A Study of APL-9 in Adults With Mild to Moderate ARDS Due to COVID-19: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of APL-9 in Adults With Mild to Moderate ARDS Due to COVID-19 (NCT04402060), a randomized phase 1, phase 2 study. The primary outcome is Number of Subjects Who Experienced Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs.

2. Clinical Question

The study rationale describes complement activation as a possible contributor to inflammation in the lungs during COVID-19. APL-9 was designed to inhibit part of the complement pathway. That rationale gives context for the intervention but does not establish a clinical benefit. The study also listed outcomes including hospital length of stay, overall survival, changes in SOFA score, duration of mechanical ventilation and oxygen therapy, APL-9 concentration, and complement biomarkers. Their inclusion indicates areas of assessment, not evidence of a particular result.

3. Trial Design

This was a randomized, parallel-group phase 1/phase 2 study with an enrollment of 72. The registry record lists triple masking. Its study description characterizes Part 1 as open-label and Part 2 as double-blind and randomized. These descriptions differ in their wording about masking; the record does not explain that difference, so the masking procedures should not be inferred beyond what is stated.

Part 1 evaluated safety, with all participants receiving APL-9 plus standard of care. Part 2 compared APL-9 plus standard of care with vehicle control plus standard of care. The Part 2 arm descriptions identify 180 mg APL-9 intravenously in one arm and isotonic saline in the control arm. The record describes the study as multicenter. It does not report the number or locations of centers in the information available for this analysis.

The study began on 2020-05-28, had primary completion on 2021-02-13, and is listed as completed. The reported primary outcome concerned the number of participants experiencing TEAEs and serious TEAEs. Its follow-up ran from the first dose through 30 (+7) days after the last dose. The stated windows were Day 1 up to Day 44 for Part 1 and Day 1 up to Day 58 for Part 2.

The trial included multiple secondary outcomes spanning clinical status, resource use, survival, drug concentration, and biomarkers. The registry record lists 18 outcome measures and 4 analyses, but does not report a sample-size justification, allocation ratio, or detailed statistical analysis plan in the information.

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: The study was conducted in 2 parts: Subjects in Part 1 received open-label APL-9 from Day 1 through Day 7 or resolution of ARDS. Subjects in Part 2 were randomly assigned 1:1 to blinded treatment with either APL-9 or vehicle control from Day 1 through Day 7 or up to and including Day 21, discontinuation of respiratory support or hospital discharge, whichever occurred latest. Extended treatment beyond Day 7 in Part 2 required certain criteria to be met and was at discretion of the Investigator.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The safety set included all subjects who received at least 1 dose of study drug. Subjects were analyzed according to the actual treatment they received.

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: The safety set included all subjects who received at least 1 dose of study drug. Subjects were analyzed according to the actual treatment they received.

6. Primary Endpoint

The registry lists the primary outcome as Number of Subjects Who Experienced Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs, measured over From the first dose of study drug and up to 30 (+7) days after the last dose of study drug. Part 1: Day 1 up to Day 44; Part 2: Day 1 up to Day 58.

The primary outcome counted participants who experienced treatment-emergent adverse events and serious TEAEs. A TEAE was defined as an adverse event that developed or worsened in severity after the first dose and through 30 (+7) days after the last dose. A serious TEAE was an event or suspected adverse reaction that, in the view of the Investigator or Sponsor, resulted in death, was life-threatening, led to inpatient hospitalization or prolonged an existing hospitalization, caused persistent or significant incapacity or substantial disruption of normal life functions, or involved a congenital anomaly or birth defect.

Counting participants with events is a way to describe how many people in each treatment group experienced an event during the specified follow-up. It differs from counting every event: one participant may experience more than one event, while a participant count records whether each person experienced an event. The registry record defines the primary outcome in terms of participants, and its safety population includes those who received at least one dose, classified by actual treatment received.

In general, safety outcomes are important in studies of an investigational intervention because they describe adverse experiences during treatment and follow-up. They do not, by themselves, establish that an event was caused by the study drug. The registry record's definition includes events assessed by the Investigator or Sponsor, but the figures alone do not establish causality. The primary endpoint does not directly measure improvement in ARDS, oxygen needs, or survival.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count show?

The primary outcome is expressed as the number of participants experiencing TEAEs and serious TEAEs. A participant count answers whether people in a group experienced at least one event meeting the outcome definition. It is not the same as a total event count, because a participant can have multiple events. In general, event counts and participant counts answer different questions; the registry record defines this primary measure as a participant count.

The at-risk counts give the number of participants represented in each reported group for these safety outcomes. They provide context for the affected-participant counts. Small groups can make descriptive counts particularly sensitive to the experience of individual participants. That is a general statistical consideration, not a separate finding about this trial.

Why distinguish serious from other adverse events?

