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 Etrasimod (APD334) in Inflammatory Bowel Disease Patients With Active Skin Extra-intestinal Manifestations (NCT03139032), a na phase 2 study. The primary outcome is Exploratory Endpoint - Change From Baseline in Endoscopic Improvement/Histologic Healing Using Endoscopy or Flexible Proctosigmoidoscopy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03139032 |
| Phase | Phase 2 |
| Condition | Inflammatory Bowel Diseases, Skin Extra-intestinal Manifestations |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Arena Pharmaceuticals |
| Results posted | Yes |
2. Clinical Question
Population
People with inflammatory bowel disease and active skin extra-intestinal manifestations were the intended study population. The registry record reports enrollment of 1, but does not report further participant characteristics.
Intervention
Participants received APD334, identified in the trial title and summary as etrasimod. The treatment arm description specifies active treatment for 12 weeks.
Comparator
There was no separate comparator group: the study is described as single-group, with allocation listed as not applicable. It was open-label, with masking listed as none.
Primary question
The exploratory primary endpoint concerned change from baseline in endoscopic improvement or histologic healing, assessed using endoscopy or flexible proctosigmoidoscopy. A further evaluation at week 12 was planned only if signs of inflammation were present at screening. Efficacy analyses were not conducted because enrollment was low (N=1), and the single participant’s results cannot be reported to protect privacy.
3. Trial Design
NCT03139032 was a phase 2a, proof-of-concept, open-label study sponsored by Arena Pharmaceuticals. Its stated purpose was to evaluate the efficacy and safety of etrasimod (APD334) in inflammatory bowel disease patients with active skin extra-intestinal manifestations. The study had a single group receiving APD334 active treatment for 12 weeks. Allocation was listed as not applicable, and masking was listed as none; the registry record therefore describes no randomized assignment or blinded comparison.
The record reports enrollment of 1. The study began on 2017-07-17, had a primary completion date of 2017-12-06, and is listed as terminated. The reason for termination is not reported in the registry record. The record identifies 17 outcome measures and 0 analyses, but efficacy analyses were not conducted because of low enrollment. The results for the single participant cannot be reported to protect privacy.
The primary endpoint was exploratory and concerned change from baseline in endoscopic improvement or histologic healing, using endoscopy or flexible proctosigmoidoscopy. The description says another evaluation was planned at week 12 only if signs of inflammation were present at screening. The record does not report whether that condition was met or whether the planned evaluation took place. Further details of eligibility criteria, treatment administration, adherence, and the statistical analysis plan are not reported in the registry record.
Because there was no control group, the study design could describe observations during treatment but could not make a randomized comparison with an untreated or alternative-treatment group. Open-label conduct also means that masking was not used. These design features are important context when considering the stated purpose and the absence of reportable efficacy results.
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 | Etrasimod |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Efficacy analyses were not conducted due to low enrollment (N=1). In order to protect participant's privacy, the results from a single participant 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 | Etrasimod |
|---|---|---|
| Participants analysed | 1 | |
| Age, Customized: Between 18 to 80 years | Participants | 1 |
| 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 | NA |
| Race (NIH/OMB): Asian | Participants | NA |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | NA |
| Race (NIH/OMB): Black or African American | Participants | NA |
| Race (NIH/OMB): White | Participants | NA |
| Race (NIH/OMB): More than one race | Participants | NA |
| Race (NIH/OMB): Unknown or Not Reported | Participants | NA |
6. Primary Endpoint
The registry lists the primary outcome as Exploratory Endpoint - Change From Baseline in Endoscopic Improvement/Histologic Healing Using Endoscopy or Flexible Proctosigmoidoscopy, measured over Weeks 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 primary endpoint was an exploratory measure of change from baseline in endoscopic improvement or histologic healing. Assessment was to use endoscopy or flexible proctosigmoidoscopy. The registry record specifies a week 12 timeframe, with a further evaluation planned only if signs of inflammation were present at screening.
In general, endoscopic assessment allows investigators to examine visible features of the bowel lining, while histologic assessment concerns tissue findings. Change from baseline is intended to describe how an assessment differs from its starting measurement. Such measures can capture features of disease activity that may not be fully represented by symptoms alone. The registry record does not provide the scoring system, thresholds for improvement or healing, details of tissue assessment, or a rule for combining endoscopic and histologic findings.
