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 Orteronel in Treating Patients With Metastatic Hormone-Resistant Prostate Cancer (NCT01866423), a na phase 2 study. The primary outcome is Androgen Receptor (AR) Protein Expression Levels in CTCs.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01866423 |
| Phase | Phase 2 |
| Condition | Adenocarcinoma of the Prostate, Hormone-resistant Prostate Cancer, Recurrent Prostate Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 4 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Southern California |
| Results posted | Yes |
2. Clinical Question
Population
Patients with metastatic castration-resistant prostate cancer. The registry lists prostate adenocarcinoma, hormone-resistant, recurrent, and stage IV prostate cancer among the conditions. Only 4 patients were accrued.
Intervention
Orteronel without prednisone. The treatment description specifies orteronel 300 mg PO BID on days 1-28, with courses repeating every 28 days in the absence of disease progression or unacceptable toxicity. Laboratory biomarker analysis is also listed as an intervention.
Comparator
There is no separate comparator group in this single-group trial. Allocation is listed as NA, and masking is listed as none. The registry record does not describe a randomized or concurrent control comparison.
Primary question
The primary endpoint concerns androgen receptor protein expression levels in CTCs, with a timeframe of up to 4 weeks. The registry describes a planned analysis of expression and response, but reports that no data analysis was performed. It therefore does not report whether expression was associated with response.
3. Trial Design
This is a phase 2, single-group trial of orteronel without prednisone in patients with metastatic castration-resistant prostate cancer. The sponsor is the University of Southern California. The registry lists the study start as 2013-10-25 and the primary completion date as 2015-07-23; its status is terminated. These record details do not establish why the study ended.
The treatment description specifies orteronel 300 mg PO BID on days 1-28, with courses repeating every 28 days if disease progression or unacceptable toxicity has not occurred. Laboratory biomarker analysis is also listed. Allocation is NA, masking is none, and the model is single group. Thus, the record does not describe a randomized comparison or a concurrent control arm. Any changes over time in participants would not, by themselves, distinguish treatment effects from other explanations.
The registry lists enrollment of 4 and states that only 4 patients were accrued. It does not report a sample-size justification or explain whether the enrollment target changed. The listed secondary outcomes include best PSA response, absolute change in PSA, response rate and duration using RECIST Version 1.1 and PCWG2 criteria, and grade 3 or higher toxicity. Seven outcome measures are listed overall, but the registry reports zero analyses. The record therefore describes intended outcomes and treatment procedures, not completed estimates for those outcomes.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: The trial had no pre-assignment criteria. All subjects were given the same treatment.
Overall Study
| Stage | Treatment (Orteronel) |
|---|---|
| STARTED | 4 |
| COMPLETED | 0 |
| NOT COMPLETED | 4 |
Reasons for not completing this period:
| Reason | Treatment (Orteronel) |
|---|---|
| Lack of Efficacy | 3 |
| Sponsor Decision | 1 |
Analysis population for the primary outcome, as defined in the registry: Only 4 patients were accrued to this trial. No data analysis was performed.
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.
| Characteristic | Unit | Treatment (Orteronel) |
|---|---|---|
| Participants analysed | 4 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 |
| Age, Categorical: >=65 years | Participants | 3 |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 4 |
| Region of Enrollment: United States | Participants | 4 |
6. Primary Endpoint
The registry lists the primary outcome as Androgen Receptor (AR) Protein Expression Levels in CTCs, measured over Up to 4 weeks.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is androgen receptor (AR) protein expression levels in CTCs, with measurement described over a timeframe of up to 4 weeks. It is a biomarker endpoint rather than a direct clinical outcome such as tumor response or survival. In general, measuring a biomarker can help characterize tumor biology and may help investigate whether a biological feature is associated with a clinical response.
The registry describes a two-sample t-test and says that, once an association between AR expression and response is established, graphical methods such as receiver-operator curves (ROC) or a more quantitative maximal chi-square method could be used to examine a possible cut-point. Such a cut-point would divide expression values into groups that differ in their likelihood of PSA response. This is a description of intended methods, not evidence that an association or useful threshold was found.
The record states that only 4 patients were accrued and that no data analysis was performed. It gives no endpoint values, group summaries, test statistic, confidence interval, or p-value. The primary endpoint therefore has no reported numerical result in the registry record. The intended measurement and analysis should not be mistaken for an observed finding.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the registry record reports no analysis of the primary endpoint. Although the endpoint is defined as AR protein expression levels in CTCs and the timeframe is up to 4 weeks, no expression data or association estimate is reported. There is consequently no reported estimate of the relationship between this biomarker and response, and no precision measure with which to judge uncertainty.
