This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record.
1. Trial at a Glance
TRIBE was a phase 3 randomized parallel-group treatment trial sponsored by Gruppo Oncologico del Nord-Ovest evaluating combination chemotherapy strategies with bevacizumab in patients with colorectal cancer.
| Feature | TRIBE |
|---|---|
| Condition | Colorectal Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None |
| Primary purpose | Treatment |
| Start date | 2008-07 |
| Primary completion date | 2011-05 |
2. Clinical Question
Population
Patients with colorectal cancer enrolled in a first-line metastatic colorectal cancer treatment study.
Intervention
Bevacizumab combined with oxaliplatin, irinotecan, and infusional 5FU/LV (GONO FOLFOXIRI regimen).
Comparator
Bevacizumab combined with irinotecan and infusional 5FU/LV (FOLFIRI regimen).
Primary question
Does the FOLFOXIRI-based bevacizumab regimen improve progression-free survival compared with the FOLFIRI-based bevacizumab regimen?
3. Trial Design
Patients were allocated randomly.
Parallel-group phase 3 treatment comparison.
| Arm | Regimen |
|---|---|
| Experimental | Bevacizumab + oxaliplatin + irinotecan + infusional 5FU/LV (GONO FOLFOXIRI). |
| Comparator | Bevacizumab + irinotecan + infusional 5FU/LV (FOLFIRI). |
4. Primary Endpoint
| Endpoint | Definition | Time frame |
|---|---|---|
| Progression free survival | Compare progression free survival between bevacizumab with GONO FOLFOXIRI and bevacizumab with FOLFIRI. | Up to 54 months |
5. Statistical Methodology
The primary endpoint is progression-free survival, a time-to-event outcome. These endpoints are typically analyzed by methods that account for incomplete follow-up, because some participants may not have experienced progression or death at the time of analysis.
Time-to-event framework
Progression-free survival analysis generally estimates the distribution of time until progression or death while accounting for censored observations.
A randomized comparison of progression-free survival commonly uses Kaplan-Meier estimation to describe event-free probability over time and Cox proportional-hazards models to estimate relative treatment effects. The ClinicalTrials.gov record does not report the formal statistical analyses or results for this endpoint.
6. Planned Analysis
The registry identifies progression-free survival as the primary endpoint and describes the comparison between the two bevacizumab-containing chemotherapy strategies. No formal statistical analyses were posted to ClinicalTrials.gov.
For a progression-free survival endpoint, a typical analysis would compare time to progression or death between randomized groups using survival analysis methods. The interpretation would focus on the estimated difference between treatment strategies, uncertainty around that estimate, and assumptions underlying the survival model.
7. Statistical Methods Explained
Why is progression-free survival analyzed as a time-to-event endpoint?
Patients experience progression or death at different times. A time-to-event framework incorporates both event times and patients whose outcomes are not yet observed at analysis.
What does censoring mean in progression-free survival?
Censoring means that follow-up information ends before the event occurs. Proper statistical methods use available follow-up without assuming that censored patients experienced an event at the last observation time.
Why is randomization important?
Randomization helps create comparable treatment groups at baseline, reducing bias when comparing outcomes between treatment strategies.
Why is a hazard ratio often used for survival endpoints?
A hazard ratio summarizes the relative event rate between groups over the analyzed follow-up period. It does not directly represent the probability that an individual patient will experience an event.
Why are confidence intervals important?
Confidence intervals describe uncertainty around an estimated treatment effect and help distinguish precise estimates from those with substantial uncertainty.
8. Limitations
- The ClinicalTrials.gov record reports the study design and endpoint but does not report posted statistical analyses.
- Without posted results, treatment-effect estimates and uncertainty measures cannot be evaluated from the registry record.
- Progression-free survival analyses depend on event assessment procedures and censoring assumptions.
- Randomized trials estimate treatment effects within the enrolled study population and may not represent all clinical settings.
9. Why This Trial Matters Statistically
| Concept | How it appears in TRIBE |
|---|---|
| Randomization | Randomized phase 3 parallel-group comparison. |
| Time-to-event analysis | Primary endpoint was progression-free survival. |
| Comparative effectiveness | Two bevacizumab-containing chemotherapy strategies were compared. |
| Clinical trial design | Treatment allocation and endpoint definitions were prespecified in the registry. |