Study of Plerixafor for Rescue of Poor Mobilizers in Autologous Stem Cell Transplant: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Plerixafor for Rescue of Poor Mobilizers in Autologous Stem Cell Transplant (NCT00901225), a na phase 2 study. The primary outcome is Number of Participants Who Achieved > or Equal to 2 X 10(6)CD34+ Cells/kg Within 3 Days of Apheresis After Receiving Plerixafor With G-CSF..

2. Clinical Question

In statistical terms, the study asks whether the rescue regimen is followed by attainment of a prespecified cell-collection threshold in this selected group. The primary outcome is a count of participants meeting that threshold, rather than a comparison of average cell counts between treatment groups. Without a reported outcome count, the registry record cannot establish the observed proportion meeting the target or how precisely it was estimated.

3. Trial Design

This is a phase 2, single-group study with 21 enrolled participants. The registry record lists the study as completed, with a start date of 2009-05 and primary completion in 2010-08. Duke University is the listed sponsor. Masking is listed as none, so the study was open label. Allocation is listed as NA; no randomized allocation or separate control arm is described.

Participants were selected for an inadequate response to G-CSF mobilization. The arm description defines this as a CD34+ cell count <20 cells/ul after 5 days of G-CSF. They received G-CSF plus plerixafor. The brief summary describes the study hypothesis as achieving > or equal to 2 X 10(6) CD34+ cells/kg within 3 days of apheresis after adding plerixafor to G-CSF.

A single-group design can describe outcomes following the intervention in the enrolled participants. It cannot, by itself, separate the effect of the intervention from other explanations for the observed outcomes, because no concurrent comparison group is described. This design feature is central to how the results should be interpreted; it is not a randomized estimate of the difference between two treatments.

The registry record lists six outcome measures, including the primary endpoint and secondary outcomes concerning grade III/IV toxicity, graft failure, time to an absolute neutrophil count >500, durability of engraftment, and platelet engraftment. It does not report a statistical analysis plan, analysis populations, or outcome results for these measures. Further details of eligibility, follow-up, and conduct 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.

Before assignment: All patients deemed to be poor mobilizers to G-CSF as a single agent, were eligible for enrollment (assuming protocol eligibility criteria were met).

Overall Study

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 Who Achieved > or Equal to 2 X 10(6)CD34+ Cells/kg Within 3 Days of Apheresis After Receiving Plerixafor With G-CSF., measured over 5 days after receiving G-CSF.

The primary endpoint is the number of participants who achieved > or equal to 2 X 10(6) CD34+ cells/kg within 3 days of apheresis after receiving plerixafor with G-CSF. It is a binary participant-level outcome: each participant either meets the stated threshold within the stated period or does not. The endpoint is intended to capture whether collection reached the target the study set out to assess.

For a binary endpoint, the count meeting the criterion and the total number assessed are needed to describe the observed rate. A confidence interval can then express the statistical uncertainty around that rate; it does not guarantee that the true rate lies within any particular interval. The registry record does not report the number achieving the threshold, the number included in the endpoint analysis, or an interval estimate. Accordingly, the observed rate and its precision are not reported in the registry record.

There is a timing detail to keep in mind. The primary outcome title specifies achievement within 3 days of apheresis, while the registry timeframe field says “5 days after receiving G-CSF.” The relationship between these time descriptions is not clarified in the registry record. The endpoint’s clinical interpretation depends on a clear definition of when assessment occurs, so this wording should not be silently treated as interchangeable.

The endpoint is a collection outcome, not a direct comparison of treatment strategies. It does not by itself describe all later transplant outcomes, safety, or durability. Those topics appear among the listed secondary outcomes, but their results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group result estimate?

In general, a single-group study can estimate the frequency of an outcome among participants who receive the studied regimen, assuming the outcome and analysis population are clearly defined and observed. It does not directly estimate the difference between that frequency and what would have happened under a comparator. That distinction matters because a result observed after treatment may also reflect participant characteristics, the course of illness, measurement practices, or other care.

This study is described as single group, with allocation listed as NA and masking listed as none. No randomized comparator is described. The primary question is therefore framed around attaining a collection threshold after plerixafor with G-CSF in participants selected for low CD34+ counts after G-CSF. It is not a randomized comparison of rescue treatment against another strategy.

How should a binary endpoint be read?

In general, a binary endpoint classifies each participant according to whether a defined event occurred. For the stated primary endpoint, the event is reaching > or equal to 2 X 10(6) CD34+ cells/kg within 3 days of apheresis after receiving the combination. The count of participants meeting the criterion is meaningful only alongside the number assessed. The proportion is a concise description of frequency, but the registry record does not report the event count or endpoint denominator.

