treatment-duration requirement and that no analysis was done. For statistical interpretation, this is a more fundamental limitation than an imprecise estimate: there is no primary estimate to assess for precision.

The record also demonstrates how post-enrollment criteria shape the population to which a result would apply. The intended population depended on completing pacritinib for a specified period and proceeding to transplant with a qualifying donor. Because no one met the stated evaluability criterion, the planned analysis could not describe outcomes in that target group. The registry does not report why the criteria were not met, so the cause cannot be inferred.

Finally, the single-group design and the lack of an analyzed endpoint constrain the questions the study can answer. Even with outcome data, a single-group study would not provide a concurrent randomized comparison. Here, the record has no PFS analysis at all. The study’s statistical importance is therefore primarily methodological: it shows the difference between enrollment, evaluability, and analysis, and why a planning calculation cannot replace an observed treatment effect with uncertainty quantified around it.

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 record reports enrollment of four, against a protocol target of at least 21 evaluable participants, and states that all four enrolled participants were not evaluable because none completed 60 days of pacritinib. The primary PFS analysis was not done. This leaves no endpoint estimate to interpret and no basis for evaluating its precision.

The single-group design provides no concurrent control comparison. Allocation is listed as not applicable and masking as none. The record does not report a comparator, detailed endpoint assessment procedures, progression definitions, event and censoring information, or a statistical analysis plan. It also does not report why the study was terminated or why participants did not complete the required treatment period.

The safety information is limited to participant counts in serious and other adverse event categories and deaths. No serious-event terms are listed, and the record does not state event causality, timing, or further clinical detail. The record also does not report multiplicity handling, missing-data methods, sensitivity analyses, interim analyses, or a sample-size justification. These limitations mean that the posted information describes the study’s intended question and recorded conduct, but does not support conclusions about PFS or a comparative treatment effect.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pacritinib Before Transplant for Myeloproliferative Neoplasms (MPN) — NCT02410551.
• Registry record last updated 2018-10-30; status last verified 2018-10.
• Results first posted 2018-10-05.
• 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

NCT02410551 is a phase 2, single-group study of pacritinib before allogeneic stem cell transplantation for myeloproliferative neoplasms. The registry lists M.D. Anderson Cancer Center as sponsor, enrollment of four, and terminated status. Allocation was not applicable and masking was none.

The primary endpoint was PFS, with a planned one-year evaluation in participants meeting the specified treatment-duration and transplant criteria. The protocol planned at least 21 evaluable participants. The record says all four enrolled participants were not evaluable because none completed 60 days of pacritinib, and no analysis was done.

Safety counts recorded four at risk and zero affected for serious adverse events, four at risk and one affected for other adverse events, and zero deaths. No serious adverse event terms are listed. A PFS result and detailed statistical analysis methods are not reported in the registry record.