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 Safety and Efficacy Study to Evaluate Proellex in the Treatment of Premenopausal Women With Symptomatic Endometriosis (NCT00556075), a randomized phase 2 study. The primary outcome is Difference Between the 50 mg Proellex Group and Placebo Group in the Month 4 Subject Diary Composite Pain Score.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00556075 |
| Phase | Phase 2 |
| Condition | Endometriosis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 67 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Repros Therapeutics Inc. |
| Results posted | Yes |
2. Clinical Question
Population
Premenopausal women with symptomatic endometriosis were the population described in the study title and summary. Endometriosis is the listed condition. The record reports enrollment of 67 participants, but it does not provide further details about eligibility criteria, baseline characteristics, or how closely the enrolled group represented the broader population of interest.
Intervention
The study evaluated Proellex at 25 mg and 50 mg, each taken once daily. It was a Phase II dose-ranging study, so the two active-dose groups allowed the registry question to include different dose levels. The record does not report treatment adherence or the amount of treatment actually received before termination.
Comparator
The comparator was placebo taken once daily. The study was randomized, parallel-group, and placebo-controlled. The record does not describe the allocation procedure or say whether allocation was equal across all three groups.
Primary question
The primary comparison was the difference between the 50 mg Proellex group and the placebo group in the Subject Diary Composite Pain Score at Month 4. The timeframe is listed as 4 months. No participants were analyzed for this endpoint because no data were collected due to early termination, so the registry record does not establish what the comparison would have shown.
The clinical question was whether daily Proellex, particularly at the 50 mg dose, was associated with a different diary-based composite pain score at Month 4 than placebo among premenopausal women with symptomatic endometriosis. The study also listed secondary questions about changes in the composite score at monthly visits, time to pain-free assessments, duration of pain-free assessments, and days with pain.
These questions depend on participants having diary observations over the relevant period. Since the record states that no data were collected for the primary endpoint, there is no posted treatment-effect estimate for that comparison. The registry record describes the question the trial set out to address, but it does not provide evidence from the primary endpoint that can answer it.
3. Trial Design
This was a Phase II, randomized, three-arm, parallel-group, dose-ranging, placebo-controlled study. The record describes it as multicenter and triple-masked. The interventions were Proellex 25 mg once daily, Proellex 50 mg once daily, and placebo once daily. A parallel design assigns participants to a treatment group and follows those groups during the trial, rather than having each participant receive each intervention in sequence. The registry record does not provide details of the allocation sequence or identify which trial roles were masked.
The record lists enrollment of 67. It gives a study start of 2007-11 and a primary completion date of 2009-05. The status is terminated. These dates describe the record’s study milestones; they do not indicate that participants completed the planned follow-up or that the primary endpoint was measured. The primary endpoint description specifically states that no data were collected because of early termination.
The study compared two active dose levels with placebo, with the primary comparison specified as 50 mg versus placebo. The record does not explain why that dose was selected for the primary comparison, nor does it describe how the 25 mg arm was intended to contribute to the primary analysis. It also does not report the planned treatment duration beyond the primary endpoint timeframe, participant flow, reasons for termination, or the number of participants who received each intervention.
The record identifies Repros Therapeutics Inc. as sponsor. It lists six outcome measures and zero analyses. No statistical analysis plan, protocol details, or sample-size justification is reported in the registry record. The design features describe how the trial was organized, but they do not substitute for outcome data. Because the primary endpoint had no analyzed participants, the registry record cannot provide a randomized comparison of pain scores.
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 | C Placebo | A 25 mg | B 50 mg |
|---|---|---|---|
| STARTED | 22 | 22 | 23 |
| COMPLETED | 9 | 13 | 15 |
| NOT COMPLETED | 13 | 9 | 8 |
Reasons for not completing this period:
| Reason | C Placebo | A 25 mg | B 50 mg |
|---|---|---|---|
| Lost to Follow-up | 3 | 0 | 3 |
| Withdrawal by Subject | 3 | 3 | 0 |
| Protocol Violation | 1 | 1 | 3 |
| Not eligible | 1 | 1 | 2 |
| Adverse Event | 1 | 2 | 0 |
| Personal issues | 4 | 1 | 0 |
| Endometrial stripe not viewed on 2 tvu | 0 | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Zero participants were analyzed because no data were collected due to early 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: Safety population
| Characteristic | Unit | Placebo | 25 mg | 50 mg | Total |
|---|---|---|---|---|---|
| Participants analysed | 22 | 22 | 23 | 67 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 22 | 22 | 23 | 67 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 22 | 22 | 23 | 67 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 22 | 22 | 23 | 67 |
6. Primary Endpoint
The registry lists the primary outcome as Difference Between the 50 mg Proellex Group and Placebo Group in the Month 4 Subject Diary Composite Pain Score, measured over 4 months.
| 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 was the difference between the 50 mg Proellex group and placebo in the Month 4 Subject Diary Composite Pain Score. A composite score combines information across components into a single measure; a diary-based score uses entries recorded by participants rather than relying solely on a later recollection. Such a measure can capture participants’ experiences over time and can be useful when symptoms vary from day to day.
