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 Cetuximab and Capecitabine in Treating Patients With Metastatic Colorectal Cancer That Failed Irinotecan Treatment (NCT00538291), a na phase 2 study. The primary outcome is Response Rate.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00538291 |
| Phase | Phase 2 |
| Condition | Colorectal Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | City of Hope Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Patients with metastatic colorectal cancer after prior treatment. The short title describes disease that failed irinotecan treatment, while the official title describes progression after previous fluoropyrimidine-containing therapy. The registry record does not reconcile these descriptions. The enrollment was 13.
Intervention
The study combined cetuximab with capecitabine. The registry describes cetuximab as an intravenous treatment and capecitabine as Xeloda, taken twice daily on days 1–14 of a 21-day cycle. Cetuximab was scheduled on day 1 and weekly thereafter.
Comparator
There was no comparison arm: the study model is single-group, allocation is listed as not applicable, and masking is listed as none. The registry therefore does not provide a concurrent control group for interpreting the treatment results.
Primary question
The primary endpoint was the number of participants with an overall tumor response, defined as complete response or partial response under RECIST v1.0. The endpoint was assessed after every 2 cycles of treatment, up to 1 year. The registry record does not report the response count or an estimate of response rate, so the endpoint’s observed result cannot be described from this record.
3. Trial Design
This was a Phase II, single-group study of cetuximab and capecitabine for metastatic colorectal cancer. The registry records enrollment of 13 and lists City of Hope Medical Center as sponsor. The study status is terminated. The reason for termination is not reported in the registry record.
The regimen description specifies cetuximab 400mg/m2 IV on day 1 over 2 hours, followed by 250 mg/m2 over 1 hour weekly, with Xeloda (capecitabine) 1000mg/m2 BID on days 1–14, repeated every 21 days. These are the schedule and doses described in the record; no further details about treatment modifications or adherence are reported.
Allocation is listed as not applicable, masking as none, and the study model as single-group. Thus, the trial does not make a randomized or masked comparison against another treatment or a control group. Its design can describe outcomes among participants treated in the study, but it cannot by itself separate treatment-associated outcomes from the natural course of disease, participant selection, or other influences.
The record lists gene expression analysis, microarray analysis, polymorphism analysis, reverse transcriptase-polymerase chain reaction, and immunohistochemistry staining among the interventions. Their specific analytic roles and results are not reported in the registry record. Study start is recorded as 2005-08 and primary completion as 2009-02. These dates do not establish the reason the study was terminated or whether all planned activities were completed.
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 | Arm 1 |
|---|---|
| STARTED | 13 |
| COMPLETED | 10 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Arm 1 |
|---|---|
| Adverse Event | 2 |
| Withdrawal by Subject | 1 |
Analysis population for the primary outcome, as defined in the registry: The three patients not completing at least two courses of treatment were considered treatment failures and were included in efficacy analysis.
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 | Arm 1 |
|---|---|---|
| Participants analysed | 13 | |
| Age, Continuous | years | 61 (23 to 77) |
| Sex: Female, Male: Female | Participants | 6 |
| Sex: Female, Male: Male | Participants | 7 |
| Region of Enrollment: United States | participants | 13 |
6. Primary Endpoint
The registry lists the primary outcome as Response Rate, measured over Assessment after every 2 cycles of treatment, up to 1 year..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | number of responding participants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled “Response Rate” and is expressed as the number of responding participants. Under the stated RECIST v1.0 definition, complete response means disappearance of all target lesions, while partial response means at least a 30% decrease in the sum of the longest diameters of target lesions. Overall response combines complete and partial responses. Assessment was scheduled after every 2 cycles of treatment, up to 1 year, using spiral CT scans.
This endpoint is used to describe whether measurable target lesions meet prespecified criteria for tumor shrinkage or disappearance. It reduces imaging findings to response categories that can be counted, while retaining a defined measurement rule. It does not, by itself, describe how long a response lasts, whether disease progresses later, or how participants feel or function. Those outcomes are not specified as primary endpoints in this record.
