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 Study of Patients With Metastatic and/or Advanced Renal Cell Carcinoma, Treated With Sunitinib/Axitinib. (NCT04033991), a registered phase not stated study. The primary outcome is Progression Free Survival (PFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04033991 |
| Phase | Phase not stated |
| Condition | Carcinoma, Renal Cell |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 684 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Patients diagnosed with metastatic and/or advanced renal cell carcinoma (mRCC and/or aRCC) who received sunitinib as first-line treatment and/or axitinib as second-line treatment. The analysis population is described as eligible participants treated from 2002 until 30 June 2018. The registry enrollment is 684; the number included in each treatment-specific analysis is not reported in the registry record.
Intervention
The treatment lines of interest were first-line sunitinib and second-line axitinib. The study was a retrospective review of clinical data from a specialist United Kingdom oncology centre, rather than a prospective assignment of treatment.
Comparator
The central questions concern outcomes within each treatment line, including how PFS varies across MSKCC/IMDC risk categories. The registry record does not describe a randomized control group or a direct, like-for-like comparison between sunitinib and axitinib. These treatments were studied in different lines of therapy.
Primary question
What is the median progression-free survival (PFS) for patients treated with first-line sunitinib, and for patients treated with second-line axitinib, overall and by favourable, intermediate, or poor MSKCC/IMDC risk category? PFS was defined using progression, end of treatment, or death, with the detailed endpoint rules described in the registry record. Numerical estimates and confidence intervals are not reported in the registry record.
3. Trial Design
This is a real-world retrospective database study, not a randomized clinical trial. Its official title describes a study of patients diagnosed with metastatic and/or advanced renal cell carcinoma and treated with sunitinib and/or axitinib in a specialist United Kingdom oncology centre. The registry lists Pfizer as sponsor and the study status as completed. Registry enrollment is 684, but that figure does not establish how many participants contributed to each treatment-line or risk-category analysis.
The clinical data covered treatment from 2002 until 30 June 2018. The primary endpoint timeframe describes the period from treatment start to progression, death, or end of treatment, with participants still on treatment censored on 30 June 2018. The record also describes the data as retrieved and observed retrospectively for approximately 1.2 years. The study start is recorded as 2019-09-27 and primary completion as 2020-12-18; those registry dates do not change the earlier dates covered by the clinical database.
The primary objective was to assess PFS for first-line sunitinib and second-line axitinib, including stratification by MSKCC/IMDC risk category. The record lists overall survival, response, duration of response, and time to treatment discontinuation among secondary outcomes. It does not describe a treatment assignment procedure, a randomized allocation, or a control arm. Because the two drugs are described in different treatment lines, the study is not a like-for-like comparison of their effects.
The record does not report the number of eligible participants in each treatment cohort, the number in each risk category, or numerical results for the primary endpoint. Details of the database extraction process, eligibility decisions, and the statistical 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.
Overall Study
| Stage | Participants With mRCC and/or aRCC |
|---|---|
| STARTED | 684 |
| Participants Who Took First-line Sunitinib Therapy | 622 |
| Participants Who Took Second-line Axitinib Therapy | 121 |
| Participants Who Took First-line Sunitinib Therapy and Then Second-line Axitinib Therapy | 59 |
| Participants Who Took Drugs Other Than Sunitinib as First-line and Then Second-line Axitinib Therapy | 62 |
| COMPLETED | 684 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis population included all eligible participants with mRCC and/or aRCC, received sunitinib as first-line treatment and/or axitinib as second-line treatment from 2002 till 30 June 2018.
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: Analysis population included all eligible participants with mRCC and/or aRCC, received sunitinib as first-line treatment and/or axitinib as second-line treatment from 2002 till 30 June 2018.
| Characteristic | Unit | Participants With mRCC and/or aRCC |
|---|---|---|
| Participants analysed | 684 | |
| Age, Customized: Less than (<) 65 years | Participants | 301 |
| Age, Customized: Greater than or equal to (>=) 65 to <75 years | Participants | 247 |
| Age, Customized: >=75 to <84 years | Participants | 124 |
| Age, Customized: Greater than or equal to (>=) 85 years | Participants | 12 |
| Sex: Female, Male: Female | Participants | 234 |
| Sex: Female, Male: Male | Participants | 450 |
| Race and Ethnicity Not Collected | Participants | — |
6. Primary Endpoint
The registry lists the primary outcome as Progression Free Survival (PFS), measured over From start of treatment to PD, death or end of treatment, whichever occurred first, from inception of database (2002) until 30 June 2018, anytime in these 16 years (from the data retrieved and observed retrospectively for approximately 1.2 years).
