A Study of Elranatamab (PF-06863135) in Chinese Participants With Refractory Multiple Myeloma.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Elranatamab (PF-06863135) in Chinese Participants With Refractory Multiple Myeloma. (NCT05228470), a na phase 2 study. The primary outcome is Objective Response Rate (ORR) by Blinded Independent Central Review (BICR) as Per International Myeloma Working Group (IMWG) Criteria.

2. Clinical Question

The study was intended to assess safety, pharmacokinetics, pharmacodynamics and efficacy in Chinese participants with refractory multiple myeloma. The record describes the Phase 1b portion as helping to assess a safe dose and the Phase 2 portion as monitoring myeloma growth during treatment. Those aims describe the study questions; they do not establish what the unreported primary efficacy estimate was.

3. Trial Design

This was a Phase 1b/2, open-label, single-group study of elranatamab in Chinese participants with multiple myeloma refractory to at least one proteasome inhibitor, one immunomodulatory drug and one anti-CD38 antibody. The registry lists the study as Phase 2, describes both Phase 1b and Phase 2 parts, and records enrollment of 39. The study started on 2021-12-21, had primary completion on 2023-08-06, and is listed as completed.

In Phase 1b, participants received elranatamab by subcutaneous injection using priming and full doses. The brief summary says that safety and reactions to the study medicine were monitored to help understand dosage. In Phase 2, participants received elranatamab alone, with myeloma growth monitored. Participants in that part were expected to take part for about 2 years. The registry does not report further detail about the dose schedule in the information available for this analysis.

There was no randomized control arm: allocation is listed as not applicable, masking as none, and the model as single group. Open-label treatment means the study was not masked. The primary endpoint nevertheless specifies blinded independent central review for response assessment. The registry record does not describe the central review procedures in further detail, so the operational safeguards used in that review are not reported in the registry record.

The primary ORR analysis was planned for participants who started with the recommended Phase 2 dose, including participants from both study parts. The safety analysis set was defined as all enrolled participants who received at least one dose. The count in the primary analysis population is not reported in the registry record. The listed enrollment and the safety groups should not be treated as interchangeable without that analysis-population detail.

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 39 participants were enrolled, and 38 participants were assigned to study treatment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: DLT evaluable analysis set included all participants enrolled to Phase 1b part and who had a DLT in the DLT observation period or completed the DLT observation period without DLT. Participants without DLTs and without the minimum required exposure for reasons other than treatment-related toxicity were not evaluable for DLTs and were replaced.

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: Safety analysis set included all participants enrolled to study who took at least 1 dose of study intervention.

6. Primary Endpoint

The registry lists the primary outcome as Objective Response Rate (ORR) by Blinded Independent Central Review (BICR) as Per International Myeloma Working Group (IMWG) Criteria, measured over From date of first dose until confirmed disease progression (PD), death, start of new anticancer therapy, whichever occurred first (approximately up to 16 months).

The primary endpoint is objective response rate (ORR), expressed as the percentage of participants whose best overall response was a confirmed stringent complete response, complete response, very good partial response or partial response. Response was assessed using International Myeloma Working Group criteria by blinded independent central review. The registry describes assessment from the date of first dose until confirmed disease progression, death, the start of new anticancer therapy, or whichever occurred first, approximately up to 16 months.

These response categories reflect differing degrees of change in measurable myeloma findings. The registry criteria include measures based on serum and urine M-protein, serum free light chains, bone marrow findings and soft tissue plasmacytomas. For example, complete response criteria include negative serum and urine immunofixation, disappearance of any soft tissue plasmacytoma and less than 5% plasma cells in bone marrow aspirate. Partial response and very good partial response use specified reductions in disease markers. The full response definitions also vary according to whether serum and urine M-protein can be measured.

In general, ORR is used to summarize the proportion of participants meeting a prespecified response definition, rather than the duration of response or time until disease progression. A confidence interval communicates uncertainty around an estimated response percentage; it does not by itself establish how results would compare with another treatment. The registry specifies a 95% confidence interval, but the numerical ORR and interval are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a percentage endpoint, an assessment framework and a planned analysis population. Those details make clear what the primary outcome was intended to summarize, but they do not provide the numerical result. The following explains the statistical concepts relevant to interpreting the recorded methods.

