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 and Temozolomide Following Radiation and Chemotherapy for Newly Diagnosed Glioblastoma Multiforme (NCT00590681), a na phase 2 study. The primary outcome is Objective Response.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00590681 |
| Phase | Phase 2 |
| Condition | Glioblastoma Multiforme |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 62 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Chicago |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with newly diagnosed glioblastoma multiforme. The primary-outcome population is described as the 42 participants who proceeded to the post-radiation phase. The arm description refers to 48 subjects, while the registry enrollment is 62; the record does not explain the relationship between these figures or the reasons participants did not proceed to the post-radiation phase.
Intervention
The intervention is bevacizumab, also called Avastin in the registry summary, in combination with temozolomide. The study evaluates treatment following radiation and chemotherapy. The registry summary describes the study's aim as assessing whether adding Avastin during monthly cycles after radiation could affect tumor growth, tumor size, or survival. These are stated aims, not findings.
Comparator
There is no separate comparison group in the registry record. The trial is listed as single-group, with allocation recorded as not applicable. Consequently, the record does not provide a randomized or concurrent control group against which to compare outcomes.
Primary question
The primary outcome is objective response, expressed as a percentage of participants. The registry describes determining the best clinical response rate and obtaining a 95% confidence interval using the exact binomial distribution, with a timeframe of up to 3 years. The response estimate and its interval are not reported in the registry record, so the primary question cannot be answered from the posted results.
Statistically, this is a descriptive question about response among participants receiving the study treatment, rather than a direct estimate of how outcomes differ between treatment strategies. The registry also names safety, duration of response, overall survival, and changes in tumor relative cerebral blood volume after Avastin infusions as secondary outcomes. These outcomes address different aspects of the treatment experience and should not be treated as interchangeable with the primary response measure. The record states the study's motivation, but an objective or biological rationale does not establish that an outcome occurred.
3. Trial Design
The registry identifies this as a phase II study with a single-group model and no masking. Allocation is listed as not applicable, which is consistent with the absence of a separate randomized comparator in the record. The study status is completed. University of Chicago is listed as the sponsor; the brief summary separately says Genentech, Inc., the manufacturer of Avastin, sponsored the study. The record does not explain the relationship between these sponsor entries.
The intervention is named as bevacizumab and temozolomide. The arm description calls the study open-label and multi-center, and describes subjects with newly diagnosed supratentorial GBM. Its description is truncated, so it does not provide a complete account of the treatment schedule. The brief summary describes the addition of Avastin to temozolomide during monthly cycles following radiation. That wording conveys the study's intended treatment context, but the registry text does not give a complete protocol in the available description.
The record lists enrollment as 62. The arm description refers to 48 subjects, and the primary-outcome population is described as 42 participants who proceeded to the post-radiation phase. These are different reported figures with different descriptions. The record does not reconcile them, explain participant flow, or state whether the outcome population was determined before or after exclusions or missing observations.
The primary outcome is objective response, assessed as a percentage of participants, with a timeframe of up to 3 years. The registry says the best clinical response rates and 95% confidence intervals were to be obtained using the exact binomial distribution. It also lists safety, duration of response, overall survival, and changes in relative cerebral blood volume as secondary outcomes. Detailed outcome estimates are not reported in the registry record. A statistical analysis plan, including methods for handling missing outcomes or defining analysis populations beyond the stated primary population, is not reported in the registry record.
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 |
|---|---|
| STARTED | 62 |
| COMPLETED | 42 |
| NOT COMPLETED | 20 |
Reasons for not completing this period:
| Reason | Treatment |
|---|---|
| Withdrawal by Subject | 7 |
| Adverse Event | 8 |
| Death | 3 |
| Lost to Follow-up | 1 |
| disease progression | 1 |
Analysis population for the primary outcome, as defined in the registry: The forty-two participants did proceed to the post-RT phase.
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 |
|---|---|---|
| Participants analysed | 62 | |
| Age, Continuous | years | 60.4 (55.5 to 66.6) |
| Sex: Female, Male: Female | Participants | 19 |
| Sex: Female, Male: Male | Participants | 24 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 |
| Race (NIH/OMB): White | Participants | 56 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Objective Response, measured over Up to 3 years.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
Objective response is the primary endpoint. The registry defines the measure as a percentage of participants and says that the best clinical response rates were determined, with 95% confidence intervals obtained using the exact binomial distribution. The timeframe is up to 3 years. The primary-outcome population is described as the 42 participants who proceeded to the post-radiation phase.
In general, a response endpoint captures whether participants meet a clinical definition of tumor response during the specified assessment period. It can describe the frequency of response in the study population. The registry record does not give the response criteria, the assessment schedule, how response was confirmed, or how participants without an evaluable assessment were handled. Those details matter because they determine which observations count as responses and which participants contribute to the estimate.
