Dendritic Cell/Myeloma Fusion Vaccine for Multiple Myeloma (BMT CTN 1401): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dendritic Cell/Myeloma Fusion Vaccine for Multiple Myeloma (BMT CTN 1401) (NCT02728102), a randomized phase 2 study. The primary outcome is Percentage of Participants With 1-year Response Rate of CR/sCR.

2. Clinical Question

The trial’s stated hypothesis was that adding the vaccine would improve response after autologous transplant. The primary endpoint therefore focuses on a defined response state at a specified follow-up time, rather than response alone: participants also had to be alive. The registry reports 52.9% for the vaccine group and 50.0% for the combined lenalidomide-with-or-without-GM-CSF group. These are observed proportions, not a guarantee about the result in other participants or settings. The comparison is uncertain, as reflected in the confidence intervals and the reported test result. The registry record does not report a separate primary comparison of the vaccine group against each non-vaccine group individually; it identifies the combined non-vaccine comparison as the primary analysis.

3. Trial Design

This was a completed, randomized, open-label, parallel-group Phase II trial sponsored by the National Heart, Lung, and Blood Institute. The registry lists enrollment as 203 and the condition as multiple myeloma. The study began in 2016-07, and primary completion is listed as 2020-06-30.

All three arm descriptions include tumor cell collection and autologous stem cell transplant with melphalan. The vaccine arm then included leukapheresis, lenalidomide maintenance, myeloma vaccine, and GM-CSF. A second arm received lenalidomide maintenance with GM-CSF, and a third received maintenance lenalidomide without GM-CSF. The primary analysis combined the two non-vaccine arms for comparison with the vaccine arm. The reported primary results list 68 participants in each of those analysis groups.

Randomization is reported, but the allocation ratio, sequence-generation method, concealment procedures, and stratification factors are not reported in the registry record. Masking is listed as none. The registry record does not report the trial’s original sample-size justification, the assumptions used in its design, or whether interim analyses were planned or conducted. Those omissions limit assessment of how the study was planned and how the posted analyses relate to any prespecified plan.

The study included 15 outcome measures and 40 analyses in the record. The primary outcome was the percentage of participants alive in complete response or stringent complete response at one year. Secondary outcomes included treatment response, myeloma progression, treatment-related mortality, progression-free survival, and overall survival. The record identifies several outcomes as pairwise analyses, but detailed results are not available for every outcome named in the registry.

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: Sixty-three participants dropped out of the study prior to randomization and 140 participants received a transplant and proceeded to randomization. The reasons for dropout include insufficient tumor cells collected (n=13), withdrew consent from study (n=12), ineligible to be randomized (n=8), disease progression prior to randomization (n=6), refused or did not make it to transplantation (n=10), physician decision (n=7), manufacturing failure (n=4), lost to follow up (n=2), and insurance (n=1).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The primary analysis population includes all the randomized participants. Protocol defines primary analysis is to compare participants receiving vaccine vs those without vaccine. So no vaccine arms with or without GM-CSF are combined. Four participants withdrew consent to all study procedures before 1-year post-transplant. Of these, 2 cases on the Lenalidomide/GM-CSF arm and 2 cases on the Lenalidomide Alone arm. These participants were not evaluable for the primary endpoint and ERC confirmed.

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 Percentage of Participants With 1-year Response Rate of CR/sCR, measured over 1 year.

The primary endpoint is the percentage of participants alive and in complete response (CR) or stringent complete response (sCR) at one year after transplant. Requiring participants to be alive makes the endpoint a combined status measure: being in CR or sCR alone is not enough if a participant is not alive at the assessment point.

CR requires absence of the original monoclonal paraprotein in serum and urine by routine electrophoresis and immunofixation; less than 5% plasma cells in a bone marrow aspirate and also on trephine bone biopsy, if performed; no increase in the size or number of lytic bone lesions on radiological investigations; and disappearance of soft tissue plasmacytomas. The registry defines sCR as meeting CR criteria and also having a normal free light chain ratio and no clonal cells in bone marrow by immunohistochemistry or immunofluorescence.

A response endpoint is used to assess disease status at a specified follow-up time. Combining CR and sCR makes the primary measure the proportion reaching either of those response categories while alive. It does not describe the timing of response, the duration of response, or every aspect of subsequent disease course. The registry reports the primary endpoint as a percentage and gives an 80% confidence interval for each group. The registry record does not report further details about assessment schedules, adjudication, or handling of participants whose response status was unavailable.