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | Months |
| Endpoint classification | Time-to-Event Analysis |
Progression-free survival measures the time from the first date of a treatment line until a qualifying event. In this study, the event was disease progression, the end of treatment, or death. The registry defines progression using RECIST v 1.1: a specified increase in the sum of target-lesion diameters, including an absolute increase of at least 5 millimeter (mm), or the appearance of one or more new lesions. Participants still receiving treatment were censored on 30 June 2018.
The primary endpoint is reported as median PFS in months with a 95% confidence interval. In general, a median time-to-event estimate describes the time by which the estimated event-free proportion has reached its midpoint. It can summarize follow-up when some participants have not experienced the event by the end of observation, provided the analysis accounts for censoring appropriately. The specific estimation method is not reported in the registry record.
PFS is used in oncology studies because it captures time until disease progression or death, rather than relying only on whether an event occurred by a fixed visit. Here, the endpoint also includes end of treatment, and the record specifies a special rule when treatment stopped because of toxicity: the earliest date from progression or end of treatment was assigned. These endpoint rules shape what the resulting median represents. The registry record does not report numerical medians or confidence intervals.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically focused descriptive question: how long patients remained without a recorded PFS event after first-line sunitinib or second-line axitinib, with results intended to be considered by MSKCC/IMDC risk category. It does not report numerical median PFS estimates, confidence limits, hazard ratios, or risk-category results. Consequently, the direction, magnitude, and precision of the observed outcomes cannot be assessed from the registry information.
In general, a median is a summary of the distribution of event times, not a prediction that every patient will experience the event at that time. A confidence interval communicates uncertainty around an estimated quantity. A narrower interval generally indicates greater precision, while a wider interval indicates greater uncertainty. Without the reported estimates and intervals, no conclusion about the precision of PFS in either treatment line can be drawn. The sizes of the treatment-specific and risk-stratified analysis groups are also not reported in the registry record, limiting assessment of how much information supported each estimate.
The question is framed around separate treatment lines and risk strata, not a direct comparative treatment effect. Sunitinib is considered as first-line treatment and axitinib as second-line treatment. Patients reaching a later treatment line may differ from those receiving a first-line therapy, and the registry does not describe a randomized assignment that would balance such differences. Therefore, the stated objectives alone do not establish that differences between treatment-line results would be caused by the drug rather than by patient characteristics, prior treatment, or clinical decisions.
The record specifies that PFS begins at the first date of each treatment line and describes rules for progression, treatment ending, death, and censoring. These details help define the outcome, but they do not reveal how many events occurred, how censoring was handled in the estimation procedure, or whether other analytical adjustments were made. Those methods are not reported in the registry record.
The registry lists 20 outcome measures and 12 analyses. The presence of multiple outcomes and analyses raises interpretive questions about which findings were primary and whether uncertainty from multiple testing was addressed. The multiplicity strategy is not reported in the registry record. The posted adverse-event fields list zero for the displayed serious and other event counts in both treatment groups, and no top serious terms are listed. Those entries do not supply the missing PFS results, and the record does not explain the completeness or ascertainment of adverse-event reporting.
Overall, the available registry information establishes the intended endpoint, patient setting, treatment lines, and risk categories. It does not provide the outcome estimates needed to judge the observed PFS experience or its statistical precision. Absence of numerical results in the registry record is not evidence that outcomes were favourable, unfavourable, or equivalent across groups.
9. Statistical Methods Explained
The registry describes a retrospective time-to-event analysis with median PFS and a 95% confidence interval as the primary outcome summary. It also notes that sponsor-reported hazard ratios are used for time-to-event interpretation, but no numerical hazard ratios are reported in the registry record. The specific statistical procedures used to estimate medians, confidence intervals, or hazard ratios are not reported.
What does a time-to-event endpoint represent?
In general, a time-to-event analysis uses both the time until an event and whether that event was observed during follow-up. This differs from treating every participant as if follow-up ended at the same point. Some participants may still be receiving treatment when observation closes; the record says those participants were censored on 30 June 2018. Censoring means the event time is not observed within the available follow-up, not that the event can be assumed never to occur. Valid interpretation depends on the analysis method and assumptions about censoring. The method and assumption checks are not reported in the registry record.
