Study of Melphalan Flufenamide (Melflufen) + Dex With Bortezomib or Daratumumab in Patients With RRMM: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Melphalan Flufenamide (Melflufen) + Dex With Bortezomib or Daratumumab in Patients With RRMM (NCT03481556), a non-randomized phase 1, phase 2 study. The primary outcome is Phase 1: Number of Participants Who Experienced a Dose Limiting Toxicity (DLT).

2. Clinical Question

The study’s statistical question is therefore principally descriptive in the available record: what dose-limiting and serious adverse-event counts were recorded within each regimen group, and what can those counts establish? They can describe the groups as posted, but without randomized allocation they do not establish that a difference between groups was caused by the regimen. The record also does not provide estimates of comparative efficacy, uncertainty intervals, or adjusted analyses. The findings should be read as registry summaries of a nonrandomized study rather than as a definitive treatment comparison.

3. Trial Design

This was an open-label Phase 1/2a study of melflufen and dexamethasone with either bortezomib or daratumumab in patients with relapsed or relapsed-refractory multiple myeloma. The registry lists a parallel model and nonrandomized allocation. Participants and study personnel were not masked. The recorded enrollment was 56. The study status is terminated; the recorded start date is 2018-04-12 and primary completion date is 2022-02-02.

Regimen A combined melflufen with bortezomib and dexamethasone. Melflufen was described at 30 mg and 40 mg or 20 mg intravenously on Day 1 of each 28-day cycle. Bortezomib was 1.3mg/m² subcutaneously on Days 1, 4, 8 and 11. Dexamethasone was scheduled on those days, with an additional schedule on Days 15 and 22; the listed dose adjustments distinguish patients aged 75 years or older.

Regimen B combined melflufen with daratumumab and dexamethasone. Melflufen was described at the same listed dose levels and Day 1 schedule. Daratumumab was scheduled weekly for 8 doses, every other week for 8 doses, and then once every 4 weeks. Dexamethasone was listed as an oral weekly dose, with a lower listed dose for patients aged 75 years or older.

These are descriptions of treatment schedules, not evidence that all participants received every listed dose or completed every planned cycle. The registry record does not report the numbers treated at each dose level as an analysis population, reasons for discontinuation by regimen, or adherence to the planned schedules. Because allocation was not randomized, the groups cannot be assumed to have comparable baseline characteristics. Baseline comparability details and the method used to place participants into regimens are not reported in the registry record.

The primary endpoint belongs to Phase 1 and concerns dose-limiting toxicity during Cycle 1. Secondary outcomes include best response, duration of response, time to response, progression-free survival, overall survival, duration of clinical benefit, time to progression, and clinical benefit rate. Although the registry lists 12 outcome measures, the posted record reports zero analyses. Numerical results for these outcomes 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: A total of 56 participants were enrolled in the study, all of whom received study treatment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Only participants included in the DLT Analysis set were included in this analysis. The DLT Analysis Set was defined as all participants in Phase 1 that complete Cycle 1 of therapy or are discontinued due to a DLT event.

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.

Population: Participants included in the Safety Analysis Set were included in the Baseline Characteristics. The Safety Analysis Set includes all patients that have received at least 1 dose (or partial dose) of melflufen, dexamethasone, or partner therapy (bortezomib or daratumumab).

6. Primary Endpoint

The registry lists the primary outcome as Phase 1: Number of Participants Who Experienced a Dose Limiting Toxicity (DLT), measured over Cycle 1: Day 1 to Day 28.

The Phase 1 primary endpoint is the number of participants who experienced a dose-limiting toxicity during Cycle 1, defined as Day 1 to Day 28. The registry states that toxicity was graded using the National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.03. The listed criteria cover specified severe non-hematologic toxicities, severe thrombocytopenia or neutropenia, and toxicity-related delay in starting the next cycle. Some criteria depend on whether toxicity prevents administration of > 1 dose of bortezomib or daratumumab; others specify blood-count thresholds, duration, bleeding, or delay.

As a general statistical concept, a dose-limiting toxicity endpoint helps early-phase studies describe whether a regimen has toxicities meeting prespecified severity and timing criteria. Restricting the window to Cycle 1 creates a defined period for classifying the endpoint, although events outside that period are not captured by this particular measure. The endpoint is a participant count, not a measure of the total number of adverse events or the severity of every event experienced.

