Study of DAXDILIMAB for the Treatment of Moderate-to-Severe Alopecia Areata: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of DAXDILIMAB for the Treatment of Moderate-to-Severe Alopecia Areata (NCT05368103), a na phase 2 study. The primary outcome is Percent Change From Baseline in SALT Score at Week 24.

2. Clinical Question

The study’s stated purpose was to assess preliminary efficacy, safety, tolerability, pharmacokinetics, and pharmacodynamics. The central statistical question is therefore descriptive: what change in the hair-loss score was recorded after participants received the study intervention, and how variable was that change? Because the design has no control group, the study cannot use a randomized between-group contrast to separate changes during the study from changes that might occur without the intervention. Its results, if reported, would characterize outcomes in this treated group rather than establish a causal comparison against another treatment or no treatment.

3. Trial Design

This was a Phase 2A, open-label, proof-of-concept trial of daxdilimab for moderate-to-severe alopecia areata. The registry record identifies the design as a single group, with no masking and no randomized allocation. It lists enrollment of 30 participants and a Daxdilimab 300 mg group. The intervention description specifies nine sets of daxdilimab injections over a total of 32 weeks. The study status is completed.

The registry record lists a study start date of 2022-04-27 and a primary completion date of 2023-08-07. These dates describe the recorded study timeline; they do not provide information about the timing of individual participant visits or the length of follow-up for each participant. The primary endpoint is assessed at Week 24, while the injection course is described as spanning 32 weeks.

In a single-group design, participants receive the same listed intervention and outcomes are measured over time. The primary endpoint uses baseline as its reference and evaluates percent change in SALT score at Week 24. This is not the same estimand as a difference between treatment groups: there is no concurrent control group against which to compare the change. Open-label status means the registry record does not describe masking of participants or investigators.

The record lists secondary SALT outcomes at multiple follow-up weeks. These include percent change from baseline, the percentage reaching a reduction of at least 50% from baseline, and percentages with absolute SALT scores at or below specified thresholds. Additional percent-change and response outcomes are listed for later weeks. The record does not report numerical outcome results or the analysis methods used for those secondary measures. The detailed visit schedule, eligibility criteria beyond the hair-loss range summarized in the study description, and other protocol details are not reported in the registry record.

The sample-size assumptions described in the record concern a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. That illustration is not a description of this single-group trial’s design. The trial’s own sample-size justification is not reported in the registry record, and a planning illustration should not be read as observed power or as evidence that the study had a particular ability to detect an effect.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Of the 55 participants who were screened for enrolment in the trial, 25 were screen failures. A total of 30 participants were enrolled and received daxdilimab.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety Analysis Set: Included all participants who received any dose of daxdilimab.

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 Analysis Set: Included all participants who received any dose of daxdilimab.

6. Primary Endpoint

The registry lists the primary outcome as Percent Change From Baseline in SALT Score at Week 24, measured over Baseline to Week 24.

The primary endpoint is percent change from baseline in SALT score at Week 24. SALT is a measure of the degree of scalp hair loss in alopecia areata. As described in the registry record, an investigator estimates hair loss in scalp quadrants, accounts for the scalp area represented by each quadrant, and combines the quadrant values into a total score ranging from 0 to 100. Higher scores indicate more severe symptoms. A decrease from baseline indicates a reduction in the score-defined extent of scalp hair loss.

Percent change expresses the Week 24 score in relation to the participant’s baseline score, rather than reporting only the Week 24 score in isolation. This can make the endpoint responsive to changes from each participant’s starting level. The record defines baseline as the last non-missing valid observation before the first dose of daxdilimab. It identifies the primary measure as a mean and names standard deviation as its dispersion measure.

As a general statistical point, a mean describes the average outcome across the analyzed participants, while a standard deviation describes variation among individual outcomes around that average. Together they can convey both the average direction and the spread of observed changes. They do not, by themselves, show the uncertainty of the estimated mean; that would ordinarily be described with an inferential measure such as a confidence interval. The registry record does not report the numerical mean, standard deviation, confidence interval, or a numerical Week 24 endpoint result.

