Vacc-4x + Lenalidomide vs. Vacc-4x +Placebo in HIV-1-infected Subjects on Antiretroviral Therapy (ART): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vacc-4x + Lenalidomide vs. Vacc-4x +Placebo in HIV-1-infected Subjects on Antiretroviral Therapy (ART) (NCT01704781), a randomized phase 1, phase 2 study. The primary outcome is Part A: To Establish Highest Tolerated Dose of Lenalidomide, Dose-Limiting Toxicity.

2. Clinical Question

The study title frames lenalidomide as an addition to Vacc-4x, with the comparator receiving placebo alongside Vacc-4x. The registry record’s posted primary outcome, however, concerns the Part A dose-escalation assessment, not a comparative estimate of the effect of lenalidomide versus placebo. The record describes the study as randomized and parallel, and its official title describes a double-blind placebo-controlled study with an initial open-label dose-escalation assessment. The registry lists quadruple masking overall. How masking was applied to each component is not reported in the registry record.

The study’s stated objective is to assess whether adding lenalidomide could support Vacc-4x’s intended immune response to HIV p24. That is the rationale recorded for the study, not a result. The posted primary result addresses dose-limiting toxicity; it does not directly report an immune-response endpoint. The registry lists further secondary outcomes, but the result details for those outcomes are not reported in the registry record.

3. Trial Design

The registry describes NCT01704781 as a randomized, parallel, Phase 1 and Phase 2 study with quadruple masking and an enrollment of 36. Its status is completed. The official title calls it a double-blind placebo-controlled immunogenicity study and specifies an initial open-label dose-escalation assessment. These descriptions indicate that the record includes distinct study components: an open-label dose-escalation assessment in Part A and a placebo-controlled comparison in Part B.

Part A is described as a 3+3 dose-escalation design. Participants received intradermal Vacc-4x at 1.2 mg with rhuGM-CSF at 0.06 mg and oral lenalidomide. The listed groups are 5 mg, 10 mg and 25 mg; the record also describes 2.5 mg as a dose level in the event that the starting level is not tolerated. The posted primary outcome is the number of participants in each of the three groups who experienced any dose-limiting toxicity over 31 days. The registry does not provide the operational criteria for a dose-limiting toxicity.

Part B compares Vacc-4x with rhuGM-CSF and lenalidomide against the same background treatment with lenalidomide placebo. The arm descriptions specify 6 immunizations and oral study medication two days before and on the day of immunization. The lenalidomide dose was determined in Part A. The registry lists secondary outcomes concerning CD8 count, HIV viral load, delayed-type hypersensitivity, and safety and tolerability.

The posted result groups for the primary outcome are Part A dose groups. They do not constitute a direct estimate of the Part B lenalidomide-versus-placebo contrast. Details such as the randomization procedure, allocation concealment, the masking procedures by study part, and the intended sample-size justification 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

Analysis population for the primary outcome, as defined in the registry: ITT analysis set was used.

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 Part A: To Establish Highest Tolerated Dose of Lenalidomide, Dose-Limiting Toxicity, measured over 31 days.

The primary endpoint is a count: the number of participants in each Part A dose group who experienced any dose-limiting toxicity during the specified 31-day timeframe. The registry states that the intention-to-treat (ITT) analysis set was used. The posted counts are 0 in the lenalidomide 5 mg group, 0 in the 10 mg group and 0 in the 25 mg group. The corresponding group sizes are 3, 3 and 6.

In a dose-escalation assessment, dose-limiting toxicity is used to characterize whether treatment-related toxicity meets a prespecified threshold over a defined observation period. General statistical context: this kind of endpoint can inform dose selection because it focuses on the occurrence of an event rather than on an average measurement. The registry record does not report the toxicity criteria, how events were attributed, or how the observations were used to select a dose. It therefore supports description of the posted counts, but not reconstruction of the dose-selection decision.

