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 Study Evaluating The Effects Of Oprelvekin On Cardiac Repolarization In Subjects With Chemotherapy Induced Thrombocytopenia (NCT00886743), a na phase 2 study. The primary outcome is Time-matched Change From Baseline in Corrected QT Interval Using a Population-specific Correction Formula (QTcN).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00886743 |
| Phase | Phase 2 |
| Condition | Severe Thrombocytopenia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 19 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Adults with cancer who were at risk of severe thrombocytopenia after myelosuppressive chemotherapy. The registry record describes treatment intended to prevent severe low platelet counts. Further eligibility criteria and the characteristics of enrolled participants are not reported in the registry record.
Intervention
Open-label oprelvekin, described in the arm information as a subcutaneous injection once daily. The arm description gives a dose of 50 mg/kg, while the adverse-event group title gives 50 μg/kg. The registry record does not resolve this difference.
Comparator
There was no separate comparison group. The study is recorded as single-group, with allocation listed as NA and masking as none. Consequently, the study does not provide a randomized or controlled treatment comparison.
Primary question
The planned primary endpoint was time-matched change from baseline in QT interval corrected using a population-specific formula, QTcN, from postdose Day 1 to the end of treatment. The registry record says this correction was not done because the sponsor terminated the study prematurely.
The stated clinical and statistical focus was cardiac repolarization during oprelvekin treatment in people receiving chemotherapy that could suppress bone-marrow platelet production. Corrected QT measurements are used to account for heart-rate differences when assessing the interval between electrical events in the heart. The record lists QTcN as the primary measure and identifies QTc calculated by Bazett’s and Fridericia’s formulas as secondary outcomes.
The clinical question therefore has an important limitation: the intended primary QTcN analysis is unavailable. The record indicates that collected QT data corrected with Bazett’s and Fridericia’s formulas are presented as secondary outcome measures, but numerical results for those measures are not reported in the registry record available for this account. The study can be described in terms of its objective, design and reported adverse-event counts, but the planned primary question cannot be answered from the recorded outcome information.
3. Trial Design
NCT00886743 is listed as a Phase 2, single-group study of oprelvekin. It was open-label, with masking recorded as none and allocation listed as NA. The record reports enrollment of 19 and describes one oprelvekin treatment arm; there is no separate control or comparator arm. The study is therefore not a randomized comparison, and its design does not support a like-for-like estimate of treatment differences against a control group.
The brief summary describes adults with cancer taking chemotherapy that can block bone marrow from making platelets. Oprelvekin was to be administered to prevent severe low platelet counts, while the study’s purpose was to learn about its effects on the heart’s electrical cycle. The intervention is identified as oprelvekin, and the arm description specifies an open-label subcutaneous injection once daily. The dose is recorded inconsistently: the arm description says 50 mg/kg, while the adverse-event group title says 50 μg/kg. The registry record does not clarify which dose is correct.
The record lists a start date of 2009-09 and a primary completion date of 2015-12. Its status is terminated. The primary endpoint was time-matched change from baseline in QTcN, with a timeframe from postdose Day 1 to the end of treatment. The record explicitly states that this population-specific correction was not done because the sponsor terminated the study prematurely. It says that collected QT data corrected using Bazett’s and Fridericia’s formulas are presented as secondary outcomes.
There are five outcome measures listed, but the registry record does not provide numerical results for the QT outcomes in the information available for this account. The record also lists no analyses. Details such as the reasons for termination, recruitment progress, treatment duration for participants, and the protocol’s planned statistical methods are not reported in the registry record. The design and outcome information should therefore be read as a description of what was intended and recorded, not as a completed test of the primary endpoint.
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: A total of 45 participants were screened; of these, 19 received treatment.
