Selective Depletion of CD45RA+T Cells From Allogeneic Peripheral Blood Stem Cell Grafts for the Prevention of GVHD: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Selective Depletion of CD45RA+T Cells From Allogeneic Peripheral Blood Stem Cell Grafts for the Prevention of GVHD (NCT00914940), a na phase 2 study. The primary outcome is Number of Participants With Acute Graft-vs-host Disease (GVHD): Grade I-IV, Including Those With no Reportable Acute GVHD.

2. Clinical Question

3. Trial Design

This registry record describes a phase II, single-group study sponsored by Fred Hutchinson Cancer Center. Enrollment is listed as 41. The study began on 2009-12-17, and primary completion is listed as 2019-12-01. Its status is terminated. The reason for termination and the timing or circumstances of that decision are not reported in the registry record.

Masking is recorded as none, and allocation is not applicable. These entries fit the listed single-group model: participants were not assigned between randomized treatment arms, and no concurrent control group is listed. This design can describe outcomes among enrolled participants, but it does not support a randomized estimate of the difference between the graft approach and an alternative.

The listed treatment approach involves selective depletion of CD45RA+ T cells from allogeneic peripheral blood stem cell grafts. The intervention list includes magnetic affinity cell sorting, peripheral blood stem cell transplantation, allogeneic hematopoietic stem cell transplantation, and T cell-depleted transplantation. It also lists fludarabine phosphate, tacrolimus, thiotepa, and total-body irradiation. The partial regimen description states that patients undergo total-body irradiation twice daily on days -10 to -7, receive thiotepa on days -6 and -5, and receive fludarabine on days -6 to -2. The full treatment and transplant protocol is not reported in the registry record.

The study lists transplant-related mortality by day 100, relapse within 5 years, and chronic GVHD among its secondary outcomes. Although the record lists five outcome measures, it reports no statistical analyses. Details of the planned statistical methods, analysis populations, and reasons for termination 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.

D0 to D100 Post-transplant

Reasons for not completing this period:

D101 to 2 Years Post-transplant

Reasons for not completing this period:

2 Years to 5 Years Post-transplant

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 Acute Graft-vs-host Disease (GVHD): Grade I-IV, Including Those With no Reportable Acute GVHD, measured over Within 360 days of transplant.

The primary endpoint is the number of participants with acute GVHD, including its severity grades and participants with no reportable acute GVHD, within 360 days of transplant. The outcome description says that acute GVHD severity is assessed across the skin, liver, and gastrointestinal tract, and that suspected cases are confirmed histologically by biopsy of an affected organ. Grading is described using the National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.0: Grade I is mild, Grade II moderate, Grade III severe, and Grade IV life-threatening.

This endpoint is relevant to the study’s stated purpose because GVHD is the complication the graft-manipulation strategy was intended to address. Recording severity as well as whether GVHD occurred can distinguish a count of affected participants from a description of how serious their disease was. Including participants with no reportable acute GVHD makes the outcome description encompass both the presence and absence of the event.

The endpoint definition does not establish what the observed result was. The participant counts by grade, the number with no reportable acute GVHD, and any uncertainty estimates are not reported in the registry record. The record therefore describes what was to be measured, but does not provide the primary outcome findings needed to assess the observed frequency or severity.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What can a single-group study estimate?

General statistical explanation: a single-group study records outcomes among participants who received the study approach. Counts and proportions can describe how often events were observed in that cohort, subject to the way outcomes were defined and follow-up was completed. Without a concurrent comparison group, the study does not directly estimate the contrast between the study approach and an alternative. Even a precisely measured event frequency would not, by itself, show what would have happened to the same participants under another treatment.

That design distinction applies to the registry record, which lists a single-group model and no allocation. There is no randomized control arm to balance known and unknown differences between groups. The record’s observed safety figures can be read descriptively, but they cannot be treated as excess risk attributable to the intervention. The registry record does not report adjusted comparisons or other analyses that might address differences in a nonrandomized comparison.

What does a confidence interval express?

General statistical explanation: a confidence interval communicates the statistical uncertainty around an estimate. A narrow interval indicates greater precision under the assumptions of the method, while a wide interval indicates less precision. An interval does not account automatically for biases in study design, missing outcome data, or limitations in measurement. It also does not turn an association into a causal effect.

No confidence interval for the primary endpoint is reported in the registry record. Because the outcome counts and analysis are also absent, the precision of the primary result cannot be assessed. The enrollment of 41 participants describes the planned or recorded cohort size, but enrollment alone does not reveal the amount of information available for a particular endpoint; follow-up completeness and the number of observed events also matter.

How should the endpoint be understood?

General statistical explanation: a binary event outcome records whether a participant experienced an event, while a severity classification adds distinctions among levels of the event. Here, the endpoint description specifies both acute GVHD and grades of severity, with participants who have no reportable acute GVHD included. Those features define the intended measurement. They do not tell the reader how many participants fell into each category.

