Anti-thymocyte Globulin and Melphalan in Treating Patients With Relapsed Multiple Myeloma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Anti-thymocyte Globulin and Melphalan in Treating Patients With Relapsed Multiple Myeloma (NCT00635024), a na phase 2 study. The primary outcome is Hematological Response Rate Defined as the Number of Participants Who Achieve a Confirmed Response.

2. Clinical Question

This is a narrow question about response in a small, single-group trial, not a comparative question about whether the combination produces better outcomes than another approach. The registry lists overall survival, progression-free survival, duration of response, and severe non-hematological adverse events as secondary outcomes. Although these outcomes indicate areas the trial intended to assess, their results are not reported in the registry record. Without a reported primary response count or comparator, the record does not permit an estimate of a treatment contrast or a statistical assessment of comparative efficacy.

3. Trial Design

The registry describes NCT00635024 as a phase II trial of anti-thymocyte globulin and melphalan in patients with relapsed multiple myeloma. Mayo Clinic is listed as the sponsor. The model is single-group, allocation is recorded as not applicable, and masking is none. These design features mean that the registry does not describe random assignment, blinding, or a concurrent control group.

The listed enrollment is 1. The record states that 1 participant was evaluable for the primary endpoint. The trial status is terminated, with a start date of 2008-05 and primary completion recorded as 2008-07. The reason for termination is not reported in the registry record, so no conclusion about why it ended can be drawn from these entries.

The intervention group is named Anti-thymocyte Globulin/Melphalan. The description identifies both treatments as part of the regimen. The registry does not report additional details about treatment delivery, dose modifications, adherence, or participant-level treatment exposure beyond the regimen description.

The primary outcome was a count of participants achieving a confirmed hematological response within the stated timeframe. The record also lists overall survival, progression-free survival, duration of response, and the number of participants with severe non-hematological adverse events as secondary outcomes. It does not report outcome analyses. A protocol-level statistical analysis plan, sample-size justification, interim-analysis plan, or detailed analysis-population definition is not reported in the registry record. The design can therefore be described from its registry fields, but its planned inferential procedures cannot be reconstructed.

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:

Analysis population for the primary outcome, as defined in the registry: One participant was evaluable for the primary endpoint.

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 Hematological Response Rate Defined as the Number of Participants Who Achieve a Confirmed Response, measured over 4 months.

The primary endpoint is the number of participants who achieved a confirmed hematological response. The registry defines confirmation as a response observed on 2 consecutive evaluations during the first 4 months of treatment. The response categories include complete response, very good partial response, and partial response, each with specified laboratory or marrow criteria.

For complete response, the criteria include disappearance of M-protein from serum and urine, normalization of the free light chain ratio, and <5% plasma cells in bone marrow. Very good partial response includes a >=90% reduction in serum M-component and a urine M-component <100 mg per 24 hours. Partial response includes reductions in serum or urine M-component, or a decrease in the difference between involved and uninvolved free light chain levels, according to the definitions in the registry.

A response endpoint is used to describe whether participants meet a prespecified disease-response definition over a stated period. Requiring confirmation on consecutive evaluations distinguishes a confirmed response from a response observed only once. These definitions clarify what would count as an event, but the registry record does not report the number who met the endpoint. It therefore gives the outcome definition without a reported primary outcome result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods are difficult to evaluate because the registry record does not report analyses for the listed outcomes. It identifies a count-based primary endpoint and several secondary outcomes, but does not provide a statistical analysis plan, estimates, uncertainty intervals, or tests. General explanations of the relevant methods can clarify what would ordinarily be needed to interpret these outcomes; they do not fill in analyses that are absent from the record.

What does a count-based response endpoint represent?

The primary outcome is a count of participants meeting the confirmed-response definition. For a count to convey response frequency, readers would generally also need the relevant analysis denominator and a clear account of who was included. The registry says that 1 participant was evaluable for the primary endpoint, but it does not report the count meeting the response definition. It also does not state a response proportion or an uncertainty interval. The endpoint criteria define the event; they do not provide the event result.

In general, an uncertainty interval communicates the range of values compatible with an estimate under the model and assumptions used. For a response frequency, the interval would describe how imprecisely the observed data estimate the underlying response frequency. It cannot be recovered from an endpoint definition alone. No interval or statistical model for this outcome is reported in the registry record.

Why does the study design matter for inference?

In general, a single-group study observes outcomes in participants who receive the study regimen without a concurrent control group. It may describe outcomes within that group, but it does not directly estimate how outcomes would differ under another treatment or under a control condition. Random allocation, when used, can support a balanced comparison by assigning participants to groups; this record does not describe randomized allocation. The registry identifies no comparator and no masking. These design details constrain what could be concluded even if an outcome estimate were available.

