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
BRIM-3 was a randomized, parallel-group, open-label phase 3 trial evaluating vemurafenib versus dacarbazine in previously untreated patients with metastatic melanoma. The registry reports two primary time-to-event endpoints: overall survival and progression-free survival.
| Feature | BRIM-3 |
|---|---|
| Trial name | BRIM-3 |
| Phase | Phase 3 |
| Condition | Malignant melanoma |
| Population | Previously untreated patients with metastatic melanoma |
| Design | Randomized, parallel-group, open-label |
| Allocation | Randomized |
| Primary purpose | Treatment |
| Primary endpoints | Overall survival and progression-free survival |
| Primary endpoint type | Time-to-event |
| Enrollment | 675 |
| Status | Completed |
| ClinicalTrials.gov | NCT01006980 |
| Lead sponsor | Hoffmann-La Roche |
| Sponsor type | Industry |
2. Clinical Question
The central question was whether treatment with vemurafenib improved time-to-event outcomes compared with dacarbazine in previously untreated patients with metastatic melanoma.
Population
Previously untreated patients with metastatic melanoma.
Intervention
Vemurafenib.
Comparator
Dacarbazine.
Primary question
Does vemurafenib improve overall survival and progression-free survival relative to dacarbazine?
3. Trial Design
Vemurafenib
- Drug intervention
- Randomized treatment assignment
- Compared with dacarbazine for the primary time-to-event endpoints
Dacarbazine
- Drug comparator
- Randomized treatment assignment
- Reference group for the primary time-to-event comparisons
4. Trial Timing and Follow-Up
Trial initiated
The registry specifies that randomization was initiated in January 2010.
Primary completion
The registry lists December 2010 as the primary completion date.
Clinical cutoff
The primary endpoint time frames for overall survival and progression-free survival extend from randomization to December 30, 2010.
5. Primary Endpoints
| Endpoint | Registry definition | Time frame | Primary analysis |
|---|---|---|---|
| Overall Survival | An overall survival event was defined as death due to any cause. The number of participants with overall survival events is reported. | From randomization (initiated January 2010) to December 30, 2010. Median follow-up time in the vemurafenib group was 3.75. | Log-rank test; hazard ratio |
| Progression-free Survival | A progression-free survival event was defined as disease progression or death due to any cause. Tumor response (progression) was assessed according to RECIST version 1.1 criteria using CT scans or MRI. | From randomization (initiated January 2010) to December 30, 2010. | Log-rank test; hazard ratio |
Both primary endpoints are time-to-event endpoints. This is important statistically because participants can have different follow-up times, and some may be censored before experiencing the event. The registry identifies the hypothesis type for both primary analyses as superiority.
6. Statistical Methodology
Log-rank test
The registry reports the log-rank test for both primary endpoints. The log-rank framework compares the observed and expected pattern of events between randomized treatment groups over follow-up, making it appropriate for comparing time-to-event distributions.
For a superiority analysis, evidence against the null hypothesis is evaluated using the prespecified statistical framework. The reported BRIM-3 analyses provide both a hazard ratio and a P-value, allowing the statistical evidence to be considered alongside the magnitude and precision of the estimated treatment effect.
Hazard ratio
The effect measure reported for both primary endpoints was the hazard ratio (HR). The HR compares the estimated instantaneous event rate between treatment groups within the time-to-event modeling framework.
An HR of 0.37 for overall survival, for example, corresponds to an estimated hazard approximately 37% as large in the vemurafenib group relative to the dacarbazine group. Expressed as a relative reduction in estimated hazard, 1 − 0.37 = 0.63, or 63%. This is a statement about the estimated hazard ratio, not a statement that 63% of participants survived or that every participant experienced a 63% reduction in risk.
Intention-to-treat analysis
The registry defines the ITT population for the overall-survival analysis as all randomized participants, whether or not study treatment was received, with participants analyzed according to the treatment assigned at randomization. This preserves the treatment comparison created by randomization.
Stratified analysis
The statistical-analysis record identifies stratified analysis as an analysis concept for overall survival and for the broader statistical methodology. The ClinicalTrials.gov record does not provide the specific stratification variables in the complete analysis text, so this page does not infer or add them.
