This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Pacritinib for Patients With Lower-Risk Myelodysplastic Syndromes (MDS) (NCT02469415), a na phase 2 study. The primary outcome is Overall Response Rate (ORR).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02469415 |
| Phase | Phase 2 |
| Condition | Leukemia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 3 |
| Arms in the primary outcome | n/a |
| Lead sponsor | M.D. Anderson Cancer Center |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned patients with lower-risk myelodysplastic syndromes (MDS). The registry record lists leukemia as the condition and describes a phase II study. Enrollment was 3. The record does not report further eligibility details or a fuller description of the enrolled population.
Intervention
The intervention was pacritinib, initially administered alone and intended to be combined with 5-azacitidine or decitabine in a later part of treatment. The study’s stated aim was to learn whether these regimens could help control MDS and to study their safety.
Comparator
There was no like-for-like control group. The registry describes a single-group study and lists allocation as not applicable. The intervention was not compared with a separate treatment or control arm in a randomized design.
Primary question
The primary efficacy question was whether participants would meet criteria for an overall response, based mainly on hematologic improvement under IWG-2006 criteria and also including complete remission, partial remission, and marrow complete remission. The registry record says the participants who received medication were not on study long enough for formal response assessment, so it does not give an observed response rate.
3. Trial Design
This was a phase II, single-group study sponsored by M.D. Anderson Cancer Center. The registry lists enrollment of 3, allocation as not applicable, and masking as none. Thus, the record does not describe a randomized comparison or a blinded assessment design. Its title identifies the intended population as patients with lower-risk MDS, while the listed condition is leukemia.
The planned treatment had two parts. In Part 1, pacritinib was given by mouth at 200 mg twice daily, with study cycles administered every 28 days. In Part 2, after 4 cycles, pacritinib was to be combined with 5-azacitidine or decitabine. The record states that pacritinib was decreased to 200 mg in the morning and 100 mg in the evening for the first cycle of combined therapy, but the treatment description ends mid-sentence. Further details of that dose adjustment are not reported in the registry record.
The listed study group is titled Pacritinib + Azacitidine or Decitabine. That group label should not be read as evidence that every participant reached combination treatment: the treatment description separates initial pacritinib treatment from the later combination part. The registry does not report how many participants reached each part or which combination drug, if either, was received by each participant.
The record lists a start date of 2015-09-30, a primary completion date of 2017-06-03, and a status of terminated. It also states that two participants were taken off study after the investigational agent was placed on full clinical hold by the Food and Drug Administration. The record does not report a separate termination date or give further operational details about the study’s closure.
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.
Before assignment: Three participants were registered on this study. One participant withdrew consent before receiving the study medication. Two participants were taken off study when the investigational agent was placed on full clinical hold by the Food and Drug Administration (FDA).
Overall Study
| Stage | Pacritinib + Azacitidine or Decitabine |
|---|---|
| STARTED | 3 |
| COMPLETED | 0 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Pacritinib + Azacitidine or Decitabine |
|---|---|
| Withdrawal by Subject | 1 |
| Investigational agent placed on hold | 2 |
Analysis population for the primary outcome, as defined in the registry: Two participants were taken off study when the investigational agent was placed on full clinical hold by the Food and Drug Administration (FDA). The two participants who received the study medication were not on study long enough to make a formal response assessment.
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.
| Characteristic | Unit | Pacritinib + Azacitidine or Decitabine |
|---|---|---|
| Participants analysed | 3 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 2 |
| Age, Categorical: >=65 years | Participants | 1 |
| Age, Continuous | years | 52 (52 to 69) |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 2 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 3 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Overall Response Rate (ORR), measured over 28 days.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary efficacy outcome was overall response rate (ORR). In general, an overall response endpoint combines participants who meet specified response categories into a response proportion. It is used to describe how often a defined response is observed under stated criteria; it does not, by itself, establish a causal treatment effect, especially when there is no comparison group.
For this study, the registry says ORR was based mainly on hematologic improvement defined by International Working Group IWG-2006 criteria, and also included complete remission (CR), partial remission (PR), and marrow complete remission. Those categories make the endpoint broader than a single remission category. The registry lists the timeframe as 28 days, but does not clarify how that timeframe relates to response assessment or the planned treatment cycles.
