Targeting IL-17A for Treatment-Resistant Depression: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Targeting IL-17A for Treatment-Resistant Depression (NCT04979910), a na phase 2 study. The primary outcome is Number of Participants Who Dropped-out.

2. Clinical Question

This is a feasibility-focused question rather than a randomized comparison of ixekizumab with another treatment or with a control condition. The registry identifies the study as Phase 2 and describes its aim as testing ixekizumab in patients with treatment-resistant depression. Its primary endpoint counts participants who dropped out; the endpoint description links treatment completion to receipt of all scheduled injections.

The record also lists secondary measures covering depression symptoms, pleasure, global clinical impression, suicidality, and anxiety. These measures describe other areas of interest, but the registry record does not include their numerical results. The primary question can therefore be stated from the planned endpoint, while the posted information does not establish how many participants completed the treatment schedule or dropped out.

3. Trial Design

The registry describes a Phase 2, single-group study of ixekizumab for treatment-resistant depression. Enrollment was 7, and the listed condition is Major Depressive Disorder. The study is marked completed. Its start date is 2021-08-27 and its primary completion date is 2024-04-12.

All participants were assigned to the ixekizumab intervention as described in the registry; there is no separate comparator group listed. Allocation is recorded as NA, and masking as NONE. Those details matter to interpretation: the record does not describe a randomized, blinded comparison, so the study cannot use a concurrent control group to separate changes during the study from other explanations.

The intervention schedule was ixekizumab 160 mg, given as two 80 mg injections, at Week 0, followed by 80 mg at Weeks 2 and 4 via the subcutaneous route. The primary endpoint timeframe was 6 weeks. The endpoint description defines completion as receiving all three injections and says drop-out rates would be calculated.

The registry lists 10 outcome measures, including the primary measure and secondary measures. It also lists no analyses. Details such as the planned analysis population, the statistical procedures, and the handling of missing observations are not reported in the registry record. The enrollment figure describes the study size; it does not, by itself, show how many participants contributed data to each measure.

The calculated tables, plots, and planning section can help readers inspect the posted information, but they do not change the underlying design. In particular, any planning illustration should not be read as the study’s original design justification or as evidence that the study had a particular probability of detecting an effect. A sample-size justification is not 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

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Who Dropped-out, measured over 6 weeks.

The primary endpoint is the number of participants who dropped out, with a timeframe of 6 weeks. The registry’s description connects this count to treatment completion: completion means receiving all three ixekizumab injections, scheduled at Week 0, Week 2, and Week 4. Drop-out rates were to be calculated to assess safety and feasibility.

A completion or drop-out measure is useful in a feasibility study because it describes whether participants stayed in the study long enough to receive the intended treatment schedule. It can also give context for whether the study procedures and treatment visits were manageable for participants. As a general statistical point, a count is a direct summary of how many participants experienced the defined event; it does not, on its own, explain why an event occurred.

The registry record does not report the observed number of participants who dropped out or completed all injections. Therefore, the endpoint’s definition is available, but its observed result cannot be described from this record. The count should also not be confused with the adverse-event counts: those are recorded separately, and the registry does not state that an adverse event caused a participant to drop out.

Nor does completion establish a change in depression symptoms. Symptom measures appear among the listed secondary outcomes, but their results are not reported in the registry record. The endpoint is about treatment completion, not an estimate of symptom benefit.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record gives the broad design and endpoint but does not report a detailed statistical analysis plan. The explanation below distinguishes what the record states from general statistical principles that help interpret this kind of study.

What does a single-group design show?

The study is listed as single-group, with allocation recorded as NA and masking as NONE. In a single-group study, observations are collected among participants receiving the listed intervention rather than compared with a concurrent control group. This can describe treatment completion and events observed during the study. As a general statistical point, the absence of a control group limits causal interpretation: changes may have explanations other than the intervention, and the design cannot directly estimate a between-group treatment contrast.

Masking is also listed as NONE. Masking generally means keeping participants, investigators, or other people involved in a study unaware of treatment assignment. In a single-group study, the registry’s entry still indicates that masking was not used. The record does not give further detail about which people knew the treatment or how outcomes were assessed.

What does the primary count represent?

The primary outcome is the number of participants who dropped out. Its description says treatment completion is measured by receipt of all three ixekizumab injections, with the schedule spanning the stated 6-week timeframe, and that drop-out rates would be calculated. A count is straightforward to understand, but its interpretation depends on a clear event definition and complete follow-up. The record gives the completion definition but does not report the observed dropout count, the number completing treatment, or a detailed rule for classifying participants whose status was unknown.

As a general statistical point, a rate requires a numerator and a denominator defined for the same outcome and observation period. The adverse-event summary has its own at-risk counts, but those should not be substituted for the missing primary endpoint result. The registry does not report whether any adverse event led to dropout.

What can the adverse-event counts tell us?