The endpoint is exploratory, and the registry record reports that efficacy analyses were not conducted because enrollment was low (N=1). To protect the participant’s privacy, the result cannot be reported. Consequently, no baseline value, follow-up value, change estimate, or uncertainty estimate for the endpoint is available in the registry record. The endpoint’s intended measurement role can be described, but its observed value and any evidence of change cannot be assessed from the record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that this study does not provide a reportable efficacy estimate. Although the registry identifies an exploratory primary endpoint and a planned week 12 assessment under a stated screening condition, efficacy analyses were not conducted because enrollment was low (N=1). The result for the single participant cannot be reported to protect privacy. Accordingly, there is no reported estimate of change from baseline in endoscopic improvement or histologic healing to interpret.
This is different from a study that reports an estimate with a wide confidence interval. A wide interval would still communicate a range of values compatible with the observed data under the analysis assumptions. Here, the registry record does not provide the participant-level result or an aggregate efficacy estimate. There is therefore no reported effect estimate, confidence interval, test statistic, or p-value on which to base a statistical conclusion. These quantities are not reported in the registry record.
The single-group design also limits what an observed change, if reportable, could establish. General statistical interpretation: without a concurrent comparison group, changes over time cannot be separated reliably from other influences, such as the natural course of illness, measurement variability, or changes in care. In this record, no efficacy result is available in any case, so even a descriptive within-group change cannot be evaluated.
The enrollment count is especially important for interpreting the scope of the evidence. A single participant cannot characterize how outcomes vary across the intended population. It also cannot support a stable estimate of an average treatment effect or the frequency of uncommon outcomes. The absence of reportable results is not evidence that the endpoint did not change; it means the registry does not disclose a result that would permit that question to be assessed.
The safety record lists 1 participant at risk in the Etrasimod group, 0 with a serious adverse event, 0 with an event in the other adverse-event category, and 0 deaths. Those are counts recorded for this small enrolled group, not precise estimates of event risk in a broader population. In particular, zero recorded events among the listed participants cannot establish that an event cannot occur or that the treatment is safe in other settings.
The study is listed as terminated. The reason for termination is not reported in the registry record, so the status alone does not explain why enrollment remained low or whether planned study activities were completed. Overall, the posted information documents a study objective, design, endpoint, and limited safety counts, but it does not provide a reportable efficacy result or a basis for comparative conclusions.
9. Statistical Methods Explained
The methods information must be read in light of the study’s single-group design and the fact that efficacy analyses were not conducted. The registry record identifies an exploratory endpoint but does not provide an analysis estimate, uncertainty measure, or test result. Statistical methods can explain what those quantities would mean in general; they cannot supply an endpoint result that is not reported.
What does a change-from-baseline endpoint describe?
In general, a change-from-baseline endpoint compares a participant’s assessment at a later time with that participant’s starting assessment. It is a way to describe within-person change. For this trial, the specified measure concerned endoscopic improvement or histologic healing, using endoscopy or flexible proctosigmoidoscopy. The record describes a further evaluation at week 12 only if signs of inflammation were present at screening. It does not report the actual baseline or follow-up assessments, the scoring rules, or the criteria used to classify improvement or healing.
When individual results are available, a group-level summary may describe the typical change and its variation across participants. In general, variability matters because participants can have different starting values and different changes. With enrollment of 1 and no efficacy analysis, the registry record does not give a group summary or an estimate of between-participant variability. It also does not report a confidence interval. A confidence interval, in general, expresses uncertainty around an estimate under the assumptions of the statistical method; it is not available for this endpoint in the record.
What does a single-group, open-label design permit?
A single-group study follows participants receiving the study intervention without a separate comparison group. Here, the intervention was APD334 active treatment for 12 weeks. Allocation was listed as not applicable, and masking as none. General statistical interpretation: a within-group measurement can describe what happened over time among those observed, but it does not by itself establish that the intervention caused a change. A concurrent comparison group can help distinguish intervention effects from other changes over time. This study’s record does not describe such a group.
Open-label means that masking was not used. In general, when treatment assignment is known, expectations or decisions about assessment and reporting can influence some outcomes. The degree to which this could affect this particular endpoint cannot be assessed from the registry record. Details of endpoint assessment procedures and safeguards are not reported in the registry record.
Why is there no inferential result to interpret?
Inferential analyses commonly combine an estimated effect with a measure of uncertainty, and sometimes a hypothesis test. Those methods require analyzable outcome information. The registry states that efficacy analyses were not conducted because enrollment was low (N=1), and that the single participant’s result cannot be reported to protect privacy. It lists 0 analyses. Thus, no reported efficacy estimate, confidence interval, or p-value is available. The record does not report whether any analysis was planned beyond the endpoint description or what statistical model would have been used.
