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 Real-world Therapy of ALK-positive NSCLC in Sweden: the Sequencing of ALK Tyrosine Kinase Inhibitor Drugs and Their Therapeutic Outcomes Based on Data From National Registers. (NCT04647110), a registered phase not stated study. The primary outcome is Overall Survival (OS): Based on Treatment Cohort Groups.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04647110 |
| Phase | Phase not stated |
| Condition | ALK-positive NSCLC |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 549 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with ALK-positive non-small cell lung cancer whose data were retrieved from Swedish administrative registers and assessed. The registry lists an enrollment of 549, but does not report how many participants were evaluable for the primary survival outcome overall or within each treatment cohort. The outcome description says the analysis population included eligible participants and that the evaluable count depended on treatment generation.
Intervention
The study examines real-world use and sequencing of ALK tyrosine kinase inhibitors: crizotinib, alectinib, brigatinib, ceritinib, and lorlatinib. It describes treatment pathways rather than assigning a treatment. Some cohort definitions also include chemotherapy.
Comparator
The registry describes treatment cohort groups built from different sequences of therapies. It does not specify a randomized control group or a single like-for-like comparator. Allocation is not stated, and the groups should be understood as observed treatment histories rather than assigned study arms.
Primary question
The primary outcome is median overall survival, measured from the date of the first ALK TKI prescription to death from any cause or censoring. The study’s stated aim is to explore how ALK TKIs were sequenced in Swedish clinical practice and the outcomes associated with those sequences. The registry record does not report the median survival estimates or their confidence intervals, so the size and precision of any differences between cohorts cannot be assessed from the posted results.
3. Trial Design
This is a completed retrospective observational study using Swedish register data. Its official title describes a study of treatment sequencing, treatment duration, and overall survival among people with non-small cell lung cancer treated with ALK tyrosine kinase inhibitors. The registry lists Pfizer as the sponsor, an enrollment of 549, a start date of 2020-12-14, and a primary completion date of 2021-03-15. These dates describe the registered study; the survival outcome timeframe separately refers to data collected during an identification period of 9 years and says that retrieved data were assessed for approximately 3 months.
No treatment assignment is described. Instead, the analysis groups people according to the treatment sequences recorded in practice. The primary outcome description defines cohorts labeled A1, A2, B1, B2, C1, C2, and D1. The definitions combine chemotherapy, crizotinib, other second-generation ALK TKIs, and lorlatinib in different sequences. In those definitions, “any second generation ALK TKI” includes the class as described by the registry; the record does not provide participant counts for each sequence or additional rules for assigning participants to groups.
The listed interventions are crizotinib, alectinib, brigatinib, ceritinib, and lorlatinib. Secondary outcomes concern duration of treatment by treatment cohort, chemotherapy status, and the number of ALK TKI treatment lines. The registry lists 27 outcome measures but no analysis entries. It does not report a protocol-level statistical analysis plan, eligibility criteria in detail, or an explanation of how incomplete treatment histories were handled. Because treatment pathways were observed rather than assigned, cohort comparisons are descriptive and may reflect differences between people as well as differences in treatment history.
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: According to application sent to ethical counsel for this study, it was pre-planned not to report data for those cohorts/groups which had less than (\<) 5 participants at the index date. Hence, due to ethical compliance study team ensured results would only be displayed on an aggregate level for reporting arms having greater than or equal to (\>=) 5 participants at index date.
Overall Study
| Stage | Participants With No First Line Chemotherapy | Participants With First Line Chemotherapy |
|---|---|---|
| STARTED | 345 | 204 |
| COMPLETED | 345 | 204 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis population included all eligible participants whose data were retrieved from Swedish administrative registers and assessed. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure based on generation of ALK treatment.
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 whose data were retrieved from Swedish administrative registers and assessed.
| Characteristic | Unit | Participants With No First Line Chemotherapy | Participants With First Line Chemotherapy | Total |
|---|---|---|---|---|
| Participants analysed | 345 | 204 | 549 | |
| Age, Continuous | Years | 63.08 (SD 13.96) | 63.24 (SD 13.28) | 63.13 (SD 13.70) |
| Sex: Female, Male: Female | Participants | 189 | 112 | 301 |
| Sex: Female, Male: Male | Participants | 156 | 92 | 248 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Overall Survival (OS): Based on Treatment Cohort Groups, measured over From index date to the date of death due to any cause or censoring date, during data identification period of 9 years (retrieved data assessed in this observational study for approximately 3 months).
