GSK1120212 vs Chemotherapy in Advanced or Metastatic BRAF V600E/K Mutation-positive Melanoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for GSK1120212 vs Chemotherapy in Advanced or Metastatic BRAF V600E/K Mutation-positive Melanoma (NCT01245062), a randomized phase 3 study. The primary outcome is Progression-free Survival in BRAF V600E Mutation-positive Participants Without a History of Brain Metastases as Assessed by the Investigator and Independent Review.

2. Clinical Question

The population and endpoint definitions matter when interpreting the scope of the trial. Although eligibility included BRAF V600E/K mutation-positive melanoma, the named primary efficacy population was limited to BRAF V600E-positive disease without a history of brain metastases. The primary endpoint therefore does not, by itself, describe every participant eligible for the overall study. The registry also lists progression-free survival and overall survival outcomes in broader or differently defined participant groups, but does not provide a single reduced comparison for the primary outcome.

3. Trial Design

This was a Phase III randomized, open-label study with a crossover model. The registry records 322 participants enrolled. The study summary described approximate planned enrollment of 297 participants, with 2:1 randomization: 198 assigned to GSK1120212 and 99 to chemotherapy. These figures describe the stated plan, not a reported account of final randomization by arm. The registry lists no masking, consistent with the open-label design.

The intervention was single-agent GSK1120212, described as a MEK inhibitor. The comparator was chemotherapy chosen by the investigator: dacarbazine or paclitaxel. Participants with progression on chemotherapy were offered the option to receive GSK1120212. This crossover feature is important to the interpretation of outcomes that accumulate after progression, particularly overall survival: later treatment could differ from the treatment initially assigned. The registry does not report how many participants crossed over in the full study flow, although safety data separately list a crossover group.

The study began on 2010-11-22, reached primary completion on 2011-10-26, and is recorded as completed. The primary endpoint was progression-free survival in participants with BRAF V600E mutation-positive melanoma and no history of brain metastases, assessed by the investigator and independent review. The registry describes follow-up for this endpoint from Day 1 until the earliest date of disease progression or death due to any cause, with an average of 20.3 months stated in the timeframe.

Randomization helps balance participant characteristics across assigned groups on average, while open-label treatment can affect care and assessment in ways that masking is designed to limit. Independent review offers a separate assessment of progression, but the registry does not report enough information to determine the precise procedures used to resolve any differences between assessments. The allocation ratio, randomization procedure, stratification factors, and detailed protocol-level analysis plan are 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.

Before assignment: Participants (par.) were stratified for lactate dehydrogenase and prior CT for advanced or metastatic disease. 1059 par. were screened and 322 were enrolled to receive trametinib (214 par.) or CT (108 par.) until disease progression, death, or withdrawal. Par. randomized to CT were allowed to cross-over to trametinib if disease progressed.

Randomization and Crossover Phase

Reasons for not completing this period:

Cross-over Phase

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Primary Efficacy Population

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.

6. Primary Endpoint

The registry lists the primary outcome as Progression-free Survival in BRAF V600E Mutation-positive Participants Without a History of Brain Metastases as Assessed by the Investigator and Independent Review, measured over Day 1 until the earliest date of disease progression or death due to any cause (average of 20.3 months).

Progression-free survival (PFS) measures the time from randomization until the first documented disease progression or death. For the primary endpoint, the registry identifies participants with BRAF V600E mutation-positive melanoma and no history of brain metastases as the analysis population. Tumour response and progression were evaluated using Response Evaluation Criteria in Solid Tumors, Version 1.1. The registry describes progression as at least a 20% increase in the sum of target-lesion diameters, with an absolute increase of at least 5 millimeters, the appearance of at least one new lesion, or sufficiently significant worsening of non-target lesions to require discontinuation of study treatment.

PFS is used because it captures the period during which participants are alive without documented progression, combining two clinically meaningful events in a time-to-event measure. It can provide information about disease control before progression or death, rather than relying only on a status measured at one fixed time. It does not measure overall survival, quality of life, or the experience of every participant in other respects.

