Study of OSE-127 vs Placebo in Patients With Moderate to Severe Active Ulcerative Colitis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of OSE-127 vs Placebo in Patients With Moderate to Severe Active Ulcerative Colitis (NCT04882007), a randomized phase 2 study. The primary outcome is Change From Baseline in Modified Mayo Score (MMS) at Week 10.

2. Clinical Question

3. Trial Design

NCT04882007 is listed as a completed phase 2 study sponsored by OSE Immunotherapeutics. The record lists a start date of 2020-10-02 and primary completion on 2024-04-30. Its title describes a randomized, double-blind study of OSE-127 versus placebo in people with moderate to severe active ulcerative colitis. The design is listed as randomized, quadruple-masked, and parallel-group. The brief summary also describes a multicenter, placebo-controlled study.

The registry describes three induction groups: OSE-127 high dose, OSE-127 low dose, and placebo. Each induction description specifies three intravenous infusions at weeks 0, 2, and 6. The high-dose group also has an optional extension description specifying seven additional infusions at weeks 10, 14, 18, 22, 26, 30, and 34. The registry does not report how many participants entered or completed that optional extension in the registry record recorded for this analysis.

There is a naming difference between parts of the record: the study title and intervention descriptions use OSE-127, while the posted outcome arms are labelled Lusvertikimab 850 mg and Lusvertikimab 450 mg. The record does not explain this difference, so the labels are retained as they appear in the respective descriptions rather than assuming a relationship beyond the record.

The enrollment is listed as 136. The primary endpoint analysis uses the Full Analysis Set, described as randomized patients with ulcerative colitis who received at least one dose of study treatment; the description notes two exclusions for Crohn's Disease. The registry record does not report the allocation ratio, the number assigned to each arm at randomization, the detailed conduct of masking, or the planned sample-size justification. These omissions limit what can be reconstructed about design decisions from the registry alone.

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.

Double-Blind Induction Period

Open-Label Extension

Analysis population for the primary outcome, as defined in the registry: Full Analysis Set: all randomized patients with Ulcerative Colitis who received at least one dose of study treatment (2 patients excluded for Crohn's Disease).

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: Full Analysis Set: all randomized patients with Ulcerative Colitis who received at least one dose of study treatment (2 patients excluded for Crohn's Disease).

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Modified Mayo Score (MMS) at Week 10, measured over From Baseline to Week 10.

The primary endpoint is change from baseline in the modified Mayo Score at week 10. The Mayo Score assesses ulcerative colitis disease activity. This modified version has three domains: stool frequency and rectal bleeding, answered by the patient, and mucosal appearance at endoscopy, assessed by an endoscopist. Each domain is graded from 0 to 3, and the total ranges from 0 to 9. Higher values represent worse outcomes.

Change from baseline provides a way to compare how the score shifts over the induction period, rather than considering only the week 10 score or only the initial score. A negative mean change corresponds to a lower score at week 10 on average. The registry reports least-squares means with 95% confidence intervals for each group, and ANCOVA comparisons of each active group with placebo. These adjusted comparisons are the primary inferential results reported in the record.

Using a composite disease activity measure can capture more than one aspect of ulcerative colitis, combining patient-reported symptoms with an endoscopic assessment. That breadth is useful for describing disease activity, but a total score can conceal differences among its component domains. The record does not provide the component-level primary endpoint results in the registry record used. Nor does it state a threshold for interpreting a particular score change as clinically important. Statistical evidence about a difference in mean change therefore should be distinguished from evidence about the practical importance of that difference for patients.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is a change in a numerical score. The registry reports least-squares means for the three arms and uses analysis of covariance (ANCOVA) for the active-versus-placebo comparisons. In general, ANCOVA compares outcomes while accounting for variables included in the model. The registry record identifies ANCOVA as the method but does not report the full model specification, which variables were included, or how any assumptions were checked. Those details are needed to reproduce or fully assess the adjustment.

What do the least-squares means describe?

