Vaccine Plus Booster Shots in Men With Prostate Cancer Undergoing Treatment With Radical Prostatectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vaccine Plus Booster Shots in Men With Prostate Cancer Undergoing Treatment With Radical Prostatectomy (NCT02153918), a na phase 2 study. The primary outcome is Changes From Baseline to After Surgery of Cluster of Differentiation 4 (CD4) and Cluster of Differentiation 8 (CD8) Cell Infiltrates.

2. Clinical Question

The study examined whether a vaccine prime followed by booster shots before radical prostatectomy was associated with changes in immune-cell infiltrates in prostate tissue. Its primary question focused on CD4 and CD8 cells in tissue collected before vaccination and after surgery, at approximately week 10. The registered outcome describes quantifying stained cells and comparing pre- and post-vaccination values.

The clinical context in the registry record is men with prostate cancer that had not spread who planned to have their prostate glands removed. The study was intended to examine an immune response in the prostate, rather than to compare clinical outcomes between vaccine-treated and untreated groups. The record's background mentions interest in recurrence, but recurrence is not the primary outcome listed. A recurrence result is not reported in the registry record.

The intervention was a sequence of PROSTVAC-V/TRICOM followed by PROSTVAC-F/TRICOM boosts before surgery. The record describes the booster timing in two ways: the summary refers to three boosters over several weeks, while the arm description says boosts were given monthly until radical prostatectomy or stopping therapy. The registry does not report a control group receiving no vaccine or another treatment. Consequently, the primary question is about pre- to post-treatment tissue measurements in the enrolled group, not a randomized treatment contrast.

3. Trial Design

This was a phase II study sponsored by the National Cancer Institute (NCI). The registry describes a single-group model, no masking, and allocation as not applicable. The study enrolled 27 participants. It began on 2014-05-31, had primary completion on 2017-07-28, and is listed as completed.

Eligible participants were men age 18 and older with prostate cancer that had not spread and who wanted prostate removal as treatment. The study used a neoadjuvant approach: vaccination occurred before the planned radical prostatectomy. Participants received PROSTVAC-V/TRICOM followed by PROSTVAC-F/TRICOM. The arm description says the booster was given monthly until surgery or until therapy was stopped; the brief summary describes three booster injections over several weeks. The registry record does not clarify this difference in wording.

The registered primary outcome was the change from baseline to after surgery in CD4 and CD8 cell infiltrates. Baseline is described as before vaccination, and the post-treatment assessment as approximately week 10. Prostate biopsy specimens were stained for CD4 and CD8 cells, with computer-automated analysis used to quantify stained cells. The record says only 26 participants had tissue available for analysis.

Secondary outcomes covered peripheral PSA-specific T-cell responses, intraprostatic regulatory T-cell infiltration, PSA changes, MRI changes, and adverse events assessed using CTCAE v4.0. The registry lists six outcome measures in total, consistent with one primary outcome and five secondary outcome topics. It does not report a randomized control arm, a masking procedure, or an analysis record. Details such as the protocol's sample-size justification, interim analyses, and the statistical analysis plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Only 26 participants had available tissue for 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 Changes From Baseline to After Surgery of Cluster of Differentiation 4 (CD4) and Cluster of Differentiation 8 (CD8) Cell Infiltrates, measured over Baseline (pre vaccination) and approximately week 10.

The primary endpoint concerns changes in CD4 and CD8 cell infiltrates in prostate tissue from before vaccination to after surgery, at approximately week 10. These immune cells were assessed in prostate biopsy specimens stained for CD4 and CD8. The description says the number of stained cells was quantified using computer-automated staining analysis and that cell density was calculated before and after vaccination. The registered summary statistic is the median, with the inter-quartile range as the measure of dispersion.

In general, a tissue-based endpoint can describe a biological response in the organ where the disease is being treated. Here, the endpoint is intended to characterize immune-cell infiltration in prostatectomy specimens after a neoadjuvant vaccine regimen. It is not, by itself, a measure of whether cancer recurred, whether survival changed, or whether a clinical outcome differed from what would have occurred without vaccination.

