← Clinical Trials
Colorectal Cancer (CRC) Phase 3 Time-to-Event Analysis NCT05198934

Sotorasib and Panitumumab Versus Investigator's Choice for Participants With Kirsten Rat Sarcoma (KRAS) p.G12C Mutation: Complete Statistical Analysis

This analysis examines the registry’s reported progression-free survival results for sotorasib plus panitumumab at two dose levels compared with investigator’s choice in previously treated metastatic colorectal cancer with a KRAS p.G12C mutation. It also explains the endpoint, the limits of the posted comparisons, and how to interpret the serious adverse event counts.

Trial start: 2022-04-19  ·  Enrollment: 160  ·  Sponsor: Amgen
Scope of this record

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 Sotorasib and Panitumumab Versus Investigator's Choice for Participants With Kirsten Rat Sarcoma (KRAS) p.G12C Mutation (NCT05198934), a randomized phase 3 study. The primary outcome is Progression-free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 as Assessed by BICR.

160
Enrollment
Phase 3
3
Arms
In the primary outcome
n/a
Effect
No re-analysis shown
n/a
95% CI
See limitations
FeatureRegistry value
ClinicalTrials.gov identifierNCT05198934
PhasePhase 3
ConditionColorectal Cancer (CRC)
AllocationRandomized
Design modelParallel
MaskingNone (open label)
Enrollment160
Arms in the primary outcome3
Lead sponsorAmgen
Results postedYes

2. Clinical Question

Population

The study concerns previously treated participants with metastatic colorectal cancer and a KRAS p.G12C mutation. The primary analysis population is the FAS, defined in the registry record as all randomized participants. The record lists 160 participants enrolled. It does not report further eligibility details or participant characteristics in the primary outcome description.

Intervention

Participants were assigned to one of two sotorasib and panitumumab combinations: sotorasib 240 mg once daily with panitumumab, or sotorasib 960 mg once daily with panitumumab. The registry’s brief summary identifies progression-free survival as the main comparison of interest for both dose combinations.

Comparator

The active comparator was investigator’s choice of trifluridine and tipiracil or regorafenib. The record does not report how the choice between those medicines was made, or how many participants in the comparator group received each option.

Primary question

The primary question is how progression-free survival, assessed by BICR under RECIST version 1.1, was distributed in each treatment group. The posted medians are 2.04 months for investigator’s choice, 3.91 months for sotorasib 240 mg plus panitumumab, and 5.62 months for sotorasib 960 mg plus panitumumab. These descriptive values do not by themselves establish the size or statistical significance of a treatment effect. The registry record does not report hazard ratios or tests for these comparisons.

3. Trial Design

This was a phase 3, multicenter, randomized, open-label, active-controlled study with a parallel-group design. The registry record lists the study as completed, with enrollment of 160. The study start date is 2022-04-19, and the primary completion date is 2025-07-16. These dates describe the registry record; they do not, on their own, establish the duration of follow-up for each participant.

The study included three groups. One received sotorasib 960 mg once daily with panitumumab; another received sotorasib 240 mg once daily with panitumumab. The investigator’s-choice group received trifluridine and tipiracil or regorafenib. The registry does not report the randomization ratio, the method used to generate the allocation sequence, or the process for selecting between the comparator medicines.

The primary outcome was progression-free survival assessed by BICR using RECIST version 1.1. The registry defines this outcome as the time from randomization until disease progression or death from any cause, whichever occurred first. Its primary analysis population was the FAS, described as all randomized participants. The reported group sizes for this outcome were 54 for investigator’s choice, 53 for sotorasib 240 mg plus panitumumab, and 53 for sotorasib 960 mg plus panitumumab.

The study was open-label, so treatment assignment was not masked to participants or investigators according to the record. The record does not describe masking arrangements for BICR, details of the central review process, or the statistical analysis plan. It lists secondary outcomes including overall survival, response outcomes, investigator-assessed progression-free survival, and treatment-emergent adverse events. Those secondary outcomes should be distinguished from the primary BICR-assessed endpoint.