The registry states that the three patients who did not complete at least two courses of treatment were considered treatment failures and included in the efficacy analysis. However, the registry record does not report the number of responders, the resulting response estimate, or an uncertainty interval. The endpoint definition is therefore available, but its observed result is not.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically interpretable question: how many participants in a single-group study had a complete or partial response while receiving cetuximab and capecitabine? It defines how response was assessed, and it specifies that three participants who did not complete at least two courses were treated as failures and included in the efficacy analysis. These details describe the endpoint and a part of the analysis population.
The record does not give the primary response count or a response estimate. It also reports no analysis entries. Consequently, the posted registry information does not support a numerical description of the observed response result, its precision, or a test of a statistical hypothesis. A confidence interval, if reported, would communicate uncertainty around an estimate; without an estimate and its uncertainty measure, readers cannot judge how compatible the data are with different possible response frequencies.
The single-group design is important for interpretation. Even if an outcome estimate were available, there would be no concurrent control group to establish what would have happened to similar participants under another treatment or without the study regimen. A response observed during treatment would describe the study participants, but the design alone would not establish that the regimen caused the response or that outcomes differed from those under another approach.
The record’s safety information includes 4 participants affected by serious adverse events among 13 at risk, and 13 participants affected by other adverse events among 13 at risk. The listed serious-event terms and percentages are descriptive safety data. The listed percentages do not replace event counts or clarify whether participants experienced more than one event. The record’s death count is not reported in the registry record.
The study status is terminated, but no reason is given. The status should not be treated as evidence about efficacy, safety, feasibility, or data quality. The response result and termination reason remain unknown from the registry record; neither should be inferred from the design or safety listing.
9. Statistical Methods Explained
The outcome is a count of participants who meet the RECIST v1.0 definition of overall response. At the participant level, the classification is whether the criteria for complete response or partial response are met. At the group level, the primary outcome is the number classified as responders. A response proportion could be formed from a responder count and an analysis population, but the record does not report the responder count or a numerical response estimate. No new estimate can therefore be reconstructed from the information recorded.
What does the endpoint definition contribute?
A prespecified response rule helps make outcome classification more consistent. Here, the registry defines complete response as disappearance of all target lesions and partial response as at least a 30% decrease in the sum of the longest diameters of target lesions. Overall response is the combination of these categories. The stated imaging method is spiral CT, with assessment after every 2 cycles of treatment, up to 1 year. These details make the endpoint’s criteria and assessment schedule understandable, but they do not reveal how many participants met the criteria.
In general, a count outcome summarizes how many participants satisfy a stated condition. It does not convey the full pattern of individual measurements, and it can be hard to interpret without knowing the population included in the analysis. The registry says that three participants who did not complete at least two courses were treated as failures and included in efficacy analysis. It does not give the full efficacy denominator or a response count, so the registry’s operational rule cannot be used to recover the endpoint estimate.
How should uncertainty be understood?
In general, a confidence interval describes the statistical uncertainty around an estimated quantity under a specified method. A narrow interval indicates greater precision than a wide interval, but neither width nor location can be assessed without the actual estimate and interval. The registry record does not report a confidence interval for response, a standard error, or another measure of precision. It also does not report a p-value for the primary endpoint. The absence of those results means that readers cannot evaluate the response estimate’s precision or statistical compatibility with a particular benchmark.
The record lists zero analysis entries. This is distinct from the endpoint definition: an outcome can be defined in the record without a corresponding analysis result being posted there. It is not possible to tell from the record whether analyses were conducted but not posted, whether the analysis was incomplete, or whether another reason explains the absence of results.
What does the design permit?
In general, a single-group study estimates outcomes in participants receiving the study regimen, without a concurrent comparison group. It does not estimate a treatment contrast against a control group. Allocation is listed as not applicable, masking as none, and the model as single-group. Therefore, randomized between-group methods cannot be inferred as the basis for this trial’s primary analysis. A difference from a historical or external outcome would require a defined comparator and assumptions that are not reported in this record.
The registry’s sample-size framework describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. For time-to-event planning, the framework refers to total events; for other outcomes, it refers to participants per arm. These are planning assumptions, not a report of the trial’s own design justification. Their two-arm structure does not match the listed single-group study model. Numerical planning results, the observed effect used for them, and the trial’s own sample-size justification are not reported in the registry record. Such illustrations are not observed power and should not be read as evidence that the study had a particular ability to detect an effect.
