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 Gossypol in Treating Patients With Progressive or Recurrent Glioblastoma Multiforme (NCT00540722), a na phase 2 study. The primary outcome is Overall Survival.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00540722 |
| Phase | Phase 2 |
| Condition | Adult Giant Cell Glioblastoma, Adult Glioblastoma, Adult Gliosarcoma |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 56 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns patients with progressive or recurrent glioblastoma multiforme. The registry also lists adult giant cell glioblastoma, adult glioblastoma, adult gliosarcoma, and recurrent adult brain tumor among its conditions. The record does not provide a more detailed description of the primary-outcome population.
Intervention
Patients received oral R-(-)-gossypol acetic acid once daily on days 1-21. Treatment repeated every 28 days in the absence of disease progression or unacceptable toxicity. Tumor tissue and blood samples were collected at baseline and periodically during the study for laboratory biomarker analysis.
Comparator
The study was registered as a single-group trial, with allocation listed as NA and no masking. It therefore has no randomized control group in the registry record. The treatment experience is not a like-for-like comparison with another treatment arm.
Primary question
The primary endpoint was overall survival, expressed as median survival time with a 95% confidence interval. The registry describes estimating the overall failure rate and median survival using standard methods, over a timeframe of 4.5 years. The registry record does not report the median, its confidence interval, or an overall failure-rate estimate. It therefore does not permit a conclusion about the observed survival outcome from the recorded information alone.
3. Trial Design
This was a phase II study sponsored by the National Cancer Institute (NCI), registered as a single-group trial without masking. Allocation is listed as NA. The registry records enrollment of 56 and a completed status. The recorded start is 2008-01, and primary completion is recorded as 2012-06.
The treatment was oral R-(-)-gossypol acetic acid. Patients were scheduled to take it once daily on days 1-21, with treatment repeating every 28 days while disease progression or unacceptable toxicity had not occurred. The study also included laboratory biomarker analysis, with tumor tissue and blood samples collected at baseline and periodically during the study. The registry description of the biomarker sampling is truncated, so further details are not reported in the registry record.
The registered primary endpoint was overall survival, with median time and a 95% confidence interval specified. Secondary outcomes included the percent of patients with grade 3 and 4 adverse events related to treatment, tumor response rate, and progression-free survival rate defined by being alive and free from disease progression at 26-week (6 Months) from the first day of treatment. The registry lists five outcome measures, but outcome results for the endpoints are not included in the registry record recorded.
Because this was a single-group study, the design does not provide a randomized concurrent treatment comparison. The registry record does not report a control group, a randomization procedure, or masking. It also does not report a protocol rationale for the enrollment target or details of an analysis plan.
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 | Treatment (R-(-)-Gossypol Acetic Acid) |
|---|---|
| STARTED | 56 |
| COMPLETED | 56 |
| NOT COMPLETED | 0 |
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 | Treatment (R-(-)-Gossypol Acetic Acid) |
|---|---|---|
| Participants analysed | 56 | |
| Age, Continuous | years | 59 (34 to 79) |
| Sex: Female, Male: Female | Participants | 25 |
| Sex: Female, Male: Male | Participants | 31 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| 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 | 53 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Karnofsky Performance Status (KPS) | units on a scale | 80 (70 to 100) |
| Histology: Glioblastoma | Participants | 54 |
| Histology: Gliosarcoma | Participants | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Overall Survival, measured over 4.5 years.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | months |
| Endpoint classification | Time-to-Event Analysis |
Overall survival is the time from a specified starting point until death from any cause. It is used in clinical trials because it captures a direct time-to-event outcome and does not require classifying the cause of death as related to the disease or treatment. The registry identifies overall survival as the primary endpoint and specifies a median time with a 95% confidence interval over a timeframe of 4.5 years.
The median is the point in a time-to-event distribution at which the estimated proportion still alive has reached one half. It is a summary of the observed survival pattern, not a description of what happened to every participant. A confidence interval conveys statistical uncertainty around the estimate: a wider interval indicates less precision, while a narrower interval indicates greater precision, considered in context. The registry description also says that the overall failure rate would be estimated with 95% confidence intervals and that median survival would be estimated using standard methods, without naming the specific methods.
The registry record does not report a median overall survival estimate, its confidence interval, or the failure-rate estimate. Without those results, the endpoint’s observed value and precision cannot be assessed from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a completed phase II, single-group study of R-(-)-gossypol acetic acid, with enrollment of 56. Its primary question concerned overall survival. The treatment schedule and planned outcome definitions are recorded, but no primary-outcome estimate is reported in the registry record. In particular, the median survival time and its 95% confidence interval are not reported. The recorded study timeframe of 4.5 years is an endpoint timeframe, not a survival result.
