An Extension Study to Evaluate the Long-Term Safety and Tolerability of UTTR1147A in 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 An Extension Study to Evaluate the Long-Term Safety and Tolerability of UTTR1147A in Participants With Moderate to Severe Ulcerative Colitis or Crohn's Disease (NCT03650413), a na phase 2 study. The primary outcome is Number of Participants With Adverse Events.

2. Clinical Question

The central question is about long-term safety and tolerability, not whether UTTR1147A is more effective than another treatment. The primary outcome is the number of participants with adverse events. The posted safety summary reports 9 participants with serious adverse events and 52 with other adverse events, each among 128 participants at risk. These are descriptive counts from a single-group extension study.

Because participants were not randomized between UTTR1147A and a concurrent control, the record cannot establish how those counts would compare with outcomes under another treatment or under observation. The treatment and observation arrangement described in the protocol depended on disease status, so it does not create a randomized comparison. The record also does not report the reason for termination or a causal analysis separating events related to treatment from events arising for other reasons. The findings therefore address what was recorded in this study, rather than a comparative treatment effect.

3. Trial Design

This was a Phase II, open-label extension study of UTTR1147A in participants with moderate to severe ulcerative colitis or Crohn's disease. The study used a single-group model, with no masking and no randomized allocation. Its stated purpose was to evaluate long-term safety and tolerability. The registry record describes enrollment from parent studies GA29469 and GA39925 and lists enrollment of 143.

The study began on 2019-01-14, reached its primary completion date on 2022-07-12, and has a status of terminated. The registry record does not report why the study was terminated. Its brief description says that participants would have the opportunity to receive UTTR1147A until clinical remission was achieved, while the arm description says treatment or observation depended on disease status. The safety population description adds that treatment was available to participants if they lost remission. These descriptions do not indicate random assignment to treatment or observation.

The primary outcome listed is the number of participants with adverse events, with a timeframe of up to 2 years. The safety-evaluable population comprised 128 patients who received at least one dose of study drug. That population is the denominator for the posted safety counts, rather than the enrollment figure. The registry record does not report a participant flow accounting for the difference between enrollment and the safety-evaluable population, or a separate analysis population for effectiveness outcomes.

As an extension study, the design focuses on safety observations during continued follow-up. Its open-label, single-group structure can describe event counts among treated participants, but cannot by itself distinguish treatment effects from background disease, other care, or other factors. The registry record does not report a concurrent control group or a comparative treatment analysis.

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: This is a single-arm open-label extension study. There is only one arm.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The safety-evaluable population comprised 128 patients who received at least one dose of the study drug. There was only 1 arm in this open label extension study. Treatment was available to all study participants if they lost remission.

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: There was only 1 arm in this study. The protocol was written with this single group receiving treatment based upon remission status.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Adverse Events, measured over Up to 2 years.

The primary endpoint is the number of participants with adverse events. The outcome is defined as a count of participants with an event, rather than a count of every event episode. Its stated timeframe is up to 2 years, and severity was determined according to the National Cancer Institute Common Terminology Criteria for Adverse Events, Version 4.0 (NCI CTCAE v4.0).

Safety endpoints of this kind are used to describe how many participants experienced events during follow-up. A participant-based count can communicate the reach of an event across the study population, but it does not by itself show how often an individual experienced recurrent events, how long events lasted, or the full range of severity. The registry record does not describe whether recurrent events were handled in any particular way for the primary endpoint.

The posted safety figures distinguish serious adverse events from other adverse events. They report 9 participants with serious adverse events and 52 with other adverse events among 128 at risk. These categories should be read as separate reported summaries, not as a comparative estimate of treatment effect. The record does not provide a statistical analysis for the primary outcome, an uncertainty interval, or an adjusted estimate.

In general, an endpoint based on adverse events is useful for a safety-focused study because it directly records reported harms during follow-up. Its interpretation still depends on how events were collected, classified, and attributed. Details of event ascertainment and attribution are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a Phase II, open-label, single-group extension study and lists one outcome measure, the number of participants with adverse events. It lists no statistical analyses. That distinction is important: an outcome definition says what is being measured, while an analysis plan explains how the measurement will be summarized or compared. The record gives a descriptive safety summary but does not list a statistical model, an inferential test, or an adjustment strategy.

What does a participant count represent?

The primary outcome is a count of participants who experienced an adverse event. In general, a participant-based count indicates how many people in the analysis population had an event during the stated timeframe. It does not equal the total number of event episodes if an individual can experience an event more than once. The registry record does not report how recurrent events were treated in the primary endpoint or provide event-level data for examining recurrence.

The safety-evaluable population is defined as patients who received at least one dose, and it comprised 128 patients. The serious and other adverse-event figures are each reported with 128 at risk. The enrollment figure is 143. These figures refer to different aspects of the study record; the registry does not provide a participant disposition explaining who was excluded from the safety population or why.

Why does the design limit comparative inference?

