This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Study of Enzalutamide in Patients With Castration-resistant Prostate Cancer (NCT01942837), a na phase 2 study. The primary outcome is Number of Patients With Gene Alterations.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01942837 |
| Phase | Phase 2 |
| Condition | Metastatic Castration-resistant Prostate Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 67 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Dana-Farber Cancer Institute |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned patients with metastatic castration-resistant prostate cancer. The primary endpoint population was narrower: patients who had paired biopsies taken before study treatment and at progression. The registry record does not report how many participants had those paired samples or describe the characteristics of that subgroup.
Intervention
Participants received enzalutamide, listed as 160 mg orally once daily in a 28-day cycle. Treatment was to continue until symptomatic or radiographic progression, or until the participant left the study for another reason. Prior chemotherapy was not required. The trial description says the research examined tumor features before treatment and at progression.
Comparator
There was no comparator arm. The registry classifies the study as single-group, with allocation listed as not applicable and no masking. Consequently, the study does not provide a randomized, concurrent comparison of enzalutamide with another treatment or with no treatment. Changes over time within participants would not, by themselves, provide that comparison.
Primary question
The primary endpoint was the number of patients with gene alterations, among those with paired biopsies. The biopsies were used to investigate possible mechanisms of resistance, including alterations involving AR, tumor suppression genes, DNA repair genes, and SPOP. Whole-exome sequencing was performed on tumor tissue. The registry record does not report the observed count or the specific alteration findings.
3. Trial Design
This was a Phase II study of enzalutamide in metastatic castration-resistant prostate cancer. It is recorded as a single-group study with no masking; allocation is listed as not applicable. These design features matter when interpreting the evidence: the registry record describes treatment and follow-up in one group, not a randomized comparison with a control group. No like-for-like control comparison is available from this study.
The registry lists enrollment as 67 and the study status as completed. The recorded start date is 2013-09-13, and primary completion is listed as 2021-12. The treatment regimen was enzalutamide 160 mg orally once daily, using a 28-day cycle. Treatment was to continue until symptomatic or radiographic progression, or until a participant was taken off the study for another reason. Prior chemotherapy was not a requirement.
The study had a biological focus as well as clinical outcomes. Its primary endpoint counted patients with gene alterations among those with paired tumor biopsies from before treatment and at progression. The progression biopsy could occur up to 41 months after initiation of enzalutamide. The study description identifies alterations in AR, tumor suppression genes, DNA repair genes, and SPOP as areas of interest, and states that whole-exome sequencing was performed on tumor tissue.
The registry also lists 9 secondary outcomes, including serum androgen changes, PSA response and its duration, measurable disease response and its duration, toxicity measurements, biopsy-related analyses, and subsequent lines of therapy. The registry record does not report a detailed statistical analysis plan, the sample-size justification, or the timing or conduct of interim analyses. Those design details should not be inferred from the Phase II label or from the outcome list.
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
| Stage | Enzalutamide |
|---|---|
| STARTED | 67 |
| COMPLETED | 0 |
| NOT COMPLETED | 67 |
Reasons for not completing this period:
| Reason | Enzalutamide |
|---|---|
| Death | 1 |
| Symptomatic or radiographic progression | 49 |
| Adverse Event | 6 |
| Physician Decision | 3 |
| Withdrawal by Subject | 2 |
| Intercurrent Illness | 1 |
| On treatment | 3 |
| Never initiate the treatment | 2 |
Analysis population for the primary outcome, as defined in the registry: Patients who had paired biopsies of pre-study and progression.
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.
Population: Patients who received ≥1 dose of enzalutamide. Two patients didn't initiate the treatment.
| Characteristic | Unit | Enzalutamide |
|---|---|---|
| Participants analysed | 65 | |
| Age, Continuous | years | 70 (66 to 75) |
| Sex/Gender, Customized: Male | Participants | 65 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 4 |
| Race (NIH/OMB): White | Participants | 51 |
| Race (NIH/OMB): More than one race | Participants | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 8 |
| Institution: Dana-Farber Cancer Institute | Participants | 39 |
| Institution: University of Washington | Participants | 19 |
| Institution: Beth Israel Deaconess Medical Center | Participants | 6 |
| Institution: South Shore Hospital | Participants | 1 |
| Prior chemotherapy: Yes | Participants | 16 |
| Prior chemotherapy: No | Participants | 49 |
| Prior docetaxel: Yes | Participants | 15 |
| Prior docetaxel: No | Participants | 50 |
| Prior abiraterone: Yes | Participants | 22 |
| Prior abiraterone: No | Participants | 43 |
| Prior ketoconazole: Yes | Participants | 9 |
| Prior ketoconazole: No | Participants | 56 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Patients With Gene Alterations, measured over Tumor biopsies were performed at pre-study and progression. Progression occurred up to 41 months after initiation of enzalutamide..
