This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Study to Evaluate the Safety and Efficacy of ATYR1923 (Efzofitimod) In Participants With Severe Pneumonia Related to COVID-19 (NCT04412668), a randomized phase 2 study. The primary outcome is Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04412668 |
| Phase | Phase 2 |
| Condition | SARS-CoV-2 (COVID-19) Severe Pneumonia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 36 |
| Arms in the primary outcome | n/a |
| Lead sponsor | aTyr Pharma, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
Adults hospitalized with severe pneumonia related to SARS-CoV-2 infection who did not require mechanical ventilation.
Intervention
A single intravenous infusion of efzofitimod at 1 mg/kg or 3 mg/kg on Day 1.
Comparator
A placebo infusion matched to efzofitimod, also given on Day 1.
Primary question
How many participants experienced treatment-emergent adverse events or serious adverse events from baseline up to Day 60?
The registry describes a randomized, double-blind, placebo-controlled study intended to evaluate safety and preliminary efficacy. The primary endpoint focuses on the number of participants with treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs), rather than on a single measure of recovery or disease progression. TEAEs were defined by onset after the first study-drug dose; SAEs were defined by specified serious outcomes or important medical events.
Recovery and hospital course were also addressed through secondary outcomes. These included time to hospital discharge, time to recovery defined by a World Health Organization (WHO) Ordinal Scale score of 3 or lower, recovery by Day 14 and Day 28, days with supplemental oxygen or fever, and changes in WHO score by Day 60. The registry lists these outcomes, but does not report inferential analyses for them. The clinical question is therefore best read as a safety question with additional planned descriptions of recovery-related outcomes, not as a reported test of whether efzofitimod improved recovery.
3. Trial Design
This was a Phase 2, randomized, parallel-group study with quadruple masking and a placebo control. It enrolled 36 participants. The registry describes adults with severe pneumonia related to SARS-CoV-2 infection; the brief summary specifies hospitalized participants who did not require mechanical ventilation. The study status is completed.
Participants were assigned to one of three groups: efzofitimod 1 mg/kg, efzofitimod 3 mg/kg, or placebo. Each group received a single intravenous infusion on Day 1. The placebo was matched to efzofitimod. Quadruple masking indicates that the registry classifies the study as masked across four roles, but the specific roles are not reported in the registry record.
The study started on 2020-06-04, and the primary completion date was 2020-10-23. The registry describes the primary safety observation period as baseline up to Day 60. Safety analyses used the Safety Set: randomized participants who received any amount of study drug. Participants were summarized and analyzed according to the treatment they actually received, rather than solely according to randomized assignment.
The registry lists several recovery and hospital-course outcomes in addition to the primary safety endpoint. It does not report a statistical analysis plan, a sample-size justification, or inferential results for those outcomes. Consequently, the design features can be described from the record, but the planned methods for estimating treatment differences cannot be reconstructed from it.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Efzofitimod 1 mg/kg | Efzofitimod 3 mg/kg | Placebo |
|---|---|---|---|
| STARTED | 14 | 12 | 10 |
| Received at Least 1 Dose of Study Drug | 10 | 12 | 10 |
| COMPLETED | 7 | 12 | 10 |
| NOT COMPLETED | 7 | 0 | 0 |
Reasons for not completing this period:
| Reason | Efzofitimod 1 mg/kg | Efzofitimod 3 mg/kg | Placebo |
|---|---|---|---|
| Death - multiple comorbidities | 2 | 0 | 0 |
| Withdrawal by Subject | 3 | 0 | 0 |
| Other than Specified | 2 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Safety Set was included all randomized participants who received any amount of study drug. Participants were summarized and analyzed 'as treated' (that is, by actual treatment group).