The registry lists the unit as Cell/mm(2), while the outcome description refers to cells per micron squared of surface area. Those descriptions do not use the same area unit, so the scale should be interpreted cautiously unless clarified elsewhere. Numerical medians, inter-quartile ranges, and changes for CD4 and CD8 are not reported in the registry record. As a result, the size and direction of the measured tissue changes cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome using a median and inter-quartile range. In general, the median is the middle value when observations are ordered. The inter-quartile range describes the spread across the middle half of the observations. These summaries can be useful when measurements are skewed or have influential extreme values, because the median is less sensitive to extremes than the mean. The choice of summary alone does not show the distribution of the data or establish whether the observed change is statistically distinguishable from no change.

What does a before-and-after comparison estimate?

For each tissue marker, the endpoint compares a pre-vaccination measurement with a measurement after surgery. In general, a paired analysis uses both observations from the same participant and focuses on within-person change. Pairing can account for stable differences between participants because each person serves as their own reference. However, the registry record does not report the exact analysis used to compare CD4 or CD8 measurements, whether the comparison was performed on individual paired changes, or how those changes were summarized beyond listing the median and inter-quartile range.

The record says tissue was available for 26 participants. In general, a paired analysis requires both measurements for a participant. The record does not specify whether all 26 had both baseline and post-surgery tissue measurements, how missing measurements were handled, or whether any participants were excluded from the endpoint analysis for other reasons. The primary endpoint description says pre- and post-vaccination values would be compared, but the analytic details and numerical results are not reported in the registry record.

What does the single-group structure imply?

The registered design has one group receiving the vaccine regimen and no separate control group. In general, a within-group change is not equivalent to a treatment effect relative to a comparator. A change between baseline and follow-up may be temporally associated with the regimen, but the study design by itself cannot distinguish that change from changes that might have occurred without the regimen. A randomized comparison can help estimate a between-group contrast under its design assumptions; this record does not list such a comparison.

The study is described as unmasked. In general, masking can limit the influence of knowledge about treatment assignment on some aspects of care, assessment, and reporting. The record lists masking as none but does not say whether laboratory personnel who quantified stained cells were masked to specimen timing or participant information. That detail is not reported in the registry record and should not be assumed.

How should uncertainty be understood?

In general, a confidence interval gives a range of values compatible with the data and the method used, and its width communicates precision. A point estimate without an interval gives less information about uncertainty. The registry record provides no confidence intervals for the primary tissue changes, so their precision cannot be judged from the posted outcome information. A p-value, if available, would address a different question about compatibility with a specified statistical null model; it would not by itself describe the size or clinical meaning of a change. No primary outcome p-value is reported in the registry record.

The number of enrolled participants and the number with available tissue describe the scale of the observed study, but neither is a substitute for an estimate with uncertainty. In general, small datasets can yield imprecise estimates, though the actual precision depends on the observed values and their variability. Those values and variability summaries are not reported for the primary outcome.

What do the planning assumptions mean?

The record's planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The calculation is framed around detecting a stated fraction of an observed effect. In general, a planning calculation estimates a sample size under specified assumptions about the effect and variability; it is not evidence that a study had a particular probability of finding a result after data collection. The stated calculations are planning illustrations, not observed power.

Those assumptions describe a hypothetical two-arm allocation, whereas this trial is registered as a single-group study with allocation not applicable. They therefore should not be read as a description of the actual enrollment strategy. The registry record does not report the trial's own sample-size justification, the effect size or variability used in its design, or a protocol-based power calculation. Numerical planning outputs are not reported in the registry record.

Why can over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a statistical model expects. If a model understates variability, standard errors may be too small and uncertainty intervals or tests may be misleading. This is a general issue for count-like or clustered measurements, not a reported finding in this study. The registry record does not identify an over-dispersion assessment or a model for the cell-count measurements, so no conclusion about its presence or handling is possible.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures: the primary CD4 and CD8 tissue-infiltrate outcome and five secondary outcome topics. Those secondary topics include peripheral PSA-specific T-cell responses, intraprostatic regulatory T-cell infiltration, PSA changes, MRI changes, and adverse events. The registry record does not report numerical analyses for these outcomes or any analysis records.