The analysis population is defined as Phase 1 participants who completed Cycle 1 or were discontinued because of a dose-limiting toxicity. This definition includes participants who stop because of the event being assessed. The registry record does not report the numerical primary endpoint result, the number included in the DLT analysis set, or a confidence interval. The endpoint definition is available, but its observed value and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a Phase 1/2a, open-label, parallel study with nonrandomized allocation. It does not report a detailed statistical analysis plan, inferential model, or method for adjusting comparisons. The following statistical explanations are general; they do not describe analyses claimed by the registry.

What does nonrandomized allocation imply?

In a randomized study, assignment by chance is intended to balance measured and unmeasured participant characteristics across groups on average. In a nonrandomized study, treatment assignment may be related to clinical features, physician decisions, dose-escalation considerations, or other factors. If those factors also relate to safety or efficacy outcomes, group differences may be confounded. This does not mean that a particular bias occurred in this study; it means that a difference between groups cannot automatically be attributed to treatment. The allocation procedure and any adjustment strategy are not reported in the registry record.

Open-label treatment means masking was not used. As a general matter, awareness of treatment can influence reporting, clinical management, or assessment of outcomes, particularly for outcomes involving judgment. Objective laboratory thresholds may be less subjective than some clinical assessments, but the registry’s full procedures for assessment and adjudication are not reported. No conclusion about actual assessment bias can be drawn from the open-label designation alone.

How should a participant count be read?

The primary endpoint is a count of participants meeting a dose-limiting toxicity definition within a specified treatment window. A participant-based endpoint classifies whether a person meets the criteria; it is different from counting every event, measuring time until an event, or measuring the total duration of toxicities. The eligibility definition for the DLT analysis set includes participants who completed Cycle 1 or were discontinued because of a DLT. The size and observed event count for that analysis set are not reported in the registry record.

For a binary outcome, a proportion is often used to describe the number with an event relative to the number assessed. A confidence interval can express the uncertainty around an estimated proportion. In general, intervals are wider when information is sparse and narrower when information is more precise. The registry record does not give a primary endpoint estimate or interval, so its precision cannot be assessed from that endpoint. The serious adverse-event summaries provide group counts and at-risk counts, but no uncertainty intervals or inferential comparisons.

Why do event definitions and time windows matter?

A prespecified toxicity definition determines which events count toward the primary endpoint. Here, the registry identifies grading criteria and a Cycle 1 window, as well as criteria involving non-hematologic toxicity, platelet and neutrophil thresholds, clinically significant bleeding, and delay to the next cycle. Applying consistent rules is important because a different threshold or observation window can change which participants qualify as having the endpoint. The registry gives the criteria, but does not report adjudication procedures or the handling of incomplete assessments.

Time-to-event outcomes such as progression-free survival, overall survival, duration of response, time to response, and time to progression require information about event times and follow-up. General methods for these outcomes must account for participants who have not experienced the event by the end of observation, often described as censoring. The registry record lists these outcomes but does not report their estimates, follow-up summaries, censoring rules, or analysis methods. No specific time-to-event method can therefore be attributed to the study from this record.

What does the planning illustration represent?

The sample-size material is described as a planning illustration computed from the observed effect, not as the trial’s own design. Its stated assumptions are 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. For time-to-event outcomes, the stated planning quantity is the total number of events using the Schoenfeld approach; other outcomes use participants per arm. These are planning assumptions, not observed power and not evidence that the trial was designed around those assumptions. The underlying observed effect and numerical planning results are not reported in the registry record, so no planning estimate can be independently interpreted from the details.

As a general concept, over-dispersion arises when count variability exceeds what a simple model assumes. If a count outcome were analyzed using a model that assumed less variability than is present, uncertainty could be understated. The registry record does not report a count model or an over-dispersion assessment, and the participant-count primary endpoint does not itself establish that such a model was used. This concept is relevant only as a general consideration, not as a description of this study’s analysis.

What is missing from the inferential record?

The registry reports zero analyses. It does not report p-values, confidence intervals, adjusted effects, or a statistical model for the primary or secondary outcomes. The planned or performed approach to interim analyses, hypothesis testing, and handling of multiple outcomes is not reported in the registry record. Without those details and numerical outcome estimates, readers cannot assess the strength or precision of an efficacy comparison. The posted safety counts can be read descriptively, with the limitations imposed by nonrandomized allocation and absent uncertainty estimates.