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: Safety Set was defined as all randomized participants who received any amount of study drug. Participants were summarized and analyzed 'as treated' (that is, by actual treatment group).
| Characteristic | Unit | Efzofitimod 1 mg/kg | Efzofitimod 3 mg/kg | Placebo | Total |
|---|---|---|---|---|---|
| Participants analysed | 10 | 12 | 10 | 32 | |
| Age, Continuous | years | 55.9 (SD 11.08) | 56.5 (SD 11.41) | 52.8 (SD 10.51) | 55.2 (SD 10.80) |
| Sex: Female, Male: Female | Participants | 5 | 6 | 3 | 14 |
| Sex: Female, Male: Male | Participants | 5 | 6 | 7 | 18 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 4 | 6 | 7 | 17 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 6 | 5 | 3 | 14 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 1 | 0 | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 1 | 0 | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 1 | 2 | 4 |
| Race (NIH/OMB): White | Participants | 6 | 4 | 3 | 13 |
| Race (NIH/OMB): More than one race | Participants | 2 | 5 | 3 | 10 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 1 | 2 | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs), measured over Baseline up to Day 60.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with TEAEs and SAEs from baseline up to Day 60. A TEAE is an adverse event that begins after the first dose of study drug. An adverse event is an untoward medical occurrence in a participant who received study drug and need not have a causal relationship with it. Worsening of a pre-existing condition was considered an adverse event if its severity, frequency, or duration increased, or if it was associated with significantly worse outcomes.
An SAE is an adverse event that, in the view of the Investigator or Sponsor, resulted in a fatal or life-threatening outcome, required hospitalization or prolonged an existing hospitalization, caused persistent or significant disability or incapacity, involved a congenital anomaly or birth defect, or was otherwise an important medical event.
Counting participants with an event is a useful safety summary because it describes how many people experienced at least one event during the specified period. It does not, by itself, describe how many separate events each person experienced, how long events lasted, or their severity beyond the SAE classification. The primary endpoint includes both TEAEs and SAEs, but the registry does not report a single combined comparison or an inferential analysis for that endpoint. The posted group counts should therefore be read as descriptive safety information, not as a quantified treatment effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted safety results report 10 participants at risk in the efzofitimod 1 mg/kg group, 12 in the 3 mg/kg group, and 10 in the placebo group. For SAEs, the corresponding numbers of participants with an event were 5, 0, and 0. For other, nonserious adverse events, the corresponding counts were 8, 7, and 7. The reported death counts were 2, 0, and 0, respectively. These are descriptive counts in the Safety Set, analyzed according to actual treatment received.
The SAE counts show that serious events were reported in the 1 mg/kg group and were not reported in the other groups. The record does not establish why those events occurred or whether they were caused by study treatment. The adverse-event definition explicitly does not require a causal relationship, and the endpoint description states that the displayed summaries include events regardless of causality. The death counts likewise should not be interpreted as evidence of treatment causation on their own.
The registry lists six serious-event terms, each reported as 10.0%: acute respiratory distress syndrome, hypoxia, pneumomediastinum, pneumonitis, pulmonary embolism, and respiratory failure. These term-level percentages do not replace the participant-level group counts, and the record does not provide enough detail to determine whether any participant experienced more than one listed event. Each term should be read as a reported adverse-event category, not as a causal attribution.
No inferential analysis is reported for the primary endpoint. The registry record therefore does not provide a treatment-effect estimate, confidence interval, or p-value for a comparison of the groups. It also does not provide a single combined primary-endpoint result that could be interpreted as a direct contrast of TEAEs and SAEs. The counts describe what was recorded among the participants included in the safety analysis; they do not quantify the precision of a treatment difference.
The study enrolled 36 participants across three groups, so the safety findings are based on a small study population. In general, small groups can yield unstable estimates, particularly for uncommon events. That general limitation is relevant to interpreting the observed counts, but it does not supply a missing inferential analysis. The registry does not report enough information to determine whether the group counts differ beyond what could plausibly arise from sampling variation.
The listed secondary outcomes cover discharge, recovery, oxygen use, fever, and WHO score. Their inclusion indicates what the study tracked, but outcome names alone are not results. Because inferential analyses are not reported in the registry record, no conclusion about a comparative recovery effect can be drawn from these listings. The safety counts are the available group-level results; they should not be extended into claims about efficacy or causation.