Both investigator assessment and blinded independent central review are named for the primary endpoint. In an open-label study, investigators know which treatment is assigned, so an independent review can offer a separate assessment of imaging and progression. The registry record does not report the primary endpoint medians, confidence intervals, or sponsor-reported hazard ratio in a single reduced comparison. The follow-up timeframe is described as Day 1 until the earliest date of progression or death, with an average of 20.3 months.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Progression-free survival is a time-to-event endpoint. Each participant contributes time beginning at randomization, and the event is the first documented progression or death. Participants who have not had a recorded event by the end of their observed follow-up may contribute information up to that point without being treated as though an event occurred. General statistical explanation: time-to-event methods are designed to use both event times and the length of follow-up, including incomplete follow-up, rather than reducing every participant to a simple event/no-event status at one date. The registry record does not report the detailed censoring rules used for this trial.

What a median represents

The primary endpoint is described using a median. In general, the median time-to-event is the time by which half of the relevant population is estimated to have experienced the event, subject to the analysis method and follow-up. It is not the average time to progression or death, nor does it describe the timing of an event for every participant. A median alone also does not show the full pattern of event times. The registry’s primary outcome title identifies a median and a 95% confidence interval, but the numerical median results are not reported in the registry record.

What a confidence interval adds

In general, a confidence interval expresses statistical uncertainty around an estimate. A narrower interval indicates greater precision under the method used; a wider interval indicates less precision. A 95% confidence interval is not a guarantee that the true value lies in that particular interval. Its interpretation depends on the study design and the method used to calculate it. Because the primary endpoint’s numerical intervals are not reported in the registry record, the precision of the primary estimate cannot be assessed from the available information.

Why the two assessments matter

The primary endpoint was assessed by the investigator and by a blinded, independent central review committee. The trial itself was open-label, so the investigator knew treatment assignment. General statistical explanation: knowledge of assignment can influence aspects of assessment or decisions around testing, even when outcomes are defined using objective criteria. A blinded independent review can provide an additional assessment that is less exposed to knowledge of treatment allocation. It is useful to know whether investigator and central-review results align, but the record does not give a single reduced comparison or enough numerical results to assess that agreement.

The endpoint definition refers to Response Evaluation Criteria in Solid Tumors, Version 1.1. The registry describes progression using changes in target-lesion measurements, new lesions, or worsening non-target lesions sufficient to require stopping study treatment. Such criteria specify how tumour changes are classified. Their application still depends on assessments over time and the handling of observations, which are not detailed in the registry record beyond the stated definition.

Hazard ratios and time-to-event comparisons

General statistical explanation: a hazard ratio compares the event rate at a given time between groups, among participants who have not yet had the event, under the model used. It is not the ratio of median times and is not a direct statement about an individual participant’s outcome. Its interpretation depends on the model and assumptions, including how the relative event rates behave over follow-up. The registry identifies sponsor-reported hazard ratios as the source used for time-to-event calculations, but no hazard-ratio values are included in the registry record. Accordingly, no estimate or interpretation of a hazard ratio can be stated.

A hazard ratio and a median answer related but different questions. The median summarizes a point on the estimated event-time distribution, while a hazard ratio summarizes a relative comparison in event rates over time as represented by the analysis model. Either can be accompanied by uncertainty estimates. Without the actual estimates, confidence intervals, and analysis details, neither the size nor precision of a group difference can be evaluated.

Allocation, crossover, and interpretation

Random assignment is intended to make treatment groups comparable at baseline on average, including for factors that are not measured. It does not guarantee that every characteristic is balanced in a particular trial. The study is described as randomized and open-label, with a planned 2:1 allocation. The randomization method and any stratification factors are not reported in the registry record.

The crossover option allowed participants with progression on chemotherapy to receive GSK1120212. General statistical explanation: crossover can complicate comparisons of outcomes after the initial treatment period because participants may subsequently receive a different treatment from the one first assigned. The extent of that issue depends on who crossed over, when they did so, and how the analysis handled subsequent treatment. Those details are not reported in the registry record. The separate safety group for crossover participants does not provide a complete account of crossover’s effect on efficacy analyses.

The sample-size assumptions recorded for planning illustrations specify a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect defined as a fraction of the observed effect. For time-to-event outcomes, the illustration uses the total number of events under the Schoenfeld approach. These are planning illustrations based on the observed effect, not the trial’s original design justification and not observed power. The values of the illustrations are not stated in the registry record for this explanation. The registry’s own sample-size justification and the assumptions used in its original design are not reported in the registry record.