In general, testing several outcomes can increase the chance of at least one apparently notable finding if each is assessed separately. Statistical plans may address this through a prespecified hierarchy, adjustment, or a distinction between confirmatory and exploratory outcomes. The registry record does not report a multiplicity strategy, a hierarchy among the secondary outcomes, or whether adjustments were planned or used. It is therefore not possible to determine how multiple outcome assessments were intended to affect interpretation.

The primary tissue analysis was limited to 26 participants with available tissue, while 27 participants enrolled. The record does not give the reason tissue was unavailable, the amount of missingness for other outcomes, or the method used to handle missing data. In general, missingness can affect interpretation if the participants with observed measurements differ in meaningful ways from those without measurements. Whether that occurred is not reported in the registry record.

The registry does not define an intention-to-treat population, a per-protocol population, or another formal analysis population. It also does not describe exclusions, protocol deviations, or the population used for each secondary outcome. The available-tissue count is the only stated population detail for the primary endpoint. These omissions limit assessment of which participants contributed to each result and whether the analysis population followed a prespecified plan.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: thromboembolic event (3.7%).

The registry lists 27 participants at risk for serious adverse events and 1 participant affected. For other adverse events, 27 were at risk and 27 were affected. The listed number of deaths is zero. These are participant counts in the registry's single vaccine-plus-booster group; they are not comparisons against an untreated or alternative-treatment group.

The top serious adverse event term is thromboembolic event, reported as 3.7%. The registry does not give a separate event count for that term in the information summarized, nor does it state whether the event or events were judged related to vaccination, surgery, or another cause. The term should therefore be read as a reported serious-event category, not as proof of causation.

In general, an adverse event is an observed health event during a study and is not necessarily caused by the study treatment. Seriousness is a regulatory classification and is distinct from how intense or bothersome an event was. The registry says adverse events were assessed using CTCAE v4.0, but details on grading, attribution, timing, and event-level counts are not reported in the registry record. With no comparison group, these counts describe events in the enrolled group and cannot establish relative risk.

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

The record establishes that a phase II, single-group study evaluated a neoadjuvant PROSTVAC-V/TRICOM and PROSTVAC-F/TRICOM regimen in men planning radical prostatectomy. It identifies a tissue-based primary outcome: CD4 and CD8 cell infiltrates before vaccination and after surgery, at approximately week 10. It also identifies secondary topics involving immune responses, PSA, MRI, and adverse events. These details clarify what the study set out to measure.

The registry record does not report the numerical primary outcome values or the secondary outcome results. It therefore does not show whether CD4 or CD8 infiltrates increased, decreased, or remained similar, nor how precise any change estimate was. It also does not report a recurrence result, despite mentioning recurrence in the study background. The absence of posted numerical results in this record should not be converted into a claim that there was no effect or that an effect was established.

The design limits causal interpretation. With one treated group and no listed control group, the pre- and post-surgery measurements do not provide a direct estimate of what would have happened without the vaccine regimen. Even if numerical changes were available, attributing them specifically to vaccination would require caution. The posted record also does not give the statistical analysis plan, missing-data procedures, or confidence intervals needed to evaluate the analysis in detail.

The safety entries show that adverse events were recorded among participants, including one participant with a serious adverse event and zero deaths. They do not establish that the regimen caused an event or that its safety differed from another approach. The serious-event term and the 3.7% entry are descriptive information from the study group.

Accordingly, the registry information supports a description of the trial question, design, outcome definitions, and available safety counts. It does not support a numerical conclusion about the primary immune-cell outcome, clinical benefit, recurrence, or comparative safety. Those results and their uncertainty are not reported in the registry record.

