Study of Coagulation Faction VIIa Variant Marzeptacog Alfa (Activated) in Adult Subjects With Hemophilia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Coagulation Faction VIIa Variant Marzeptacog Alfa (Activated) in Adult Subjects With Hemophilia (NCT04072237), a na phase 1 study. The primary outcome is Comparative MarzAA Activity by Dose Level/Stage - AUC0-∞ and AUC0-last.

2. Clinical Question

The central statistical question is therefore descriptive: how was marzeptacog alfa exposure characterized across the sequential dose stages, and how much information does the registry record provide about that characterization? The stated endpoint focuses on exposure over time rather than a clinical comparison of bleeding outcomes. Secondary outcomes listed in the record include pharmacokinetic measures such as Cmax, Tmax, clearance, volume of distribution, bioavailability, and mean residence time.

Because there was no randomized control arm, the stage comparisons should not be read as controlled estimates of treatment effect. Stage participation may also differ: the record gives 11 at risk in Stage 1 and 8 at risk in each later listed stage. It does not report why those counts differ, or provide numerical AUC results to evaluate the magnitude or precision of exposure changes.

3. Trial Design

This was a phase 1, open-label, sequential study sponsored by Catalyst Biosciences. The registry lists allocation as not applicable, masking as none, and the model as sequential. Enrollment was 11. The study status is completed; the recorded start date is 2019-09-24 and primary completion date is 2020-04-30.

The study summary describes a single intravenous dose of MarzAA followed by ascending single subcutaneous doses in adults with moderate or severe hemophilia A or B, with or without an inhibitor. The stage description lists an intravenous dose of 18 µg/kg for Stage 1, followed by subcutaneous dose stages. The adverse-event group titles, however, label Stage 1 as 18 µg/kg subcutaneous. These descriptions are inconsistent in the registry record; the route for Stage 1 therefore cannot be resolved from the record alone.

Later stage descriptions include 30 µg/kg, 45 µg/kg, 60 µg/kg, 2×30 µg/kg, 90 µg/kg, 120 µg/kg, 2×60 µg/kg Q3H, and 3×60 µg/kg Q3H. The study summary characterizes the doses as ascending single subcutaneous doses, while the later stage titles include repeated-dose schedules. The registry describes each stage's dosing period as approximately 3 days, with a maximum of approximately 8 weeks of dosing depending on participation in all 9 stages and the time between stages.

The primary endpoint was comparative pharmacokinetics by dose level or stage, using AUC0-∞ and AUC0-last. Secondary outcomes covered other pharmacokinetic measures, including intravenous-to-subcutaneous comparisons. The registry record does not report a parallel control group, a randomized allocation process, or masking. The listed stages thus describe a sequential dose evaluation rather than a randomized comparison between independent treatment arms.

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: Fourteen subjects were screened in the study and three subjects were screen failures. Two subjects failed due to having a known positive antibody at screening, and one subject failed screening due to other.

Stage I: MarzAA 18 µg/kg IV

Stage 2: MarzAA 30 µg/kg SC

Stage 3: MarzAA 45 µg/kg SC

Stage 4: MarzAA 60 µg/kg SC

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Comparative MarzAA Activity by Dose Level/Stage - AUC0-∞ and AUC0-last, measured over Dosing period for each stage was approximately 3 days, with a maximum of approximately 8 weeks of dosing, depending on participation in all 9 stages and time elapsed between each study stage..

The primary endpoint is titled “Comparative MarzAA Activity by Dose Level/Stage - AUC0-∞ and AUC0-last.” AUC, or area under the concentration-time curve, is a pharmacokinetic measure of drug exposure over time. In general, AUC0-∞ represents estimated exposure from dosing through an extrapolated infinite time, while AUC0-last represents exposure through the last observed measurement. These measures can help describe and compare exposure across dose levels or stages.

The registry specifies that the endpoint is expressed in h*ng/mL and reported as a mean with standard deviation. The outcome description says that pharmacokinetics were compared by dose level or stage based on examination of AUC frequencies for each dose group. This indicates an exposure-focused endpoint; it is not itself a direct measure of bleeding control or another clinical outcome.

Mean values describe the central level of exposure in the measured group, while standard deviations describe variation among measured values. Their interpretation depends on having the underlying numerical estimates and the number of observations contributing to each estimate. The registry record does not report the AUC means, standard deviations, or stage-specific analysis counts. It therefore does not permit a reader to assess the size or precision of differences in exposure across stages.

The stated timeframe spans the dosing period for each stage and varies with participation and elapsed time between stages. The record does not provide further detail about the measurement schedule or how missing pharmacokinetic measurements were handled.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Pharmacokinetic endpoints describe how drug concentrations change over time. AUC is a summary of exposure across a time interval. In general, a larger AUC indicates greater measured exposure over the interval being summarized, but interpretation depends on dose, route, timing, measurement quality, and the analysis used. The endpoint in this study is listed as mean AUC0-∞ and AUC0-last by dose level or stage, with standard deviation as the dispersion measure. The registry record does not give the values needed to examine those summaries.