Only 4 patients were accrued. That enrollment is relevant to how much information the trial could contribute, but enrollment alone does not reveal the distribution of biomarker values, the number of responses, or the size of any association. Because no data analysis was performed, the record does not support an inference about the direction or magnitude of a biomarker-response relationship. It also does not report treatment response estimates for the listed secondary outcomes.
The design is single group, with no masking and allocation listed as NA. A single-group study can describe outcomes among participants, but it cannot make a like-for-like comparison with a separate control arm that is not present. Changes observed during treatment could have more than one explanation; the design does not isolate the effect of orteronel from all other influences. In this case, even descriptive outcome analyses are not reported in the registry record.
The planned primary analysis includes a two-sample t-test, but the registry does not explain what two samples would be compared. The single-group design does not identify a separate treatment arm, and no analysis was performed. This leaves the operational comparison unclear; it is not a basis for assuming which participants or measurements would have formed the two samples.
The record lists several secondary outcome topics, including PSA response, RECIST Version 1.1 and PCWG2 response measures, and grade 3 or higher toxicity. Those entries describe outcomes of interest rather than results. The adverse-event information is a limited exception in that counts and listed serious-event terms appear in the registry, but those figures do not substitute for an efficacy analysis or resolve the unanswered primary endpoint question.
Overall, the posted information characterizes a small, terminated, single-group trial and its intended biomarker question. It does not establish whether orteronel changed AR expression, whether AR expression was associated with response, or how the treatment performed on the listed clinical outcomes. The absence of an analysis is not evidence of no association or no response; it means the registry record supplies no analyzed estimate to assess.
9. Statistical Methods Explained
The registry describes the primary endpoint as AR protein expression levels in CTCs and names a two-sample t-test. In general, a two-sample t-test compares the mean values of a continuous measure between two groups. Its interpretation depends on defining the groups, obtaining measurements, and having data suitable for the comparison. The registry does not identify the two samples or groups, and the single-group design does not list a separate comparator arm. No data analysis was performed, so there is no reported test result to interpret.
What would the t-test address?
In general, a t-test addresses evidence about a difference in group means under its statistical assumptions. It does not, by itself, establish that a biomarker causes a clinical response or that a finding will predict response in other patients. The registry’s endpoint description refers to the association between AR protein expression and response, but does not give a completed comparison, an estimate, or a measure of uncertainty. The test name alone is not an outcome.
What do the ROC and maximal chi-square methods add?
The record says that ROC methods or a maximal chi-square method might be considered once an association between AR expression and response is established. In general, ROC methods examine how well a continuous marker separates people with different outcome classifications across possible thresholds. A cut-point is a value used to divide measurements into categories. A maximal chi-square approach searches across candidate cut-points for one that separates outcomes strongly according to a chosen statistic.
Searching across thresholds can make a selected cut-point appear more informative than it would be in new data. General statistical practice therefore treats such a threshold as exploratory unless it is tested independently or otherwise validated. This issue is especially important when the information base is small. The registry does not report a selected threshold, sensitivity, specificity, validation, or any completed threshold analysis. These are general cautions about the named methods, not findings from this trial.
What do the outcome entries mean?
The secondary outcomes cover PSA response and change, response rate and duration according to RECIST Version 1.1 and PCWG2 criteria, and grade 3 or higher toxicity. In general, an outcome definition specifies what is measured and how observations are classified. It does not show that the outcome was measured, analyzed, or favorable. The registry lists seven outcome measures and zero analyses; it reports no treatment-effect estimates for the listed efficacy outcomes.
For a treatment-effect comparison, a control group can help distinguish the treatment contrast from changes that might occur over time or for other reasons. This trial is listed as single group, with allocation NA and no masking. The registry does not describe a control arm or randomized allocation. Thus, the design does not offer a randomized between-arm estimate. No adjusted or unadjusted analysis results are reported.
How should planning calculations be read?
Sample-size calculations based on an observed effect are planning illustrations, not evidence that the trial had a particular probability of detecting a result. In general, such calculations depend on assumptions about the target effect, significance level, allocation, and statistical model. The registry describes illustrations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect defined as a stated fraction of the observed effect. It distinguishes participants per arm for non-time-to-event outcomes from total events for time-to-event outcomes.