The event definition is study-specific. PFS starts on the first date of each treatment line and ends at progression, end of treatment, or death. The registry defines progression according to RECIST v 1.1 and specifies that a new lesion can also count as progression. If a participant stopped treatment because of toxicity, the earliest date from progression or end of treatment was assigned. As a result, this endpoint is not simply time to radiographic progression: treatment ending and death also contribute under the stated rules.
How should a median and confidence interval be read?
In general, the median is a central point in the estimated event-time distribution. It is not the mean, and it does not convey the full shape of that distribution. A 95% confidence interval describes uncertainty in the estimated median under the analysis procedure; it is not a range containing 95% of individual participant times. Confidence intervals also do not address bias from selection, measurement, or unmeasured differences between treatment groups. The registry lists the confidence interval type but does not report the estimates or the method used to calculate it.
In general, a hazard ratio compares event rates over follow-up between groups under a time-to-event model. Its interpretation depends on how groups and events are defined and on the model assumptions. A hazard ratio is not the same quantity as a difference between median PFS times. The registry record says that only the sponsor’s reported hazard ratios are used for time-to-event interpretation; the actual values, associated intervals, and model details are not reported in the registry record.
What does risk stratification add?
The primary questions specify separate PFS assessment by favourable, intermediate, and poor MSKCC/IMDC risk category. Stratification can describe whether outcomes vary across clinically defined risk groups. It does not, by itself, make treatment groups comparable or remove confounding. The record does not report category-specific participant counts, how risk categories were assigned when information was incomplete, or whether the stratification was incorporated into a statistical model.
General statistical interpretation also depends on the number of observed events and the duration and distribution of follow-up. Those details help determine how much information supports a time-to-event estimate. Event counts and treatment-specific follow-up summaries are not reported in the registry record. The listed enrollment of 684 should not be taken as the denominator for every endpoint or subgroup because the eligible analysis counts are not given.
What do the planning illustrations mean?
The registry’s planning assumptions describe illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event outcomes, the stated planning quantity is the total number of events using the Schoenfeld approach. Such calculations are planning illustrations, not observed power and not evidence that the study was designed prospectively around those assumptions. The registry does not report a protocol-based sample-size justification, and no planning quantities are stated in this record.
The registry does not report whether analyses were adjusted for potential confounders, how missing covariate or outcome information was handled, whether proportional-hazards assumptions were checked, or whether sensitivity analyses were conducted. These are important method details for a retrospective database analysis, but their absence from the registry record does not establish which procedures were or were not used outside the record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 20 outcome measures and 12 analyses. The primary objectives concern PFS for two treatment lines and risk-category strata, while secondary outcomes include overall survival, response, duration of response, and time to treatment discontinuation. Evaluating multiple outcomes or subgroups can increase the chance of finding an apparently notable result by chance if each is tested separately. In general, multiplicity procedures can control or describe this issue, but the registry record does not report whether any adjustment or prespecified hierarchy was used. It also does not report which of the listed analyses were prespecified.
The primary endpoint population is described as eligible participants with mRCC and/or aRCC who received first-line sunitinib and/or second-line axitinib from 2002 until 30 June 2018. Registry enrollment is 684, but the number eligible for each treatment-line analysis and the number included in each risk stratum are not reported in the registry record. The exact analysis denominators therefore cannot be inferred from enrollment.
The endpoint definition gives a censoring date for participants still on treatment and special rules for treatment stopped due to toxicity. These details address some aspects of incomplete event follow-up. However, missing baseline variables, incomplete outcome records, exclusions after database review, and any imputation or other missing-data methods are not reported in the registry record. The statistical plan for handling loss to follow-up or other forms of missingness is also not reported. No interim-analysis plan is described in the registry record.
11. What the Result Does, and Does Not, Mean
The record establishes that investigators intended to describe PFS among patients treated with first-line sunitinib and second-line axitinib in a real-world specialist-centre setting, including results by MSKCC/IMDC risk category. It also provides the operational definition of PFS and lists additional outcomes. These details clarify the questions asked, but the registry record does not provide numerical PFS estimates, confidence intervals, or hazard ratios. The observed outcomes and their precision therefore cannot be determined from the registry information.
Even if treatment-line estimates were available, they would describe outcomes in the studied patient groups and care setting. A retrospective database study does not, on the information in this record, establish that one treatment caused better or worse outcomes than another. The treatments are attached to different lines of therapy, and the record does not describe randomized allocation or a like-for-like control comparison. Differences across risk categories would likewise be descriptive unless the analysis and assumptions supported a causal interpretation.
