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 Cabazitaxel Versus the Switch to Alternative AR Targeted Therapy Enzalutamide or Abiraterone in Metastatic Castration-Resistant Prostate Cancer (mCRPC) Primary Resistant Patients to Abiraterone or Enzalutamide (NCT02379390), a randomized phase 2 study. The primary outcome is Radiographic Progression-Free Survival (rPFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02379390 |
| Phase | Phase 2 |
| Condition | Prostate Cancer Metastatic |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sanofi |
| Results posted | Yes |
2. Clinical Question
Population
Chemotherapy-naïve participants with metastatic castration-resistant prostate cancer who had disease progression while receiving abiraterone plus prednisone or enzalutamide within 12 months of starting that therapy. The trial record reports an enrollment of 8.
Intervention
Cabazitaxel 25 mg/m^2 intravenously, with prednisone 10 mg orally on Day 1 of each 3-week treatment cycle. Treatment was described as continuing until disease progression, unacceptable toxicity, or refusal of further study treatment.
Comparator
A switch to the alternative androgen-receptor-targeted therapy: enzalutamide 160 mg once daily or abiraterone acetate 1000 mg once daily with prednisone 5 mg twice daily. The registry record describes the comparator as either treatment, rather than a single uniform drug.
Primary question
Would cabazitaxel improve radiographic progression-free survival compared with switching to the alternative targeted therapy? The planned endpoint ran from randomization to radiological tumor progression, bone-lesion progression, or death from any cause. The planned analysis could not be performed because the study ended early.
3. Trial Design
This was a phase II, randomized, open-label, multicenter study with a parallel-group design. It enrolled chemotherapy-naïve participants with metastatic castration-resistant prostate cancer whose disease had progressed during abiraterone or enzalutamide treatment within 12 months of treatment initiation. The registry record reports enrollment of 8 and a status of terminated.
Participants were assigned to cabazitaxel or to alternative androgen-receptor-targeted therapy. The cabazitaxel regimen was 25 mg/m^2 intravenously with prednisone 10 mg orally on Day 1 of each 3-week cycle. The comparator could be abiraterone acetate 1000 mg orally once daily with prednisone 5 mg orally twice daily from Day 1 to 21 of each 3-week cycle, or enzalutamide 160 mg orally once daily. The registry record does not report the allocation ratio used in the trial.
The primary objective was to demonstrate superiority in radiographic progression-free survival. Secondary objectives included PSA response and time to PSA progression, progression-free survival, overall survival, tumor response in participants with measurable disease, pain outcomes, symptomatic skeletal events, a circulating-tumor-cell biomarker analysis including AR-V7 messenger RNA, and safety. The listed secondary outcomes include PSA response, progression-free and overall survival, time to PSA progression, tumor response and its duration, pain response, and time to pain progression.
The primary completion date is recorded as 2018-05-10. The registry record says the planned primary analysis could not be performed because of early termination. It does not report why the study was terminated or whether termination followed a prespecified decision process.
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: Participants were randomized to receive either chemotherapy (cabazitaxel) or antiandrogen receptor targeted therapy (abiraterone or enzalutamide were assigned based on previous Androgen receptor \[AR\] targeted treatment in which participants previously treated with abiraterone were treated with enzalutamide and vice versa due to resistance).
Overall Study
| Stage | Cabazitaxel | Abiraterone Acetate or Enzalutamide |
|---|---|---|
| STARTED | 4 | 4 |
| COMPLETED | 2 | 2 |
| NOT COMPLETED | 2 | 2 |
Reasons for not completing this period:
| Reason | Cabazitaxel | Abiraterone Acetate or Enzalutamide |
|---|---|---|
| Adverse Event | 1 | 1 |
| Investigator's decision | 1 | 0 |
| Study Termination | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Planned analysis could not be performed due to early study termination.