When an outcome is reported as a count, the denominator and observation period are important. The primary outcome specifies a period within 360 days of transplant. The record does not report the number of participants assessed through that period, the grading results, or a statistical comparison. It is therefore not possible to infer a rate, a grade-specific distribution, or a confidence interval from the outcome definition alone.

How do the planning illustrations work?

The planning assumptions described for the sample-size illustrations use a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. They describe the effect to detect as a stated fraction of an observed effect. For time-to-event outcomes, the illustration is based on a total number of events; for other outcomes, it gives participants per arm for 80% power or other listed power levels.

General statistical explanation: such calculations ask how much information a future comparison might need under specified assumptions. A significance level sets a threshold for assessing compatibility with a null hypothesis, while power is the probability of detecting an effect of the assumed size under the model when that effect is present. These are planning concepts, not measurements of how likely the completed study was to show a result. Sample-size illustrations are not observed power and do not constitute evidence that an effect exists.

The study itself is single-group, whereas the illustration assumptions describe an equal-allocation comparison between two arms. That hypothetical setup should not be confused with the trial design. The registry record does not report a sample-size justification for the original study, nor does it report the observed primary endpoint effect used as an anchor for the illustrations. Numeric illustration outputs are not reported in the registry record.

Why can event counts be uncertain?

General statistical explanation: event counts can be imprecise when the number of observed events is limited, and estimates can be affected by differences in follow-up time or incomplete ascertainment. For time-to-event outcomes, the number and timing of events, censoring, and follow-up all contribute to the information available. The registry lists a relapse outcome within 5 years and transplant-related mortality by day 100, but it does not report their findings or the analysis methods used.

General statistical explanation: over-dispersion occurs when event variability is greater than a model assumes. If present, a model that assumes less variability may make uncertainty appear too small. Whether over-dispersion is relevant depends on the outcome and model; no count-model analyses or dispersion assessment are reported in the registry record. It would not be appropriate to presume that such a model was used for the binary primary endpoint.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists five outcome measures and identifies acute GVHD as the primary outcome. It also names secondary outcomes concerning transplant-related mortality by day 100, relapse within 5 years, and chronic GVHD. The record reports no statistical analyses. A complete statistical plan, including how outcomes were prioritized in analysis and how multiple comparisons were handled, is not reported in the registry record.

General statistical explanation: when researchers assess multiple outcomes or make multiple statistical comparisons, the chance of at least one apparently notable result can increase if no adjustment or interpretation strategy is specified. Multiplicity approaches can control error rates or help distinguish confirmatory outcomes from exploratory findings. The appropriate approach depends on the study’s design and aims. No adjustment method or multiplicity strategy is reported for this study.

The record does not report the primary endpoint counts, the secondary outcome results, or which participants contributed data to each outcome. It also does not report missing-data amounts, reasons for missingness, imputation methods, or sensitivity analyses. General statistical explanation: incomplete outcome data can bias an estimate if the likelihood of being observed is related to a participant’s outcome or characteristics. Knowing the number enrolled is not enough to establish complete follow-up for each outcome.

Analysis populations are not described in the registry record. It is therefore unclear whether the reported safety counts use all enrolled participants, a treated population, or another defined group, beyond the stated at-risk numbers in the safety listing. The listed at-risk denominators are 41 for both serious and other adverse events; the record does not provide a fuller definition of the analysis populations or explain how participants with incomplete follow-up were handled.

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: mucositis, oral (87.8%), cmv reactivation (48.8%), catheter related infection (22.0%), coagulase-negative staph bacteremia (19.5%), hypotension (17.1%).

The safety listing gives an overall study group of 41 participants at risk for serious adverse events, with 39 participants affected. For other adverse events, 41 participants were at risk and 41 were affected. The listing also reports 13 deaths. These are counts in the registry record; the timing, causes, and relationship of deaths to treatment are not reported in the registry record.

The listed serious adverse-event terms and percentages include oral mucositis, 87.8%; CMV reactivation, 48.8%; catheter related infection, 22.0%; coagulase-negative staph bacteremia, 19.5%; hypotension, 17.1%; and acute kidney injury, 9.8%. They describe events recorded in the study group, not a comparison with an untreated or alternative-treatment group. The record does not state the denominator or detailed counting rule for each term, so the percentages should be read as registry-reported figures rather than recalculated or reinterpreted.

General statistical explanation: one participant may experience more than one kind of adverse event, and event categories may therefore overlap. A count of participants affected by any serious event is not the same as a count of all event episodes. The listing does not give event-level timing, duration, recurrence, or attribution details. These figures provide a descriptive safety overview but do not establish causation or comparative risk.

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

The registry record establishes that a phase II, single-group study enrolled 41 participants and focused on selective depletion of CD45RA+ T cells from allogeneic peripheral blood stem cell grafts. Its primary outcome was defined around acute GVHD and severity within 360 days of transplant. The record also gives overall adverse-event counts and selected serious adverse-event terms. These registry entries describe the study’s design, aims, and some safety reporting.