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 with previously treated metastatic colorectal cancer (CRC) with the kirsten rat sarcoma (KRAS) p.G12C mutation were enrolled and randomized 1:1:1 to receive either sotorasib 240 mg daily (QD) and panitumumab, sotorasib 960 mg QD and panitumumab, or investigator's choice (trifluridine and tipiracil, or regorafenib). Investigator's choice was declared prior to randomization.

Overall Study

StageTrifluridine and Tipiracil or RegorafenibSotorasib 240 mg + PanitumumabSotorasib 960 mg + Panitumumab
STARTED545353
COMPLETED000
NOT COMPLETED545353

Reasons for not completing this period:

ReasonTrifluridine and Tipiracil or RegorafenibSotorasib 240 mg + PanitumumabSotorasib 960 mg + Panitumumab
Participants continuing trial293233
Withdrawal of consent from trial522
Death191818
Lost to Follow-up110

Analysis population for the primary outcome, as defined in the registry: FAS included all randomized participants.

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.

Population: Full analysis set (FAS) included all randomized participants.

CharacteristicUnitTrifluridine and Tipiracil or RegorafenibSotorasib 240 mg + PanitumumabSotorasib 960 mg + PanitumumabTotal
Participants analysed545353160
Age, Continuousyears61.5 (SD 11.7)58.2 (SD 11.9)60.9 (SD 11.6)60.2 (SD 11.7)
Sex: Female, Male: FemaleParticipants30272481
Sex: Female, Male: MaleParticipants24262979
Ethnicity (NIH/OMB): Hispanic or LatinoParticipants80412
Ethnicity (NIH/OMB): Not Hispanic or LatinoParticipants455347145
Ethnicity (NIH/OMB): Unknown or Not ReportedParticipants1023
Race/Ethnicity, Customized: AsianParticipants1222640
Race/Ethnicity, Customized: Black or African AmericanParticipants0101
Race/Ethnicity, Customized: WhiteParticipants373042109
Race/Ethnicity, Customized: Other/UnknownParticipants50510

6. Primary Endpoint

The registry lists the primary outcome as Progression-free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 as Assessed by BICR, measured over From randomization until DCO or death; median (min, max) time on trial was 6.23 (0.1, 14.0) months.

ElementRegistry entry
Result typeMedian
Measure of spread95% Confidence Interval
Unitmonths
Endpoint classificationTime-to-Event Analysis

Progression-free survival measures the time from randomization until the first of disease progression or death from any cause. In this trial, progression was assessed using RECIST version 1.1 by BICR. The registry describes the primary analysis population as the FAS, including all randomized participants. The recorded timeframe is from randomization until DCO or death.

This endpoint is used to describe how long participants remain alive without recorded disease progression. It differs from overall survival, which concerns time to death, and from response outcomes, which assess tumor response rather than time to progression or death. The registry lists overall survival and several response measures as secondary outcomes.

The reported median is a summary of the time-to-event distribution: in general, a median marks the point at which half of the estimated distribution has experienced the event. The registry reports a median PFS of 2.04 months for investigator’s choice, with a 95% confidence interval of 1.91 to 3.91 months; 3.91 months for sotorasib 240 mg plus panitumumab, with a 95% confidence interval of 3.61 to 5.75 months; and 5.62 months for sotorasib 960 mg plus panitumumab, with a 95% confidence interval of 4.21 to 6.31 months.

The record also reports median time on trial of 6.23 months, with a minimum and maximum of 0.1 and 14.0 months. This is not the same measure as median progression-free survival. The registry does not report the event counts or the censoring details needed to further characterize the endpoint results.

7. Why No Re-analysis Is Shown

Reported as posted, not recalculated. Values missing or not estimable for a two-arm comparison (median time endpoint). A result is recalculated only when the posted data support a clean two-arm comparison, so no result is shown beyond what the sponsor posted.

