First-in-Human, Phase 1b/2a Trial of a Multipeptide Therapeutic Vaccine in Patients With Progressive Glioblastoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for First-in-Human, Phase 1b/2a Trial of a Multipeptide Therapeutic Vaccine in Patients With Progressive Glioblastoma (NCT04116658), a non-randomized phase 1, phase 2 study. The primary outcome is Safety and Tolerability of EO2401 Monotherapy, EO2401 in Combination With Nivolumab , EO2401 in Combination With Nivolumab and Bevacizumab.

2. Clinical Question

3. Trial Design

This was a multicenter, open-label, first-in-human phase 1b/2a trial in patients with progressive glioblastoma. The registry describes its allocation as non-randomized and its model as sequential. Participants were assigned to cohorts rather than randomized between comparable treatment arms. The registry lists three regimens: vaccine monotherapy followed by vaccine with nivolumab in Cohort 1, vaccine with nivolumab in Cohort 2, and vaccine with nivolumab and bevacizumab in Cohort 3. The cohort descriptions use the name EO2041, whereas the trial title, primary outcome, and intervention listing use EO2401; the record does not explain this difference.

The study began on 2020-07-13, had a primary completion date of 2024-03-04, and is listed as completed. The registry gives enrollment as 100. The primary safety endpoint covered the period from treatment start through study end, assessed up to 27.5 months. These dates and the endpoint timeframe describe the registry record; they do not establish that every participant had the same follow-up duration.

Because the study was open-label and non-randomized, the cohorts cannot be treated as randomized alternatives. Differences in patient characteristics, treatment exposure, or follow-up could contribute to differences in their event counts. The registry record does not report a formal comparative analysis, randomization procedure, or detailed statistical analysis plan. It also does not report the rationale for the cohort sequence or the sample-size justification.

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

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 Safety and Tolerability of EO2401 Monotherapy, EO2401 in Combination With Nivolumab , EO2401 in Combination With Nivolumab and Bevacizumab, measured over From treatment start up to study end, assessed up to 27.5 months.

The primary endpoint was safety and tolerability, expressed as the count of participants experiencing treatment-emergent serious adverse events. The registry specifies that events were assessed using National Cancer Institute-Common Terminology Criteria for Adverse Events, version 5.0. The observation period ran from treatment start up to study end, assessed up to 27.5 months.

A participant count gives a direct summary of how many people in each cohort experienced at least one event meeting the endpoint definition. It is not a count of all event episodes: a participant may have more than one serious event, but the endpoint is specified in participants. In general, safety endpoints are used in early-phase studies to characterize adverse events observed during exposure and to inform further evaluation of a regimen. This count alone does not describe event duration, severity beyond the serious-event classification, timing, relatedness to treatment, or the number of repeated episodes. Those details are not reported in the registry record for this primary endpoint.

The registry also lists immunogenicity and survival among secondary outcomes. Those outcomes address different questions from the primary safety endpoint and should not be conflated with its participant counts.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The central statistical distinction in this record is between describing outcomes within cohorts and estimating a treatment effect through a comparison. The registry identifies a non-randomized, open-label, sequential study. Its cohort counts therefore describe the experiences recorded under each regimen; they do not have the protection against selection differences that random assignment can provide. A numerical contrast between cohorts, even if calculated, would not by itself isolate the effect of a particular treatment component.

What does a participant count represent?

The primary endpoint is a binary participant-level outcome: whether a participant experienced a treatment-emergent serious adverse event during the specified observation period. A count summarizes participants meeting that condition, rather than the total number of event episodes. If one participant experienced more than one qualifying event, a participant-level count would not represent all of those episodes. The registry does not report event-level totals for the primary endpoint or detail how repeated events were handled beyond specifying the participant count.

Participant counts are straightforward to interpret, but they leave important questions open. They do not show when an event occurred, how long it lasted, whether it recurred, or whether investigators considered it related to treatment. Follow-up can also differ among participants. A count without participant-level time at risk does not adjust for those differences. The endpoint timeframe states that assessment continued from treatment start through study end, up to 27.5 months; the registry record does not report individual follow-up times in the registry record.

