A Study in Healthy Men to Compare 2 Different Formulations of Alteplase: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study in Healthy Men to Compare 2 Different Formulations of Alteplase (NCT04419493), a randomized phase 1 study. The primary outcome is Part A: Area Under the Concentration-time Curve of Alteplase in Plasma Over the Time Interval From 0 up to the Last Quantifiable Data Point (AUC0-tz).

2. Clinical Question

3. Trial Design

The registry identifies this as a Phase 1, randomized, open-label crossover study sponsored by Boehringer Ingelheim. It enrolled 30 participants and is marked completed. The recorded study start date is 2020-06-23, and the primary completion date is 2021-06-21. Participants were healthy men, rather than patients being treated for a clinical condition.

The study compared alteplase associated with two manufacturing processes. The registry lists alteplase from a modified manufacturing process and alteplase from the current manufacturing process. Arm descriptions use the labels TPA-02 and TPA-05 and describe sequences in which each product is administered before the other. Part A includes sequences labelled TPA-05 then TPA-02 and TPA-02 then TPA-05. Part B also includes both sequence orders. The record does not explain the relationship between the TPA codes and the named manufacturing processes, or report the allocation of participants to each sequence.

In a crossover design, the treatment sequence is part of the comparison: participants receive treatments in different periods rather than remaining in only one treatment group. This can support within-participant comparisons, although interpretation can depend on period effects, sequence effects, and any carryover between periods. Those design details and the methods used to address them are not reported in the registry record. The record identifies masking as none, consistent with an open-label study.

Unfractionated heparin is also listed as an intervention, but its role and use are not described in the registry record. The record lists six outcome measures and three analyses, but their full definitions and analysis details are not available in the information reported for this trial. The registry does not report the planned sample-size justification, the randomization procedure, or a detailed statistical analysis plan.

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: All subjects were screened for eligibility prior to participation in the trial. Subjects attended a specialist site which ensured that they (the subjects) strictly met all inclusion and none of the exclusion criteria. Subjects were not to be allocated to a treatment group if any of the entry criteria were violated. In this cross-over trial 2 single doses of alteplase were infused on 2 consecutive days keeping a wash-out period of at least 24 h.

Period 1

Wash-out After Period 1

Reasons for not completing this period:

Period 2

Analysis population for the primary outcome, as defined in the registry: Pharmacokinetic parameter analysis set - part A (PKS-A): Includes all subjects in the treated set - part A (TS-A) who provide at least one PK endpoint that was defined as primary or secondary and was not excluded due to a protocol violation to the evaluation of PK or due to PK non-evaluability. PK data for Part A were not used for the final assessment of bioequivalence according to protocol amendment after obtaining unreliable PK results.

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: Treated set - part A (TS-A) included all subjects who were randomised and treated with at least 1 dose of the investigational medicinal product. Treated set - part B (TS-B) included all subjects who had been randomised and treated with at least 1 dose of the investigational medicinal product.

6. Primary Endpoint

The registry lists the primary outcome as Part A: Area Under the Concentration-time Curve of Alteplase in Plasma Over the Time Interval From 0 up to the Last Quantifiable Data Point (AUC0-tz), measured over Within 3 hours (h) before and 5 minutes (min), 10min, 15min, 20min, 25min, 30min, 32min, 34min, 36min, 40min, 45min, 50min, 1h, 1.33h, 1.67h, 2h, 3h, 4h and 6h after start of alteplase infusion..

The primary endpoint is Part A AUC0-tz: the area under the plasma alteplase concentration-time curve from time zero to the last quantifiable data point. The registry specifies sampling before and after the start of alteplase infusion, with observations extending through 6h after infusion start. The concentration-time curve represents how measured drug concentrations change over time; its area combines concentration and duration into a measure of exposure during the quantifiable interval.

Exposure measures are used in pharmacokinetic comparisons because formulations that produce similar concentration profiles may also produce similar overall exposure. AUC0-tz is limited to the last quantifiable data point, so it is distinct from an area extrapolated to infinity. The registry separately lists AUC0-∞ as a secondary outcome for both Part A and Part B. These endpoints use different time intervals and should not be treated as interchangeable.

