Donor-Derived Viral Specific T-cells (VSTs) for Prophylaxis Against Viral Infections After Allogeneic Stem Cell Transplant: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Donor-Derived Viral Specific T-cells (VSTs) for Prophylaxis Against Viral Infections After Allogeneic Stem Cell Transplant (NCT03883906), a na phase 2 study. The primary outcome is Number of Participants With Presence of a Toxicity.

2. Clinical Question

As general context, a prophylaxis study asks whether an intervention can be used to prevent an event rather than only treating it after it occurs. The registry also lists presence of a viral infection as a secondary outcome, which relates directly to the prevention question. However, the record does not provide a reported result for that outcome. It also does not specify which viruses were counted, how infection was defined, or how follow-up for that outcome was handled. The available registry information therefore establishes the study question and broad design, but does not allow a quantitative assessment of the prevention outcome.

3. Trial Design

The registry describes a completed phase 2 study with a single-group model and no masking. Enrollment is listed as 30. The intervention is viral-specific T-cells (VSTs), and the study concerns their use after allogeneic stem cell transplant. The sponsor is Children's Hospital Medical Center, Cincinnati. The listed start date is 2019-03-16, and the primary completion date is 2020-10-31.

A single-group design means outcomes are recorded for participants receiving the intervention without a registry-described control arm. Allocation is listed as not applicable, and masking is listed as none. The record therefore does not describe random assignment or blinded outcome assessment. With no comparator described, outcomes cannot be directly contrasted with outcomes under another assigned strategy within this study.

The primary outcome is the number of participants with a toxicity over 30 days. The registry lists presence of a viral infection as a secondary outcome. It also states that there are 3 outcome measures, but the record does not give full details for all of them. It lists no analyses. The population field for the primary outcome is blank, and details of the analysis population are not reported in the registry record.

The registry record does not report the recruitment process, eligibility criteria, the VST administration schedule, participant characteristics, or the duration of follow-up for outcomes other than the primary outcome. It also does not report a statistical analysis plan or a sample-size justification. General considerations for interpreting a single-group study include the possibility that outcome rates reflect both the intervention and other features of the participants, transplant care, or follow-up. Without a comparator and fuller outcome reporting, those influences cannot be separated using this 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.

Overall Study

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Presence of a Toxicity, measured over 30 days.

The primary endpoint is the number of participants with a toxicity during 30 days. The registry describes the measure as a count of participants and says that participants will be assessed for the presence of a toxicity. This is a participant-level occurrence measure: it concerns whether a participant experienced a toxicity, rather than the total number of separate toxicity events.

As general context, a defined safety endpoint is used to make the observation period and type of outcome explicit. Recording whether participants experience toxicity can describe the safety experience during the specified timeframe. It does not, by itself, establish that an intervention caused an event. In a single-group study, the endpoint does not provide a direct comparison with an alternative treatment or with no intervention.

The registry record does not name the toxicities included, give a severity grading system, explain how events were attributed, or define the analysis population. Although the primary outcome and timeframe are stated, the observed result is not reported in the registry record. The record therefore does not show how many participants met the endpoint or how precisely any estimated event frequency is known. The secondary outcome concerning presence of a viral infection is distinct from this toxicity endpoint and should not be treated as its substitute.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Design and comparison. The registry describes a single-group study with no masking and no applicable allocation. As general statistical context, a single-group design estimates outcomes in the group studied; it does not estimate a between-group contrast unless another comparison source is defined. A randomized comparison can help separate treatment effects from differences in participants and care, while a single-group study cannot make that separation on its own. No comparator is described in the registry record.

Outcome type. The primary endpoint is a count of participants with a toxicity during 30 days. In general, a binary participant-level outcome records whether each participant had the event or did not have it. The resulting count depends on the number of participants whose outcome status is known. To interpret an event frequency, readers need both the event count and the relevant denominator. The registry record reports neither the primary count nor its denominator.

Precision and uncertainty. In general, an effect estimate is a numerical summary of the observed outcome, and a confidence interval describes the uncertainty around that estimate under a statistical model. Precision depends on the amount of information available and on the outcome’s variability. A confidence interval is not a guarantee that the true value lies within its endpoints, and it does not correct for bias, missing data, or a lack of a comparator. No estimate or confidence interval for the primary endpoint is reported in the registry record.