All three posted counts are zero, but the groups are small. A zero count means that no dose-limiting toxicity was recorded in those group results; it does not establish that the underlying risk is zero. The record does not provide confidence intervals or another quantified measure of uncertainty for these counts. This endpoint also differs from the immunogenicity objective described in the study title: the posted primary outcome does not itself quantify an immune response to HIV p24.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry posts a binary event count for the primary outcome: whether a participant experienced any dose-limiting toxicity during 31 days. The reported summary is the number of participants with an event in each dose group. This is a count endpoint, not a continuous measurement such as a laboratory value and not a time-to-event summary. The listed primary analysis population is ITT, although further details about how that population was defined or handled are not reported in the registry record.

What does a count show?

A count gives the observed number of participants meeting the endpoint definition in a group. For Part A, the posted counts are 0 for lenalidomide 5 mg, 0 for 10 mg and 0 for 25 mg. Group sizes are 3, 3 and 6, respectively. General statistical context: counts are especially easy to interpret, but the same count can have different implications depending on the group size and on how completely the outcome was observed. A zero count describes the observations; it is not evidence that the event can never occur. The registry does not report confidence intervals or another uncertainty interval for the primary counts.

Why is an interval useful?

General statistical context: a confidence interval describes the range of effect estimates compatible with the observed data under a specified statistical procedure. It helps distinguish a point estimate from its precision. For sparse binary outcomes, an interval can be wide even when the observed count is zero, because a small group cannot rule out events that were not observed. No such interval is reported for the posted primary endpoint, and one should not infer precision from the zero counts alone.

Why is a direct comparison unavailable?

The posted primary outcome is organized around three Part A dose groups. The registry does not provide a usable two-arm estimate for this binary endpoint, and the posted analysis record has no inferential analyses. The comparison of interest in the study title—lenalidomide versus placebo with Vacc-4x—is a Part B question, whereas the primary result shown is the Part A dose-escalation outcome. A valid treatment comparison would require results and an analysis appropriate to the Part B groups. A difference between observed counts, or a ratio of those counts, is not a substitute for a prespecified comparative analysis. No recalculated effect estimate is posted for this endpoint.

What role does the dose-escalation design play?

The registry describes Part A as a 3+3 dose-escalation design. General statistical context: dose-escalation designs use observations at successive dose levels to guide decisions about further dosing, with the specific rules depending on the protocol. The registry lists dose groups and a primary toxicity outcome, but it does not report the full decision rules, toxicity grading criteria, or rationale for the dose levels. The observed zero counts therefore cannot be used to reconstruct the dose-selection procedure or establish what dose the investigators considered acceptable.

How should the sample-size illustrations be read?

General statistical context: sample-size planning depends on the effect a study is intended to detect, the chosen significance level, allocation, and assumptions about the outcome. The planning illustrations associated with the posted results are based on the observed effect, use a two-sided significance level of 0.05, equal allocation, and a normal approximation; the illustration varies the fraction of the observed effect targeted. These are planning illustrations, not observed power and not evidence about the probability that the trial detected an effect. Their numeric planning values are not reported in the registry record. The registry’s own sample-size justification and the assumptions used for its original design are not reported in the registry record.

General statistical context: over-dispersion matters when variability in count data exceeds what a chosen model assumes, because it can make standard errors too small and uncertainty appear narrower than it is. The primary endpoint is presented as a participant count in small groups, and no count model, dispersion estimate, or model-based analysis is reported. It would therefore be inappropriate to attribute an over-dispersion adjustment or another model to the trial.