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("Regimen A - Melflufen 30mg + Bortezomib + Dexameth", "Regimen A - Melflufen 40mg + Bortezomib + Dexameth", "Regimen B - Melflufen 30mg + Daratumumab + Dexamet", "Regimen B - Melflufen 40mg + Daratumumab + Dexamet")
n      <- c(6, 6, 3, 6)
events <- c(0, 0, 0, 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  Regimen A - Melflufen 30mg + Bortezomib + Dexameth  6  0  0.0  0.0  45.9  0.0  39.0  0.4  41.0
ARM  Regimen A - Melflufen 40mg + Bortezomib + Dexameth  6  0  0.0  0.0  45.9  0.0  39.0  0.4  41.0
ARM  Regimen B - Melflufen 30mg + Daratumumab + Dexamet  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2
ARM  Regimen B - Melflufen 40mg + Daratumumab + Dexamet  6  0  0.0  0.0  45.9  0.0  39.0  0.4  41.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists several secondary outcomes, including response, duration of response, time to response, progression-free survival, overall survival, duration of clinical benefit, time to progression, and clinical benefit rate. It also lists 12 outcome measures in total. The record reports zero analyses, so it does not provide numerical results for those secondary outcomes or explain whether they were tested as a family of hypotheses.

As a general statistical concept, testing many outcomes can increase the chance of at least one apparently notable result arising by chance. A multiplicity strategy may control that risk, prioritize outcomes, or define a hierarchy of tests. The registry record does not report whether any such strategy was planned or used, nor does it describe interim analyses or stopping boundaries. No multiplicity adjustment should be assumed.

Missing-data handling is also not reported in the registry record. The DLT analysis set is defined as Phase 1 participants who completed Cycle 1 or discontinued because of a DLT, but the record does not state how other incomplete Cycle 1 assessments were handled, whether any endpoint data were imputed, or whether sensitivity analyses were performed. The broader analysis populations for secondary outcomes are not reported in the registry record.

These omissions limit interpretation: without denominators and missing-data rules for each endpoint, it is difficult to determine exactly who contributed to each estimate; without a multiplicity plan, confirmatory meaning cannot be assessed; and without analysis populations, results cannot be matched to clearly defined groups. Because numerical secondary analyses are not reported, these concerns cannot be resolved from the posted 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: influenza (33.3%), pneumonia (16.7%), covid-19 pneumonia (16.7%), sepsis (16.7%), febrile neutropenia (16.7%).

The serious adverse-event summaries are presented separately for four regimen and dose groups. The registry lists 9 affected participants among 15 at risk for A (Melflufen+Bortezomib+Dex) 30 mg, 5 among 8 for A 40 mg, 4 among 6 for B (Melflufen+Daratumumab+Dex) 30 mg, and 11 among 27 for B 40 mg. These are descriptive counts, not adjusted estimates or randomized comparisons.

The listed death counts are 4, 2, 3, and 16 in those respective groups. The record does not establish from these counts whether a death was related to treatment. The timing, causes, and attribution details are not reported in the registry record.

The registry also identifies influenza at 33.3% and pneumonia, COVID-19 pneumonia, sepsis, febrile neutropenia, and humerus fracture at 16.7% each among the top serious adverse-event terms. The denominator for those percentages is not reported in the registry record. A term percentage should not be interpreted as the risk for an individual participant unless its denominator and event-counting method are known. Serious adverse-event counts and the primary dose-limiting toxicity endpoint are distinct summaries; the posted record does not provide the primary endpoint result.

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

The record establishes that an open-label, nonrandomized Phase 1/2a study evaluated melflufen and dexamethasone in combination with bortezomib or daratumumab in patients with relapsed or relapsed-refractory multiple myeloma. It defines a Phase 1 primary endpoint based on dose-limiting toxicity during Cycle 1 and gives criteria for classifying that endpoint. It also posts serious adverse-event counts by regimen and dose group.

Those safety counts describe what the registry lists for each group. They do not, by themselves, demonstrate that one regimen caused more or fewer adverse events than another. Nonrandomized groups may differ in ways related to their outcomes, and the record does not report an adjusted comparative analysis. The reported death counts likewise cannot establish treatment attribution from the information posted.

