Study of Enzalutamide (Formerly MDV3100) as a Neoadjuvant Therapy for Patients Undergoing Prostatectomy for Localized Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Enzalutamide (Formerly MDV3100) as a Neoadjuvant Therapy for Patients Undergoing Prostatectomy for Localized Prostate Cancer (NCT01547299), a randomized phase 2 study. The primary outcome is Pathologic Complete Response Rate.

2. Clinical Question

The trial asked whether the proportion of participants with a pathologic complete response after neoadjuvant treatment differed between enzalutamide alone and a combination of enzalutamide, leuprolide, and dutasteride. Treatment was given before prostatectomy, and the primary outcome was assessed at Day 180.

This question concerns a finding in tissue removed during surgery. It is not a direct measure of long-term disease control, survival, or quality of life. The registry record lists other outcomes, including surgical margins, extracapsular extension, seminal vesicles, lymph nodes, and PSA measures, but does not provide their results in the information summarized for this trial.

3. Trial Design

This was a randomized, open-label, phase 2 study with a parallel-group model. Participants were assigned to one of two treatment groups: enzalutamide alone or enzalutamide combined with leuprolide and dutasteride. The record reports no masking, so the study was not described as blinded. The enrollment listed in the record is 52.

The study concerned neoadjuvant treatment for localized prostate cancer in participants undergoing prostatectomy. The primary outcome was pathologic complete response at Day 180, following 180 days of treatment before surgery. The registry defines that response as an absence of morphologically identifiable carcinoma in the prostatectomy specimen, assessed by both a local and a central pathologist.

The record lists the study as completed. Its start date is 2012-03-31 and its primary completion date is 2013-11-30. These are registry dates; they do not establish when all analyses were completed or when results became available.

The primary-outcome description identifies an intent-to-treat population, with an additional requirement that a prostatectomy sample be evaluated by the local and central pathologist. It also clarifies that the outcome-specific “N” refers to the number evaluable for that measure. The number evaluable and the details of how participants without an evaluable specimen were handled are not reported in the registry record.

The registry record lists 31 outcome measures, including secondary measures on surgical pathology and PSA. It does not report a statistical analysis for the primary endpoint in the record summarized for this trial. In particular, an analysis result, an effect estimate, and a confidence interval for the primary comparison are not reported. The trial’s allocation ratio, randomization procedure, and detailed statistical plan are also 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All participants randomly assigned to study treatment (intent-to-treat population) with a prostatectomy sample evaluated by the local and central pathologist. Here, "N" signifies number of participants evaluable for this specified outcome measure.

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 Pathologic Complete Response Rate, measured over Day 180.

The primary endpoint is the pathologic complete response rate, expressed as a percentage of participants. A participant meets the response definition if the prostatectomy specimen has no morphologically identifiable carcinoma. The record specifies assessment by both the local and central pathologist.

This endpoint uses tissue obtained at prostatectomy to describe whether carcinoma is identifiable in the surgical specimen after neoadjuvant treatment. A percentage expresses the frequency of this defined finding in the outcome population. It is not, by itself, a measure of how long participants remain free of disease or how they fare over longer follow-up.

The timeframe is Day 180, corresponding in the endpoint description to neoadjuvant treatment for 180 days before prostatectomy. The population is described as all participants randomly assigned to study treatment who had a prostatectomy sample evaluated by the local and central pathologist. The record states that the outcome-specific “N” is the number evaluable for this measure.

The endpoint’s definition and assessment are reported, but its result is not. The registry record does not give a response percentage for either treatment group, the number of evaluable participants in either group, or a between-group estimate. It also does not report how disagreements between local and central assessments were handled. Without those results and details, the endpoint cannot support a quantitative interpretation of the treatment comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record describes a randomized, parallel-group comparison with no masking. Random assignment is intended, in general, to make treatment groups comparable on average at the start of a study. It does not guarantee that every measured or unmeasured characteristic will be balanced, especially in a study with a limited enrollment. The allocation ratio and the randomization method are not reported in the registry record, so the details of assignment cannot be assessed.

What does a percentage response measure?

The primary endpoint is a binary outcome at the participant level: the specimen either meets the pathologic complete response definition or it does not. A group percentage describes the frequency of participants meeting that definition among those included in the endpoint denominator. A valid interpretation therefore depends on knowing both the number meeting the definition and the number assessed. The record describes the outcome population and says the outcome-specific “N” is the number evaluable, but it does not give the group-specific denominators or response counts.

The assessment depends on whether carcinoma is morphologically identifiable in the prostatectomy specimen. The local and central pathologist are both named as assessors. The record does not explain how their assessments were combined, whether a disagreement process was used, or which assessment determined the final endpoint classification. Such details can matter when an outcome depends on interpretation of pathology.

How should a confidence interval be understood?

In general, a confidence interval describes the uncertainty around an estimate under a specified statistical procedure. For a treatment comparison, it helps show which effect sizes are reasonably compatible with the observed data and the method used. A narrow interval generally indicates greater precision than a wide interval, while an interval spanning values on both sides of no difference may leave the direction or size of an effect uncertain. These are general interpretations, not findings from this trial.

