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 Bevacizumab Plus Ixabepilone to Treat Patients With Advanced Kidney Cancer (NCT00923130), a na phase 2 study. The primary outcome is Progression-free Survival.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00923130 |
| Phase | Phase 2 |
| Condition | Renal Cell Carcinoma |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 30 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
People with relapsed or refractory metastatic renal cell carcinoma were the population named in the study objectives. The condition is recorded as renal cell carcinoma, and the enrollment is 30. The registry does not report the characteristics of the people enrolled or a more detailed description of the population included in the primary endpoint analysis.
Intervention
The study evaluated bevacizumab in combination with ixabepilone. The regimen description specifies bevacizumab 15mg/kg every 3 weeks and ixabepilone 6mg/m(2)/day on days 1,2,3,4 and 5 of each three week cycle.
Comparator
There was no comparator group: the registry records a single-group study with no masking. The regimen was not compared within this trial with either drug alone, another treatment, or a control condition.
Primary question
The primary endpoint is progression-free survival, defined as the time from the first day of treatment until disease progression under RECIST. The study objectives also include determining objective response rate, progression-free survival, and toxicity. Although the registry identifies progression-free survival as the primary endpoint, it does not report its median or 95% confidence interval. The record therefore states what the endpoint was intended to measure, but does not provide a numerical primary-endpoint result for interpretation.
3. Trial Design
This was a phase II, multi-center study of bevacizumab in combination with ixabepilone in subjects with advanced renal cell carcinoma. The registry classifies it as a single-group study, with allocation recorded as NA and masking as none. Its enrollment is 30, and its status is completed. The recorded start date is 2009-01-07 and the primary completion date is 2016-03-01.
The treatment description specifies bevacizumab 15mg/kg every 3 weeks and ixabepilone given on days 1,2,3,4 and 5 of each three week cycle at 6mg/m(2)/day. These are the regimen details recorded for the combination group. The record does not report how treatment changes, discontinuations, or adherence were handled in the analysis.
The primary endpoint was progression-free survival, with a stated timeframe of up to 44 months. The registry defines the measure as time from the first day of treatment to disease progression, defined according to RECIST. The objectives also name objective response rate and toxicity. Listed secondary outcomes include the number of participants with an objective response, the number with adverse events, the number who had biopsies, and overall survival.
Because this is a single-group study, it does not provide a randomized comparison between the combination and another treatment. Its design can describe outcomes observed in the treated group, but cannot by itself separate treatment effects from other explanations for those outcomes. The registry record does not report a statistical analysis plan, sample-size justification, interim-analysis plan, or a detailed analysis population. Those omissions limit what can be inferred about the planned statistical procedures and the precision or comparability of the reported analyses.
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
| Stage | Bevacizumab With Ixabepilone |
|---|---|
| STARTED | 30 |
| COMPLETED | 5 |
| NOT COMPLETED | 25 |
Reasons for not completing this period:
| Reason | Bevacizumab With Ixabepilone |
|---|---|
| Stopped treatment due to progression | 17 |
| Death | 1 |
| Discontinued treatment due to toxicities | 3 |
| Switched to alternative treatment | 2 |
| Refused further treatment | 2 |
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 | Bevacizumab With Ixabepilone |
|---|---|---|
| Participants analysed | 30 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 19 |
| Age, Categorical: >=65 years | Participants | 11 |
| Age, Continuous | years | 61.17 (SD 9.08) |
| Sex: Female, Male: Female | Participants | 7 |
| Sex: Female, Male: Male | Participants | 23 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 27 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 2 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 3 |
| Race (NIH/OMB): White | Participants | 26 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 30 |
| Prior Therapies | therapies | 2 (1 to 5) |
6. Primary Endpoint
The registry lists the primary outcome as Progression-free Survival, measured over up to 44 months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | months |
| Endpoint classification | Time-to-Event Analysis |
Progression-free survival is the primary endpoint. The registry defines it as the time from the first day of treatment to the day of disease progression. Progression is defined under RECIST as at least a 20% increase in the sum of the longest diameter of target lesions, using the smallest sum recorded since treatment started as the reference, or the appearance of one or more new lesions.
Time-to-event endpoints are used to describe how long it takes for an event of interest to occur. They can retain information about the timing of an event rather than reducing follow-up to a simple yes-or-no status. In general, some participants may not experience the event during the period observed. Their follow-up can be incomplete for the endpoint, a situation commonly handled through censoring in time-to-event methods. The registry does not describe how censoring was handled in this study.
The registry identifies the endpoint parameter as a median and names a 95% confidence interval as its measure of uncertainty. A median time-to-event estimate represents the point by which half of the analyzed group has experienced the event, under the applicable analysis method. A confidence interval conveys uncertainty about the estimate; it is not a range containing a known proportion of individual participants' event times.