13. Why This Trial Matters Statistically

Statistically, this study illustrates the distinction between measuring a biological response and estimating a comparative treatment effect. The primary outcome is a tissue measurement before and after a neoadjuvant regimen. Such measurements can characterize change among participants with available specimens, but the single-group design does not include a concurrent control group to separate treatment-associated change from other changes over time.

The endpoint also depends on tissue availability and measurement. The primary analysis population is reported as 26 participants with available tissue, out of 27 enrolled. The record does not explain the unavailable specimen or provide enough detail to assess how representative the analyzed tissue was. It also uses different area units in the endpoint's unit label and description, which makes clear measurement reporting important for interpretation and replication.

The outcome set spans tissue immunology, peripheral immune response, PSA, imaging, and adverse events. In general, evaluating several outcomes raises questions about which outcomes are primary, how multiplicity is handled, and which analyses are confirmatory. The record identifies a primary outcome and secondary topics but does not report a multiplicity strategy or numerical analyses. This makes the outcome framework visible while leaving the inferential plan and results unclear.

Finally, planning calculations based on a two-arm allocation do not describe the registered single-group design. The distinction is important: planning assumptions are not observed power, and hypothetical sample-size calculations do not substitute for the actual analysis or its uncertainty. The study record is therefore useful for understanding the type of biological question pursued, while also showing why design, endpoint units, missing specimens, and complete outcome reporting are central to statistical interpretation.

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 principal limitation for interpreting the posted outcomes is that numerical primary and secondary results are not reported in the registry record. Without endpoint estimates, dispersion measures, confidence intervals, or p-values, the direction, magnitude, and precision of the primary immune-cell changes cannot be assessed. The record has no analysis records, leaving the statistical implementation and results unavailable in the registry.

The single-group structure provides no concurrent control comparison. Any pre- to post-treatment difference would describe change in the observed group, not a controlled estimate of the effect attributable to vaccination. The record also lists no masking, and it does not say whether tissue quantification was performed without knowledge of assessment timing or other participant details.

Only 26 participants had tissue available for analysis, compared with 27 enrolled. The reason for unavailable tissue, the handling of incomplete measurements, and the characteristics of participants contributing to the endpoint are not reported. The record does not define the analysis population or describe protocol deviations. Thus, the extent to which the tissue analysis represents all enrolled participants cannot be evaluated.

There is a unit inconsistency in the primary outcome description: the listed unit is Cell/mm(2), while the description states cells per micron squared of surface area. The registry does not clarify the intended unit. It also describes booster timing both as three boosters over several weeks and as monthly boosts until surgery or stopping therapy; the record does not reconcile these descriptions.

Finally, the registry does not report the statistical analysis plan, the trial's sample-size justification, interim analyses, multiplicity handling, or missing-data methods. These omissions restrict assessment of whether analyses followed prespecified procedures and how the outcomes were intended to be interpreted.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Vaccine Plus Booster Shots in Men With Prostate Cancer Undergoing Treatment With Radical Prostatectomy — NCT02153918.
• Registry record last updated 2018-10-12; status last verified 2018-09.
• Results first posted 2018-10-12.
• 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

NCT02153918 is a completed phase II, single-group study sponsored by the National Cancer Institute (NCI). It enrolled 27 men with prostate cancer who were planning radical prostatectomy and evaluated PROSTVAC-V/TRICOM followed by PROSTVAC-F/TRICOM before surgery. The primary outcome concerned changes in CD4 and CD8 cell infiltrates in prostate tissue from baseline to after surgery, at approximately week 10.

Tissue was available for analysis for 26 participants. The record lists five secondary outcome topics covering immune responses, intraprostatic regulatory T cells, PSA, MRI, and adverse events. It reports one participant with a serious adverse event, 27 with other adverse events, and zero deaths; the top serious-event term is thromboembolic event at 3.7%.

Numerical primary and secondary outcome results, confidence intervals, p-values, detailed analysis methods, and missing-data procedures are not reported in the registry record. The single-group design has no listed control arm, so the record does not provide a randomized treatment comparison.