PTC299 in Treating Patients With HIV-Related Kaposi Sarcoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PTC299 in Treating Patients With HIV-Related Kaposi Sarcoma (NCT00686842), a na phase 1, phase 2 study. The primary outcome is Safety and Toxicity of Anti-VEGF Small Molecule PTC299.

2. Clinical Question

3. Trial Design

This was a phase I/II, single-group study of PTC299 in patients with HIV-related Kaposi sarcoma. The registry describes one arm, “VEGF Inhibitor PTC299,” and states that all subjects received PTC299. Enrollment was 17. Allocation is listed as not applicable and masking as none. Thus, the design was not a randomized comparison, and the study had no concurrent control arm for estimating how outcomes would have differed under another treatment or no study treatment.

The registry lists the study status as terminated. The recorded start is 2008-09, and primary completion is recorded as 2010-11. These dates describe the registry timeline; the information available does not state why the study was terminated or whether termination followed a planned stopping rule. A reason for termination is not reported in the registry record.

The trial’s stated purpose included studying side effects and the best dose of PTC299, as well as assessing how it worked in this population. The registry record lists safety and toxicity as the primary outcome, with pharmacokinetics and several laboratory and tumor-biopsy measures among secondary outcomes. The listed secondary measures include serum and plasma VEGF, VEGFR, and cytokine profiles; HIV and KSHV viral loads; T-lymphocyte subsets; and tumor expression and proliferation measures. The record does not provide a detailed dose-escalation scheme or identify a selected dose, so neither can be reconstructed from the available information.

The registry lists 9 outcome measures and 0 analyses. A detailed statistical analysis plan, analysis populations, and the handling of repeated measurements are not reported in the registry record. Because the study was single-group, its design can describe outcomes observed among participants who received PTC299, but it cannot provide a randomized estimate of comparative benefit or harm.

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 Toxicity of Anti-VEGF Small Molecule PTC299, measured over All study visits.

The primary outcome is described as safety and toxicity of PTC299, measured as the number of participants who experienced an adverse event of grade 3 or greater. Its unit is participants, and the stated timeframe is all study visits. This is a participant-level count: it concerns whether participants experienced an event meeting the stated severity threshold, rather than the total number of event episodes. The record does not clarify how repeated events in one participant were handled for this outcome.

In general, recording the number of participants with more severe adverse events can help describe the frequency of clinically important safety events during follow-up. It is distinct from counting every event, because one person may experience multiple events. Severity grade and seriousness are also distinct concepts: a grade threshold describes severity, while a serious adverse event is categorized under seriousness criteria. One category should not be treated as a direct substitute for the other.

The registry’s adverse-event summary separately reports serious and other adverse events. Those counts should not automatically be read as the primary endpoint result, because the summary categories are not explicitly identified as the grade 3-or-greater endpoint. A result explicitly linked to that primary definition, including any analysis method or uncertainty estimate, is not reported in the registry record. Accordingly, the adverse-event summary can be described as recorded, but it does not establish a complete estimate for the primary endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on matching each number to its outcome definition, unit, and design. In this trial, the primary outcome is described as a count of participants who experienced an adverse event of grade 3 or greater during all study visits. The unit is participants, not event episodes. A participant-level count answers how many participants had at least one qualifying event; an event-level count would instead count each episode and could count one participant more than once. The registry does not explain how repeated qualifying events were handled beyond the participant-level wording.

What does a participant count describe?

A participant count is a descriptive summary of the enrolled group. It is not, on its own, a measure of causal effect. To estimate a contrast between treatments, a study generally needs a suitable comparator and a defined comparison method. General explanation: random allocation can help balance prognostic factors across groups, while a concurrent control also helps account for changes that occur over time independently of treatment. This study is listed as single-group, with allocation not applicable and no masking. It therefore does not offer a randomized between-group contrast.

The adverse-event summary separates serious adverse events from other adverse events. These labels describe different aspects of adverse-event reporting. General explanation: seriousness is a classification based on regulatory criteria, while severity grading describes how intense an event is. A serious event is not necessarily identical to an event meeting a particular severity grade, and the grade 3-or-greater primary endpoint should not be inferred directly from a serious-event count. The registry’s summary does not explicitly map its serious and other categories onto the grade-based primary outcome.

What does uncertainty quantify?

A confidence interval is a statistical range constructed by a specified method to express uncertainty around an estimate. General explanation: its width depends on the amount of information, the observed data, and the chosen method. An interval does not remove design limitations, and it cannot make an uncontrolled comparison causal. The registry record reports no confidence interval for the primary outcome or the adverse-event counts. Consequently, the precision of those estimates cannot be described using an interval from the record.

A hypothesis test evaluates data against a specified null hypothesis under stated assumptions. A p-value is meaningful only in relation to that question, the model, and the analysis plan. The registry record lists 0 analyses and does not report a hypothesis test, p-value, or adjusted estimate. It would be inappropriate to infer statistical significance or lack of significance from the counts alone. Nor does a lack of reported testing show that an effect is absent.