A confidence interval communicates uncertainty around an estimated response percentage. It is not a guarantee that the true response frequency falls within the interval, but it indicates the range of values compatible with the observed data under the method's assumptions. The record names the exact binomial method, but does not report the response estimate or interval itself. Thus, neither the observed response frequency nor its precision can be assessed from the registry record.
Objective response is distinct from the secondary outcomes of response duration and overall survival. A response frequency does not, by itself, describe how long a response lasts or how long participants live. The registry lists those as separate outcomes, and their results are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question and design, but does not report the primary endpoint estimate. It names objective response as the primary outcome, specifies a percentage measure, an up-to-3-years timeframe, and an exact binomial confidence interval method. It does not give the number of responses, the response percentage, or the confidence interval. Therefore, the primary outcome's observed magnitude and precision cannot be evaluated from the posted results.
The record describes a single-group study. That design can report outcomes among participants who received the intervention, but it does not provide a concurrent comparison group. In general, without such a group, a measured outcome cannot by itself establish how much of the observed experience is attributable to the treatment rather than other influences. This is a design limitation, not a judgment about whether the intervention has an effect.
The reported study populations also need careful interpretation. The registry gives an enrollment of 62, the arm description refers to 48 subjects, and the primary-outcome population is described as 42 participants who proceeded to the post-radiation phase. The record does not explain these differences. The primary outcome is therefore specified for a narrower described population than the registry enrollment, and the available information does not permit reconstruction of participant flow or determination of the reasons for the different counts.
The registry lists several secondary outcomes, including safety, duration of response, overall survival, and tumor relative cerebral blood volume changes. These outcomes answer different questions. For example, response duration is not the same measure as the proportion of participants who respond, and survival is not inferred from response status. No estimates for these secondary outcomes are reported in the registry record.
The adverse-event information reports 3 participants with serious adverse events among 62 at risk and 53 with other adverse events among 62 at risk. It also lists anorexia, seizure, and thrombosis as serious-event terms, each at 1.6%. The registry does not report deaths in the adverse-event entry. These observations describe what was recorded; they do not establish a comparison of risk because the study has no listed control group. The record also does not clarify whether the participant counts in the serious and other event categories overlap.
Overall, the posted information is more complete about study intent and design than about efficacy outcomes. The absence of outcome estimates in the registry record should not be interpreted as evidence that there were no responses or no effects. It means that the response results cannot be determined from this record.
9. Statistical Methods Explained
What does a confidence interval communicate?
In general, a confidence interval expresses the uncertainty associated with an estimate. For a percentage such as a response rate, the estimate is based on the observed participants, while the interval communicates how much sampling uncertainty remains. A narrow interval indicates greater precision under the chosen method; a wide interval indicates less precision. Neither width nor placement can be assessed for this study because the registry record does not report the response estimate or its interval.
The registry specifies a 95% confidence interval. In general, the confidence level describes the long-run performance of a method across repeated applications under its assumptions. It is not a statement that an individual interval has a probability of containing the true value after it has been calculated. An interval also does not address every source of uncertainty: it does not, by itself, account for bias from participant selection, outcome measurement, missing data, or lack of a comparison group.
Why use an exact binomial method?
For a binary endpoint, each participant is classified into a response category, such as response or no response, according to the study's outcome definition. The response percentage is then estimated from the observed classification data. In general, the exact binomial method constructs an interval using the binomial probability model rather than relying on a normal approximation. This can be useful when the number of observations or the observed number of responses makes a normal approximation less reliable.
The registry says that the best clinical response rates and confidence intervals were obtained using the exact binomial distribution. It does not report the response count, the denominator used in the calculation, or the resulting interval. It also does not state the exact clinical criteria used to classify response. Knowing the method alone is not enough to recreate the estimate or judge how its assumptions applied to the observed data.
What can a single-group result establish?
In general, a single-group study estimates outcomes within the group receiving the intervention. It can describe the observed response frequency or adverse events in that study population. It does not directly estimate a treatment contrast against a control group when no such group is included. Randomized comparisons are designed to support a different kind of inference by comparing groups assigned to different strategies; this registry record lists no randomized comparison.
This distinction matters when interpreting apparent change over time or outcomes after treatment. Without a concurrent comparator, the record cannot separate treatment effects from other explanations, such as the natural course of the condition, differences in who enters the study, or other care received. These are general limitations of an uncontrolled design, not claims about what happened to participants in this study.
What do the sample-size assumptions mean?
The registry 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 says the effect to detect is a stated fraction of the observed effect. Such assumptions describe hypothetical planning calculations, not observed trial outcomes. Any sample sizes from those illustrations should be read as participants per arm for a specified power target, not as a measure of the power actually achieved in this single-group study.