The posted safety summary records participants at risk and participants affected. It lists 0 serious adverse events, 4 participants with other adverse events, and 0 deaths, each with 7 at risk. These counts describe what the registry records in this group. They do not tell the reader how many separate events occurred, because the displayed figures are participant counts, or what the event terms were. No serious event terms are listed, and the registry does not provide further terms for other events in the registry record.

In general, adverse-event summaries are descriptive unless the record also supplies a comparison and an analysis that supports a comparative conclusion. A zero count in a small study does not prove that an event cannot occur. Likewise, the presence of other events does not establish that the intervention caused them. Attribution, timing, event definitions, and the completeness of reporting all matter, and those details are not reported in the registry record.

How should uncertainty be understood?

A confidence interval is a statistical range intended to show the uncertainty around an estimate under a specified method. It is not reported for the primary endpoint or the adverse-event counts. Without an interval, the reader has the posted counts but not a registry-reported measure of their statistical precision. As a general principle, small samples often leave substantial uncertainty around event frequencies; a count should not be treated as a precise estimate for a wider population.

The registry lists no analyses. It therefore does not report inferential procedures, adjusted estimates, p-values, confidence intervals, or a model for the listed outcomes. It also does not report an interim-analysis plan. These omissions prevent reconstruction of a formal statistical analysis from the registry record.

What do the listed outcomes imply?

The record lists 10 outcome measures, including the dropout endpoint and measures of depression symptoms, pleasure, global clinical impression, suicidality, and anxiety. A prespecified outcome list and a results set are different things: listing a measure does not show its observed values or whether an analysis was performed. Numerical results for the secondary measures are not reported in the registry record.

Multiplicity refers, in general, to the interpretive challenge created when multiple outcomes or multiple statistical tests are examined. If many tests are performed, the chance of at least one apparently notable result can increase unless the analysis accounts for that testing. The registry record does not report a multiplicity plan or any analyses, so it is not possible to assess whether or how multiplicity was addressed.

What are the planning illustrations?

The sample-size section contains planning illustrations based on an observed effect, under stated assumptions: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such calculations are hypothetical planning exercises, not observed power and not the trial’s own design justification. The study itself is recorded as single-group, so an equal-allocation two-arm illustration is not a description of its actual design. A sample-size justification for the trial is not reported in the registry record.

More generally, planning calculations depend on assumptions about the effect to detect, the design, and the statistical method. They do not establish that the study was adequately powered, and they cannot replace results or uncertainty estimates. Here, the record’s missing primary outcome result and absent analysis details limit what can be concluded from any such illustration.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Ixekizumab")
n      <- c(7)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Ixekizumab  7  0  0.0  0.0  41.0  0.0  35.4  0.3  36.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 10 outcome measures, including the primary dropout endpoint and secondary measures of depression symptoms, pleasure, global clinical impression, suicidality, and anxiety. It lists no analyses. The registry record does not report whether these measures were analyzed, which outcomes were prioritized in any analysis, or whether a multiplicity procedure was planned. Because numerical results for the secondary measures are not reported, readers cannot assess patterns across those outcomes or determine how multiple testing may have affected interpretation.

As a general statistical point, multiplicity arises when several outcomes or tests are considered. If analyses are performed across many outcomes, the chance of finding an apparently notable result can increase. A prespecified hierarchy or adjustment can help manage this issue, but neither is described in the registry record. It would be inappropriate to assume that a particular approach was used.

Missing-data handling is also not reported in the registry record. The record does not describe how participants with incomplete follow-up, missing symptom scores, or uncertain treatment-completion status were handled. The analysis populations are not reported either; the record does not say which participants were included in any endpoint analysis. Since no analyses are listed, there are no posted analytic denominators or descriptions of exclusions to evaluate.

These gaps matter for interpretation. The enrolled group of 7 is not necessarily the number contributing data to every outcome, and the available adverse-event at-risk counts do not establish the analysis population for the primary endpoint. The record also does not state how missing observations were classified for the dropout measure. As a result, the endpoint definition is known, but the analysis procedures and the completeness of outcome data cannot be assessed from the registry record.

12. 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 non-serious adverse event terms

The registry safety summary lists 0 participants with serious adverse events among 7 at risk, 4 participants with other adverse events among 7 at risk, and 0 deaths among 7 at risk. These are participant counts recorded for the ixekizumab group. The serious-event listing contains no event terms.

The “other” category is separate from the serious-event count. The registry summary does not provide the event terms or additional detail about those events in the record. It also does not say whether events were considered related to ixekizumab, when they occurred, whether they resolved, or whether any participant experienced more than one event. Participant counts should not be mistaken for counts of distinct event episodes.

As a general statistical point, absence of a recorded event in a small group does not establish that the event is impossible or that the intervention caused no risk. These descriptive figures do not compare ixekizumab with another group, and they cannot by themselves establish causation. The registry record also does not link adverse events to the primary dropout endpoint, so the safety counts should not be used to infer how many participants discontinued treatment.

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

This record establishes that a completed Phase 2, single-group study of ixekizumab in treatment-resistant depression enrolled 7 participants. It specifies the injection schedule, identifies treatment completion and dropout as the primary endpoint, and provides a limited adverse-event summary. Those details help readers understand what the study set out to document and what information appears in the registry.