How should multiple outcomes be considered?

The record lists 9 outcome measures. They address safety, pharmacokinetics, viral measures, immune-cell subsets, circulating biomarkers, and tumor-biopsy measures. When several outcomes are examined, general statistical practice considers whether the questions are confirmatory or exploratory and whether the analysis accounts for multiple opportunities to identify a chance finding. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or which outcomes were analyzed. The number of listed outcomes alone does not establish that any particular adjustment was made.

The record also does not report an analysis population, such as whether analyses included all enrolled participants or only participants with particular follow-up measurements. General explanation: the analysis population defines which participants contribute to an estimate, and different choices can affect interpretation. Missing outcome data can also affect a participant-level count if the outcome status is unknown for some participants. The record does not describe missing-data handling, exclusions, or completeness of follow-up, so these features cannot be assessed.

What is the role of the planning illustration?

The sample-size assumptions describe a planning illustration computed from the observed effect, not the trial’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event calculations, the illustration gives the total number of events; other calculations are expressed as participants per arm for 80% power or another stated power level. These are planning concepts, not observed trial outcomes or observed power.

The hypothetical equal-allocation comparison in that illustration is different from this trial’s single-group design, in which all subjects received PTC299. The planning assumptions do not show that the trial enrolled a comparator group or followed that design. They also do not establish that the original trial was planned using those assumptions. A sample-size illustration cannot replace a trial-specific protocol or statistical analysis plan, neither of which is reported in the registry record.

General explanation: over-dispersion matters when variation in count data exceeds what a model’s assumed distribution allows. If a count model assumes less variability than the data contain, estimated uncertainty can be too small. No count-model analysis or dispersion estimate is reported in this registry record, and the primary outcome is described as a participant count rather than a reported event-rate model. Over-dispersion should therefore be understood as a general modeling issue, not as a documented feature of this trial’s analysis.

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("VEGF Inhibitor PTC299")
n      <- c(17)
events <- c(7)
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  VEGF Inhibitor PTC299  17  7  41.2  18.4  67.1  21.6  64.0  21.5  64.3

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 9 outcome measures, including the primary safety and toxicity outcome and secondary pharmacokinetic, viral, immune, biomarker, and biopsy outcomes. It does not report a statistical plan for controlling multiplicity, a hierarchy among outcomes, or which secondary outcomes were analyzed. With multiple outcomes, general statistical practice distinguishes a prespecified primary question from exploratory questions and considers the increased chance of chance findings across repeated tests. The available record does not establish how that issue was handled in this study.

The record lists 0 analyses and does not provide inferential estimates, confidence intervals, hypothesis tests, or p-values. It also does not report an analysis population, such as an intention-to-treat or evaluable-participant set. Those labels should not be assigned based on the single-group description alone. The record does not state whether every enrolled participant contributed data to each outcome or whether participants were excluded from particular analyses.

Missing-data methods and outcome completeness are not reported in the registry record. General explanation: when outcome status is unknown, the treatment of those observations can affect a participant-level estimate, especially if missingness is related to health status or adverse events. The stated timeframe covers all study visits, but the record does not say whether all participants completed all visits or how incomplete follow-up was handled. No imputation, sensitivity analysis, or other missing-data procedure can be inferred.

The record also does not describe interim analyses, stopping boundaries, or a statistical reason for termination. The listed terminated status alone does not show why the study ended or whether any planned analysis was changed.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: sudden death (5.9%), renal and urinary disorder (5.9%), myalgia (5.9%).

The adverse-event summary lists 3 participants affected by serious adverse events among 17 at risk. It separately lists 17 participants affected by other adverse events among 17 at risk. These are participant counts in the registry’s adverse-event reporting; they are not necessarily counts of event episodes. A participant may experience more than one event, and the record does not say whether participants in the serious and other categories overlap.

The top serious-event terms are “Sudden death,” “Renal and urinary disorder,” and “Myalgia,” each reported as 5.9%. These are entries in the serious-event summary. The record does not report a separate death count, so the listed term should not be treated as a death total. Nor does the record establish whether each term occurred in a different participant.

Seriousness and severity grade are different classifications. The primary outcome is described using a grade 3-or-greater threshold, while the safety summary separates serious and other events. The available information does not explicitly connect those categories to the primary endpoint definition. It is therefore important not to interpret the serious-event count as the grade 3-or-greater primary outcome.

These counts describe the study group and do not provide a comparison against another treatment. The record does not report an uncertainty interval or an adjusted analysis for these figures.

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

The posted results describe adverse events recorded among participants in a single-group study of PTC299 for HIV-related Kaposi sarcoma. The registry’s safety summary reports 3 participants affected by serious adverse events and 17 affected by other adverse events, with 17 at risk in each category. It also lists three top serious-event terms, each with a reported value of 5.9%. These are descriptive registry entries, not comparative estimates.