7. Results Posted in the Registry

• Lenalidomide With or Without GM-CSF: 50.0% (34/68) versus 52.9% (36/68) on control; risk difference -2.9 percentage points (95% CI -19.7 to 13.9), risk ratio 0.94 (0.68–1.31); unadjusted two-proportion z-test p = 0.731.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Percentage of Participants With Myeloma Progression of Vaccine and Non-vaccine Arms

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Lenalidomide With or Without GM-CSF: 11.1% (8/72) versus 20.6% (14/68) on control; risk difference -9.5 percentage points (95% CI -21.5 to 2.6), risk ratio 0.54 (0.24–1.20); unadjusted two-proportion z-test p = 0.124.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Lenalidomide With or Without GM-CSF and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of Participants With Myeloma Progression in Pairwise Analysis

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Lenalidomide and GM-CSF: 8.1% (3/37) versus 20.6% (14/68) on control; risk difference -12.5 percentage points (95% CI -25.5 to 0.5), risk ratio 0.39 (0.12–1.28); unadjusted two-proportion z-test p = 0.097.
  • Maintenance Lenalidomide: 14.3% (5/35) versus 20.6% (14/68) on control; risk difference -6.3 percentage points (95% CI -21.4 to 8.8), risk ratio 0.69 (0.27–1.77); unadjusted two-proportion z-test p = 0.435.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Lenalidomide and GM-CSF and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Maintenance Lenalidomide and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of Participants With Progression-Free Survival

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Lenalidomide With or Without GM-CSF: 88.9% (64/72) versus 79.4% (54/68) on control; risk difference 9.5 percentage points (95% CI -2.6 to 21.5), risk ratio 1.12 (0.97–1.30); unadjusted two-proportion z-test p = 0.124.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Lenalidomide With or Without GM-CSF and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes extend the assessment beyond the one-year response endpoint to disease progression, progression-free survival, overall survival, treatment-related mortality, and other response measures. The posted estimates for the progression-related outcomes do not form a uniformly favorable pattern for the vaccine comparison: the direction of the progression estimate is reflected in the corresponding progression-free survival estimate, while the time-to-event tests do not show a clear separation. Pairwise progression comparisons also vary according to which non-vaccine arm is used.

These outcomes add context but do not overturn or replace the primary result. Response at one year, progression by a later follow-up point, and progression-free survival capture different aspects of the clinical course. Their estimates may differ in direction or precision without being logically inconsistent. The registry record includes overall survival among the named outcomes, but detailed overall-survival results are not reported in the posted outcome details available for this record.

Secondary analyses usually carry less weight than a prespecified primary analysis because many endpoints and comparisons create more opportunities for chance findings. The registry lists 15 outcome measures and 40 analyses, but a multiplicity adjustment or hierarchy for interpreting them is not reported in the registry record. Without such a strategy, secondary p-values should not be treated as if each were an independent confirmatory test. Their best role is to describe patterns, help identify questions for further study, and show whether outcome estimates broadly align with the primary result.

The secondary results also have different methods and follow-up definitions. Percentage outcomes, cumulative-incidence comparisons, and time-to-event analyses answer related but nonidentical questions. They should be interpreted using their own endpoint definitions and uncertainty, rather than combined into a single summary of treatment effect.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Participants Response to Treatment
• Percentage of Participants With Myeloma Progression of Vaccine and Non-vaccine Arms
• Percentage of Participants With Myeloma Progression in Pairwise Analysis
• Percentage of Participants With Treatment-related Mortality (TRM)
• Percentage of Participants With Progression-Free Survival
• Percentage of Participants With Progression-Free Survival in Pairwise Analysis
• Percentage of Participants With Overall Survival
• Percentage of Participants With Overall Survival in Pairwise Analysis

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is binary at the participant level: each participant either meets the definition of alive in CR or sCR at one year or does not. A percentage summarizes the share meeting that definition in each analysis group. It is an estimate from the participants included in that group, and its precision depends in part on the amount of information available and the number of observed outcomes.

What the confidence intervals express

A confidence interval describes a range of values compatible with the observed data under the statistical procedure used. It reflects uncertainty in the estimate; it is not a guarantee that the true value lies in that particular interval, nor is it the probability that a specific treatment effect is correct. A wider interval indicates less precision than a narrower interval. The primary arm percentages are accompanied by 80% confidence intervals in the registry. The recalculated risk difference uses a 95% confidence interval, so its interval should not be compared directly with the sponsor’s 80% interval as if they had the same coverage.

The sponsor’s primary analysis is reported as a Z test of the difference in proportions. This compares the observed proportions using a test statistic and reports an estimate, confidence interval, and p-value. The p-value describes how compatible the data are with the test’s null model, given its assumptions; it is not the probability that the null hypothesis is true. It also does not measure the clinical importance of an effect.

