Ex Vivo TCR αβ T Cell Depletion for Graft-Versus-Host Disease Prophylaxis in Mismatched Donor Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ex Vivo TCR αβ T Cell Depletion for Graft-Versus-Host Disease Prophylaxis in Mismatched Donor Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies (NCT03717480), a na phase 2 study. The primary outcome is Number of Participants With Severe Acute GVHD-free Survival.

2. Clinical Question

The clinical question concerns a transplant-prevention strategy and a short-term clinical outcome. The registry describes removing a subset of donor white blood cells before transplantation. The primary outcome is the number of participants with severe acute graft-versus-host disease-free survival at 100 days post-SCT. This is a count, not a reported comparison of outcome rates between treatment groups.

The study also lists secondary outcomes addressing acute and chronic GVHD, GVHD and relapse-free survival, immunosuppression-free survival, hematologic recovery, immune reconstitution, disease relapse, and transplant-related mortality. These outcomes cover several aspects of post-transplant experience, but the record does not report their results or analysis details. The registry lists 12 outcome measures in total.

Because the study has a single group and no like-for-like control group, the primary question is descriptive in the available record. It cannot, from the registry information alone, establish how outcomes compare with another prophylaxis strategy or with outcomes that would have occurred without the intervention.

3. Trial Design

The registry identifies this as a Phase 2 study with a single-group model. Allocation is recorded as NA, and masking is recorded as none. The title and study description concern ex vivo TCR αβ T-cell depletion for GVHD prophylaxis in mismatched-donor peripheral blood stem cell transplantation for hematologic malignancies. Dana-Farber Cancer Institute is listed as sponsor.

The intervention description says the stem cell apheresis product is depleted of TCRαβ T cells by negative selection using an automated CliniMACS® Plus device. It also states that CD34+ stem cell counts are obtained before and after processing with the CliniMACS device. The brief description identifies the CliniMACS® TCR α/β Reagent System. These details describe the intervention process; they do not establish the amount of depletion achieved or any clinical outcome.

Enrollment is 2. The record lists a start date of 2020-01-21 and primary completion on 2021-04-26, and gives the study status as terminated. A reason for termination is not reported in the registry record. The record does not describe a control group, random assignment, or masking, so the study should not be read as a randomized comparison.

The primary outcome is the number of participants with severe acute GVHD-free survival, assessed at 100 days post-SCT. Several secondary outcomes are listed, but the registry record does not report results for them. It also records zero analyses. The protocol, recruitment details, eligibility criteria, follow-up completeness, and analysis population are not reported in the registry record.

For a single-group study, observed outcomes can describe what happened among enrolled participants, if those outcomes and denominators are reported. Without a concurrent comparison group, differences from other studies or expected outcomes may reflect differences in patient characteristics, transplant procedures, follow-up, or other factors. The record does not provide enough information to evaluate those potential influences.

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.

Population: Only evaluable participants, defined as participants who received investigational product, are included in the analysis population. Therefore, participants who never started protocol treatment have been excluded.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Severe Acute GVHD-free Survival, measured over 100 Days.

The primary endpoint is the number of participants with severe acute GVHD-free survival at 100 days post-SCT. It is expressed as a participant count. The registry description says the count will be assessed at 100 days after stem cell transplantation. The record does not provide a posted count or define the precise event and censoring rules used to classify a participant as having severe acute GVHD-free survival.

As a general statistical concept, a composite or event-free outcome can summarize whether participants remain free of a specified adverse event over a defined follow-up period. Such an endpoint may be useful in transplant research because it focuses on a clinically relevant outcome during a stated period. Interpretation depends on a clear definition of the event, the handling of death and incomplete follow-up, and consistent outcome assessment. Those details are not reported in the registry record.

A count alone is not a rate unless its denominator and observation context are clear. Nor does a count show how precisely an outcome frequency has been estimated. To assess uncertainty, readers would need the observed outcome count, the number of participants assessed, and an appropriate estimate of uncertainty. The registry record does not report the primary endpoint result or an interval estimate. Therefore, the endpoint’s stated purpose can be described, but its observed value and precision cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group study estimate?

A single-group study observes outcomes among participants receiving the study intervention, without a concurrent control group. If results are reported, the group’s observed outcome can be described. The design does not directly estimate what would have happened to the same participants under a different intervention. This distinction matters because the outcome may also reflect participant characteristics, transplant care, follow-up practices, or other influences.

Here, the registry lists a single-group model, allocation as NA, and masking as none. A randomized comparison is not described. The registry record also does not report an outcome analysis, so no group estimate can be interpreted from the posted information.

What does a participant count tell a reader?

The primary outcome is a count of participants meeting the stated severe acute GVHD-free survival outcome at 100 days post-SCT. A count is a descriptive quantity. To interpret it as an outcome frequency, readers need to know how many participants were assessed and how incomplete follow-up was handled. To assess precision, they need an uncertainty estimate based on the observed data and a stated method. Neither the primary count nor its uncertainty is reported in the registry record.