General statistical explanation: over-dispersion matters when outcome variability is greater than a model assumes, because the model may then understate uncertainty and make estimates appear more precise than warranted. No over-dispersion issue or correction is reported for this trial, and the primary endpoint is time-to-event, so this general point should not be mistaken for a description of the trial’s analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary PFS outcome alongside multiple secondary outcomes. These include PFS and overall survival in all participants, outcomes in specified BRAF V600E subgroups, and response measures assessed by the investigator or independent review. When a study evaluates multiple outcomes or multiple participant subgroups, the chance of at least one apparently notable result can increase if each is interpreted without considering the full set of comparisons. General statistical explanation: multiplicity procedures can control this risk by specifying which tests are primary, how secondary tests are ordered, or how the significance threshold is adjusted. The registry record does not report a multiplicity strategy or the statistical hierarchy among outcomes.

The record identifies the primary efficacy population as participants with BRAF V600E mutation-positive melanoma without a history of brain metastases. It also lists several secondary populations and assessments. The details of how participants were assigned to analysis populations, how protocol deviations were handled, and how missing outcome data were treated are not reported in the registry record. The PFS definition identifies progression or death as events, but detailed censoring rules and procedures for incomplete assessment schedules are not reported.

The crossover option has particular relevance to later outcomes. Participants assigned to chemotherapy who progressed could be offered GSK1120212, but the registry does not report a specific method for accounting for crossover in overall-survival analyses. The record also does not report interim analyses, stopping rules, or a detailed statistical analysis plan. Their absence from the registry record should not be interpreted as proof that no such procedures existed; it means their details are not reported there.

Because the primary outcome was not reduced to a single comparison and numerical primary estimates are not reported in the registry record, an adjustment for multiplicity or the treatment of missing data cannot be evaluated from a primary result. The reported endpoint definitions alone do not establish how every analysis was conducted.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pyrexia (4.0%), cellulitis (2.9%), erysipelas (2.4%), anaemia (2.0%), pneumonitis (1.9%).

The registry reports serious adverse events by treatment group and gives the number at risk and the number affected. For Trametinib, 211 participants were at risk and 52 were affected; for chemotherapy, 99 were at risk and 19 were affected. A separate crossover-from-chemotherapy-to-Trametinib group lists 70 at risk and 18 affected. The registry also reports other adverse events, with 207 of 211 participants in the Trametinib group, 88 of 99 in the chemotherapy group, and 66 of 70 in the crossover group affected. These are group-specific counts, not estimates calculated across the trial.

The listed serious adverse-event terms and percentages are pyrexia, 4.0%; cellulitis, 2.9%; erysipelas, 2.4%; anaemia, 2.0%; pneumonitis, 1.9%; and sepsis, 1.4%. The record lists deaths of 172 in the Trametinib group, 22 in the chemotherapy group, and 53 in the crossover group. The registry entries do not specify that these deaths were caused by treatment, and the figures should not be interpreted as treatment-attributable deaths.

The groups have different denominators and include a separate crossover group. Counts alone do not adjust for differences in exposure time, participant characteristics, or follow-up. Serious adverse events and other adverse events are distinct categories. These figures describe what the registry reports; they do not by themselves establish comparative safety or causation.

12. What the Result Does, and Does Not, Mean

This trial addresses a defined comparative question: GSK1120212 versus investigator-choice chemotherapy in advanced or metastatic BRAF mutation-positive melanoma, with PFS as the primary endpoint in a narrower BRAF V600E-positive population without a history of brain metastases. It is a randomized, open-label Phase III study, and participants with progression on chemotherapy could be offered the experimental treatment. These features help explain the intended comparison and the context in which outcomes were collected.

The registry record does not report a single reduced primary endpoint comparison or the numerical PFS estimates needed to describe the observed difference and its precision. The record names medians and 95% confidence intervals as the endpoint format, but the numerical values are not reported in the registry record for this explanation. As a result, the direction and size of the primary treatment contrast cannot be stated. The same limitation applies to interpreting a hazard ratio, which is not numerically.

The record’s outcome list and safety counts are not substitutes for a complete primary efficacy result. A list of planned outcomes indicates what was assessed or registered, not what the comparison showed. Safety counts describe recorded events by group, but they do not establish cause or a fair comparative risk without fuller context. The crossover option also means that outcomes after progression may reflect more than the initial assigned treatment; the registry does not report the analytic details needed to quantify that issue.

These limits do not invalidate the trial design. They define what can be concluded from the registry record as represented. To interpret an efficacy effect, readers need the group estimates, uncertainty intervals, and relevant analysis details. To interpret safety comparisons, they need appropriate context for exposure, follow-up, and event attribution. Without those details, the sound interpretation is restricted to the study question, endpoint definitions, and the descriptive safety figures that are reported.

