A Study of Intravenous Vedolizumab Administered Every 4 Weeks in Japanese Participants With Moderate to Severe Ulcerative Colitis or Crohn's Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Intravenous Vedolizumab Administered Every 4 Weeks in Japanese Participants With Moderate to Severe Ulcerative Colitis or Crohn's Disease (NCT04738942), a non-randomized phase 3 study. The primary outcome is UC Cohort: Percentage of Participants With Clinical Response at Week 12 Based on Modified Mayo Score.

2. Clinical Question

3. Trial Design

This is an open-label, Phase 3, nonrandomized, parallel study of intravenous vedolizumab administered every four weeks. It includes Japanese participants with moderate to severe UC or CD who experienced secondary loss of response during maintenance treatment with vedolizumab every eight weeks. The registry lists Takeda as the sponsor and the study location as Japan.

The intervention is vedolizumab 300 mg by IV infusion. The treatment phase is described as lasting up to 12 weeks, with assessment of symptom improvement after three infusions. Participants whose symptoms improve may continue every-four-week treatment in an extension phase until marketing approval of IV vedolizumab every four weeks or study termination. Participants without improvement stop treatment and have a final clinic visit 16 weeks after their last infusion. The description also states that participants have a phone follow-up six months after their last infusion to check for health problems.

The registry lists enrollment as 56. The study status is active, not recruiting. The listed start date is 2021-06-04, and the primary completion date is 2025-05-30. These record details do not establish that all study follow-up or analysis is complete.

Because allocation is nonrandomized and masking is absent, the study does not provide a randomized, blinded comparison of treatment strategies. The UC and CD cohorts are defined by disease, and both receive vedolizumab. Their outcomes should therefore be read as cohort-specific descriptions, not as evidence that one treatment is superior to another or that differences between the cohorts are caused by disease type. Details of the protocol's statistical plan are 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.

Before assignment: A total of 56 participants with ulcerative colitis (UC) or Crohn's disease (CD) were enrolled in the study. The results in this summary are based on the study's primary completion date (30 May 2025). The study is ongoing in the open-label period, and additional results will be reported upon study completion.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The FAS included all participants who received at least 1 dose of study drug.

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: The full analysis set (FAS) included all participants who received at least 1 dose of study drug. UC cohort and CD cohort were analyzed separately. Numbers in the total column are simply data from the two cohorts combined and not part of the results produced within the study.

6. Primary Endpoint

The registry lists the primary outcome as UC Cohort: Percentage of Participants With Clinical Response at Week 12 Based on Modified Mayo Score, measured over At Week 12.

The primary endpoint is the percentage of participants in the UC cohort with clinical response at Week 12, based on the modified Mayo score. The registry defines response as a reduction of at least 2 points and at least 25 percent in that score, together with either a decrease of at least 1 point in the rectal bleeding sub-score or a rectal bleeding sub-score of no more than 1 from baseline at Week 0.

The modified Mayo score combines stool frequency, rectal bleeding, and the Mayo endoscopic sub-score. Each component is graded from 0 to 3, and the total ranges from 0 to 9; higher scores indicate more severe disease. The endpoint therefore summarizes change across several aspects of UC disease activity while requiring a specified improvement in rectal bleeding.

A percentage is useful for describing how common the defined response was among the analysis population. Its confidence interval would convey uncertainty around that estimate. However, the registry record does not report the primary endpoint percentage or its 95% confidence interval, so the magnitude and precision of the study's primary result cannot be assessed from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is binary at the participant level: each participant either meets the stated clinical-response definition at Week 12 or does not. A percentage expresses the share meeting that definition. The registry identifies the endpoint as a percentage and specifies a 95% confidence interval as its dispersion measure, but does not post either the percentage or the interval.

What does a confidence interval convey?

In general, a confidence interval describes the statistical uncertainty around an estimate under the method used to calculate it. For a percentage, a wider interval indicates less precision than a narrower interval. It does not describe the range of individual participant outcomes, and it does not remove possible bias from study design, selection, outcome assessment, or missing data. Since no interval is reported for the primary endpoint, its precision cannot be judged from the registry record.

Why does the endpoint definition matter?

The response definition requires a specified reduction in the modified Mayo total score as well as improvement in rectal bleeding. A participant meeting only part of that definition would not meet the full endpoint as written. This rule gives the endpoint a clinically interpretable threshold, while also making the estimated percentage dependent on the exact scoring and assessment procedures. The record describes the score components and the threshold, but does not provide the primary endpoint result or further details on scoring implementation.

What can be concluded from this design?