The primary endpoint lists a 95% confidence interval as its dispersion measure, but no interval or underlying response estimates are reported in the registry record. Therefore, neither the precision of the group percentages nor the uncertainty in a treatment contrast can be evaluated from the posted results. A confidence interval cannot be reconstructed without the relevant event counts and denominators.

What does randomization establish?

Randomization is a design feature, not a substitute for outcome data. In general, it supports a comparison based on assigned groups, provided that the analysis follows an appropriate plan and missing outcomes are handled transparently. The endpoint description refers to all randomly assigned participants, while also requiring an evaluable prostatectomy sample assessed by both pathologists. That qualification means the endpoint denominator may not include everyone assigned. The registry record does not state how many participants lacked an evaluable sample or how such cases were treated in the analysis.

The study is open-label and reports no masking. That describes the design; it does not establish that pathology assessors were or were not masked to assigned treatment. Masking of the pathologists is not reported in the registry record. In general, masking can reduce the possibility that knowledge of assignment influences outcome assessment, especially for outcomes involving judgment. The available record does not permit an assessment of whether this safeguard was used.

What do planning calculations mean?

The sample-size assumptions describe planning illustrations based on a stated fraction of an observed effect. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Such calculations estimate how many participants per arm might be needed under those assumptions to detect a chosen effect size. They are hypothetical planning quantities, not a report of the study’s observed power.

In general, planning calculations depend on the effect size selected, the outcome variability or event frequency, the significance threshold, and the desired power. Choosing a smaller effect to detect generally requires more information than planning to detect a larger one, all else being equal. This is a general statistical principle. The registry record does not report the trial’s original sample-size justification, the effect size anticipated during design, the target power, or whether the design assumptions in the planning illustration were the trial’s own assumptions.

Because the primary outcome results are not reported, a recalculation from observed summary statistics cannot be interpreted for this comparison. A planning illustration should not be mistaken for proof that the trial could or could not detect a clinically important effect. The registry record also does not report interim analyses or a detailed statistical analysis plan.

Why can missing outcomes matter?

When some participants do not have an evaluable endpoint, the analysis can depend on whether their absence is related to treatment assignment, prognosis, surgery, or other factors. In general, excluding participants with missing outcomes can affect the estimated response percentage if those participants differ systematically from those assessed. Imputing outcomes requires assumptions, which should be described and examined. Neither the amount of missing primary-outcome data nor any missing-data method is reported in the registry record.

These general principles explain what would be needed to interpret the endpoint and its uncertainty. They do not establish that any particular method was used in this trial. The record’s endpoint definition is available, but the actual analysis and its results are not reported.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists multiple outcome measures: 31 in total, including the primary pathologic complete response endpoint and secondary surgical pathology and PSA outcomes. Considering several outcomes can create a multiplicity issue. In general, when many statistical tests are conducted, the chance of at least one apparently unusual result can increase unless the analysis plan addresses that possibility. The registry record does not report a multiplicity adjustment, a hierarchy among secondary outcomes, or a detailed statistical plan. It also does not report analyses for these outcomes.

The record identifies the primary-outcome population as all participants randomly assigned to treatment with a prostatectomy sample evaluated by both the local and central pathologist. It says the outcome-specific “N” is the number evaluable. This definition combines random assignment with an evaluability requirement. The number evaluable in each group and the number without an assessable specimen are not reported in the registry record.

Missing-data handling is also not reported. The record does not state whether participants without an evaluable sample were excluded, classified in a particular way, or addressed using an imputation or sensitivity analysis. In general, these choices can influence an estimated response percentage, so the denominator and handling of unavailable outcomes are important to interpretation.

The registry record does not report interim analyses, analysis-population details beyond the endpoint description, or how deviations from assigned treatment were treated. These omissions do not show that the trial used a particular approach; they mean those methods cannot be assessed from the registry record.

11. 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: postoperative ileus (4.0%), clostridial infection (4.0%), lymphocele (4.0%), pelvic abscess (3.7%).

The registry record reports serious adverse events separately from other adverse events. In the enzalutamide plus leuprolide plus dutasteride group, 3 participants among 25 at risk were affected by serious adverse events. In the enzalutamide group, 2 participants among 27 at risk were affected. The record also reports other adverse events affecting 25 participants among 25 at risk in the combination group and 27 among 27 at risk in the enzalutamide group.

These are counts of participants affected within the recorded safety categories, not measures of the primary pathologic outcome. The record lists postoperative ileus, clostridial infection, lymphocele, and pelvic abscess among the serious adverse-event terms, with percentages of 4.0%, 4.0%, 4.0%, and 3.7%, respectively. It does not identify the treatment group or denominator for each listed percentage, so those values should not be assigned to a specific group based on this record.

Deaths are not reported in the registry record. The adverse-event counts alone do not establish comparative safety: interpretation also depends on event definitions, timing, severity, exposure, and the completeness of reporting. Those details are not reported.