In general, power calculations concern the chance that a study design would identify a specified effect under stated assumptions. They are not a substitute for reporting the observed estimate and its uncertainty, and they do not show that a result is true or clinically important. The registry's planning assumptions refer to an equal-allocation, two-arm setup, whereas the study design is listed as single-group. The record does not report that those planning assumptions were the trial's own design rationale. A sample-size justification for the trial is not reported in the registry record.
Why do analysis populations matter?
An analysis population determines which participants contribute to an endpoint estimate. The primary outcome is described for participants who proceeded to the post-radiation phase. The record also reports overall enrollment and an arm-description count that do not match that primary population. Without a participant-flow account or explicit rules for analysis inclusion, readers cannot determine why these figures differ or how the primary analysis treated participants without an outcome assessment.
General statistical practice distinguishes the population specified for an analysis from the wider group enrolled or treated. Different choices can change the denominator and can affect the interpretation of an estimate. The registry record does not provide enough detail to determine whether participants were excluded, had missing assessments, or were handled through another approach. These are unreported methods, not evidence that a particular procedure was or was not used in the full study.
Finally, statistical methods and numerical results are separate parts of an evidence record. The registry's description of an exact binomial interval method indicates how uncertainty was intended to be summarized, but without the estimate and interval, readers cannot assess the result's magnitude or precision. Similarly, the listed outcome names and timeframes do not substitute for outcome data. No analysis-specific results are reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists objective response as the primary outcome and names safety, duration of response, overall survival, and changes in relative cerebral blood volume after Avastin infusions as secondary outcomes. It also records six outcome measures. When a study evaluates multiple outcomes, there can be multiple opportunities for a result to appear statistically notable by chance. In general, a statistical plan may address this issue by specifying which outcomes are confirmatory and whether adjustment or a hierarchy will be used.
A multiplicity adjustment or outcome hierarchy is not reported in the registry record. The record also does not describe interim analyses, stopping rules, or a detailed statistical analysis plan. It is therefore not possible to determine how the investigators planned to interpret findings across the listed outcomes or whether any adjustment was used.
The primary-outcome population is described as the 42 participants who proceeded to the post-radiation phase. The registry enrollment is 62, while the arm description refers to 48 subjects. The record does not explain how these populations relate, identify reasons for non-inclusion in the primary analysis, or provide a participant-flow account.
Methods for missing outcome data are not reported in the registry record. It does not state how a participant without an evaluable response assessment would be classified, whether missingness was assessed, or whether any sensitivity analysis was conducted. These omissions limit interpretation of the endpoint denominator and the possibility of assessing how missing data could affect the response estimate. They should not be treated as evidence that missing data occurred or that a particular method was used.
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 | 3 | 62 | 4.8% |
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 | 53 of 62 |
Most frequent serious adverse event terms
| Event term | Organ system | Treatment |
|---|---|---|
| Anorexia | Metabolism and nutrition disorders | 1 of 62 |
| Seizure | Nervous system disorders | 1 of 62 |
| Thrombosis | Vascular disorders | 1 of 62 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Treatment |
|---|---|---|
| Fatigue | General disorders | 46 of 62 |
| Alopecia | Skin and subcutaneous tissue disorders | 34 of 62 |
| Nausea | Gastrointestinal disorders | 31 of 62 |
| Lymphopenia | Blood and lymphatic system disorders | 29 of 62 |
| Constipation | Gastrointestinal disorders | 27 of 62 |
| Hyperglycemia | Metabolism and nutrition disorders | 25 of 62 |
| Headache | Nervous system disorders | 24 of 62 |
| Platelets | Investigations | 22 of 62 |
| Pain | General disorders | 19 of 62 |
| Dermatology/Skin | Skin and subcutaneous tissue disorders | 18 of 62 |
Serious events with the highest arm-level rate: anorexia (1.6%), seizure (1.6%), thrombosis (1.6%).
The registry lists 62 participants at risk for serious adverse events and reports 3 participants affected. For other adverse events, it lists 62 at risk and 53 affected. The record does not say whether the participants in these categories overlap, so the counts should not be added or interpreted as separate groups of people.
The three serious-event terms listed are anorexia, seizure, and thrombosis, each reported as 1.6%. These are term-specific percentages in the registry entry. The record does not provide further detail about event severity beyond the serious-event classification, timing, duration, recurrence, or relationship to treatment. Deaths are not reported in the registry's adverse-event entry.
In general, adverse-event counts describe events recorded under the study's definitions and observation procedures. They do not by themselves establish that treatment caused an event. The study is listed as single-group, so there is no concurrent control group in the registry record for a comparative safety estimate. The adverse-event figures should therefore be read as descriptive reports from the study, not as evidence of a difference in risk between treatment strategies.