The record explains that two participants received study medication but were not on study long enough to make a formal response assessment. It therefore does not report a response count, an ORR estimate, or an uncertainty interval. This absence is not evidence that no responses occurred; it means the posted results do not provide a formal assessment from which an observed response rate can be described.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical limitation is that the primary endpoint has no reported formal response assessment. The registry explicitly says the two participants who received study medication were not on study long enough for such an assessment. Consequently, there is no reported ORR estimate to interpret, no response-category breakdown, and no reported confidence interval or hypothesis test for efficacy. The record does not allow a quantitative conclusion about response frequency.
The small enrollment of 3 also places the study in a very limited descriptive setting. Even if a response estimate had been reported, a result from so few participants would ordinarily be imprecise. In general, a confidence interval describes the uncertainty around an estimated quantity; it does not resolve the absence of a formal outcome assessment. No ORR confidence interval is reported in the registry record.
The single-group design has a separate implication. Without a concurrent control group, outcomes could not be directly contrasted with outcomes under another treatment or under a control condition within this study. General statistical interpretation of a single-group study therefore focuses on what was observed among participants who received the regimen, while recognizing that a treatment effect cannot be isolated from other explanations by a randomized between-group contrast. In this case, even that descriptive efficacy result is unavailable because formal response assessment was not completed.
The registry reports that two participants were taken off study when the investigational agent was placed on full clinical hold by the Food and Drug Administration. This provides a stated reason for those participants’ removal, but it does not supply a response assessment or establish why the study as a whole was terminated. The registry status is terminated; further details about study closure are not reported.
The posted safety figures are descriptive and should be read separately from efficacy. The record lists 3 participants at risk for serious adverse events, 1 affected by a serious adverse event, no participants affected by other adverse events, and no deaths in the listed group. Pneumonia is reported as the top serious term at 33.3%. These figures do not establish that the study drug caused an event; the registry record does not report additional attribution details in the registry record.
In general, an adverse-event percentage in a small group can change substantially with a small change in the number of participants. The listed percentage is therefore a description of this record, not a stable estimate of risk in a broader population. No comparative safety estimate is possible from a single-group study without an appropriate comparison group. The registry does not report inferential safety analyses.
For planning purposes, sample-size illustrations are distinct from observed study results. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. Those assumptions do not describe this single-group study’s design. Such illustrations are not observed power and should not be interpreted as evidence that this trial had a particular probability of detecting an effect.
9. Statistical Methods Explained
There is no inferential analysis of the primary outcome reported in the registry record. The record lists one outcome measure and zero analyses. It does not report an ORR estimate, a test statistic, a p-value, a confidence interval, or an adjusted analysis. In the absence of a formal response assessment, statistical methods cannot recover a response estimate from the information recorded.
What does an overall response rate describe?
In general, ORR is a proportion formed by classifying participants according to prespecified response criteria and then describing the share who meet one or more response categories. The interpretation depends on the precise definition, the assessment schedule, the population included in the denominator, and how unevaluable participants are handled. Here, the registry identifies the response categories and cites IWG-2006 criteria, but it does not provide a formal response assessment for the participants who received medication. It also does not report an analysis denominator or rules for classifying participants without an assessment.
The endpoint combines hematologic improvement with complete remission, partial remission, and marrow complete remission. In general, a composite endpoint can capture several clinically distinct states under one overall measure. That choice can make the headline measure broader, while making the underlying category-specific results important to interpretation. No category-specific counts or results are reported in this record.
Why does the single-group design matter?
In general, random allocation to treatment groups supports a comparison by balancing, on average, both measured and unmeasured factors across groups. A single-group design has no such concurrent comparison. Its observed outcomes, when available, describe the enrolled group but do not provide a randomized estimate of the difference between treatment strategies. The registry lists allocation as not applicable and the model as single group; it also identifies no like-for-like control comparison.
Masking is listed as none. In general, masking can reduce the influence of knowledge of treatment assignment on some aspects of assessment or reporting. The record does not describe blinded response review, and no such procedure should be assumed. It also does not report whether response assessments were centrally reviewed.
What does a confidence interval contribute?
In general, a confidence interval gives a range of values compatible with an estimate under a specified statistical procedure. Its width conveys precision: a wider interval indicates greater uncertainty than a narrower one. An interval does not correct for bias, replace an appropriate comparison, or create information where the endpoint was not assessed. Since no formal ORR estimate is reported, there is no response interval to interpret for this study.
General statistical methods for proportions may use different approaches to account for small samples, but the registry does not report which method, if any, would have been used. No method should be inferred from the endpoint name alone. The record also does not report a prespecified statistical analysis plan, a sample-size justification, an interim analysis plan, or a method for handling participants without formal assessment.