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

This trial addresses a focused question about a tissue-based endpoint after neoadjuvant treatment: whether pathologic complete response was observed in participants receiving enzalutamide alone or in those receiving enzalutamide with leuprolide and dutasteride. The record defines the response and specifies assessment by the local and central pathologist.

However, the registry record does not report the primary response rates, evaluable denominators, treatment contrast, or confidence interval. It therefore does not establish whether the groups differed, which group had a higher response rate, or how precisely any difference was estimated. The absence of a reported analysis is not evidence of no effect or of equivalent outcomes.

Even if a pathologic complete response result were available, its scope would be the specified finding in the prostatectomy specimen at the stated assessment time. It would not by itself establish a difference in long-term outcomes. The registry lists additional outcomes, but their results are not reported in the record summarized for this trial. No conclusion about those measures follows from the endpoint definition alone.

The study design provides context for interpreting a reported comparison: randomized assignment, parallel groups, and no masking are recorded. Yet the assignment procedure, analysis plan, missing-data methods, and pathologist masking are not reported. Those details would help readers understand how the outcome comparison was conducted and what risks of bias or uncertainty might remain.

The safety figures describe the recorded participant counts in serious and other adverse-event categories. They do not supply the missing efficacy result and, without further context, should not be treated as a complete comparison of harms. The appropriate reading is therefore limited: the registry describes the trial question, treatment groups, endpoint, and selected safety counts, but does not report the primary outcome analysis needed to answer the central comparison.

13. Why This Trial Matters Statistically

The trial is statistically notable for the gap between a clearly stated primary endpoint and the absence of a reported primary analysis in the registry record. The endpoint is defined in concrete terms: a prostatectomy specimen without morphologically identifiable carcinoma, assessed by the local and central pathologist. Yet without group-specific counts and denominators, readers cannot estimate either response percentage or the treatment contrast.

This distinction is important in clinical research. A protocol question, an outcome definition, and an observed result are different kinds of information. Randomization describes how treatment assignment was intended to occur; it does not reveal the outcomes. Likewise, the existence of a confidence-interval field in the endpoint description does not convey precision when no interval is reported.

The endpoint population also illustrates why denominator reporting matters. The record refers to all randomly assigned participants but requires an evaluable prostatectomy sample assessed by both pathologists. Without the number evaluable in each group and an account of unavailable specimens, it is not possible to determine how the outcome population relates to the randomized population.

The registry lists several secondary measures in addition to the primary endpoint. In general, multiple outcomes call for attention to prespecification and multiplicity, but the statistical plan and any multiplicity approach are not reported. The record therefore gives readers an outline of the questions measured without enough information to evaluate the inferential framework.

Finally, planning calculations and observed results answer different questions. A planning illustration can describe assumptions for a hypothetical future design; it cannot replace the trial’s outcome estimates or be read as observed power. This distinction is especially relevant when the primary comparison itself is not reported.

14. 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 most consequential limitation of the registry record for interpretation is that it does not report the primary endpoint results. No group response rates, outcome denominators, treatment contrast, confidence interval, or p-value are given. The record lists no analyses, so the primary question cannot be answered from the reported information.

The endpoint population is described as randomly assigned participants with a prostatectomy sample evaluated by both the local and central pathologist. The number meeting that evaluability condition is not reported. The record does not describe how samples without an evaluation were handled, whether any participants did not undergo prostatectomy, or how discordant pathology assessments were resolved.

The trial is identified as open-label, but masking of the local or central pathologist is not reported. The registry record also does not report the allocation ratio, randomization method, protocol deviations, treatment adherence, or analysis plan. These omissions limit assessment of the conduct and analysis, rather than demonstrating that any specific problem occurred.

The registry lists secondary outcomes, but their results and any multiplicity strategy are not reported. Safety information includes affected-participant counts and selected serious-event terms, but the treatment-group attribution and denominators for the listed term percentages are not provided. Deaths are not reported in the registry record.

The record’s endpoint is a pathology finding at surgery. It does not, on its own, describe longer-term outcomes. The listed dates and completed status do not supply follow-up results or establish the completeness of outcome reporting.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Enzalutamide (Formerly MDV3100) as a Neoadjuvant Therapy for Patients Undergoing Prostatectomy for Localized Prostate Cancer — NCT01547299.
• Registry record last updated 2018-10-23; status last verified 2018-10.
• Results first posted 2015-04-10.
• 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.

18. Record Summary

The registry record describes a completed, randomized, open-label, parallel-group phase 2 study of neoadjuvant treatment for localized prostate cancer before prostatectomy. The enrollment listed is 52. The comparison was enzalutamide alone versus enzalutamide with leuprolide and dutasteride.

The primary endpoint was pathologic complete response at Day 180, defined as no morphologically identifiable carcinoma in the prostatectomy specimen, assessed by the local and central pathologist. The endpoint population is described as randomly assigned participants with an evaluable specimen.

The record does not report the primary outcome results or analyses. It lists secondary pathology and PSA outcomes, as well as selected adverse-event counts. Details of the statistical plan, missing-data handling, and outcome denominators are not reported in the registry record.