The intended endpoint was assessed at Month 4, with the timeframe also stated as 4 months. The registry record does not define the score’s components, scoring range, direction, interpretation, minimum meaningful change, or method for summarizing diary entries. It does not explain how incomplete diary entries would have been handled, or how the difference between groups was to be estimated. Those details are not reported in the registry record.
A between-group comparison is intended to distinguish changes associated with assignment to the study interventions from changes that may occur in both groups over time. The placebo group provides a reference under the trial conditions; randomization is intended to support comparability between assigned groups, while masking can limit some influences on reporting and assessment. These are general design purposes, not evidence that such protections succeeded in this trial.
Most importantly, the registry states that zero participants were analyzed because no data were collected due to early termination. Thus, the planned endpoint is identifiable, but its observed value and treatment contrast are unavailable. There is no posted estimate of the Month 4 score difference to interpret.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The key interpretive fact is that the primary outcome has no analyzed observations. The registry record names the intended comparison—50 mg Proellex versus placebo for the Month 4 Subject Diary Composite Pain Score—but says that zero participants were analyzed because no data were collected due to early termination. This is not a result showing a small effect, a null effect, or equivalent scores. It is an unavailable efficacy comparison.
There is consequently no primary treatment-effect estimate, confidence interval, or p-value reported in the registry record. Without an estimate, readers cannot assess the direction or magnitude of a difference. Without a confidence interval, they cannot assess the range of effects compatible with the data. Without a reported test result, they cannot evaluate statistical evidence against a specified null hypothesis. These are absences of outcome information, not indications that the groups had identical outcomes.
The record lists secondary pain outcomes, including composite pain scores at monthly visits, time to pain-free assessments, duration of pain-free assessments, and days with pain. Listing an outcome does not mean that it was measured or analyzed. The record reports six outcome measures and zero analyses, and it does not post estimates for these secondary questions. No conclusions about those outcomes can be drawn from their titles alone.
The adverse-event information is separate from the unobserved primary efficacy endpoint. The record lists serious adverse events and other adverse events by group. These counts describe events recorded for the listed risk groups; they do not supply a comparative efficacy estimate and do not establish that an event was caused by an intervention. The registry also lists serious-event terms with percentages, but the context for those percentages is not reported in the registry record.
The randomized, triple-masked design describes intended safeguards against bias, but design labels cannot replace completed outcome collection. The record does not report whether the planned allocation, masking, follow-up, or analysis procedures were fully implemented before termination. It also does not report reasons for termination. Interpretation should therefore distinguish the planned study question from the evidence actually posted: the question was specified, but the primary pain comparison is not available.
The planning assumptions described in the record concern hypothetical sample-size illustrations based on an observed effect and specified design assumptions. Such illustrations are not observed power and cannot recover a missing treatment effect. Since the primary endpoint has no collected data, there is no observed primary effect in the registry record on which to base a clinical interpretation.
9. Statistical Methods Explained
The registry record identifies the broad design but does not report the detailed statistical methods used for outcome analysis. General explanations of the methods concepts below clarify what the design and endpoint would ordinarily involve; they should not be read as a claim that a particular analysis was carried out in this trial.
What does randomization contribute?
In general, randomization uses a chance-based process to assign participants to study groups. Its purpose is to reduce systematic differences in participant characteristics across assigned groups, including differences that may not be measured. It supports a fair comparison when outcomes are collected and analyzed according to a suitable plan. Randomization does not guarantee that the groups are identical, and it does not address problems caused by missing outcome data or early termination. The registry record says the study was randomized but does not report the sequence-generation or allocation-concealment procedures.
What does masking mean for interpretation?
The study is described as triple-masked. In general, masking is intended to limit the influence of knowledge about assigned treatment on participant reporting, clinical care, or outcome assessment. The record does not say which roles were masked, how masking was maintained, or whether it was assessed. A masking label therefore describes a design feature, not proof that expectations had no influence on diary recording or other aspects of the trial.
How should a composite diary score be understood?
In general, a composite endpoint combines multiple measurements or symptom components under a defined scoring rule. A diary can record symptoms close to when they occur, which may reduce reliance on retrospective recall. Interpretation depends on the score definition: component selection, weighting, direction, aggregation, and handling of missing entries all matter. Those details are not reported in the registry record. Without them, the clinical meaning of a score difference cannot be assessed independently, even if an estimate were available.
The endpoint calls for a comparison of assigned groups at Month 4. A statistical estimate would ordinarily summarize the difference in scores under a specified analysis population and model. A confidence interval, in general, conveys uncertainty around an estimate and the range of values reasonably compatible with the data under its assumptions. It is not a guarantee that the true effect lies within the interval. A p-value, in general, describes how incompatible the observed data are with a stated null model, assuming that model and the analysis assumptions apply. Neither is reported for the primary endpoint in this record because no data were collected for analysis.
