Open Label Study of Sipuleucel-T in Metastatic Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Open Label Study of Sipuleucel-T in Metastatic Prostate Cancer (NCT00901342), a na phase 2 study. The primary outcome is Number of Participants Who Received At Least 1 Infusion of Sipuleucel-T in Men With Metastatic Castrate-resistant Prostate Cancer (CRPC).

2. Clinical Question

3. Trial Design

This is a completed, open-label, single-group Phase 2 study of sipuleucel-T in men with metastatic castrate-resistant prostate cancer. The registry record describes it as multicenter. It lists Dendreon as sponsor, an enrollment of 104, and the condition as prostate cancer. The recorded study start is 2009-10, and primary completion is recorded as 2014-12.

The intervention description says participants received sipuleucel-T infusions at 2-week intervals, for a total of 3 infusions. There is no separate control arm in the registry record. Allocation is listed as NA, and masking as NONE. Thus the design does not provide a randomized or blinded within-trial contrast. The posted results should be read as information about participants treated in this study, rather than as a direct estimate of the difference between sipuleucel-T and a comparator.

The registry lists a primary outcome measure focused on the number of participants who received at least 1 infusion. Its timeframe begins at Day 0, described as the first infusion, and extends to up to 3 infusions at 2-week intervals. The outcome population is described as participants who received at least 1 infusion. Although the registry lists enrollment, it does not report the observed primary outcome count or explain how the enrollment figure relates to the outcome population.

The registry record marks the study as completed. A detailed protocol, eligibility criteria, sample-size justification, interim-analysis plan, and full statistical analysis plan are not reported in the registry record. The absence of a comparator and the open-label design are important context for interpreting the study: the design can describe treatment receipt and recorded safety events, but the record does not establish a comparative treatment effect.

4. Participant Flow and Accounting

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

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants who Received At least 1 Infusion

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 Number of Participants Who Received At Least 1 Infusion of Sipuleucel-T in Men With Metastatic Castrate-resistant Prostate Cancer (CRPC), measured over Day 0 (first infusion) and up to 3 infusions at 2-week intervals.

The primary endpoint is the number of participants who received at least 1 infusion of sipuleucel-T in men with metastatic castrate-resistant prostate cancer. The registry defines the population as participants who received at least 1 infusion and gives a timeframe beginning on Day 0, the first infusion, and extending to up to 3 infusions at 2-week intervals.

This endpoint records treatment receipt. It can describe whether participants reached the point of receiving an infusion, but it does not by itself measure whether cancer changed, whether symptoms changed, how long participants lived, or whether treatment performed better than another option. It also does not establish that participants completed all 3 planned infusions; receiving at least 1 infusion is a less restrictive criterion than completing the schedule.

Counting participants who received an infusion can be useful for describing treatment delivery and defining a population exposed to the intervention. However, the count alone needs a clearly reported denominator and outcome result to show how common receipt was among the relevant participants. The registry record does not report the observed primary count, a denominator for that endpoint, or an estimate with uncertainty. It therefore does not support a numerical summary of the primary outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a single-group study with a participant-count primary outcome. In statistical terms, the endpoint asks for a count of participants meeting a defined treatment-receipt condition: receiving at least 1 infusion. The count is not the same thing as a treatment effect. A treatment effect generally requires a comparison, a change over time, or another defined contrast. The record lists no concurrent comparator and reports 0 analyses, so it contains no statistical contrast for the primary outcome.

What would a count describe?

A participant-level outcome can be recorded as whether each participant meets the criterion, then reported as the number meeting it. To interpret that number as a rate or proportion, the relevant denominator must also be specified. The registry gives enrollment as 104, but the primary population is described as participants who received at least 1 infusion. The record does not report the observed primary count or clarify a denominator for the endpoint. It would not be appropriate to turn enrollment into an endpoint denominator without that information.

In general, a confidence interval around a proportion communicates the range of values compatible with the observed data under the chosen statistical model. Its width reflects both the amount of information in the data and the method used to calculate it. That general explanation does not imply that a confidence interval was calculated for this study: none is reported in the registry record. With no posted count, denominator, or analysis, the precision of the primary outcome cannot be assessed.

Why does the study design matter?

A single-group study can describe what was recorded among participants in that group, but it does not create a randomized comparison. Random allocation, when used, can support comparisons by making treatment assignment independent of participant characteristics on average. Here, allocation is listed as NA and the model as SINGLE GROUP. The record therefore does not support a direct estimate of how outcomes would differ under a comparator treatment or control condition.

Masking is listed as NONE, consistent with the open-label description. In general, masking can reduce the influence of knowledge about treatment assignment on some assessments or decisions. Its absence does not automatically invalidate a descriptive count of receipt, but it is relevant when interpreting outcomes that can be influenced by assessment or reporting. The primary measure is receipt of an infusion; the registry does not provide further detail about assessment procedures.