How the recalculation differs

The recalculated comparison is an unadjusted risk difference based on posted summary counts. It contrasts the non-vaccine group with the vaccine group and does not adjust for other variables or account for any stratification. Its estimate is -0.029, with a 95% confidence interval from -0.197 to 0.139 and p = 0.731. This is a simple recalculation, not a replacement for the trial’s own analysis. It uses a different confidence level from the sponsor’s reported primary result, which is one reason to read the two analyses as distinct presentations rather than as identical tests.

The registry also reports a Cochran-Mantel-Haenszel analysis for an odds ratio as an equivalence analysis. This method can combine information across strata when a stratified comparison is relevant. The reported odds ratio is 1.19, with an 80% confidence interval from 0.70 to 2.03 and p = 0.746. An equivalence analysis asks whether the data support a difference within a prespecified equivalence margin. The margin and its justification are not reported in the registry record, so the result cannot be fully interpreted as evidence of equivalence from the posted information alone.

Methods used for secondary outcomes

For myeloma progression, the registry reports Gray’s test for cumulative incidence. This approach is used when estimating an event’s cumulative incidence in the presence of competing events, which can prevent the event of interest from occurring. In general, treating competing events as though they were ordinary non-informative censoring can misrepresent cumulative incidence. The registry’s record does not provide further detail about competing-event definitions or all analytic choices.

For progression-free survival, the registry reports a log-rank test. In general, the log-rank test compares event-time patterns over follow-up, accounting for the timing of events and censoring. Its interpretation depends on the survival-analysis setup, including how events and censoring are defined. Those details are not fully reported in the registry record. A percentage at a particular time and a time-to-event test answer related but different questions: the former describes status at a time point, while the latter evaluates the pattern of times to events over follow-up.

The registry’s posted secondary analyses also include Z tests for differences in proportions. Their estimates and p-values should be read in the context of their specific endpoints and comparisons. A general statistical caution is that many outcomes and comparisons create multiple opportunities for apparently notable results. Without a reported multiplicity strategy, isolated secondary p-values should be treated as exploratory rather than as definitive evidence.

General statistical methods explain how estimates and tests are constructed; they do not supply missing protocol information. The registry record does not report the full statistical analysis plan, the handling of missing data, the randomization stratification, or the complete details needed to reproduce every analysis.

11. Confidence Intervals and Precision

The primary group estimates have 80% confidence intervals: 44.5% to 61.3% for the vaccine group and 41.6% to 58.4% for the combined non-vaccine group. Their breadth shows that the observed proportions are not estimated with high precision. The ranges overlap, and the registry’s reported difference interval, from -8.8 to 14.6, includes values below and above no difference. The posted primary estimate therefore leaves considerable uncertainty about both the direction and magnitude of the group contrast.

The recalculated risk difference has a 95% confidence interval from -0.197 to 0.139. A difference interval that includes zero is compatible with no difference as well as with differences in either direction under the method used. This does not prove equality; it indicates that the data do not narrowly determine the contrast. The recalculated interval has a different confidence level and scale from the sponsor’s reported 80% interval.

Secondary outcomes use 95% confidence intervals for the reported percentages. Those intervals also show uncertainty in the outcome estimates, and their precision varies by endpoint and analysis group. A confidence interval is not a substitute for the endpoint definition, follow-up information, or analysis method. For time-to-event comparisons, the registry reports p-values but does not provide a confidence interval for the test result in the listed analysis.

Precision is distinct from statistical significance and from clinical importance. The registry record does not report a threshold for a clinically important difference in the primary outcome. Without such a threshold, the interval’s width can describe statistical uncertainty, but it cannot by itself determine whether any plausible effect would matter clinically.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations calculated from the observed effect, not the trial’s original sample-size calculation. For the binary outcomes, the listed figures are participants per arm. For time-to-event outcomes, the figures are total events. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect.

The 80% power column represents the number of participants per arm that the planning calculation would require to have an 80% chance of detecting the stated effect under those assumptions, if that effect were the true one. The 90% power column represents the corresponding planning target for a 90% chance. Higher planned power generally requires more information, and the table shows that planning for a smaller fraction of the observed effect requires more participants. The rows labelled as fractions of the observed effect are alternative planning scenarios, not additional observed trial results.

