Ixazomib Citrate, Pomalidomide, Dexamethasone, Stem Cell Transplant in Treating Relapsed or Refractory Multiple Myeloma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ixazomib Citrate, Pomalidomide, Dexamethasone, Stem Cell Transplant in Treating Relapsed or Refractory Multiple Myeloma (NCT03202628), a na phase 2 study. The primary outcome is Progression-free Survival at 18 Months (PFS18) Defined as the Proportion of Patients Alive and Free From Disease Progression at 18 Months From Study Entry.

2. Clinical Question

3. Trial Design

This is a phase II, single-group trial registered as NCT03202628 and sponsored by Mayo Clinic. The registry lists recurrent and refractory plasma cell myeloma as the conditions under study. Enrollment is 8, the study status is completed, the start date is 2017-07-24, and the primary completion date is 2021-04-13.

The intervention is a treatment sequence involving ixazomib citrate, pomalidomide, dexamethasone, and autologous hematopoietic stem cell transplantation. The registry's official title describes induction with the three drugs before salvage transplantation, consolidation with the three drugs, and ixazomib maintenance. The available arm description specifies induction courses 1-4: ixazomib on days 1, 8, and 15; pomalidomide on days 1-21; and dexamethasone on days 1, 8, 15, and 22. Treatment repeats every 28 days for courses 1-3 and every 56 days for course 4. Further treatment details are not reported in the registry record.

The design has no randomized allocation and no masking. Its evidence is therefore descriptive of the enrolled group, rather than a direct comparison against a concurrent control. The registry reports 7 outcome measures and 0 analyses, but numerical results for the primary endpoint are not reported in the registry record. Details about the protocol's sample-size justification, planned interim analyses, and statistical analysis plan beyond the endpoint description 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.

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 Progression-free Survival at 18 Months (PFS18) Defined as the Proportion of Patients Alive and Free From Disease Progression at 18 Months From Study Entry, measured over 18 months.

The primary endpoint is progression-free survival at 18 months, expressed as the proportion of participants alive and free from disease progression at 18 months from study entry. It combines two clinically relevant events for this outcome: death and disease progression. A participant must be alive and without documented progression at the specified time to count as a success under the registry's stated definition.

The registry describes a direct proportion estimate, calculated as successes divided by evaluable patients, and exact binomial 95% confidence intervals for the true success proportion. It also states that a Kaplan-Meier estimate with 95% confidence intervals will be reported if participants are censored before 18 months. These approaches address different data situations: the direct proportion uses evaluable participants at the endpoint, while Kaplan-Meier estimation can use follow-up time from participants whose endpoint status is censored earlier, subject to assumptions about censoring.

This endpoint gives a time-specific description of the study group, not a comparison of treatment strategies. The registry record does not report the observed PFS18 proportion, its confidence interval, the number evaluable, or the number of participants classified as successes. The endpoint's intended measurement is therefore described, but its numerical result cannot be assessed from the registry information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry's primary endpoint description sets out two possible ways to estimate PFS18. The first is a proportion: the number of participants who meet the success definition divided by the total number of evaluable patients. The second is a Kaplan-Meier estimate if participants are censored before 18 months. The stated uncertainty measure is a 95% confidence interval. These are planned methods described in the record; the numerical estimate and interval are not reported in the registry record.

What does a confidence interval communicate?

In general, a confidence interval expresses uncertainty around an estimate. A narrow interval indicates greater statistical precision under the method's assumptions; a wide interval indicates less precision. It is not a guarantee that the true value falls inside the particular interval, and it does not address every source of uncertainty, such as selection of participants or differences between the study group and a broader clinical population. Here, an exact binomial 95% confidence interval is specified for the proportion approach. The actual interval cannot be interpreted because it is not reported.

Exact binomial methods are designed for a proportion formed from a count of successes and a count of evaluable observations. They avoid relying on a normal approximation for the proportion's sampling distribution. This can be useful when data are sparse. The registry does not report the success count or evaluable denominator, so neither the estimate nor its exact interval can be reconstructed. No recalculated result is available in the registry record.

Why does censoring lead to a different method?

For a time-to-event outcome, a participant may have follow-up that ends before the endpoint status at 18 months is known. Such follow-up is censored: the participant contributes information up to the last point at which status is known, but is not automatically classified as either a success or a failure at the later time. The registry says that if participants are censored before 18 months, a Kaplan-Meier estimate of PFS18 with 95% confidence intervals will be reported.

In general, Kaplan-Meier estimation uses the timing of events and the follow-up available before censoring to estimate the event-free experience over time. Its interpretation depends on assumptions, including that censoring does not systematically remove participants with a different underlying event risk, after accounting for the information used in the analysis. If that assumption is not plausible, the estimate may be biased. The registry record does not report how much censoring occurred, why participants were censored, or whether the Kaplan-Meier method was ultimately used.