PFS analysis population
Cox regression for PFS
For progression-free survival, the registry specifically states that hazard ratios for treatment with vemurafenib compared with dacarbazine were estimated using unstratified Cox regression. This is distinct from the registry's separate identification of stratified analysis as an analysis concept.
7. Overall Survival Results
The registry reports a formal primary-endpoint analysis comparing vemurafenib with dacarbazine using the log-rank test and a hazard ratio. The analysis population was the ITT population as defined in the registry.
Hazard ratio for death
95% CI: 0.26–0.55 · P < 0.0001
Two-sided 95% confidence interval · Superiority hypothesis
The reported HR of 0.37 means that the estimated instantaneous rate of death under the fitted time-to-event analysis was 37% of the corresponding rate in the dacarbazine group. Equivalently, the estimated hazard was 63% lower for vemurafenib relative to dacarbazine.
The HR does not mean that 63% of participants avoided death, that 63% of participants benefited, or that an individual patient's probability of death was reduced by exactly 63%.
The 95% CI of 0.26–0.55 describes statistical uncertainty around the estimated hazard ratio. It is an interval for the treatment-effect estimate under the analysis framework, not a range containing the effects experienced by individual participants.
The P < 0.0001 value addresses evidence against the relevant null hypothesis under the specified testing framework. It does not measure the size of the treatment effect. Effect size is conveyed by the HR, while precision is conveyed by the confidence interval.
Because this is a time-to-event analysis, interpretation also depends on censoring and on the assumptions underlying the hazard-based model. A single HR is a relative summary of event rates over follow-up rather than a complete description of the survival experience at every time point.
Prespecified design assumptions
The registry states that the trial had 80% power to detect a hazard ratio of 0.65 for overall survival with an alpha level of 0.045. The design specified an increase in median survival from 8 months for dacarbazine to 12.3 months for vemurafenib. The registry also reports one interim analysis for overall survival at 50% information.
Design target
The planned detectable overall-survival hazard ratio was 0.65, with 80% power and an alpha level of 0.045.
Interim look
One interim analysis for overall survival was planned at 50% information.
8. Progression-Free Survival Results
The second primary endpoint was progression-free survival. A PFS event was defined as disease progression or death due to any cause, with progression assessed using RECIST version 1.1 criteria based on CT scans or MRI.
Hazard ratio for progression or death
95% CI: 0.20–0.33 · P < .0001
Two-sided 95% confidence interval · Superiority hypothesis
The reported HR of 0.26 means that the estimated instantaneous rate of progression or death under the fitted analysis was 26% of the corresponding rate in the dacarbazine group. Expressed as a relative reduction in estimated hazard, 1 − 0.26 = 0.74, or 74%.
That interpretation should not be translated into a claim that 74% of patients were protected from progression or death. A hazard ratio is a relative time-to-event measure, not a percentage of patients who benefit.
The 95% CI of 0.20–0.33 quantifies uncertainty around the estimated HR. Its relatively narrow span compared with the point estimate indicates that the reported estimate is accompanied by a defined range of statistical uncertainty under the stated model and sampling framework.
The P < .0001 value measures evidence against the null hypothesis within the specified testing framework; it is not an estimate of effect magnitude or clinical importance.
For PFS specifically, the registry states that treatment hazard ratios were estimated using unstratified Cox regression. Interpretation therefore depends on the Cox model and on the handling of censoring and event times.
Prespecified PFS design
The registry states that the trial had 90% power to detect a hazard ratio of 0.55 for progression-free survival with an alpha level of 0.005. The design description gives an increase in median survival from 2.5 months for dacarbazine to 4.5 months for vemurafenib.
9. Primary Results Side by Side
| Primary endpoint | Effect measure | Estimate | 95% CI | P-value | Hypothesis |
|---|---|---|---|---|---|
| Overall Survival | Hazard ratio | 0.37 | 0.26–0.55 | <0.0001 | Superiority |
| Progression-free Survival | Hazard ratio | 0.26 | 0.20–0.33 | <.0001 | Superiority |
Both reported primary analyses produced hazard ratios below 1, with two-sided 95% confidence intervals entirely below 1 and very small reported P-values. Statistically, the two endpoints therefore tell a consistent story within the reported analysis framework: the estimated event hazard was lower in the vemurafenib group for both death and progression or death.
