Safety and Tolerability Of Allogeneic Mesenchymal Stromal Cells in Pediatric Inflammatory Bowel Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Tolerability Of Allogeneic Mesenchymal Stromal Cells in Pediatric Inflammatory Bowel Disease (NCT02150551), a na phase 1 study. The primary outcome is Number of Subjects Who Experience Serious Adverse Events, Adverse Events, and/or Early Treatment Discontinuations..

2. Clinical Question

The clinical question is exploratory rather than comparative. The study aimed to describe safety and tolerability in a population with inflammatory bowel disease, not to establish whether the cell intervention outperformed another treatment. The record also lists clinical response and improvement in laboratory tests reflecting systemic inflammation as secondary outcomes. Those aims do not replace the primary safety question, and the registry record does not report analyzable results for those outcomes.

3. Trial Design

This was a phase 1, single-group study of allogeneic bone marrow-derived mesenchymal stromal cells for inflammatory bowel disease. The registry lists the study as completed, with an enrollment of 1 participant. Allocation is listed as NA and masking as none. Since there was no control group, the design supports description of the participant's reported experience but not a randomized or controlled estimate of treatment effect.

The intended population was children and young adults with inflammatory bowel disease. The study description specifies pediatric Crohn's disease or ulcerative colitis that had not responded to conventional therapies. The registry record does not report further eligibility details or participant characteristics, so the participant's age, disease history, and other clinical features cannot be characterized from this record.

The intervention was donor-derived mesenchymal stromal cells given intravenously. The arm description specifies 1 x 106 cells/kg weekly for 4 consecutive weeks, with an additional 4 weeks available at the principal investigator's discretion. The primary-outcome description separately refers to weekly infusions for 8 weeks. These descriptions differ in how they present the planned treatment duration; the registry record does not clarify how the optional treatment period applied to the participant.

The primary outcome concerned the number of participants experiencing serious adverse events, adverse events, and/or early treatment discontinuations. Its stated timeframe was 45 days after the last infusion. The outcome description also mentions post-treatment assessment and additional follow-up visits over 2 years. The record says the participant enrolled on 6/7/2018 and withdrew on 09/05/2018 because of refusal to continue study follow-up visits. It does not report whether the planned treatment course or all scheduled assessments were completed.

4. Participant Flow and Accounting

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

Overall Study

Analysis population for the primary outcome, as defined in the registry: STOMP001 was enrolled in the study on 6/7/2018 and was withdrawn from the study 09/05/2018 due to refusal to continue the follow-up visits for the study. Due to patient's refusal to continue the study, there were no relative data to be analyzed.

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: STOMP001 was enrolled in the study on 6/7/2018 and was withdrawn from the study 09/05/2018 due to refusal to continue the follow-up visits for the study.

6. Primary Endpoint

The registry lists the primary outcome as Number of Subjects Who Experience Serious Adverse Events, Adverse Events, and/or Early Treatment Discontinuations., measured over 45 days after the last infusion.

The primary endpoint was a count of participants experiencing serious adverse events, adverse events, and/or early treatment discontinuations. The stated timeframe was 45 days after the last infusion. This endpoint was intended to describe safety and tolerability following administration of allogeneic bone marrow-derived stromal cells to children and young adults with inflammatory bowel disease.

A count endpoint records how many participants meet a defined event criterion; it does not by itself measure the severity, duration, or clinical course of each event. Combining serious events, other adverse events, and early discontinuations can capture several ways a treatment course might raise safety or tolerability concerns. However, those components are not interchangeable. A serious adverse event, a non-serious adverse event, and a discontinuation can have different meanings and should be read separately when component-level information is available.

Safety outcomes are appropriate in an early-phase study because they describe adverse experiences and treatment continuation rather than requiring a comparison of clinical benefit. In a single-group study, the endpoint can document events recorded during the study, but it cannot establish whether those events were caused by the intervention or occurred more often than they would under another treatment or without the intervention.

The registry record states that the participant refused further follow-up and that no relative data were available to analyze. Consequently, the intended primary endpoint has no analyzable result reported in the record. The adverse-event summary lists safety counts, but those entries do not supply the missing overall primary-outcome analysis or establish complete ascertainment across the stated follow-up period.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count endpoint tell the reader?

The primary outcome is expressed as a count of participants experiencing specified events or an early treatment discontinuation. A count is a direct descriptive measure: it records how many participants met the defined criterion. It does not explain how many separate events occurred if an individual could experience more than one event, and it does not describe the timing or severity of an event unless those features are separately reported.

For interpretation, the numerator and the population under observation both matter. A count without complete follow-up can miss events that would have been detected with continued assessment. The registry record says the participant refused further follow-up and that no relative data were available to analyze. It does not describe a complete analysis population or explain how the primary endpoint was handled after withdrawal. As a result, the event summary should not be treated as proof that all outcomes in the planned period were captured.

Why does the absence of a comparator matter?

In a single-group study, observed outcomes can be described, but there is no concurrent group to show what might have occurred under a different treatment or under usual care. General statistical principle: a treatment contrast requires outcomes under at least two comparison conditions. Without that contrast, observed events cannot establish that the intervention caused them, prevented them, or changed their frequency.