What can a single-group estimate establish?

A proportion or Kaplan-Meier estimate can describe the outcome observed in the enrolled group. Without a comparator, it does not estimate a treatment effect as a contrast between groups. General statistical reasoning distinguishes an outcome rate within a treatment group from the effect of treatment: the latter requires a credible counterfactual comparison, which this single-group design does not supply. Historical or external comparisons can be informative in some contexts, but differences in eligibility, care, follow-up, and outcome measurement can complicate interpretation. A specific external comparison is not reported in the registry record.

Enrollment is 8. General statistical reasoning indicates that estimates based on a small group are sensitive to the outcomes of individual participants, and uncertainty can be substantial. The exact width of uncertainty depends on the outcome data and analysis; it cannot be inferred from enrollment alone. Because the registry does not give the PFS18 estimate, evaluable denominator, or confidence interval, no numerical statement about precision is warranted.

How should planning calculations be distinguished from results?

The stated planning illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. The registry describes these as planning illustrations computed from the observed effect, not as the trial's own design. Such illustrations are hypothetical inputs for planning a future comparison. They are not observed outcomes, and they are not observed power for this study. The registry does not report its sample-size justification or the full statistical plan. Since this trial is single-group, an equal-allocation two-arm planning assumption should not be mistaken for the design actually used.

In general, a planned power calculation asks how often a design would detect a specified effect under stated assumptions. It does not tell readers the probability that a result is true, and it does not measure how informative the completed study's result is. The latter depends on the observed estimate and its uncertainty. Neither an observed PFS18 estimate nor a reported analysis is available in the registry record, so the primary outcome cannot be statistically evaluated from the endpoint description alone.

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("Treatment (Ixazomib, Pomalidomide, Dexamethasone, ")
n      <- c(8)
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  Treatment (Ixazomib, Pomalidomide, Dexamethasone,   8  0  0.0  0.0  36.9  0.0  32.4  0.3  33.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists secondary outcomes that include a VGPR rate, adverse events, overall response rate, and the percentage of patients alive at 30 months. The primary endpoint is PFS18. The registry record does not report a multiplicity adjustment, a hierarchy for testing outcomes, or a plan for controlling the chance of false-positive findings across multiple statistical tests. It also lists 0 analyses. The presence of several outcomes does not establish that formal hypothesis tests were conducted.

In general, multiplicity matters when several outcomes or comparisons are tested: interpreting each test as if it were the only test can make chance findings more likely across the full set. A prespecified hierarchy or an adjustment can address some multiplicity concerns. The actual approach for this trial is not reported in the registry record, so no claim about adjustment or confirmatory status is justified.

The primary endpoint description refers to evaluable patients, but the criteria for being evaluable and the analysis population are not reported in the registry record. The record does not state how missing endpoint assessments, withdrawals, or incomplete follow-up were handled, apart from the stated use of Kaplan-Meier estimation if participants are censored before 18 months. Censoring is not the same as treating an unknown outcome as a success or failure; its handling depends on follow-up and the analysis method.

The record also does not report whether interim analyses were planned or conducted, or provide a full statistical analysis plan. These omissions limit assessment of outcome selection, analysis-population definitions, and the handling of incomplete data. They do not demonstrate that any particular method was or was not used outside what is stated in the registry record.

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: anemia (12.5%), blood and lymph sys disorders - oth spec (12.5%), febrile neutropenia (12.5%), fever (12.5%), alkaline phosphatase increased (12.5%).

The registry lists the treatment group as having 8 participants at risk for serious adverse events and 4 affected. For other adverse events, it lists 8 at risk and 8 affected. It also lists 2 deaths. These are counts recorded for the study group; the registry information does not establish that the treatment caused an adverse event or death. The timing and causes of the deaths are not reported in the registry record.

The serious adverse event terms shown include anemia, blood and lymph sys disorders - Oth Spec, febrile neutropenia, fever, alkaline phosphatase increased, and platelet count decreased. Each term is listed as 12.5%. These percentages should be read as registry-reported values, not as an estimate of comparative risk. The record does not report the event-level detail needed to determine whether a participant experienced more than one listed term, how long events lasted, or whether events resolved.

In general, safety counts describe events or participants under the registry's reporting definitions; they do not by themselves establish causality. Interpretation also depends on definitions, observation time, seriousness criteria, and completeness of reporting. Further details on attribution and event timing are not reported in the registry record.

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

The registry record identifies a phase II investigation of a treatment sequence for relapsed or refractory multiple myeloma and defines a primary endpoint at 18 months. It also reports enrollment and selected adverse-event counts. These registry entries describe the study's purpose, design, and some recorded safety information. They do not provide the numerical PFS18 result needed to assess the primary endpoint.