General statistical methods also depend on the data structure and analysis population. For a response outcome, a complete account would identify how participants were classified, how missing assessments were handled, and how uncertainty was calculated. The registry supplies the failure classification for participants who did not complete at least two courses, but it does not state a broader missing-data procedure or an inferential method. It would be inappropriate to assign a method that is not named in the record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure: the number of participants with an overall response. It lists no analysis entries. The statistical plan, including any planned testing procedure, is not reported in the registry record. The record also does not say whether interim analyses were planned or conducted.
Multiplicity arises in general when several hypotheses or outcomes are tested and the interpretation does not account for the number of opportunities to find a result. Multiple laboratory and tissue-analysis procedures are listed as interventions, but the record does not describe their endpoints, hypotheses, or results. It is not possible to determine whether they were part of confirmatory testing, exploratory work, or another purpose. No multiplicity adjustment or strategy is reported in the registry record.
For missing data and analysis populations, the registry gives one specific rule: the three participants who did not complete at least two courses were considered treatment failures and included in efficacy analysis. It does not report the total analyzed for the primary endpoint, the number with missing response assessments, any additional exclusion rules, or a sensitivity analysis. The response count itself is not reported, so the effect of the stated failure rule on the result cannot be evaluated.
These omissions limit reproducibility and interpretation. A clearly defined endpoint is useful, but readers also need the analysis population, missing-data procedures, and statistical method to understand how an estimate was obtained. Those details are not reported in the registry record and should not be assumed.
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 |
|---|---|---|---|
| Arm 1 | 4 | 13 | 30.8% |
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 |
|---|---|
| Arm 1 | 13 of 13 |
Most frequent serious adverse event terms
| Event term | Organ system | Arm 1 |
|---|---|---|
| Diarrhea | Gastrointestinal disorders | 2 of 13 |
| Dehydration | Metabolism and nutrition disorders | 2 of 13 |
| Mucositis oral | Gastrointestinal disorders | 1 of 13 |
| Nausea | Gastrointestinal disorders | 1 of 13 |
| Vomiting | Gastrointestinal disorders | 1 of 13 |
| Death | General disorders | 1 of 13 |
| Penile infection | Infections and infestations | 1 of 13 |
| Leukocyte count decreased | Investigations | 1 of 13 |
| Anorexia | Metabolism and nutrition disorders | 1 of 13 |
| Serum phosphate decreased | Metabolism and nutrition disorders | 1 of 13 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Arm 1 |
|---|---|---|
| Fatigue | General disorders | 12 of 13 |
| Aspartate aminotransferase increased | Investigations | 11 of 13 |
| Hemoglobin decreased | Blood and lymphatic system disorders | 9 of 13 |
| Alkaline phosphatase increased | Investigations | 9 of 13 |
| Alanine aminotransferase increased | Investigations | 8 of 13 |
| Hand-and-foot syndrome | Skin and subcutaneous tissue disorders | 8 of 13 |
| Rash acneiform | Skin and subcutaneous tissue disorders | 7 of 13 |
| Leukocyte count decreased | Investigations | 5 of 13 |
| Edema limbs | General disorders | 4 of 13 |
| Hypoalbuminemia | Metabolism and nutrition disorders | 4 of 13 |
Serious events with the highest arm-level rate: diarrhea (15.4%), dehydration (15.4%), mucositis oral (7.7%), nausea (7.7%), vomiting (7.7%).
The safety record lists 13 participants at risk for serious adverse events and 4 affected. It also lists 13 participants at risk for other adverse events and 13 affected. These are participant-level counts in the registry listing; they are not a comparison between treatment groups because the study has a single group.
The serious adverse event terms with listed percentages are diarrhea, 15.4%; dehydration, 15.4%; mucositis oral, 7.7%; nausea, 7.7%; vomiting, 7.7%; and death, 7.7%. The registry does not report the death count in the separate deaths field. The appearance of “Death” as a listed serious-event term should therefore be read as a reported term and percentage, not as a substitute for a separately reported death count.
In general, adverse-event percentages describe the frequency recorded under the study’s reporting conventions. They do not establish whether events were caused by treatment. Several listed terms may occur in the same participant; the registry does not report participant-level overlap, event timing, severity details beyond the serious-event listing, or exposure-adjusted rates. With no control group, the listed safety figures do not provide a comparative risk estimate.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a Phase II, single-group study evaluated cetuximab with capecitabine in metastatic colorectal cancer and defined response using RECIST v1.0. It also documents a rule for the efficacy analysis: participants who did not complete at least two courses were considered treatment failures. These are useful details for understanding what the study intended to measure and how one group of participants was classified.