In general, confidence intervals express a range of values compatible with the data under a statistical model and method. A wide interval indicates that the data are consistent with a broader range of values; a narrow interval indicates greater precision under that method. An interval does not remove design limitations, and it cannot create a control comparison where none exists. No confidence interval is reported for the primary outcome.

What can a hypothesis test establish?

A hypothesis test evaluates data against a specified statistical model and null hypothesis. A p-value, when reported, describes how surprising the data would be under that null model; it is not the probability that a treatment works or that the null hypothesis is true. Interpretation requires the test, hypothesis, analysis population, and assumptions to be clear. The registry records zero analyses and does not report a p-value or a statistical testing plan. No inferential conclusion can therefore be drawn from a test result.

How should the planning illustration be read?

The registry describes a sample-size planning illustration based on a stated fraction of an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For time-to-event outcomes, the stated convention is a total number of events using the Schoenfeld method; other outcomes use participants per arm. These are planning assumptions, not evidence that the registered study had two arms. The trial itself is listed as single-group.

A planning illustration asks how much information might be needed under assumed conditions to detect a target effect. It is not an observed result and does not indicate the probability that this study detected an effect. It must not be interpreted as observed power. Numerical planning values are not reported in the registry record. The registry also does not report the trial’s own sample-size justification, target effect, or design assumptions.

Why are the safety percentages especially uncertain?

Percentages depend on their denominators. When the recorded number of participants at risk is very small, a single participant’s status can account for a large share of the listed group. That makes percentages sensitive to each observation and limits how broadly they can be interpreted. The serious-event listings include 100.0% entries, while the adverse-event group records one participant at risk and one affected participant. The registry does not give enough context to establish the denominator for every term or to infer event rates for a wider population.

General statistical methods can quantify sampling uncertainty when the relevant counts, denominators, definitions, and analysis procedures are available. Those elements are incomplete for interpreting the posted outcomes. The registry record does not report an analysis plan, interval estimates, or adjusted analyses. No recalculation or estimate of treatment effect can be justified from the information recorded.

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("TCR α/β Reagent System")
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  TCR α/β Reagent System  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 lists 12 outcome measures, including the primary severe acute GVHD-free survival outcome and multiple secondary outcomes. When a study evaluates several outcomes or performs repeated statistical tests, the chance of at least one apparently notable result can increase. General approaches to this issue include defining a primary outcome in advance, specifying a testing hierarchy, or adjusting inference for multiple comparisons. The registry record does not report a multiplicity strategy, so it is not possible to determine whether or how multiple testing was addressed.

The record lists zero analyses and does not post primary or secondary outcome results. It does not report how missing outcomes, loss to follow-up, or incomplete endpoint assessments were handled. The endpoint is assessed at 100 days post-SCT, but the record does not state how participants without an assessment at that time were classified or whether follow-up was complete.

Analysis populations are also not reported in the registry record. There is no description of which participants were included in outcome analyses, how protocol deviations were treated, or whether an intention-to-treat or other approach was used. With enrollment of 2 and no posted analysis, readers cannot evaluate the effect of exclusions, missing data, or outcome selection on the reported findings. These omissions limit both reproducibility and interpretation; they do not establish that any particular method was or was not used.

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: hepatic hemorrhage (100.0%), colonic perforation (100.0%), platelet count decreased (100.0%), respiratory failure (100.0%), acute kidney injury (100.0%).

The adverse-event information lists one participant at risk and one affected participant for serious events, and one at risk and one affected participant for other events. It records one death. Serious-event terms listed with 100.0% are Hepatic Hemorrhage, Colonic Perforation, Platelet Count Decreased, Respiratory Failure, Acute Kidney Injury, and Stroke.

These entries should be read as registry listings, not as comparative event rates or evidence of causation. A percentage is meaningful only alongside a clear denominator, event definition, and reporting period. The group-level record gives very small counts, and the registry does not explain the denominator or clinical context for each listed term. The 100.0% entries therefore should not be generalized to other transplant populations or interpreted as the probability of an event for a future participant.

The record does not state whether the listed events were judged related to the intervention, how severe they were beyond the serious-event classification, when they occurred, or how they were managed. Nor does it provide a comparative safety group. The listed death is a registry entry; its cause and relationship to the intervention are not reported in the registry record. These data cannot support a causal safety conclusion.

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

The registry record establishes that a Phase 2, single-group study evaluated ex vivo TCR αβ T-cell depletion in the context of mismatched-donor peripheral blood stem cell transplantation for hematologic malignancies. It specifies a primary outcome of severe acute GVHD-free survival at 100 days post-SCT and lists additional transplant-related outcomes. It also records enrollment of 2 and a terminated status.

