GVAX Pancreas Vaccine (With CY) in Combination With Nivolumab and SBRT for Patients With Borderline Resectable Pancreatic Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for GVAX Pancreas Vaccine (With CY) in Combination With Nivolumab and SBRT for Patients With Borderline Resectable Pancreatic Cancer (NCT03161379), a na phase 2 study. The primary outcome is CD8+ T Cell Density in Tumor Tissue.

2. Clinical Question

3. Trial Design

This was a phase II, single-group clinical trial evaluating a combined treatment approach in people with borderline resectable pancreatic adenocarcinoma. The registry lists the study as completed, with a start date of 2018-02-02 and a primary completion date of 2024-02-20. Its recorded enrollment is 31. Separately, the outcome description says that 18 participants were treated on study, and that 13 of them had sufficient tissue for the primary CD8 analysis. These counts refer to different stages or populations in the record and should not be treated as interchangeable.

The sole arm is described as CY, nivolumab, GVAX, and SBRT. The brief summary also mentions FOLFIRINOX, and the title describes definitive resection after the treatment approach. The interventions list identifies cyclophosphamide, nivolumab, GVAX Pancreas Vaccine, and SBRT. A detailed schedule, dose information, or sequencing beyond these descriptions is not reported in the registry record.

Allocation is listed as not applicable, and masking as none. This is therefore not a randomized comparison: there is no concurrent control arm in the record against which to estimate a relative treatment effect. Findings within this group can describe the observed participants and their outcomes, but cannot by themselves separate effects of individual components or establish what would have happened under another approach.

The registry identifies CD8+ T-cell density in tumor tissue as the primary outcome, measured at surgery. It also lists pathologic complete response rate at surgical resection as a secondary outcome. The record reports 2 outcome measures and 0 analyses. A protocol-level account of the statistical plan, sample-size justification, or interim analyses is 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: Participants with borderline resectable pancreatic cancer were enrolled on the study prior to starting standard of care chemotherapy. After completing chemotherapy, participants were re-screened to determine if they were eligible to continue on the study and receive study drug.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Only participants who received study drug, completed surgical resection, and had sufficient tissue to perform IHC analysis. Of the 18 participants treated on study, 13 had sufficient tissue to perform CD8 analysis.

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as CD8+ T Cell Density in Tumor Tissue, measured over evaluated at time of surgery, approximately 2 months from first dose of study drug.

The primary endpoint is the mean density of CD8+ T cells in resected tumor tissue. The registry describes the measurement as log(cells per mm^2), determined by immunohistochemistry. It was evaluated at the time of surgery, approximately 2 months from the first dose of study drug. The endpoint therefore summarizes a tissue measurement at a specified point in the treatment course; it is not itself a measure of survival, symptoms, or tumor control over time.

As general context, CD8+ T cells are immune cells that can be identified within tumor tissue. Measuring their density can describe the immune-cell presence in the sampled tissue. A mean provides a summary across the analyzed participants, while the standard deviation describes variation among their measurements. The logarithmic scale expresses density on a transformed scale; interpretation should therefore follow the stated scale rather than treating the measure as an untransformed cell count.

The analysis population is important to the endpoint’s meaning. Participants had to receive study drug, complete surgical resection, and have enough tissue for IHC. The record says 13 of the 18 treated participants had sufficient tissue for the CD8 analysis. It does not report the observed mean or standard deviation, so the size and variability of the endpoint cannot be assessed from the registry record. The endpoint’s numerical result is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

The registry identifies this as a single-group study, with allocation listed as not applicable and masking listed as none. A single-group design can describe outcomes among participants who receive the study approach. It does not supply a concurrent control group for estimating how outcomes would differ under another intervention. General statistical context: a treatment comparison is strongest when the groups are made comparable by design, such as through random allocation. Without such a comparison here, observed outcomes cannot be interpreted as an estimate of the regimen’s relative effect.