The record does not report the number of responders, a response estimate, or a confidence interval. It therefore does not show the magnitude or precision of the primary outcome. The safety listing describes affected participants and serious adverse-event terms, but it does not establish causation or compare the regimen with an alternative.
Even if the response result were available, a single-group study would not provide a randomized comparison. It could describe what occurred among enrolled participants, but it could not, on its own, show what outcomes would have occurred under a different treatment. The record also does not report the reason for termination, so termination cannot be interpreted as an efficacy or safety finding.
The distinctions matter: a defined endpoint is not the same as a reported endpoint result; an observed outcome is not automatically a causal treatment effect; and a planning illustration is not an observed trial finding. The registry information supports description of the design, endpoint criteria, treatment schedule, and listed safety data. It does not support a conclusion about the size of the response result, its precision, or comparative effects.
13. Why This Trial Matters Statistically
This trial illustrates why statistical interpretation begins with the design and the availability of results. The registry defines a response endpoint and specifies a rule for classifying participants who did not complete at least two courses. Yet it does not report the response count or an analysis result. Readers therefore cannot move from the endpoint definition to a numerical estimate of the outcome.
The single-group design is also central. A treatment outcome measured in one group is descriptive of that group; it is not a treatment contrast. Recognizing this prevents a response observation, if one were reported, from being mistaken for evidence of superiority over a comparator that was not part of the design.
The record further distinguishes safety counts from causal conclusions. It lists serious adverse events and other adverse events, but without a comparison group or additional detail, those counts describe what was recorded rather than the excess risk attributable to the regimen. The separately unreported death count reinforces the need to distinguish a listed event term from a complete outcome report.
Finally, the sample-size framework describes planning illustrations that assume equal allocation between two arms, while the study is listed as single-group. This makes it important to keep planning calculations separate from the trial’s actual design and from its observed results. In general, statistical quantities are informative only when their assumptions, data, and target comparison are clear. The registry record leaves several of those elements unavailable, so disciplined interpretation includes stating what cannot be estimated from it.
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 primary limitation for interpreting efficacy is that the registry defines response but does not report the response count, response estimate, or uncertainty interval. Although the record states that three participants who did not complete at least two courses were considered treatment failures and included in efficacy analysis, it does not provide the complete analysis denominator or the final efficacy result.
The study is single-group, with allocation listed as not applicable and masking as none. There is no concurrent comparator, so the design does not support a randomized estimate of comparative treatment effect. The record also gives two different descriptions of prior treatment context: the short title refers to failure of irinotecan treatment, while the official title refers to progression after previous fluoropyrimidine-containing therapy. The record does not explain the difference.
Safety interpretation is limited by the descriptive nature of the listings. The record reports affected participants and serious-event terms, but does not report participant-level overlap, event timing, or the death count in the separate deaths field. The reason for termination is not reported. The statistical analysis plan, interim-analysis information, sample-size justification, and broader missing-data procedures are also not reported in the registry record.
These limitations do not establish that analyses or information were unavailable to the investigators; they describe what is not reported in the registry record. No unreported result, method, or reason can be inferred from the study status or from the endpoint definition.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Cetuximab and Capecitabine in Treating Patients With Metastatic Colorectal Cancer That Failed Irinotecan Treatment — NCT00538291.
- Registry record last updated 2014-08-28; status last verified 2014-08.
- Results first posted 2014-08-28.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT00538291 is a Phase II, single-group study sponsored by City of Hope Medical Center, with enrollment of 13 and status listed as terminated. It studied cetuximab plus capecitabine in metastatic colorectal cancer. The record gives a RECIST v1.0 response endpoint and states that three participants who did not complete at least two courses were counted as treatment failures in efficacy analysis.
The registry lists 4 participants affected by serious adverse events and 13 affected by other adverse events. It lists serious-event terms and percentages, but the death count is not reported in the registry record. No primary response count or analysis result is reported. The reason for termination, statistical analysis plan, and sample-size justification are not reported in the registry record.