The record gives the endpoint definition and timeframe of up to 44 months, but not the median estimate or its confidence interval. It therefore does not permit a numerical assessment of the observed progression-free survival or of its precision.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies progression-free survival as the primary endpoint and specifies how progression was defined. It does not report the median progression-free survival estimate or its 95% confidence interval. Without those results, the primary endpoint cannot be described numerically, and its precision cannot be assessed from the registry record.
The study enrolled 30 and evaluated one treatment group. That design can describe outcomes recorded for participants receiving the combination, but it does not estimate a randomized difference against a control group. Even if an outcome is observed in the treated group, a single-group result does not establish what would have happened to comparable participants under a different treatment or without the combination. The record lists no randomized control arm.
The study objectives include objective response rate, progression-free survival, and toxicity. The record also lists secondary outcomes such as objective response, adverse events, biopsies, and overall survival. However, the registry information available for this analysis does not give numerical response or survival results. Outcome names should not be mistaken for reported outcome findings.
The adverse-event summary includes a serious-event group with 30 at risk and 9 affected, and records 0 deaths. It lists six serious-event terms, each with a percentage of 3.3%. These entries describe the registry's safety summary; they do not establish whether events were caused by treatment, and the list should not be read as a complete account of all harms. The registry separately records 30 at risk and 30 affected for other adverse events, but does not provide further detail in the summary details used.
Statistical precision depends on the amount and pattern of endpoint information, not only on the enrollment figure. In general, confidence intervals help show how much uncertainty remains around an estimate. Since the primary result and interval are not reported, no conclusion about precision can be made for progression-free survival. Nor should the lack of a reported result be interpreted as evidence of no effect or no events.
The record describes a phase II study, but that label alone does not reveal the statistical decision rules used. The registry record does not report its sample-size justification, interim analyses, prespecified thresholds, or statistical analysis plan. The analysis should therefore remain limited to the study structure, endpoint definition, and safety summary that are actually recorded.
9. Statistical Methods Explained
What does a median time-to-event result represent?
The registry names a median as the primary endpoint parameter. In general, a median time-to-event estimate is the time at which the estimated event-free proportion reaches the midpoint of its distribution. It is a summary of the timing of events in the analyzed population, not a promise about the time any particular participant will experience progression. Its interpretation depends on the specified event definition, follow-up, and analysis method.
For this study, the event is progression under RECIST, and the clock starts on the first day of treatment. The record describes progression as at least a 20% increase in the sum of the longest diameter of target lesions, relative to the smallest sum recorded since treatment started, or the appearance of one or more new lesions. The registry does not report the median estimate, so the event-time summary cannot be interpreted numerically.
What does a confidence interval communicate?
The stated uncertainty measure is a 95% confidence interval. As a general statistical concept, a confidence interval represents uncertainty in an estimated quantity under the assumptions of the analysis procedure. A narrower interval generally indicates greater precision than a wider interval, while the location of the interval describes the range of values compatible with the data and method. It is not an interval for the outcomes of individual participants.
Because neither endpoint estimate nor confidence limits are reported, there is no interval to evaluate for width, location, or compatibility with a particular benchmark. The registry also does not give the method used to form the interval. No inference about whether it used a particular estimator or variance procedure should be made.
Why does follow-up matter for time-to-event analysis?
General time-to-event methods are designed for data in which participants can have different follow-up durations. Some may experience the event during observation, while others may leave observation or reach the end of follow-up without a recorded event. In many settings, those latter observations are treated as censored rather than as events at an assumed time. The amount and timing of follow-up, and the assumptions behind censoring, can affect the resulting estimate.
The registry states a timeframe of up to 44 months, but it does not report participant-level follow-up, the number of progression events, censoring details, or the method used to estimate the median. The timeframe alone does not establish how much follow-up was available for each participant or how many events contributed to the result.
Why does a single-group design affect interpretation?
General statistical interpretation distinguishes a within-group outcome description from a treatment comparison. With one group, the observed outcome can be summarized, but there is no concurrent randomized group in this trial to provide a like-for-like estimate under a different condition. Differences between treated participants and an external population, if someone were to make such a comparison, could reflect differences in participant characteristics, care, or follow-up rather than treatment. The registry record does not identify a control arm or a randomized comparison.
As a result, a response rate or time-to-event estimate, if reported, would characterize the study group under its design and analysis. It would not alone identify the causal contrast between the combination and another treatment. This limitation is distinct from uncertainty within the group estimate: a confidence interval can describe statistical precision without resolving the lack of a concurrent comparator.
How should the planning illustrations be understood?
The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It distinguishes time-to-event illustrations, which use a total event count, from other illustrations, which use participants per arm. These are planning assumptions, not descriptions of the single-group trial design. The trial itself is not a two-arm randomized comparison.