General statistical context: a randomized comparator can help distinguish an intervention's effect from differences that arise through participant characteristics, disease course, or other influences. This study is listed as single-group, open-label, and without randomized allocation. Consequently, its safety counts describe events in the study group but do not estimate how those participants would have fared under a concurrent alternative. Observation based on disease status is not equivalent to random assignment, and the record does not report a controlled comparison.

Without a comparative design, a difference between this group's observed experience and an outside expectation cannot be attributed to UTTR1147A from the registry results alone. Even when a count seems clinically important, its interpretation requires context about the population, follow-up, event ascertainment, and background event rates. The registry record does not report an external benchmark or comparative analysis.

What would uncertainty estimates add?

General statistical context: a confidence interval describes a range of values compatible with an estimate under a specified statistical procedure and its assumptions. It communicates sampling uncertainty, not every source of uncertainty. An interval around a single-group event estimate would not correct for the absence of a control group, incomplete outcome ascertainment, or potential influences of open-label assessment.

No confidence interval or other inferential estimate is listed for the adverse-event counts, and the record lists no analysis entries. The counts therefore should be read as posted summaries rather than as precise estimates of risk for a wider population. The registry record does not report a statistical method for accounting for follow-up time or differences in duration of observation. The stated timeframe is up to 2 years; that wording does not establish that every participant was observed for the same duration.

How should the listed planning assumptions be understood?

General statistical context: sample-size calculations are planning exercises that depend on assumptions about the effect to detect, the significance level, allocation, and statistical method. The registry's planning description specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect expressed as a stated fraction of an observed effect. It also distinguishes total events for time-to-event calculations from participants per arm for other calculations.

Those assumptions do not change the actual study design. This study is not a randomized two-arm comparison, and its registry record lists no statistical analyses. Planning illustrations are not observed power and do not turn single-group safety counts into a controlled treatment effect. A sample-size calculation also cannot establish that the study had adequate precision for an endpoint unless the relevant assumptions and analysis correspond to the study question and design.

General statistical context: over-dispersion refers to variability greater than a statistical model expects. It can matter for some count outcomes, but the primary outcome is defined as participants with an event, and the registry record does not report a model or an over-dispersion assessment. There is no basis in the record to say that such a model was used or needed. More broadly, the registry provides no detailed statistical analysis plan, model specification, or method for handling incomplete outcome data.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure, the number of participants with adverse events, and no statistical analyses. It does not report a multiplicity adjustment or explain how multiple hypotheses, outcome definitions, or event categories would be handled. The serious and other adverse-event summaries and the listed serious-event terms are descriptive entries; no testing strategy is reported for them. Without a stated inferential plan, the presence of several event categories should not be read as a series of confirmed statistical findings.

The safety-evaluable population comprised 128 patients who received at least one dose. Enrollment is listed as 143. The registry record does not report the reasons participants were not included in the safety-evaluable population, the amount or pattern of missing outcome data, or a method for handling missing data. It also does not report whether all participants had the same observation duration. The outcome timeframe is up to 2 years, which does not itself establish equal follow-up.

For safety interpretation, the defined population matters because event counts depend on who was followed and how events were captured. The record does not describe a missing-data sensitivity analysis or a separate analysis population. It also does not provide a participant flow that would explain how enrollment translated into the safety population. These omissions limit assessment of completeness and make it inappropriate to assume that missingness had no effect.

General statistical context: multiplicity procedures are used to control the risk of false positive conclusions when a study tests multiple hypotheses. Missing-data methods address outcomes that are unavailable for some participants, but their suitability depends on why data are missing and on the analysis objective. The registry record does not report procedures in either area; no particular approach should be inferred.

11. 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: lipase increased (2.3%), colitis ulcerative (1.6%), amylase increased (1.6%), anaemia (0.8%), arteriosclerosis coronary artery (0.8%).

The posted safety summary is for the UTTR1147A 60 group. It lists 128 participants at risk for serious adverse events and 9 participants with serious adverse events. For other adverse events, it also lists 128 at risk and 52 affected. The summary lists 0 deaths. These are participant counts, not a comparison between treatment groups.

The serious-event terms are reported separately, with Lipase increased at 2.3%, Colitis ulcerative at 1.6%, Amylase increased at 1.6%, and Anaemia, Arteriosclerosis coronary artery, and Cataract each at 0.8%. The terms and percentages describe the registry's listed serious-event entries; they should not be treated as a ranking of overall treatment risk or as evidence of causation. The record does not describe a causal attribution analysis.

General statistical context: adverse-event counts are affected by the length and completeness of follow-up, event definitions, and reporting practices. The timeframe is up to 2 years, but the record does not establish equal observation time for every participant. The open-label single-group design also means there is no randomized control against which to judge whether these counts are higher or lower than they would otherwise have been.

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

The results establish that adverse events were recorded among participants in the safety-evaluable population during an extension study of UTTR1147A. Specifically, the posted summary lists 9 participants with serious adverse events and 52 with other adverse events among 128 at risk, and 0 deaths. It also lists several serious-event terms with their recorded percentages. These are descriptive observations from the registry record.

