Plerixafor and Cemiplimab in Metastatic Pancreatic Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Plerixafor and Cemiplimab in Metastatic Pancreatic Cancer (NCT04177810), a na phase 2 study. The primary outcome is Objective Response Rate (ORR) Using Immune RECIST (iRECIST) Criteria.

2. Clinical Question

In practical terms, the endpoint asks whether participants experienced a qualifying reduction or disappearance of target lesions during the study. It does not, by itself, compare the combination with another treatment or with no treatment. The registry record states that the study was intended to evaluate safety and clinical activity of the combination in metastatic pancreatic cancer.

The record also names overall response rate under RECIST 1.1 criteria and the number of participants experiencing grade 3 or above drug-related toxicities as secondary outcomes. Those are distinct questions: the response outcome uses a different assessment framework, while the toxicity outcome concerns severity and drug relationship. Neither secondary outcome changes the single-group design or supplies a concurrent comparison.

The registry record does not report a numerical primary response result, a confidence interval, or an analysis population for the endpoint. As a result, the clinical question can be described from the endpoint definition, but the posted record does not establish how many participants met it or how precisely a response frequency was estimated.

3. Trial Design

This was a phase 2 study of plerixafor and cemiplimab in metastatic pancreatic cancer. The record lists the study as completed, with 25 participants enrolled. The recorded start date is 2020-11-16 and the primary completion date is 2023-03-29.

The design is classified as single group, with allocation listed as NA and masking listed as none. Participants in the sole group were described as receiving both cemiplimab and plerixafor. There is no randomized control arm or like-for-like comparator in the registry record. Consequently, outcomes from this study are observed in the context of the combination and cannot, through this design alone, isolate the contribution of either drug or compare the combination directly with another treatment.

The primary outcome is the objective response rate under iRECIST criteria, expressed in the record as a count of participants. Its stated timeframe is 10 months. The record also lists two secondary outcomes: overall response rate using RECIST 1.1 criteria and participants experiencing grade 3 or above drug-related toxicities. The registry record does not report further details about the assessment schedule, the treatment regimen, eligibility criteria, or the statistical analysis plan.

The record identifies Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins as the sponsor. It does not report a randomized allocation scheme, masking procedures, or a separate comparator intervention. This design can describe outcomes among people treated in the study group, but it cannot provide the protections against confounding that a randomized comparison can offer. In particular, changes over time or differences between participants cannot be attributed to the combination by comparing outcomes against an untreated or alternative-treatment group within this trial.

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: 4 participants were excluded from analysis because they did not receive at least one dose of study drug.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: 4 participants were excluded from analysis because they did not receive at least one dose of study drug.

6. Primary Endpoint

The registry lists the primary outcome as Objective Response Rate (ORR) Using Immune RECIST (iRECIST) Criteria, measured over 10 months.

The primary endpoint is the number of participants achieving an objective response under immune RECIST (iRECIST) criteria. The registry defines response as a complete response or partial response at any time during the study, within the stated 10-month timeframe. A complete response is described as disappearance of all target lesions. A partial response is described as a decrease of at least 30% in the sum of target-lesion diameters. The record defines progressive disease as an increase of more than 20% in that sum, and stable disease as neither the specified decrease nor increase.

Response endpoints are used to record whether tumors meet prespecified imaging-based criteria for shrinkage or disappearance. A count of responders is an accessible summary of that outcome, but its interpretation depends on the number of participants assessed and on how response is determined over time. The registry record reports neither a numerical response count nor the denominator used for a primary response analysis, so the response frequency and its precision are not available from the posted results.

The endpoint uses iRECIST, while the named secondary response outcome uses RECIST 1.1. These are separate assessment frameworks; their results should not be treated as interchangeable. The record does not report why iRECIST was selected, how assessments were reviewed, or how missing or unevaluable assessments were handled.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical details that can be interpreted are limited. The registry record gives a single-group design, a participant-count primary endpoint, a 10-month timeframe, and an iRECIST response definition. It does not report an analysis estimate or statistical plan. The explanations below describe general statistical concepts and distinguish them from information documented for this study.

What does a participant count convey?

In general, a count records how many people in an analysis group meet a defined outcome. To interpret that count as a response rate, it needs a denominator: the number of people assessed for the endpoint. Counts can be affected by whether participants were assessed, whether assessments were evaluable, and how missing information was treated. The primary endpoint is described as a count of participants, but the primary analysis denominator and response count are not reported in the registry record.

Why does the endpoint definition matter?

An endpoint definition sets the rules for classifying outcomes. Here, the record defines objective response as complete or partial response using iRECIST and provides lesion-change criteria for response, progression, and stable disease. Applying those rules consistently matters because a participant’s classification depends on the measurements and assessment process. The registry record does not report the imaging schedule, review process, or adjudication procedures, so those operational details are not available for evaluation.