8. Statistical Interpretation

Clinical Biostats interpretation

The registry reports median progression-free survival of 2.04 months in the investigator’s-choice group, 3.91 months in the sotorasib 240 mg plus panitumumab group, and 5.62 months in the sotorasib 960 mg plus panitumumab group. Each estimate is accompanied by a 95% confidence interval: 1.91 to 3.91 months, 3.61 to 5.75 months, and 4.21 to 6.31 months, respectively. These are the posted descriptive results for the primary endpoint.

The medians are different across the three groups, but they are not a complete comparison of the time-to-event distributions. A median does not convey how events were distributed before or after that point, and it does not describe the pattern of censoring. The confidence intervals indicate uncertainty around the median estimates. They should not be read as a substitute for a direct comparison between groups or as a test of statistical significance.

The registry record does not report a hazard ratio, its confidence interval, or a p-value for either sotorasib combination versus investigator’s choice. It therefore does not support a numerical statement about the relative event rate over follow-up or a conclusion about statistical significance. The posted group medians alone cannot establish that any observed difference is caused by treatment assignment. No sponsor-reported hazard-ratio analysis is available in the record.

The study was randomized, which is relevant to interpreting comparisons between assigned groups, but the registry summary does not provide enough analysis detail to evaluate the comparison fully. In particular, the record does not report the prespecified statistical model, stratification factors, censoring rules, or any sensitivity analyses. It also does not give the number of progression or death events contributing to each analysis.

The median time on trial was 6.23 months, with a minimum and maximum of 0.1 and 14.0 months. This describes observed time on trial in the registry summary; it should not be treated as the length of follow-up for every participant. The available results should consequently be read as group-level endpoint summaries with uncertainty, rather than as a full account of the comparative treatment effect or of each participant’s experience.

9. Statistical Methods Explained

The primary endpoint is a time-to-event outcome. Its event is the first recorded occurrence of disease progression or death from any cause, and the time origin is randomization. The registry specifies RECIST version 1.1 and BICR assessment for progression. The outcome is reported as a median in months with a 95% confidence interval. The record does not give the estimator or statistical model used to produce those values, so it is not possible to describe the actual estimation procedure more specifically.

What does a median PFS describe?

As a general statistical explanation, a median time-to-event estimate summarizes the point in the estimated event-time distribution at which half of the distribution has reached the event. It is not an average, and it does not show the full shape of the distribution. Two groups can have different medians while still having other features of their event-time patterns that the median alone does not reveal.

The registry’s reported medians are 2.04 months for investigator’s choice, 3.91 months for sotorasib 240 mg plus panitumumab, and 5.62 months for sotorasib 960 mg plus panitumumab. These values describe the groups; they do not, by themselves, estimate a treatment effect with a stated level of statistical evidence. The record does not report the hazard ratios that would ordinarily provide a relative time-to-event comparison in the sponsor’s analysis.

What does a 95% confidence interval add?

As a general explanation, a confidence interval expresses uncertainty in an estimated quantity under the assumptions of the method used. A wider interval indicates less precision than a narrower interval on the same scale. The posted intervals are 1.91 to 3.91 months for investigator’s choice, 3.61 to 5.75 months for sotorasib 240 mg plus panitumumab, and 4.21 to 6.31 months for sotorasib 960 mg plus panitumumab. The record does not report the interval-construction method. These intervals are for group medians, not for a direct difference or ratio between groups.

It is important not to infer a significance test merely by comparing confidence intervals. A formal comparison requires its own estimate and uncertainty, with the planned analysis method taken into account. Since no hazard ratio, comparison confidence interval, or p-value is reported for the primary endpoint, the registry record does not provide those results.

Why do time-to-event analyses need special care?