In general, a least-squares mean is a model-based estimate of a group mean after accounting for the covariates specified in the model. It is not necessarily the same as the simple arithmetic mean of the observed values. The registry reports each group’s estimate and 95% confidence interval, and then reports ANCOVA least-squares mean differences comparing each active arm with placebo. A contrast is the estimated difference between groups under that model. The negative reported contrasts indicate that the estimated change was more negative in the active group than in placebo, given the score direction and the reported contrast labels.

How should a confidence interval be read?

In general, a confidence interval gives a range of estimates compatible with the observed data and the statistical model at the stated confidence level. It represents uncertainty about the estimated population quantity; it is not a range containing a known proportion of individual participant outcomes. A narrower interval indicates greater precision than a wider interval, all else equal. For the primary contrasts, the registry reports 95% intervals. Intervals that include zero are compatible with no difference under this model at that confidence level; intervals that do not include zero are evidence of a difference under the model. This interpretation does not settle whether the size of a difference matters clinically.

What do p-values add?

In general, a p-value describes how incompatible the observed data, or more extreme data, are with a specified null hypothesis under the assumptions of the analysis. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. The primary p-values are reported alongside estimates and confidence intervals, which gives more context than a significance label alone. The record does not report whether the primary comparisons were adjusted for multiple testing across arms or endpoints.

How do the binary outcomes differ?

Clinical remission and endoscopic remission are reported as percentages, and the sponsor’s analyses use logistic regression with odds ratios. In general, logistic regression models the odds of a binary outcome, and an odds ratio compares those odds between groups. An odds ratio is not a percentage-point difference and can be difficult to interpret without the underlying event proportions. The posted results also permit simple unadjusted comparisons of observed proportions. Those re-calculations are descriptive, not replacements for the sponsor’s model-based analyses; they do not account for covariates or any other adjustments. The registry record’s adjusted results take precedence when describing the sponsor’s analysis.

For binary endpoints, relatively few events can make estimates imprecise. Confidence intervals can be wide, reflecting uncertainty, and a result may be sensitive to the analytic method. In general, methods for comparing proportions can differ in assumptions and in how they handle sparse data. The record identifies logistic regression for the sponsor’s analyses but does not report all model details or the handling of potential model limitations. The posted unadjusted re-calculations should therefore be understood as a separate, simplified view rather than as the trial’s primary analysis.

What do the sample-size illustrations mean?

In general, a sample-size calculation estimates how many participants would be needed under chosen assumptions to detect a target effect with a chosen probability of rejecting a null hypothesis when that effect is present. The record’s planning illustrations use the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They show planning quantities for fractions of the observed effect. They are illustrations, not evidence of the study’s original design assumptions, and not observed power. The registry record does not report the trial’s own sample-size justification or indicate that those illustrative assumptions were used in planning the study.

Power is a design property conditional on assumptions about the effect, variability, significance level, and analysis. It cannot be calculated after observing the results in a way that adds information beyond the estimate and its uncertainty. Accordingly, the planning values should not be read as evidence that the completed study had a particular probability of detecting its observed effect.

Finally, the analysis population and missing-data procedures matter. The primary population is described as randomized participants who received at least one dose, with two Crohn's Disease exclusions. The registry record does not report the handling of missing week 10 scores, the amount of missing outcome data, sensitivity analyses, or whether the analysis followed an intention-to-treat principle as commonly defined. These gaps restrict assessment of the assumptions behind the estimates.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary comparisons as ANCOVA least-squares mean differences, with 95% confidence intervals and p-values. These are the principal inferential results for the modified Mayo Score and should be distinguished from simple re-calculations based on posted summaries. The registry record does not flag a discrepancy for the primary results, so there is no stated conflict requiring the sponsor’s analysis to be set aside.

For the secondary binary outcomes, the sponsor reports logistic-regression odds ratios and associated confidence intervals and p-values. Simple unadjusted re-calculations from posted percentages and event counts give risk-difference estimates and unadjusted p-values; these answer a different, less adjusted question. They may differ from the sponsor’s model-based estimates because the methods and estimands are not the same. No discrepancy is flagged, but the sponsor’s own analysis remains the appropriate description of the analyses reported by the trial.