What does the response percentage represent?

In general, a response percentage is the number of participants meeting the response definition relative to the analysis population used for that endpoint. ORR groups together participants whose best overall response reaches one of the qualifying categories. Here those categories are stringent complete response, complete response, very good partial response and partial response under International Myeloma Working Group criteria. The exact response numerator, denominator and estimate are not reported in the registry record, so none can be stated.

The response categories rely on disease measurements rather than a single finding. The registry criteria refer to serum and urine M-protein, serum free light chains, bone marrow results and soft tissue plasmacytomas, with specific criteria for stringent complete response, complete response, very good partial response and partial response. In general, defining categories in advance helps make the endpoint more reproducible, but interpretation still depends on how measurements were collected, whether assessments were available and how response confirmation was implemented. Those operational details are not reported in the registry record.

Why use blinded independent central review?

The endpoint names blinded independent central review (BICR) as the assessor of ORR. In general, independent central review is intended to apply response criteria consistently using centrally reviewed data. Blinding can reduce the influence of knowledge about treatment or other information on assessment. That feature is relevant even in an open-label trial, because treatment assignment and outcome assessment are separate aspects of study conduct. The registry record does not describe the review charter, reviewer blinding procedures or how disagreements were resolved.

Investigator assessment is listed for several secondary outcomes, including ORR. In general, investigator and central assessments can differ because assessment processes and judgments may not be identical. The registry names both types of assessment but does not report their numerical results or the degree of agreement between them.

What does a 95% confidence interval communicate?

The primary endpoint specifies a 95% confidence interval. In general, a confidence interval gives a range of values compatible with the observed data under the statistical method and its assumptions. It describes uncertainty in an estimate, not the range of individual participant outcomes and not a probability that a particular treatment effect is true. Its width is relevant to precision: limited information generally yields less precise estimates. The interval for this endpoint is not reported in the registry record, so its precision cannot be assessed.

A confidence interval does not create a comparison where none exists. This study has a single-group design and no concurrent control group. An interval around the response proportion would describe uncertainty in that proportion, not the difference between elranatamab and a comparator. General statistical reasoning therefore separates estimation of an observed response proportion from estimation of a comparative treatment effect.

Why does the analysis population matter?

The primary analysis was planned for participants who started with the recommended Phase 2 dose, including participants from both Phase 1b and Phase 2. The safety analysis set included all enrolled participants who received at least one dose. These are distinct definitions for distinct purposes. In general, the denominator for an endpoint affects the estimate, so a reader needs to know which participants were included and how participants without an evaluable response were handled. The primary analysis population size and handling of unevaluable or missing response data are not reported in the registry record.

The enrollment entry is 39, while the recorded safety groups list a combined group at risk of 38. Those entries do not by themselves establish why the figures differ or which participants contributed to the primary analysis. The registry record does not explain that relationship. They should not be reconciled by assuming an unreported exclusion or treating either number as the primary endpoint denominator.

What do the other outcomes add?

The registry lists duration of response, complete response rate, investigator-assessed ORR, duration of complete response and progression-free survival among the secondary outcomes. In general, these outcomes address different features: response duration concerns how long a response persists, while progression-free survival concerns time until progression or death under the specified endpoint definition. The numerical results and detailed analysis methods for these outcomes are not reported in the registry record, so their estimates cannot be interpreted.

The record also lists 28 outcome measures and one analysis. Those record entries do not provide a full statistical analysis plan. The planned methods for confidence interval construction, censoring, model choices, covariate adjustment and sensitivity analyses are not reported in the registry record. No inferential comparison should be inferred from the count of listed outcomes or analyses.