Blinding is a general method for limiting the influence of knowledge about treatment assignment on outcome assessment or reporting. The record lists masking as none. The registry does not explain how the response assessments were performed or whether independent review was used. Such details should not be presumed. For an endpoint involving laboratory measures and confirmation across evaluations, transparent assessment procedures can be important to understanding how the outcome was established.

How should the secondary outcomes be understood?

The secondary outcomes include overall survival and progression-free survival, which are time-to-event outcomes in general statistical practice. Their analysis typically depends on event and follow-up information, as well as clear definitions of the event and censoring. The registry lists these outcomes but does not report their definitions beyond their names, event counts, follow-up summaries, or analyses. Duration of response also requires information about who responded and how response duration was defined; those results are not reported in the registry record.

The number of participants with severe non-hematological adverse events is a count outcome. Interpreting such a count requires knowing which events met the severity and category definitions, the period of observation, and the group considered at risk. The safety data include a group-level count for other adverse events and a serious-adverse-event count, but the record does not give serious-event terms. It does not report a detailed safety analysis plan.

What can the planning assumptions establish?

The registry's sample-size assumptions describe planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The stated illustration considers the effect to detect as a fraction of the observed effect; time-to-event illustrations are expressed as total events, while other illustrations are expressed as participants per arm. These are planning assumptions, not evidence that the trial had a particular probability of detecting an effect. Sample-size illustrations are not observed power.

The record does not report the primary response result needed to interpret an illustration based on the observed effect. It also does not identify these assumptions as the trial's own design plan. They cannot be treated as a justification for the enrollment, an account of the trial's intended analysis, or a substitute for the missing result. In general, sample-size planning depends on choices about the outcome, target effect, variability or event frequency, allocation, and statistical test. Those choices are not fully documented as a trial-specific plan in the registry record.

Over-dispersion is a general issue for count data when observed variability exceeds what a simple model assumes. It can make model-based uncertainty too narrow if the model fails to account for that extra variability. The registry record does not report a count model, a dispersion assessment, or enough outcome data to assess whether over-dispersion is relevant to this trial. No particular model should therefore be attributed to the investigators.

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("Anti-thymocyte Globulin/Melphalan")
n      <- c(1)
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  Anti-thymocyte Globulin/Melphalan  1  0  0.0  0.0  97.5  0.0  79.3  1.3  84.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary response outcome alongside secondary outcomes for overall survival, progression-free survival, duration of response, and severe non-hematological adverse events. When a study examines multiple outcomes, multiplicity can arise because repeated statistical testing may increase the chance of at least one apparently notable result. General approaches include designating a primary outcome in advance, adjusting tests, or interpreting secondary findings as exploratory. The registry record does not report whether any multiplicity adjustment or other strategy was planned or used.

No outcome analyses are reported in the registry record. Consequently, there are no posted estimates or tests across outcomes to compare, and no basis for determining whether the outcome hierarchy affected interpretation. The record identifies the primary endpoint, but does not supply a statistical analysis plan or explain how secondary outcomes were to be interpreted relative to it.

The record states that 1 participant was evaluable for the primary endpoint, but does not describe the analysis populations for the secondary outcomes. It does not give a general definition of evaluability, an intention-to-treat analysis population, or rules for excluding participants from analyses. A reader cannot assume that the same population was used for every outcome.

Missing-data handling is also not reported in the registry record. There is no description of how incomplete response assessments, missing follow-up, or unavailable outcome measurements were handled. The registry does not say whether missing outcomes were imputed, treated as non-events, excluded, or addressed in another way. These are different analytical choices and should not be inferred from the endpoint description or the fact that the trial was terminated.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The safety record lists an Anti-thymocyte Globulin/Melphalan group. For serious adverse events, 1 participant was at risk and 0 were affected. For other adverse events, 1 participant was at risk and 1 was affected. These are counts within the listed group; they are not comparisons between treatments and do not establish relative safety.

The registry provides no serious adverse-event terms in its listing of top serious terms. That means the specific serious events are not reported in the registry record. The death count is also not reported in the registry record. The record names severe non-hematological adverse events as a secondary outcome, but does not report an analysis of that outcome.

Safety counts describe what is recorded for the study group and should be read in light of the limited enrollment and the absence of a comparator. They do not establish the frequency of uncommon events or predict risk in a broader population. The record does not provide detailed information on adverse-event definitions, duration of observation, severity grading, or attribution to treatment. Those details should not be inferred from the counts.