The combined nature of the approach adds another limitation. The study description includes CY, nivolumab, GVAX, and SBRT, while the brief summary also mentions FOLFIRINOX. A result for the overall study group would not isolate the effect of any one component. The registry record does not report a component-specific comparison.

What does the primary summary measure?

The primary endpoint is a continuous measure: mean CD8+ T-cell density in resected tumor tissue, expressed as log(cells per mm^2). A mean describes the center of the analyzed measurements. The listed dispersion measure is the standard deviation, which describes how spread out individual measurements are around the mean. These statistics would help readers distinguish a group average from variation among participants, but the registry record does not report the mean or standard deviation for this endpoint.

The logarithmic scale matters. As general context, transformations can be used when a measure spans a wide range or has a distribution for which analysis on the original scale is unsuitable. A mean on a log scale is not the same summary as a mean of untransformed cell densities. Interpretation should retain the stated scale, and a transformation alone does not indicate whether the study observed a large or small result. The registry record does not describe additional transformations, model choices, or assumptions used for the analysis.

Who contributed to the tissue endpoint?

The endpoint population includes participants who received study drug, completed surgical resection, and had sufficient tissue for IHC. The record says 18 participants were treated on study and 13 had sufficient tissue for CD8 analysis. Consequently, the primary endpoint is not described as an analysis of all 31 participants listed under enrollment. The registry does not provide the reasons for missing or insufficient tissue, nor does it report an analysis comparing participants with and without an evaluable specimen.

General statistical context: restricting an analysis to participants with an available measurement can be informative when the availability process is understood. If availability is related to participant characteristics or outcomes, the analyzed subset may not represent everyone enrolled or treated. This is a potential interpretive concern, not evidence that such a pattern occurred. The registry record does not report methods for handling missing tissue or other missing outcome data.

What does the analysis record show?

The record identifies 2 outcome measures and 0 analyses. It names CD8+ T-cell density as primary and pathologic complete response rate at surgical resection as secondary. The lack of a reported analysis means readers cannot assess a registry-posted estimate, confidence interval, or test for the primary endpoint from this information. The statistical model, handling of any repeated or clustered measurements, and inferential testing details are not reported in the registry record. No analysis method should be inferred from the endpoint description alone.

General statistical context: an estimate and its uncertainty answer different questions. An estimate summarizes the observed data, while a confidence interval describes a range of values compatible with the data under the method’s assumptions. A narrow interval would indicate greater precision than a wide one, but neither an estimate nor an interval is reported for the primary endpoint. A p-value, if available, would address compatibility with a specified null model; it would not establish clinical importance or overcome the limitations of a single-group design. No p-value is reported for this outcome in the registry record.

How should the planning illustrations be read?

The page includes sample-size planning illustrations based on fractions of an observed effect. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such illustrations answer a hypothetical question: under those assumptions, how many participants per arm would be needed to detect an effect of the specified size. They do not describe the enrollment of this single-group study, and they are not observed power.

The assumptions also do not establish that the trial itself used that design or rationale. The actual study has no two-arm randomized comparison in the registry record. Its protocol sample-size justification and planned statistical analysis are not reported in the registry record. A planning calculation based on an observed effect is sensitive to the estimate used; it should be read as an illustration, not as evidence that the observed effect is reliable or that a future study will reproduce it. The registry record does not provide a primary outcome estimate from which readers could independently assess such a calculation.

General statistical context: over-dispersion occurs when observed variability is greater than a model assumes. If present, it can make standard errors and confidence intervals from an overly simple model too optimistic. Whether over-dispersion applies depends on the outcome and analysis. The registry record does not report a fitted model or dispersion assessment for the CD8 endpoint, so no claim about over-dispersion in this study is warranted.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("CY, Nivolumab, GVAX, and SBRT")
n   <- c(13)
m   <- c(5.4)
sp  <- c(0.8)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  CY, Nivolumab, GVAX, and SBRT  13  5.400  0.800  4.917  5.883

11. Multiplicity, Missing Data and Analysis Populations

The registry names CD8+ T-cell density as the primary outcome and pathologic complete response rate at surgical resection as a secondary outcome. It reports 2 outcome measures and 0 analyses. The registry record does not give a multiplicity adjustment, a hierarchy for testing outcomes, or a broader list of planned comparisons. Those details are not reported in the registry record.