Neither form of analysis resolves the record’s missing details about covariate adjustment, missing outcomes, or multiplicity. The registry record does not provide enough statistical-plan detail to establish how the sponsor’s methods were prespecified or how all possible sources of uncertainty were handled. The re-calculations are not a correction to the sponsor’s results and should not be treated as a substitute for the reported analysis.

11. Multiplicity, Missing Data and Analysis Populations

The registry record reports primary comparisons against placebo for two active-treatment groups and two secondary outcomes, but does not report a multiplicity adjustment or testing hierarchy. In general, testing multiple hypotheses increases the chance that at least one result will appear statistically notable even when there is no true effect for any hypothesis in the family. Procedures for controlling that risk depend on which outcomes and comparisons were prespecified as confirmatory and how they were ordered or grouped. That information is not reported in the registry record.

Consequently, the reported p-values describe their individual comparisons under the stated analyses, but should not automatically be treated as family-wise error-controlled evidence across all endpoints and arms. This is especially relevant to secondary analyses, which can be useful for describing patterns but carry less inferential weight without a documented multiplicity plan. The record also does not report whether interim analyses were planned or conducted.

Missing outcome data can affect both the estimated treatment effects and their uncertainty. The endpoint is measured at baseline and week 10, but the registry record does not report the amount or pattern of missing week 10 observations, the method used to handle missing values, or sensitivity analyses addressing alternative assumptions. It is therefore not possible to assess from this record whether missingness could have changed the conclusions.

The stated Full Analysis Set includes randomized patients who received at least one dose of study treatment; the description says two patients were excluded for Crohn's Disease. The record does not report a separate intention-to-treat analysis, a per-protocol population, or detailed rules for inclusion in each secondary analysis. It also does not provide enough information to establish how participants who discontinued treatment or entered the optional extension were handled for the week 10 analyses. These reporting gaps matter because analysis populations and missing-data assumptions define the precise question an estimate answers.

The registry record does not report the protocol’s full statistical analysis plan, sample-size justification, interim-analysis details, or complete covariate specification. Without those items, the extent to which the posted analysis follows prespecified choices cannot be assessed from the registry results alone.

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 2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: colitis ulcerative (2.8%), anal ulcer (2.8%), asymptomatic covid-19 (2.8%), chest pain (2.0%), covid-19 pneumonia (2.0%).

The registry reports serious adverse events during the induction period for the 850 mg group, 450 mg group, and placebo group, and also reports a separate high-dose open-label extension period. The induction groups each have a reported risk set and serious adverse event count; the extension has its own risk set and count. These are period-specific descriptions, not directly interchangeable comparisons: the extension is open-label and represents a different treatment period. The record does not provide enough detail to determine individual exposure duration or whether participants contributed to more than one period.

One death is reported in the placebo induction group; no deaths are reported in the other listed groups. The registry’s listing does not establish cause, relatedness to treatment, or whether the event was considered treatment-emergent. Those details are not reported in the registry record. The serious-event terms shown among the leading terms include ulcerative colitis, anal ulcer, asymptomatic Covid-19, chest pain, Covid-19 pneumonia, and uterine leiomyoma, with percentages recorded for those terms. The record does not assign those term percentages to particular arms in the registry record used.

Adverse-event counts are descriptive safety information. They do not by themselves establish that a treatment caused an event, and they cannot be interpreted without considering exposure, event definitions, follow-up, and the way events were collected. The record does not provide a complete causal assessment or enough detail to draw comparative safety conclusions from these figures alone.

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

The results describe estimated changes in modified Mayo Score over the period ending at week 10 and comparisons of those changes between each active-treatment group and placebo. The reported active-versus-placebo estimates are negative, with 95% confidence intervals that do not include zero under the ANCOVA analyses. This is statistical evidence of differences in mean change under the reported model. It does not establish that the estimated differences are clinically important, because the registry record does not state a clinically important difference threshold.

The estimates also do not describe every participant’s outcome. Group means can conceal variation, including participants whose scores changed in different directions. The confidence intervals concern uncertainty in estimated group contrasts, not the distribution of individual responses. The record does not provide enough detail to assess missing week 10 outcomes or all assumptions behind the model.