9. Statistical Methods Explained
What kind of endpoint is this? The primary endpoint counts participants who experienced adverse events, rather than measuring a continuous quantity such as a laboratory value. For each participant, the relevant classification is whether an event meeting the endpoint definition occurred during the stated observation period. This is a participant-level event count, not a count of every event episode. The posted results separately report SAE counts, other adverse-event counts, and deaths.
General: how to read group counts. A count should be read alongside the number of participants at risk in that group. The record reports both values for each treatment group. These summaries describe the observed Safety Set. They do not automatically provide a comparison adjusted for baseline characteristics, and no such adjustment is reported in the registry record. The groups also reflect actual treatment received for safety summarization, as specified in the record.
General: uncertainty and confidence intervals. A confidence interval is a range of values compatible with the data under a statistical model and a stated confidence procedure. Its width communicates precision: wider intervals indicate less precise estimates. For event counts, uncertainty can be substantial when groups are small or events are uncommon. A confidence interval for a difference or ratio would require a defined comparison and a specified method. No such estimate or interval for the primary endpoint is reported in the registry record, so the precision of a comparative safety effect cannot be assessed from the reported counts alone.
General: why a p-value is not enough. A p-value, when calculated under a specified model, describes how compatible the observed data are with a null hypothesis. It does not measure the probability that a treatment works, nor does it describe the size or clinical importance of an effect. A p-value is not reported for the primary endpoint. In its absence, the counts should remain descriptive; a reader should not infer statistical significance from which groups have nonzero counts.
General: event counts and over-dispersion. Over-dispersion occurs when event data vary more than a chosen statistical model expects. It can matter when analyzing numbers of events, particularly if some participants experience repeated events while others experience none. The primary endpoint is framed as the number of participants with events, which is distinct from the total number of event episodes. The registry does not provide repeated-event analysis or information about event recurrence, so over-dispersion cannot be assessed from these participant counts.
How to interpret the sample-size planning assumptions. The record describes planning illustrations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that the effect to detect is expressed as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial was designed with those assumptions or that a particular power was achieved. Any sample-size illustration is a planning quantity, not observed power. A trial-specific sample-size justification is not reported in the registry record. The study itself has three treatment groups, while the stated illustration assumes equal allocation between two arms; the illustration should not be mistaken for the actual trial allocation.
Why the endpoint does not yield a single comparison. The registry identifies the primary outcome as having several categories or time points and does not reduce it to one comparison. This matters because an analysis requires a defined estimand and contrast: for example, which groups are compared, which event definition is used, and how event timing is handled. The registry does not report that specification or the statistical procedure. No inferential analysis is listed, so the appropriate interpretation is a descriptive one based on the posted counts and event definitions, rather than a reconstructed test.
General: randomized design and analysis population. Randomization is intended to create comparable groups at assignment, subject to chance variation. The safety analysis population in this record is not simply described as everyone randomized: it includes randomized participants who received any amount of study drug, and participants are summarized by actual treatment. That definition is relevant when reading the denominators. The registry does not report a separate efficacy analysis population or an intention-to-treat analysis for recovery outcomes.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists multiple secondary outcomes: time to hospital discharge, time to recovery using a WHO Ordinal Scale score of 3 or lower, recovery by Day 14 and Day 28, days with supplemental oxygen, days with fever, change in WHO score on Day 60, and time to improvement by at least one point on the WHO scale. Several outcomes involve more than one time point or measure. Testing many outcomes can increase the chance of at least one apparently unusual result if each is assessed separately. General statistical approaches to this issue include defining a hierarchy of outcomes or adjusting the testing procedure, but the registry record does not report whether either approach was planned or used.
Missing-data handling is not reported in the registry record. The record does not describe how participants with incomplete follow-up, missing outcome measurements, or early withdrawal were handled for the primary or secondary outcomes. It also does not state whether any imputation method was planned. Without those details, the influence of incomplete observations on the reported results cannot be assessed.