For the adverse-event results, the registry reports participant counts with serious and other adverse events by group. These summaries do not quantify time at risk, provide event-level detail for every event, or establish treatment causality. The listed serious-event term and percentage should be read as a registry report, not as a comparative estimate. Methods for coding adverse events, assessing severity, and determining relatedness are 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("Part A: Lenalidomide 5 mg", "Part A: Lenalidomide 10 mg", "Part A: Lenalidopmide 25 mg")
n      <- c(3, 3, 6)
events <- c(0, 0, 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  Part A: Lenalidomide 5 mg  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2
ARM  Part A: Lenalidomide 10 mg  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2
ARM  Part A: Lenalidopmide 25 mg  6  0  0.0  0.0  45.9  0.0  39.0  0.4  41.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists several outcomes in addition to the primary endpoint: change in CD8 count, effect on HIV viral load, delayed-type hypersensitivity, and safety and tolerability. It does not report a multiplicity procedure for interpreting results across these outcomes. Whether any adjustment was planned, or whether outcomes had a prespecified testing hierarchy, is not reported in the registry record. Without that information and outcome-specific results, the listed secondary outcomes cannot be treated as confirmed findings.

The primary outcome description identifies the ITT analysis set. The record does not explain how participants were included in that set, whether all assigned participants had outcome data, or how missing outcome information was handled. Missing-data methods, imputation procedures, and sensitivity analyses are not reported in the registry record. The number of participants with missing primary outcome data is also not reported in the registry record.

The registry posts zero dose-limiting toxicity counts in all three Part A groups, but those counts do not disclose whether every participant was followed for the full 31-day timeframe. The record does not state how incomplete follow-up, withdrawal, or other deviations were addressed. This matters because an unobserved outcome is not equivalent to an observed absence of toxicity.

The registry reports no inferential analyses for the primary result, and a two-arm comparison for this binary endpoint is not available from the posted values. The statistical analysis plan, including any planned interim analyses or multiplicity strategy, is not reported in the registry record. The absence of these details does not establish that a procedure was or was not used; it limits what can be inferred from the posted registry results.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

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: abscess left upper arm (8.3%).

Serious adverse-event counts are reported separately by study group. In Part A, the counts are 0 among 3 participants in the 5 mg group, 0 among 3 in the 10 mg group, and 0 among 6 in the 25 mg group. In Part B, the count is 1 among 12 participants receiving lenalidomide and 0 among 12 receiving placebo. These are counts of participants affected, not a measure of treatment causality.

The registry also reports other adverse events: 3 participants in Part A’s 5 mg group, 2 in the 10 mg group, and 6 in the 25 mg group; in Part B, 10 participants in the lenalidomide group and 9 in the placebo group. Serious and other adverse events are different categories in the registry record and should not be combined into a single outcome. The registry does not provide enough detail to determine whether the same participants experienced events in both categories.

The record lists Abscess left upper arm as a serious adverse-event term with 8.3%, but the posted details do not clearly identify its treatment group. Death counts are not reported in the registry record. These safety summaries are descriptive and do not establish whether an event was caused by treatment or whether groups differ reliably in safety.

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

The posted primary result establishes a limited descriptive fact: no dose-limiting toxicity was recorded in the Part A lenalidomide 5 mg, 10 mg or 25 mg groups during the stated 31-day timeframe. The result is consistent with the absence of observed events in these groups. It does not establish that dose-limiting toxicity is impossible, that a larger group would have the same experience, or that one dose has the same safety profile as another.

These data also do not provide a direct estimate of the effect of adding lenalidomide to Vacc-4x compared with placebo. The primary endpoint concerns dose-limiting toxicity during Part A dose escalation, while the placebo-controlled comparison is Part B. The registry does not post an inferential two-arm analysis for the binary primary endpoint. The one serious adverse event reported in Part B’s lenalidomide group and none in the placebo group are descriptive counts, not proof of a treatment-related difference.

The study is framed around immunogenicity, but the primary result is a toxicity count. The registry names secondary outcomes concerning CD8 count, HIV viral load, delayed-type hypersensitivity, and safety and tolerability; their outcome results are not reported in the registry record. The primary result therefore does not show whether the intended immune response changed or whether viral load changed.

General statistical context: a result is more informative when its endpoint, comparison, uncertainty, and analysis population are all clear. Here, the endpoint and primary analysis population are identified, but the record does not provide an uncertainty interval, complete analysis details, or a primary comparative estimate. The results should be interpreted as registry-reported observations rather than as a definitive estimate of benefit or harm. They do not support medical advice or a conclusion about treatment effectiveness.