As a general statistical point, a bioequivalence assessment usually considers the estimated relative exposure and its uncertainty against a prespecified acceptable range. The registry record does not report the acceptable range, the estimate for AUC0-tz, its confidence interval, or the primary comparison’s result. The endpoint definition alone therefore explains what was intended to be measured, but cannot indicate whether the study met its stated aim.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies randomization, no masking, and a crossover model. These labels describe different aspects of design. Randomization concerns how treatment sequences are assigned; masking concerns whether treatment identity is concealed; and crossover indicates that treatment order is part of the study structure. The registry does not describe the randomization method, concealment procedures, or operational details of the treatment periods.

What does crossover mean for analysis?

General explanation: in a crossover study, a participant may contribute measurements under more than one treatment. The comparison can therefore use within-participant information, which may reduce the influence of stable differences between participants. This does not remove all design or analysis concerns. Treatment period, sequence, changes over time, and possible carryover can affect the measured response. Statistical methods may account for these features, but the particular model and any carryover assessment are not reported in the registry record. The presence of a crossover design alone does not reveal which model was used.

The registry names sequences with TPA-02 and TPA-05 in both Parts A and B. The arm descriptions do not map those labels to the modified and current manufacturing processes. Nor do they specify the timing between periods or any washout procedure. Those details are important for understanding how the paired treatment measurements were obtained and compared, and are not reported in the registry record.

What does AUC measure?

General explanation: area under a concentration-time curve condenses a series of measured concentrations across time into an exposure summary. AUC0-tz ends at the last quantifiable data point, whereas AUC0-∞ extends the calculation beyond the observed profile through an extrapolation. The registry lists AUC0-tz as the Part A primary endpoint and AUC0-∞ as a secondary outcome in both parts. It describes plasma concentration sampling from before infusion through 6h after infusion start. The record does not report the concentration values, the AUC estimates, or the method used to calculate the area.

For a bioequivalence assessment, investigators commonly compare exposure between formulations using a specified statistical scale and judge uncertainty against prespecified limits. This is general methodological context, not a description of the analysis used in this trial. The registry record does not report the scale, transformation, equivalence limits, confidence-interval procedure, or decision rule. Without those details and the results, the endpoint name cannot establish the statistical conclusion.

Why does uncertainty matter?

General explanation: an estimate summarizes the observed comparison, while a confidence interval communicates its precision under the analysis assumptions. In an equivalence setting, the question is not simply whether a conventional test finds a difference. The analysis must also show that plausible values for the comparison remain within a prespecified range judged acceptable for the purpose. A result can be inconclusive if its uncertainty is too broad, even when its point estimate appears close to the target. The equivalence range and interval for this trial are not reported in the registry record.

Dispersion is another consideration. General explanation: when observations vary more than a simple model assumes, standard errors and confidence intervals can be misleading if the analysis does not account for that variability. Methods that accommodate over-dispersion or other departures from model assumptions may be appropriate in some settings, but whether such issues arose, and how they were handled in this trial, is not reported in the registry record. No dispersion estimate for the primary endpoint is reported in the available information.

How should planning calculations be read?

The stated planning illustration assumptions refer to a two-sided significance level of 0.05, equal allocation, and a normal approximation. They describe planning calculations based on an observed effect and a chosen fraction of that effect. Such calculations are not observed power: they ask how many participants per arm might be needed under specified assumptions for a future or hypothetical design. The numerical planning outputs and the effect used for the illustration are not reported in the information available for this analysis. The registry’s original sample-size justification is not reported in the registry record.

The crossover design also means that simple equal-allocation assumptions may not describe the actual sequence structure. The planning statement is a general illustration and should not be interpreted as the trial’s enrollment plan. The registry reports 30 enrolled, but the record does not provide the rationale for that number in the information.

What can be inferred from the listed analyses?