The posted information does not report the observed primary endpoint result. In particular, it does not state how many participants dropped out or completed all three injections. It also does not provide numerical results for the listed secondary measures. Therefore, this record cannot show how depression symptoms, pleasure, global clinical impression, suicidality, or anxiety changed during the study.

The safety summary records 0 participants with serious adverse events, 4 with other adverse events, and 0 deaths, each among 7 at risk. These figures are descriptive and do not establish whether events were caused by the intervention. There is no comparator group, and the registry lists no analyses. The record also does not report confidence intervals, p-values, or detailed event terms.

As a general statistical point, the purpose of a study and the information reported in its record are not the same as evidence for a comparative treatment effect. A single-group study can describe its participants’ recorded experiences, but without a comparator it cannot determine what would have happened under another condition. In this case, the missing primary result and absent secondary outcome results further limit interpretation.

The posted data do not establish that ixekizumab improved symptoms, did not improve symptoms, or caused the recorded adverse events. They also do not provide a precise estimate of treatment completion or event frequency for a broader population. The conclusions should remain limited to the design and descriptive figures that the registry records.

14. Why This Trial Matters Statistically

This study is statistically notable for the contrast between a clearly described feasibility endpoint and the limited outcome results available in the registry record. The primary question is framed around treatment completion, defined through receipt of all three ixekizumab injections, and dropout during a 6-week timeframe. That is a directly interpretable endpoint for a study concerned with safety and feasibility. However, the observed number of dropouts and the number completing treatment are not reported, so the central feasibility result cannot be read from the posted record.

The single-group design is also important. It supports descriptive reporting about the participants enrolled, but it does not provide a concurrent control for comparison. This limits what can be inferred about causes of changes or events. The registry’s listing of no analyses means there is no posted inferential analysis to supplement the descriptive record.

The safety summary shows how counts can be informative while still being limited: the record provides numbers for serious events, other events, and deaths, but not event terms for the other category or details about attribution. With enrollment of 7, these figures describe this group rather than supplying a precise estimate for a wider population. A zero serious-event count is a statement about what is recorded here, not proof that serious events cannot occur.

Finally, the record lists several secondary domains but does not report their numerical results. This is a useful reminder that an outcome list is not a results analysis. Without observed values, analysis details, missing-data procedures, or a multiplicity plan, readers cannot evaluate those measures statistically. The trial therefore illustrates why design, outcome definitions, and complete results reporting all matter when interpreting a small clinical study.

15. 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 describes a single-group study with no listed comparator and no masking. Without a concurrent comparison group, descriptive observations cannot isolate the effect of ixekizumab from other explanations. The study enrolled 7 participants, so the posted counts describe a small group and may not precisely characterize event frequencies beyond it.

The most direct limitation for interpreting the primary endpoint is that its observed result is not reported in the registry record. The endpoint is defined as the number of participants who dropped out during the 6-week timeframe, with completion tied to receipt of all three injections, but the record does not state the number who dropped out or completed treatment. It also does not report how uncertain or incomplete completion status was handled.

The registry lists no analyses, and numerical results for the listed secondary measures are not reported. Analysis populations, missing-data procedures, statistical methods, and multiplicity handling are not reported in the registry record. These omissions prevent assessment of how outcomes were analyzed or whether missing observations affected the results.

The safety information is limited to participant counts. The serious-event and death counts are listed as zero, while 4 participants are listed with other adverse events. Event terms for the other category, timing, severity details, attribution, and any relationship to dropout are not reported in the registry record. The record also does not provide confidence intervals for these counts.

Finally, the registry does not report a sample-size justification or interim-analysis plan. Any sample-size illustrations on the page are planning exercises, not evidence of the original study rationale or observed power. These limitations mean the record supports a description of the design and selected safety counts, but not a full statistical assessment of feasibility or symptom outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Targeting IL-17A for Treatment-Resistant Depression — NCT04979910.
• Registry record last updated 2025-05-20; status last verified 2025-05.
• Results first posted 2025-05-20.
• 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.

19. Record Summary

This is the registry record for NCT04979910, titled “Targeting IL-17A for Treatment-Resistant Depression.” The official title describes an experimental therapeutics study of a monoclonal antibody against interleukin 17A in patients with treatment-resistant depression. The sponsor is Icahn School of Medicine at Mount Sinai.

The study is listed as Phase 2, completed, and single-group, with enrollment of 7. Allocation is recorded as NA and masking as NONE. The intervention was ixekizumab, given subcutaneously as 160 mg at Week 0 followed by 80 mg at Weeks 2 and 4. The primary endpoint was the number of participants who dropped out during a 6-week timeframe, tied to receipt of all three injections.

The registry lists 10 outcome measures and no analyses. It reports 0 participants with serious adverse events, 4 with other adverse events, and 0 deaths among 7 at risk. The observed primary endpoint result, secondary outcome results, analysis methods, and detailed event terms are not reported in the registry record.