These figures do not indicate the probability that the trial result is correct, and they do not measure the power actually achieved by the completed trial. This is not observed power. The registry record does not report the original design assumptions or sample-size justification, so these planning figures should not be read as a reconstruction of the trial’s intended design.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.529; treatment proportion p₁ = 0.500; average p̄ = 0.515.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7068 = 1.3853.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.7065 = 0.5946.
4. n = (1.3853 + 0.5946)² / (-0.0294)² = 4,531.5, rounded up to 4,532 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.529411764705882                          # control proportion
p1 <- 0.5                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(2728102)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 4,532 (80% power), 6,066 (90% power)
 75% of observed effect: n per arm = 8,054 (80% power), 10,781 (90% power)
 50% of observed effect: n per arm = 18,111 (80% power), 24,244 (90% power)
power.prop.test: 4531.5 
Simulated power at n = 4,532 per arm: 0.796 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry’s reported primary analysis is the sponsor’s trial analysis: a Z test of the difference in proportions. It gives a difference of 2.9, an 80% confidence interval from -8.8 to 14.6, and p = 0.366. The arm percentages reported alongside it are 52.9% for lenalidomide, vaccine, and GM-CSF and 50.0% for lenalidomide with or without GM-CSF.

The recalculation is a separate, unadjusted analysis from the posted summary statistics. It gives a risk difference of -0.029 for the non-vaccine group relative to the vaccine group, with a 95% confidence interval from -0.197 to 0.139 and p = 0.731. Its direction is expressed in the reverse order, and its confidence level differs from the sponsor’s reported interval. The calculations are therefore not exact like-for-like presentations.

The registry does not flag a discrepancy between the posted result and the recalculation. The sponsor’s analysis remains the trial’s own reported analysis; the recalculation provides a transparent supplementary summary, not a correction or a substitute for the trial analysis. Neither analysis yields a narrow estimate of the primary contrast.

15. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary endpoint and a primary comparison: the proportion alive in CR or sCR at one year, comparing the vaccine group with the combined non-vaccine groups. It also lists numerous secondary outcomes and analyses, including separate pairwise comparisons. The registry record does not report a complete statistical analysis plan describing an outcome hierarchy, multiplicity adjustment, or rules for interpreting multiple tests.

Multiplicity matters because testing many outcomes or contrasts increases the chance that some result will appear unusual under a no-effect model, even if no single effect is established. This general concern does not mean a secondary result is false; it means isolated secondary findings need cautious interpretation, especially when the analysis plan and adjustment strategy are unavailable. Secondary p-values should be considered alongside estimates, confidence intervals, endpoint relevance, and consistency across analyses.

The primary population is described as all randomized participants. The registry description also notes that four participants withdrew consent to all study procedures, but the timing and treatment of these withdrawals in the analysis are not reported in the registry record. The record does not explain how missing response assessments, incomplete follow-up, or other unavailable outcome data were handled. It also does not report whether the analyses followed intention-to-treat principles in all operational details or used any imputation or sensitivity analyses.

These omissions make it difficult to assess whether missingness could have influenced the posted estimates or whether the listed analysis population was implemented as planned. Randomization supports a comparison by assigned group when analyzed appropriately, but it does not itself resolve missing outcomes or the consequences of departures from assigned treatment. The registry record does not report enough information to assess those issues fully.

16. 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: atrial flutter (2.9%), congestive heart failure (2.7%), melanoma (2.7%), liver function tests increased (2.7%), neutropenic fever (1.5%).

The registry lists serious adverse event counts separately by arm: 2 participants in the vaccine, lenalidomide, and GM-CSF group; 3 in the lenalidomide-and-GM-CSF group; and 1 in the maintenance-lenalidomide group. The corresponding numbers at risk are 68, 37, and 35. These are counts as posted, not a complete comparative safety analysis. The other adverse event counts listed are 3, 3, and 3 for those same groups, with the same respective numbers at risk.

The registry also lists serious event terms and percentages, including atrial flutter at 2.9%, congestive heart failure at 2.7%, melanoma at 2.7%, liver function tests increased at 2.7%, neutropenic fever at 1.5%, and prolonged QTc at 1.5%. These entries describe reported events; they do not establish that a treatment caused them. The record does not provide enough information to assess exposure duration, event severity distributions, or adjusted between-group safety differences.

Deaths are listed as 3, 0, and 1 across the same three adverse-event groups. Those counts should not be assumed to represent treatment-related deaths: the record lists treatment-related mortality as a secondary outcome, but the death counts alone do not identify cause or attribution.

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

The registry results show that the observed one-year proportions meeting the primary response definition were similar in the reported analysis groups: 52.9% in the vaccine group and 50.0% in the combined non-vaccine group. The estimated contrast is imprecise. The sponsor’s reported confidence interval spans values on either side of no difference, and the recalculated interval does as well. The posted data therefore do not establish a clear difference in the primary endpoint.