General explanation: a p-value, when calculated, measures how compatible observed data are with a specified null model under the test’s assumptions. It does not measure the probability that a treatment works, nor does it show the size or practical importance of an effect. A confidence interval communicates uncertainty about an estimated quantity. Neither can be interpreted for the primary endpoint without a reportable analysis and result.
How should planning calculations be understood?
The registry’s stated planning framework describes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of an observed effect. It also distinguishes total event counts for time-to-event calculations from participants per arm for other calculations. These are planning assumptions, not evidence that this single-group trial tested a two-arm comparison. The registry record does not report an observed endpoint effect that can be interpreted as a treatment result, and any sample-size values associated with such a framework are planning illustrations rather than observed power.
In general, a planning calculation estimates the sample size needed under specified assumptions. It does not describe how many participants actually experienced an outcome, and it cannot compensate for a missing efficacy estimate. A calculation based on a fraction of an observed effect also depends on the effect used as its reference. The planning assumptions do not establish that the trial’s own design used two arms, equal allocation, or a particular analysis. The study is described instead as single-group, with allocation not applicable.
What is not documented?
The registry record does not report a detailed statistical analysis plan, the endpoint scoring method, a model for repeated measurements, methods for handling missing outcome data, or planned interim analyses. These details should not be inferred from the trial’s phase, proof-of-concept label, or stated endpoint. Without reportable efficacy data and further analysis details, the available record supports a description of the intended measurement and study structure, not an estimate of efficacy.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 17 outcome measures, while the primary endpoint is identified as exploratory. When a study assesses multiple outcomes, multiplicity can arise because repeated statistical tests increase the chance of finding an apparently notable result by chance. In general, investigators may address this by defining a hierarchy of outcomes, adjusting testing thresholds, or treating analyses as exploratory. The registry record does not report a multiplicity strategy, and efficacy analyses were not conducted.
The record lists 0 analyses and explains that efficacy analyses were not performed because enrollment was low (N=1). The primary endpoint result cannot be reported to protect privacy. No analysis population for efficacy, estimate, or test result is therefore available to interpret. The record does not state whether any alternative analysis population was defined or used; such details are not reported in the registry record.
Missing-data methods are also not reported in the registry record. There is no reported account of whether any scheduled assessment was missing, how missing observations would have been handled, or whether an imputation or sensitivity analysis was planned. The primary endpoint description makes the week 12 evaluation conditional on signs of inflammation at screening, but the record does not say whether that condition applied or whether the evaluation occurred. This should not be read as evidence that data were missing; the relevant assessment information is not reported.
These gaps matter because analysis choices can affect how estimates are interpreted, especially when outcomes are unavailable or multiple measures are considered. Here, however, the more fundamental limitation is that there is no reportable efficacy analysis. The registry does not provide enough information to assess multiplicity control, missing-data handling, or the composition of an efficacy analysis population.
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 |
|---|---|---|---|
| Etrasimod | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Etrasimod | 0 of 1 |
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 |
|---|---|
| Etrasimod | 0 of 1 |
The registry’s Etrasimod safety group lists 1 participant at risk. It records 0 participants with a serious adverse event, 0 with an event in the other adverse-event category, and 0 deaths. These are observed counts in the registry record for the enrolled group; they are not estimates for a larger population.
General statistical interpretation: zero recorded events in a small group does not establish that the underlying event risk is zero. A larger or longer study could observe events not seen in a small group, and the frequency of events in other populations cannot be inferred from these counts. The registry record does not provide event-specific details beyond the serious adverse-event terms, which are listed as none, or further information about the duration of safety observation.
The safety counts should therefore be read descriptively. They report what was recorded for the listed participant group, but do not establish comparative safety, because the study had no separate control group. The counts also do not support precise estimates of event frequency. The reason for study termination and additional safety-analysis details are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a phase 2a, proof-of-concept, open-label, single-group study was conducted to evaluate etrasimod in inflammatory bowel disease patients with active skin extra-intestinal manifestations. The intervention arm description specifies APD334 active treatment for 12 weeks. The primary endpoint was exploratory and concerned change from baseline in endoscopic improvement or histologic healing, using endoscopy or flexible proctosigmoidoscopy.
It does not establish what happened to the primary endpoint. Efficacy analyses were not conducted because enrollment was low (N=1), and the result for the single participant cannot be reported to protect privacy. There is no reportable estimate of change, no uncertainty interval, and no statistical test result. The lack of a disclosed efficacy result should not be interpreted as evidence of benefit, evidence of no benefit, or evidence that no change occurred.
The single-group design would not provide a randomized comparison even if a within-group result were available. In general, change over time in one group cannot be attributed solely to the intervention because other influences and natural variation are not separated by a concurrent control. The open-label design also used no masking. These features constrain causal interpretation, independently of the enrollment limitation.