Overall Study
| Stage | Oprelvekin, 50 μg/kg |
|---|---|
| STARTED | 19 |
| COMPLETED | 15 |
| NOT COMPLETED | 4 |
Reasons for not completing this period:
| Reason | Oprelvekin, 50 μg/kg |
|---|---|
| Adverse Event | 3 |
| Other | 1 |
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: All participants who had received at least 1 dose of oprelvekin.
| Characteristic | Unit | Oprelvekin, 50 μg/kg |
|---|---|---|
| Participants analysed | 19 | |
| Age, Continuous | Years | 49.5 (SD 9.60) |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 8 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 7 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 12 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race/Ethnicity, Customized: White | Participants | 17 |
| Race/Ethnicity, Customized: Black or African American | Participants | 2 |
| Weight | Kilograms | 76.9 (SD 25.7) |
| Body Mass Index | Kilograms/meters^2 | 26.7 (SD 7.9) |
6. Primary Endpoint
The registry lists the primary outcome as Time-matched Change From Baseline in Corrected QT Interval Using a Population-specific Correction Formula (QTcN), measured over Postdose Day 1 to end of treatment.
| 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 endpoint was time-matched change from baseline in corrected QT interval using a population-specific correction formula, QTcN. Its stated timeframe was postdose Day 1 to the end of treatment. The registry record says the sponsor terminated the study prematurely and this population-specific correction of QT was not done. As a result, the primary endpoint has no reported result in the registry record.
In general, the QT interval describes part of the heart’s electrical cycle as measured on an electrocardiogram. The interval varies with heart rate, so a correction formula is used to make measurements more comparable across different heart rates. A change from baseline focuses on how a participant’s measurement differs from their own starting value; time-matching means comparing measurements at corresponding times after dosing. These are general explanations of the endpoint concepts, not additional details about the trial’s analysis.
The endpoint’s relevance to the study objective is that it was intended to characterize cardiac repolarization during oprelvekin exposure. The registry record lists QTcB and QTcF outcomes using Bazett’s and Fridericia’s formulas as secondary measures, including threshold-based outcomes and time-matched changes. It states that collected QT data corrected with those formulas are presented as secondary outcome measures. However, the numerical findings for those outcomes are not reported in the registry record. The secondary measures therefore cannot substitute for a reported primary QTcN result, and no conclusion about the magnitude or precision of QT change can be drawn from the outcome descriptions alone.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the planned primary endpoint was not calculated. The registry record says the population-specific QT correction, QTcN, was not done because the sponsor terminated the study prematurely. Thus, the primary question about time-matched change from baseline in QTcN cannot be evaluated from a reported primary estimate, and there is no confidence interval or other precision measure for that endpoint in the registry record.
The study was a single-group, open-label Phase 2 study with enrollment of 19 and no separate comparator. Observations from a single group can describe what was recorded during that group’s treatment, but they do not by themselves identify what would have happened without treatment or under another treatment. Without a control group, changes over time cannot be separated from other influences on measurements. Open-label status also means masking was not used, as recorded, though the registry record does not describe any specific effect of this on measurement or reporting.
The record identifies Bazett’s and Fridericia’s corrected QT measures as secondary outcomes and says collected QT data corrected with these formulas are presented. The outcome descriptions include time-matched changes from baseline and QTc threshold categories. However, numerical secondary outcome results are not reported in the registry record available for this account. The listed outcome titles indicate what was assessed, not what was observed. In particular, the titles alone do not establish the number of participants who met a threshold, the size or direction of any change, or the uncertainty around an estimate.
The adverse-event information is descriptive. The record lists 1 participant with a serious adverse event and 14 with other adverse events in the oprelvekin group, with 19 at risk for each category. Sepsis is listed among the serious adverse-event terms at 5.3%. These figures do not establish that oprelvekin caused the events. With no comparator group, they cannot show whether the event experience differed from what would have occurred under another treatment or without treatment. The record does not state the basis for attributing an event to treatment.
There is also an unresolved dose inconsistency: the arm description gives 50 mg/kg, while the adverse-event group title gives 50 μg/kg. These should not be silently treated as interchangeable. The record does not clarify the discrepancy, so interpretation of the recorded intervention dose is uncertain.
Overall, the available information supports a description of the study design, intended endpoints, termination and recorded adverse-event counts. It does not support an estimate of the primary QTcN effect, a controlled safety comparison, or a conclusion about treatment efficacy. The registry record does not report reasons for termination or detailed analysis methods, which further limits interpretation of the incomplete outcome record.
9. Statistical Methods Explained
The statistical interpretation depends first on distinguishing a study objective from an analyzed endpoint. The primary objective was expressed through time-matched change from baseline in QTcN. The registry record explicitly says that this population-specific correction was not done after premature termination. An endpoint listed in a protocol or registry is not itself a result: a numerical estimate, its uncertainty and the analysis population are needed to interpret the observed data. Those primary-endpoint results are not reported in the registry record.