Nothing in the design description or the adverse-event counts alone establishes whether one treatment is preferable. The registry record supports a description of the trial and its registered outcome framework, but not a claim about the efficacy or safety of either treatment.

13. Why This Trial Matters Statistically

The trial illustrates why defining the analysis population is as important as naming the disease. Eligibility included BRAF V600E/K mutation-positive melanoma, while the primary efficacy population was specifically BRAF V600E mutation-positive disease without a history of brain metastases. Results for that primary population would answer a narrower question than results for all enrolled participants. The registry’s listed secondary populations further emphasize that estimates can depend on who is included.

It also illustrates the value of distinguishing endpoint definition from endpoint result. The registry describes PFS, its time origin, the event definition, and the assessment approaches. Those details clarify what an analysis should measure, but they do not reveal the comparative estimate. A numerical estimate and its uncertainty are needed to describe both the magnitude and precision of a treatment contrast.

The open-label design and independent central review provide another statistical lesson. Knowledge of treatment assignment is part of the trial context, while blinded independent review offers a separate route for assessing progression. Reporting results for both assessments, with their uncertainty and analysis details, would help readers evaluate whether the interpretation depends on the assessment approach. A single reduced comparison is not reported in the registry record.

Finally, the crossover option connects design to interpretation. When participants in the chemotherapy group can receive GSK1120212 after progression, later outcomes may reflect subsequent treatment as well as initial assignment. This is especially relevant when interpreting survival after progression. Understanding that issue requires the crossover pattern and analysis strategy, neither of which is fully reported in the registry record. The trial therefore highlights the need to read population, endpoint, assessment, and treatment switching together rather than treating a design label as a complete account of the evidence.

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 main limitation for interpreting efficacy from this registry record is that it does not report one reduced primary PFS comparison or the numerical estimates and confidence intervals needed to assess its magnitude and precision. The record identifies several outcome measures, categories, and time points, but does not present a single comparison in the information used. The sponsor-reported hazard ratio is not numerically stated.

The primary efficacy population is narrower than the overall eligibility population: it is defined by BRAF V600E mutation-positive melanoma and no history of brain metastases, whereas eligibility included BRAF V600E/K mutation-positive tumours. The record lists other outcome populations, but does not provide the numerical results needed to understand how estimates varied across them.

The study was open-label, with investigator assessment and blinded independent central review named for PFS. Detailed procedures for assessment, adjudication, missing scans, censoring, and analysis of incomplete follow-up are not reported in the registry record. Neither the randomization procedure nor stratification details are reported. The registry does not report the multiplicity strategy, interim analyses, stopping rules, or detailed statistical analysis plan.

Crossover from chemotherapy to GSK1120212 was offered after documented progression. The number of participants crossing over in the overall study and the method for accounting for crossover in later outcomes are not reported in the registry record. This limits interpretation of outcomes after progression, particularly overall survival.

Safety data are presented for separate treatment and crossover groups, with different numbers at risk. The counts alone do not account for treatment exposure or follow-up duration, and the registry entries do not establish event causality. The sample-size illustration assumptions are not the trial’s original design justification and should not be treated as observed power. The original sample-size justification is not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: GSK1120212 vs Chemotherapy in Advanced or Metastatic BRAF V600E/K Mutation-positive Melanoma — NCT01245062.
• Registry record last updated 2018-04-05; status last verified 2018-01.
• Results first posted 2013-03-15.
• 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.

18. Record Summary

The registry describes NCT01245062 as a completed, randomized, open-label Phase III study of GSK1120212 versus investigator-choice chemotherapy in advanced or metastatic BRAF V600E/K mutation-positive melanoma. It records 322 participants enrolled and a crossover option to GSK1120212 after progression on chemotherapy.

The primary endpoint was PFS in participants with BRAF V600E mutation-positive melanoma without a history of brain metastases, assessed by the investigator and blinded independent central review. PFS was defined from randomization to documented progression or death. The record does not report a single reduced primary comparison with numerical estimates and confidence intervals in the information available for this explanation.

Serious and other adverse-event counts are listed for Trametinib, chemotherapy, and a crossover group. Those descriptive counts do not alone establish comparative safety or causation. Detailed analysis methods, missing-data procedures, multiplicity strategy, and crossover handling are not reported in the registry record.