How should the planning illustrations be understood?
The sample-size illustrations are planning illustrations, not observed findings from this trial and not a report of its own enrollment target. Their stated assumptions include a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. The effect to detect is defined as a stated fraction of the observed effect. For time-to-event illustrations, the output is expressed as the total number of events; for other illustrations, it is expressed as participants per arm.
In general, a planning calculation asks how much information might be needed under chosen assumptions. Its answer depends on the assumed effect, variability, design, and analysis. When assumptions are hypothetical, the output is not a guarantee of a future result and is not a measure of the probability that this completed study detected an effect. In particular, the two-arm equal-allocation assumption does not match the registry’s single-group design. The registry record does not report that these assumptions formed the study’s protocol or original design justification.
Why might over-dispersion matter in general?
For count outcomes, a statistical model may assume a particular relationship between the mean and variability. Over-dispersion means that the observed variability exceeds what that model expects. In general, ignoring over-dispersion can make standard errors too small and uncertainty appear lower than it is. This concept is not a reported feature of this trial’s primary endpoint: the endpoint is ORR, and the registry record does not report a count model or an over-dispersion analysis.
Likewise, general methods for time-to-event outcomes address event timing and censoring, but the primary endpoint is ORR, not a time-to-event endpoint. The registry record does not report a time-to-event analysis for the primary outcome. Planning conventions for a time-to-event illustration should not be mistaken for evidence that such an analysis was conducted in this study.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and identifies ORR as the primary efficacy outcome. It does not report a family of statistical tests, a multiplicity adjustment, or a testing hierarchy. Because no analyses are listed, there are no reported p-values whose interpretation would depend on an adjustment for multiple testing. The absence of a reported adjustment does not establish that a particular unreported plan was or was not used; the analysis plan is not reported in the registry record.
Missing outcome information is central to interpretation. The registry states that the two participants who received study medication were not on study long enough to make a formal response assessment. It also says two participants were taken off study when the investigational agent was placed on full clinical hold. Those statements describe the assessment limitation and the reason for removal, but the record does not provide a participant-level accounting of outcome availability or response-evaluable status beyond those details.
The registry does not report a missing-data method, a rule for excluding or classifying participants without assessment, an analysis population definition, or a sensitivity analysis. In general, handling participants without an outcome can affect the estimated response proportion, particularly when the denominator and outcome status are unclear. No method should be assumed for this study, and an ORR denominator cannot be reconstructed from the registry entries.
The record also does not report whether any participants withdrew for other reasons, whether any response data were collected but not posted, or whether additional analysis populations were planned. These omissions limit both reproducibility and assessment of potential bias.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Pacritinib + Azacitidine or Decitabine | 1 | 3 | 33.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Pacritinib + Azacitidine or Decitabine | 0 of 3 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Pacritinib + Azacitidine or Decitabine | 0 of 3 |
Most frequent serious adverse event terms
| Event term | Organ system | Pacritinib + Azacitidine or Decitabine |
|---|---|---|
| Pneumonia | Infections and infestations | 1 of 3 |
Serious events with the highest arm-level rate: pneumonia (33.3%).
The registry lists one group, titled Pacritinib + Azacitidine or Decitabine, with 3 participants at risk for serious adverse events and 1 participant affected. It reports 0 participants affected by other adverse events and 0 deaths. The top serious adverse event term is pneumonia, reported as 33.3%.
These figures are descriptive counts and a reported percentage for the registry’s listed group. They do not establish a causal relationship between treatment and an event. The registry record does not report further detail about event attribution, severity grading, timing, recurrence, or the method used to select the top serious term. The group title should also be interpreted alongside the planned sequence: pacritinib was initially given alone, with combination treatment intended after 4 cycles. The record does not identify which treatment each affected participant received at the time of an event.
Because enrollment was 3, each safety figure reflects a very small study group and should not be treated as a precise estimate for a broader population. The single-group design provides no concurrent comparison for estimating relative safety. The reported absence of deaths in the group is a registry count, not evidence about outcomes beyond the participants and reporting captured in the record.
12. What the Result Does, and Does Not, Mean
The registry record documents a phase II, single-group study of pacritinib for lower-risk MDS, with a planned transition from pacritinib alone to pacritinib combined with 5-azacitidine or decitabine. It records enrollment of 3 and a terminated status. Its primary efficacy outcome was ORR, defined around hematologic improvement and remission categories under IWG-2006 criteria.