Why does non-randomization matter?

Randomization is a design method intended to balance, on average, both measured and unmeasured baseline characteristics across treatment groups. This study was not randomized. Its cohorts received different regimens, including combinations with different medicines, and one cohort had a treatment sequence described as monotherapy followed by combination treatment. Patient characteristics, clinical course, treatment duration, or other factors may differ across these groups. Without a randomized comparison or an appropriate adjusted analysis, observed differences in counts cannot be attributed to a particular regimen.

Open-label treatment means masking was none according to the record. For an outcome based on serious adverse events, knowledge of treatment assignment could affect reporting, assessment, or management in ways that depend on the event and study procedures. This is a general methodological concern, not evidence that such bias occurred in this trial. The registry does not report blinded outcome assessment or procedures intended to address such concerns.

How should uncertainty be understood?

In general, a confidence interval describes the range of values compatible with observed data under a specified statistical model and conveys the precision of an estimate. Event counts from a cohort do not, on their own, show that precision. No confidence intervals or other uncertainty estimates for the serious-event counts are reported in the registry entries. With no posted analyses, readers cannot assess a registry-reported estimate of the uncertainty around these outcomes.

In general, over-dispersion matters when outcome variation exceeds what a chosen model expects; ignoring it can make uncertainty appear too small. The primary endpoint is a participant count, and the record gives no model for such an analysis. Over-dispersion is not identified as a concern or adjustment in the posted record. More broadly, no analysis model, covariate adjustment, or method for handling repeated events is reported.

What do the planning illustrations mean?

The planning illustrations are based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They consider detecting a stated fraction of the observed effect. These are planning assumptions, not the trial’s reported design calculations. The record does not state that the trial was designed using these assumptions, and the illustrations should not be read as observed power. They do not change the fact that the actual study used non-randomized cohorts.

In general, a planning calculation asks how many participants might be needed under specified assumptions to detect an effect of a chosen size with a chosen error rate. Its answer depends on the assumed effect, variability, allocation, outcome type, and analysis method. A calculation using an effect observed in a study is especially illustrative: the observed effect may not be a stable estimate of the effect to expect in a future study. The registry does not report the trial’s own sample-size justification, target power, or design assumptions.

The listed sample-size assumptions describe equal allocation between two arms, while this trial record describes three non-randomized cohorts. Thus the planning illustration is not a reconstruction of this study’s allocation or a test of whether its cohort sizes were adequate. In general, a sample-size calculation cannot repair confounding, selection differences, or the absence of randomization.

What analysis information is absent?

The record lists five outcome measures and zero posted analyses. It does not report a statistical analysis plan, analysis populations, model specifications, multiplicity procedures, missing-data methods, or confidence intervals for the outcomes. These absences limit the ability to evaluate how estimates were defined, how uncertainty was handled, and whether all intended analyses are represented. They do not show that a particular method was used or omitted in study conduct; such details are simply not reported in 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("Cohort 1", "Cohort 2", "Cohort 3")
n      <- c(21, 53, 26)
events <- c(9, 8, 8)
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  Cohort 1  21  9  42.9  21.8  66.0  24.5  63.5  24.4  63.6
ARM  Cohort 2  53  8  15.1  6.7  27.6  7.9  27.1  7.9  27.1
ARM  Cohort 3  26  8  30.8  14.3  51.8  16.5  50.0  16.5  50.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary safety outcome and secondary outcomes that include survival and immunogenicity assessments. It also describes three treatment cohorts and several safety-event categories. When a study evaluates multiple outcomes, groups, or event types, the chance of obtaining an apparently noteworthy result somewhere among them can increase. In general, multiplicity procedures can control or contextualize that issue, depending on the study’s aims. No multiplicity strategy or hierarchy among secondary analyses is reported in the registry record.