The record defines serious TEAEs by specified consequences, including death, life-threatening events, hospitalization or prolonged hospitalization, substantial or persistent functional impact, and congenital anomaly or birth defect. The seriousness classification is therefore based on the definition and assessment stated in the record; it is not a measure of how often an event occurred or proof that treatment caused it. The reported serious-event and other-event counts should be interpreted as separate categories rather than combined into a newly calculated total.

What can randomization contribute?

In general, random assignment is intended to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics. This supports a fairer treatment comparison than a nonrandomized allocation, but it does not ensure that groups are identical, especially when the groups are limited in size. Part 2 is described as randomized; Part 1 is described as open-label and all participants received APL-9. The registry record does not report the method used to generate or conceal the random sequence, so those procedures cannot be characterized further.

What is the role of blinding?

In general, masking can reduce the influence of expectations on care, event reporting, and outcome assessment. The registry record lists triple masking, while its narrative describes Part 2 as double-blind and Part 1 as open-label. It does not explain how the masking labels relate to the study procedures or which roles were masked. No further interpretation of the masking arrangement is warranted from the recorded descriptions alone.

How should estimates and uncertainty be read?

In general, a confidence interval expresses uncertainty around an estimated quantity: narrower intervals indicate greater precision, while wider intervals indicate less precision. A p-value is one way to summarize how compatible data are with a specified statistical null model, but it does not measure the probability that a treatment works or that a result is true. The registry record does not report confidence intervals or p-values for the listed primary safety counts. Consequently, the counts can be described, but their statistical precision and formal comparative evidence cannot be assessed from these figures alone.

What does a planning illustration mean?

The study information describes sample-size illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the trial was designed around that effect. The record does not report the trial's own sample-size justification in the information. No planning value should be interpreted as an observed trial result.

Why might event data require care?

In general, adverse-event data can be difficult to compare when event definitions, exposure time, or follow-up differ. This study specifies its TEAE definition and follow-up windows, with separate timeframes for Part 1 and Part 2. That detail helps establish what periods the primary outcome covers, but it does not establish that the groups had identical exposure or observation time. The registry record does not report additional adjustments for exposure time in the available information.

In general, over-dispersion matters when a statistical model assumes that variability is lower than the variability present in the data; under that mismatch, standard errors may be too small and uncertainty may be understated. The primary outcome is a participant count, and the registry record does not report a model or an over-dispersion assessment for it. This general concept should not be mistaken for a claim that over-dispersion affected this analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 18 outcome measures and 4 analyses, including the primary safety outcome and secondary measures of survival, hospital stay, SOFA score, durations of ventilation and oxygen therapy, drug concentration, and complement biomarkers. Considering many outcomes can raise a multiplicity issue: in general, the more statistical comparisons made, the greater the chance of at least one apparently unusual result arising by chance. Whether and how to address that issue depends on the prespecified analysis plan. The record does not report a multiplicity adjustment or a hierarchy for interpreting these outcomes.

The information available does not report confidence intervals, p-values, or a detailed statistical analysis plan for the primary safety comparisons. It also does not describe interim analyses or a sample-size justification. These details are not reported in the registry record, so no assumptions should be made about whether analyses were planned, adjusted, or conducted in a particular way.

The safety population is defined as all participants who received at least one dose of study drug, analyzed according to actual treatment received. This is an exposed safety population, not necessarily the same analysis population used for every other outcome. The registry record does not report how missing safety observations were handled, whether any participants had incomplete follow-up, or what analysis populations were used for the secondary outcomes. Missing-data methods can affect interpretation when participants have different amounts of observed information; in general, the extent and handling of missingness should be reported to assess that possibility.

The record's stated primary outcome covers the specified follow-up after first and last doses. It does not provide a detailed account of censoring, imputation, or sensitivity analyses for the reported safety counts. Without those details, the counts remain descriptive and their sensitivity to incomplete follow-up cannot be evaluated.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: respiratory failure (16.7%), acute kidney injury (16.7%), dyspnoea (12.1%), septic shock (12.1%), acute respiratory failure (9.4%).

The serious adverse-event counts are 1 participant among 6 at risk in Part 1: APL-9, 14 among 33 in Part 2: APL-9, and 15 among 32 in Part 2: Control. The counts for other adverse events are 3 among 6, 20 among 33, and 20 among 32, respectively. The listed deaths are 1, 13, and 8 in those same groups. These figures describe participants in the reported groups; they are not a formal comparison of treatment effects.

Part 1 was open-label and had no control arm described, while Part 2 was randomized and included a vehicle-control group. Comparisons between the Part 2 arms are more directly relevant to the randomized contrast, but the reported counts alone do not show the uncertainty around a difference or establish causation. The registry record does not report confidence intervals, p-values, or a formal adjusted analysis for these counts.

The serious-event terms and percentages are also descriptive. Respiratory failure and acute kidney injury are each listed at 16.7%; dyspnoea and septic shock at 12.1%; and acute respiratory failure and hypoxia at 9.4%. The denominator and percentage basis are not reported in the registry record, so these percentages should not be interpreted as group-specific risks. A serious event or death recorded during follow-up is not, by itself, evidence that study treatment caused it.