What the record does not provide is an observed formal response result. It says the two participants who received study medication were not on study long enough for formal response assessment. As a result, the posted information does not establish a response rate, nor does it show that no response occurred. No ORR estimate, confidence interval, or efficacy comparison is reported.
The record also does not establish a comparative treatment effect. The design is single group, with allocation listed as not applicable and no like-for-like control. General statistical reasoning cannot substitute for a missing comparison or missing endpoint assessment. Conclusions about how outcomes differ from another treatment strategy are not supported by this design and these reported results.
The safety figures describe the recorded events in a very small group; they do not quantify a comparative risk or establish causation. The reported serious-event figures and pneumonia percentage should be read as registry descriptions, with no additional event detail or attribution available in the record.
Thus, the study’s registry entry documents its treatment plan, stated outcome, status, and limited safety reporting, but it does not provide a formal efficacy result. The record also does not report the statistical analysis plan, missing-data procedures, sample-size justification, or further details needed to reconstruct an analysis.
13. Why This Trial Matters Statistically
This study matters statistically because it illustrates the distinction between a trial’s stated question and the result that can actually be estimated from its posted record. The primary question concerned ORR, but formal response assessment was not completed for the participants who received medication. Without that assessment, a response proportion cannot be described from the posted results.
It also illustrates how design determines the kind of inference available. A single-group study can describe outcomes among participants when those outcomes are collected and reported. It cannot provide a randomized comparison with a separate control group. Here, the absence of a comparator and the absence of a formal response result are distinct limitations: resolving one would not automatically resolve the other.
The record highlights why denominators, analysis populations, and missing-outcome rules matter for a proportion endpoint. A reader needs to know who was included and how participants without an assessment were handled to interpret a response estimate. The registry does not report those details or an ORR estimate, so no analysis population can be reconstructed.
Finally, the study shows why planning calculations should be separated from observed evidence. Hypothetical sample-size illustrations under equal allocation between two arms do not describe the actual single-group design, and they are not observed power. The reported safety counts likewise remain descriptive, particularly with enrollment of 3 and no concurrent control. Clear distinction between recorded details, missing results, and general statistical principles prevents unsupported conclusions.
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 foremost limitation is that no formal primary response assessment is reported. The registry says the two participants who received medication were not on study long enough for formal assessment. It does not report an ORR estimate, category-specific outcomes, uncertainty interval, or efficacy analysis. The absence of these results means efficacy cannot be quantified from the registry record; it should not be interpreted as a zero response result.
Enrollment was 3, and the study was single group. The small enrollment limits the precision of any descriptive estimate, while the lack of a control group prevents a randomized comparison. The record’s safety counts therefore do not support a comparative estimate of adverse-event risk.
Further treatment and outcome details are incomplete. The regimen description ends mid-sentence during the dose description for the first cycle of combined therapy. The registry does not report how many participants reached combination treatment, which combination drug participants received, or which treatment each participant was taking when an adverse event occurred. The listed timeframe of 28 days is not further explained.
Statistical reporting is also limited. No analysis is listed, and the registry record does not report the statistical analysis plan, sample-size justification, interim analysis plan, missing-data methods, analysis populations, or response-assessment procedures beyond the stated criteria. The record reports that two participants were taken off study due to the full clinical hold, but does not supply a participant-level accounting of all outcome availability or a separate termination date. These omissions prevent independent reconstruction of the intended analysis and its results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pacritinib for Patients With Lower-Risk Myelodysplastic Syndromes (MDS) — NCT02469415.
- Registry record last updated 2018-10-16; status last verified 2018-05.
- Results first posted 2018-04-23.
- 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.
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18. Record Summary
NCT02469415 is a phase II, single-group study sponsored by M.D. Anderson Cancer Center, titled “Pacritinib for Patients With Lower-Risk Myelodysplastic Syndromes (MDS).” The registry lists enrollment of 3, no masking, a start date of 2015-09-30, a primary completion date of 2017-06-03, and terminated status.
The planned treatment began with pacritinib and was intended to proceed to pacritinib combined with 5-azacitidine or decitabine. The primary efficacy outcome was ORR under IWG-2006 response criteria. The registry says the participants who received medication were not on study long enough for formal response assessment, and it lists zero analyses.
The safety record lists 1 participant affected by a serious adverse event among 3 at risk, pneumonia at 33.3% as the top serious term, and 0 deaths. These are descriptive entries, not comparative estimates. The record does not report a formal efficacy result, a control group, or the statistical analysis and missing-data details needed to reconstruct an outcome analysis.