As a general explanation, time-to-event data can include participants whose event has not been observed by the end of their available follow-up. Such observations are commonly treated as censored under a specified analysis method; the timing and reasons for censoring can affect interpretation. The registry gives the endpoint timeframe as from randomization until DCO or death, but does not report detailed censoring rules or the numbers of events and censored observations. The median time on trial was 6.23 months, with a minimum and maximum of 0.1 and 14.0 months. That summary is not a substitute for participant-level follow-up information or the endpoint analysis details.

What do the planning illustrations represent?

The planning illustrations are not observed power and are not the trial’s reported sample-size justification. They use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a stated fraction of the observed effect. For time-to-event outcomes, the planning quantity is a total number of events; for other outcomes, it is participants per arm. These are general planning assumptions, not evidence about the trial’s design decisions or the certainty of its results. The registry record does not report the trial’s sample-size justification.

Over-dispersion is a general concern when outcome variation is greater than a model assumes; if present and unaccounted for, uncertainty estimates can be too small. The registry record does not identify an over-dispersion model for this endpoint, and the reported median summaries do not allow one to assess whether such a model was relevant. No inference about the actual analysis method should be drawn from general statistical considerations alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies progression-free survival as the primary outcome and lists 22 secondary outcomes. Those secondary outcomes include overall survival, response and duration measures, disease control, investigator-assessed PFS and ORR, and treatment-emergent adverse events. Considering several outcomes can raise a multiplicity issue: as a general statistical matter, testing multiple hypotheses can increase the chance of a false-positive result if the analysis does not account for the number and relationship of the tests.

The registry record does not report a multiplicity adjustment, a testing hierarchy, or which secondary outcomes were designated as confirmatory versus exploratory. It also does not report p-values or hazard ratios for the primary comparison. Consequently, no conclusion about multiplicity control or confirmatory evidence can be made from the registry summary. The presence of listed secondary outcomes does not establish that they were all formally tested.

The primary population is described as the FAS, including all randomized participants. The record does not give further details on analysis populations for secondary outcomes, protocol deviations, or exclusions from particular analyses. It does not report missing-data procedures, the handling of incomplete assessments, or the rules used for censoring PFS observations. These details matter because missing assessments and follow-up can influence time-to-event estimates and the interpretation of treatment comparisons.

For these reasons, the registry record supports a description of the posted median PFS estimates and confidence intervals, but not a full audit of the planned analysis, multiplicity strategy, missing-data handling, or secondary-outcome inference.

11. Safety Results

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

ArmParticipants with serious adverse eventsParticipants at riskPercentage
Trifluridine and Tipiracil or Regorafenib155129.4%
Sotorasib 240 mg + Panitumumab175332.1%
Sotorasib 960 mg + Panitumumab145326.4%
Participants with at least one serious adverse event
Serious adverse events by armTrifluridine and Tipiracil or…29.4%Sotorasib 240 mg + Panitumumab32.1%Sotorasib 960 mg + Panitumumab26.4%% of participants with at least one serious adverse event

Deaths

ArmDeaths (participants affected of at risk)
Trifluridine and Tipiracil or Regorafenib20 of 54
Sotorasib 240 mg + Panitumumab18 of 53
Sotorasib 960 mg + Panitumumab18 of 53

Other (non-serious) adverse events

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

ArmParticipants affected of at risk
Trifluridine and Tipiracil or Regorafenib48 of 51
Sotorasib 240 mg + Panitumumab52 of 53
Sotorasib 960 mg + Panitumumab52 of 53

Most frequent serious adverse event terms

Event termOrgan systemTrifluridine and Tipiracil or RegorafenibSotorasib 240 mg + PanitumumabSotorasib 960 mg + Panitumumab
Intestinal obstructionGastrointestinal disorders0 of 513 of 532 of 53
Small intestinal obstructionGastrointestinal disorders0 of 513 of 530 of 53
SepsisInfections and infestations0 of 510 of 533 of 53
Pulmonary embolismRespiratory, thoracic and mediastinal disorders2 of 511 of 530 of 53
NauseaGastrointestinal disorders1 of 511 of 530 of 53
VomitingGastrointestinal disorders0 of 512 of 530 of 53
PainGeneral disorders0 of 511 of 531 of 53
PyrexiaGeneral disorders0 of 512 of 530 of 53
Urinary tract infectionInfections and infestations0 of 512 of 530 of 53
Back painMusculoskeletal and connective tissue disorders0 of 511 of 531 of 53