The secondary response outcome is named using RECIST 1.1 rather than iRECIST. In general, endpoints based on different criteria can classify outcomes differently; therefore, the results for one framework should not automatically be substituted for the other. The registry record does not give numerical results for either response outcome.

How should uncertainty be understood?

In general, a confidence interval describes a range of values compatible with the data and the method used to calculate it. Its width reflects statistical precision: a wider interval indicates less precise estimation, while a narrower one indicates greater precision. For a response frequency, interpretation would ordinarily require both the estimate and its interval. Neither is reported for the primary endpoint in this registry record, so its precision cannot be assessed from the posted results.

A p-value, when reported, is a measure tied to a specified statistical test and null hypothesis; it is not a measure of the size or clinical importance of an effect. No primary analysis p-value or test is reported in the registry record. In a single-group study, any statistical test would also need a clearly stated reference value or comparison to answer a particular inferential question. The record does not report such a reference or test.

What does over-dispersion mean in general?

For count data, over-dispersion means that the observed variability is greater than a chosen model assumes. If a model does not account for that extra variability, its uncertainty estimates can be too small and its inferential results can appear more precise than warranted. This is a general statistical consideration; the registry record does not report a count model, an over-dispersion assessment, or a model-based analysis for this endpoint.

What can a single-group design estimate?

In general, a single-group study can report outcomes observed among people receiving the study intervention. A concurrent comparison group is needed to estimate a treatment contrast within the study, and randomization helps make comparison groups comparable in expectation. This study has no comparator group, so it does not directly estimate a difference between the combination and another treatment. Nor can it distinguish the separate contributions of the two drugs.

Because enrollment is not the same as an endpoint analysis population, the enrolled count does not determine the denominator for response analysis. The record does not report whether every enrolled participant began treatment, had evaluable assessments, or was included in the endpoint analysis. These details should not be inferred from the stated enrollment.

How should planning illustrations be read?

In general, a sample-size calculation illustrates how many participants may be needed under specified assumptions about an effect, variability, allocation, and significance level. It is a planning tool, not an observed outcome and not a measure of observed power. The planning assumptions described for this record use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, even though the registered study is single group. The illustrations are not the study’s own design justification. The registry record does not report the trial’s sample-size justification, and the posted information does not provide primary outcome results from which to evaluate an observed effect.

In general, calculations based on a fraction of an observed effect depend on the effect estimate used and the assumptions of the calculation. They do not demonstrate that a study had a particular probability of detecting its true effect. The planning illustrations should therefore be read as hypothetical planning scenarios rather than evidence about the study’s actual design or findings.

Which statistical details are unavailable?

The registry record does not report the primary analysis method, model, confidence interval method, hypothesis test, prespecified analysis population, missing-data approach, or handling of multiple outcomes. These omissions limit evaluation of how an estimate would have been derived and how robust it would be to alternative analytic choices. With no numerical primary estimate reported, readers cannot reproduce or independently assess an efficacy analysis from the registry record.

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("Cemiplimab and Plerixafor")
n      <- c(21)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Cemiplimab and Plerixafor  21  0  0.0  0.0  16.1  -0.0  15.5  0.1  15.4

11. Multiplicity, Missing Data and Analysis Populations

The record lists three outcome measures: the primary iRECIST response outcome and secondary outcomes for RECIST 1.1 response and grade 3 or above drug-related toxicities. Considering multiple outcomes can raise multiplicity concerns. In general, when several statistical tests are interpreted together, the chance of at least one apparently notable result may increase unless the analysis plan accounts for the number and role of the tests. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or adjusted results.

The analysis population for the primary endpoint is not reported in the registry record. The record states that 25 participants were enrolled, but does not say how many were treated, assessed, or included in each outcome analysis. It also does not report whether participants with missing assessments were excluded, counted as nonresponders, or handled by another method. These choices can affect a response count and its interpretation.

The registry record does not report the amount or pattern of missing outcome data, reasons for missingness, or sensitivity analyses. It also does not report an interim analysis plan, stopping rules, or a prespecified statistical analysis plan. No analysis results are reported in the registry record. Without those details, the stated outcome definitions can be identified, but the methods used to analyze them and account for missingness or multiple outcomes cannot be evaluated.

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: disease progression (38.1%), abdominal pain (14.3%), fever (14.3%), bile duct stenosis (4.8%), confusion (4.8%).

For the cemiplimab and plerixafor group, the registry safety entry reports 13 participants with serious adverse events among 21 at risk. It reports other adverse events in 21 participants among 21 at risk. These are separate categories in the record; the other-event count should not be added to the serious-event count, because a participant may appear in both categories.

The listed serious-event terms include Disease Progression at 38.1%, Abdominal pain at 14.3%, Fever at 14.3%, Bile Duct Stenosis at 4.8%, Confusion at 4.8%, and Delerium at 4.8%. These are registry-reported percentages. The record does not give event counts alongside each term in the information available, nor does it establish from the terms alone whether an event was caused by study treatment.