A confidence interval is a way to represent uncertainty in an estimated quantity. For a binary endpoint, an interval around the observed proportion can show that a finite study does not determine the underlying frequency with perfect precision. Interval width generally depends on the amount of information and the observed frequency. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be evaluated from this record.

What does the design permit?

Random allocation, when used, aims to make treatment groups comparable in expectation and supports a direct estimate of a treatment contrast. This study has no reported randomized comparison. As a result, any observed outcome frequency would describe the enrolled group under the regimen, but would not alone show how outcomes would differ under an alternative. The registry record does not report a control-group outcome or an adjusted comparative estimate.

Open-label status means masking is listed as none. In general, lack of masking can matter when outcome assessment or care decisions involve judgment. The primary endpoint is expressed as a numerical collection threshold, but the registry record does not describe assessment procedures, independent review, or safeguards for ascertainment. It is not possible to determine their role from the record.

What is and is not available about analysis?

The registry record lists no analysis records. It does not report a statistical analysis plan, a method for estimating the primary outcome, an interval method, covariate adjustment, or a prespecified subgroup analysis. It is therefore not possible to characterize the sponsor’s analytical approach for the primary endpoint based on the registry record. No primary outcome result is reported, either.

The sample-size planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Such assumptions describe a planning exercise, not the design of this single-group trial. The illustration is not observed power and should not be interpreted as evidence that a particular treatment effect was demonstrated. The registry record does not report a trial-specific sample-size justification.

In general, statistical power is a design property tied to a specified effect, variability, sample size, and analysis. It is not a measure of the probability that a study result is true, and calculating power after observing data does not resolve uncertainty about the estimate. Sample-size planning values are hypothetical illustrations, not participants observed in the trial. The record does not state that the planning assumptions were used to design this study.

Why does outcome definition matter?

Interpretation depends on the threshold, assessment window, and population to which an endpoint applies. Here, the primary endpoint title specifies a target within 3 days of apheresis, while the timeframe field states 5 days after receiving G-CSF. The registry record does not clarify the relationship between these descriptions. It also does not report whether the endpoint was assessed for every enrolled participant or how outcomes outside the stated window were classified.

In general, a clearly prespecified endpoint reduces ambiguity about what counts as an event and when it is measured. Missing outcome data can also affect interpretation: if some participants are not assessed, the analyzed group may differ from the enrolled group. The registry record does not describe missing-data handling or endpoint completeness. These methodological details remain unknown rather than being assumptions that can be filled in from the stated study question.

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("G-CSF Plus Plerixafor")
n      <- c(20)
events <- c(15)
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  G-CSF Plus Plerixafor  20  15  75.0  50.9  91.3  53.1  88.8  52.8  88.7

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists six outcome measures: the primary collection endpoint and secondary outcomes for grade III/IV toxicity, graft failure, days to an absolute neutrophil count >500, durability of engraftment, and platelet engraftment. It does not report a multiplicity strategy, such as whether one endpoint was designated as the sole basis for confirmatory inference or how multiple statistical tests would be interpreted. No analysis records are listed. Consequently, no multiplicity-adjusted or unadjusted outcome conclusions are reported in the registry record.

In general, assessing several outcomes can increase the chance of finding at least one apparently notable result by chance if each is tested separately. A prespecified strategy can clarify which outcomes are confirmatory and how uncertainty should be interpreted across them. The registry record does not provide enough information to determine whether such a strategy was used. The existence of several listed outcomes does not establish that each was analyzed or that results were available.

The registry record does not report missing-data methods, the number assessed for each outcome, or analysis populations. It is therefore unknown whether all enrolled participants were included in each outcome analysis, how any unavailable measurements were handled, or whether different populations were used for efficacy and safety. Enrollment of 21 should not be treated as the denominator for every endpoint without a reported analysis denominator.

These omissions limit reproducibility and interpretation. They do not establish that data were missing, that outcomes were selectively reported, or that an analysis was not performed; those matters are not reported in the registry record.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event record lists 21 participants at risk for serious adverse events and 0 participants affected. For other adverse events, it lists 21 participants at risk and 4 affected. These are participant counts in the single G-CSF plus plerixafor group. The record does not give event descriptions for the other adverse events, and no serious adverse-event terms are listed.

These counts do not indicate how long participants were observed for safety, whether events were considered related to treatment, or whether a participant could have experienced more than one event. Those details are not reported in the registry record. Deaths are listed as null, which does not establish a count of zero; deaths are not reported in the registry record.

In general, adverse-event counts describe events recorded under a specified observation and reporting process. Without a comparator group, they do not estimate a relative difference in risk. The registry record’s figures should therefore be read as limited descriptive safety information, not as a comparative safety analysis.