This does not prove that the groups are equivalent. A result that does not demonstrate a difference is not the same as evidence that any difference is negligibly small. Equivalence requires a defined margin and an analysis designed to evaluate that margin; the registry record does not report a margin for the primary comparison. The separate equivalence analysis listed for an odds ratio does not supply the missing details needed to make a broader claim about equivalence.

The endpoint is also specific: it records alive in CR or sCR at one year after transplant. It is not a complete measure of long-term disease control, quality of life, treatment burden, or every outcome important to participants. Secondary progression and survival outcomes offer additional perspectives, but their posted results have their own uncertainty and do not all show the same pattern.

The results apply to the trial population and the treatment approaches described in the registry. They should not be generalized automatically to different populations, treatment schedules, or clinical settings. The registry record does not report key details such as the full analysis plan and handling of missing outcomes, which limits how completely the posted results can be interpreted. No treatment recommendation follows from these statistics alone.

18. Why This Trial Matters Statistically

This trial raises a useful statistical question about how to evaluate an added intervention when the underlying care pathway already includes transplant and maintenance therapy. The primary comparison is not vaccine versus no treatment: both groups received autologous transplant and lenalidomide maintenance, while the vaccine group also received GM-CSF. The comparator combines lenalidomide maintenance with GM-CSF and lenalidomide maintenance alone. That structure matters when interpreting the contrast, because the primary result estimates the difference between the vaccine strategy and a pooled non-vaccine strategy, not the isolated effect of GM-CSF.

The endpoint also illustrates the importance of defining the target outcome precisely. Alive in CR or sCR at one year is a specific joint status, with explicit response criteria. It is not identical to response alone or to a time-to-event outcome. Keeping these distinctions clear helps prevent overinterpretation when results across response, progression, and survival measures do not align perfectly.

Finally, the registry presents both the trial’s reported analysis and a simple recalculation from summary data. Their different confidence levels, direction conventions, and methods make clear why analytical details matter when comparing estimates. Confidence intervals communicate uncertainty that a point estimate or p-value alone cannot. The missing statistical-plan and missing-data details also show why transparent reporting is important for interpreting randomized trials and assessing the strength of conclusions.

19. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The registry record does not provide the complete protocol or statistical analysis plan. In particular, the original sample-size justification, allocation ratio, randomization procedures, stratification factors, and interim-analysis plan are not reported. The sample-size figures associated with the posted results are planning illustrations based on observed effects, not the trial’s original design calculations.

The primary comparison pools the two non-vaccine groups, so it does not separately estimate the vaccine contrast against each maintenance strategy as the primary analysis. It also cannot isolate the contribution of GM-CSF within the pooled comparator. Although secondary pairwise progression analyses are listed, they do not resolve all the questions that a differently specified primary comparison might address.

There are limits to interpretation of the posted outcome data. The registry description mentions four consent withdrawals but does not provide a complete statement of their timing or how they were handled. Missing outcome data, censoring details, response assessment procedures, and sensitivity analyses are not fully described in the registry record. The record also does not report a primary clinically important difference or the equivalence margin needed to interpret the listed equivalence analysis.

The trial is open-label, with masking listed as none. The registry record does not describe whether response assessments were independently reviewed or otherwise protected from potential assessment bias. Multiple outcomes and analyses are listed, but a multiplicity strategy is not reported. These reporting limitations do not negate the randomized design, but they constrain assessment of the strength, robustness, and scope of the posted findings.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Dendritic Cell/Myeloma Fusion Vaccine for Multiple Myeloma (BMT CTN 1401) — NCT02728102.
• Registry record last updated 2024-05-07; status last verified 2024-05.
• Results first posted 2021-09-09.
• 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.

23. Record Summary

The registry record describes a completed, randomized, open-label, parallel-group Phase II trial of a dendritic cell/myeloma fusion vaccine with GM-CSF and lenalidomide maintenance after autologous transplant, compared with lenalidomide maintenance with or without GM-CSF. The primary endpoint was the percentage alive in CR or sCR at one year.

The posted primary proportions were 52.9% for the vaccine group and 50.0% for the combined non-vaccine group. The sponsor-reported difference had an 80% confidence interval spanning no difference; the unadjusted recalculation also had an interval spanning no difference. The registry therefore leaves substantial uncertainty about the size and direction of the primary contrast. Secondary analyses provide additional outcome-specific information, but the multiplicity plan and several analysis details are not reported in the registry record.