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 Efficacy and Safety of APD334 in Patients With Pyoderma Gangrenosum (NCT03072953), a na phase 2 study. The primary outcome is Exploratory Endpoint - Change From Baseline in Physician Global Assessments for Active Skin Manifestations.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03072953 |
| Phase | Phase 2 |
| Condition | Pyoderma Gangrenosum |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 2 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Arena Pharmaceuticals |
| Results posted | Yes |
2. Clinical Question
Population
Patients with pyoderma gangrenosum. The registry record reports enrollment of 2 participants. It does not give further participant characteristics.
Intervention
APD334, also identified as etrasimod, active treatment for 12 weeks.
Comparator
There was no comparator group. The study is recorded as single-group, with allocation listed as NA and masking listed as none.
Primary question
The exploratory primary endpoint concerned change from baseline in physician global assessments for active skin manifestations at Week 12. The assessment recorded ulcer number, a target lesion for endpoint evaluation, target-lesion diameters, and an evaluation score.
The clinical question was whether physician assessments of active skin manifestations changed during treatment in this small, open-label proof-of-concept study. The endpoint’s score ranged from 0, meaning total resolution, to 4, meaning no evidence of healing. Those anchors describe the scale; they do not indicate the scores observed in the participants.
The record does not include a like-for-like control comparison. Therefore, even if participant-level changes had been reported, changes during treatment could not by themselves separate treatment-associated change from the range of change that might occur without treatment. In this record, efficacy analyses were not conducted because enrollment was low, and the results from the enrolled participants cannot be reported for privacy reasons. The primary clinical question consequently remains unanswered by the posted efficacy results.
3. Trial Design
This was a phase 2a, open-label, proof-of-concept study of etrasimod, identified in the record as APD334, in patients with pyoderma gangrenosum. The intervention was active APD334 treatment for 12 weeks. The recorded study model was single-group, allocation was NA, and masking was none. Enrollment was 2.
The registry record lists the study status as terminated. The study start date was 2017-06-07, and the primary completion date was 2018-05-22. Arena Pharmaceuticals is listed as the sponsor. The record does not state why the study was terminated, so the reason should not be inferred from the status alone.
A single-group design describes participants receiving the intervention without a concurrent comparator group. Open-label means that the study was not masked. General statistical context: without random allocation to a control group, comparisons with an untreated or alternative-treatment group are not available within the study. An observed change over time, if reported, would describe the enrolled participants, but would not by itself establish what would have happened to comparable participants without the intervention.
The registry record lists 7 outcome measures. It identifies the physician global assessment endpoint as exploratory and specifies Week 12 as its timeframe. The listed endpoint description includes assessments recorded at each visit, but the record does not give a schedule of visits beyond the endpoint timeframe. Other details about the protocol, such as eligibility criteria, dose, adherence, visit timing, and the reason for termination, are not reported in the registry record.
The enrollment of 2 is especially important to interpreting the record. The registry explicitly states that efficacy analyses were not conducted because enrollment was low and that results from participants cannot be reported to protect privacy. Thus, the design information is available, but a numerical estimate of change on the primary endpoint is not reported. The record also lists 0 analyses. No explanation of the enrollment target or sample-size justification is reported in the registry record.
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 | APD334 |
|---|---|
| STARTED | 2 |
| COMPLETED | 2 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Efficacy analyses were not conducted due to low enrollment (N=2). In order to protect participant's privacy, the results from the enrolled participants cannot be reported.
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.
| Characteristic | Unit | APD334 |
|---|---|---|
| Participants analysed | 2 | |
| Age, Customized: Between 18 to 80 years | Participants | 2 |
| Sex: Female, Male: Female | Participants | NA |
| Sex: Female, Male: Male | Participants | NA |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | NA |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | NA |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | NA |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 2 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Exploratory Endpoint - Change From Baseline in Physician Global Assessments for Active Skin Manifestations, measured over Week 12.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The exploratory primary endpoint was change from baseline in physician global assessments for active skin manifestations, with Week 12 specified as the endpoint timeframe. The physician assessment recorded the number of ulcers, a target lesion identified for endpoint evaluation, the diameters of each target lesion, and an evaluation score at each visit. The score ranged from 0, defined as total resolution, to 4, defined as no evidence of healing.
In general, a physician global assessment can bring several clinical observations into an overall evaluation. A scale with stated anchors gives the reader a way to understand what low and high scores represent. Here, the endpoint description identifies both lesion-related observations and the meaning of the score endpoints. The registry does not specify in this record how the individual observations were combined, whether scores were analyzed as numeric or categorical data, or what amount of change would be considered clinically important. Those details are not reported in the registry record.