General statistical interpretation depends on how participants were assigned and whether a valid comparator exists. Here, allocation is nonrandomized and the record does not describe a separate control group. The UC and CD cohorts are not treatment comparison groups, because they differ by underlying disease and both receive vedolizumab. A contrast between their outcome percentages, if reported, would not be a randomized estimate of treatment effect. The registry record does not report an adjusted comparative analysis.

Open-label conduct means participants and study staff are not masked to treatment assignment. Since the record describes a single study drug and no randomized comparator, masking is listed as none. General considerations include the possibility that awareness of treatment could influence reporting or assessment. This is a design consideration rather than evidence that such influence occurred in this study.

Why does over-dispersion matter in general?

For count outcomes, a statistical model may assume a particular relationship between the average count and its variability. Over-dispersion means the observed variability is greater than that assumption allows; ignoring it can make uncertainty estimates too small. The primary endpoint is a participant percentage, not a count-rate endpoint. The registry does not report an over-dispersion analysis or a model that would make such an adjustment relevant to the posted primary result.

How should planning calculations be read?

The stated planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of the observed effect. For time-to-event illustrations, the stated output is a total number of events; for other illustrations, it is participants per arm. These are planning assumptions, not a report of the study's own design justification, and the record does not report that justification. A sample-size illustration is not observed power. Because the registry does not report the primary effect estimate, the numerical basis for interpreting a calculation tied to that effect is absent from the record.

Analysis populations and statistical procedures also affect interpretation. The primary population is described as the FAS, including participants who received at least one dose of study drug. The record does not report details of the statistical model, covariate adjustment, handling of missing endpoint measurements, or sensitivity analyses. Those omissions prevent a fuller appraisal of how the endpoint estimate would be produced and how robust it might be.

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("UC Cohort: Vedolizumab 300 mg")
n      <- c(41)
events <- c(17)
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  UC Cohort: Vedolizumab 300 mg  41  17  41.5  26.3  57.9  27.8  56.6  27.7  56.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists eight outcome measures. It identifies the UC Week 12 clinical-response percentage based on the modified Mayo score as the primary outcome and lists secondary outcomes for clinical remission, mucosal healing, and corticosteroid-free remission in UC, as well as clinical remission, enhanced clinical response, and corticosteroid-free remission in CD. The record does not report results or analyses for these outcomes.

When multiple outcomes are tested, the chance of at least one apparently positive result can increase. General statistical practice may address this through a prespecified testing hierarchy or adjustment, but the registry record does not report whether any multiplicity strategy was planned or used. It also does not report a statistical analysis plan or interim analyses. No multiplicity-adjusted or unadjusted outcome findings are available in the record.

The primary population is described as the FAS, comprising all participants who received at least one dose of study drug. Further details about analysis populations for other outcomes are not reported in the registry record. The record does not state how missing Week 12 scores, withdrawals, or incomplete follow-up were handled, nor does it describe imputation, censoring rules, or sensitivity analyses. Missing-data methods can affect a percentage estimate when outcome status is unavailable; without those details, the possible influence cannot be evaluated.

The registry lists zero analyses. This means that analysis results are not posted in the record; it does not establish that no analyses were conducted outside the registry. The sample-size justification and the statistical analysis plan are not reported in 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: covid-19 (6.7%), crohn's disease (6.7%), gastroenteritis (6.7%), ileus (6.7%), liver abscess (6.7%).

The registry lists serious adverse events for the UC cohort of 41 participants at risk, with 3 affected, and for the CD cohort of 15 participants at risk, with 6 affected. It lists other adverse events for 41 participants at risk in the UC cohort, with 19 affected, and for 15 participants at risk in the CD cohort, with 14 affected. Deaths are listed as 0 in each cohort.

These figures are descriptive summaries within the study groups. The UC and CD groups are not randomized comparison arms, and the record does not provide a control group for estimating a comparative risk. The counts therefore should not be interpreted as proving that treatment caused or prevented any event. Differences between disease cohorts may reflect differences in the participants or their conditions, and are not a treatment comparison.

The serious-event terms listed are COVID-19, Crohn's disease, gastroenteritis, ileus, liver abscess, and sepsis, each at 6.7%. The record does not clarify whether participants experienced more than one listed term, so the terms should not be added together or treated as mutually exclusive. These summaries do not provide event timing, duration, outcome, or attribution in the information reported. The record's safety figures describe what was recorded; they do not by themselves establish a causal relationship.

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

This study is designed to describe outcomes after every-four-week IV vedolizumab in Japanese participants with moderate to severe UC or CD who had secondary loss of response during every-eight-week maintenance treatment. Its primary endpoint focuses specifically on Week 12 clinical response in the UC cohort. The registry supplies the endpoint definition and the analysis population, but does not report the endpoint result. Consequently, no statement about the observed response percentage or its precision can be supported by the registry record.