Those assumptions describe hypothetical planning, not this trial’s single-group enrollment or its own design justification. The registry does not report a trial-specific sample-size justification. Moreover, it reports no analysis from which an observed effect for the illustrations could be evaluated. Any resulting planning quantity is not observed power, does not alter the fact that 4 patients were accrued, and does not supply missing endpoint results.
General statistical interpretation also depends on data quality, missing observations, analysis populations, and the prespecified analysis plan. The registry record does not report those details for this endpoint. Without outcome values and a defined comparison, neither a test of statistical significance nor an assessment of precision can be reconstructed from the record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary biomarker endpoint and several secondary outcome topics, but does not report a multiplicity strategy. In general, testing multiple endpoints or multiple possible cut-points can increase the chance of findings that appear compelling by chance. A prespecified hierarchy, adjustment, or clearly exploratory interpretation can help readers understand how multiple analyses are handled. No such approach is reported in the registry record.
The primary endpoint description mentions a two-sample t-test, followed conditionally by ROC or maximal chi-square methods if an association is established. The record does not say whether these analyses were prespecified in a protocol, how the conditional sequence would be handled statistically, or whether any adjustment for examining multiple cut-points was planned. No analysis was performed, so the record provides no basis for evaluating how multiplicity was handled in practice.
Missing-data procedures are not reported in the registry record. The record does not state whether endpoint measurements were missing, how missing observations would be treated, or whether sensitivity analyses were planned. Analysis populations, including any rules for inclusion in the primary analysis, are also not reported. With only 4 patients accrued and no data analysis reported, the registry does not establish how many participants had usable endpoint measurements.
These omissions limit assessment of the intended statistical analysis, but they do not establish that data were missing or that a particular method was used. The registry reports no analysis and does not provide the detail needed to assess analysis populations, multiplicity, or missing-data handling.
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 |
|---|---|---|---|
| Treatment (Orteronel) | 1 | 4 | 25.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Treatment (Orteronel) | 0 of 4 |
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 |
|---|---|
| Treatment (Orteronel) | 3 of 4 |
Most frequent serious adverse event terms
| Event term | Organ system | Treatment (Orteronel) |
|---|---|---|
| Abdominal Pain | Gastrointestinal disorders | 1 of 4 |
| Anemia | Blood and lymphatic system disorders | 1 of 4 |
| Hypertension | Vascular disorders | 1 of 4 |
| Platelet count decreased | Investigations | 1 of 4 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Treatment (Orteronel) |
|---|---|---|
| Anorexia | Metabolism and nutrition disorders | 3 of 4 |
| Cough | Respiratory, thoracic and mediastinal disorders | 3 of 4 |
| Fatigue | General disorders | 3 of 4 |
| Nausea | Gastrointestinal disorders | 3 of 4 |
| Abodminal Pain | Gastrointestinal disorders | 2 of 4 |
| Aspartate Aminotransferase increased | Investigations | 2 of 4 |
| Back pain | Musculoskeletal and connective tissue disorders | 2 of 4 |
| Constipation | Gastrointestinal disorders | 2 of 4 |
| Fever | General disorders | 2 of 4 |
| Hyperglycemia | Metabolism and nutrition disorders | 2 of 4 |
Serious events with the highest arm-level rate: abdominal pain (25.0%), anemia (25.0%), hypertension (25.0%), platelet count decreased (25.0%).
The registry lists a treatment group with 4 participants at risk for serious adverse events and 1 affected. For other adverse events, it lists 4 at risk and 3 affected. The death count is 0. These are counts in the registry record; they do not, on their own, describe event timing, duration, recurrence, or the number of events per participant.
The registry lists abdominal pain, anemia, hypertension, and platelet count decreased among the serious adverse event terms, each at 25.0%. Those percentages should be read as the registry’s reported values. The record does not provide further detail about severity beyond the serious-event classification, clinical course, or whether participants had more than one listed event.
Adverse-event counts describe what was recorded among participants in this trial. With a single group and 4 participants, these figures do not provide a comparison with an untreated or alternative-treatment group. They also do not establish how frequently similar events would occur in a larger population. The serious-event figures and listed terms are safety observations, not an efficacy result.
12. What the Result Does, and Does Not, Mean
The registry record documents a phase 2 study of orteronel without prednisone in metastatic castration-resistant prostate cancer. It records a single-group design, enrollment of 4, and termination. It also identifies AR protein expression levels in CTCs as the primary endpoint, with a timeframe of up to 4 weeks. These details define the scope of the question and the limited size of the accrued group.