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | Years |
| Endpoint classification | Time-to-Event Analysis |
The primary endpoint is median overall survival, expressed in years. Overall survival is defined as time from the index date—the date of the first ALK TKI prescription—to death from any cause or a censoring date, defined as the latest date available in the data. The registry says the Kaplan–Meier method was used and that results were reported by treatment cohort group, with a 95% confidence interval for the median.
Overall survival is used in studies of this type because it records time to death from any cause, rather than relying on a judgment about the cause of death. Censoring allows people whose death was not observed by the end of available follow-up to contribute the time during which their status was known. In general, a survival estimate is most informative when its time origin, event definition, censoring rules, follow-up, and analysis population are clear. Here, the registry defines the time origin and event, but does not give the cohort-specific numbers analyzed, deaths, median estimates, or confidence intervals.
The endpoint can describe survival patterns in the observed treatment cohorts, but it does not by itself establish that one treatment sequence caused a different outcome. The registry record does not provide the outcome values needed to assess the observed survival pattern or its precision.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies median overall survival as the primary outcome and states that Kaplan–Meier analysis was used. However, it does not report median survival estimates, 95% confidence intervals, participant counts analyzed by cohort, or death counts for this outcome. Consequently, no cohort-specific survival estimate or comparison can be interpreted from the posted results. The presence of an endpoint definition is not a substitute for the numerical result.
The study’s stated purpose is to describe how ALK TKI treatments were sequenced in real-world Swedish practice and the outcomes associated with those sequences. The cohort definitions distinguish pathways involving chemotherapy, crizotinib, second-generation ALK TKIs, and lorlatinib. Without the group sizes and estimates, it is not possible to judge how common each pathway was, whether the groups had enough observed follow-up to estimate a median, or how precisely their survival was measured. The registry record does not report those details.
Even if cohort-specific survival values were available, an observational comparison would require cautious interpretation. Treatment sequences are not randomly assigned in the design described. People may enter different sequences because of clinical circumstances or prior treatment history, and those circumstances can also be related to survival. The registry record does not report an adjustment strategy or covariate-adjusted estimates. Therefore, it does not support attributing any difference between treatment cohorts to the sequence itself.
The record lists 27 outcome measures and no analysis entries. That combination does not establish that no analyses were performed; it means the registry record does not provide analysis entries from which results or methods beyond the outcome description can be assessed. It also does not report the number of eligible participants with complete information for each outcome. The enrollment of 549 should not be treated as the number analyzed for overall survival in every cohort.
The record’s summary describes the study as an exploration of real-world treatment sequencing. Its design can provide descriptive information about patterns of use and outcomes in the data that were assessed, if those results are reported. For the primary endpoint, however, the registry record gives the definition and method but not the estimates. Conclusions about the direction, magnitude, or precision of survival differences are therefore not available from this record.
9. Statistical Methods Explained
The outcome description names the Kaplan–Meier method and a median with a 95% confidence interval. Other details of the statistical plan are not reported in the registry record. The explanations below describe the general meaning of the named methods, rather than unreported choices made by the study team.
What does Kaplan–Meier estimation do?
In general, Kaplan–Meier estimation is a way to describe time until an event when participants have different lengths of observation. For this study, the event is death from any cause, and the time origin is the first ALK TKI prescription. People who are still alive at the latest available date are censored: their observed follow-up contributes information up to that date, but their later survival time is unknown. The method constructs an estimated survival curve from the observed event times while accounting for this incomplete follow-up.
Censoring is not the same as recording a death, and it does not mean that a participant experienced the event. In general, the interpretation of a Kaplan–Meier estimate relies on assumptions about how censoring relates to the event process. The registry record does not describe censoring patterns or report checks of those assumptions. It defines the censoring date as the latest available date in the data, but does not give the dates or follow-up distribution for each cohort.
What does the median mean?
In general, median survival is the time at which an estimated survival curve reaches the halfway point: the estimate divides the curve into an earlier and later portion of survival time. It is a summary of the estimated curve, not the average time lived, and it does not describe the experience of every participant. If the estimated curve does not reach the point needed to define a median during observed follow-up, a median may not be estimable. The registry record does not report whether the median was estimable for each treatment cohort.
A confidence interval describes uncertainty around an estimate under the statistical method used. In general, a 95% confidence interval represents a range of values compatible with the data and method, and wider intervals indicate less precision than narrower intervals. It is not a guarantee that the true value lies in the particular interval. Although the registry specifies a 95% confidence interval for the median, it does not report the interval endpoints, so the precision of the survival estimates cannot be assessed.