Secondary remission outcomes show a broadly similar direction in the posted percentages, but they have their own limitations as binary outcomes and are subject to the uncertainty of multiple comparisons. Unadjusted secondary results should not be treated as equivalent to the sponsor’s adjusted analyses or as independent confirmation without a documented testing plan.

These findings do not determine what would happen beyond the reported endpoint and follow-up, and the record does not establish long-term effects or outcomes in particular patient subgroups. The safety information is also descriptive and does not establish causality. Taken together, the registry results are a statistical account of one phase 2 randomized study, rather than a basis for medical advice or a definitive conclusion about benefit and risk.

14. Why This Trial Matters Statistically

This study illustrates why an estimated effect, its uncertainty, and the analysis plan should be read together. The primary outcome is a continuous score, and the registry reports model-based group estimates and adjusted comparisons. The confidence intervals show that the point estimates are not exact measurements of an underlying effect; they express uncertainty under the fitted analysis. Reporting the contrast and its interval gives more information about direction and precision than a p-value alone.

The record also highlights the distinction between a primary endpoint and secondary endpoints. A continuous composite score and binary remission measures can provide complementary descriptions, but they are not interchangeable. Secondary outcomes may support an overall pattern while still carrying less evidential weight when a multiplicity plan is not reported. Likewise, unadjusted re-calculations can help describe posted summaries, but they answer a simpler question than the sponsor’s adjusted regression analyses.

Design interpretation depends on transparency about who was analyzed, how missing observations were handled, which comparisons were planned, and how sample size was justified. The registry identifies the primary analysis population and the ANCOVA method, yet does not report several details needed to assess reproducibility and robustness. That distinction is important: a result can be statistically interpretable while the reporting record remains incomplete.

Finally, the record’s different naming conventions for the intervention and posted arms show why careful description matters. Statistical interpretation should preserve what the registry states, avoid assuming undocumented relationships, and separate observed patterns from claims that go beyond the recorded evidence.

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 has important reporting gaps for interpreting this trial. It identifies ANCOVA for the primary comparisons, but does not provide the full model specification, covariates, diagnostic checks, or the statistical analysis plan. The record also does not report whether multiplicity was controlled across the primary and secondary comparisons, or whether any interim analyses were planned or conducted.

Information about missing outcomes is limited. The amount and pattern of missing week 10 data, the imputation or other missing-data approach, and sensitivity analyses are not reported in the registry record. The listed primary analysis population excludes two patients for Crohn's Disease, but the record does not fully describe analysis populations for every endpoint or how discontinuation and optional-extension participation affected the analyses.

The intervention naming is not consistent across the record: OSE-127 appears in the study title and intervention descriptions, while the posted result arms use Lusvertikimab labels. The registry record does not explain this difference. It also does not report detailed information on the proportion entering or completing the optional extension, treatment exposure by participant, or the relationship of adverse events to treatment.

The primary endpoint is a composite score, but the component-specific primary results and a threshold for clinical importance are not reported in the registry record used. The remission outcomes are secondary and their inferential interpretation is limited by the absence of a reported multiplicity plan. Finally, safety counts are descriptive; the registry entries do not establish causality or provide a complete comparative safety assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of OSE-127 vs Placebo in Patients With Moderate to Severe Active Ulcerative Colitis — NCT04882007.
• Registry record last updated 2026-06-23; status last verified 2026-05.
• Results first posted 2026-06-23.
• 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

NCT04882007 is a completed phase 2 randomized, quadruple-masked, parallel-group study of OSE-127 versus placebo in moderate to severe active ulcerative colitis. The primary endpoint is change from baseline in modified Mayo Score at week 10, with ANCOVA comparisons reported for each active arm versus placebo. The registry’s primary estimates favor more negative mean score changes in the active arms than in placebo, and the reported 95% confidence intervals for both contrasts exclude zero.

Week 10 clinical and endoscopic remission are also reported as secondary outcomes. Their overall pattern is directionally consistent with the primary outcome, but the record does not report a multiplicity plan. Interpretation is further limited by unreported details about missing data, model specification, and the trial’s sample-size justification. Safety counts are descriptive and do not establish causality.