CAVATAK in Patients With Stage IIIc or IV Malignant Melanoma to Extend Dosing to 48 Weeks (VLA-008 CALM Ext): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for CAVATAK in Patients With Stage IIIc or IV Malignant Melanoma to Extend Dosing to 48 Weeks (VLA-008 CALM Ext) (NCT01636882), a na phase 2 study. The primary outcome is Safety.

2. Clinical Question

In statistical terms, this is primarily a descriptive question: what adverse events were recorded among the participants in this extension? Without a concurrent control group, the study cannot directly estimate how those counts compare with what would have occurred under another treatment or without the extension regimen. Its intended population is also selected from people who had already received treatment in an earlier study, so the findings describe this extension cohort rather than all people with melanoma.

3. Trial Design

NCT01636882 was a Phase 2, completed, single-group study sponsored by Viralytics. The registry lists enrollment of 16 participants, the condition as melanoma, and the intervention as CVA21. The study was designed as an extended-use study for patients who had received 10 doses of CAVATAK in the VLA 007 trial. The stated purpose was to make additional treatment available to complete up to 48 weeks of intratumoral injections.

The recorded CVA21 regimen was a dose up to 3 × 10⁸ TCID50 for an additional 9 treatments at 3-week intervals. Those details describe the intended regimen; the registry record does not report individual treatment histories, adherence, dose modifications, or the number of participants who completed the planned schedule. The design does not include a concurrent control arm. Allocation is recorded as not applicable, masking as none, and the model as single group.

The registry lists the study start as 2012-07-03, primary completion as 2016-04-06, and status as completed. The primary outcome was safety, measured as participants with Grade 3 or Higher Adverse Events over 12 months. Although the record lists one outcome measure, it lists no analyses and does not post a primary-endpoint result. The registry record does not report the statistical analysis plan, the endpoint’s detailed assessment rules, or the sample-size justification.

Because this was an extension following prior treatment, it differs from a trial enrolling a broader treatment-naive population. Entry depended on prior participation and receipt of treatment in VLA 007, and the brief description frames further treatment as intended for patients who might benefit. The record does not report the selection process or how many people were considered for enrollment. These design features matter when deciding how far the safety observations can be generalized.

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: Subjects were screened for and excluded from the study if they had pre-existing antibodies to CVA21.

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, measured over 12 months.

The primary endpoint was the number of participants with Grade 3 or Higher Adverse Events during a 12-month timeframe. It is a count of participants meeting an event criterion, not a measure of the number of all adverse-event episodes, their duration, or their total severity burden. The registry does not provide further details about how event severity was graded, how events were attributed, or how the endpoint was assessed over time.

Safety endpoints are used to describe harms observed during treatment and follow-up. Counting participants who experience events at or above a specified severity threshold can make the endpoint easier to interpret than a list of every event, while retaining a focus on more severe events. That general rationale does not establish that the endpoint captures every safety concern: event definitions, ascertainment, exposure, and follow-up all affect what is counted.

The registry record does not post a result for this primary endpoint. It does report counts for serious adverse events, other adverse events, and deaths. Those categories are not interchangeable with participants having Grade 3 or Higher Adverse Events. Seriousness and severity are distinct classifications in general, and the record does not provide enough detail to determine how the posted adverse-event categories map onto the primary endpoint. The posted counts therefore should be read as separate safety information, not as the missing primary-endpoint result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What a single-group study estimates. A single-group study records outcomes among participants receiving the study intervention. In general, its direct statistical description is the observed experience of that group. Without a concurrent comparator, it does not estimate a randomized between-group contrast. The CVA21 extension is recorded as single-group, with allocation not applicable and no masking. Therefore, safety counts can describe events in the cohort, but they cannot by themselves establish how those counts differ from another treatment group or from an untreated counterfactual.

Counts of participants and event counts. The primary endpoint is defined as participants with Grade 3 or Higher Adverse Events, with participants as the unit. A participant-based endpoint counts people meeting the event definition, rather than counting every episode. In general, one participant may experience more than one event; a participant count and an event count answer different questions. The registry does not post the primary-endpoint result, and it does not give event-level data that would permit a separate reconstruction. The serious and other adverse-event figures are posted as participant counts for the CVA21 group.

Severity and seriousness. In general, severity describes the intensity or grade of an event, whereas seriousness is a separate classification based on regulatory or clinical criteria. An event may be serious without necessarily being described by a particular severity grade, and the terms should not be treated as synonyms. The primary endpoint uses a severity threshold, while the posted safety summary separately identifies serious adverse events. The registry record does not provide the grading details or a mapping between these categories, so one cannot infer the primary-endpoint count from the serious-event count.