Inference and interpretation. In general, a hypothesis test evaluates how compatible observed data are with a stated null hypothesis under assumptions. A p-value is not the probability that a treatment is effective, and it does not measure the size or importance of an effect. A test in a single-group study would not overcome the absence of a concurrent comparator. The registry record lists no analyses and reports no p-value or inferential model for the outcomes.

Planning versus observed evidence. A sample-size calculation is a planning exercise based on assumptions about an effect, variability, allocation, and an error rate. Such a calculation does not describe the observed data or establish that an analysis had a particular probability of detecting an effect. General sample-size illustrations should therefore be interpreted as planning scenarios, not as observed power. The registry record does not report its own sample-size justification or statistical plan.

Events and safety categories. Adverse-event counts can be summarized by participants affected, event occurrences, severity, seriousness, and attribution. These are not interchangeable summaries. One participant may have more than one event, and an event may be recorded without a determination that it was caused by the intervention. As general context, interpreting safety counts requires clear event definitions, observation periods, denominators, and rules for attribution. The registry record gives some counts but does not explain all these details.

Multiplicity. When several outcomes or statistical tests are considered, the chance of at least one false-positive finding can increase if each is tested separately at a chosen error rate. General approaches include identifying a primary outcome in advance, adjusting for multiple tests, or treating secondary analyses as exploratory. The registry identifies a primary outcome and lists a viral infection outcome as secondary, but does not report whether any multiplicity strategy was planned or used. It lists 3 outcome measures and no analyses.

Missingness and analysis population. In general, missing outcome information can affect estimates, especially if the reasons for missingness are related to the event or intervention. Analysis populations also determine which participants contribute to an estimate. The registry does not report missing-data methods, outcome-specific denominators, or a defined analysis population. These gaps prevent assessment of whether all enrolled participants contributed to each outcome and how incomplete information was handled.

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("Viral Specific T-cells (VSTs)")
n      <- c(23)
events <- c(0)
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  Viral Specific T-cells (VSTs)  23  0  0.0  0.0  14.8  0.0  14.3  0.1  14.2

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary toxicity outcome and lists presence of a viral infection as a secondary outcome. It states that there are 3 outcome measures, while the record does not give full descriptions for all of them. It lists no analyses. The registry record does not report whether a multiplicity adjustment, a testing hierarchy, or another strategy for interpreting multiple outcomes was planned or used.

As general context, testing several outcomes can increase the chance of finding an apparently notable result by chance if each is considered independently. Naming a primary outcome can help distinguish the main question from secondary questions, but it does not reveal how results were analyzed. Since no outcome analysis results are reported, multiplicity cannot be evaluated from this record.

Missing-data handling is not reported in the registry record. The primary outcome population field is blank, and outcome-specific denominators are not given. The record therefore does not establish how many participants had an evaluable outcome, whether follow-up was complete, or how missing outcome status was treated. These details are necessary to assess the population represented by any estimate and the potential influence of incomplete observation.

General statistical practice distinguishes the population enrolled from the population included in a particular analysis. Different analysis populations can yield different estimates, especially when exclusions or missing observations are related to outcomes. The record does not describe an analysis population or methods for handling exclusions. It is therefore not possible to assess these aspects of the study’s reported analyses.

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 non-serious adverse event terms

The registry adverse-event entry lists the VST group with 23 participants at risk for serious adverse events and 0 affected. For other adverse events, it lists 23 at risk and 1 affected. It also lists 2 deaths. These are registry safety figures; they are not a comparison against another group.

The record does not provide event descriptions among the serious-event terms, and it does not explain whether the other adverse event or deaths were related to the intervention. It also does not clarify the relationship between deaths and the adverse-event categories, whether events overlapped, or how the safety observation period was defined. The figures should not be combined or interpreted as evidence of causation.

As general context, “at risk” denominators indicate the group considered for a safety category, while “affected” counts indicate participants recorded with an event in that category. Safety summaries are most informative when accompanied by definitions, timing, severity, attribution, and completeness of follow-up. Those details are not reported in the registry record. The primary toxicity endpoint is a separate registered measure; the listed safety figures do not supply its unreported result.

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

The registry record describes a completed phase 2, single-group study of donor-derived VSTs after allogeneic stem cell transplant. It identifies toxicity during 30 days as the primary outcome and presence of a viral infection as a secondary outcome. These details establish the general question being studied and the broad design used to investigate it.