The endpoint is useful for describing change over time in a measured disease feature. However, in this single-group, open-label study, a change in the score would be an observed within-group change, not a direct estimate of a difference versus a control group.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measure: percent change from baseline in SALT score at Week 24. The registry record identifies the summary parameter as a mean and the measure of dispersion as standard deviation. It does not report the numerical mean, standard deviation, confidence interval, or a hypothesis-test result. The discussion below explains the general statistical ideas involved; it does not infer which methods the investigators used beyond the descriptions in the registry record.

What does a mean describe?

For a continuous endpoint, the mean is the arithmetic average of the observed participant-level values included in an analysis. In this study, the endpoint is the change in score expressed as a percent change from baseline. A mean would summarize the average change in the analyzed group. It does not imply that every participant had a change equal to that average: individual outcomes may be more or less favorable, and may vary substantially around it.

The mean can be sensitive to unusually large or small observations. For that reason, interpretation is strengthened by knowing the distribution of individual values and the number of participants with an available endpoint. The registry record specifies standard deviation as the dispersion measure but does not report the distribution, endpoint analysis count, or individual outcomes. Those details are not reported in the registry record.

What does standard deviation describe?

Standard deviation describes the spread of observed values around their mean. A larger standard deviation indicates more variability among participant outcomes, while a smaller one indicates that observations are more closely grouped around the mean. It is not the same as the standard error or a confidence interval. Standard deviation describes participant-level variation; standard error and confidence intervals address uncertainty in an estimated summary, with their calculation depending on the analysis and data.

A confidence interval, as a general statistical concept, gives a range of values compatible with the data and the assumptions of the interval procedure. Its width reflects precision: a wider interval indicates less precision than a narrower interval. The registry record does not report a confidence interval for the primary endpoint. Without a numerical estimate and an uncertainty measure, it is not possible to characterize how precisely the mean Week 24 change was estimated.

How is baseline defined?

The registry record defines baseline as the last non-missing valid observation before the first dose of daxdilimab. The endpoint compares the Week 24 SALT score with this reference. Percent change is a relative expression of change, so its interpretation depends on the participant’s baseline value as well as the follow-up value. A group mean of participant-level percent changes is not necessarily the same quantity as a percent change calculated from group-level mean scores. The registry record names the endpoint as a mean percent change but does not further describe the precise computation or any adjustment.

As a general matter, baseline choice and the handling of follow-up observations can affect the analyzed values. The definition of baseline is stated, but details about the Week 24 assessment window, repeated-measures model, covariate adjustment, or other data-processing choices are not reported in the registry record.

What can a single-group comparison establish?

A before-and-after summary describes how measured outcomes differ over time within the participants included in the analysis. It does not, on its own, establish what would have happened to those participants over the same period in the absence of the intervention. A randomized control group can support a between-group contrast by providing a comparison under the study design. This record describes a single-group study without randomized allocation or masking; it does not report a concurrent control group.

Thus, even if the numerical mean change were available, the single-group endpoint would describe observed change among participants rather than a randomized treatment effect against a comparator. The open-label design also means that the registry does not describe masking of participants or investigators. The record does not state how outcome assessment or other potential sources of bias were addressed.

What does the planning illustration represent?

The record describes sample-size assumptions for a planning illustration computed from an observed effect. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. For non-time-to-event outcomes, the illustration is expressed as participants per arm for a stated power level. These assumptions describe a hypothetical planning exercise, not the design of the single-group trial described in the registry record.

Sample-size calculations estimate the amount of information that a design might need under assumed conditions. They depend on assumptions about the effect, variability, significance threshold, allocation, and analysis. If those assumptions differ from actual study conditions, the resulting illustration may not describe the study’s performance. A planning calculation is not observed power, and it does not tell the reader whether the actual trial produced a particular result. The trial’s own sample-size justification and detailed statistical plan are not reported in the registry record.