The safety record reports 0 serious adverse events, 0 events in the other adverse-event category, and 0 deaths among 1 participant at risk. These counts are descriptive and do not establish the absence of risk in a broader population. The trial is listed as terminated, but the reason is not reported in the registry record.
Overall, the posted information documents the trial’s intent, structure, endpoint, termination status, and limited safety counts. It does not provide an analyzable efficacy result or comparative evidence. The record cannot answer whether etrasimod changed endoscopic or histologic findings in the intended population.
13. Why This Trial Matters Statistically
This study illustrates the difference between a trial’s scientific question and the evidence available to answer it. The stated aim was to evaluate etrasimod in inflammatory bowel disease patients with active skin extra-intestinal manifestations, using an exploratory endpoint related to endoscopic improvement or histologic healing. But enrollment was 1, efficacy analyses were not conducted, and the participant’s result cannot be reported. A clear research question does not by itself yield a reportable estimate.
It also illustrates why design features matter alongside endpoint selection. The study was open-label and single-group, with no randomized control comparison. General statistical interpretation: a single-group change can be descriptive, but a control group is important for distinguishing treatment-associated change from other influences. Here, the absence of a reportable efficacy result prevents even a descriptive assessment of change.
The record is also a reminder that low enrollment affects more than precision. With no reportable efficacy analysis, there is no estimate to accompany a confidence interval and no statistical test to interpret. Privacy considerations can also constrain reporting of individual-level results when enrollment is very small. The record explicitly states that the single participant’s result cannot be reported to protect privacy.
Finally, the safety counts show why event counts and population-level risk estimates are not interchangeable. The record lists no serious adverse events, other adverse events, or deaths in the enrolled group, but the group included only 1 participant. These observations describe that group and cannot precisely characterize safety in a broader population.
Statistically, the most informative conclusion is about the limits of the available evidence: the registry documents the planned question and study structure, but it does not provide an efficacy result that can be evaluated. That distinction helps prevent design intent, planning assumptions, or zero recorded events from being mistaken for evidence of a treatment effect.
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 main trial-specific limitation is enrollment of 1. The registry states that efficacy analyses were not conducted because enrollment was low and that the single participant’s result cannot be reported to protect privacy. Consequently, the primary endpoint has no reportable result, and the posted record cannot show the amount or direction of any change from baseline.
The study had a single group and no masking. Allocation was listed as not applicable. There is no randomized control group against which to compare outcomes, and any hypothetical within-group change would not by itself distinguish intervention effects from other influences over time. The record does not report a reason for termination, so the study’s status cannot be explained further from the available information.
The endpoint description leaves important operational details unspecified. The registry does not report the scoring system, criteria for improvement or healing, details of how endoscopy or flexible proctosigmoidoscopy assessments were conducted, or the method for combining endoscopic and histologic findings. The week 12 evaluation was conditional on signs of inflammation at screening, but whether that condition applied and whether the evaluation occurred are not reported in the registry record.
Other limitations in interpretation arise from details that are not reported in the registry record, including participant characteristics, treatment adherence, missing-data handling, the statistical analysis plan, multiplicity procedures, and the reason for termination. The safety counts are based on 1 participant and cannot provide precise estimates of event frequency. Together, these limitations mean the record supports description of the study’s intent and basic design, but not an estimate of efficacy or a broad assessment of safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy and Safety of Etrasimod (APD334) in Inflammatory Bowel Disease Patients With Active Skin Extra-intestinal Manifestations — NCT03139032.
- Registry record last updated 2020-12-31; status last verified 2020-12.
- Results first posted 2020-12-31.
- 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
NCT03139032 was a phase 2a, proof-of-concept, open-label, single-group study of APD334 (etrasimod) in inflammatory bowel disease patients with active skin extra-intestinal manifestations. The intervention description specifies active treatment for 12 weeks. The study began on 2017-07-17, had a primary completion date of 2017-12-06, enrolled 1 participant, and is listed as terminated.
The exploratory primary endpoint concerned change from baseline in endoscopic improvement or histologic healing, assessed using endoscopy or flexible proctosigmoidoscopy. A week 12 evaluation was planned only if signs of inflammation were present at screening. Efficacy analyses were not conducted because enrollment was low (N=1), and the participant’s result cannot be reported to protect privacy.
The safety record lists 1 participant at risk, 0 serious adverse events, 0 events in the other adverse-event category, and 0 deaths. The reason for termination and further analysis details are not reported in the registry record.