12. What the Result Does, and Does Not, Mean
The record gives a clear outline of the study's purpose and broad design: a phase II, open-label, single-group study of bevacizumab with temozolomide following radiation and chemotherapy for newly diagnosed glioblastoma multiforme. Objective response is designated as the primary outcome, with a stated percentage measure and an exact binomial confidence interval method. Safety and several other outcomes are also listed.
What the record does not provide is the primary response result. Without a response count, estimate, or confidence interval, it is not possible to describe the observed response frequency or how precisely it was estimated. The secondary outcome results are also not reported in the registry record. Their inclusion as planned outcomes should not be mistaken for evidence about what those outcomes showed.
The single-group design means the registry describes outcomes within participants receiving the intervention but does not report a randomized comparison. In general, a result from a single group does not by itself show what would have happened under a different treatment strategy. It therefore cannot establish a treatment contrast through the posted information alone.
The safety entry reports serious and other adverse-event counts and lists three serious-event terms. These data are descriptive; the record does not provide a control-group comparison or detailed event narratives. The listed percentages and counts should not be interpreted as a complete account of treatment safety.
Finally, the reported enrollment, arm-description count, and primary-outcome population are not reconciled in the registry record. This leaves uncertainty about participant flow and analysis inclusion. These limitations do not prove that the full study lacked additional analyses or reporting; they mark what cannot be established from the registry record. The result does not establish that the treatment works or does not work, because the relevant efficacy estimates are not reported.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between a clearly named endpoint and a reportable result. The registry identifies objective response, the measurement scale, the assessment timeframe, and an interval-estimation method. But without the response estimate and confidence interval, readers cannot evaluate either the observed frequency or its precision. A methods label alone does not convey the findings.
The design also illustrates why the analysis population needs to be explicit. Enrollment is reported as 62, the arm description refers to 48 subjects, and the primary-outcome population is described as 42 participants. These counts refer to different parts of the record, and their relationship is not explained. Statistical interpretation depends on knowing who contributed to an endpoint and why the analysis denominator differs from enrollment, when it does.
Multiplicity is another relevant issue because the registry names a primary outcome and several secondary outcomes. In general, testing or interpreting multiple outcomes requires care about the chance of highlighting findings that arise by chance. The registry does not report an adjustment strategy, analysis hierarchy, or detailed statistical plan, so readers cannot assess how that issue was handled.
Finally, the study is listed as single-group and open-label, with no registered comparator. This makes it important to distinguish descriptive outcomes from comparative treatment effects. The registry record supports an account of the question and methods described, but not a conclusion about comparative efficacy. That distinction is central to reading clinical trial results with appropriate statistical caution.
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.
Several trial-specific details that would help interpret the outcomes are not reported in the registry record. The response criteria and assessment procedures are not described in the primary-outcome entry. The record therefore does not show how clinical response was classified, how assessments were timed, or how participants without an evaluable response were treated in the analysis.
The population counts are not reconciled: enrollment is 62, the arm description refers to 48 subjects, and the primary-outcome population is 42 participants who proceeded to the post-radiation phase. The record does not explain participant flow, reasons for not proceeding, or whether all participants in the stated primary population had outcome data.
The registry reports no primary or secondary outcome estimates. As a result, the response frequency and its confidence interval cannot be assessed, and the listed duration-of-response, survival, safety, and relative cerebral blood volume outcomes cannot be interpreted beyond their stated names. A detailed statistical analysis plan, missing-data methods, multiplicity approach, and rationale for the trial's sample size are not reported in the registry record.
The design is single-group and open-label, with allocation listed as not applicable and no comparator group. This limits the ability to make comparative inferences from the record. The adverse-event entry is also limited: it lists counts and selected serious-event terms, but does not provide further event-level detail or a comparative safety analysis. These are limitations of the information available in the registry record; they do not establish what may have been reported elsewhere.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Bevacizumab and Temozolomide Following Radiation and Chemotherapy for Newly Diagnosed Glioblastoma Multiforme — NCT00590681.
- Registry record last updated 2021-03-30; status last verified 2021-03.
- Results first posted 2021-03-01.
- 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
NCT00590681 is listed as a completed phase II, open-label, single-group study of bevacizumab and temozolomide following radiation and chemotherapy for newly diagnosed glioblastoma multiforme. The registry lists University of Chicago as sponsor and enrollment as 62. The arm description calls the study multi-center and refers to 48 subjects; the primary-outcome population is described as 42 participants who proceeded to the post-radiation phase. The record does not reconcile these counts.
Objective response is the primary outcome, measured as a percentage of participants over up to 3 years, with a planned 95% confidence interval using the exact binomial distribution. Its numerical result is not reported in the registry record. Listed secondary outcomes include safety, duration of response, overall survival, and changes in tumor relative cerebral blood volume. The adverse-event entry reports 3 participants with serious events and 53 with other events, among 62 at risk in each category. No comparator group is listed, and detailed analysis methods are not reported in the registry record.