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: All randomized participants who were exposed to at least one dose of study treatment.
| Characteristic | Unit | Cabazitaxel | Abiraterone Acetate or Enzalutamide | Total |
|---|---|---|---|---|
| Participants analysed | 4 | 4 | 8 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 0 | 1 |
| Age, Categorical: >=65 years | Participants | 3 | 4 | 7 |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 4 | 4 | 8 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 4 | 4 | 8 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): White | Participants | 3 | 4 | 7 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Radiographic Progression-Free Survival (rPFS), measured over Baseline until tumor progression or bone lesion progression or death due to any cause (maximum duration: 1059 days).
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
Radiographic progression-free survival (rPFS) measures the time from randomization until the first qualifying event: radiological tumor progression under RECIST version 1.1, progression of bone lesions under PCWG2 criteria, or death from any cause. The endpoint timeframe was baseline until one of these events, with a maximum duration of 1059 days.
Time-to-event endpoints such as rPFS can represent both whether an event occurs and how long participants remain free of the event. Including death from any cause means that death counts as an endpoint event even if radiographic progression has not been recorded. This can make the endpoint more comprehensive than a measure based only on tumor imaging, although it still depends on how progression is assessed and when participants are evaluated.
General explanation: A time-to-event endpoint is useful when the timing of an event matters and participants may have different lengths of follow-up. Analyses of such endpoints often account for participants whose event has not been observed by the end of their available follow-up. The registry record does not report the planned analysis details for handling those observations. In this trial, the planned rPFS analysis could not be performed, so the record does not give an estimated treatment effect or its precision.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical limitation is that the planned primary rPFS analysis could not be performed because of early study termination. The registry record therefore gives no comparative rPFS estimate, confidence interval, or test result. The stated objective was to test whether cabazitaxel was superior to switching to an alternative androgen-receptor-targeted therapy, but the posted information does not establish whether either treatment had better rPFS in this trial.
Enrollment was 8. With so few participants, any treatment comparison would ordinarily be expected to be highly imprecise, even if an estimate were available. However, no treatment-effect estimate is reported, so the size or direction of a possible difference cannot be described. The record also does not report an analysis population for the primary endpoint or the amount of follow-up available for each treatment group.
The secondary objectives cover several distinct outcomes, including PSA response, survival, tumor response, pain, and skeletal events. The registry record lists these outcomes but does not provide comparative analysis results for them. Their presence as planned outcomes does not substitute for an rPFS analysis, and no conclusion about their treatment comparisons can be drawn from the outcome list alone.
The safety information is descriptive. The registry record reports counts of participants affected by serious and other adverse events and lists several serious adverse-event terms with percentages. These figures can describe what was recorded among the small number of participants at risk, but they do not provide a precise comparison of safety between treatment strategies. The record reports no deaths in the listed groups.
Overall, the posted information documents the study question, design, early termination, and limited adverse-event counts. It does not provide the efficacy analysis needed to answer the primary comparative question. The absence of an estimate is not evidence that the treatments had the same effect; it means that the planned comparison is unavailable in the registry record.
9. Statistical Methods Explained
General explanation: Randomization is used to allocate participants to treatment groups by chance. When properly implemented, it can reduce systematic differences between groups at the outset, supporting a fair comparison. Randomization does not guarantee that groups will be similar in every characteristic, especially in a small study. The registry record identifies the study as randomized but does not report the sequence-generation method, concealment procedures, or allocation ratio.
The study was open-label, meaning treatment assignment was not masked from participants and study staff. In general, knowledge of treatment can influence care, reporting, or assessment, particularly for outcomes that require judgment. Radiographic progression uses defined RECIST version 1.1 and PCWG2 criteria, but the registry record does not describe whether image review was blinded or centrally assessed. It also does not report the schedule of tumor assessments.
What does a time-to-event comparison estimate?
General explanation: A time-to-event analysis compares the time until an event between groups while accounting for participants whose event has not been observed during their available follow-up. Such participants may be censored at their last known event-free assessment, subject to the analysis rules. The choice of time origin, event definition, censoring rules, and statistical model all affect interpretation. The registry record defines the rPFS time origin and events, but the planned statistical method and censoring rules are not reported.