A sample-size illustration answers a hypothetical planning question under its assumptions. It is not an observed result, and it is not observed power. In general, power is a property of a design under an assumed effect and analysis procedure; calculating it after observing results does not establish the strength or reliability of the evidence. The registry does not report that these illustrations were the study's own design calculations, and their assumptions should not be attributed to the trial's protocol.
The registry record does not report the statistical analysis plan, the sample-size justification used for the study, or interim analyses. It also gives no sponsor-reported hazard-ratio values in the information available for this analysis. Consequently, no method, comparison, or numerical result beyond the recorded endpoint and safety summary should be inferred.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several study objectives and outcomes, including progression-free survival, objective response, toxicity, biopsies, and overall survival. When multiple outcomes or analyses are considered, multiplicity can matter: in general, examining multiple statistical questions can increase the chance of at least one apparently notable result unless the analysis plan addresses that issue. The registry record does not report whether multiplicity adjustments were planned or used, which outcomes were designated for formal hypothesis testing, or how any testing hierarchy was specified.
The record does not provide a statistical analysis plan or describe interim analyses. It therefore does not establish whether analyses were prespecified, whether any additional analyses were exploratory, or how decisions about analysis were made. These details are not reported in the registry record and should not be inferred from the outcome list.
Missing-data handling and analysis populations are also not described. The registry does not say which participants were included in the primary endpoint analysis, how participants without evaluable follow-up were handled, or how withdrawals and incomplete assessments were treated. For a time-to-event endpoint, follow-up that ends without a recorded progression may be handled through censoring in general, but the study-specific rules and assumptions are not reported.
The enrollment is 30, and the safety summary reports 30 at risk in each of its listed categories. Those figures do not establish the size of the primary endpoint analysis population. Without explicit analysis-population definitions and missing-data procedures, readers cannot determine from this record whether every enrolled participant contributed to each outcome or how incomplete information may have affected estimates.
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 |
|---|---|---|---|
| Bevacizumab With Ixabepilone | 9 | 30 | 30.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Bevacizumab With Ixabepilone | 0 of 30 |
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 |
|---|---|
| Bevacizumab With Ixabepilone | 30 of 30 |
Most frequent serious adverse event terms
| Event term | Organ system | Bevacizumab With Ixabepilone |
|---|---|---|
| Anemia | Blood and lymphatic system disorders | 1 of 30 |
| Cardiac arrest | Cardiac disorders | 1 of 30 |
| Cough | Respiratory, thoracic and mediastinal disorders | 1 of 30 |
| Enterocolitis infectious | Infections and infestations | 1 of 30 |
| Esophageal hemorrhage | Gastrointestinal disorders | 1 of 30 |
| Kidney infection | Infections and infestations | 1 of 30 |
| Lung infection | Infections and infestations | 1 of 30 |
| Presyncope | Infections and infestations | 1 of 30 |
| Urinary tract obstruction | Nervous system disorders | 1 of 30 |
| Diarrhea | Renal and urinary disorders | 1 of 30 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Bevacizumab With Ixabepilone |
|---|---|---|
| Anemia | Blood and lymphatic system disorders | 20 of 30 |
| Hypoalbuminemia | Metabolism and nutrition disorders | 20 of 30 |
| Creatinine increased | Investigations | 18 of 30 |
| Peripheral sensory neuropathy | Nervous system disorders | 18 of 30 |
| Lymphocyte count decreased | Investigations | 17 of 30 |
| Activated partial thromboplastin time prolonged | Investigations | 16 of 30 |
| Diarrhea | Gastrointestinal disorders | 16 of 30 |
| Hypertension | Vascular disorders | 16 of 30 |
| Hyponatremia | Metabolism and nutrition disorders | 15 of 30 |
| Nausea | Gastrointestinal disorders | 15 of 30 |
Serious events with the highest arm-level rate: anemia (3.3%), cardiac arrest (3.3%), cough (3.3%), enterocolitis infectious (3.3%), esophageal hemorrhage (3.3%).
The registry's serious-adverse-event summary records 30 at risk and 9 affected for the bevacizumab-with-ixabepilone group, with 0 deaths. It lists anemia, cardiac arrest, cough, infectious enterocolitis, esophageal hemorrhage, and kidney infection among the top serious-event terms; each is reported as 3.3%. These figures are the registry's recorded summary and should not be combined into a total or interpreted as mutually exclusive categories.
A percentage attached to an event term describes its frequency in the registry summary, but the record does not state the event counts for each term in the information used. A participant may also have more than one event, so event terms should not automatically be treated as separate people. The affected-participant figure and the event-term percentages answer different descriptive questions.
The record does not establish that every event was caused by the study treatment. It also does not provide event timing, severity detail beyond the serious-event classification, duration, resolution, or a comparison group. The separate adverse-event summary records 30 at risk and 30 affected, but the information does not give further detail about those events. These safety figures describe the registry entries; they do not by themselves support a causal comparison or a complete safety profile.