What do the cohort labels represent?
The listed groups are defined by treatment histories, not by random assignment. Group A1 includes chemotherapy, crizotinib, and any second-generation ALK TKI; A2 includes crizotinib and any second-generation ALK TKI. B1 adds another second-generation ALK TKI after chemotherapy, crizotinib, and a second-generation ALK TKI; B2 describes crizotinib, a second-generation ALK TKI, and another second-generation ALK TKI. C1 includes chemotherapy, crizotinib, any second-generation ALK TKI, and lorlatinib; C2 includes crizotinib, any second-generation ALK TKI, and lorlatinib. D1 includes any second-generation ALK TKI and another second-generation ALK TKI. These definitions identify broad pathways, but the registry record does not report the number of people in each group or the full operational rules used to assign people to them.
In general, comparisons across treatment-history groups can be affected by differences in who enters each group, when therapies occur, and how long people are observed. The record does not report an adjusted comparison or a causal analysis. It also does not state whether the groups were compared directly or whether the estimates were intended only as separate descriptions.
What is not specified about the analysis?
The registry record does not report the statistical analysis plan beyond naming Kaplan–Meier estimation for overall survival. It does not describe model assumptions, how confidence intervals were calculated, how missing data were treated, or whether any sensitivity analyses were conducted. It does not report interim analyses. The record also lists no analysis entries. These omissions prevent a detailed appraisal of implementation and do not justify assuming a particular method for choices that are not described.
The sample-size planning illustrations associated with the posted material are not observed power calculations. In general, a planning calculation asks what sample size might be needed under stated assumptions; it does not measure the probability that a completed study detected an effect. No planning estimate can replace the missing outcome counts and survival estimates. For this time-to-event outcome, the relevant information would include observed events and follow-up, but those values are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 27 outcome measures, including overall survival and several treatment-duration outcomes, and reports no analysis entries. With multiple outcomes or cohort comparisons, there can be more than one opportunity to identify an apparently notable result. In general, multiplicity procedures can help address the increased chance of false-positive findings across a family of tests. Whether such procedures were planned or used is not reported in the registry record. No adjustment strategy, hierarchy of outcomes, or prespecified comparison set is reported, so the family of analyses intended for formal inference cannot be established.
The registry does not report a missing-data method for the primary endpoint or secondary outcomes. For survival analysis, people with incomplete follow-up may be censored rather than treated as having had the event, but the handling of other unavailable information—such as treatment history or cohort assignment—is not described. The record defines the latest available date as the censoring date, but does not describe the amount or pattern of censoring. It also does not report sensitivity analyses for missing or incomplete records.
The outcome description says the analysis population included eligible participants whose data were retrieved from Swedish administrative registers and assessed, and that the analyzed count depended on treatment generation. The enrollment is 549, but the number evaluable for overall survival, the number in each cohort, and the number included for each secondary outcome are not reported in the registry record. Thus, the enrollment figure should not be interpreted as the denominator for every outcome.
The record does not describe a formal intention-to-treat population, which would generally apply to randomized treatment assignment. This study is observational and treatment allocation is not stated. Its exact analysis populations and exclusions are not reported in the registry record.
11. What the Result Does, and Does Not, Mean
The registry record establishes that the study was designed to examine real-world sequencing of ALK TKIs and describes overall survival as time from first ALK TKI prescription to death from any cause or censoring. It also states that Kaplan–Meier estimation was used and identifies treatment-history groups. Those details explain what the primary endpoint was intended to measure and how the cohorts were organized.
The record does not report numerical survival results. It therefore does not show the median overall survival for any cohort, the uncertainty around those medians, or whether the cohort estimates differ. It also does not report the number of deaths or the number of participants analyzed in each group. No conclusion about the direction or size of an outcome difference can be drawn from the endpoint definition alone.
Even a reported association between treatment history and survival would not, by itself, establish that treatment sequence caused the observed outcome. This is a retrospective observational study, not a randomized comparison. Treatment pathways may reflect participant characteristics and events occurring during care; the registry record does not report an adjustment strategy that would address such differences. The results, if available, would need to be interpreted in the context of those design limits.
The registry record also does not establish that all people with ALK-positive NSCLC in Sweden were represented, nor does it give enough detail to assess the completeness of register data or the representativeness of the analyzed population. The enrollment of 549 describes the registered study, not necessarily a complete national population or the number contributing to each result. The study’s real-world setting is relevant to describing observed practice, but does not remove uncertainty about selection, missing data, or confounding.