What QT correction means
In general, the QT interval changes with heart rate. Correcting QT means applying a formula intended to account for that relationship, so QT measurements obtained at differing heart rates can be compared more meaningfully. The trial’s primary endpoint specified a population-specific correction called QTcN. The record does not report the formula, its derivation, or the measurements needed to reproduce it. It says the QTcN correction was not performed. It also identifies Bazett’s and Fridericia’s formulas for secondary QTc outcomes. Different correction formulas can yield different corrected values, particularly when heart rate differs from the circumstances under which a formula performs well. That general consideration is one reason to distinguish the planned QTcN endpoint from the secondary QTcB and QTcF measures.
Change from baseline and time matching
In general, a change-from-baseline endpoint compares a participant’s later measurement with that participant’s own baseline measurement. This can account for stable differences between people, but it does not remove changes caused by time, concurrent conditions or other influences. A time-matched comparison aligns measurements at corresponding times after dosing. The primary endpoint was specified as time-matched change from baseline from postdose Day 1 to the end of treatment. The registry record does not provide numerical results or sufficient details about the measurement schedule and analysis to explain how such comparisons would have been constructed.
Why a single group limits causal interpretation
The study is recorded as single-group, open-label, with allocation listed as NA and no comparator arm. In general, a control group helps distinguish treatment-associated changes from changes that might occur over time for other reasons. Randomization, when used, supports comparability between groups by distributing known and unknown factors. Neither a randomized allocation nor a separate comparison group is recorded for this study. Consequently, even if a within-group change were reported, it could not be read as a controlled treatment effect. Masking is recorded as none; the registry record does not report whether knowledge of treatment influenced any measurement or assessment.
What the secondary outcomes can establish
The listed secondary measures include time-matched change from baseline in QTc using Bazett’s and Fridericia’s correction formulas, as well as counts of participants meeting specified QTc thresholds. In general, continuous change measures describe the magnitude and direction of measurements, while threshold outcomes classify whether a measurement or change crosses a prespecified boundary. Thresholds can be clinically or operationally useful, but categorization discards detail about how close a value is to the boundary and does not by itself describe uncertainty. The record states that QT data corrected using Bazett’s and Fridericia’s formulas are presented as secondary measures; their numerical findings are not reported in the registry record available for this account.
Precision and confidence intervals
In general, a confidence interval describes the range of values compatible with an estimate under the statistical model and sampling assumptions. Its width conveys precision: a narrower interval indicates greater precision, while a wider interval indicates more uncertainty. The registry record does not report an estimate or confidence interval for the primary QTcN endpoint because that correction was not done. Without numerical secondary results and their uncertainty measures in the record, precision cannot be assessed for those outcomes either. Enrollment of 19 is not enough by itself to determine precision; the endpoint variability, analysis method and actual observations are also needed.
Planning illustrations are not observed power
The record’s sample-size assumptions describe a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustrated effect is a stated fraction of the observed effect. For time-to-event outcomes, the planning convention refers to total events; for other outcomes, it refers to participants per arm. These are general planning assumptions, and the resulting sample-size illustrations are not observed power. They do not change the study’s actual single-group design or create a valid control comparison. The registry record does not report the underlying numerical planning estimates or the trial’s own sample-size justification.
The planning setup is also not a substitute for a completed analysis. A hypothetical two-arm planning calculation does not mean that two arms were enrolled, and it cannot repair the absence of the primary QTcN result. The registry record does not report the protocol’s statistical analysis plan, the handling of repeated measurements, or model details. No additional assumptions about these methods should be made.
Over-dispersion and count data
In general, over-dispersion occurs when count data vary more than a statistical model expects. If present, it can make standard errors too small and confidence intervals too narrow unless the model accounts for it. The registry record does not describe a count model for the adverse-event data, nor does it report a dispersion assessment. This concept is relevant generally to count analyses, but there is no basis to claim that over-dispersion was present or that a particular method was used in this study.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists five outcome measures, including a primary QTcN measure and secondary QTc outcomes based on Bazett’s and Fridericia’s formulas. It records no analyses. The primary population-specific QT correction was not done after premature termination, and numerical results for the listed secondary QT outcomes are not reported in the registry record available for this account.