As general context, when several outcomes or statistical tests are considered, the chance of at least one apparently notable result can increase if each is interpreted without accounting for the full set of tests. A prespecified primary endpoint can help organize interpretation, but the label alone does not show how multiple testing was handled. Here, no inferential results are available in the registry record, so there is no reported set of p-values or confidence intervals to evaluate for multiplicity.

The primary endpoint population was restricted to participants who received study drug, completed surgical resection, and had sufficient tissue for IHC. The record states that 13 of the 18 treated participants had sufficient tissue for the CD8 analysis. The reasons for unavailable tissue, the number who did not complete surgery, and any imputation or sensitivity analyses are not reported in the registry record. This limits assessment of whether the analyzed tissue subset represents the broader treated group.

The registry lists enrollment of 31, while the endpoint description reports 18 treated participants and 13 with sufficient tissue. These counts describe different populations in the record; the registry does not explain the transition between them. A detailed analysis population definition for the secondary outcome, handling of missing data, and protocol-specified approach to multiplicity are not reported in the registry 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: bile duct stenosis (5.6%), sepsis (5.6%), skin infection (5.6%), weight loss (5.6%).

The adverse-event figures describe the single study group. The record lists 18 participants at risk for serious adverse events and 3 affected. For other adverse events, it lists 18 at risk and 16 affected. The adverse-event group records 0 deaths. These figures are descriptive counts; there is no control group in this study record for a comparative safety estimate.

The serious-event terms listed at the top are bile duct stenosis, sepsis, skin infection, and weight loss, each with a frequency of 5.6%. These are individual entries. They should not be summed to infer a number of unique participants, because the record does not say whether one participant could contribute to more than one term. The terms also do not provide a complete account of event timing, duration, severity grading, or relationship to treatment.

As general context, adverse-event counts depend on how events are defined, collected, and coded, as well as how long participants are observed. The registry record does not provide those details. The count of 0 deaths is the value recorded for this adverse-event group; it should not be expanded into a claim about outcomes outside the registry’s recorded scope. These data describe reported events in this group and do not establish a comparison with another treatment.

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

The registry record establishes that this was a completed phase II, single-group study of a combined approach for borderline resectable pancreatic adenocarcinoma. It describes a primary tissue endpoint: mean CD8+ T-cell density in resected tumor tissue, measured by IHC on a log(cells per mm^2) scale at surgery, approximately 2 months from first dose of study drug. It also records safety counts and identifies pathologic complete response rate at surgical resection as a secondary outcome.

What the record does not establish is the numerical result for the primary endpoint. No mean or standard deviation is reported, and the registry reports 0 analyses. A reader therefore cannot determine from this record the observed CD8 density, its variability, or the precision of an estimated outcome. The numerical result for the secondary outcome is not reported in the registry record either. This is an absence of posted outcome information, not evidence that the endpoint was zero or that no change occurred.

The study’s design also matters. With no randomized comparator, the record cannot provide a like-for-like estimate of how the combined approach compares with another treatment or control. It cannot attribute any outcome to an individual regimen component, particularly because the approach is described as a combination. Nor does the tissue endpoint by itself answer questions about survival, symptoms, or other clinical outcomes.

The safety counts indicate 3 participants affected by serious adverse events among 18 at risk, 16 affected by other adverse events among 18 at risk, and 0 deaths recorded for the adverse-event group. The listed serious-event terms each have a frequency of 5.6%. These data are descriptive and do not establish comparative safety. Overall, the registry record offers information about the study structure, endpoint definition, eligible tissue-analysis population, and recorded adverse events, while leaving the primary numerical outcome and its statistical uncertainty unreported.

14. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a biologically oriented tissue endpoint and a clinical outcome comparison. The primary measure, CD8+ T-cell density in resected tumor tissue, describes immune-cell density in specimens available after treatment and surgery. It can characterize a feature of the sampled tumor tissue, but it is not itself a randomized estimate of treatment benefit. Keeping that distinction clear is important when reading a trial that combines several interventions.

The analysis population also makes the path from enrollment to outcome measurement visible. The record lists enrollment of 31, describes 18 participants as treated, and says 13 had sufficient tissue for CD8 analysis. These are not interchangeable denominators. A tissue endpoint necessarily depends on having a specimen suitable for measurement, and the record makes clear that not all treated participants contributed to this analysis. Without information about why tissue was unavailable or insufficient, the representativeness of the analyzed subset cannot be assessed.

The single-group design is another important statistical feature. It can describe outcomes and adverse events in the study group, but it does not support the same comparative interpretation as a randomized trial with a concurrent control arm. The combination regimen also means that an overall result would not identify which component was associated with an observed pattern.

Finally, the registry record names the primary endpoint but does not report its numerical estimate or an analysis. That gap separates a defined endpoint from an interpretable result. The tables, plots, and planning illustrations should be understood alongside that distinction: planning calculations are hypothetical, while an observed endpoint estimate and its uncertainty would be needed to describe the result directly. The study therefore illustrates why design, analysis population, outcome reporting, and uncertainty all matter alongside an endpoint’s scientific rationale.

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.

Several limitations arise from the registry information available for this study. First, the primary endpoint’s numerical result is not reported in the registry record. The record gives the measure, scale, timing, and standard deviation as the planned dispersion descriptor, but not an observed mean, standard deviation, confidence interval, or test result. The analysis count is listed as 0. The primary endpoint therefore cannot be quantitatively interpreted from this record.

Second, the tissue analysis was limited to participants who received study drug, completed surgical resection, and had sufficient tissue for IHC. The record says 13 of 18 treated participants had sufficient tissue. It does not describe the reasons tissue was unavailable or insufficient, or give an analysis of differences between participants with and without an evaluable specimen. This leaves uncertainty about how well the analyzed subset represents the treated group.

Third, this was a single-group study with no randomized comparator. It cannot support a direct comparative treatment-effect estimate, and the combined approach prevents attribution to any one component. The registry’s enrollment figure of 31 differs from the 18 treated participants described in the outcome population; the record does not explain this difference.

Finally, the registry does not report the protocol’s statistical analysis plan, sample-size justification, interim analyses, missing-data methods, or approach to multiplicity. It identifies a secondary outcome, but its numerical result is not reported in the registry record. The safety counts are descriptive, without a comparator or detailed event-collection information in the record. These limitations concern what can be concluded from the registry record; they do not establish that analyses or information were absent elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: GVAX Pancreas Vaccine (With CY) in Combination With Nivolumab and SBRT for Patients With Borderline Resectable Pancreatic Cancer — NCT03161379.
• Registry record last updated 2025-02-03; status last verified 2025-01.
• Results first posted 2025-02-03.
• 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 completed phase II study enrolled 31 according to the registry record and evaluated a single-group approach for borderline resectable pancreatic adenocarcinoma. The regimen is described as CY, nivolumab, GVAX Pancreas Vaccine, and SBRT; the brief summary also mentions FOLFIRINOX. The primary endpoint was mean CD8+ T-cell density in resected tumor tissue, measured by IHC at surgery on a log(cells per mm^2) scale. Of 18 participants treated on study, 13 had sufficient tissue for the CD8 analysis.

The registry record does not report the primary endpoint’s numerical result and lists 0 analyses. Pathologic complete response rate at surgical resection is listed as a secondary outcome, but its result is not reported in the registry record. The safety record lists 3 participants affected by serious adverse events among 18 at risk, 16 affected by other adverse events among 18 at risk, and 0 deaths. Because this was a single-group study, the posted information does not provide a randomized comparison with another treatment or control.