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is a count: the number of patients with gene alterations. Its stated population consists of patients who had paired biopsies before study treatment and at progression. The biopsy description identifies a mechanistic purpose: examining tumor changes that might be associated with resistance to enzalutamide. Areas of interest included AR alterations, tumor suppression genes, DNA repair genes, and SPOP; whole-exome sequencing was performed on tumor tissue.
A count can describe how many sampled participants met a specified criterion, but it does not automatically estimate a treatment effect. This endpoint is not framed as a comparison of enzalutamide against a control, nor is it itself a measure of clinical benefit. The registry record does not report the observed count, the denominator of participants with paired biopsies, or results for individual gene alterations. It also does not specify in the record how a participant was classified if several alterations were present, or how incomplete or unusable samples were handled.
General: paired samples can help describe how measured tumor features differ between two time points in the same person. Their interpretation still depends on which participants contributed samples, the quality and timing of the specimens, and the definitions used to classify alterations. Those details are not reported in the registry record, so the endpoint’s biological findings cannot be assessed from the endpoint description alone.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a completed, single-group Phase II study with enrollment of 67. It identifies a primary endpoint focused on gene alterations in participants with paired pre-study and progression biopsies. However, the endpoint’s observed count and the number of participants who contributed paired biopsies are not reported in the registry record. Without those results and the corresponding denominator, the frequency of gene alterations in the sampled population cannot be quantified from this record.
The endpoint has a different role from a conventional clinical response measure. It is intended to characterize tumor features at two stages of treatment, with the study description emphasizing possible mechanisms of resistance. A finding of an alteration in a biopsy would be a molecular observation. By itself, it would not establish that the alteration caused progression, predict an individual participant’s outcome, or show that enzalutamide changed the alteration. Such conclusions would require appropriate analyses and supporting evidence, which are not reported.
The study has no comparator arm and no masking. Thus, any changes observed between pre-study and progression samples would be within-person observations in a selected group, not a randomized contrast. Participants with paired biopsies may differ from those without paired specimens, and the registry record does not report the size or characteristics of either group. Biopsy timing is also relevant: progression occurred up to 41 months after initiation of enzalutamide, so the interval between samples could vary.
The registry lists 9 secondary outcomes, but outcome names alone do not establish what results were observed or how those outcomes were analyzed. The record reports 0 analyses, and the quantitative primary endpoint result is not reported in the registry record. No confidence interval, test result, or adjusted estimate for the gene-alteration endpoint is included in the registry record recorded for this analysis. As a result, precision and statistical uncertainty for that endpoint cannot be evaluated.
The safety summary lists 65 participants at risk for serious adverse events, 8 with serious adverse events, 65 at risk for other adverse events, and 65 affected in the other-adverse-event category; it also lists 41 deaths. These are registry counts, not a comparison against another group. The record does not establish from these figures whether an event was caused by treatment, when each event occurred, or how deaths relate to treatment exposure. The figures should be read descriptively, with those limits in mind.
General: an estimate’s interpretation depends on its definition, analysis population, denominator, and uncertainty. A count without its denominator cannot show a proportion, and a single-group observation cannot isolate treatment effects from other explanations. The available the registry entries support description of the design and recorded counts, but not a conclusion about comparative efficacy or the clinical significance of particular molecular findings.
9. Statistical Methods Explained
The registry identifies the primary endpoint as a count of participants with gene alterations, so the basic outcome type is binary at the participant level: a participant either meets the alteration criterion or does not, according to the study’s classification. The endpoint is then reported as a count. The registry record does not provide the observed count, the number assessed, or the detailed rules used to define an alteration-positive participant. Without those elements, the result cannot be reconstructed or its precision assessed.
What does a count convey?
General: a count states how many observations meet a definition. To understand how common an outcome is in a study population, the count is usually interpreted with its denominator. A count alone does not reveal the proportion of the assessed group, and it does not describe uncertainty around that proportion. No denominator or interval estimate for the primary endpoint is reported in the registry record.