A hazard ratio is one common summary for comparing event rates over follow-up, but its interpretation relies on assumptions about how the relative event rates behave over time. The registry record does not report a planned hazard-ratio model, an alternative summary measure, or checks of model assumptions. No hazard ratio or other primary effect estimate is posted, so there is no trial-specific estimate to interpret.
How should uncertainty be read?
General explanation: A confidence interval describes a range of effect values compatible with the observed data under a statistical procedure. A narrower interval indicates greater precision than a wider interval, while an interval that includes values corresponding to no difference may be compatible with more than one interpretation. A p-value, when reported, summarizes how unusual the data would be under a specified null model; it does not measure the probability that a treatment works. Neither a confidence interval nor a p-value for the primary rPFS comparison is reported in the registry record because the planned analysis could not be performed.
Small studies tend to yield limited precision because there is little information to distinguish treatment effects from random variation. With enrollment of 8, the study had few participants available for an outcome comparison. The record does not report the number of rPFS events or the follow-up distribution, so the information available for a time-to-event analysis cannot be assessed beyond the stated enrollment and early termination.
What do the planning illustrations mean?
General explanation: A sample-size calculation estimates the number of participants or events needed under stated assumptions. The registry record describes a planning illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. For time-to-event illustrations, the stated quantity is the total number of events; other illustrations refer to participants per arm. These are planning assumptions, not observed trial outcomes or evidence of achieved power. Because the planned primary analysis could not be performed, no observed rPFS treatment effect is available in the registry record to support an outcome-based interpretation of such an illustration.
In general, over-dispersion matters when outcome variability is greater than a model assumes: standard errors can be too small and uncertainty understated if the model fails to account for that extra variability. The registry record does not report an over-dispersion assessment or a statistical model for a count outcome. More broadly, it does not report a detailed statistical analysis plan, prespecified interim analyses, or model diagnostics. Those methods should not be inferred from the trial’s design label or its outcome list.
10. Multiplicity, Missing Data and Analysis Populations
The study listed a primary rPFS objective alongside numerous secondary objectives, including PSA response, time to PSA progression, progression-free survival, overall survival, tumor response, pain outcomes, skeletal events, biomarker analyses, and safety. When several outcomes are tested, the chance of at least one apparently notable result can increase unless the analysis plan accounts for multiple comparisons. The registry record does not report a multiplicity-control procedure, a hierarchy for testing secondary outcomes, or which outcomes would be considered confirmatory rather than exploratory.
The planned primary analysis could not be performed after early termination. The registry record does not report a completed comparative analysis for the secondary outcomes either. It also does not report the statistical analysis populations, such as whether analyses were intended to follow randomized assignment or to include only participants meeting specified treatment or assessment criteria. No missing-data methods or rules for handling incomplete outcome assessments are reported.