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

The study defines a specific clinical research question: among patients with an inadequate CD34+ response after G-CSF mobilization, how many reach a stated cell-collection threshold after receiving plerixafor with G-CSF? The registry record reports that 21 participants were enrolled and describes the primary endpoint. It does not report the number who achieved the target. The primary result, including its rate and precision, is therefore not reported in the registry record.

Even a reported single-group rate would describe outcomes in this selected study population, not a randomized difference from another treatment. A comparator is needed for a direct estimate of the difference between strategies. Because the study is single group and allocation is listed as NA, the record does not support a causal treatment comparison.

The endpoint itself is limited to reaching a collection threshold within a specified period. It does not encompass every aspect of transplant success, longer-term outcome, or safety. The registry lists secondary outcomes related to toxicity and engraftment, but their results are not reported in the registry record. The timing wording also needs care: the endpoint title states within 3 days of apheresis, whereas the timeframe field states 5 days after receiving G-CSF.

The safety counts offer limited descriptive information: 0 serious adverse events among 21 participants at risk and 4 participants with other adverse events among 21 at risk. Event details, attribution, observation time, and deaths are not reported in the registry record. These figures cannot establish how safety compares with another regimen.

Thus, the registry record establishes the study’s intended question and design, but does not report the primary outcome needed to judge how often the collection target was achieved. It also does not provide analysis details or a comparative group. No conclusion about treatment benefit or lack of benefit follows from the absence of a posted outcome result.

14. Why This Trial Matters Statistically

Statistically, this study illustrates the distinction between a clearly stated clinical target and a reported estimate of how often that target was reached. The target is specific: > or equal to 2 X 10(6) CD34+ cells/kg within 3 days of apheresis after plerixafor with G-CSF. Yet the registry record does not report the number of participants meeting it. A question can be precisely framed while its result remains unavailable in the record.

The single-group design is also important. It can be used to describe an outcome following a rescue regimen, but it does not supply a randomized comparison. Readers should distinguish a frequency within the treated group from a treatment effect, which is a contrast between outcomes under different treatment strategies. That distinction is essential when interpreting any single-arm study.

The study further shows why endpoint timing and denominators matter. The title and timeframe field use different time descriptions, and the number assessed for the primary endpoint is not reported. Without consistent timing and a stated denominator, even a reported event count would be difficult to interpret fully.

Finally, the limited safety counts demonstrate the scope of registry information: counts can be reported without event descriptions, observation periods, or a comparator. Those details affect what can be concluded. The record supports a careful description of design and reporting gaps, rather than a quantitative conclusion about the primary endpoint.

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 primary limitation for interpretation is that the registry record does not report the primary endpoint result. It gives no number of participants achieving the collection threshold, no endpoint denominator, and no estimate of uncertainty. Enrollment was 21, but that does not establish how many had an evaluable endpoint.

The single-group design provides no concurrent comparison, and allocation is listed as NA. The study therefore cannot estimate a randomized contrast between plerixafor plus G-CSF and another strategy. Masking is listed as none, while assessment procedures and outcome-adjudication details are not reported in the registry record.

The primary endpoint timing is not fully clear from the record: its title specifies within 3 days of apheresis, while the timeframe field says 5 days after receiving G-CSF. The registry record does not reconcile these descriptions. Eligibility detail beyond the stated low CD34+ count and the listed conditions is not reported in the registry record.

Analysis populations, missing-data handling, statistical methods, multiplicity procedures, and a trial-specific sample-size justification are not reported in the registry record. These gaps prevent a full assessment of how outcomes were analyzed. For safety, counts are reported but event terms, attribution, duration of observation, and deaths are not. The registry record’s completed status does not resolve these limitations or substitute for the missing outcome results.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of Plerixafor for Rescue of Poor Mobilizers in Autologous Stem Cell Transplant — NCT00901225.
• Registry record last updated 2014-05-07; status last verified 2014-04.
• Results first posted 2014-05-07.
• 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, open-label, single-group study sponsored by Duke University. It enrolled 21 participants and examined G-CSF plus plerixafor as rescue mobilization for patients with a CD34+ count <20 cells/ul after 5 days of G-CSF. The listed conditions are multiple myeloma, Non-Hodgkins Lymphoma, and Hodgkins Disease.

The primary endpoint is the number reaching > or equal to 2 X 10(6) CD34+ cells/kg within 3 days of apheresis. The record does not report this outcome result. It reports 0 serious adverse events among 21 at risk and 4 participants with other adverse events among 21 at risk. Analysis methods, endpoint denominator, and further safety details are not reported in the registry record.