This absence matters for interpretation. A study design and endpoint definition explain what investigators intended to evaluate; they do not establish what the observed data showed. No numerical estimate of survival, failure rate, tumor response, or progression-free survival is available in the registry entries. Accordingly, the registry record does not establish the direction, size, or precision of an outcome. It also does not support a treatment comparison, because the registered design is single-group and has no randomized comparator.
The safety information is limited to adverse-event affected counts and a list of serious adverse-event terms with percentages. The group record lists 6 in the serious adverse-event affected count and 28 in the other adverse-event affected count, each with 56 at risk. The serious terms include fatigue at 3.6%, Seizure at 1.8%, lleus at 1.8%, hypophosphatemia at 1.8%, and cardiac disorder other at 1.8%. These summaries are not a complete account of event timing, duration, severity distribution, or causal assessment. The registry record does not report a death count in this safety summary.
In general, a confidence interval helps readers distinguish an estimate’s central value from its uncertainty. Without the endpoint estimate and interval, precision cannot be discussed. In general, results from a single-group study describe outcomes among participants treated in that study, but do not by themselves separate treatment effects from other influences on outcomes. No sponsor-reported hazard ratio is stated in the registry record, and there is no randomized comparison for which a relative treatment effect could be interpreted.
The record also does not report analysis-population definitions, missing-data handling, interim analyses, or a multiplicity strategy. Those details can affect how endpoint results should be read, but their absence does not justify inferring a particular method or a favorable or unfavorable finding. The most defensible reading is therefore descriptive: the trial’s design and planned endpoints are recorded, while the primary outcome and several supporting results are not reported in the registry record.
9. Statistical Methods Explained
The registry identifies overall survival as the primary endpoint and describes estimating an overall failure rate with 95% confidence intervals, along with a median survival time using standard methods. It does not name the particular estimator, the time origin for survival, the censoring rules, or the handling of incomplete follow-up. Those choices are important for interpreting time-to-event outcomes, so they should not be presumed.
What does a median survival estimate mean?
In general, time-to-event data record how long it takes for an event to occur. For overall survival, the event is death from any cause. Some participants may not have experienced the event by the end of their observed follow-up. In time-to-event analysis, those observations are typically treated as censored: they contribute information up to the last time their status is known, without being treated as if the event occurred then. This is a general explanation, not a claim about the specific censoring methods used in this study. The censoring approach is not reported in the registry record.
A median survival estimate describes the midpoint of an estimated survival distribution. It is not the average follow-up time, and it does not mean that every participant had a duration near the median. Its interpretation depends on the follow-up and analysis methods. The registry record reports no median estimate, so neither its value nor its precision can be assessed.
How should a confidence interval be read?
In general, a confidence interval represents uncertainty in an estimate under the statistical procedure used. It is not a guarantee that the true value lies within the particular interval, and it does not show the distribution of individual outcomes. Its width reflects precision in context: estimates based on less information or more variable outcomes may be less precise. The registry specifies a 95% confidence interval for the primary endpoint but does not report the interval itself.
The record refers to an overall failure rate. In general, a failure rate in time-to-event work summarizes how quickly events accrue over observed time, subject to the model and assumptions used. The registry does not explain how this rate was defined or estimated, and it does not report an estimate. No further interpretation of that quantity is possible from the registry record.
What does the single-group design allow?
A single-group design can describe the outcomes observed among participants who received the study treatment. Without a concurrent control group, it cannot by itself show what would have happened to comparable participants under another treatment or without the study treatment. Differences between observed outcomes and an external expectation can be affected by patient selection, disease characteristics, follow-up, and other factors. This is a general limitation of uncontrolled comparisons, not evidence about the direction of any effect in this trial.
The registry lists allocation as NA and masking as none. There is no randomized treatment contrast in the record, so a randomized between-group estimate cannot be interpreted. The record does not report an adjusted or unadjusted hazard ratio for overall survival. The general statistical meaning of a hazard ratio is a comparison of event rates over time under a model; without a reported value and a suitable comparison, it provides no result to interpret for this trial.
How do the other outcomes fit in?
The registry lists tumor response rate and a progression-free survival rate defined as being alive and disease progression free at 26-week (6 Months) from the first day of treatment. It also lists the percent of patients with grade 3 and 4 adverse events related to treatment. These endpoints address different aspects of outcome and are not interchangeable with overall survival. For example, a response measure concerns tumor response, while a time-to-event endpoint concerns the timing of an event as defined by its protocol. The registry record does not provide results for these measures or the detailed analysis definitions needed to interpret them.