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("Phase 1b", "Phase 2", "Phase 1b + Phase 2")
n      <- c(8, 30, 38)
events <- c(3, 16, 19)
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  Phase 1b  8  3  37.5  8.5  75.5  13.7  69.4  13.7  70.1
ARM  Phase 2  30  16  53.3  34.3  71.7  36.1  69.8  36.0  69.8
ARM  Phase 1b + Phase 2  38  19  50.0  33.4  66.6  34.8  65.2  34.8  65.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary ORR endpoint and multiple secondary outcomes, including response duration, complete response rate, investigator-assessed ORR, duration of complete response and progression-free survival. It records 28 outcome measures and one analysis. However, a full plan for handling multiple endpoints or multiple statistical tests is not reported in the registry record. The record does not describe a testing hierarchy, adjustment for multiplicity, or whether the secondary outcomes were intended to support formal confirmatory claims. Without those details and numerical results, the listed outcomes should be treated as distinct measures rather than as a set of statistically controlled findings.

The registry defines the primary analysis population as participants who started with the recommended Phase 2 dose, including participants from Phase 1b and Phase 2. It separately defines the safety analysis set as all enrolled participants who received at least one dose. The primary analysis population size is not reported in the registry record. The record does not report how participants with missing, unevaluable or unconfirmed response assessments were handled, nor does it describe imputation or sensitivity analyses for missing outcome data.

In general, missing outcome data can affect both the estimated response proportion and its precision, especially if the reason data are missing is related to participants' outcomes. This is a general concern, not a claim that missing data occurred in this study. The extent and handling of missing primary endpoint data are not reported in the registry record.

The registry record also does not report a sample-size justification, interim analysis plan or complete statistical analysis plan. Those details cannot be inferred from the enrollment entry or from the completed status. The posted endpoint definition and analysis-population description are useful, but they do not resolve these methodological uncertainties.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pneumonia (40.0%), anaemia (12.5%), coagulopathy (12.5%), neutropenia (12.5%), thrombocytopenia (12.5%).

The registry lists serious adverse event counts for Phase 2, Phase 1b and the combined Phase 1b plus Phase 2 group. The recorded numbers are 22 of 30 in Phase 2, 6 of 8 in Phase 1b and 28 of 38 in the combined group. These are counts of participants affected among the stated group sizes; they are not a comparison against a control group. The record also lists other adverse events as 30 of 30, 8 of 8 and 38 of 38 for those groups, respectively.

The listed serious adverse event terms include pneumonia at 40.0%, and anaemia, coagulopathy, neutropenia, thrombocytopenia and gastrointestinal haemorrhage at 12.5% each. The denominator and calculation details for these term percentages are not reported in the registry record. The terms should therefore be read as the listed percentages, not as a basis for reconstructing participant counts or comparing risks across groups.

Deaths are recorded as 17 for Phase 2, 6 for Phase 1b and 23 for the combined group. The registry entry does not establish that these deaths were caused by elranatamab or by a particular adverse event. Serious adverse event counts, other adverse event counts and deaths are different safety summaries and should not be treated as interchangeable measures. The combined safety group includes 38 participants, while enrollment is listed as 39; the registry record does not explain that difference.

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

The registry establishes the study question and design: elranatamab was evaluated in Chinese participants with triple-class refractory multiple myeloma in an open-label, single-group Phase 1b/2 study. The primary endpoint was the percentage with a confirmed response under International Myeloma Working Group criteria, assessed by blinded independent central review. The registry also records safety outcomes by study group.

What the record does not establish is the magnitude or precision of the primary response result. The numerical ORR estimate and its 95% confidence interval are not reported in the registry record. Secondary efficacy outcomes and their numerical results are also not reported. Consequently, the endpoint definition should not be mistaken for an observed response result, and no quantitative statement about response can be made from the record.

In general, an observed response proportion in a single-group study is descriptive of the participants in the analyzed population. Without random allocation and a concurrent comparator, it does not provide a direct estimate of how outcomes would differ under another treatment or no treatment. This design limitation remains even if a response estimate is available. It also means that results cannot be attributed to treatment by comparison within this study alone.

The safety counts indicate what was recorded in the registry groups, but they do not by themselves establish causality, comparative safety or the context and timing of each event. The listed deaths should not be assumed to be treatment-related. Detailed safety definitions, follow-up information for each event and causal assessments are not reported in the registry record.