How should the planning assumptions be read?

The sample-size description is explicitly a planning illustration based on an observed effect, not the trial's own design. It specifies a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It also describes the target effect as a stated fraction of the observed effect. These assumptions describe a hypothetical planning framework; they do not convert the study into a two-arm trial or establish that the study was designed with those assumptions.

The description distinguishes time-to-event planning, which gives the total number of events using the Schoenfeld method, from other planning results, which give participants per arm. Those conventions are not results about participants enrolled or observed in this study. The registry record does not report a sample-size justification for the trial itself. Nor does it report the observed primary effect needed to interpret an effect-based planning illustration. Planning sample sizes, even when available, are not observed power and are not evidence that an outcome was or was not statistically significant.

What can the safety summaries establish?

The adverse-event information is presented for the Sipuleucel-T group. It includes counts of participants at risk and affected, a death count, and selected serious adverse event terms with percentages. These are descriptive safety summaries. In general, a count of participants affected is different from a count of event episodes: one participant may have more than one event, while a participant-level affected count records whether an individual experienced an event in the category. The registry record does not give enough detail to reinterpret the posted figures beyond their stated labels.

Comparative safety interpretation would require an appropriate comparator and enough information about event definitions, timing, follow-up, and attribution. Those details and a comparative analysis are not reported in the registry record. The listed event percentages should therefore be read as registry entries, not as evidence that sipuleucel-T caused or prevented any listed event.

What remains unassessed?

The registry record lists 1 outcome measure and 0 analyses. It does not report a statistical model, a confidence interval method, a hypothesis test, or a prespecified analysis population beyond the description of participants who received at least 1 infusion. The protocol and detailed analysis plan are not reported in the registry record. Without those details and without the primary outcome result, readers cannot evaluate model assumptions, missing-data handling, or the prespecification of analyses. The safest statistical reading is descriptive: the record describes the design and some safety figures, but does not report a primary outcome 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("Sipuleucel-T")
n      <- c(98)
events <- c(98)
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  Sipuleucel-T  98  98  100.0  96.3  100.0  96.2  100.0  96.3  100.0

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 1 outcome measure and 0 analyses. It does not report a multiplicity strategy, such as how statistical error would be handled across multiple outcomes or repeated tests. With no reported primary analysis or inferential result, there is no basis for determining whether any adjustment was needed or applied. A broader protocol or statistical analysis plan is not reported in the registry record.

Missing-data handling is not reported in the registry record. The primary outcome population is described as participants who received at least 1 infusion, but the record does not explain how participants without a recorded infusion status were handled, whether any relevant data were missing, or how exclusions were defined. The enrollment figure does not resolve these questions, because the endpoint population is separately defined and its observed count is not reported.

The record also does not report a detailed analysis population such as an intention-to-treat population, nor does it state whether the primary analysis included all enrolled participants or only those who received treatment. The stated outcome population is the only population description attached to the primary measure. A clear account of the population analyzed, missing observations, and any exclusions would be necessary to assess how representative the outcome count is of the enrolled group. Those details are not reported in the registry record.

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: anaemia (2.0%), fatigue (2.0%), decreased appetite (2.0%), myocardial infarction (1.0%), abdominal pain (1.0%).

For the Sipuleucel-T group, the registry lists 98 participants at risk for serious adverse events and 13 affected by serious adverse events. For other adverse events, it lists 98 at risk and 91 affected. The registry also lists 4 deaths. These figures are safety summaries, not estimates from a comparison with another group.

The listed serious adverse event terms and percentages are Anaemia, 2.0%; Fatigue, 2.0%; Decreased appetite, 2.0%; Myocardial infarction, 1.0%; Abdominal pain, 1.0%; and Oral pain, 1.0%. The registry record does not provide further context about event timing, duration, recurrence, severity beyond the serious-event classification, or attribution to treatment. It does not establish that sipuleucel-T caused any listed event.

Counts of affected participants should not automatically be read as counts of all event episodes. The record also does not report a comparative safety analysis or additional follow-up detail needed to assess event rates over time. These entries describe what the registry lists for this group; they do not alone establish a causal safety conclusion.

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

The record establishes that a completed, open-label, single-group Phase 2 study of sipuleucel-T was registered for men with metastatic castrate-resistant prostate cancer. It describes the infusion schedule and identifies receipt of at least 1 infusion as the primary outcome. It also includes safety counts and selected serious adverse event terms. These registry entries help define the study and the kind of outcome it was intended to record.