The endpoint population is defined by availability of paired biopsies before study treatment and at progression. This is not necessarily identical to all enrolled participants. A paired-sample analysis requires both time points, so participants without one or both samples are not represented in that endpoint population. The registry record does not report how many participants lacked paired biopsies, why samples were unavailable, or whether missing samples were handled in a particular way. The count therefore cannot be assumed to describe all 67 enrolled participants.
Why do paired samples matter?
General: measuring tumor features in the same participant at two time points can help distinguish within-person changes from differences between people. It does not remove every source of uncertainty. Specimen quality, assay performance, changes in sampling location, the time between specimens, and the definition of a meaningful alteration can affect interpretation. The registry states that biopsies were performed before study treatment and at progression, with progression occurring up to 41 months after enzalutamide initiation. It does not report the distribution of biopsy timing or additional laboratory quality-control details.
The description names AR mutations and amplifications, tumor suppression genes, DNA repair genes, and SPOP as examples of areas assessed. It also states that whole-exome sequencing was performed on tumor tissue biopsies. The registry record does not report a full analytic pipeline, thresholds, handling of multiple alterations in a single participant, or whether all listed alteration types were evaluated with the same criteria. No specific gene-level result should be inferred from the endpoint title or assay description.
What can a single-group design estimate?
General: a single-group study can describe outcomes among participants who received the study treatment, but it cannot create a randomized treatment contrast. When a measurement changes over time, the observed change may reflect treatment, disease course, other care, measurement variation, or factors affecting who has follow-up data. Without a control group, those explanations cannot be separated by a direct randomized comparison. This study is recorded as single-group, with allocation not applicable and no masking.
The registry lists a sample-size planning illustration based on a stated fraction of an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such a two-arm illustration is a planning exercise, not the design actually recorded for this single-group study. It is not observed power and should not be read as evidence that the study had a particular probability of detecting an effect. The registry record does not report the trial’s own sample-size justification. No sample-size calculation or new estimate is needed to interpret the primary endpoint description.
What about statistical uncertainty?
General: a confidence interval expresses a range of values compatible with the data and a specified method, reflecting sampling uncertainty. It does not cover every source of bias or uncertainty, such as missing specimens or selection into the paired-biopsy population. The registry entries do not include a confidence interval for the primary count, or an inferential analysis of the gene-alteration endpoint. The record reports 0 analyses, so no statistical test or adjusted estimate for that endpoint can be described from the available information.
Over-dispersion is a concern for some count models when variability exceeds what the model assumes. It is not a generic correction for every count endpoint, and the registry record does not identify a count model or provide dispersion information. Here, the endpoint is described as a number of participants with gene alterations, not a rate of recurrent events over person-time. It would be inappropriate to infer that an over-dispersed model was used or required.
General: analysis populations should be stated because different inclusion rules can yield different summaries. The registry description identifies the paired-biopsy population for the primary endpoint, but does not report a full analysis-population definition, exclusions, or sensitivity analyses. Those omissions limit assessment of selection and robustness. Similarly, the outcome list does not show whether any endpoint definitions or analytic methods were changed during the study. Such changes are not reported in the registry record.
The posted study details support a description of the design, treatment regimen, biopsy timing framework, and endpoint type. They do not support a numerical estimate of gene-alteration frequency or a treatment-effect estimate. Statistical interpretation should therefore remain focused on what was planned to be counted and on the limits of the unreported result, rather than on assumptions about an analysis method.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 9 secondary outcomes in addition to the primary endpoint. They include several distinct clinical, laboratory, safety, and biopsy-related measures. When a study examines multiple outcomes, the chance of at least one apparently notable finding can increase if many statistical tests are conducted. General: multiplicity methods can control or describe that issue, but the appropriate approach depends on the scientific questions and analysis plan. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or which results were intended to be confirmatory.
The registry record reports 0 analyses. It does not report a detailed statistical analysis plan, interim analyses, or whether any adjustments were made for multiple comparisons. The number of listed outcomes is not itself the number of statistical tests; the actual number and relationship among analyses are not reported. Therefore, neither the extent of multiplicity nor its handling can be evaluated from the outcome list alone.
Missing-data interpretation is especially important for an endpoint requiring paired biopsies. Participants without both a pre-study and progression biopsy cannot contribute a complete pair, but the record does not report the number of such participants, reasons for missing samples, or any imputation or sensitivity method. General: if the availability of a specimen is related to disease status, health, treatment duration, or other participant characteristics, the paired-sample group may differ from the full enrolled group. The direction and magnitude of any such selection cannot be determined.