Change from baseline is often used to describe how an assessment differs from a participant’s starting value. General statistical context: comparing changes can be informative when baseline and follow-up measurements are available, but the interpretation depends on the design, the measurement scale, and the analysis plan. No baseline or Week 12 participant values, group summary, or change estimate is reported. The registry states that efficacy analyses were not conducted and that results from enrolled participants cannot be reported to protect privacy. The endpoint definition therefore explains what was intended to be assessed, not what happened to the participants.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The main statistical feature of this record is not an estimated treatment effect but the absence of reportable efficacy results. Although the study identifies a Week 12 exploratory primary endpoint and describes its physician assessment scale, the registry states that efficacy analyses were not conducted because enrollment was low. It also states that the enrolled participants’ results cannot be reported to protect privacy. No participant-level values, group summary, change estimate, confidence interval, or efficacy test result is reported in the registry record.
Consequently, the direction and size of any change in physician global assessments cannot be established from the posted results. The score anchors alone do not reveal whether scores improved, worsened, or stayed the same. Nor does the endpoint description show how consistent any participant changes may have been. With no reported estimate or uncertainty interval, the precision of an efficacy estimate cannot be assessed.
The design further limits causal interpretation. The study was single-group and open-label, with no comparator; allocation is listed as NA and masking as none. General statistical context: a before-and-after description in one group does not provide the counterfactual comparison needed to distinguish an intervention-associated change from other influences or the course of the condition over time. In this record, even a before-and-after description is not available because the efficacy results were withheld and analyses were not conducted.
The enrollment of 2 also means that the study record contains very little information about the range of responses among participants. The privacy statement explains why individual results cannot be reported; it does not permit a reader to reconstruct outcomes or infer a group average. The registry does not report a reason for the termination, so termination should not be treated as evidence about efficacy or safety.
The posted safety counts are a separate part of the record and should not be mistaken for an efficacy analysis. Two participants were at risk for serious adverse events, 0 were reported as affected, and deaths were 0. For other adverse events, 2 were at risk and 2 were reported as affected. These counts describe the recorded safety categories in a very small study; they do not supply details about event type, timing, severity beyond the serious-event category, or relationship to treatment.
Overall, the record establishes that a small, open-label proof-of-concept study was conducted and terminated, and that safety-category counts were posted. It does not establish a numerical effect on the primary endpoint. No conclusion about the treatment’s efficacy can be drawn from an endpoint definition without results. Similarly, zero recorded serious adverse events among 2 at-risk participants is not evidence that serious events cannot occur. The estimates needed to assess either efficacy or the precision of safety experience are not reported in the registry record.
9. Statistical Methods Explained
The methods information must be separated into what the registry records and what can be explained only as general statistical context. The record identifies a phase 2a, open-label, single-group study, enrollment of 2, a 12-week active treatment period, and an exploratory physician global assessment endpoint at Week 12. It says efficacy analyses were not conducted because of low enrollment. The analysis methods actually used for efficacy are therefore not described as a completed analysis, and details of an inferential statistical plan are not reported in the registry record.
What a single-group design can describe
General statistical context: a single-group study can describe outcomes among participants who receive an intervention. If baseline and follow-up measurements are collected and reported, their changes can be summarized. However, without a concurrent comparison group, those observations do not isolate the effect of the intervention from changes that may arise over time or from other influences. This is why a within-group change and a controlled treatment contrast answer different questions. The present registry record reports no efficacy values with which to describe even the within-group changes.
Open-label status means masking was none, as recorded. General statistical context: knowledge of treatment assignment can influence subjective assessments or reporting, depending on the outcome and study procedures. A physician global assessment includes a clinician’s evaluation, so masking could be relevant when considering the possibility of assessment influence. The registry does not describe safeguards, assessor arrangements, or procedures for reducing such influence; those details are not reported in the registry record.
What the endpoint scale tells the reader
The physician assessment score is described as ranging from 0, total resolution, to 4, no evidence of healing. General statistical context: a scale with ordered categories can convey rank or severity, but the numerical spacing between adjacent categories is not necessarily equal unless the scale and analysis support that interpretation. The record does not state how the score was treated statistically, how ulcer number and lesion diameters entered any analysis, or whether a composite score was calculated. Such endpoint-analysis details are not reported in the registry record.
Change from baseline generally means comparing a follow-up measurement with a starting measurement for the same participant. A group-level summary of change can describe the average or distribution of changes, depending on the method. To judge the uncertainty of such a summary, readers would usually need the observations or appropriate summary statistics and an analysis approach. None of those efficacy results is reported. There is therefore no basis for reconstructing a change estimate or its uncertainty.
Estimates, uncertainty, and tests
General statistical context: an estimate is a numerical summary of the effect or outcome being studied. A confidence interval gives a range of values compatible with the data under the assumptions of the method; it communicates uncertainty rather than guaranteeing that a particular value is correct. A significance test evaluates data against a specified null hypothesis under an analysis plan. The registry record reports no efficacy estimate, confidence interval, or p-value. It also does not report the inferential model, test, handling of the score scale, or a pre-specified threshold for interpreting change.