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

The registry record establishes that a phase II, single-group study of anti-thymocyte globulin with melphalan was conducted in patients with relapsed multiple myeloma and is now listed as terminated. It defines a confirmed hematological response endpoint within the first 4 months of treatment and reports that 1 participant was evaluable for that endpoint. It does not report how many participants achieved a confirmed response.

That absence prevents a direct description of the primary outcome. It also prevents calculation or interpretation of a response estimate from the registry record. The listed secondary outcomes do not substitute for the missing primary result, because their analyses are also not reported. A rationale for combining treatments describes why the study may have been considered, but it is not evidence of a clinical outcome.

The study has no comparator group, so even a reported response would describe outcomes in the study group rather than a randomized difference from another treatment. In general, a comparative claim requires a suitable comparison and an analysis that accounts for the study design. Neither a treatment advantage nor a lack of benefit can be concluded from the information in this record.

The safety counts report 0 serious adverse events among 1 participant at risk and 1 other adverse event among 1 at risk. Those figures are limited descriptions of recorded events, not definitive safety estimates. The record does not identify the serious-event terms or report a death count. It also does not explain why the study was terminated. These gaps make it inappropriate to infer a reason for termination or a broader safety profile.

Overall, the posted information supports an account of the trial's question, design, endpoint definition, and limited safety counts. It does not support a conclusion about the efficacy of the regimen, the magnitude or precision of a response effect, or outcomes relative to another treatment. Missing results should be treated as unreported, rather than as evidence that an outcome did or did not occur.

14. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the distinction between defining an outcome and reporting its result. The registry gives a detailed confirmed-response definition, including confirmation on 2 consecutive evaluations during the first 4 months of treatment. Yet the primary response count itself is not reported in the registry record. Without that count, the endpoint cannot be translated into an observed response estimate.

The single-group design also demonstrates why a study question and a treatment comparison are not the same thing. The record describes an intervention and a target population, but no concurrent comparator. A single-group result, if reported, could describe the observed experience in that group; it could not directly estimate how outcomes differ from another approach. This distinction is important when reading claims that might otherwise overstate what a study design can establish.

The record also separates registered outcomes from completed analyses. It names survival, response duration, and adverse-event outcomes, but does not report their results. A list of intended outcome topics is not evidence that a specific analysis was completed or that an outcome occurred. Similarly, sample-size planning assumptions are not observed power and do not replace outcome data.

Finally, a terminated status is a record of trial status, not an explanation of what happened. Since the reason is not reported, statistical interpretation must avoid attributing the termination to particular results or operational circumstances. These distinctions help readers assess what can be learned from registry information while keeping unreported results and design details separate from evidence.

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 key trial-specific limitation is the absence of a reported primary response count. The registry states that 1 participant was evaluable, but does not report whether that participant met the confirmed-response definition. The record therefore does not provide a primary efficacy estimate or its precision.

Enrollment is listed as 1, and the study has a single-group design with no comparator. These features leave no basis for a randomized treatment contrast and limit the ability to generalize any group-level description. The record is also unmasked. It does not report how response assessments were conducted, whether assessments were independently reviewed, or what procedures were used to reduce assessment bias.

The trial is marked terminated, but the reason is not reported in the registry record. The record does not provide a full account of participant follow-up, treatment exposure, adherence, or outcome-specific analysis populations. It does not report how missing outcome data were handled, and it does not give a statistical analysis plan or multiplicity strategy.

Although several secondary outcomes are named, their definitions and analyses are not reported. Serious adverse-event terms are not listed, and the death count is not reported in the registry record. The limited safety counts cannot establish a comprehensive safety profile. Finally, the planning assumptions are described as illustrations, not as the trial's own design justification; the record does not provide enough outcome information to interpret their basis as a trial-specific estimate.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Anti-thymocyte Globulin and Melphalan in Treating Patients With Relapsed Multiple Myeloma — NCT00635024.
• Registry record last updated 2017-02-10; status last verified 2011-08.
• Results first posted 2010-10-18.
• 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

NCT00635024 is a phase II, single-group, unmasked trial sponsored by Mayo Clinic, studying anti-thymocyte globulin with melphalan in patients with relapsed multiple myeloma. The registry lists enrollment of 1, a start date of 2008-05, primary completion in 2008-07, and status as terminated.

The primary endpoint was the number of participants achieving a confirmed hematological response during the first 4 months of treatment, with confirmation on 2 consecutive evaluations. The record states that 1 participant was evaluable but does not report the primary response count or any outcome analyses. Secondary outcomes include overall survival, progression-free survival, duration of response, and severe non-hematological adverse events.

The safety entries report 0 serious adverse events among 1 participant at risk and 1 other adverse event among 1 at risk. Serious-event terms and the death count are not reported in the registry record. The reason for termination and the trial's detailed statistical analysis plan are also not reported.