The primary outcome is defined as the number of participants with an adverse event of grade 3 or greater during all study visits. The serious-versus-other categories in the adverse-event summary do not explicitly establish the result for that grade-based endpoint. A grade 3-or-greater endpoint count is not reported in a way that can be distinguished from the separate adverse-event summaries. The record also provides no confidence interval or inferential analysis for the primary outcome.

These findings do not establish whether PTC299 causes more or fewer adverse events than another treatment, because the study had no concurrent control group. They also do not establish whether the treatment improves tumor outcomes or other clinical outcomes. Although the registry lists secondary measures involving viral load, immune-cell subsets, biomarkers, and tumor biopsies, outcome results for those measures are not reported in the information available for this analysis.

The record’s terminated status does not by itself explain why the study ended, whether all planned follow-up occurred, or whether the termination was related to safety or efficacy. Those reasons are not reported in the registry record. The absence of a reported result should not be treated as evidence that an outcome did not occur or that an effect was absent.

General interpretation: an uncontrolled study can document what was observed among participants who received an intervention, but it cannot by itself distinguish treatment effects from other explanations for those observations. The counts should therefore be read as a record of reported events in this study, not as a definitive estimate of risk in other patients or as evidence of comparative treatment effect.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the difference between describing outcomes and estimating comparative effects. The registry describes a single group in which all subjects received PTC299. That design can record participant-level safety events and measurements over time, but it has no concurrent control group to show what would have happened under an alternative condition.

The distinction between the stated primary endpoint and the adverse-event summary is also important. The primary outcome concerns participants with an adverse event of grade 3 or greater. The registry separately reports serious and other adverse events. Because seriousness and severity grading are not interchangeable, readers need an explicit outcome definition and result mapping before treating a summary count as the primary endpoint estimate.

The study also lists a broad set of secondary measures spanning pharmacokinetics, viral loads, immune subsets, circulating biomarkers, and tumor tissue. Such measures can describe different biological and clinical dimensions, but their presence in a registry does not show that results were analyzed or reported. A statistical interpretation depends on the results, analysis methods, and handling of multiple questions, none of which are detailed in the registry record.

Finally, the registry reports no analysis entries, confidence intervals, or hypothesis tests. This limits what can be said about precision and uncertainty. The record remains useful for identifying the study’s design, stated outcome, and recorded adverse-event counts, while also making clear that a descriptive safety summary is not a randomized comparison and does not establish a causal 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.

The study is single-group, and all subjects received PTC299. There is no concurrent control arm, so observed outcomes cannot be contrasted with outcomes under another treatment or no study treatment. Allocation is listed as not applicable and masking as none. The record therefore does not support a randomized comparative estimate.

Enrollment was 17. The registry record does not provide a detailed account of participant characteristics, eligibility criteria, prior therapy, or disease status beyond HIV-related Kaposi sarcoma. Without those details, it is difficult to assess how closely the study group represents any broader clinical population.

The registry’s primary outcome is defined as participants experiencing an adverse event of grade 3 or greater, but the adverse-event summary reports serious and other categories without explicitly mapping them to that endpoint. Seriousness and severity grade are different classifications. A primary endpoint result under the stated definition is therefore not reported in a clearly identifiable way. The separate death count is also not reported in the registry record.

The record lists 9 outcome measures but does not report results for the listed secondary outcomes in the information available for this analysis. It also reports 0 analyses, with no confidence intervals, hypothesis tests, or adjusted estimates. A statistical analysis plan, multiplicity procedure, analysis population, and missing-data methods are not reported in the registry record.

The study is listed as terminated, but the reason is not reported. The record does not explain whether follow-up was complete, how many participants completed all visits, or whether the termination affected planned outcome collection. These gaps limit interpretation of the duration and completeness of safety observation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: PTC299 in Treating Patients With HIV-Related Kaposi Sarcoma — NCT00686842.
• Registry record last updated 2018-06-06; status last verified 2018-05.
• Results first posted 2012-03-05.
• 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 record describes a phase I/II, single-group study of PTC299 in patients with HIV-related Kaposi sarcoma. Enrollment was 17, all subjects received PTC299, allocation was not applicable, and masking was none. The study is listed as terminated.

The primary outcome concerns the number of participants who experienced an adverse event of grade 3 or greater during all study visits. The adverse-event summary reports serious and other event categories separately, but does not explicitly identify either as the grade-based primary endpoint result. It lists 3 participants affected by serious adverse events and 17 affected by other adverse events, with 17 at risk in each category.

The record lists 9 outcome measures and 0 analyses. It does not report inferential estimates, analysis populations, missing-data methods, or results for the listed secondary measures. The single-group design supports descriptive reporting of observed events, not a randomized comparison or a causal estimate of treatment effect.