Most frequent non-serious adverse event terms

Event termOrgan systemTrifluridine and Tipiracil or RegorafenibSotorasib 240 mg + PanitumumabSotorasib 960 mg + Panitumumab
NauseaGastrointestinal disorders18 of 5116 of 538 of 53
DiarrhoeaGastrointestinal disorders12 of 5114 of 5314 of 53
HypomagnesaemiaMetabolism and nutrition disorders1 of 5118 of 5318 of 53
Dermatitis acneiformSkin and subcutaneous tissue disorders1 of 5122 of 5313 of 53
RashSkin and subcutaneous tissue disorders1 of 5112 of 5316 of 53
Dry skinSkin and subcutaneous tissue disorders1 of 5114 of 5313 of 53
AstheniaGeneral disorders10 of 519 of 538 of 53
AnaemiaBlood and lymphatic system disorders11 of 518 of 537 of 53
VomitingGastrointestinal disorders6 of 5111 of 536 of 53
PruritusSkin and subcutaneous tissue disorders2 of 519 of 5310 of 53

Serious events with the highest arm-level rate: intestinal obstruction (5.7%), small intestinal obstruction (5.7%), sepsis (5.7%), dyspnoea (3.9%), pulmonary embolism (3.9%).

Do not overextend the safety comparison. Serious-adverse-event counts are safety observations, not efficacy outcomes, and should not be combined with the primary result into a single benefit-risk number.

The registry reports serious adverse event counts alongside the number at risk for each group. In the investigator’s-choice group, 15 participants with 51 at risk were reported with serious adverse events. In the sotorasib 240 mg plus panitumumab group, the figures were 17 with 53 at risk. In the sotorasib 960 mg plus panitumumab group, they were 14 with 53 at risk. These are posted counts and denominators; they are not, by themselves, a comparative safety analysis.

The registry also reports other adverse event counts: 48 with 51 at risk for investigator’s choice, 52 with 53 at risk for sotorasib 240 mg plus panitumumab, and 52 with 53 at risk for sotorasib 960 mg plus panitumumab. Death counts are reported as 20, 18, and 18, respectively. The record does not establish from these figures alone whether deaths were caused by treatment, disease, or another cause, and they should not be interpreted as a treatment-related death comparison.

The listed serious adverse event terms and percentages are intestinal obstruction (5.7%), small intestinal obstruction (5.7%), sepsis (5.7%), dyspnoea (3.9%), pulmonary embolism (3.9%), and vomiting (3.8%). The record does not specify the treatment group for each listed term in the summary. Counts and percentages can be affected by exposure time, event definitions, and reporting practices; those details are not reported in the registry record. No causal conclusion should be drawn from the listed figures alone.

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

The posted primary outcome results describe median PFS in three randomized groups: 2.04 months for trifluridine and tipiracil or regorafenib, 3.91 months for sotorasib 240 mg plus panitumumab, and 5.62 months for sotorasib 960 mg plus panitumumab. The respective 95% confidence intervals are 1.91 to 3.91 months, 3.61 to 5.75 months, and 4.21 to 6.31 months. These estimates provide a descriptive account of the primary endpoint in the registry record.

They do not establish the statistical significance of a comparison, quantify a relative treatment effect, or show how the full PFS distributions compare. The registry does not report hazard ratios, comparison p-values, event counts, or analysis details needed for those interpretations. It is therefore not appropriate to turn the medians into a claim that one regimen works or does not work, or to assign a cause to differences between the observed group summaries.