The two endpoints nevertheless represent different clinical events. Overall survival counts death from any cause, whereas progression-free survival counts either disease progression or death. A treatment can affect these endpoints differently because progression is an earlier event and because some participants can experience progression without immediately experiencing death.
10. Safety: Serious Adverse Events
The ClinicalTrials.gov record reports serious adverse events by treatment arm. These figures should be interpreted as safety counts using the affected/at-risk denominators provided in the registry record.
| Safety group | Affected | At risk | Reported ratio |
|---|---|---|---|
| Vemurafenib | 165 | 336 | 165/336 |
| Dacarbazine | 52 | 293 | 52/293 |
| Vemurafenib after crossover | 44 | 84 | 44/84 |
The crossover category is reported separately in the ClinicalTrials.gov record. It should not be combined with the randomized vemurafenib and dacarbazine groups when describing the primary randomized safety comparison.
11. Interim Analysis and Alpha Spending
Interim monitoring is an important component of the BRIM-3 statistical design. The registry states that the trial included one interim analysis for overall survival at 50% information.
Why conduct an interim analysis?
An interim analysis permits evaluation of accumulating trial information before all planned information has been collected. This can be useful in a time-to-event trial where events accumulate over calendar time.
Why alpha matters
Repeatedly examining accumulating efficacy data can alter the probability of a false-positive conclusion. A prespecified alpha framework is therefore part of the design of a group-sequential trial.
The registry reports different alpha levels for the two primary endpoint designs: 0.045 for the overall-survival power calculation and 0.005 for the progression-free-survival power calculation. These values should be understood as elements of the prespecified design rather than as generic P-value thresholds to be applied retrospectively.
12. Intention-to-Treat Analysis
The registry explicitly defines the overall-survival ITT population as all randomized participants, whether or not study treatment was received. Participants were analyzed according to the treatment assigned at randomization.
The main statistical advantage is preservation of the treatment comparison generated by randomization. Treatment discontinuation, deviations from assigned therapy, or subsequent treatment can occur after randomization, but the ITT framework retains participants in their originally assigned groups for the primary efficacy comparison.
For PFS, the registry defines a more specific analysis population consisting of ITT participants randomized by October 27, 2010, at least 9 weeks before the December 30, 2010 cutoff. That distinction matters because an analysis population is part of the definition of the reported estimate.
13. Statistical Methods Explained
Why was a log-rank test used?
Overall survival and progression-free survival are time-to-event outcomes. Participants can be followed for different lengths of time, and some may be censored before experiencing the event. The log-rank test is designed to compare survival distributions while incorporating the timing of events and censoring rather than reducing every participant to a simple binary outcome.
What does an overall-survival HR of 0.37 mean?
Within the reported time-to-event analysis, the estimated instantaneous rate of death in the vemurafenib group was 0.37 times that in the dacarbazine group. This corresponds to a 63% lower estimated hazard. It does not mean that 63% of patients survived or that every patient had the same reduction in individual risk.
What does the 95% CI of 0.26–0.55 tell us?
The confidence interval describes uncertainty around the estimated HR. It gives a statistical interval for the underlying treatment-effect parameter under the specified model and sampling framework. It is not a range of individual patient outcomes and does not mean that future patients' hazards will necessarily fall inside the interval.
Why does the P-value not measure effect size?
A P-value describes the degree of statistical evidence against a null hypothesis under the specified testing framework. It is affected by both the magnitude of an observed effect and the amount of information available. The HR communicates relative effect magnitude, while the confidence interval communicates precision.
Why are OS and PFS analyzed separately?
OS and PFS are different endpoints. An OS event is death from any cause. A PFS event is disease progression or death from any cause, with progression assessed according to RECIST version 1.1 using CT or MRI. Their event definitions, timing, and censoring patterns can therefore differ.
Why does the ITT definition matter?
The ITT approach keeps randomized participants in their assigned treatment groups for efficacy analysis. This maintains the treatment comparison created by randomization and avoids redefining the comparison based on treatment received after randomization.
Why does the interim analysis affect interpretation?
Because the trial included an interim overall-survival analysis at 50% information, the inferential framework has to account for that planned look at the data. The design's alpha level and interim-analysis structure are therefore relevant when interpreting the statistical evidence rather than treating the reported P-value as an isolated number.