When a study evaluates multiple outcomes, time points, formulas or thresholds, the chance of observing an apparently unusual result somewhere among those analyses can increase. Statistical methods for handling multiplicity can be prespecified to address that issue. The registry record does not report whether multiplicity was addressed, which outcomes were treated as confirmatory, or how any testing hierarchy was defined. No adjustment or unadjusted significance result should be inferred from the outcome titles.
The record does not describe missing-data methods, the number of missing measurements, or the analysis populations used for any outcome. The primary endpoint’s absence is specifically attributed to the QTcN correction not being done after termination; it should not be recast as an ordinary missing-value problem with an assumed remedy. The registry record also does not report whether participants with incomplete follow-up or measurements were included in any secondary analyses.
In general, missingness can affect interpretation when the likelihood of missing data is related to a participant’s health, treatment or observed measurements. Methods such as imputation or sensitivity analyses require information about the data and assumptions. None is reported. Accordingly, the available record does not establish how incomplete observations were handled or whether conclusions would be sensitive to missing data. These omissions matter because the intended primary analysis was not completed and the secondary numerical findings are not available in the registry information.
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 |
|---|---|---|---|
| Oprelvekin, 50 μg/kg | 1 | 19 | 5.3% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Oprelvekin, 50 μg/kg | 14 of 19 |
Most frequent serious adverse event terms
| Event term | Organ system | Oprelvekin, 50 μg/kg |
|---|---|---|
| Sepsis | Infections and infestations | 1 of 19 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Oprelvekin, 50 μg/kg |
|---|---|---|
| Dizziness | Nervous system disorders | 3 of 19 |
| Vision blurred | Eye disorders | 2 of 19 |
| Dehydration | Metabolism and nutrition disorders | 2 of 19 |
| Hypocalcaemia | Metabolism and nutrition disorders | 2 of 19 |
| Neutropenia | Blood and lymphatic system disorders | 1 of 19 |
| Thrombocytopenia | Blood and lymphatic system disorders | 1 of 19 |
| Atrioventricular block first degree | Cardiac disorders | 1 of 19 |
| Sinus bradycardia | Cardiac disorders | 1 of 19 |
| Sinus tachycardia | Cardiac disorders | 1 of 19 |
| Ocular hyperaemia | Eye disorders | 1 of 19 |
Serious events with the highest arm-level rate: sepsis (5.3%).
The adverse-event record lists 19 participants at risk for both the serious and other adverse-event categories. It records 1 participant with a serious adverse event and 14 with other adverse events. Sepsis appears among the serious adverse-event terms, reported as 5.3%. These are descriptive figures from the single oprelvekin group.
The figures should not be interpreted as evidence that oprelvekin caused an event or as a comparison with another treatment. The study has no separate control group, and the registry record does not report a treatment-attribution analysis. The entry for sepsis is a reported percentage, but the registry record does not specify its denominator in the information. It should not be used to infer an unreported count.
The adverse-event group title identifies oprelvekin as 50 μg/kg, whereas the arm description states 50 mg/kg once daily. The registry record does not reconcile these dose descriptions. The adverse-event figures therefore need to be read alongside this unresolved recording discrepancy. The record does not provide event timing, duration, severity detail beyond the serious-event classification, or an explanation of whether participants could contribute to more than one event category. These counts describe the recorded safety experience; they do not establish comparative risk.
12. What the Result Does, and Does Not, Mean
The registry record shows that NCT00886743 was designed to examine cardiac repolarization during oprelvekin treatment in adults with cancer receiving chemotherapy associated with severe thrombocytopenia. The intended primary measure was time-matched change from baseline in QTcN. The record says the sponsor terminated the study prematurely and the QTcN correction was not done. The principal planned endpoint therefore has no reported result in the registry record.
The record also names secondary outcomes using Bazett’s and Fridericia’s correction formulas, including changes from baseline and threshold-based QTc measures. It says collected QT data corrected by those formulas are presented as secondary outcomes, but numerical findings are not reported in the registry record available for this account. The outcome names alone do not indicate whether values increased or decreased, how many participants met a threshold, or how precise any estimate might be.
The study was open-label and single-group, with no comparator arm. It cannot provide a randomized estimate of the difference between oprelvekin and another treatment. General within-group observations, if available, would also be unable by themselves to separate treatment-associated changes from other influences. The record’s adverse-event counts describe events recorded in the treated group; they are not a controlled safety comparison and do not establish causation.