The study is also listed as unmasked. General statistical principle: masking can reduce the influence of expectations on some judgments and reporting, although it cannot eliminate all sources of bias. The registry does not describe blinded assessment. For this safety-focused study, it is particularly important to distinguish the act of recording an event from a conclusion about its cause.

How should uncertainty be understood?

General statistical principle: a confidence interval communicates uncertainty around an estimate, with a wider interval indicating less precision under the method used. A p-value, when reported, addresses how compatible data are with a specified statistical model and null hypothesis; it does not measure the probability that a treatment works. The registry record reports no analysis count and does not give inferential estimates for the primary outcome. It therefore offers no reported confidence interval or hypothesis test for that endpoint.

With sparse event data, estimates are inherently imprecise, and conventional approximations may perform poorly. General statistical principle: methods for common outcomes can behave differently when event counts are very small, so the choice of interval or model matters. No such method is identified for the primary endpoint in the registry record. The summary entries should consequently be read as counts and labels, not as a precise estimate of event frequency in a target population.

What do the planning illustrations represent?

The planning illustrations are described as calculations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For non-time-to-event outcomes, their quantities are participants per arm; time-to-event planning uses a total number of events. The stated effects to detect are fractions of the observed effect.

These assumptions describe a planning exercise, not the actual single-group design. Equal allocation between two arms does not match this study's listed design, which has no comparator. The illustrations are not observed power and do not show that the study had a particular chance of finding an effect. Sample-size calculations describe what a hypothetical study might require under specified assumptions; they do not add information to the unavailable primary-outcome analysis.

General statistical principle: power calculations depend on the effect size, variability or event frequency, significance threshold, allocation, and analysis method. If the observed effect is unstable or unavailable for the endpoint of interest, planning based on it may not represent a clinically meaningful target. The registry record does not report the trial's own sample-size justification, protocol assumptions, or a statistical analysis plan, so none should be inferred from the planning illustrations.

What can be concluded from the reported analysis status?

The registry lists 0 analyses and states that no relative data were available for analysis because the participant refused continued follow-up. That status is consequential: a planned endpoint and a reported endpoint are not the same thing. The existence of an endpoint definition does not mean its analysis was completed. Likewise, the presence of adverse-event summary entries does not establish that every planned assessment was performed or that all outcomes were captured through the stated follow-up.

General statistical principle: missing follow-up can create bias when the likelihood of remaining observed is related to health status, treatment tolerability, or the outcome itself. The record gives refusal to continue follow-up as the reason for withdrawal, but it does not provide enough information to determine whether the missingness was related to an adverse event or to another factor. No imputation method or sensitivity analysis is reported in the registry record. The appropriate interpretation is therefore limited to the recorded entries, with uncertainty about outcomes after follow-up ended.

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("Mesenchymal Stromal Cells (MSCs)")
n      <- c(1)
events <- c(1)
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  Mesenchymal Stromal Cells (MSCs)  1  1  100.0  2.5  100.0  20.7  100.0  15.8  98.7

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists the primary safety endpoint and two secondary outcomes: clinical response and improvement in laboratory tests reflecting systemic inflammation. It does not report a statistical plan for controlling multiplicity across these outcomes. Multiplicity arises when several outcomes or tests are examined; without a prespecified approach, the chance of a misleading positive result can increase. This is a general statistical concern, not a claim that such a finding occurred in this study. No analyses are listed for the outcomes.

The record reports withdrawal because the participant refused further follow-up visits and says there were no relative data to analyze for the primary outcome. It does not explain how missing outcome data were to be handled, whether any imputation or sensitivity analysis was planned, or how the analysis population was defined. These details are not reported in the registry record.

Withdrawal and missing follow-up are not merely administrative details. If outcomes after withdrawal differ from outcomes that would have been observed with continued follow-up, a complete-case summary could give a distorted picture. General statistical principle: the credibility of an analysis depends on understanding why data are missing and how the analysis accounts for that missingness. The reason for withdrawal is recorded, but the record does not establish the relationship between withdrawal and the participant's subsequent health outcomes.

The record's adverse-event counts remain useful as reported safety entries, but they do not resolve the absence of a documented primary-outcome analysis. No inferential approach, population definition, multiplicity adjustment, or missing-data method should be assumed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: worsening crohn's disease (100.0%).

The registry adverse-event summary lists 1 participant at risk and 1 participant with a serious adverse event. It also lists 1 participant at risk and 1 participant with another adverse event, and reports 0 deaths. The serious adverse-event term shown is Worsening Crohn's disease, with 100.0% reported for that term.

These figures are descriptive registry entries, not a comparison with another treatment. The 100.0% label should be understood as the registry's reported proportion for the listed serious-event term; it does not establish causation, severity beyond the serious-event classification, or risk in a broader population. The record does not provide event timing, duration, resolution, or a detailed causal assessment.