The registry record lists no analysis entries. It also does not specify the primary statistical test, any confidence-interval method, assumptions about the outcome distribution, or procedures for handling repeated measurements. Where these details are absent, no particular analysis should be attributed to the investigators. General explanations of means, variability, and precision help frame the endpoint, but they cannot substitute for the unreported numerical results and methods.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Daxdilimab 300 mg")
n   <- c(30)
m   <- c(-12.6)
sp  <- c(35.15)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Daxdilimab 300 mg  30  -12.600  35.150  -25.725  0.525

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary endpoint and numerous secondary SALT outcomes at different follow-up weeks. The secondary measures include percent change from baseline, reduction of at least 50% from baseline, and absolute SALT scores at or below several thresholds. Additional outcomes are listed at later follow-up weeks. Considering multiple outcomes and time points raises the general statistical issue of multiplicity: when many statistical tests are conducted, the chance of at least one apparently notable result can increase. This is a general consideration, not a claim that any particular test was performed or that a result was significant.

The registry record does not describe a multiplicity adjustment, a hierarchy for testing outcomes, or whether the secondary outcomes were intended to support formal confirmatory inference. Those procedures are not reported in the registry record. It also lists no analysis entries, and does not provide numerical results for the primary or secondary outcomes.

Missing-data handling is also not reported in the registry record. The record defines the Safety Analysis Set as all participants who received any dose of daxdilimab, and identifies it as the population for the primary outcome. It does not state how many participants had an available Week 24 SALT score, how many were included in the endpoint analysis, or how missing values were treated. General methods for missing data make different assumptions and can lead to different estimates; without the stated approach and relevant counts, the analysis cannot be reconstructed.

The baseline definition is given as the last non-missing valid observation before the first dose. However, the record does not explain how invalid or unavailable follow-up observations were handled, whether any imputation was used, or whether sensitivity analyses were conducted. The details of interim analyses are not reported in the registry record. These gaps limit assessment of the analysis process, but they do not establish that a particular method was or was not used.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry record reports the Daxdilimab 300 mg group with 30 participants at risk for serious adverse events and 0 affected. For other adverse events, it reports 30 at risk and 17 affected. The record lists 0 deaths. No top serious adverse-event terms are listed.

These figures are counts as reported in the registry record. They should not be interpreted as a complete account of every safety outcome: the record does not provide event descriptions for the 17 participants with other adverse events, their severity, timing, duration, or relationship to treatment. The absence of listed serious-event terms is consistent with the reported count of 0 participants affected by a serious adverse event, but the registry record does not provide further narrative detail.

As a general statistical point, safety counts describe what was recorded in the study group, while their interpretation depends on the definitions, observation period, and completeness of reporting. The study is single-group and has no concurrent control group, so these counts do not estimate a comparative safety difference. The safety figures should be read alongside the study’s size and design, without treating them as a comparison against another intervention.

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

The registry record establishes the study question and the way the primary outcome is defined: percent change from baseline in SALT score at Week 24, summarized as a mean, with standard deviation identified as the dispersion measure. It also specifies the baseline definition and explains the direction of the scale. These details make clear what a reported numerical result would represent: average change in a score of scalp hair loss among participants in the Safety Analysis Set.

However, the registry record does not report the numerical Week 24 endpoint result. The mean, standard deviation, and confidence interval are not reported in the registry record. Consequently, the posted information does not show the size or direction of the average change, how variable participant outcomes were, or how precisely the average was estimated. No claim about the magnitude of a change, or its statistical significance, can be made from the outcome definition alone.

Even with a numerical change, the design would remain important to interpretation. This was an open-label, single-group study with no randomized comparator. An observed difference between baseline and Week 24 would describe change within the analyzed group, but would not by itself determine how outcomes would have differed under a control condition. The registry record does not provide a randomized comparison.

The trial is described as a proof-of-concept study whose purpose included preliminary efficacy, safety, tolerability, pharmacokinetics, and pharmacodynamics. That stated purpose indicates the broad areas of assessment, but does not provide results for those domains. The record lists secondary SALT outcomes, but numerical secondary results are not reported in the registry record. The safety counts are reported separately and should be interpreted as descriptive counts within the group, not comparative estimates.

Accordingly, the record supports a description of the design, population, planned outcome measures, and certain safety counts. It does not support a conclusion about the primary outcome’s observed effect or precision. This distinction separates what the study set out to measure from what its posted results actually quantify.