The record reports five outcome measures and zero posted analyses. It does not provide a statistical analysis plan that would clarify which outcomes were intended to be confirmatory, how multiple comparisons were to be interpreted, or whether any adjustments were planned. No comparative p-values or confidence intervals are reported in the registry record. The absence of these details means that the registry counts should be treated as descriptive rather than as evidence from a formal hypothesis-testing program.

Missing-data methods and analysis populations are also not reported in the registry record. The record does not state whether all enrolled participants were included in each outcome analysis, how incomplete follow-up was handled, or whether participants without recorded events were treated in a particular way. Because the endpoint spans treatment start through study end, the amount of time observed could matter when interpreting event counts. No participant-level follow-up information is reported for that purpose.

These gaps do not establish that data were missing or that analyses were improperly conducted. They mean that readers cannot assess the consequences of missing observations, the precise analysis population, or how the study handled multiple outcomes. The posted counts remain useful as registry descriptions, but they do not substitute for a prespecified analysis plan or detailed results report.

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: meningitis aseptic (9.5%), condition aggravated (4.8%), radius fracture (4.8%), bone pain (4.8%), brain oedema (4.8%).

The serious adverse-event figures are participant counts within each cohort: 9 of 21 in Cohort 1, 8 of 53 in Cohort 2, and 8 of 26 in Cohort 3. The accompanying other adverse-event counts are 20 of 21, 51 of 53, and 26 of 26, respectively. These are cohort descriptions, not randomized comparisons. The groups received different regimens and may also differ in ways that the registry record does not describe.

The record lists deaths as 20 in Cohort 1, 46 in Cohort 2, and 23 in Cohort 3. It does not report causes, timing, or treatment attribution for these deaths, so those counts should not be interpreted as adverse events caused by treatment. The serious-event term list includes meningitis aseptic at 9.5%; condition aggravated, radius fracture, bone pain, brain oedema, and epilepsy are each listed at 4.8%. The registry record does not specify the relevant denominator or whether these categories overlap.

A count of participants with an event is different from a count of event episodes and does not reveal timing, duration, recurrence, or individual follow-up. The primary endpoint was assessed from treatment start up to study end, up to 27.5 months. Individual exposure and follow-up details are not reported in the registry record. The counts therefore describe recorded safety outcomes without establishing comparative risk or causation.

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

The results describe safety observations in a first-in-human phase 1b/2a study of EO2401 regimens in patients with progressive glioblastoma. They show that the registry recorded serious adverse events and other adverse events in each of the three cohorts. They also include counts of deaths and a short list of serious-event terms with percentages. These are useful descriptive data about what the registry reports, but they are not a controlled estimate of treatment effect.

The study was open-label and non-randomized. The treatment regimens differed across cohorts, and the first cohort included a sequence from monotherapy to combination treatment. Without randomization or a reported adjusted comparison, any difference between cohort counts may reflect differences in participants, exposure, follow-up, or other factors, as well as treatment. The registry provides no basis for assigning a cause to deaths or determining whether an individual event was attributable to treatment.

The primary endpoint addresses safety and tolerability, not efficacy. Survival and immunogenicity are listed as secondary outcomes, but the registry entries do not provide their results. The record therefore does not establish a treatment benefit, nor does it establish lack of benefit. The serious-event counts alone cannot answer whether any regimen improves outcomes or is preferable to another.

The posted data also do not show the precision of event estimates. No confidence intervals, comparative tests, adjusted estimates, or posted analyses are reported. The planning illustrations based on an observed effect are not observed power and do not constitute evidence that the trial was sized to detect a clinically meaningful difference. Readers should distinguish those planning exercises from the actual non-randomized study design.

In general, early-phase studies can characterize observed safety and generate questions for further study. Here, the registry’s counts offer a record of events within these cohorts, while important details about attribution, follow-up, analysis populations, and statistical methods are not reported. The interpretation should remain descriptive and specific to the registry information.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between early-phase safety description and comparative effectiveness evidence. Its primary endpoint is a participant count for treatment-emergent serious adverse events, an outcome suited to describing events observed during exposure. The cohort-level counts provide a compact account of recorded events in a first-in-human setting, but the non-randomized design does not support a straightforward causal comparison among regimens.