The registry lists three analyses and six outcome measures. Those counts do not identify the analytical models, estimands, adjustment variables, or hierarchy among outcomes. The record does not report whether analyses were prespecified, whether any interim analyses occurred, or how protocol deviations and missing measurements were handled in each analysis. These omissions prevent a complete reconstruction of the inferential method from the design and endpoint descriptions alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and three analyses. The primary endpoint is identified as Part A AUC0-tz, while AUC0-∞ is listed as a secondary outcome in both Part A and Part B. The available record does not describe a hierarchy among all outcomes, a familywise error strategy, or any adjustment for multiple comparisons. The prespecified multiplicity approach is not reported in the registry record.

Multiplicity matters when several outcomes or comparisons are examined because repeated inferential testing can increase the chance of at least one apparently notable result arising by chance. This is a general statistical concern, not a claim about what occurred in this trial. Without the analysis plan and complete endpoint results, it is not possible to determine which comparisons were confirmatory, whether adjustments were made, or how any secondary findings should be interpreted relative to the primary objective.

The primary population description states that the Part A pharmacokinetic analysis set includes treated participants who provide at least one primary or secondary pharmacokinetic endpoint and whose endpoint is not excluded for a protocol violation affecting pharmacokinetic evaluation or for pharmacokinetic non-evaluability. The registry description ends before providing further detail. The full definition, the number included in that set, and the handling of missing measurements are not reported in the registry record.

General explanation: missing data can affect an estimate when the probability of a measurement being missing relates to the participant’s response or treatment experience. Analysis choices depend on the pattern and reason for missingness, as well as the endpoint and design. The registry information does not describe missing-data assumptions, imputation, sensitivity analyses, or participant flow by analysis population. The planned approach to protocol deviations and exclusions beyond the stated population description is also not reported in the registry record.

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 non-serious adverse event terms

The registry reports safety counts separately for Part A and Part B and for the TPA-02 and TPA-05 groups. For Part A TPA-02, 10 participants were at risk for the listed safety assessment; 0 had a serious adverse event, and 1 was affected by another adverse event. For Part B TPA-02, the corresponding counts are 18 at risk, 0 with a serious adverse event, and 7 affected by another adverse event. For Part A TPA-05, the counts are 11 at risk, 0 with a serious adverse event, and 4 affected by another adverse event. For Part B TPA-05, they are 17 at risk, 0 with a serious adverse event, and 6 affected by another adverse event.

The record reports zero deaths in each group and lists no top serious adverse-event terms. These are counts of participants affected, not a complete description of event types, severity, timing, or relatedness. The registry record does not explain why the numbers at risk differ across groups or how safety follow-up was defined. The TPA labels are not mapped to the manufacturing processes in the arm descriptions, so the safety counts should not be attributed to the modified or current process without that mapping.

These figures describe the entries in the registry; they do not by themselves establish comparative safety. The study was a crossover trial in healthy men, and the available safety information is limited to the listed counts. More detailed adverse-event definitions and results are not reported in the registry record.

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

The trial addresses a focused pharmacokinetic question: whether alteplase from two manufacturing processes has comparable exposure in healthy male volunteers. The primary endpoint, AUC0-tz, is suited to describing exposure over the quantifiable plasma concentration profile. The randomized crossover design is relevant because it permits treatment sequence comparisons within the study framework. These design features explain the question being asked, but do not supply the answer.

The key limitation for interpretation is that the registry record does not report the numerical primary endpoint result. There is no primary estimate, confidence interval, or stated bioequivalence conclusion in the information available for this analysis. The equivalence margin and the statistical decision criteria are also not reported. As a result, the stated aim cannot be treated as a finding, and the design cannot be used to infer that bioequivalence was established.

The listed secondary exposure outcomes do not resolve this gap because their numerical results are not reported in the available information either. The safety entries show zero serious adverse events and zero deaths in each listed group, alongside participants affected by other adverse events. They are descriptive counts and do not answer the exposure comparison. They also should not be generalized beyond the study population and the recorded follow-up.

General explanation: evidence of equivalence requires attention to both the comparison estimate and its precision relative to an acceptable range defined in advance. Failure to report a result is different from a result showing a difference, and it is also different from a result demonstrating equivalence. The registry information supports neither a positive nor a negative conclusion about the primary bioequivalence question.