14. Why This Trial Matters Statistically

This trial illustrates why the endpoint and study component must be identified before interpreting a result. The title emphasizes a placebo-controlled comparison of Vacc-4x with lenalidomide versus Vacc-4x with placebo, while the posted primary endpoint is a Part A dose-escalation toxicity count. The count addresses a dose-selection and safety question; it is not a direct measure of immunogenicity and is not the Part B treatment contrast.

The record also demonstrates the limits of sparse event data. Zero dose-limiting toxicities were reported in each Part A group, but the group sizes are small and no uncertainty intervals are posted. A count of zero may appear conclusive at a glance, yet it only describes the observed group during the specified timeframe. It cannot by itself establish the frequency of an uncommon event in a broader population.

Another statistical lesson is that descriptive arm data do not automatically constitute a comparative analysis. Part B has adverse-event counts for lenalidomide and placebo, but no inferential analysis is recorded for the primary binary endpoint. Those counts should not be converted into a treatment-effect claim. An estimate and its uncertainty require a suitable analysis and clearly defined outcome data.

Finally, a trial can have an immunogenicity rationale while its posted primary result reports toxicity. The registry’s listed secondary outcomes give context about the intended scope, but their results are not reported in the registry record. Clear separation of rationale, endpoint, study part, and posted result is essential to avoid attributing a finding to a question it does not answer.

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 primary result is based on small Part A groups, with 3 participants in the 5 mg group, 3 in the 10 mg group and 6 in the 25 mg group. The zero counts are descriptive, and no confidence intervals or other uncertainty estimates are reported. The registry does not state whether all participants completed the 31-day observation period or how missing outcome information was handled.

The primary outcome’s operational definition is incomplete in the record. The registry names dose-limiting toxicity but does not report its criteria, severity threshold, attribution rules, or the dose-escalation decision rules. The listed dose groups alone cannot establish how the study selected a dose for Part B.

The primary result comes from Part A and does not provide a direct lenalidomide-versus-placebo estimate for Part B. The record does not post an inferential primary analysis, and comparative values for the binary endpoint are missing or not estimable. The statistical analysis plan, sample-size justification, handling of multiplicity, and interim-analysis approach are not reported in the registry record.

The registry lists secondary outcomes but does not report their results in the available record. Participant eligibility details, baseline characteristics, and outcome-specific missingness are not reported in the registry record. Safety reporting is also limited: the serious-event term with 8.3% is not clearly linked to a group in the posted details, and death counts are not reported in the registry record. These limitations restrict interpretation to the descriptive information recorded, rather than a precise comparative assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Vacc-4x + Lenalidomide vs. Vacc-4x +Placebo in HIV-1-infected Subjects on Antiretroviral Therapy (ART) — NCT01704781.
• Registry record last updated 2017-03-08; status last verified 2014-10.
• Results first posted 2017-03-08.
• 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

NCT01704781 is a completed randomized, parallel Phase 1 and Phase 2 study of Vacc-4x with lenalidomide versus Vacc-4x with placebo in HIV-1-infected subjects on ART. The registry lists quadruple masking and an enrollment of 36. The official title describes a placebo-controlled immunogenicity study with an initial open-label dose-escalation assessment.

The posted primary endpoint is the number of Part A participants with any dose-limiting toxicity during 31 days, analyzed in the ITT set. The reported counts are 0 in each of the 5 mg, 10 mg and 25 mg lenalidomide groups. No inferential analysis or comparative estimate for this binary endpoint is reported. Part B adverse-event counts include 1 serious adverse event in the lenalidomide group and 0 in the placebo group.

The record lists secondary outcomes, but their results, the statistical analysis plan, missing-data methods, and sample-size justification are not reported in the registry record. The primary counts are descriptive and do not answer the study’s comparative immunogenicity question.