The record does not report the primary endpoint result, secondary outcome results, or statistical analyses. It therefore does not show how many participants experienced the primary outcome, how uncertain an estimate might be, or how outcomes compared with another strategy. The lack of posted results cannot be interpreted as evidence for or against benefit or harm.

Even a reported outcome from this single group would have limits for causal interpretation. Without a concurrent control, differences from outcomes in another setting could reflect factors besides the intervention. A descriptive result would apply to the participants observed and would not establish what would happen under an alternative approach. The registry does not provide a basis for separating the intervention’s contribution from other influences on transplant outcomes.

The safety entries likewise require restraint. They identify recorded serious-event terms and a death, but do not report enough context to establish attribution, timing, or comparative risk. Enrollment of 2 also means the record describes a very small group, so broad claims about event frequency would not be justified.

In short, the registry permits a description of the study’s registered design and the outcomes it intended to assess. It does not provide the outcome evidence needed to estimate efficacy, precision, or comparative safety. No clinical recommendation follows from the information in the record.

14. Why This Trial Matters Statistically

This study raises statistical issues that are common in early-phase transplant research. The intervention is a cell-processing procedure, while the primary outcome is a participant-level clinical outcome measured after transplantation. Connecting a processing procedure with a clinical outcome requires transparent outcome definitions, complete follow-up, and an analysis that respects the study design.

The single-group design is important to interpretation. It can describe outcomes among enrolled participants if results are reported, but it does not create a direct comparison with an alternative prophylaxis strategy. Readers need to distinguish a clinical outcome count from an estimate of a treatment effect. The registry record does not post either a primary outcome estimate or a comparative analysis.

Small enrollment also highlights the role of precision. Counts from a very small group can be strongly influenced by each participant’s outcome, while uncertainty around a population-level estimate may be substantial. Reporting a point estimate alone would not resolve that concern; denominators and uncertainty intervals would be needed to show the limits of what the data can support. Those results are not reported in the registry record.

The registry lists multiple secondary outcomes, spanning GVHD, relapse, survival, recovery, and mortality. A clear statistical plan would help readers understand which outcomes were primary, how multiple testing was handled, and how missing data were treated. Those plan details are not reported. The record’s zero analyses makes it especially important not to infer results from the outcome list or adverse-event terms.

Finally, the terminated status and listed safety entries call for careful description rather than speculation. The record does not state why the study terminated or whether the listed events influenced that status. Separating recorded details from unanswered questions is essential when the available evidence is limited.

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 principal limitation for interpreting this trial record is the absence of posted outcome analyses. The primary endpoint is defined, but its count and the number assessed are not reported. No secondary outcome results, uncertainty estimates, or statistical test results are reported either. The registry record therefore does not support an estimate of the study’s clinical outcomes.

Enrollment is 2, and the study is listed as terminated. The reason for termination is not reported in the registry record. The record does not state whether all enrolled participants completed the 100-day assessment, whether follow-up was incomplete, or how missing assessments were handled. Without that information, even a descriptive outcome count would be difficult to interpret.

The design is single-group, with allocation recorded as NA and no masking. There is no concurrent control comparison described. Thus, the record cannot establish a comparative treatment effect. The protocol, eligibility criteria, participant characteristics, transplant details beyond the intervention description, and analysis populations are not reported in the registry record.

There are also reporting gaps around statistical methods. The registry lists 12 outcome measures and zero analyses, but does not report an analysis plan, multiplicity strategy, missing-data method, or sample-size justification for the trial. The planning illustration’s assumptions do not substitute for a documented trial design rationale or observed outcome analysis.

The adverse-event entries have limited context. The record lists a small number at risk and affected, serious-event terms with 100.0%, and one death, but does not report event timing, attribution, definitions, or a comparative group. These entries should not be used to infer causality or general event probabilities. Taken together, the design and reporting limitations leave substantial questions unanswered.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Ex Vivo TCR αβ T Cell Depletion for Graft-Versus-Host Disease Prophylaxis in Mismatched Donor Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies — NCT03717480.
• Registry record last updated 2022-05-10; status last verified 2022-04.
• Results first posted 2022-05-10.
• 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

NCT03717480 is a Phase 2, single-group study sponsored by Dana-Farber Cancer Institute. It concerns ex vivo TCR αβ T-cell depletion for GVHD prophylaxis in mismatched-donor peripheral blood stem cell transplantation for hematologic malignancies. The intervention uses the CliniMACS® TCR α/β Reagent System, with negative selection described using an automated CliniMACS® Plus device.

Enrollment is 2. The registry lists the study as terminated, with a start date of 2020-01-21 and primary completion on 2021-04-26. The primary outcome is the number of participants with severe acute GVHD-free survival at 100 days post-SCT. The record lists 12 outcome measures and zero analyses.

Primary and secondary results, analysis methods, and the reason for termination are not reported in the registry record. The adverse-event record lists one participant at risk and one affected participant for serious and other events, several serious-event terms at 100.0%, and one death. These entries do not establish causation or comparative risk.