The design also illustrates how treatment structure affects interpretation. The cohorts differed not only in which medicines were combined, but Cohort 1 also had a sequence from vaccine monotherapy to continued vaccine with nivolumab. A cohort comparison would therefore mix treatment differences with potential differences in clinical course and time under observation. The registry does not report an analysis that separates these influences.

Another statistical point is the difference between a count and an estimate with quantified uncertainty. The adverse-event counts are reported, but the registry entries include no confidence intervals or posted analyses. Readers can identify the events recorded within each cohort, yet cannot use the record alone to judge the precision of comparative estimates or to evaluate an adjusted model. The number of listed outcomes also makes it important to know how multiple analyses were planned and interpreted; that information is not reported.

The planning assumptions further illustrate that sample-size calculations depend on a specified design. The described illustrations assume equal allocation between two arms, whereas the trial itself had three non-randomized cohorts. Such illustrations can support planning for a future study, but they are not evidence of observed power and do not validate the adequacy of the current cohort sizes.

These features matter because a registry result is most useful when the question, design, outcome definition, and analysis align. Here, the clearest interpretation is descriptive: the registry records safety events in distinct treatment cohorts, while the available information does not establish a comparative treatment effect.

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 specific to this trial affect interpretation of its registry results. First, treatment allocation was non-randomized, and the cohorts received different regimens. The record does not establish that participants in the cohorts were comparable at baseline. Cohort contrasts may therefore reflect patient or treatment-exposure differences rather than effects of the regimen alone. There is no like-for-like randomized control comparison.

Second, the trial was open-label, with no masking. The registry does not describe whether outcome assessment was blinded or how adverse-event reporting was standardized beyond the stated use of NCI-CTCAE v5.0 for the primary safety endpoint. This does not demonstrate that assessment was biased, but the record does not let readers evaluate safeguards against differences in reporting or assessment.

Third, the event counts do not give the timing, duration, recurrence, attribution, or individual follow-up of events. Although the endpoint was assessed up to 27.5 months, the registry does not report whether participants had comparable observation time. The death counts have no reported causes or treatment relationships. The serious-event term percentages lack a stated denominator in the registry entries and may not be mutually exclusive.

The record also contains a naming inconsistency: the trial title and intervention listing identify EO2401, while cohort descriptions use EO2041. It does not explain the discrepancy. In addition, no statistical analysis plan, analysis population, missing-data approach, multiplicity procedure, confidence intervals, or posted analyses are reported. These limitations constrain interpretation of both the safety summaries and any attempt to compare cohorts.

Finally, the record lists survival and immunogenicity as secondary outcomes but does not include their results in the registry record reported. The study’s sample-size justification and detailed protocol rationale are also not reported in the registry record. Conclusions should therefore remain limited to the recorded descriptive safety information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: First-in-Human, Phase 1b/2a Trial of a Multipeptide Therapeutic Vaccine in Patients With Progressive Glioblastoma — NCT04116658.
• Registry record last updated 2025-11-28; status last verified 2025-11.
• Results first posted 2025-11-28.
• 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 NCT04116658 as a completed, multicenter, open-label, first-in-human phase 1b/2a study of EO2401 in patients with progressive glioblastoma. Allocation was non-randomized, and the study model was sequential. Enrollment was 100. The three cohorts evaluated vaccine monotherapy followed by nivolumab combination treatment, vaccine with nivolumab, and vaccine with nivolumab plus bevacizumab; the cohort descriptions spell the vaccine name as EO2041.

The primary outcome was the participant count for treatment-emergent serious adverse events, assessed from treatment start through study end, up to 27.5 months, using NCI-CTCAE v5.0. Registry safety counts include serious and other adverse events, deaths, and selected serious-event terms. Survival and immunogenicity are listed as secondary outcomes. No statistical analyses are posted in the registry record, and comparative estimates, analysis methods, missing-data procedures, and multiplicity methods are not reported. The safety counts are descriptive and do not establish causal differences between regimens.