In general, time-to-event analyses must specify event definitions, the start of follow-up, censoring, and methods for estimating uncertainty. Binary outcome analyses require a definition of who is counted in the denominator and how missing outcome status is treated. These are general statistical considerations; the details for this trial are not reported in the registry record. The registry does not report a statistical analysis plan or named methods beyond its reference to standard methods for the primary endpoint.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several outcomes: overall survival as the primary endpoint, and secondary outcomes concerning grade 3 and 4 treatment-related adverse events, tumor response, and progression-free survival at 26-week (6 Months) from the first day of treatment. The registry also records five outcome measures. The available record does not include results for those endpoints beyond the safety summary described separately.
In general, examining multiple endpoints creates multiple opportunities to observe an apparently notable result by chance. A prespecified analysis plan may identify a primary endpoint, define the status of secondary endpoints, and specify whether any adjustment or testing hierarchy is used. The registry record does not report a multiplicity strategy, a testing hierarchy, or a statistical analysis plan. It is therefore not possible to determine whether any multiplicity adjustment was planned or applied.
The registry records zero analysis entries. That means no analysis results are recorded in the registry entries; it does not establish which analyses were performed outside the registry. Interim analyses and stopping rules are not reported in the registry record.
Missing-data methods and analysis populations are also not reported in the registry record. In general, time-to-event analyses need information about follow-up status and censoring, and other endpoint analyses need defined denominators and rules for missing outcomes. The registry records enrollment of 56 and safety at-risk counts of 56, but does not specify the primary-outcome analysis population, whether all enrolled participants were included in each endpoint analysis, or how missing observations were handled. No assumptions about these choices should be inferred from the enrollment or safety counts alone.
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 |
|---|---|---|---|
| Treatment (R-(-)-Gossypol Acetic Acid) | 6 | 56 | 10.7% |
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 |
|---|---|
| Treatment (R-(-)-Gossypol Acetic Acid) | 28 of 56 |
Most frequent serious adverse event terms
| Event term | Organ system | Treatment (R-(-)-Gossypol Acetic Acid) |
|---|---|---|
| fatigue | General disorders | 2 of 56 |
| Seizure | Nervous system disorders | 1 of 56 |
| lleus | Gastrointestinal disorders | 1 of 56 |
| hypophosphatemia | Metabolism and nutrition disorders | 1 of 56 |
| cardiac disorder other | Cardiac disorders | 1 of 56 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Treatment (R-(-)-Gossypol Acetic Acid) |
|---|---|---|
| fatigue | General disorders | 21 of 56 |
| vomiting | Gastrointestinal disorders | 4 of 56 |
| Rash maculo-papular | Skin and subcutaneous tissue disorders | 4 of 56 |
| peripheral sensory neuropathy | Nervous system disorders | 4 of 56 |
| constipation | Gastrointestinal disorders | 4 of 56 |
| diarrhea | Gastrointestinal disorders | 3 of 56 |
| anorexia | Metabolism and nutrition disorders | 3 of 56 |
Serious events with the highest arm-level rate: fatigue (3.6%), seizure (1.8%), lleus (1.8%), hypophosphatemia (1.8%), cardiac disorder other (1.8%).
The safety summary records 56 at risk for the treatment group. It lists 6 in the serious adverse-event affected count and 28 in the other adverse-event affected count. These are separate entries in the registry summary; they should not be added together or treated as a single total. The registry record does not explain whether participants could be represented in both categories, nor does it report event-level counts or timing.
The listed serious adverse-event terms and percentages are fatigue, 3.6%; Seizure, 1.8%; lleus, 1.8%; hypophosphatemia, 1.8%; and cardiac disorder other, 1.8%. The percentages are reproduced as recorded. The registry summary does not provide the denominators or further counting rules for these term-specific percentages, so they should not be converted into counts or directly compared without that context. The death count in the safety summary is not reported in the registry record.
In general, an adverse-event summary describes events recorded during a study; it does not alone establish that treatment caused them. The registry lists a secondary outcome concerning grade 3 and 4 adverse events related to treatment, but does not report its result. These safety figures therefore provide only a limited description of recorded adverse-event information.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed phase II study evaluated R-(-)-gossypol acetic acid in a single group of patients, with overall survival designated as the primary endpoint. It records enrollment of 56, the treatment schedule, a 4.5 years timeframe for the primary endpoint, and selected safety information. These are details about the study design and the information recorded, not a complete report of its clinical outcomes.