The trial’s randomized design is relevant to the intended comparison, but interpreting the results also depends on details such as the prespecified analysis, censoring, follow-up, and missing-data rules. Those are not reported in the registry record. The record identifies all randomized participants as the FAS for the primary endpoint, but does not provide additional participant-level or subgroup results.

The safety counts are also descriptive. Serious adverse event counts and other adverse event counts are reported with their group-specific numbers at risk, while death counts are listed separately. The registry summary does not provide enough information to attribute events to a study medicine or to compare safety formally. Overall, the results support careful description of the posted endpoint estimates and adverse event figures, while leaving important elements of comparative inference unreported.

13. Why This Trial Matters Statistically

This trial is statistically notable for comparing two dose levels of a targeted combination against an active investigator’s-choice comparator in a defined population: previously treated metastatic colorectal cancer with a KRAS p.G12C mutation. Its randomized, parallel-group design frames the intended group comparisons, while its open-label status and BICR assessment are important features to keep in view when considering how outcomes were assessed.

The primary endpoint is time to progression or death, rather than a simple event count at a single visit. This makes follow-up and censoring details central to interpretation. The registry reports medians and confidence intervals, which are useful summaries, but it does not report hazard ratios or formal comparison tests. The case illustrates why group-level median estimates should not be mistaken for a complete comparative analysis.

There are also multiple listed secondary outcomes, including overall survival, response measures, and investigator-assessed outcomes. Without a reported testing hierarchy or multiplicity procedure, their role in confirmatory inference is unclear. The registry record therefore demonstrates a practical distinction between outcomes being listed and statistical conclusions being documented.

For clinical researchers and biostatisticians, the key lesson is to separate the endpoint summaries that are available from the comparative quantities and analysis details that are not. The numerical results can be described accurately, but conclusions about statistical evidence, precision of a treatment contrast, and robustness to analysis choices require information not reported in the registry record.

14. Limitations

The registry record gives the primary outcome medians and 95% confidence intervals but does not report hazard ratios, comparison p-values, or event counts. Without these, the relative time-to-event effect and its statistical uncertainty cannot be characterized from the posted primary results. The record also does not describe the estimation method used for the medians or confidence intervals.

Important operational details are not reported in the registry record, including censoring rules, missing-assessment handling, the statistical analysis plan, and any sensitivity analyses. The primary population is identified as the FAS, but the record does not provide further details about exclusions or analysis populations for other outcomes. The median time on trial of 6.23 months, with a minimum and maximum of 0.1 and 14.0 months, does not describe each participant’s follow-up or resolve these gaps.

The study was open-label, but the record does not explain masking procedures for BICR or the conduct of central review. It also does not report how the investigator selected trifluridine and tipiracil versus regorafenib, or how many participants received each comparator option. The registry lists secondary outcomes but does not report multiplicity control or a hierarchy for interpreting them.

The serious adverse event and other adverse event figures are counts with numbers at risk. The record does not provide enough detail to interpret exposure-adjusted event rates, establish causality, or compare safety formally. These limits restrict interpretation to the descriptive results reported, rather than a complete assessment of comparative efficacy or safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

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

The registry record describes a completed phase 3, multicenter, randomized, open-label, active-controlled, parallel-group study in previously treated participants with metastatic colorectal cancer and a KRAS p.G12C mutation. Enrollment is listed as 160. The study compared sotorasib 240 mg once daily plus panitumumab and sotorasib 960 mg once daily plus panitumumab with investigator’s choice of trifluridine and tipiracil or regorafenib.

The primary outcome was BICR-assessed PFS under RECIST version 1.1, defined from randomization to progression or death from any cause, whichever occurred first. Reported medians were 2.04 months for investigator’s choice, 3.91 months for the 240 mg combination, and 5.62 months for the 960 mg combination, each with a 95% confidence interval in the registry record.

The record does not report hazard ratios, primary comparison p-values, event counts, or several analysis details needed for fuller comparative interpretation. Serious adverse event counts and other safety figures are also posted, but they do not establish causality or a formal between-group safety effect.

Clinical Biostats