The interpretation is therefore bounded by the documented information: the study's population, intervention, single-group design, endpoint definition, planned analysis population and listed safety counts. The record does not provide enough numerical efficacy information to quantify the primary response finding, and it does not support a randomized treatment comparison.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how an efficacy question can be framed without a randomized comparator. The primary endpoint is defined as ORR under named response criteria and central review. That makes the intended outcome and assessment approach identifiable, while the single-group design means any estimate would describe observed responses rather than a randomized contrast. The design and the endpoint answer different questions: one concerns what is measured, and the other concerns what comparisons the study can support.

The record also distinguishes the planned primary efficacy population from the safety analysis set. This matters because a percentage outcome depends on the participants included in its denominator. The primary analysis was planned for participants who started at the recommended Phase 2 dose across both study parts, while the safety set included enrolled participants who received at least one dose. The actual primary analysis population size is not reported in the registry record, so the enrollment entry cannot stand in for that denominator.

It is also important that the registry specifies BICR for the primary outcome while describing the trial as open-label. In general, independent central assessment can help standardize outcome classification, but it does not make the treatment comparison randomized or remove all uncertainty about implementation. The record does not give procedural details or the numerical response result, limiting assessment of both the endpoint estimate and its precision.

Finally, the record lists safety outcomes alongside efficacy outcomes, but the available counts do not establish comparative risk or causation. The absence of the primary numerical efficacy result is itself a key interpretive limit: a defined endpoint is not equivalent to a reported finding. Readers can identify the intended analysis and safety summaries, but cannot evaluate the magnitude of the primary response estimate from the registry record.

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 direct limitation for interpreting efficacy is that the numerical primary ORR result and its 95% confidence interval are not reported in the registry record. Numerical results for the listed secondary efficacy outcomes are also not reported. The record therefore does not allow readers to assess the response estimate, its precision, or the secondary outcome findings.

The study was open-label and single-group, with no concurrent comparator. It cannot provide a randomized comparison of elranatamab with another treatment or with no treatment. The registry record does not report details that would support adjustment for differences from external populations or studies, and comparisons with other studies would not replace a within-study control group.

The primary analysis population was defined as participants who started at the recommended Phase 2 dose, including participants from Phase 1b and Phase 2, but its size is not reported. Enrollment is listed as 39, whereas the combined safety group lists 38 at risk. The registry record does not explain this difference. It also does not report the handling of missing or unevaluable response assessments, the method used to construct the confidence interval, or sensitivity analyses.

The registry names blinded independent central review but does not report operational details such as review procedures or disagreement resolution. It lists multiple secondary outcomes, but multiplicity control and the full statistical analysis plan are not reported. A sample-size justification, interim analyses and further statistical planning details are likewise not reported in the registry record.

Safety interpretation is limited by the absence of contextual details for the listed event counts and percentages. The term-percentage denominator is not reported, and the death counts do not establish causation. These limitations are specific to the information recorded and should not be replaced with assumptions about conduct or results.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Elranatamab (PF-06863135) in Chinese Participants With Refractory Multiple Myeloma. — NCT05228470.
• Registry record last updated 2026-09-29; status last verified 2026-09.
• Results first posted 2024-09-19.
• 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

The registry identifies a completed, open-label, single-group Phase 1b/2 study of elranatamab in Chinese participants with multiple myeloma refractory to at least one proteasome inhibitor, one immunomodulatory drug and one anti-CD38 antibody. Enrollment was 39. The study started on 2021-12-21 and had primary completion on 2023-08-06.

The primary endpoint was ORR under International Myeloma Working Group criteria, assessed by blinded independent central review. The planned primary analysis included participants who started at the recommended Phase 2 dose across the two study parts. The numerical primary result, its 95% confidence interval and the primary analysis population size are not reported in the registry record.

The registry lists safety counts by Phase 2, Phase 1b and combined groups, along with serious adverse event terms and death counts. These data are descriptive and do not provide a randomized comparison or establish causality. Further details about missing data, multiplicity and the complete statistical plan are not reported in the registry record.