A Study to Learn About the Study Medicine (Elranatamab) in Participants With Multiple Myeloma That Has Come Back After Responding to Treatment or Has Not Responded to Treatment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Learn About the Study Medicine (Elranatamab) in Participants With Multiple Myeloma That Has Come Back After Responding to Treatment or Has Not Responded to Treatment (NCT05014412), a non-randomized phase 2 study. The primary outcome is Number of Participants With Grade 2 or Higher Cytokine Release Syndrome (CRS) During Cycle 1: Parts 1 and 2.

2. Clinical Question

3. Trial Design

The registry identifies this as a Phase 2 study; its official title describes a Phase 1/2 study. It was open-label, non-randomized, multicenter, and used a parallel model. The study is recorded as completed. Its start date was 2021-10-07 and its primary completion date was 2023-06-15. Enrollment is listed as 86.

Participants received elranatamab as a subcutaneous injection at a study clinic. The study had distinct parts: Part 1 evaluated step-up priming dosing; Part 2A addressed dose determination; Part 2B was dose expansion; and Part 2C explored higher dose intensity. The registry summary describes initial step-up doses followed by weekly dosing, with clinic visit frequency potentially decreasing over time. It also says participation would last at least two years. These are descriptions of the planned treatment and follow-up, not evidence that every participant followed an identical schedule.

Because treatment assignment was not randomized and there was no masking, the cohorts should be read as groups within a dosing study, not as treatment and control arms in a randomized trial. Differences in their participant counts or adverse-event summaries may reflect differences in cohort composition, dosing, follow-up, or other factors; the registry record does not establish the cause of any such difference.

The primary outcome combined Parts 1 and 2, consistent with the registry statement that the groups used the same priming regimen. The posted serious adverse-event summaries, in contrast, are separated by study part or dose cohort. The record does not report a sample-size justification, detailed statistical analysis plan, or interim-analysis plan.

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: Results are reported only for primary outcome measure and those secondary outcome measures whose analysis was final at primary completion date (15-June-2023). Remaining secondary outcome measures results would be reported once analysis is final.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety analysis set included all enrolled participants who received at least 1 dose of study intervention. Data for this outcome is presented for all participants in Part 1 and 2 of the study (combined) per study design, as all treatment groups utilized the same elranatamab priming regimen (4 mg on Day 1/20 mg on Day 4, followed by 76mg QW) during Cycle 1.

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: All enrolled participants who received at least 1 dose of study intervention.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Grade 2 or Higher Cytokine Release Syndrome (CRS) During Cycle 1: Parts 1 and 2, measured over Parts 1 and 2: Cycle 1 (28 days).

The primary endpoint counts participants with Grade 2 or higher cytokine release syndrome (CRS) during Cycle 1, which the registry defines as 28 days. CRS is an inflammatory response associated with activation or engagement of immune effector cells. The registry description requires fever at onset and notes that symptoms may include low blood pressure, low oxygen, or organ dysfunction. It outlines severity grades using the American Society for Transplantation and Cellular Therapy criteria, with organ toxicities graded according to CTCAE v5.0.

Counting participants who reach at least Grade 2 focuses the outcome on events classified as moderate or more severe, rather than counting only any CRS occurrence. In general, a thresholded safety endpoint can give a clear count for a clinically defined level of severity, while not conveying the full range of event severity, duration, or clinical course. Those details require other results or individual-level information.

The registry specifies that the endpoint covers Parts 1 and 2 combined and defines the safety analysis set as enrolled participants who received at least one dose of study intervention. It does not report the observed count for this primary endpoint, nor a confidence interval or other uncertainty estimate. The endpoint definition alone therefore does not reveal how often Grade 2 or higher CRS occurred in this study.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help distinguish what these results can describe from what they cannot establish. The explanations in this discussion are general; trial-specific statements are identified as descriptions of this registry record.

What does a participant count describe?

A count reports how many participants met an outcome definition in a defined group and period. For the primary endpoint, the definition is Grade 2 or higher CRS during Cycle 1, a 28-day period. A count is directly interpretable only alongside its population, timeframe, and event definition. The registry names those features but does not report the primary count. Therefore, the event frequency for that endpoint cannot be calculated from the record.

For safety summaries, a count among participants at risk describes the observed burden in that cohort. It does not by itself describe the rate over time, because participants may differ in how long they were followed or exposed. Nor does a count show whether events were mild or severe unless the outcome definition specifies severity. The registry gives serious-event counts and separately lists selected event terms; those are different summaries and should not be conflated.

What would a confidence interval add?

In general, a confidence interval expresses the statistical uncertainty around an estimate under a specified method and assumptions. It helps readers distinguish an estimate that is relatively precise from one that remains compatible with a wider range of values. It does not account automatically for every possible source of bias, such as selection into non-randomized cohorts or differences in follow-up.

The registry record does not report a confidence interval for the primary endpoint or for the serious adverse-event counts. Without an estimate and its uncertainty, it is not possible to assess the precision of the primary endpoint result. The counts alone should not be treated as precise estimates of the underlying event frequency.