They do not establish that UTTR1147A caused or did not cause any particular event. The study had no randomized comparator, was open-label, and used a single-group model. The record does not report a comparative analysis, causal attribution, or statistical uncertainty estimate for the counts. It is therefore not possible to use these figures alone to estimate how the safety experience differs from another treatment or from observation under comparable conditions.

The findings also do not answer an effectiveness question. Although the study description refers to clinical remission and treatment availability depending on disease status, the listed primary outcome is adverse events. No effectiveness outcome analysis is listed. The study status is terminated, but the reason for termination is not reported in the registry record; that status does not identify the cause or imply a particular safety conclusion.

General statistical context: a study result is most informative when interpreted alongside its design, population, endpoint definitions, completeness of follow-up, and uncertainty. Here, the counts are tied to a safety-evaluable population of 128 patients who received at least one dose, while enrollment is listed as 143. The record does not explain the participant disposition between those figures or report how missing data were handled. These features limit how broadly the results can be interpreted.

The appropriate conclusion is narrow: the registry reports the stated adverse-event counts in this open-label extension study. The counts neither demonstrate comparative safety nor establish that treatment was responsible for, or unrelated to, the events.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of the difference between safety description and comparative inference. Its primary outcome counts participants with adverse events, and the registry reports serious and other adverse-event counts in a safety-evaluable population. Such summaries can describe what was observed during follow-up, which is relevant to a study whose stated purpose is long-term safety and tolerability.

At the same time, the single-group, open-label structure sets a clear boundary on the conclusions. Without random allocation to a concurrent comparator, there is no direct estimate of how event counts would differ under another treatment or under observation. This is not a flaw in the meaning of a descriptive safety summary; it is a limitation on the question that the design can answer.

The distinction between enrollment and the safety population also matters. Enrollment is listed as 143, while the safety-evaluable population comprises 128 patients who received at least one dose. The record does not explain the participant disposition between those figures. Clear accounting of analysis populations is important because readers need to know which participants contribute to each outcome summary.

The record also illustrates why statistical analysis details matter. No statistical analyses are listed, and no uncertainty estimates are reported for the adverse-event counts. Descriptive counts remain useful, but they do not quantify sampling precision or resolve the possible effects of open-label event assessment, differing follow-up, and missing data. The record does not report methods addressing these issues.

Finally, the terminated status should be separated from the numerical safety results. Since the reason for termination is not reported, it cannot be used as evidence for a particular interpretation of the adverse events. The statistical value of the record lies in documenting the study structure and its posted safety observations while making the limits of inference explicit.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation is the absence of a randomized comparator. The study is open-label and single-group, so its adverse-event counts describe the participants in the extension but do not estimate a comparative difference. The registry description says that treatment or observation depended on disease status; that arrangement does not provide a like-for-like control group.

The safety-evaluable population comprised 128 patients who received at least one dose, while enrollment is listed as 143. The registry record does not explain the disposition between these figures or report whether outcome information was complete for all participants in the safety population. It does not describe missing-data handling or provide a participant flow.

Follow-up is stated as up to 2 years. The record does not report how long each participant was observed, whether follow-up time varied, or whether the analysis accounted for such variation. A participant count without those details cannot show the timing or duration of events. The record also does not describe how recurrent events were handled for the primary endpoint.

No statistical analyses are listed. The record does not provide confidence intervals, a comparative model, an analysis of event attribution, or a multiplicity strategy. It therefore offers limited information about precision, causes, or the robustness of the descriptive summaries. The open-label design may also affect event reporting or assessment; this is a general design concern, not a finding established by the record.

The status is terminated, but the reason is not reported in the registry record. It cannot be inferred from the status whether termination was connected with safety, recruitment, or another consideration. These limitations are specific to the available design and reporting details and constrain interpretation of the posted counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: An Extension Study to Evaluate the Long-Term Safety and Tolerability of UTTR1147A in Participants With Moderate to Severe Ulcerative Colitis or Crohn's Disease — NCT03650413.
• Registry record last updated 2023-09-29; status last verified 2023-09.
• Results first posted 2023-09-29.
• 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.

18. Record Summary

This Phase II study evaluated the long-term safety and tolerability of UTTR1147A in participants with moderate to severe ulcerative colitis or Crohn's disease. It was an open-label, single-group extension study with no randomized allocation. The registry lists enrollment of 143 and a safety-evaluable population of 128 patients who received at least one dose.

The primary outcome was the number of participants with adverse events over a timeframe of up to 2 years, with severity determined according to NCI CTCAE v4.0. The posted safety summary lists 9 participants with serious adverse events, 52 with other adverse events, and 0 deaths among 128 at risk. The record lists no statistical analyses.

The study began on 2019-01-14, had a primary completion date of 2022-07-12, and is marked terminated. The reason for termination, participant disposition, missing-data methods, and comparative analyses are not reported in the registry record. The counts are descriptive and do not establish a comparative treatment effect or causal attribution.