The primary endpoint population is described as patients who had paired biopsies. The registry does not provide a broader analysis-population definition, participant flow for this endpoint, or rules for handling samples that could not be evaluated. It is therefore not possible to assess whether the reported endpoint, which is itself not numerically reported, represents all enrolled participants or a selected subset. These are limitations of what is reported in the registry record, not evidence that a particular method was or was not used outside the record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Enzalutamide | 8 | 65 | 12.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Enzalutamide | 41 of 65 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Enzalutamide | 65 of 65 |
Most frequent serious adverse event terms
| Event term | Organ system | Enzalutamide |
|---|---|---|
| Gastrointestinal disorders - Other, specify | Gastrointestinal disorders | 2 of 65 |
| Cardiac arrest | Cardiac disorders | 1 of 65 |
| Myocardial infarction | Cardiac disorders | 1 of 65 |
| Colitis | Gastrointestinal disorders | 1 of 65 |
| Diarrhea | Gastrointestinal disorders | 1 of 65 |
| Nausea | Gastrointestinal disorders | 1 of 65 |
| Vomiting | Gastrointestinal disorders | 1 of 65 |
| Lung infection | Infections and infestations | 1 of 65 |
| Sepsis | Infections and infestations | 1 of 65 |
| Urinary tract infection | Infections and infestations | 1 of 65 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Enzalutamide |
|---|---|---|
| Fatigue | General disorders | 34 of 65 |
| Pain | General disorders | 23 of 65 |
| Back pain | Musculoskeletal and connective tissue disorders | 20 of 65 |
| Hot flashes | Vascular disorders | 20 of 65 |
| Hypertension | Vascular disorders | 18 of 65 |
| Diarrhea | Gastrointestinal disorders | 12 of 65 |
| Anemia | Blood and lymphatic system disorders | 11 of 65 |
| Dizziness | Nervous system disorders | 11 of 65 |
| Nausea | Gastrointestinal disorders | 10 of 65 |
| Hypokalemia | Metabolism and nutrition disorders | 10 of 65 |
Serious events with the highest arm-level rate: gastrointestinal disorders - other, specify (3.1%), cardiac arrest (1.5%), myocardial infarction (1.5%), colitis (1.5%), diarrhea (1.5%).
The safety summary lists 65 participants at risk for serious adverse events, with 8 affected. It lists 65 at risk for other adverse events and 65 affected in that category. The registry also records 41 deaths. These are counts in the Enzalutamide group; they are not results from a comparison with a control group. The figures should be read as descriptive registry entries, not as estimates of a treatment effect.
The serious-event terms listed most often include Gastrointestinal disorders - Other, specify at 3.1%, and Cardiac arrest, Myocardial infarction, Colitis, Diarrhea, and Nausea, each at 1.5%. These percentages are quoted as recorded. The summary does not, by itself, establish whether listed terms were judged related to enzalutamide, whether one participant could contribute more than one event, or the timing and duration of the events. Those details are not reported in the registry record.
The count of 41 deaths is not a count of deaths attributed to study treatment. The registry entries do not state the causes, timing, or treatment relationship for those deaths, nor do they provide a comparative mortality analysis. General: adverse-event counts describe events recorded under study definitions; causal attribution requires additional clinical and analytic information. The numbers should not be interpreted as proof that treatment caused or did not cause any listed event.
12. What the Result Does, and Does Not, Mean
This trial addresses a biological question within a clinical study: which gene alterations were present in tumor samples collected before enzalutamide and at progression. Its primary endpoint is a count among participants with paired biopsies. The study description explains that serial biopsies and whole-exome sequencing were used to investigate possible resistance mechanisms. This focus is distinct from testing a randomized difference in clinical outcomes between treatment groups.
The registry record establishes that the study was Phase II, single-group, and completed, with 67 participants enrolled. It also describes enzalutamide administration and lists clinical and laboratory secondary outcomes. It does not report the primary endpoint count, the paired-biopsy denominator, specific molecular findings, or a statistical estimate with uncertainty. Thus, the available record does not show how many participants had gene alterations or how consistently particular alterations were observed.
Even if a molecular difference between pre-study and progression samples were reported, general interpretation would require attention to sample selection, timing, assay methods, and whether the difference was associated with clinical outcomes. A before-and-progression comparison does not alone establish that a particular alteration caused progression or that it predicts response in another person. This record does not provide the analyses needed to support such conclusions.