The primary survival result is not reported in the registry record. There is no median overall survival estimate, 95% confidence interval, or overall failure-rate estimate to interpret. The record also does not report tumor response or progression-free survival results. Consequently, it does not show how large or precise any outcome estimate was, or whether outcomes differed from an alternative treatment.
Because the trial was single-group, its design does not offer a randomized comparison. In general, an outcome observed after treatment in a single group cannot isolate the treatment’s contribution from other factors. That limitation remains even if an outcome estimate is available; in this record, the primary estimate itself is absent.
The serious and other adverse-event affected counts, along with the listed serious-event terms, are limited safety summaries. They do not provide a full account of how events were collected, their timing, the extent of follow-up, or the analysis of treatment relationship. The listed adverse-event figures should not be interpreted as a complete safety profile or as evidence of causation.
Overall, the registry information supports a description of the trial’s design, schedule, planned endpoints, and selected recorded safety counts. It does not support a conclusion about survival benefit, lack of benefit, tumor response, or comparative safety. Those conclusions require outcome information and, for a comparative treatment effect, an appropriate comparator and analysis.
13. Why This Trial Matters Statistically
This trial is statistically notable for the contrast between a clearly identified time-to-event primary endpoint and the absence of a reported primary-outcome estimate in the registry record. The endpoint is named, the median and 95% confidence interval are specified, and the timeframe is recorded as 4.5 years. Yet the median, interval, and failure-rate estimate are not reported. This illustrates why trial registration and outcome reporting serve different purposes: planned measurement does not substitute for observed results.
The single-group design also shapes what can be learned. In general, such a study can document outcomes in the treated group, but cannot provide a randomized estimate of how those outcomes compare with another treatment. Statistical interpretation depends not only on the size and precision of an estimate, but also on how the design supports causal comparison. Here, the registry records no randomized comparator.
The entry also illustrates the importance of analysis details for time-to-event endpoints. Follow-up definitions, censoring rules, the time origin, and the method for constructing confidence intervals all affect interpretation. The registry’s reference to standard methods does not identify those choices, and the results needed to assess precision are not reported.
Finally, the safety summary illustrates the difference between a selected set of adverse-event counts and a fully interpretable safety analysis. The counts and listed percentages are useful as recorded information, but their complete denominators, overlap, timing, and analysis context are not stated. Statistical reporting is strongest when outcome estimates, uncertainty, analysis populations, and definitions are available together. The gaps in this record limit how much can be concluded from its statistical information.
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 principal limitation for interpreting this trial from the registry record is that the primary endpoint result is absent. Although overall survival and its planned summary are identified, the median, 95% confidence interval, and failure-rate estimate are not reported. The secondary outcome results are also not reported in the registry record.
The single-group design has no randomized comparator in the registry. As a result, the record cannot support a randomized comparison of treatment outcomes. The absence of masking is recorded, but the record does not provide further detail on outcome assessment or any steps taken to limit assessment bias.
Several analysis details are not reported in the registry record, including the primary analysis population, missing-data handling, time origin, censoring rules, and the specific methods used to estimate survival and confidence intervals. The registry’s description of standard methods is not sufficiently detailed to identify these choices. A statistical analysis plan, interim analyses, stopping rules, and multiplicity strategy are also not reported.
The safety information is limited. The registry provides affected counts and selected serious-event terms with percentages, but does not report a death count in the safety summary or the complete context for the term-specific percentages. The record also does not provide event timing, duration, or detailed attribution information. The biomarker sampling description is truncated, limiting interpretation of that component. These limitations concern what is recorded; they should not be read as evidence that particular analyses or procedures were or were not conducted outside the registry.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Gossypol in Treating Patients With Progressive or Recurrent Glioblastoma Multiforme — NCT00540722.
- Registry record last updated 2017-08-11; status last verified 2017-07.
- Results first posted 2017-07-12.
- 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
NCT00540722 is a completed phase II, single-group study sponsored by the National Cancer Institute (NCI), with enrollment of 56. The registered treatment was oral R-(-)-gossypol acetic acid, taken once daily on days 1-21 and repeated every 28 days in the absence of disease progression or unacceptable toxicity. The primary endpoint was overall survival, summarized as median time with a 95% confidence interval over a timeframe of 4.5 years.
The registry record does not report the primary survival estimate or results for the listed tumor response and progression-free survival outcomes. Safety information includes 6 in the serious adverse-event affected count and 28 in the other adverse-event affected count, with 56 at risk. No death count is reported in the safety summary. The single-group design and missing outcome estimates limit interpretation of treatment effects and precision.