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

The results describe adverse experiences observed among participants who received study drug, using the registry's safety population and event definitions. They show that serious and other adverse events, as well as deaths, were recorded in each reported group. The counts are relevant to understanding what happened during the study's follow-up, but they do not on their own establish why an event occurred.

Part 2 included randomized APL-9 and vehicle-control groups, which supports a comparative design. Still, the reported counts are not accompanied in the available record by confidence intervals, p-values, or a formal effect estimate. Without those, the precision of a difference and the strength of statistical evidence cannot be judged from the counts alone. Part 1 was open-label and had no control group described, so its findings are descriptive rather than a controlled comparison.

The primary outcome is safety-focused. Although the study listed secondary clinical outcomes such as overall survival, hospital length of stay, SOFA score, and duration of oxygen therapy or mechanical ventilation, their results are not reported in the registry record summarized in the available information. The presence of those outcomes in the study record should not be treated as a result or as evidence of improvement.

The recorded deaths and serious adverse events also do not establish treatment causality. The record describes seriousness criteria and the period for collecting TEAEs, but the counts alone do not distinguish events caused by the intervention from events due to the underlying illness or other causes. A causal interpretation would require information beyond these descriptive figures and a suitably reported analysis.

Accordingly, the data support a description of the safety events recorded in the study groups. They do not, on their own, show whether APL-9 changed the risk of adverse events, establish that it did or did not improve clinical outcomes, or resolve the uncertainty around any between-group difference.

13. Why This Trial Matters Statistically

This trial is statistically notable because its primary outcome is a safety measure based on participant counts, while the study also includes a range of clinical and biomarker outcomes. That distinction matters: a record can list many outcomes without reporting results for each, and the primary safety counts cannot substitute for evidence about survival, respiratory support, or other clinical outcomes.

The study's two parts also require distinct interpretation. Part 1 was open-label and gave APL-9 to all participants, making it a safety-focused description without a concurrent control group. Part 2 was randomized and included a vehicle-control arm, providing a design for a comparative assessment. Combining the two parts as if they formed one randomized comparison would not reflect the design described in the registry record.

Group size and uncertainty matter when reading event counts. In general, counts from limited groups can be unstable, and a small numerical difference does not necessarily indicate a reliable treatment effect. The available registry information does not report confidence intervals or formal comparative tests for the primary safety figures, so the precision of any contrast cannot be established from these counts alone.

The record also illustrates why reporting methods matters. Interpretation depends on clear definitions, follow-up periods, analysis populations, missing-data handling, and plans for multiple outcomes. Some of these are described, including the TEAE definition and safety population, while a detailed analysis plan, multiplicity approach, and missing-data methods are not reported in the registry record. Statistical conclusions should be bounded by those reporting limits.

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 results available for interpretation are event counts by group. The registry record does not report confidence intervals, p-values, or a formal estimate comparing the randomized Part 2 arms. The precision of the counts and the uncertainty around any between-group difference therefore cannot be evaluated from the available results.

The primary outcome is safety-focused, and the registry record's listed secondary outcomes do not include reported results in the information available for this analysis. There is consequently no basis for interpreting clinical effectiveness from survival, hospital stay, SOFA score, oxygen therapy, mechanical ventilation, or biomarker outcomes.

Part 1 was open-label and had no control group described, so its counts cannot establish a comparative treatment effect. The record's masking descriptions also differ: it lists triple masking but describes Part 2 as double-blind and Part 1 as open-label. The record does not explain this wording or specify which roles were masked.

The percentages attached to serious-event terms are reported without a denominator or an explicit percentage basis in the available information. The record does not report missing-data handling, incomplete follow-up, exposure-time adjustment, or a detailed analysis plan for these results. It also does not report a sample-size justification or multiplicity approach. These omissions limit assessment of precision, potential bias, and the strength of any comparative conclusion; they do not establish that a particular bias occurred.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study of APL-9 in Adults With Mild to Moderate ARDS Due to COVID-19 — NCT04402060.
• Registry record last updated 2022-03-23; status last verified 2022-03.
• Results first posted 2022-03-23.
• 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

NCT04402060 is a completed randomized, parallel-group phase 1/phase 2 study of APL-9 in adults with mild to moderate ARDS due to COVID-19. Enrollment was 72. Part 1 was open-label and evaluated APL-9 with standard of care; Part 2 was described as randomized and compared APL-9 with vehicle control, each with standard of care. The record lists triple masking and also describes Part 2 as double-blind.

The primary outcome counted participants experiencing TEAEs and serious TEAEs during follow-up. Serious-event counts were 1 among 6 in Part 1: APL-9, 14 among 33 in Part 2: APL-9, and 15 among 32 in Part 2: Control. The registry record does not report formal comparative estimates or uncertainty measures for these counts in the available information. Results for the listed secondary outcomes, missing-data methods, multiplicity handling, and a detailed statistical analysis plan are not reported in the registry record.