Interpreting proportions and uncertainty. A participant count with a denominator gives a descriptive account of how many people in the observed group were recorded with an event. General statistical interpretation would also consider uncertainty around the underlying event probability. A confidence interval is a range of values compatible with the observed data under a specified statistical model; it is not a guarantee that the true value lies in that range. The registry record does not post confidence intervals or the method used to calculate them. With a small cohort, estimates can be imprecise, and a single participant’s outcome can have a noticeable influence on a descriptive proportion. No new proportion or interval is calculated in this explanation.

Why a control group matters. Randomization is a general method for making treatment groups comparable, on average, with respect to measured and unmeasured factors. This extension has no randomized comparison. Consequently, observed adverse-event counts cannot isolate an intervention effect from differences in illness, prior therapies, selection into the extension, or follow-up. Even a comparison with historical data would require careful attention to differences in eligibility, event definitions, and observation time; the registry record does not report such a comparison.

Exposure and follow-up. The registry states an additional 9 treatments at 3-week intervals and a 12-month primary endpoint timeframe. In general, safety interpretation depends on how much treatment participants actually received and how completely outcomes were observed during follow-up. The record does not report participant-level exposure, missed visits, follow-up completeness, or time to event. It therefore does not support an exposure-adjusted analysis or a detailed account of when events arose. The planned regimen should not be assumed to equal actual exposure for every participant.

Planning calculations are not trial results. Any sample-size illustrations associated with these results are planning exercises based on an observed effect, with stated assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They are not the trial’s own sample-size justification, which is not reported in the registry record. The two-arm planning setup also does not describe this single-group extension design. Such calculations are hypothetical illustrations of sample sizes under assumptions, not observed power and not evidence that the study was designed to detect a particular effect. The registry record does not report a planned effect size, protocol-based power calculation, or analysis plan.

Multiplicity and analysis choices. When a study evaluates multiple outcomes or conducts multiple statistical tests, the chance of at least one apparently unusual result can increase; this is the general issue of multiplicity. The registry lists one outcome measure and no analyses. It does not report whether other outcomes were assessed, whether interim analyses were planned, or whether any multiplicity strategy was specified. Accordingly, no adjustment or planned testing hierarchy can be inferred. A lack of reported analyses also means there is no posted hypothesis test or model to interpret for the primary endpoint.

What can be reproduced. The posted participant counts are descriptive summaries. Recalculations from summary statistics, when available, would be unadjusted and would not replace a sponsor’s own analysis if there were a discrepancy. Here, the record lists no analyses and does not report the primary-endpoint result, so there is no sponsor analysis to compare with a recalculation for that endpoint. The absence of individual-level data also prevents checking event definitions, participant overlap, or the handling of incomplete follow-up.

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("CVA21")
n      <- c(16)
events <- c(16)
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  CVA21  16  16  100.0  79.4  100.0  80.6  100.0  80.5  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no analyses. It does not report a statistical analysis plan, a testing hierarchy, an approach to multiplicity, or whether interim analyses were planned. General statistical practice recognizes that testing multiple outcomes can increase the chance of a chance finding, but the record does not establish how many outcomes were assessed beyond the listed measure or whether any adjustment was used. No specific multiplicity procedure can therefore be attributed to this study.

Missing-data methods are also not reported in the registry record. The record does not describe completeness of the 12-month assessment, handling of participants who discontinued, how events after discontinuation were treated, or whether any participants lacked endpoint assessments. The enrollment and safety denominators do not by themselves answer those questions. In general, incomplete follow-up can affect safety summaries if participants with missing observations differ from those followed throughout the intended period.

The analysis population is not specified beyond the posted CVA21 group and its at-risk counts. The registry does not say whether the primary endpoint was intended to use all enrolled participants, participants who received treatment, or another population definition. It also does not report rules for treatment exposure, protocol deviations, or exclusions. Consequently, the posted safety counts should be interpreted as registry summaries without assuming an undocumented analysis population or missing-data method.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cardiac arrest (6.2%), motor dysfunction (6.2%).

The registry reports 2 participants with serious adverse events among 16 at risk, 13 participants with other adverse events among 16 at risk, and 1 death in the CVA21 group. These are separate posted safety summaries. They do not show the number of event episodes, when events occurred, whether participants appeared in more than one category, or whether investigators judged events related to treatment.

The serious adverse-event terms listed are Cardiac arrest and Motor Dysfunction, each at 6.2%. Those term-specific percentages are registry entries; the record does not provide further event descriptions, timing, severity grades, or causality assessments. They should not be combined or interpreted as evidence of a particular mechanism. The death count is reported separately, and the registry does not say whether the death was considered treatment-related.

Seriousness and the primary endpoint’s Grade 3 or Higher threshold are not interchangeable. The registry does not report the primary-endpoint count, so the serious-event figures cannot fill that gap. With no concurrent control group, these counts describe the study cohort and do not establish comparative safety or causation.