Why does non-randomization matter?

Random allocation is one way to make comparison groups similar, on average, in both measured and unmeasured characteristics. This study was non-randomized. Its parts and dose cohorts were created for dosing evaluation, not as randomized control groups. Participants may differ between cohorts in ways that affect outcomes, and the registry record does not report an adjustment strategy that would address such differences. Any apparent numerical contrast between cohorts is therefore descriptive and cannot be attributed to dose on the basis of these summaries.

Open-label treatment means masking was absent. For objective safety events, lack of masking does not necessarily change whether an event occurred, but it can matter to assessment, reporting, or decisions about care. The record does not describe procedures used to reduce potential assessment bias, so the extent of any such influence is not reported in the registry record.

What can planning calculations tell readers?

In general, sample-size calculations estimate how many participants a future study might need under stated assumptions about the effect to detect, statistical significance, allocation, and analysis. They are planning illustrations, not evidence that a study had a particular probability of detecting an effect after its results are known. The registry record’s sample-size assumptions characterize its planning illustrations as based on an observed effect, with equal allocation, a two-sided significance level of 0.05, and a normal approximation. Such illustrations are not observed power and do not substitute for a confidence interval or a prespecified analysis of the primary endpoint.

The record does not state the trial’s own sample-size justification. It also does not report an estimate for the primary outcome from which readers could assess the statistical uncertainty of that outcome. Any planning illustration should therefore be kept separate from the study’s observed safety findings.

How should adverse-event terms be interpreted?

Safety summaries may count participants with at least one event, individual event occurrences, or events grouped by preferred term. These measures are not interchangeable. A participant can have more than one event, and one participant may contribute to more than one term. Unless a registry description clearly specifies the denominator and counting rules for a percentage, readers should not assume that it is the proportion of the entire cohort with that event. In this record, the selected serious-event terms are listed with percentages, but the denominators and detailed counting rules are not reported in the registry record.

Over-dispersion is a general statistical issue that arises when observed variability is greater than a simple model assumes. In count analyses, for example, repeated events or substantial differences between participants can make a basic model underestimate uncertainty. This study’s primary endpoint is a count of participants meeting a binary event definition, not a reported recurrent-event total. The registry does not report a model, dispersion assessment, or analysis details for the primary endpoint, so no model-based interpretation can be evaluated.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 18 outcome measures, including safety outcomes and an objective response rate outcome. When a study examines multiple outcomes, there is a general risk that highlighting selected findings can overstate how much evidence a collection of results provides. Statistical approaches to multiplicity may adjust significance thresholds or otherwise define how results should be interpreted together. The registry record does not report a multiplicity strategy, so it is not possible to determine whether or how the outcomes were treated as a family of tests.

The record does not report the number of participants with the primary endpoint, an effect estimate, or a confidence interval for it. It also does not report a missing-data method for this endpoint. The approach to participants who discontinued, had incomplete event assessment, or lacked endpoint data is therefore not reported in the registry record. The defined safety analysis set includes enrolled participants who received at least one dose, but the registry does not provide the set’s endpoint-specific denominator or explain how missing observations were handled.

For the secondary outcomes, the registry names dose-limiting toxicities, adverse events, serious adverse events, maximum adverse-event grades, CRS and ICANS, laboratory shifts, liver-function abnormalities, and objective response rate. The available record does not describe a full analysis plan for these outcomes. It does not report whether analyses were adjusted for multiplicity, how missing data were handled, or whether the analysis populations differed across outcomes.

These omissions matter because selective availability of outcomes or different analysis populations can affect interpretation. They do not prove that analyses were inappropriate; they mean the relevant methods are not reported in the registry record. The posted counts should be read as descriptive information, not as a complete inferential analysis of every outcome.

11. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cytokine release syndrome (50.0%), pneumonia (27.3%), covid-19 pneumonia (25.0%), disease progression (18.2%), lower respiratory tract infection (16.7%).

The registry reports serious adverse-event affected-participant counts by cohort: Part 1, 23 among 33 at risk; Part 2A Dose Level 1, 11 among 12; Part 2A Dose Level 2, 8 among 11; and Part 2B, 21 among 29. These values describe the recorded cohorts, not randomized comparisons. Because the study was non-randomized, differences across cohorts cannot be attributed to dose without additional design and analysis support.

The listed serious-event terms include cytokine release syndrome at 50.0%, pneumonia at 27.3%, COVID-19 pneumonia at 25.0%, disease progression at 18.2%, lower respiratory tract infection at 16.7%, and SARS-CoV-2 test positive at 16.7%. The registry does not report the denominator or detailed counting rules for these percentages. They should not be read as percentages of all participants in the study, nor should the terms be assumed to be mutually exclusive.

Seriousness is not the same as treatment relatedness. The record includes adverse-event outcomes described as covering all causalities and treatment-related events, but the listed counts do not establish that an event was caused by elranatamab. Death counts are also listed by cohort, but cause, timing, and treatment relationship are not reported in the registry record.