They do not establish the observed primary endpoint result. The number of participants with acute GVHD, the grade distribution, and the number with no reportable acute GVHD are not reported in the registry record. The record also lacks statistical analyses and uncertainty estimates for that endpoint. It is therefore not possible to state from these data how often acute GVHD occurred or how precisely its frequency was estimated.

The single-group design also limits what any descriptive outcome could mean. General statistical explanation: outcomes observed after an intervention may reflect several influences, including participant characteristics, other treatments, and clinical care. A randomized comparison is designed to reduce some sources of systematic difference between groups. Since no randomized comparator is listed, this study does not directly estimate a treatment effect relative to another strategy.

The serious and other adverse-event counts show that events were recorded among participants, and the record lists 13 deaths. They do not establish that the study approach caused those events or deaths. The record does not report causes of death or event attribution. Likewise, listed secondary outcomes do not become findings simply because they were planned: their results are not reported in the registry record.

The most defensible interpretation is narrow. The registry describes an intended transplant approach and outcomes of interest, but does not provide the primary outcome results needed to assess the stated GVHD question. The safety listing is descriptive and has no comparative group. No conclusion about benefit, lack of benefit, or comparative safety follows from the information reported.

13. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the distinction between a clearly specified clinical question and a reported statistical result. The registry defines an acute GVHD endpoint, a time frame within 360 days, and a grading framework. Those details help identify what the investigators intended to measure. Yet the participant results and statistical analyses for that endpoint are not reported in the registry record. A precise endpoint definition cannot substitute for the data needed to estimate its frequency or uncertainty.

The design also shapes the claims that can be supported. A single-group phase II study can provide descriptive experience with a transplant approach, but it cannot supply a randomized estimate against an alternative. That limitation remains even if outcome counts are available. In this record, the lack of primary results further restricts interpretation: the proposed clinical question cannot be resolved from the posted results.

The safety listing reinforces why counts need context. Serious adverse events affected 39 of 41 participants, other adverse events affected 41 of 41, and 13 deaths are listed. These figures are important descriptors of the cohort, but without a comparator, event attribution, and fuller timing and follow-up details, they do not quantify excess risk caused by the intervention.

Finally, the record shows why planning calculations and completed-study evidence must be kept separate. The sample-size assumptions describe a hypothetical two-arm comparison, not the single-group design, and planning illustrations are not observed power. Statistical interpretation depends on matching the design, endpoint, analysis, and reported uncertainty to the claim being considered.

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 for interpreting efficacy is that the registry record does not report the primary endpoint results. It does not give the numbers of participants with acute GVHD by grade, the number without reportable acute GVHD, or an estimate of uncertainty. Although the endpoint is specified within 360 days of transplant, the record does not report completeness of follow-up or endpoint ascertainment.

The single-group design has no randomized control comparison. It therefore cannot directly distinguish outcomes associated with the study approach from outcomes that might have occurred under another transplant strategy. Masking is listed as none, and the record does not describe independent outcome adjudication beyond stating that suspected acute GVHD cases would be confirmed histologically.

The registry record does not report detailed participant characteristics, eligibility criteria, the full treatment protocol, or the reason the study was terminated. Its arm description is incomplete, limiting the detail available about how the transplant regimen was delivered. The record also does not report a statistical analysis plan, a sample-size justification for the trial, analysis populations, missing-data handling, or multiplicity procedures.

Safety interpretation is limited by the absence of a comparator and by missing details on event timing, causes of death, and attribution. The percentages for serious adverse-event terms are listed, but the denominator and detailed counting rules for each term are not reported in the registry record. The results of the listed secondary outcomes are also not reported, limiting interpretation of relapse, chronic GVHD, and transplant-related mortality.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Selective Depletion of CD45RA+T Cells From Allogeneic Peripheral Blood Stem Cell Grafts for the Prevention of GVHD — NCT00914940.
• Registry record last updated 2020-08-20; status last verified 2020-07.
• Results first posted 2020-08-20.
• 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.

18. Record Summary

The registry describes NCT00914940, a phase II, single-group study of selective CD45RA+ T-cell depletion from allogeneic peripheral blood stem cell grafts for prevention of GVHD. Fred Hutchinson Cancer Center is listed as sponsor. Enrollment is 41; the start date is 2009-12-17, primary completion is 2019-12-01, and the status is terminated.

The primary outcome concerns acute GVHD and severity within 360 days of transplant. Listed secondary outcomes include transplant-related mortality by day 100, relapse within 5 years, and chronic GVHD. The safety listing reports 39 of 41 participants affected by serious adverse events, 41 of 41 affected by other adverse events, and 13 deaths. The registry record does not report primary or secondary outcome results, statistical analyses, a reason for termination, or a randomized comparison group.