The record does not report the primary outcome result or a result for the viral infection outcome. It also does not provide an effect estimate, confidence interval, or statistical test. Therefore, the registry information does not establish the observed frequency of either outcome or the precision of an estimate. The safety counts give limited event information, but the record does not provide enough detail to connect those counts to the primary endpoint or to establish causality.

As general context, an outcome observed in a single group can describe what happened among participants followed in that group. It cannot, by itself, show what would have happened under a different treatment or no intervention. Differences in participant characteristics, transplant care, and follow-up can all affect observed outcomes. A comparator and sufficiently detailed outcome reporting are needed for a stronger comparative interpretation.

The registry record therefore does not support a conclusion that VSTs prevent viral infection or do not prevent it, nor does it establish that VSTs cause or do not cause toxicity. Those are not conclusions that can be drawn from the available outcome and design information. The appropriate interpretation is limited to the registered study purpose, design, and the safety counts as reported, with the primary and secondary outcome results not reported in the registry record.

14. Why This Trial Matters Statistically

This study raises a clinically relevant statistical question: how to describe toxicity and viral infection outcomes when donor-derived VSTs are used after allogeneic stem cell transplant. The registry identifies both an adverse outcome measure and a prevention-related secondary outcome. Keeping these outcomes distinct matters because a safety endpoint and an infection endpoint answer different questions.

The single-group design also illustrates an important distinction between describing outcomes and estimating comparative effects. A study can document events among people who received an intervention, but without a comparator it cannot show how those outcomes differ from an alternative strategy. This is especially important when outcomes may also be influenced by the underlying transplant context and follow-up.

Outcome definitions and analysis details are essential for interpreting counts. A participant-level toxicity count needs a clear definition and denominator; safety interpretation also depends on event timing, severity, and attribution. The registry record does not report these details fully or provide results for the primary and secondary outcomes. The missing information limits what can be learned from the record about precision, completeness, and the relationship between the intervention and observed events.

As general statistical context, transparent reporting of outcome results, analysis populations, missing-data methods, and uncertainty allows readers to distinguish a descriptive observation from a supported comparison. This record makes the study’s broad design and questions visible, while also showing why outcome results and analysis details are necessary before drawing stronger conclusions.

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 does not report the primary toxicity result, the viral infection result, or estimates of uncertainty. It also lists no analyses. This prevents quantitative evaluation of the registered outcomes and their precision.

The study is single-group, with no comparator described and no masking. These design features limit comparative and causal interpretation. The record does not report eligibility criteria, participant characteristics, or detailed follow-up information, so the population represented and the context for observed outcomes cannot be fully assessed.

The primary endpoint is described broadly as presence of a toxicity during 30 days. The registry does not specify the toxicity types, severity definitions, attribution rules, or outcome denominator. It does not provide full descriptions for all 3 outcome measures. The analysis population and missing-data handling are also not reported in the registry record.

The safety entry lists counts for serious events, other events, and deaths, but provides limited context for interpreting them. Event details, attribution, overlap, and the relationship of the counts to the primary endpoint are not explained. The record also does not report its statistical analysis plan, multiplicity approach, or sample-size justification. These limitations restrict assessment of both the safety information and the study’s capacity to answer its prevention question.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Donor-Derived Viral Specific T-cells (VSTs) for Prophylaxis Against Viral Infections After Allogeneic Stem Cell Transplant — NCT03883906.
• Registry record last updated 2022-12-13; status last verified 2022-11.
• Results first posted 2022-12-13.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed phase 2, single-group study of viral-specific T-cells for prophylaxis after allogeneic stem cell transplant. Masking is listed as none, and enrollment is listed as 30. The sponsor is Children's Hospital Medical Center, Cincinnati. The start date is 2019-03-16, and primary completion is dated 2020-10-31.

The primary outcome is the number of participants with toxicity during 30 days. Presence of a viral infection is listed as a secondary outcome. The record lists 3 outcome measures and no analyses. It does not report the primary or secondary outcome results, the analysis population, or missing-data methods.

The adverse-event entry lists 0 affected for serious adverse events, 1 affected for other adverse events, and 2 deaths. The record does not establish causal attribution for these figures. Its single-group design and unreported outcome analyses limit comparative interpretation.