General explanation: Missing outcome data can affect an estimate when the likelihood of an observation being missing is related to prognosis or treatment experience. The impact depends on how much information is missing and why it is missing. For time-to-event outcomes, incomplete follow-up is often handled through censoring, but the assumptions and implementation matter. The registry record does not describe these procedures for the planned rPFS analysis. It also does not report whether any interim analyses were planned or conducted. In the absence of those details and a completed analysis, the possibility of selective reporting or the robustness of any treatment comparison cannot be evaluated from the registry 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 |
|---|---|---|---|
| Cabazitaxel | 1 | 4 | 25.0% |
| Enzalutamide or Abiraterone | 2 | 4 | 50.0% |
| Abiraterone | 0 | 1 | 0.0% |
| Enzalutamide | 2 | 3 | 66.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cabazitaxel | 0 of 4 |
| Enzalutamide or Abiraterone | 0 of 4 |
| Abiraterone | 0 of 1 |
| Enzalutamide | 0 of 3 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Cabazitaxel | 3 of 4 |
| Enzalutamide or Abiraterone | 2 of 4 |
| Abiraterone | 1 of 1 |
| Enzalutamide | 1 of 3 |
Most frequent serious adverse event terms
| Event term | Organ system | Cabazitaxel | Enzalutamide or Abiraterone | Abiraterone | Enzalutamide |
|---|---|---|---|---|---|
| Seizure | Nervous system disorders | 0 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Haematuria | Renal and urinary disorders | 0 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Pancytopenia | Blood and lymphatic system disorders | 1 of 4 | 0 of 4 | 0 of 1 | 0 of 3 |
| Fall | Injury, poisoning and procedural complications | 0 of 4 | 1 of 4 | 0 of 1 | 0 of 3 |
| Humerus Fracture | Injury, poisoning and procedural complications | 0 of 4 | 1 of 4 | 0 of 1 | 0 of 3 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cabazitaxel | Enzalutamide or Abiraterone | Abiraterone | Enzalutamide |
|---|---|---|---|---|---|
| Nausea | Gastrointestinal disorders | 1 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Vomiting | Gastrointestinal disorders | 1 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Skin Abrasion | Injury, poisoning and procedural complications | 1 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Diarrhoea | Gastrointestinal disorders | 2 of 4 | 0 of 4 | 0 of 1 | 0 of 3 |
| Oedema Peripheral | General disorders | 2 of 4 | 0 of 4 | 0 of 1 | 0 of 3 |
| Influenza | Infections and infestations | 0 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Fall | Injury, poisoning and procedural complications | 0 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Ligament Sprain | Injury, poisoning and procedural complications | 0 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Decreased Appetite | Metabolism and nutrition disorders | 0 of 4 | 1 of 4 | 0 of 1 | 1 of 3 |
| Hypophosphataemia | Metabolism and nutrition disorders | 0 of 4 | 1 of 4 | 1 of 1 | 0 of 3 |
Serious events with the highest arm-level rate: seizure (33.3%), haematuria (33.3%), pancytopenia (25.0%), fall (25.0%), humerus fracture (25.0%).
The adverse-event record reports 4 participants at risk in the cabazitaxel group, of whom 1 was affected by a serious adverse event and 3 by another adverse event. In the combined enzalutamide-or-abiraterone group, 4 participants were at risk, 2 were affected by a serious adverse event, and 2 by another adverse event. The registry also separates that comparator group: among participants receiving abiraterone, 1 was at risk, none were affected by a serious adverse event, and 1 was affected by another adverse event; among participants receiving enzalutamide, 3 were at risk, 2 were affected by a serious adverse event, and 1 by another adverse event. No deaths are reported in any of these groups.
The registry lists seizure and haematuria at 33.3% each, and pancytopenia, fall, and humerus fracture at 25.0% each, among the top serious adverse-event terms. The denominator and method used for these percentages are not reported in the registry record. The listed percentages should therefore be read as registry-reported values, not converted into a direct treatment comparison.
These are small descriptive counts, not a precise estimate of comparative safety. The figures do not establish that an event was caused by treatment, and the registry record does not provide the detail needed to compare event severity, timing, duration, or recurrence.
12. What the Result Does, and Does Not, Mean
The record establishes that investigators planned a randomized comparison of cabazitaxel against a switch to alternative androgen-receptor-targeted therapy, with radiographic progression-free survival as the primary endpoint. It also establishes that the trial was terminated and that the planned primary analysis could not be performed. Those details define what can and cannot be concluded from the posted results.
No rPFS treatment-effect estimate, confidence interval, or statistical test is reported. Consequently, the registry record cannot show whether the observed data favored cabazitaxel, favored the alternative therapy, or were compatible with a range of effects. It also cannot establish equivalence or absence of a difference. A study that does not produce its planned comparison does not demonstrate that the treatments have the same effect.
The enrollment of 8 and the adverse-event counts offer limited descriptive information. They do not replace the planned efficacy analysis, and they do not support precise comparative conclusions. The listed secondary outcomes likewise do not answer the primary question without reported outcome results and analyses.