14. Understanding the Two Primary Hazard Ratios
| Feature | Overall Survival | Progression-free Survival |
|---|---|---|
| Event | Death due to any cause | Disease progression or death due to any cause |
| Effect measure | Hazard ratio | Hazard ratio |
| Estimate | 0.37 | 0.26 |
| 95% CI | 0.26–0.55 | 0.20–0.33 |
| P-value | <0.0001 | <.0001 |
| Analysis method | Log-rank test | Log-rank test |
| Additional model information | Registry identifies stratified analysis as an analysis concept | Unstratified Cox regression used to estimate HR |
The HR estimates are not interchangeable. An OS HR summarizes the relative death hazard, while a PFS HR summarizes the relative hazard of either progression or death. The smaller PFS HR therefore should not be described as proof that the treatment effect on death itself was larger than the OS effect.
15. Censoring and Time-to-Event Interpretation
Time-to-event analyses are designed for settings in which not every participant experiences the event during the observation period. A participant who has not experienced the specified event by the time their usable follow-up ends can contribute information up to the censoring time.
where di is the number of events at time ti and ni is the number at risk immediately before that time.
The registry-reported BRIM-3 registry data do not provide the underlying participant-level event and censoring times. Consequently, this page does not construct a Kaplan-Meier curve or attempt to reconstruct medians from the reported hazard ratios.
16. Limitations
- Summary-level data: the ClinicalTrials.gov record provides primary endpoint hazard ratios, confidence intervals, and P-values, but not the underlying participant-level time-to-event data.
- No reconstructed survival curves: without event and censoring times, the underlying Kaplan-Meier curves cannot be validly reconstructed from the ClinicalTrials.gov record.
- Analysis-population differences: overall survival uses the registry-defined ITT population, while PFS uses ITT participants randomized by October 27, 2010, at least 9 weeks before the clinical cutoff.
- Open-label design: masking is listed as none. This is relevant when considering outcomes that involve assessment procedures or treatment management, although the registry-reported primary analyses are time-to-event comparisons.
- Hazard-ratio interpretation: an HR is a relative time-to-event measure and should not be translated directly into an absolute probability difference or percentage of patients benefiting.
- Model dependence: the PFS HR was estimated using unstratified Cox regression. Cox-model interpretation depends on the model specification and time-to-event assumptions.
- Interim analysis: overall survival included a planned interim analysis at 50% information, making the prespecified monitoring framework relevant to inference.
- Safety scope: the ClinicalTrials.gov record contains serious adverse-event counts by arm but do not provide a complete safety profile.
17. Why This Trial Matters Statistically
BRIM-3 is a useful teaching case because it combines randomized treatment assignment with two clinically distinct time-to-event endpoints and a prespecified interim analysis. The trial also illustrates why a statistical result should be read as a package rather than as a single P-value.
| Concept | How it appears in BRIM-3 |
|---|---|
| Randomization | Participants were randomized to vemurafenib or dacarbazine. |
| Parallel design | The registry identifies a parallel-group design with two arms. |
| Open-label treatment | Masking is listed as none. |
| ITT analysis | Overall survival was analyzed using the registry-defined ITT population. |
| Time-to-event endpoints | Overall survival and progression-free survival were both primary endpoints. |
| Log-rank test | Reported as the primary comparison method for both endpoints. |
| Hazard ratio | Reported as the effect measure for both primary endpoints. |
| Confidence interval | Two-sided 95% CIs were reported for both primary HR estimates. |
| Interim analysis | One overall-survival interim analysis was planned at 50% information. |
| Stratified analysis | Identified as an analysis concept in the registry's statistical-analysis record. |
| Cox regression | Unstratified Cox regression was used to estimate the PFS hazard ratio. |
| Safety by arm | Serious adverse events were reported using affected/at-risk counts. |
18. What the Hazard Ratio Does — and Does Not — Mean
An HR of 0.37 means that, under the reported time-to-event analysis, the estimated instantaneous rate of death for vemurafenib was 37% of that for dacarbazine. The corresponding relative reduction in estimated hazard is 63%.
It does not mean that 63% of participants were cured, that 63% of participants avoided death, or that every individual patient had exactly a 63% reduction in risk.