The record does not report the numerical result for the primary endpoint or analyses for the listed secondary outcomes. Consequently, it does not provide a basis for judging the size or precision of an efficacy effect, or for concluding that one regimen is more effective than the other. Nor does absence of a posted numerical result establish that an outcome did not occur. It means the result is not reported in the registry record.

As a general statistical principle, an estimate is more informative when readers can see its denominator, uncertainty, analysis population, and method. The registry includes some group denominators for serious adverse events, but it does not provide confidence intervals, p-values, or adjusted estimates. It also does not give the denominator basis for the listed serious-event term percentages. The appropriate interpretation is therefore limited to the recorded study design, endpoint definitions, and descriptive safety counts, with no causal or confirmatory efficacy claim.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the distinction between describing groups and comparing treatments. It evaluated two combination regimens in parallel, but allocation was nonrandomized. The group-specific counts can be useful descriptions of the posted safety record; they do not create the exchangeability that randomization is intended to support. Any comparison between these groups must account for that design limitation, and the registry does not report an adjusted comparison.

The primary endpoint is also specific to early-phase safety evaluation: a participant count meeting dose-limiting toxicity criteria during Cycle 1. Its definition shows why endpoints need explicit grading rules, thresholds, and observation windows. Yet an endpoint definition alone is not a result. The numerical primary endpoint estimate and its precision are not reported in the registry record.

The record also highlights the importance of complete analysis reporting. Several clinically meaningful secondary outcomes are listed, including response and survival measures, but no analyses are reported. Without estimates, uncertainty measures, analysis populations, and missing-data methods, readers cannot assess the magnitude or reliability of those outcomes. The serious-event term percentages also lack a stated denominator in the registry record.

These features matter for clinical researchers because transparency about design and analysis determines what a result can support. A descriptive safety summary can inform understanding of the observed record, while causal comparison and efficacy claims require additional evidence and analysis. This registry entry communicates the treatment structure and some safety counts, but leaves the main endpoint results and inferential details unreported.

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 most important trial-specific limitation in the registry record is nonrandomized allocation. The arms are not a like-for-like control comparison, and baseline characteristics or allocation procedures that could clarify group differences are not reported. The study is also open-label, with no masking. These design features limit causal interpretation, although the record does not establish that a specific bias occurred.

The registry status is terminated, but the reason for termination is not reported in the registry record. The record gives enrollment of 56 and the study dates, but does not report how many participants entered each analysis population or completed follow-up for each outcome. The DLT set is defined, but its size and primary event count are not reported.

Although the primary endpoint and its toxicity criteria are described, the numerical result is not reported. Secondary outcomes are listed, but the record reports zero analyses. Follow-up details, endpoint-specific denominators, missing-data handling, analysis methods, and uncertainty estimates are not reported in the registry record. The basis for the serious adverse-event term percentages is also not specified. These gaps prevent assessment of precision and limit interpretation of the safety summaries.

The registry does not report a statistical analysis plan, sample-size justification, interim-analysis approach, multiplicity strategy, or adjusted comparisons. The sample-size material is described as a planning illustration based on an observed effect and specified assumptions, not as the trial’s design; numerical planning results and the underlying observed effect are not reported in the registry record. These limitations mean the posted summaries should be treated as descriptive and incomplete rather than as a full comparative analysis.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of Melphalan Flufenamide (Melflufen) + Dex With Bortezomib or Daratumumab in Patients With RRMM — NCT03481556.
• Registry record last updated 2022-12-19; status last verified 2022-12.
• Results first posted 2022-12-19.
• 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

This record describes NCT03481556, an open-label, nonrandomized Phase 1/2a parallel study sponsored by Oncopeptides AB. It enrolled 56 patients with relapsed or relapsed-refractory multiple myeloma to melflufen and dexamethasone with either bortezomib or daratumumab. The recorded start date was 2018-04-12, primary completion date was 2022-02-02, and status is terminated.

The Phase 1 primary endpoint was the number of participants with a dose-limiting toxicity during Cycle 1, Day 1 to Day 28. The record defines the analysis population and toxicity criteria but does not report the endpoint result. It lists secondary response and time-to-event outcomes and reports zero analyses. Serious adverse-event counts and selected term percentages are posted, but their interpretation is limited by nonrandomized allocation and missing analysis detail. The reason for termination, statistical analysis plan, and numerical efficacy results are not reported in the registry record.