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

The registry record establishes that a completed, open-label, non-randomized study evaluated elranatamab dosing approaches in participants with relapsed or refractory multiple myeloma. It describes a primary safety endpoint based on Grade 2 or higher CRS during Cycle 1 and includes serious adverse-event counts by cohort. These details characterize the study’s question and some of its safety reporting.

The primary endpoint’s observed participant count is not reported in the registry record. As a result, the record does not support a numerical conclusion about how often this endpoint occurred, or how precisely its frequency was estimated. A stated endpoint definition is not itself an outcome result.

The serious adverse-event counts and listed terms provide descriptive information, but they do not establish a causal relationship with treatment. The cohorts were not randomized, and there is no like-for-like control group. Counts across parts or dose levels should not be taken as proof that one regimen caused a higher or lower event burden than another. The record also does not report enough information about the denominators for the listed serious-event percentages to interpret them as cohort incidence estimates.

These data do not establish comparative efficacy. Although the registry lists objective response rate among secondary outcomes, its observed result is not included in the record. Nor do the safety summaries establish that treatment is effective or ineffective. They are limited to the recorded study structure and the outcomes reported.

In general, a fuller interpretation would require endpoint-specific results, denominators, uncertainty estimates, analysis populations, and methods for handling missing data and multiple outcomes. Those details are not reported in the registry record. The appropriate reading is therefore descriptive and bounded: the registry identifies what the study set out to assess and provides some cohort-level safety summaries, but it does not provide the primary outcome result or a basis for causal treatment comparisons.

13. Why This Trial Matters Statistically

This trial raises statistical questions that commonly arise in early dosing studies. Its parts address step-up priming, dose determination, dose expansion, and exploration of higher dose intensity. Such a structure can organize safety and dosing evaluation across cohorts, but non-randomized cohorts do not have the same interpretive role as randomized comparison groups. Their counts describe what was observed in each cohort; they do not isolate a dose effect.

The choice of a participant-based CRS endpoint illustrates why outcome definitions matter. A severity threshold and a defined observation period make the event count interpretable in principle. However, readers also need the observed count, denominator, and uncertainty estimate. The registry record states the endpoint definition and Cycle 1 timeframe but does not report the primary count, leaving the central safety question unquantified in the record.

Safety summaries also demonstrate the importance of denominators and attribution. Serious adverse events, selected event terms, and deaths answer different descriptive questions. A percentage attached to an event term cannot be interpreted confidently without knowing its denominator and counting rules. Likewise, recording an event during a study does not by itself show that the intervention caused it.

The record lists multiple outcome measures but does not report a multiplicity approach, missing-data method, or full analysis plan. These omissions limit assessment of how results across outcomes were selected and how uncertainty was handled. The study is therefore statistically informative as an example of why study design, endpoint reporting, and analysis transparency must be read together: the cohort descriptions and event summaries provide context, while the unavailable primary result and analysis details constrain inference.

14. 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 direct limitation in the registry record is that the primary endpoint is defined but its observed count is not reported. No estimate of uncertainty for that endpoint is reported either. This prevents assessment of its observed frequency or precision.

The study was non-randomized and open-label, with cohorts organized by study part or dose level. These groups are not equivalent to randomized treatment and control groups. Confounding and differences in cohort composition or follow-up may affect descriptive contrasts, and the registry does not report an adjustment method that would address these concerns.

Although the safety analysis set is described as enrolled participants who received at least one dose, the endpoint-specific denominators and missing-data handling are not reported. The record also does not describe how long participants in each cohort were observed for the serious adverse-event summaries. The listed serious-event percentages do not have reported denominators or detailed counting rules.

The record names a broad set of outcomes but does not report a multiplicity plan or a full statistical analysis plan. It also does not report the study’s sample-size justification. Death counts are listed, but cause, timing, and relation to treatment are not reported in the registry record. The primary endpoint description includes an incomplete parenthetical about the priming regimen, so the specific regimen details in that passage cannot be fully characterized from the record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study to Learn About the Study Medicine (Elranatamab) in Participants With Multiple Myeloma That Has Come Back After Responding to Treatment or Has Not Responded to Treatment — NCT05014412.
• Registry record last updated 2026-02-10; status last verified 2026-01.
• Results first posted 2024-07-30.
• 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.

18. Record Summary

The registry records a completed, open-label, non-randomized, multicenter study of elranatamab in participants with relapsed or refractory multiple myeloma. It lists Phase 2, while the official title describes a Phase 1/2 study. Enrollment is 86. The study evaluated step-up priming and different dosing approaches across Parts 1, 2A, 2B, and 2C.

The primary endpoint was the number of participants with Grade 2 or higher CRS during Cycle 1, defined as 28 days, across Parts 1 and 2. Its observed result is not reported in the registry record. Serious adverse-event counts and selected terms are listed by cohort, but the groups are not randomized comparators, and the record does not provide the details needed for causal interpretation. Missing-data handling, multiplicity methods, the full statistical analysis plan, and the primary endpoint’s uncertainty estimate are not reported in the registry record.