The registry identifies the Safety Set as randomized participants who received any amount of study drug, analyzed according to actual treatment. It does not report an efficacy analysis population or the analysis population used for each listed recovery outcome. The record also does not report interim analyses, stopping rules, a statistical analysis plan, or a sample-size justification. No inferential analyses are listed. These omissions limit assessment of multiplicity control, missing-data assumptions, and the prespecification of analyses; they do not demonstrate that a particular method was or was not used outside the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Efzofitimod 1 mg/kg | 5 | 10 | 50.0% |
| Efzofitimod 3 mg/kg | 0 | 12 | 0.0% |
| Placebo | 0 | 10 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Efzofitimod 1 mg/kg | 2 of 10 |
| Efzofitimod 3 mg/kg | 0 of 12 |
| Placebo | 0 of 10 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Efzofitimod 1 mg/kg | 8 of 10 |
| Efzofitimod 3 mg/kg | 7 of 12 |
| Placebo | 7 of 10 |
Most frequent serious adverse event terms
| Event term | Organ system | Efzofitimod 1 mg/kg | Efzofitimod 3 mg/kg | Placebo |
|---|---|---|---|---|
| Acute respiratory distress syndrome | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Hypoxia | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Pneumomediastinum | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Pneumonitis | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Pulmonary embolism | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Respiratory failure | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Septic shock | Infections and infestations | 1 of 10 | 0 of 12 | 0 of 10 |
| Urosepsis | Infections and infestations | 1 of 10 | 0 of 12 | 0 of 10 |
| Acute myocardial infarction | Cardiac disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Hypotension | Vascular disorders | 1 of 10 | 0 of 12 | 0 of 10 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Efzofitimod 1 mg/kg | Efzofitimod 3 mg/kg | Placebo |
|---|---|---|---|---|
| Tachycardia | Cardiac disorders | 2 of 10 | 0 of 12 | 0 of 10 |
| Blood urea increased | Investigations | 1 of 10 | 1 of 12 | 0 of 10 |
| Platelet count increased | Investigations | 0 of 10 | 1 of 12 | 1 of 10 |
| Pruritus | Skin and subcutaneous tissue disorders | 1 of 10 | 0 of 12 | 1 of 10 |
| Pneumomediastinum | Respiratory, thoracic and mediastinal disorders | 0 of 10 | 1 of 12 | 0 of 10 |
| Dyspnoea exertional | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Epistaxis | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Nasal dryness | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Oropharyngeal pain | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
| Pneumothorax | Respiratory, thoracic and mediastinal disorders | 1 of 10 | 0 of 12 | 0 of 10 |
Serious events with the highest arm-level rate: acute respiratory distress syndrome (10.0%), hypoxia (10.0%), pneumomediastinum (10.0%), pneumonitis (10.0%), pulmonary embolism (10.0%).
The safety figures give, for each group, the number of participants at risk and the number with serious or other adverse events. SAEs were reported for 5 of 10 participants in the efzofitimod 1 mg/kg group, 0 of 12 in the 3 mg/kg group, and 0 of 10 in the placebo group. Other, nonserious adverse events were reported for 8 of 10, 7 of 12, and 7 of 10 participants, respectively. Deaths were reported for 2 participants in the 1 mg/kg group and none in the other groups.
These counts are not, by themselves, estimates of treatment causation. The registry defines adverse events without requiring a causal relationship to study drug, and the SAE summary includes events regardless of causality. The listed serious-event terms—acute respiratory distress syndrome, hypoxia, pneumomediastinum, pneumonitis, pulmonary embolism, and respiratory failure—are each reported as 10.0%. The record does not establish that these events were caused by treatment or explain their relationship to individual participant outcomes. Because the groups are small and no comparative inference is reported, the counts should be read as descriptive observations, not as definitive evidence of a difference between treatments.
12. What the Result Does, and Does Not, Mean
The registry record supports a description of the study design and the safety events reported among participants who received study drug. The study compared two efzofitimod dose groups with placebo in a randomized, masked, parallel-group design. Its primary endpoint concerned participants with TEAEs and SAEs through Day 60. The record also reports group-level counts for serious events, other adverse events, and deaths.
Those counts do not establish that an event was caused by treatment. They also do not establish that a group difference is statistically reliable. The registry does not report a treatment-effect estimate, confidence interval, or p-value for the primary endpoint, and it does not reduce the endpoint to a single comparison. The record therefore does not quantify how precisely the observed group counts estimate a difference in underlying risk.