Accordingly, the most defensible reading is that the record describes a retrospective study question, endpoint, and method, but does not provide the primary numerical outcome needed to judge survival patterns or their precision. It should not be read as evidence for or against a particular treatment.
12. Why This Trial Matters Statistically
Real-world treatment often involves a sequence of therapies rather than a single isolated choice. A registry-based study can describe those pathways in routine practice and organize outcomes around treatment histories, which is a different question from a randomized comparison of assigned treatments. This study’s cohort definitions illustrate that distinction by combining chemotherapy, crizotinib, other second-generation ALK TKIs, and lorlatinib in varied sequences.
The statistical issue is that treatment history is also a marker of what happened to a participant over time. Groups formed from observed sequences may differ in clinical circumstances, prior treatments, and available follow-up. In general, such differences can complicate comparisons even when the outcome is measured consistently. Clear cohort definitions and transparent analysis populations are therefore important to interpreting real-world results. The registry supplies the broad definitions and names Kaplan–Meier estimation, but does not report cohort sizes, survival estimates, or adjustment methods.
The record also highlights the difference between registering an outcome and reporting a result. It describes median overall survival and a 95% confidence interval, yet does not give their values. Without estimates and uncertainty, readers cannot assess whether the data are informative, whether differences are precise, or how the observed outcomes varied across treatment sequences.
Statistically, the study is relevant as an example of a question that register data can address descriptively, while also showing why numerical results and analysis details are essential. Treatment sequencing is intrinsically longitudinal, and conclusions depend on how participants are classified, followed, and compared. Those details are not reported sufficiently in this registry record to support conclusions about comparative survival.
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 main limitation for interpreting the primary endpoint is that the registry record does not report its numerical results. Median overall survival, 95% confidence intervals, cohort-specific analysis counts, death counts, and follow-up distributions are not reported in the registry record. Without these, neither the magnitude nor the precision of the survival estimates can be assessed.
The study is retrospective and observational, with treatment cohorts defined by recorded treatment histories. The registry does not describe randomized allocation, and allocation is not stated. It also does not report an adjusted analysis, covariates, or a strategy for addressing differences between treatment cohorts. Any unadjusted contrast, if one were reported elsewhere, could reflect differences in the people or histories represented by each group as well as treatment sequence.
The registry gives an enrollment of 549 but does not report the cohort sizes or the outcome-specific analysis population. It describes an identification period of 9 years and says retrieved data were assessed for approximately 3 months, but does not give cohort-specific follow-up or censoring details. The record does not provide enough information to assess the completeness of register capture, the handling of incomplete treatment histories, or whether all relevant deaths were observed.
The entry lists 27 outcome measures and no analysis entries. It does not report how multiplicity was addressed, whether sensitivity analyses were performed, or whether the reported endpoint definition matches a detailed protocol. These are limitations of what can be evaluated from the registry record; they do not establish that the analyses were not performed. The record also does not explain the zero values listed in its adverse-event summary, so those entries should not be used to infer that no adverse events occurred.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Real-world Therapy of ALK-positive NSCLC in Sweden: the Sequencing of ALK Tyrosine Kinase Inhibitor Drugs and Their Therapeutic Outcomes Based on Data From National Registers. — NCT04647110.
- Registry record last updated 2023-04-06; status last verified 2023-04.
- Results first posted 2022-07-13.
- 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
This completed retrospective observational study examines ALK TKI sequencing and outcomes among people with ALK-positive NSCLC using Swedish administrative register data. The registry lists Pfizer as sponsor, enrollment of 549, and study dates from 2020-12-14 to 2021-03-15. The stated data identification period for the primary outcome is 9 years, with retrieved data assessed for approximately 3 months.
The primary outcome is median overall survival from first ALK TKI prescription to death from any cause or censoring, analyzed with Kaplan–Meier estimation and reported with a 95% confidence interval. Cohorts are defined by combinations of chemotherapy, crizotinib, other second-generation ALK TKIs, and lorlatinib. Secondary outcomes concern treatment duration across treatment cohorts, chemotherapy status, and numbers of ALK TKI treatment lines.
The registry lists 27 outcome measures and no analysis entries. Numerical overall-survival estimates, confidence intervals, and cohort-specific analysis counts are not reported in the registry record. Thus, the record describes the question and methods but does not allow the primary survival results to be evaluated.