The record also does not post results for the listed secondary outcomes. It cannot establish from these entries whether participants met remission, mucosal-healing, or corticosteroid-free-remission criteria. The absence of posted outcomes is not evidence that no outcome occurred; it means the registry record does not report the results needed to evaluate them.

The design is nonrandomized and open-label, and no separate control group is described. Even if cohort outcomes were reported, they would be descriptions from participants receiving the study intervention rather than controlled estimates of what would have happened under another treatment strategy. The UC and CD cohorts should not be compared as though disease assignment were randomized.

The posted safety summaries include serious and other adverse events and list no deaths in either cohort. They are useful descriptions of events recorded in the study, but without a control group and without further context they do not quantify comparative risk or establish treatment causation. Event terms may also overlap at the participant level, which the record does not clarify.

Thus, the registry record describes the study question, intervention, endpoint, and selected safety counts, but does not provide the efficacy analyses required to answer the primary question. It also does not report the statistical plan, missing-data methods, multiplicity approach, or sample-size justification. Those gaps limit assessment of both the estimates and the methods that would support them.

14. Why This Trial Matters Statistically

This study raises a focused statistical question: how to describe a defined clinical-response percentage in a population receiving more frequent IV vedolizumab after secondary loss of response during every-eight-week maintenance. The primary outcome uses a composite score and a specified threshold, so its interpretation depends on both the score components and the accompanying rectal-bleeding requirement. Reporting the percentage together with its confidence interval would be important for understanding both the magnitude and precision of the result; neither is reported in the registry record.

The design also illustrates why an intervention study should not automatically be read as a comparative trial. Nonrandomized allocation, no masking, and no separate control group mean that the record does not offer a randomized estimate against another treatment strategy. The UC and CD cohorts answer distinct disease-specific descriptive questions rather than serving as interchangeable arms.

Safety summaries matter alongside efficacy outcomes, but counts without a control group do not identify comparative safety effects. The listed serious-event terms and cohort counts provide a record of events, while leaving causality and comparative risk unresolved.

Finally, a registry entry can define outcomes and study conduct without posting analyses. In this case, the endpoint definitions are informative, but the lack of outcome results, analysis details, and missing-data methods prevents assessment of the primary estimate. The distinction between a planned study question and a reported statistical result is central to interpreting this record.

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 for interpreting the study is that the registry record does not report the primary endpoint result or its confidence interval. Without those, neither the response percentage nor its statistical precision can be evaluated. Results for the listed secondary outcomes are also not reported, despite the registry listing eight outcome measures.

The nonrandomized, open-label design and absence of a separate control group constrain causal interpretation. The registry describes UC and CD cohorts receiving the same intervention, not like-for-like treatment groups. Any apparent difference between cohorts would be confounded by their distinct disease populations and would not establish a treatment effect.

The record describes treatment and follow-up pathways, including a Week 12 assessment and later follow-up, but does not report participant flow, the number analyzed for each outcome, or reasons for missing assessments. Missing-data handling and sensitivity analyses are not reported in the registry record. This makes it difficult to judge whether incomplete outcome data could affect the endpoint estimate.

The registry does not report the statistical analysis plan, multiplicity handling, interim analyses, or sample-size justification. The stated planning assumptions are not a substitute for the study's own design rationale. The record also does not provide detailed safety context such as event timing or attribution, and does not clarify possible overlap among serious-event terms. These limitations restrict interpretation of both efficacy and safety from the posted information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Intravenous Vedolizumab Administered Every 4 Weeks in Japanese Participants With Moderate to Severe Ulcerative Colitis or Crohn's Disease — NCT04738942.
• Registry record last updated 2026-06-15; status last verified 2026-05.
• Results first posted 2026-06-15.
• 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 describes an open-label, Phase 3, nonrandomized, parallel study sponsored by Takeda in Japan. It evaluates IV vedolizumab 300 mg every four weeks in participants with moderate to severe UC or CD who experienced secondary loss of response during every-eight-week maintenance treatment. Enrollment is listed as 56, and the status is active, not recruiting.

The primary outcome is Week 12 clinical response in the UC cohort based on the modified Mayo score. The primary analysis population includes participants who received at least one study-drug dose. The primary result and its 95% confidence interval are not reported in the registry record. The registry lists eight outcome measures and zero analyses.

Safety summaries list serious and other adverse events in both cohorts and 0 deaths in each. The record does not report a control-group comparison, detailed statistical methods, missing-data handling, multiplicity methods, or the sample-size justification.