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

The main result that can be read from the registry is descriptive: the CVA21 group had posted counts for serious adverse events, other adverse events, and deaths. The study was an extension for patients previously treated in VLA 007, with a planned additional course of intratumoral CVA21. The registry record does not post a result for the designated primary endpoint, participants with Grade 3 or Higher Adverse Events over 12 months. That missing result limits interpretation of the trial’s stated primary safety question.

The observations do not show what would have happened to comparable participants under a different treatment or without the extension regimen. Because the design has one group and no masking, the posted counts cannot establish a causal effect or quantify a treatment-related increase or decrease in risk. They also do not show that every recorded event was caused by CVA21, or that events not listed did not occur.

The findings apply most directly to the enrolled extension cohort. The registry describes participants as having received 10 earlier doses in VLA 007, but does not report the selection process or full clinical characteristics. The record also does not provide individual exposure, follow-up completeness, event timing, or detailed grading and attribution. These omissions limit both precision and the ability to assess whether the posted summaries capture the full safety experience.

Thus, the record documents safety observations but does not provide a comparative treatment conclusion or a complete analysis of its primary endpoint. A reader should distinguish the available adverse-event counts from unreported details and from causal claims that the design cannot support.

14. Why This Trial Matters Statistically

This study is statistically notable because it asks a safety question in an extension cohort rather than in a conventional randomized comparison. Participants had already received 10 doses in VLA 007, and the extension offered additional CVA21 treatment. That context shapes what the data can represent: outcomes among selected participants entering an extension, rather than a comparison of alternative strategies in a concurrently enrolled population.

The record also illustrates why endpoint definitions matter. The primary outcome is a participant count for Grade 3 or Higher Adverse Events over 12 months, while the posted safety summaries distinguish serious events, other events, and deaths. These summaries answer related but different descriptive questions. Without a posted primary-endpoint result or a definition linking the categories, one cannot substitute one measure for another.

At the same time, a single-group safety record can document events and help describe the experience of the people enrolled. That descriptive role should not be confused with estimating comparative risk or causality. The absence of a control group, the prior-treatment setting, and unreported exposure and follow-up details constrain interpretation. The registry also lists no analyses, leaving the primary safety result and statistical approach unavailable.

For biostatistical interpretation, the key lesson is to separate observed counts, endpoint definitions, and causal comparisons. The record has useful descriptive safety information, but its design and reporting determine which conclusions are supportable. The unreported primary outcome result is especially important because it is the designated endpoint, not merely an ancillary statistic.

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 principal limitation is the absence of a concurrent comparison group. With a single-group design, the posted safety counts cannot distinguish events associated with CVA21 from those related to melanoma, previous treatment, or other causes. The registry also records no masking, and no investigator assessments of event relatedness are reported.

The cohort was an extension for people who had received 10 doses in VLA 007. The record does not report how candidates were selected, how many were considered, or whether entry depended on prior benefit or other criteria. The study population may therefore differ from patients who would enter a new treatment trial. The registry does not report participant characteristics that would help assess representativeness.

The primary endpoint result is not reported in the registry record, despite the outcome being identified as safety over 12 months. The record does not provide severity grades, the endpoint calculation rules, or an explanation of how the posted serious and other adverse-event categories relate to the primary measure. Event timing, duration, resolution, and treatment attribution are also not reported.

Actual exposure and follow-up completeness are unclear. Although the regimen allowed an additional 9 treatments at 3-week intervals, individual treatment receipt, interruptions, and completion are not reported. The registry does not describe missing-data handling, analysis populations, protocol deviations, or planned statistical methods. These gaps limit assessment of event rates over comparable exposure periods and prevent reconstruction of the primary analysis.

Finally, the cohort was small, with 16 participants listed at risk for the safety summaries. The record does not post confidence intervals or other measures of precision. The counts should therefore be understood as observations from this cohort, without assuming that they precisely characterize event frequencies in a broader population.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: CAVATAK in Patients With Stage IIIc or IV Malignant Melanoma to Extend Dosing to 48 Weeks (VLA-008 CALM Ext) — NCT01636882.
• Registry record last updated 2019-07-09; status last verified 2019-06.
• Results first posted 2018-04-23.
• 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

NCT01636882 was a completed Phase 2, single-group extension study of intratumoral CVA21 for patients with stage IIIc or stage IV malignant melanoma who had received 10 doses of CAVATAK in VLA 007. The registry lists enrollment of 16 and an additional regimen of up to 9 treatments at 3-week intervals, at a dose up to 3 × 10⁸ TCID50. The primary safety endpoint was participants with Grade 3 or Higher Adverse Events over 12 months.

The registry reports 2 participants with serious adverse events, 13 with other adverse events, and 1 death among 16 at risk. It lists Cardiac arrest and Motor Dysfunction as serious adverse-event terms, each at 6.2%. The primary-endpoint result, statistical analyses, analysis plan, and missing-data methods are not reported in the registry record. With no control group, the posted counts are descriptive and do not establish comparative risk or causality.