These methods should not be retroactively assigned to the study. The fact that a method could be used for this kind of endpoint does not show that it was planned or conducted. The registry record does not report an efficacy analysis because it explicitly states that such analyses were not conducted. Any method-specific efficacy interpretation would therefore go beyond the posted record.
Planning illustrations are not study results
The record describes a planning illustration computed from an observed effect, not from the trial’s own design. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. It also distinguishes total events for time-to-event illustrations from participants per arm for other illustrations. These are planning assumptions, not a description of the single-group study, which has no comparator arm.
General statistical context: a planning calculation estimates the sample size that might be needed under specified assumptions. It is not a report of how many participants were enrolled, and it is not observed power. Because no observed efficacy estimate is reported in the registry record, readers should not treat a planning illustration based on an observed effect as evidence of an effect in this study. The actual sample-size justification and any assumptions used when designing the trial are not reported in the registry record.
In general, over-dispersion means that data vary more than a chosen statistical model expects. If relevant, ignoring it can make uncertainty estimates too narrow. The registry record does not report whether over-dispersion was assessed or relevant to any analysis, and no efficacy analysis was conducted. It would therefore be inappropriate to claim that this issue affected the study’s results. More broadly, no statistical model, adjustment method, or analysis-population definition for efficacy is reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 7 outcome measures and identifies the physician global assessment for active skin manifestations as an exploratory primary endpoint. It does not report a testing hierarchy, a multiplicity adjustment, or how conclusions were to be drawn across the outcome measures. These details are not reported in the registry record. General statistical context: when several outcomes or repeated tests are examined, the chance of at least one apparently notable result can increase unless the analysis plan accounts for the testing structure. That general concern cannot be resolved by assuming an unreported adjustment.
Missing-data methods and analysis populations are also not described. The record states that efficacy analyses were not conducted because enrollment was low, and that results from the enrolled participants cannot be reported to protect privacy. It does not provide participant-level outcome availability, reasons for missing measurements, a definition of an efficacy analysis set, or a method for handling missing values. Those items are not reported in the registry record. Because there are no reportable efficacy analyses, no missing-data procedure can be evaluated from the posted results.
The record lists 0 analyses. That is consistent with the statement that efficacy analyses were not conducted, but it does not establish what analysis methods might have been planned before the study began. The protocol’s statistical analysis plan, any interim analyses, and sample-size justification are not reported in the registry record. The record’s separate planning illustration assumptions do not fill those gaps: they describe a planning calculation, not a multiplicity strategy, missing-data method, or analysis population for this single-group trial.
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 |
|---|---|---|---|
| APD334 | 0 | 2 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| APD334 | 0 of 2 |
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 |
|---|---|
| APD334 | 2 of 2 |
Most frequent non-serious adverse event terms
| Event term | Organ system | APD334 |
|---|---|---|
| Diarrhea | Gastrointestinal disorders | 1 of 2 |
| headache | Nervous system disorders | 1 of 2 |
| Pruritus | Skin and subcutaneous tissue disorders | 1 of 2 |
| Sore hip | Injury, poisoning and procedural complications | 1 of 2 |
For APD334, the registry reports 2 participants at risk for serious adverse events and 0 affected. The recorded death count is 0. For other adverse events, 2 participants were at risk and 2 were affected. No serious adverse event terms are listed. These counts are the safety figures reported in the registry record.
General statistical context: a count of affected participants is not the same as a complete description of the events. The posted figures do not specify the nature, timing, duration, severity of the other adverse events, or whether any event was considered related to treatment. The record also does not provide further detail about how events were defined or collected. Such details are not reported in the registry record.
The denominator is small: 2 participants were at risk in each posted category. A count of 0 serious adverse events in this study does not establish that the risk is absent; it means none were recorded among the participants at risk in this record. Likewise, the other-adverse-event count does not establish a rate that can be generalized to a broader population. These safety figures should be read as a limited description of the enrolled participants, not as a precise estimate of the frequency or range of potential events.
12. What the Result Does, and Does Not, Mean
The record documents a phase 2a, open-label, single-group proof-of-concept study of APD334, also named etrasimod, in patients with pyoderma gangrenosum. The active treatment period is listed as 12 weeks, and the exploratory primary endpoint was a physician global assessment of active skin manifestations at Week 12. Enrollment was 2, and the study status is terminated.
What the record does not provide is a numerical result for that primary endpoint. It explicitly states that efficacy analyses were not conducted because enrollment was low and that results from enrolled participants cannot be reported to protect privacy. Therefore, the posted information cannot show the direction, magnitude, or consistency of changes in the physician assessments. It also cannot show how precisely any treatment effect was estimated, because no such estimate or confidence interval is reported.