General explanation: Statistical significance and clinical importance are different concepts. A statistically significant result can still represent a small effect, while an imprecise result may leave both meaningful benefit and little difference compatible with the data. Interpreting either requires an estimate and its uncertainty, neither of which is available for the primary comparison in this registry record.
The appropriate reading is therefore narrow: the trial’s design and intended question are documented, but its primary efficacy comparison is unavailable. The record also does not explain the reason for termination, so no particular cause or implication of the early termination should be assumed.
13. Why This Trial Matters Statistically
This trial illustrates a key distinction between a study’s planned question and the evidence available to answer it. A randomized design can be intended to support a comparative estimate, but the design alone does not produce an estimate. Here, the planned primary analysis of rPFS could not be performed after early termination, leaving the central comparison unresolved in the registry record.
It also shows why precision matters. A treatment comparison is not adequately described by its direction alone; readers need an estimate and an indication of uncertainty. With enrollment of 8, even a completed comparison would require careful attention to how much information the outcome data contained. The record does not report the number of rPFS events or a treatment-effect estimate, so the precision of the intended comparison cannot be evaluated.
The record also illustrates the limits of safety counts from a very small study. The reported adverse-event figures can describe events recorded among participants at risk, but they cannot provide a stable or definitive comparative safety profile. Registry-listed percentages for serious-event terms require context about their denominators, which is not reported.
Finally, a broad list of secondary outcomes does not by itself provide evidence across those outcomes. Without reported estimates, uncertainty, analysis populations, and methods for addressing multiple comparisons, the outcome list documents intent rather than results. Statistically, the most important finding is the absence of a completed primary comparison—not a demonstrated advantage or lack of advantage for either treatment strategy.
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 is that early termination prevented the planned rPFS analysis. The registry record reports enrollment of 8, but does not explain why the trial stopped, how the decision was made, or whether the planned duration of follow-up was reached. It therefore does not permit assessment of the reason for termination or its relationship to the available outcome data.
The record does not report a comparative estimate for the primary endpoint, the number of rPFS events, group-specific follow-up, or a confidence interval. It also does not report outcome results for the listed secondary objectives. Without these results, neither the size nor the precision of treatment differences can be assessed.
The comparator was not a single treatment: participants could receive enzalutamide or abiraterone acetate. The registry reports separate adverse-event counts for these options, but does not provide comparative efficacy results by comparator treatment. Any interpretation that treats the comparator as one uniform regimen would therefore miss this feature of the design.
The study was open-label. The record specifies radiographic criteria for progression but does not report whether outcome assessment was blinded, centrally reviewed, or performed on a stated schedule. It does not report allocation procedures, analysis populations, missing-data rules, the detailed statistical plan, or multiplicity handling. These omissions limit assessment of bias and reproducibility. The serious adverse-event percentages are listed without their denominator basis, and the small counts provide little precision for safety comparisons.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Cabazitaxel Versus the Switch to Alternative AR Targeted Therapy Enzalutamide or Abiraterone in Metastatic Castration-Resistant Prostate Cancer (mCRPC) Primary Resistant Patients to Abiraterone or Enzalutamide — NCT02379390.
- Registry record last updated 2019-06-21; status last verified 2019-06.
- Results first posted 2019-06-21.
- 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
NCT02379390 was a randomized, open-label, multicenter phase II parallel-group study of cabazitaxel versus a switch to enzalutamide or abiraterone acetate in chemotherapy-naïve participants with metastatic castration-resistant prostate cancer and primary resistance to prior androgen-receptor-targeted therapy. The registry record reports enrollment of 8 and study status as terminated.
The primary endpoint was radiographic progression-free survival, defined by radiological tumor progression, bone-lesion progression, or death from any cause. The planned primary analysis could not be performed because of early termination. The record does not report the reason for termination or a comparative primary outcome estimate. It lists secondary outcomes and descriptive adverse-event counts, including no deaths in the reported groups, but does not provide the planned efficacy comparison.