The record does not report an analysis of the primary endpoint. It therefore does not show whether AR expression changed, whether it was associated with PSA response, or whether any cut-point could separate participants by response. It also provides no analyzed estimates for the secondary response outcomes. This absence should not be interpreted as evidence that the biomarker has no relationship with response or that treatment had no effect; the relevant analyses are not reported.
The design also limits what could be concluded even if descriptive outcomes had been analyzed. A single-group study without a separate control arm cannot provide a randomized treatment comparison. Outcomes among participants would not by themselves isolate the effect of orteronel from other explanations. The registry does not report a randomized allocation, masking, or a control group.
The posted safety counts provide limited descriptive information: the record lists serious and other adverse events, deaths, and serious-event terms. These observations are not a comparative safety analysis, and their small participant base limits how much they can characterize events outside this trial.
Accordingly, the record supports a description of the trial’s design, intended measures, accrued enrollment, and listed safety observations. It does not support a numerical conclusion about the primary biomarker question or comparative conclusions about treatment response. The distinction is between a study question and an analyzed answer: the registry records the former, but not the latter.
13. Why This Trial Matters Statistically
This trial is statistically notable for the gap between an explicitly described biomarker analysis and the absence of reported analysis. The endpoint description names a two-sample t-test and possible follow-up methods for exploring a cut-point, yet the registry states that no data analysis was performed. Readers should distinguish this planned analytical language from results: a named method does not mean it was carried out or produced a finding.
The single-group design is also important. The registry lists no randomized allocation and no masking, and there is no separate comparator group. This means the trial cannot yield a randomized between-group estimate. Even complete descriptive data would answer a different question from a controlled comparison.
Enrollment of 4 further constrains the information represented by the study. The registry’s sample-size illustrations are planning exercises based on an observed effect, not observed power or a justification for this study’s enrollment. The record does not give the trial’s own sample-size rationale, and it reports no analyzed effect to assess. Keeping planning assumptions separate from observed evidence prevents a hypothetical calculation from being mistaken for a trial finding.
Finally, the record lists multiple secondary outcome topics and limited safety counts. Their presence shows the breadth of outcomes of interest, but not that all were analyzed. For clinical researchers and biostatisticians, this is a useful example of why outcome definitions, analysis completion, design, and reporting detail must be considered together before interpreting a trial’s evidential contribution.
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 immediate limitation is the accrued enrollment: only 4 patients were accrued, and no primary or secondary outcome analysis is reported. The registry does not provide participant-level data, endpoint summaries, estimates, confidence intervals, or p-values. The magnitude and precision of any association or treatment outcome therefore cannot be assessed.
The single-group design has no separate comparator, and allocation is listed as NA. Masking is listed as none. These features limit causal interpretation and do not support a like-for-like treatment comparison. The record does not report the reason for termination, so termination should not be attributed to a particular outcome, recruitment issue, or safety concern.
The primary endpoint description does not clarify which two samples would enter the named two-sample t-test. Nor does the registry report how an association would be established before considering a cut-point, how multiple cut-points would be handled, or whether a selected threshold would be validated. These are uncertainties in the analysis description, not proof that a particular procedure was omitted from the full study conduct.
The registry record also does not report a sample-size justification, analysis populations, missing-data procedures, or a multiplicity strategy. It lists secondary outcomes but provides no analysis results for them. The listed adverse-event figures are descriptive and do not provide a control-group comparison or detailed event histories. Taken together, these limits mean the record is informative about the trial’s stated design and outcomes of interest, but not about the estimated biomarker association or comparative treatment effects.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Orteronel in Treating Patients With Metastatic Hormone-Resistant Prostate Cancer — NCT01866423.
- Registry record last updated 2017-08-31; status last verified 2017-06.
- Results first posted 2017-08-31.
- 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
NCT01866423 is a phase 2, single-group trial of orteronel without prednisone for metastatic castration-resistant prostate cancer, sponsored by the University of Southern California. The registry lists the study start as 2013-10-25, primary completion as 2015-07-23, status as terminated, and enrollment of 4. The treatment description specifies orteronel 300 mg PO BID on days 1-28, with courses repeating every 28 days in the absence of progression or unacceptable toxicity.
The primary endpoint is AR protein expression levels in CTCs over up to 4 weeks. The registry describes a two-sample t-test and possible follow-up cut-point methods, but states that no data analysis was performed. It lists seven outcome measures and zero analyses. Safety entries include 1 of 4 participants affected by serious adverse events, 3 of 4 affected by other adverse events, and 0 deaths. The record does not report a randomized comparator, a trial-specific sample-size justification, or analyzed efficacy results.