The single-group design also does not estimate a randomized contrast between enzalutamide and another treatment. The study’s observations cannot, on their own, isolate the effect of enzalutamide from disease changes, other care, or measurement variation. No treatment recommendation follows from the registry entries alone. The safety counts likewise describe recorded events without establishing treatment causation or comparative risk.
In practical statistical terms, the registry gives useful information about the research question, population, treatment, and intended endpoint, but the outcome information needed to judge the endpoint’s size and precision is not reported in the registry record. The distinction between an endpoint being named and its result being available is central: an endpoint description identifies what investigators intended to measure, not what they found.
13. Why This Trial Matters Statistically
Statistically, this study illustrates the difference between a clinical outcome question and a tumor-characterization question. Its primary endpoint counts participants with gene alterations in paired samples, while the listed secondary outcomes include PSA response, measurable disease response, laboratory changes, toxicity, and subsequent therapy. These measures answer different questions and should not be treated as interchangeable evidence.
The paired-biopsy population is particularly important. It is defined by having specimens at both pre-study and progression time points, so it may not include every enrolled participant. The registry record does not report the size or composition of that group. This makes the denominator and the process determining sample availability essential to interpretation, especially when progression can occur up to 41 months after treatment initiation.
The design also demonstrates why a detailed analysis plan matters. With 9 secondary outcomes and several molecular areas named in the study description, readers would need endpoint definitions, planned comparisons, multiplicity handling, and missing-sample procedures to evaluate the strength of individual findings. Those details are not reported in the registry record, which reports 0 analyses. The observed primary endpoint result is also not reported.
Finally, the study’s single-group structure sets a clear boundary on inference. Descriptive findings can characterize participants and their samples, but the design does not provide a randomized treatment comparison. Separating a molecular observation from a causal or predictive claim is essential. The registry entries show what the study set out to examine, while the absence of endpoint results prevents assessment of what the analysis established.
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 principal limitation for interpreting the primary endpoint is that its observed count and denominator are not reported in the registry record. The endpoint applies only to patients with paired pre-study and progression biopsies, but the number of participants meeting that condition is not stated. The record also does not describe how many samples were unavailable, insufficient, or not evaluable, or how such cases were handled.
The study is single-group, with no masking and no randomized comparator. This supports descriptive interpretation but does not provide a controlled estimate of treatment effect. For the biopsy endpoint, within-person comparisons can still be affected by variation in biopsy timing and by which participants contributed paired samples. Progression occurred up to 41 months after initiation of enzalutamide, but the distribution of follow-up intervals is not reported.
The registry description names categories of genetic alterations and says whole-exome sequencing was performed, but it does not provide detailed laboratory or analytic criteria, results by gene, or rules for classifying participants with multiple alterations. A statistical analysis plan, sample-size justification, and interim-analysis details are not reported in the registry record. The registry reports 0 analyses, and no confidence interval or inferential result for the primary endpoint is included in the registry entries.
There are 9 listed secondary outcomes, but the record does not explain how multiplicity was handled or provide numerical results for them in the registry record. The safety summary supplies counts and selected terms, but does not establish event attribution, timing, or comparative risks. These limitations constrain interpretation of both the molecular and safety summaries; they do not establish that unreported procedures or analyses were absent from the conduct of the study.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study of Enzalutamide in Patients With Castration-resistant Prostate Cancer — NCT01942837.
- Registry record last updated 2022-10-24; status last verified 2022-10.
- Results first posted 2022-07-05.
- 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.
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18. Record Summary
NCT01942837 is a completed Phase II, single-group study of enzalutamide in metastatic castration-resistant prostate cancer. Enrollment is listed as 67. The study started on 2013-09-13, with primary completion recorded as 2021-12. Enzalutamide was administered at 160 mg orally once daily in a 28-day cycle, with treatment continuing until symptomatic or radiographic progression or removal from the study for another reason. Prior chemotherapy was not required.
The primary endpoint was the number of patients with gene alterations among patients with paired pre-study and progression biopsies. The study description says whole-exome sequencing was performed, with progression occurring up to 41 months after treatment initiation. The observed endpoint count and paired-biopsy denominator are not reported in the registry record. The record lists 9 secondary outcomes and reports 0 analyses. No comparator arm was used, and no masking was recorded.