A median PFS would not mean that each participant experienced an event at that time, and a confidence interval would express uncertainty about the estimate rather than the range of individual outcomes. A hazard ratio, if reported, would summarize a relative time-to-event contrast under its model; it would not be interchangeable with a difference in medians. These are general statistical interpretations, not claims about unreported results from this study.
The registry’s adverse-event fields list zero counts in the displayed categories for both treatment groups, with no top serious terms listed. The record does not explain event ascertainment or reporting completeness, so those entries alone cannot characterize the full safety experience. The absence of numerical efficacy results in the registry record should not be interpreted as evidence for or against either treatment.
12. Why This Trial Matters Statistically
This study raises useful statistical questions about how treatment outcomes are described in routine oncology care. The stated objective is not limited to an overall PFS summary: it also asks how PFS varies by MSKCC/IMDC risk category. Such subgroup descriptions can help readers understand whether an overall estimate conceals variation across patient-risk groups. Their usefulness depends on adequate information within each group and transparent reporting of estimates and uncertainty; category counts and results are not reported in the registry record.
The record also illustrates why endpoint definitions matter. PFS is defined from the start of each treatment line and includes progression, end of treatment, or death, with additional rules for censoring and stopping treatment due to toxicity. A reader needs those rules to know what an event-time summary represents. In a retrospective setting, clear definitions are especially important because outcomes are abstracted from existing data rather than collected under a newly assigned treatment protocol.
Another statistical point is the distinction between describing outcomes and comparing treatments. Sunitinib is assessed in the first-line setting and axitinib in the second-line setting. Those are different clinical contexts, and the registry does not describe randomization or a direct control comparison. A statistical contrast between their results would not automatically identify a treatment effect.
Finally, this record shows the importance of complete reporting. It identifies the study population, endpoint, and planned questions, but does not report numerical primary results, subgroup counts, or key analysis details. Without those elements, readers cannot assess the magnitude or precision of the findings. Clear reporting of estimates, uncertainty, analysis populations, and missing-data handling is necessary for meaningful statistical interpretation.
13. 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 principal limitation for interpreting the registry record is that it does not report numerical PFS results. Median estimates, confidence intervals, risk-stratum results, and hazard ratios are absent, so the outcome magnitude and precision cannot be evaluated. The record also does not report the number of participants included in each treatment-line or subgroup analysis. Enrollment of 684 is not enough to establish those analysis denominators.
The retrospective database design means that the study describes patients treated in routine care rather than participants assigned prospectively to treatment by a randomized procedure. The registry does not report a treatment allocation process or a like-for-like control group. Sunitinib and axitinib are examined in different treatment lines, so direct comparison would be vulnerable to differences between the patient groups and clinical contexts.
The record describes the endpoint and some censoring rules, but does not report the statistical estimator, confidence-interval method, hazard-ratio model, covariate adjustment, or checks of model assumptions. It also does not report how missing data, incomplete records, or loss to follow-up were handled. The process for selecting eligible records and the completeness of outcome ascertainment are not described.
Multiplicity is relevant because the record lists multiple outcomes and analyses, but any adjustment or prioritization strategy is not reported. The registry also does not give category-specific counts or explain the handling of missing risk information. These gaps restrict assessment of precision and robustness. They do not establish that any particular method was absent from analyses conducted outside the registry record.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Study of Patients With Metastatic and/or Advanced Renal Cell Carcinoma, Treated With Sunitinib/Axitinib. — NCT04033991.
- Registry record last updated 2023-04-06; status last verified 2023-01.
- Results first posted 2022-02-18.
- 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.
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17. Record Summary
NCT04033991 is a completed retrospective database study sponsored by Pfizer. Its official title describes patients with metastatic and/or advanced renal cell carcinoma treated at a specialist United Kingdom oncology centre with sunitinib and/or axitinib. Registry enrollment is 684. The study start is 2019-09-27 and primary completion is 2020-12-18.
The primary endpoint is median PFS in months with a 95% confidence interval. The objectives concern first-line sunitinib and second-line axitinib, including MSKCC/IMDC risk categories. The clinical data period is described as 2002 until 30 June 2018. The registry record lists secondary outcomes including overall survival, response, duration of response, and time to treatment discontinuation.
Numerical primary results, subgroup analysis counts, and key statistical analysis details are not reported in the registry record. The study is not described as randomized or as a like-for-like treatment comparison.