12. What the Result Does, and Does Not, Mean
This study's registry record establishes that a completed phase II, single-group study evaluated bevacizumab with ixabepilone in advanced renal cell carcinoma. It specifies the regimen, names progression-free survival as the primary endpoint, and defines progression under RECIST. It also provides a limited serious-adverse-event summary. These are useful elements for understanding what the study was designed to examine and what safety information is recorded.
The record does not report the primary endpoint's median or 95% confidence interval. It therefore does not show a numerical progression-free survival result or how precise such a result was. The outcome list includes response and overall survival, but the registry entries do not provide their numerical findings. Absence of a result in this record is not evidence that no events occurred, that an outcome was favorable, or that an outcome was unfavorable.
The single-group design also limits what a result could mean. A within-group outcome can describe what was observed among participants in that group, but it cannot serve as a randomized comparison against another treatment. The record does not provide a concurrent control group, and no causal treatment contrast can be estimated from the design as described.
In general, statistical estimates should be interpreted alongside their uncertainty, analysis population, follow-up, and assumptions. Here, the primary estimate, confidence interval, analysis details, and missing-data procedures are not reported in the registry record. The information does not support a conclusion about treatment benefit or lack of benefit. It supports a narrower reading: the study's design and endpoint are documented, while key numerical efficacy results and important analysis details are absent from this registry record.
13. Why This Trial Matters Statistically
This trial illustrates why identifying the design is essential before interpreting a clinical outcome. The registry records a single group and no masking, rather than a randomized comparison. That distinction determines the kinds of questions the study can answer: the design can describe outcomes in the treated group, but it cannot directly compare that group with a concurrent control arm.
The endpoint definition is also statistically important. Progression-free survival is a time-to-event measure, and the registry specifies both the start of follow-up and the RECIST progression criteria. Clear endpoint definitions help readers understand what counts as an event. But a definition is not a result: the record does not give the median progression-free survival estimate or its confidence interval.
The absence of those values shows why registry outcome labels should not be treated as evidence of an outcome. A record can name endpoints and list secondary measures without presenting the numerical findings needed to judge magnitude or precision. The record also omits details about the analysis plan, missing data, and analysis populations, which are relevant to assessing how an estimate was produced.
Finally, the safety summary illustrates the difference between a descriptive registry entry and a causal conclusion. It lists serious adverse-event information, but without a control group or further event details, it cannot establish comparative safety or attribute each event to treatment. Statistically, this study is informative about the design and measures planned, while the registry record leaves key efficacy results and analysis details unavailable.
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 main limitation for interpreting efficacy is that the registry record does not report the numerical primary endpoint result. Although progression-free survival is identified as the primary endpoint and a 95% confidence interval is named, neither the median nor its interval is given. The record also does not provide numerical results for objective response or overall survival in the information.
The study is single-group, with allocation recorded as NA and masking as none. It has no like-for-like randomized control comparison. Consequently, the design cannot establish a treatment contrast against another regimen. The record's enrollment of 30 does not, on its own, reveal how many participants contributed to each endpoint analysis.
Other limitations are the lack of reported detail about the statistical analysis plan, sample-size justification, interim analyses, missing-data handling, and analysis populations. The registry also does not provide the number of progression events, the follow-up distribution, or study-specific censoring procedures. These omissions prevent assessment of the assumptions and analysis choices underlying a time-to-event estimate.
The safety summary is limited to the recorded at-risk and affected figures, deaths, and listed serious-event terms. It does not provide event-level counts for those terms, timing, duration, resolution, or attribution. The percentages should therefore be read as registry descriptions, not as comparative or causal estimates. Together, these limitations mean that the available record supports a description of the study framework and selected safety entries, but not a full assessment of efficacy, precision, or comparative safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Bevacizumab Plus Ixabepilone to Treat Patients With Advanced Kidney Cancer — NCT00923130.
- Registry record last updated 2018-04-17; status last verified 2018-03.
- Results first posted 2017-06-27.
- 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
NCT00923130 is a completed phase II, multi-center, single-group study of bevacizumab plus ixabepilone in advanced renal cell carcinoma. The registry records enrollment of 30, no masking, and a primary completion date of 2016-03-01. The regimen description specifies bevacizumab 15mg/kg every 3 weeks and ixabepilone 6mg/m(2)/day on days 1,2,3,4 and 5 of each three week cycle.
Progression-free survival is the primary endpoint, defined from the first day of treatment to RECIST progression, with a timeframe of up to 44 months. The registry record does not report its median or 95% confidence interval. The safety summary records 9 affected among 30 at risk for serious adverse events and 0 deaths; six listed serious-event terms are each reported as 3.3%. The single-group design does not provide a randomized control comparison.