What does a mean with standard deviation describe?

A mean is a measure of the center of a set of observations. A standard deviation describes how spread out individual observations are around that mean. It is not a confidence interval: it describes variability among observations, whereas a confidence interval is intended to express uncertainty about an estimated quantity. General statistical interpretation of a mean and standard deviation also depends on the number of observations and the shape of the data distribution. The record does not report stage-specific AUC means, standard deviations, or analysis counts, so none of those features can be assessed for this study.

Why does the sequential design matter?

In a sequential dose study, stages are undertaken in an ordered progression rather than as randomized parallel groups. The registry lists no random allocation and no masking. Consequently, stage-specific results would describe observations made at each dose stage, but a difference between stages would not by itself isolate a dose effect in the way a randomized comparison is designed to do. General considerations in sequential studies include the possibility that later-stage participants differ from earlier-stage participants and that conditions may change over time. The record does not report whether the same participants contributed measurements at every stage, or how any within-participant correlation was handled.

The stage listings show differing numbers at risk, but the record does not explain the variation. The number of participants at risk for safety reporting is not necessarily the number with usable pharmacokinetic measurements. General good practice is to report analysis counts and explain missing observations for each endpoint; these details are not reported in the registry record.

How should AUC0-∞ and AUC0-last be distinguished?

AUC0-last summarizes exposure from dosing through the last measured concentration. AUC0-∞ extends the summary beyond the last measurement by estimating the remaining exposure. Because the latter involves extrapolation, its interpretation depends in part on the terminal concentration-time information and estimation method. This is general pharmacokinetic context; the registry record does not describe the calculation details, the extrapolated fraction, or criteria for including an estimate.

What can be learned from the listed analyses?

The registry lists 23 outcome measures and zero analyses. This means the record identifies outcomes but does not list analysis entries for them. It does not report an inferential statistical plan, a model for stage comparisons, a method for handling repeated measurements, or an approach to uncertainty estimation. The primary endpoint specifies mean and standard deviation, but those descriptive choices alone do not define a complete analysis plan.

The registry's sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such illustrations are hypothetical planning calculations, not observed power and not evidence that the study was designed or powered using those assumptions. Because the study is sequential and does not have a randomized two-arm comparison, those generic assumptions should not be mistaken for the study's actual design. The record does not report the study's sample-size justification or a statistical plan tied to the sequential stages.

In general, confidence intervals communicate the range of values reasonably compatible with an estimate under a statistical model; they are useful for judging precision alongside the estimate itself. The registry record does not report confidence intervals for the primary endpoint. Without numerical estimates and uncertainty measures, readers cannot determine whether stage-specific exposure summaries are precise or highly variable. The absence of a reported analysis is not evidence that no analysis was conducted outside the registry; it means the analysis details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 23 outcome measures, including the primary AUC endpoint and secondary pharmacokinetic outcomes such as Cmax, Tmax, half-life measures, clearance, volume of distribution, bioavailability, and mean residence time. It lists zero analyses. The registry record does not report a multiplicity strategy, such as whether any outcomes were designated for formal hypothesis testing, whether tests were prioritized, or whether adjustments for multiple comparisons were planned.

Multiplicity is a general statistical concern when several outcomes or comparisons are examined: the more opportunities to identify an apparently notable result, the more important it is to specify which questions are confirmatory and how uncertainty will be interpreted. Here, the record does not provide analysis results or a statistical analysis plan that would show how this issue was addressed. The list of outcomes alone does not establish that each was tested.

Missing-data handling is also not reported in the registry record. The stage-specific safety listings give at-risk counts, but do not explain why those counts differ or identify the number contributing to each pharmacokinetic endpoint. The record does not state how incomplete concentration profiles, missing visits, or unevaluable AUC estimates were handled. It also does not describe whether analysis populations were defined for the primary or secondary outcomes.

These omissions limit interpretation of both the reported design and any potential stage comparisons. Without analysis populations, endpoint-specific counts, and missing-data methods, a reader cannot determine how the analyzed observations relate to enrollment or stage participation. No assumptions about imputation, exclusion, or participant completion can be made from 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 serious adverse-event counts separately for each stage. No participants are listed as affected by a serious adverse event in any stage, and deaths are listed as zero throughout. The record also lists no serious adverse-event terms. These are the posted counts, not proof that serious events are impossible or that the treatment is free of risk.

Other adverse events are reported as affected participants in Stage 2 (3), Stage 4 (1), Stage 5 (1), Stage 7 (2), Stage 8 (3), and Stage 9 (2). Stage 1, Stage 3, and Stage 6 list zero affected by other adverse events. The at-risk count is 11 for Stage 1 and 8 for each later stage. These stage-specific entries should not be added together to infer a total number of distinct participants, because the registry describes a sequential study and does not clarify participant overlap across stages.

These figures are descriptive. With no randomized control arm, they do not provide a controlled comparison of adverse-event risk. The registry record does not report event types for the non-serious adverse events in these listings, their severity, timing, or whether they were judged related to treatment. It also does not explain the difference in at-risk counts across stages.