14. Why This Trial Matters Statistically

Statistically, this trial is useful to examine because its primary outcome is a continuous score change over time in a single-group, open-label design. It illustrates the difference between defining a measurement and reporting an estimate: the SALT score, its direction, the baseline reference, the Week 24 time point, the mean summary, and the standard deviation are all specified, but the numerical endpoint result is not reported in the registry record. Without the estimate and its uncertainty, the primary outcome cannot be assessed quantitatively.

The study also highlights the distinction between within-group change and a treatment contrast. A before-and-after endpoint can describe the experience of the analyzed group, while a randomized comparator supports a different question about relative outcomes. The registry record identifies no concurrent control group and no randomized allocation. Readers therefore need to keep the design in view when interpreting any numerical change that might be reported elsewhere; the registry record itself does not provide such a primary result.

The secondary outcomes create another statistical consideration. They include multiple score thresholds, response definitions, and follow-up times. Those measures can describe different aspects of the outcome, but the record does not report their numerical results or explain any strategy for multiplicity. This makes the stated analysis plan and outcome reporting especially relevant to interpreting a set of results, if available.

The record’s planning illustration is also distinct from this study’s design. It is based on an observed effect and assumptions for a two-arm comparison, whereas the trial is recorded as single-group. This distinction shows why planning calculations must be read according to their assumptions and should not be treated as evidence of observed power or as a description of the trial’s own sample-size rationale.

Finally, the reported safety counts offer a limited descriptive view, not a comparative safety analysis. The record is informative about what was counted, but provides limited detail about event characteristics. Taken together, these features make transparent reporting of estimates, uncertainty, analysis populations, missing data, and outcome multiplicity important for interpretation.

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 most direct limitation of the registry record is that the primary endpoint’s numerical result is not reported. Although the endpoint, time point, mean summary, and standard deviation are identified, the estimated mean change and its precision cannot be assessed. Numerical results for the listed secondary SALT outcomes are also not reported in the registry record.

The study’s design is another important limitation for causal interpretation. It is listed as open-label and single-group, with no randomized allocation and no concurrent comparator. Any within-group score change would not provide a randomized estimate of the difference relative to a control condition. The registry record does not describe masking or other procedures intended to address the possible influence of awareness of treatment on outcome assessment.

The record defines the Safety Analysis Set as participants who received any dose, but does not report how many participants contributed data to the Week 24 endpoint analysis or whether that number differed from enrollment. The approach to missing follow-up measurements, invalid observations, or incomplete endpoint data is not reported in the registry record. The statistical model, inferential procedure, confidence-interval method, and any sensitivity analyses are also not reported.

There are multiple secondary outcomes and follow-up times, but the record does not state whether multiplicity was addressed, whether secondary analyses were formal or descriptive, or how the results were prioritized. The trial’s own sample-size justification and detailed analysis plan are not reported. The planning illustration described in the record has assumptions for a two-arm design and should not be treated as a justification for this single-group trial.

Safety reporting is limited to counts of participants affected and at risk, plus the deaths count. The record does not give descriptions, timing, severity, duration, or attribution for the other adverse events. These limitations concern the information reported in the registry record; they do not establish what may or may not have been documented elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of DAXDILIMAB for the Treatment of Moderate-to-Severe Alopecia Areata — NCT05368103.
• Registry record last updated 2025-01-07; status last verified 2024-12.
• Results first posted 2025-01-07.
• 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

The registry record describes a completed Phase 2A, open-label, proof-of-concept, single-group study of daxdilimab in moderate-to-severe alopecia areata. Enrollment was 30. The reported group is Daxdilimab 300 mg, with nine sets of injections over a total of 32 weeks. The study is listed with no masking and no randomized allocation.

The primary outcome is percent change from baseline in SALT score at Week 24, summarized as a mean with standard deviation. Baseline is the last non-missing valid observation before the first dose. A decrease in SALT score indicates a reduction in score-defined scalp hair loss. The numerical primary endpoint result and its precision are not reported in the registry record.

Secondary SALT outcomes are listed across multiple follow-up weeks, but their numerical results are not reported. For safety, 0 of 30 participants were reported affected by serious adverse events, 17 of 30 were affected by other adverse events, and the record lists 0 deaths. The record does not report the trial’s own sample-size justification, detailed statistical analysis plan, or approach to missing data and multiplicity.