These limitations do not mean that the study had no statistical purpose or that its recorded observations are meaningless. They mean that the record supports a narrower account: the intended primary endpoint was not completed, the design lacked a control group, and the outcome information does not include numerical QT results. The adverse-event information can be described as reported, with care about its interpretation.
The registry record also leaves important context unresolved. It does not report the reason for termination, the analysis populations, missing-data handling, or the protocol’s detailed statistical plan. In addition, the dose differs between the arm description and the adverse-event group title. Those gaps limit reproducibility and make it especially important not to overstate what can be concluded from the study record.
13. Why This Trial Matters Statistically
This trial matters statistically because its intended primary endpoint and its available registry information diverge. QTcN was the planned primary measure, but the record says that this population-specific correction was not performed after premature termination. The distinction illustrates why an endpoint’s presence in a registry is not evidence that it was analyzed or that a result is available.
The record also makes clear why design matters when interpreting treatment observations. NCT00886743 was open-label and single-group, with no separate comparison arm. Such a design may describe measurements and adverse events among treated participants, but it cannot estimate a controlled difference between treatments. This is especially important when the study purpose concerns changes in a physiological measure that may also vary for reasons unrelated to treatment.
The trial additionally highlights the need to keep related outcomes distinct. QTcN was the planned primary correction, while Bazett’s and Fridericia’s corrections were listed for secondary outcomes. In general, different correction formulas are not interchangeable labels for the same calculated quantity. Reporting the formula, analysis and uncertainty for each outcome is necessary for readers to interpret what was measured. The numerical secondary results are not reported in the registry record available for this account.
Finally, the record includes adverse-event counts but no controlled safety comparison, and it contains inconsistent dose descriptions: 50 mg/kg in the arm description and 50 μg/kg in the adverse-event group title. These features show how design limitations and record-level inconsistencies can constrain interpretation independently of statistical calculations. A careful reading separates recorded details from unanswered questions rather than treating an incomplete outcome record as a definitive finding.
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 most important trial-specific limitation is that the primary QTcN endpoint was not performed. The registry record attributes this to premature termination by the sponsor. It does not report a primary estimate, confidence interval or other numerical result, so the planned primary analysis cannot be interpreted.
The study was single-group, open-label and had no comparator arm. It therefore cannot support a randomized treatment comparison. Enrollment was 19, but the registry record does not provide participant-level outcome data or numerical QT results for the listed secondary measures. The outcome titles alone cannot establish the direction, magnitude or precision of any QT change.
The stated dose is inconsistent across the record: the arm description says 50 mg/kg once daily, while the adverse-event group title says 50 μg/kg. No explanation or correction is reported. The reason for termination is also not reported in the registry record, beyond the statement that termination led to the primary correction not being done.
Other details needed to assess the analyses are not reported in the registry record. These include the statistical analysis plan, analysis populations, missing-data methods, measurement schedule details, and any approach to multiplicity. The record lists five outcome measures and no analyses, but does not provide a numerical account of the secondary QT findings in the information available for this account. The serious-event term sepsis is reported as 5.3%, without a stated denominator in the information. These limitations mean that neither the cardiac endpoint nor the safety figures can be interpreted as a controlled treatment effect.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study Evaluating The Effects Of Oprelvekin On Cardiac Repolarization In Subjects With Chemotherapy Induced Thrombocytopenia — NCT00886743.
- Registry record last updated 2017-04-19; status last verified 2017-03.
- Results first posted 2017-04-19.
- 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
NCT00886743 was a Phase 2, open-label, single-group study of oprelvekin in adults with cancer receiving chemotherapy associated with severe thrombocytopenia. Enrollment was 19. The registry record lists a start date of 2009-09, a primary completion date of 2015-12 and a status of terminated.
The planned primary endpoint was time-matched change from baseline in QTcN from postdose Day 1 to the end of treatment. The record says this correction was not done because the sponsor terminated the study prematurely. Bazett’s and Fridericia’s QTc measures are listed as secondary outcomes, but their numerical findings are not reported in the registry record available for this account.
The adverse-event record lists 1 participant with a serious adverse event and 14 with other adverse events, with 19 at risk for each category; sepsis is listed at 5.3%. The intervention dose is recorded inconsistently as 50 mg/kg in the arm description and 50 μg/kg in the adverse-event group title. The study had no comparator arm, and the registry record does not report the detailed statistical plan or the reason for termination.