The serious and other adverse-event counts should not be added. The record does not clarify whether the categories overlap or whether they describe separate events. Nor does the adverse-event summary replace the planned primary endpoint analysis: the registry says no relative data were available to analyze after withdrawal from follow-up. These entries describe what the safety summary records, but they do not demonstrate complete surveillance through the planned assessment period.

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

The result supports a narrow description of the registry record: the study enrolled 1 participant, the participant withdrew from follow-up, and the adverse-event summary lists a serious adverse event, another adverse event, and no deaths. The serious-event term is reported as Worsening Crohn's disease. The registry states that no relative data were available to analyze for the primary outcome.

It does not establish the frequency of adverse events among children or young adults with inflammatory bowel disease. A single-group study with enrollment of 1 participant cannot provide a controlled estimate, and no comparison group is available to separate events that occurred during the study from events attributable to the intervention. The reported term does not by itself establish that the intervention caused the worsening.

The result also does not answer whether the intervention improved Crohn's disease, ulcerative colitis, or laboratory measures. Clinical response and laboratory improvement are listed as secondary outcomes, but their results are not reported in the registry record. The stated primary safety assessment was intended to extend beyond treatment, while the participant declined further follow-up. The record does not establish how much of the planned assessment was completed.

General statistical principle: absence of an analyzable result is not evidence that an outcome did or did not occur. It means the record does not support a conclusion on that outcome. Similarly, a descriptive event count should not be interpreted as a precise estimate when the observation is sparse and follow-up is incomplete. The limitations are about what can be concluded from the available record; they do not establish the intervention's biological effect or its performance in other settings.

The most defensible reading is that this early-phase study sought to characterize safety and tolerability, but the registry does not report a complete primary endpoint analysis. Its entries document a specific safety summary and withdrawal, while leaving comparative effects, broader event rates, and secondary outcome results unresolved.

14. Why This Trial Matters Statistically

This study is statistically instructive because its planned question and its available evidence are not the same. The primary endpoint was defined as a count of participants with serious adverse events, adverse events, and/or early discontinuations, with a stated assessment after the last infusion. Yet the registry says the participant refused further follow-up and that no relative data were available to analyze. This illustrates why endpoint definitions alone do not guarantee a usable endpoint result.

The single-group design also clarifies the distinction between description and comparison. A safety event can be recorded, but without a comparator the study cannot estimate how the event frequency differs from another treatment condition. A recorded event is not, by itself, proof of a treatment-caused event. These are important distinctions when reading early-phase research, where safety description may be the central aim.

The adverse-event entries further show why categories and denominators require careful reading. The registry reports serious and other adverse-event entries separately, but does not explain whether they overlap. Treating them as separate people or adding their counts would exceed what the record states. Likewise, a reported percentage attached to a serious-event term is not a population-level risk estimate.

Finally, planning calculations and trial evidence answer different questions. The planning assumptions describe a hypothetical two-arm calculation, whereas this study is listed as single-group and has no comparator. Those illustrations cannot substitute for analyzed outcomes or turn an incomplete record into evidence of efficacy. Keeping design, outcome reporting, and planning assumptions distinct is essential to interpreting this study accurately.

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 main limitation is the very limited enrollment: the registry reports 1 participant. This means the record cannot characterize the range of experiences among the intended population or provide a stable estimate of event frequency. The participant's refusal to continue follow-up further limits the primary safety assessment; the registry explicitly says there were no relative data to analyze.

There is no comparator group, and masking is listed as none. As a result, reported events cannot be interpreted against an alternative treatment condition, and causal attribution cannot be made from the design alone. The record does not report detailed event descriptions, timing, duration, resolution, or a causal assessment for the serious adverse event.

The planned treatment duration is described in two ways: the arm description gives 4 consecutive weekly infusions with an option for an additional 4 weeks, while the primary-outcome description refers to weekly infusions for 8 weeks. The record does not clarify how the optional extension was applied. It also does not report whether the participant completed the intended treatment course.

The registry does not report participant characteristics beyond the broad intended population, nor does it provide a statistical analysis plan, sample-size justification, missing-data method, or multiplicity approach. The secondary outcome results are not reported in the registry record. These omissions limit both clinical interpretation and statistical assessment of how the study was intended to analyze outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Tolerability Of Allogeneic Mesenchymal Stromal Cells in Pediatric Inflammatory Bowel Disease — NCT02150551.
• Registry record last updated 2024-05-06; status last verified 2024-04.
• Results first posted 2023-01-20.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry describes a completed phase 1, single-group study of allogeneic bone marrow-derived mesenchymal stromal cells for pediatric inflammatory bowel disease. Enrollment was 1, with no comparator and no masking. The primary outcome concerned serious adverse events, adverse events, and/or early treatment discontinuations, assessed 45 days after the last infusion.

The participant enrolled on 6/7/2018 and withdrew on 09/05/2018 because of refusal to continue follow-up visits. The registry states that no relative data were available to analyze for the primary outcome. The safety summary lists 1 participant with a serious adverse event, 1 with another adverse event, and 0 deaths; Worsening Crohn's disease is the reported serious-event term at 100.0%. Secondary outcomes concern clinical response and laboratory improvement, but results are not reported in the registry record.