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

The record establishes that a completed phase 1 study evaluated marzeptacog alfa in adults with hemophilia and defined pharmacokinetic exposure as its primary endpoint. It describes a sequential progression through dose stages and records safety counts by stage. Those details identify the study's focus and the structure of the available registry information.

The record does not report the numerical AUC0-∞ or AUC0-last results, despite naming them as the primary endpoint. It therefore cannot show the size or precision of observed exposure at each stage, or how exposure compared across stages. The listed endpoint definition is not itself a result. Nor does the record supply the inferential analyses, confidence intervals, or analysis populations needed to evaluate statistical uncertainty.

The safety listings show no serious adverse events or deaths recorded in the stage groups, alongside other adverse-event counts in some stages. These are descriptive reports and cannot establish a comparative safety profile without a suitable control comparison and fuller details. They also do not justify a claim that no serious events occurred outside the reported record.

More broadly, a pharmacokinetic study addresses drug exposure and related measures, not necessarily clinical outcomes. The primary endpoint does not directly quantify bleeding outcomes. The registry information therefore cannot support a conclusion about clinical benefit or lack of benefit. It also cannot establish a causal dose-response relationship from the sequential stage listings alone.

The appropriate reading is limited: the registry describes the population, intervention sequence, endpoint, and available safety counts, but does not provide the primary numerical outcome results or enough analysis detail to assess exposure patterns and their precision. Missing information should be treated as unreported, not as evidence for a particular result.

13. Why This Trial Matters Statistically

This study is statistically notable for the contrast between a clearly identified pharmacokinetic question and the limited results reported in the registry. AUC0-∞ and AUC0-last are specified as the primary measures, with mean and standard deviation as summary statistics. Yet the registry record does not include their numerical estimates. Readers can identify what the study intended to characterize, but cannot assess the observed exposure pattern or its precision from the record.

The sequential design is also important to interpretation. Dose stages can be useful for describing pharmacokinetics during an ascending-dose evaluation, but the stages are not randomized control groups. The absence of allocation and masking details beyond the registry's entries means that stage comparisons should not be presented as controlled treatment effects. The record's inconsistent route description for Stage 1 further illustrates why precise reporting of intervention details matters.

The registry lists many outcome measures but no analysis entries. This makes it difficult to distinguish descriptive objectives from formal inferential questions, or to understand how multiplicity, missing measurements, and repeated observations were handled. Such information helps readers judge whether reported estimates answer the study's stated questions and how much uncertainty surrounds them.

Finally, the stage-specific safety counts communicate what was recorded while leaving important context unreported, including event descriptions and reasons for differing at-risk counts. Transparent outcome estimates, endpoint-specific analysis counts, and clear statistical methods would allow a more complete appraisal. In their absence, the record supports a careful account of design and reporting limits rather than broad conclusions about pharmacokinetics or clinical effects.

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 primary limitation of the registry record is that it does not report numerical results for the primary AUC endpoint. Means, standard deviations, analysis counts, and uncertainty estimates are absent, preventing assessment of the observed exposure levels and their precision. Although secondary pharmacokinetic outcomes are listed, their numerical results and analyses are also not reported in the registry record.

The study is sequential, open label, and has no randomized control arm. Stage comparisons are therefore not randomized comparisons, and the registry does not describe an adjustment strategy for differences across stages or repeated measurements. The record does not report whether the same participants completed every stage or how participation changed over time.

There is an internal discrepancy about Stage 1 route: the arm description identifies an intravenous dose, while the adverse-event group title identifies a subcutaneous dose. The description also refers to single subcutaneous doses, while later stage titles include repeated-dose schedules. These details cannot be reconciled using the registry record alone.

The record does not report the statistical analysis plan, sample-size justification, analysis populations, missing-data methods, multiplicity handling, or endpoint-specific sample counts. It also does not give reasons for the difference in stage-specific at-risk counts. For safety, the registry lists affected counts but does not report non-serious event terms, severity, timing, or treatment attribution. These limitations restrict interpretation to the design and counts explicitly recorded, without supporting conclusions about comparative effects or clinical outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Coagulation Faction VIIa Variant Marzeptacog Alfa (Activated) in Adult Subjects With Hemophilia — NCT04072237.
• Registry record last updated 2021-09-13; status last verified 2021-09.
• Results first posted 2021-07-16.
• 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

NCT04072237 is a completed phase 1, open-label, sequential study sponsored by Catalyst Biosciences. It enrolled 11 adults with hemophilia and evaluated marzeptacog alfa through an intravenous and ascending subcutaneous dose-stage program. The record describes the primary pharmacokinetic endpoint as mean AUC0-∞ and AUC0-last by dose level or stage, with standard deviation.

The registry lists 23 outcome measures and zero analyses. Numerical primary endpoint results and analysis details are not reported in the registry record. Stage-specific safety listings report zero participants affected by serious adverse events and zero deaths; other adverse-event counts are listed for several stages. Stage 1 route descriptions are inconsistent in the record. The design and available counts can be described, but the posted information does not permit evaluation of the primary exposure results or a controlled comparison.