Because the trial has a single group, it cannot directly estimate how the treatment program compares with another approach. A within-group estimate, if reported, would describe the outcome among participants enrolled in the study. It would not isolate the effect of treatment from the natural course of disease, participant selection, other care, or other influences. The registry record does not report a randomized comparison.

The safety counts warrant the same distinction between observation and attribution. The record lists participants affected and serious event terms, but does not say whether the events were judged related to treatment, when they occurred, or how they resolved. The deaths listed are not, by themselves, evidence about cause or treatment effect.

The absence of numerical primary and secondary outcome results in the registry record is not evidence of either benefit or lack of benefit. It also prevents assessment of the estimate's precision. Enrollment of 8 is relevant context for how much information might be available, but it cannot replace the missing endpoint count, estimate, or confidence interval. The study's completed status indicates that the registry marks it completed; it does not supply results.

Accordingly, the defensible interpretation is limited: the trial was a small, single-group phase II study with a specified PFS18 endpoint and reported safety counts, while the primary efficacy result and detailed analyses are not reported in the registry record. Any stronger conclusion would require outcome and analysis information not reported there.

14. Why This Trial Matters Statistically

This trial illustrates why a registry description and a registry result are different kinds of evidence. The record specifies a clinically interpretable endpoint, PFS18, and outlines how the proportion and its uncertainty were intended to be estimated. Yet without the numerical estimate, evaluable denominator, and confidence interval, readers cannot judge the observed outcome or its precision. A complete endpoint definition is useful, but it is not a substitute for the result.

The design also shows the limits of single-group evidence. A treatment sequence can be described in detail while still leaving the comparative question unanswered. Without a concurrent comparator, outcome estimates cannot separate the treatment program's effect from other influences on the observed course. This distinction is central to interpreting phase II studies, which may characterize activity and inform future research but do not automatically support causal comparisons.

The record's safety counts provide another statistical lesson: counts and listed percentages need context. Attribution, follow-up, event definitions, and the relation between individual events are important for interpretation, but these details are not reported in the registry record. The listed numbers should therefore be read descriptively rather than as comparative evidence.

Finally, planning calculations should remain separate from observations. The record describes planning assumptions based on an observed effect, but those illustrations do not constitute the study's original design rationale or observed power. This trial's own sample-size justification is not reported in the registry record. Separating design assumptions, observed results, and uncertainty helps prevent planning concepts from being mistaken for evidence about the completed study.

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.

Several trial-specific limitations constrain statistical interpretation. The registry lists enrollment of 8 and a single treatment group, so the study offers no concurrent randomized comparison. Any outcome estimate would describe this enrolled group rather than establish a treatment contrast. The registry record does not report participant characteristics in enough detail to assess representativeness or the applicability of results to other populations.

The primary endpoint's numerical result is not reported in the registry record. The PFS18 estimate, 95% confidence interval, success count, and evaluable denominator are all absent from the information available. The handling of censoring is described conditionally, but the amount and pattern of censoring and the method ultimately used are not reported. Eligibility for the evaluable population and handling of other missing assessments are also not reported in the registry record.

The treatment description gives an induction schedule, while complete details of the post-transplant treatment sequence are not reported in the registry record. The registry lists selected safety counts and terms but does not report event timing, duration, outcome, or attribution. The cause and timing of the listed deaths are not reported.

Finally, the registry record does not report the sample-size justification, full statistical analysis plan, multiplicity approach, or whether interim analyses were planned or conducted. These omissions limit assessment of the intended analysis and the context of any results. They should be treated as unreported information, not as proof that a method was absent from study conduct.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Ixazomib Citrate, Pomalidomide, Dexamethasone, Stem Cell Transplant in Treating Relapsed or Refractory Multiple Myeloma — NCT03202628.
• Registry record last updated 2023-09-21; status last verified 2023-09.
• Results first posted 2022-05-19.
• 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

NCT03202628 is a completed phase II, single-group study sponsored by Mayo Clinic in recurrent or refractory plasma cell myeloma. Enrollment is 8. The registered intervention combines ixazomib, pomalidomide, dexamethasone, and autologous hematopoietic stem cell transplantation. The primary endpoint is the proportion alive and free from disease progression at 18 months from study entry, with exact binomial confidence intervals and Kaplan-Meier estimation specified for censoring before 18 months.

The registry lists 7 outcome measures and 0 analyses. It reports selected adverse-event counts and terms, but the numerical primary endpoint result and detailed analysis information are not reported in the registry record. The single-group design does not provide a concurrent comparator, limiting comparative interpretation.