The study design does not include a comparator group. General statistical context: observing change within a treated group is not equivalent to estimating a treatment effect against a control group. In this record, there is no reportable efficacy summary to interpret in either way. The absence of an efficacy result should not be recast as evidence of benefit, lack of benefit, or no change.
The safety counts are also limited in scope. The record reports 0 serious adverse events among 2 at-risk participants and 0 deaths, as well as other adverse events affecting 2 of 2 participants at risk. These counts do not describe event types or provide a precise estimate of safety in a larger population. The reason for termination and the study’s sample-size justification are not reported in the registry record, so neither should be inferred from the status or enrollment.
In short, the registry record provides design information, an endpoint definition, and small-sample safety counts, but it does not provide reportable efficacy results. The clinical question about change in physician-assessed skin manifestations remains unresolved by the posted results. These limitations are about what can be concluded from this record; they are not a recommendation about treatment or care.
13. Why This Trial Matters Statistically
This study illustrates how an endpoint can be clearly defined while still yielding no interpretable efficacy estimate in the registry record. The physician assessment is described in terms of ulcer number, a target lesion, lesion diameters, and a score with defined anchors. Yet enrollment was 2, and the record says efficacy analyses were not conducted and participant results could not be reported to protect privacy. Endpoint detail cannot substitute for outcome data.
It also highlights the distinction between a study design and a statistical comparison. This was an open-label, single-group study with no comparator. General statistical context: a single-group design can support description of observed outcomes when those outcomes are reported, but it cannot supply a randomized contrast. In this case, the lack of a comparator and the lack of reportable efficacy results both limit what can be learned about change attributable to the intervention.
The record further shows why safety counts must be read in light of their denominators and detail. The serious adverse event count is 0 among 2 at risk, while other adverse events affected 2 of 2 at risk. These are useful descriptions of what the registry records, but the small enrollment and lack of event details preclude precise characterization of safety experience.
Finally, planning calculations should be kept separate from trial findings. The record describes planning assumptions for illustrations, while the study itself was single-group and had enrollment of 2. A planning estimate is not an observed effect and is not observed power. This distinction matters whenever a hypothetical sample-size calculation appears alongside a study with no reportable efficacy analysis. The statistical contribution of the record is therefore chiefly methodological: it makes clear which design and endpoint details are known and which conclusions remain unsupported by posted results.
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.
Several limitations specific to this study constrain interpretation. Enrollment was 2, and the registry states that efficacy analyses were not conducted because of low enrollment. It further states that results from the enrolled participants cannot be reported to protect privacy. No participant-level outcomes or group efficacy summaries are available in the registry record, so the primary endpoint cannot be assessed from the posted results.
The study was open-label and single-group, with no comparator. This means there is no concurrent control contrast in the design. Even if a change estimate were reported, a single-group change would not by itself distinguish an intervention-associated effect from other explanations. Here, no efficacy change estimate is reported at all.
The primary endpoint is identified as exploratory. The record describes its components and score anchors but does not report how those elements were combined or statistically analyzed. It does not specify the amount of change considered important, provide an analysis plan, or report uncertainty around outcomes. These details are not reported in the registry record.
There are also important gaps in the trial description. The reason for termination, sample-size justification, analysis populations, handling of missing data, multiplicity approach, and interim analyses are not reported in the registry record. The record lists 7 outcome measures, but does not state how findings across them were to be interpreted. The safety summaries give counts but do not describe the types or timing of other adverse events.
These limitations do not establish why the study ended or what the unreported participant outcomes were. They define the boundary of what can be concluded from the registry record: the design and endpoint are described, but efficacy results are not reportable and the safety experience is based on very few participants.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy and Safety of APD334 in Patients With Pyoderma Gangrenosum — NCT03072953.
- Registry record last updated 2021-06-11; status last verified 2021-05.
- Results first posted 2021-06-11.
- 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
NCT03072953 is a phase 2a, open-label, single-group proof-of-concept study of etrasimod (APD334) in patients with pyoderma gangrenosum. Arena Pharmaceuticals is listed as sponsor. The record gives a study start date of 2017-06-07, a primary completion date of 2018-05-22, and status of terminated. Active treatment was listed for 12 weeks, and enrollment was 2.
The exploratory primary endpoint was change from baseline in physician global assessments for active skin manifestations at Week 12. Its score ranged from 0, total resolution, to 4, no evidence of healing. Efficacy analyses were not conducted because enrollment was low, and participant results cannot be reported to protect privacy.
Safety figures list 0 serious adverse events among 2 at risk, 0 deaths, and other adverse events affecting 2 of 2 at risk. The record does not report the reason for termination, an efficacy estimate, or the statistical analysis details needed to evaluate treatment effects.