The study’s enrollment of 30 and its healthy-volunteer setting describe the trial context. The registry record does not report how enrollment was justified, the number included in each pharmacokinetic analysis, or detailed handling of missing data. Those absences further limit assessment of precision and generalizability. The most defensible reading is therefore that the record establishes the intended comparison, design, and endpoint, while leaving the central statistical result unreported.

13. Why This Trial Matters Statistically

This trial is statistically notable because it frames a manufacturing-process comparison as a pharmacokinetic bioequivalence question. That shifts attention from whether a treatment has an effect against no treatment to whether exposure measurements for two formulations are sufficiently comparable under a defined criterion. The distinction matters: an ordinary test for a difference and an equivalence assessment answer different questions.

The crossover structure is also important. General explanation: when participants receive both treatments in sequence, within-participant comparisons can account for stable differences between participants. At the same time, sequence, period, and carryover considerations may affect the analysis. The registry identifies the crossover model and treatment sequences but does not report the analysis approach or period-related details. Those omissions illustrate why a design label is not enough to reconstruct the statistical evidence.

The chosen primary endpoint, AUC0-tz, represents exposure through the last quantifiable concentration point. The registry also lists AUC0-∞ as a secondary measure, which reflects a different exposure interval. Distinguishing these measures is important because endpoint definitions determine what part of the concentration-time profile is summarized and what assumptions may enter the calculation.

The record also illustrates the difference between a trial objective and an observed result. It states an aim to establish bioequivalence, yet the numerical primary comparison, its uncertainty, and its decision criteria are not reported in the available information. A clear objective and a completed study do not substitute for effect estimates and uncertainty when assessing an inferential claim.

Finally, the listed safety counts provide a compact account of serious events, deaths, and other affected participants, but their interpretation is limited without fuller event descriptions and population details. The trial is therefore a useful example of how registry design information can clarify a statistical question while leaving central result and analysis details unresolved.

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 most consequential trial-specific limitation in the registry information is the absence of numerical primary endpoint results. AUC0-tz is defined, but its estimate, uncertainty, and conclusion are not reported in the registry record. The equivalence limits and decision rule are also not reported, preventing assessment of whether any result would satisfy the stated aim.

The record describes the study as randomized and crossover, and lists both treatment sequence orders in Parts A and B. It does not report the randomization method, allocation by sequence, period timing, washout details, or statistical handling of sequence and period effects. TPA-02 and TPA-05 are not mapped to the named manufacturing processes in the arm descriptions. The role of listed unfractionated heparin is also not reported in the registry record.

The primary pharmacokinetic population description is incomplete. It gives inclusion conditions involving treatment, endpoint availability, protocol violations, and pharmacokinetic evaluability, but the description is truncated. The analysis-set size, missing-data approach, sensitivity analyses, and participant flow are not reported in the registry record.

Although the record lists six outcomes and three analyses, it does not describe the full analysis plan, multiplicity approach, interim analyses, or sample-size justification. The safety information is limited to group counts and does not provide detailed event terms beyond the absence of listed serious-event terms. These limitations concern what can be evaluated from the registry information and should not be mistaken for evidence that a particular method or result was absent from the full study documentation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study in Healthy Men to Compare 2 Different Formulations of Alteplase — NCT04419493.
• Registry record last updated 2023-04-26; status last verified 2023-04.
• Results first posted 2023-04-26.
• 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 record describes a completed Phase 1 randomized, open-label crossover study sponsored by Boehringer Ingelheim. It enrolled 30 healthy male volunteers and compared alteplase associated with modified and current manufacturing processes. The study’s stated aim was to establish bioequivalence.

The primary endpoint was Part A plasma AUC0-tz, with AUC0-∞ also listed as a secondary outcome in Parts A and B. The registry names TPA-02 and TPA-05 treatment sequences but does not map those labels to manufacturing processes in the arm descriptions. Unfractionated heparin is listed as an intervention, though its role is not described.

The record reports zero serious adverse events and zero deaths in each listed safety group, with other adverse events affecting participants in all four groups. Numerical results for the primary endpoint, its uncertainty, the bioequivalence limits, and the primary conclusion are not reported in the registry record. Detailed analysis, missing-data, multiplicity, and sample-size justification information is also not reported in the registry record.