Seriousness is not equivalent to severity grading or drug relatedness. The secondary outcome concerns grade 3 or above drug-related toxicities, which is a specific classification. The serious-event listing should not be read as that secondary outcome or as proof that the combination caused the events. The record also does not explain the relationship between the safety denominator of 21 and the enrollment of 25, so that difference should not be attributed to a particular reason.

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

The study record establishes that a phase 2, single-group investigation of plerixafor with cemiplimab was completed in participants with metastatic pancreatic cancer. It specifies a primary response endpoint under iRECIST and lists secondary outcomes. Those details describe what the study set out to assess, but they do not report the primary response count or an estimate of response frequency.

Without the numerical endpoint result, its analysis denominator, and a measure of uncertainty, the registry record cannot show how often participants met the response definition or how precise that estimate was. The listed enrollment of 25 is not a substitute for an endpoint result, and it does not establish how many participants had evaluable response assessments.

Even a reported response estimate from this design would describe outcomes in the sole group receiving both drugs. With no randomized comparator, the study cannot provide a direct within-trial estimate of how outcomes differ from another treatment or from no study treatment. It also cannot determine the separate effect of either drug in the combination. These are design limits, not judgments about the therapies.

The safety information describes reported serious-event categories and terms, but does not establish that every event was treatment-related. The separately named toxicity outcome concerns grade 3 or above drug-related events; its numerical result is not reported in the registry record. Therefore, the adverse-event listing should be interpreted as descriptive safety reporting rather than as a causal assessment.

Overall, the registry record documents a completed study with defined outcomes, but its posted results do not support a quantitative conclusion about the primary response endpoint. The absence of a reported estimate should not be mistaken for a zero response result, just as the study design should not be mistaken for a controlled comparison.

14. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation begins with the design and endpoint, not just the study’s title or treatment combination. A single-group study can collect information about outcomes among participants receiving the intervention, but it does not contain a randomized comparison capable of estimating a treatment contrast. That distinction is essential when interpreting clinical activity.

The primary outcome is a count of participants meeting an imaging-based response definition. Such a count needs a clear denominator and assessment process to support interpretation. Although the registry record specifies iRECIST criteria and a 10-month timeframe, it does not report the primary count, the endpoint analysis population, or an uncertainty estimate. This makes the statistical evidence for the primary question unavailable in the posted record.

The registry also names a second response endpoint using RECIST 1.1 and a toxicity endpoint. Different endpoints answer different questions, and multiple outcomes create a need for transparent analysis planning. The record does not report how multiplicity, missing assessments, or analysis populations were handled.

The safety figures provide descriptive information, but they should not be treated as proof of causation or as interchangeable with the named drug-related toxicity endpoint. Separating event seriousness, severity grade, and attribution is a basic part of sound safety interpretation.

For biostatisticians and clinical researchers, this record is a useful reminder that design details, endpoint definitions, denominators, uncertainty, and analysis methods work together. A completed trial and clearly stated endpoint do not by themselves provide an interpretable efficacy estimate; the numerical result and its analytic context are also needed.

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 this trial is that the registry record does not report a numerical primary response result. It also does not report a confidence interval, endpoint analysis denominator, or primary analysis method. The stated enrollment of 25 therefore cannot be used as the number assessed for response.

The single-group design has no concurrent comparator and is not randomized. It can describe observed outcomes in the treatment group, but it cannot estimate a randomized treatment contrast or distinguish the contributions of plerixafor and cemiplimab. The record lists masking as none; it does not report additional details about outcome assessment or review.

The endpoint uses iRECIST, while a secondary response outcome uses RECIST 1.1. The registry record does not report the assessment schedule, imaging review process, adjudication method, or how differences between response criteria were handled. Missing-data amounts, reasons, and methods are not reported in the registry record either.

The primary analysis population, statistical model or test, multiplicity plan, interim analyses, and trial-specific sample-size justification are not reported in the registry record. Safety information has 21 participants at risk, but the record does not explain how that group relates to the 25 enrolled participants. The serious-event terms and percentages are descriptive and do not, by themselves, establish treatment causality or provide the result for the separate drug-related toxicity outcome.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Plerixafor and Cemiplimab in Metastatic Pancreatic Cancer — NCT04177810.
• Registry record last updated 2024-02-23; status last verified 2024-02.
• Results first posted 2024-02-20.
• 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 record describes a completed phase 2, single-group study of plerixafor and cemiplimab in metastatic pancreatic cancer. It lists 25 enrolled participants, with a start date of 2020-11-16 and a primary completion date of 2023-03-29. The primary outcome is the count of participants with an objective response under iRECIST criteria during 10 months.

The record also names RECIST 1.1 response and grade 3 or above drug-related toxicities as secondary outcomes. Safety reporting lists 13 of 21 participants at risk with serious adverse events and 21 of 21 with other adverse events. No numerical primary response result, analysis estimate, or confidence interval is reported in the registry record. With no randomized comparator, the design is descriptive rather than a controlled treatment comparison.