An HR of 0.26 means that the estimated instantaneous rate of progression or death for vemurafenib was 26% of that for dacarbazine. The corresponding relative reduction in estimated hazard is 74%.
It does not mean that 74% of participants remained progression-free or that the probability of progression or death for every patient was reduced by exactly 74%.
The OS 95% CI of 0.26–0.55 and PFS 95% CI of 0.20–0.33 provide information about the statistical precision of the corresponding HR estimates. Neither interval describes the range of individual patient experiences.
The reported P-values, <0.0001 for OS and <.0001 for PFS, quantify statistical evidence under the respective testing frameworks. They do not tell us how large the treatment effect is. The HR gives the relative effect estimate; the confidence interval gives its statistical uncertainty.
19. Design Features That Affect Interpretation
Superiority framework
Both primary endpoints were analyzed under a superiority hypothesis rather than a non-inferiority framework. A non-inferiority margin therefore does not form part of the reported primary interpretation.
No factorial design
The registry identifies a parallel two-arm design. No factorial design is reported in the ClinicalTrials.gov record.
Interim monitoring
One interim analysis for overall survival was planned at 50% information, so interim monitoring is an explicit component of the trial's statistical design.
Bayesian methods
No Bayesian statistical method is identified in the ClinicalTrials.gov record. The reported framework is based on frequentist survival-analysis methods.
20. What Is Not Reported in the Supplied Registry Data
The ClinicalTrials.gov record deliberately constrain the analysis to the information reported in the registry extract. Several commonly presented clinical-trial elements are not included in that extract.
| Topic | Status in the ClinicalTrials.gov record |
|---|---|
| Baseline characteristics | Not provided. |
| Median overall survival | Not provided as a reported result. |
| Median progression-free survival | Not provided as a reported result. |
| Subgroup results | Not provided. |
| Kaplan-Meier event counts or curves | Not provided. |
| Detailed adverse-event categories | Not provided beyond serious adverse-event counts by arm. |
| Complete stratification factors | Not provided in the registry-reported analysis text. |
| Complete interim-analysis boundary | Not provided. |
| Missing-data or imputation procedures | Not provided. |
Leaving these items out is intentional. A statistical analysis page is more useful when it distinguishes an unreported quantity from an inferred one.
21. Learning Pathway: Statistical Concepts in BRIM-3
Learn more about the methods used in this trial:
22. Related Statistical Calculators
23. Primary Sources
- ClinicalTrials.gov: BRIM-3, NCT01006980.
- Linked publication record: PubMed PMID 32746839.
- Linked publication record: PubMed PMID 28961848.
- Linked publication record: PubMed PMID 25884515.
- Linked publication record: PubMed PMID 24983357.
- Linked publication record: PubMed PMID 24508103.
Continue through the Clinical Biostats statistical learning pathway
Explore the statistical concepts behind randomized time-to-event trials, then connect those concepts to calculators and clinical-trial analysis workflows.
24. Record Summary
BRIM-3 provides a clear example of a randomized phase 3 superiority trial in which both primary endpoints are time-to-event outcomes. The registry reports a 0.37 hazard ratio for overall survival with a two-sided 95% CI of 0.26–0.55 and P < 0.0001, and a 0.26 hazard ratio for progression-free survival with a two-sided 95% CI of 0.20–0.33 and P < .0001. Both analyses used the log-rank test as the reported comparison method and hazard ratio as the effect measure.
The statistical interpretation depends on more than those four numbers. The overall-survival analysis used the registry-defined ITT population, the PFS analysis used a specified ITT subset based on the October 27, 2010 randomization cutoff, and the trial included an interim overall-survival analysis at 50% information. The ClinicalTrials.gov record also identify stratified analysis as an analysis concept and unstratified Cox regression as the method used to estimate the PFS hazard ratio.
Most importantly, the hazard ratios should be read as relative time-to-event measures, not as percentages of patients benefiting. Confidence intervals describe uncertainty around the estimates, while P-values describe statistical evidence under the specified testing framework. The combination of randomized allocation, ITT analysis, log-rank testing, hazard-ratio estimation, confidence intervals, and interim monitoring makes BRIM-3 a useful case study in the statistical analysis of clinical time-to-event data.