The registry’s secondary-outcome list describes recovery and hospital-course measures, but a list of planned outcomes is not evidence of an observed treatment effect. Inferential analyses for those outcomes are not reported in the registry record. The counts cannot be used to claim that efzofitimod improved recovery, shortened hospitalization, changed oxygen use, or altered fever or WHO scores.
More generally, the results should be interpreted within the study’s size and analysis population. There were 36 enrolled participants, and the safety summaries include randomized participants who received any amount of study drug, classified by actual treatment. Small group counts can leave considerable uncertainty, especially for uncommon events; no comparative precision measure is reported. The study record is informative about what was recorded, but it does not support a definitive efficacy conclusion or a causal explanation for individual safety events.
13. Why This Trial Matters Statistically
This trial illustrates why a randomized design and a reported analysis are both needed for statistical interpretation. Randomization provides a framework for comparing treatment groups, but the reader still needs a clearly specified outcome contrast and an analysis that estimates the difference with its uncertainty. Here, the primary endpoint is described as a count of participants with TEAEs and SAEs, yet the registry does not report a single comparison or inferential result for that endpoint.
The record also illustrates the distinction between event classification and causality. TEAEs are defined by their timing after the first dose, while adverse events need not be caused by study drug. SAEs meet severity or consequence criteria, but those criteria do not establish attribution. Reading safety counts as causal effects would go beyond what these definitions and results support.
Finally, the registry lists several secondary measures of recovery and hospital course alongside the safety endpoint. Multiple outcomes can raise questions about which comparisons were primary, how multiplicity was handled, and how missing observations were treated. Those details are not reported in the registry record. This makes the trial a useful example of the limits of interpreting an outcome list and descriptive counts when the corresponding statistical plan and inferential analyses are unavailable.
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 registry record does not report a statistical analysis plan, a trial-specific sample-size justification, or inferential analyses for the primary endpoint. It also does not report a treatment-effect estimate, confidence interval, or p-value. Consequently, comparative effects and their precision cannot be evaluated from the posted results.
The primary outcome is described using TEAEs and SAEs, but the registry indicates that it has several categories or time points and is not reduced to one comparison. The available counts separate serious from other adverse events and list deaths, but do not provide a single combined primary-endpoint result. The record does not report whether individuals could contribute to multiple event categories, how repeated events were handled, or how event timing was analyzed.
The registry does not report the handling of missing data, withdrawal, or incomplete follow-up. It does not state whether interim analyses or stopping rules were used, or how multiplicity across secondary outcomes was addressed. Although recovery and hospital-course outcomes are listed, their analyses and results are not reported.
The safety population includes randomized participants who received any amount of study drug and classifies them by actual treatment. A separate analysis population for efficacy outcomes is not reported. The study enrolled 36 participants, with group counts that are limited for assessing uncommon events. These limitations constrain precision and interpretation; they do not reveal what unreported analyses may have been conducted outside the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study to Evaluate the Safety and Efficacy of ATYR1923 (Efzofitimod) In Participants With Severe Pneumonia Related to COVID-19 — NCT04412668.
- Registry record last updated 2023-08-18; status last verified 2023-07.
- Results first posted 2023-08-18.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT04412668 is a completed Phase 2 randomized, quadruple-masked, parallel-group study of efzofitimod for adults hospitalized with severe pneumonia related to SARS-CoV-2 infection who did not require mechanical ventilation. The registry reports 36 enrolled participants assigned to efzofitimod 1 mg/kg, efzofitimod 3 mg/kg, or matched placebo as a single intravenous infusion on Day 1.
The primary endpoint counted participants with TEAEs and SAEs from baseline up to Day 60. Safety summaries were based on randomized participants who received any study drug and were analyzed according to actual treatment. The registry reports group counts for SAEs, other adverse events, and deaths, as well as several secondary recovery and hospital-course outcomes.
No inferential analyses are reported in the registry record. A sample-size justification, missing-data approach, multiplicity method, and statistical analysis plan are also not reported. The posted counts support descriptive safety interpretation, but do not quantify a comparative treatment effect or establish causality.