The record does not report the observed primary outcome count, an endpoint denominator, a confidence interval, a p-value, or a primary analysis. It therefore does not show, numerically, how many participants met the primary outcome or how precisely that count was estimated. Enrollment of 104 is not a substitute for the missing outcome result, particularly because the primary population is described as participants who received at least 1 infusion.

Nor does this single-group design provide a concurrent comparison. The record cannot establish from this endpoint whether sipuleucel-T changed disease outcomes or whether outcomes differed from those under another treatment or control. The primary outcome concerns receiving treatment, not clinical response, survival, or symptom improvement. No such comparative conclusion follows from the posted primary measure.

The safety entries document reported participant counts and percentages in the Sipuleucel-T group. They are useful descriptive information, but the record does not provide the details or comparison needed to attribute events to treatment or to make a comparative safety estimate. Likewise, the planning assumptions described for sample-size illustrations do not constitute trial results, observed power, or proof of an effect.

The appropriate conclusion is bounded: the registry describes the study design, infusion schedule, primary outcome definition, and selected safety summaries, while leaving the primary outcome result and statistical analysis unreported. Any stronger conclusion about clinical benefit, comparative performance, or causation would go beyond what the registry record reports.

14. Why This Trial Matters Statistically

This trial is statistically notable because its primary outcome is treatment receipt rather than a direct measure of clinical status. The endpoint asks whether participants received at least 1 infusion, even though the intervention description specifies a schedule of 3 infusions at 2-week intervals. Those are different questions: initiation of treatment does not establish completion of the schedule or a clinical response.

The study also illustrates why design determines the kinds of conclusions a dataset can support. The registry identifies an open-label, single-group study with allocation listed as NA. That design can describe observations within the treated group, but it does not provide the randomized comparator needed for a direct treatment contrast. Statistical methods cannot recover a missing comparison simply by analyzing the single group more elaborately.

A second important issue is the distinction between enrollment and an endpoint denominator. The registry lists enrollment as 104, but the primary population is participants who received at least 1 infusion. Since the outcome count and denominator are not reported, the primary result cannot be reconstructed from the enrollment entry. This is a useful reminder that a registered enrollment figure and an analyzed outcome population answer different reporting questions.

Finally, the record juxtaposes a primary outcome with no reported analysis and a set of descriptive safety figures. That contrast shows why complete outcome reporting matters: a study description and safety listing do not substitute for a reported primary result, its uncertainty, and a clear account of the analyzed population. The record's planning assumptions also underline the difference between hypothetical sample-size planning and analysis of observed trial data.

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 registry record has important reporting limitations for interpreting this particular study. Most directly, it does not report the observed result for the primary outcome, despite defining that outcome as the number of participants who received at least 1 infusion. It also does not report an endpoint denominator, confidence interval, hypothesis test, or analysis estimate. The enrollment figure alone cannot fill those gaps.

The primary outcome is limited to receipt of an infusion. It does not assess whether participants completed the described schedule of 3 infusions, and it is not a measure of disease response, survival, or symptoms. The registry record does not report these outcomes as part of the primary measure described in this record. A reader should not interpret treatment receipt as evidence of clinical benefit.

The single-group, open-label design has no concurrent comparator, so the record does not support a direct estimate of comparative treatment effects. Allocation is listed as NA and masking as NONE. The record also does not report detailed eligibility criteria, reasons for not receiving an infusion, discontinuations, follow-up completeness, or how missing outcome information was handled. These details would help explain the relationship between enrollment and the stated outcome population.

Safety reporting is also limited in the registry record. It lists participant counts and selected serious adverse event terms with percentages, but does not report event timing, duration, recurrence, attribution, or a comparative analysis. The record does not report a detailed protocol or statistical analysis plan, including any sample-size justification or multiplicity and missing-data procedures. These limitations concern what can be interpreted from the registry record; they do not establish that information was absent from other study documents.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Open Label Study of Sipuleucel-T in Metastatic Prostate Cancer — NCT00901342.
• Registry record last updated 2017-05-23; status last verified 2017-04.
• Results first posted 2017-04-12.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes NCT00901342, an open-label, single-group Phase 2 study of sipuleucel-T in men with metastatic castrate-resistant prostate cancer. It lists Dendreon as sponsor, enrollment of 104, a recorded start of 2009-10, primary completion of 2014-12, and status as completed. The intervention description specifies 3 infusions at 2-week intervals.

The primary outcome is the number of participants who received at least 1 infusion, with the population described as participants who received at least 1 infusion. The observed outcome count and statistical analysis are not reported in the registry record. Safety entries include 13 participants affected by serious adverse events among 98 at risk, 91 affected by other adverse events among 98 at risk, and 4 deaths, along with selected serious adverse event terms and percentages. The single-group, open-label design does not provide a concurrent comparison, and the posted entries do not establish a comparative treatment effect or causation.