Why do repeated visits and diary observations require a plan?
The secondary outcomes refer to monthly visits and diary-recorded pain. Repeated observations from the same participant are generally related, rather than independent. An analysis of such data may need to account for within-participant association, the timing of measurements, and differences in the amount of observed information. The registry record does not state what model or summary method was planned. It also does not report how diary periods or monthly observations would have been defined for participants with incomplete follow-up.
Time to a pain-free assessment and duration of pain-free assessments raise additional general methodological questions. Time-to-event methods may be used when the outcome is the time until a defined event, but the event definition, censoring rules, and analysis approach need to be specified. Duration measures require rules for identifying when a pain-free period begins and ends. The registry lists these outcomes but does not report those analytic definitions or any results.
What does over-dispersion mean in general?
For count outcomes, variability can exceed what a simple probability model assumes; this is called over-dispersion. When present, it can make conventional standard errors too small and uncertainty appear less than it is. General remedies include models that allow extra variability or robust variance estimates, selected according to the outcome and design. The registry lists days with pain as a secondary outcome, but it does not describe a count model, report evidence of over-dispersion, or state that any such correction was used. This concept is relevant as a general consideration, not a description of the trial’s analysis.
What can the sample-size assumptions tell readers?
The registry describes planning illustrations based on an observed effect, a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect; for time-to-event illustrations, the reported quantity is a total number of events, while other illustrations refer to participants per arm for 80% power or another stated power level. These are planning illustrations, not observed power, and they are not the trial’s own design justification. Since the primary endpoint has no collected observations, these assumptions do not provide a missing efficacy result. The registry record does not report the trial’s original sample-size justification.
In general, a planning calculation depends on the assumed effect, variability, allocation, significance criterion, and desired power. A change in assumptions changes the resulting planning requirement. Such calculations can help frame future study planning, but they should not be interpreted as evidence that a completed trial had a particular probability of detecting an effect after the fact. No specific sample-size result is needed to interpret the central limitation: the record reports no primary endpoint data.
10. Multiplicity, Missing Data and Analysis Populations
The record lists six outcome measures, including the primary Month 4 composite pain comparison and secondary questions about pain scores, pain-free assessments, and days with pain. Considering several endpoints or repeated assessments raises a general multiplicity issue: when many hypotheses are examined, the chance of at least one apparently notable finding can increase. Prespecified testing hierarchies, adjustment procedures, or a clearly defined primary outcome can help structure interpretation. The registry record does not report a multiplicity strategy or a detailed statistical analysis plan.
The existence of a named primary endpoint does not establish how secondary outcomes were to be tested, whether repeated monthly comparisons were planned, or how results would have been prioritized. The record reports zero analyses, and no endpoint estimates or inferential results are posted. Therefore, there is no set of observed tests to evaluate for multiplicity and no basis for selecting a favorable outcome from among the listed measures.
Missing data are especially consequential because the registry explicitly says no data were collected for the primary endpoint due to early termination. This is not a case in which the record describes partial Month 4 observations and an approach for handling some missing values. It does not report any imputation method, model-based missing-data procedure, sensitivity analysis, or assumptions about why data were absent. The reason for early termination is also not reported in the registry record.
The record does not describe the analysis population, such as whether the intended primary analysis would include all randomized participants or a defined subset. It gives a group-level risk count for adverse-event reporting, but those counts do not define the population for the uncollected efficacy endpoint. Without outcome observations, analysis-population rules and missing-data assumptions cannot produce a primary treatment comparison.
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 |
|---|---|---|---|
| Placebo | 1 | 22 | 4.5% |
| 25 mg | 0 | 22 | 0.0% |
| 50 mg | 1 | 23 | 4.3% |
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 |
|---|---|
| Placebo | 18 of 22 |
| 25 mg | 22 of 22 |
| 50 mg | 22 of 23 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | 25 mg | 50 mg |
|---|---|---|---|---|
| Elevated LFTs | Investigations | 0 of 22 | 0 of 22 | 1 of 23 |
| Grand Mal Seizure | Nervous system disorders | 1 of 22 | 0 of 22 | 0 of 23 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | 25 mg | 50 mg |
|---|---|---|---|---|
| Ovarian cyst | Reproductive system and breast disorders | 16 of 22 | 10 of 22 | 15 of 23 |
| Nausea | Gastrointestinal disorders | 3 of 22 | 8 of 22 | 11 of 23 |
| Bone density decreased | Investigations | 2 of 22 | 4 of 22 | 11 of 23 |
| Adominal pain | Gastrointestinal disorders | 5 of 22 | 3 of 22 | 8 of 23 |
| Headache | Nervous system disorders | 1 of 22 | 4 of 22 | 6 of 23 |
| Hot flush | Vascular disorders | 0 of 22 | 4 of 22 | 7 of 23 |
| URI | Infections and infestations | 4 of 22 | 1 of 22 | 4 of 23 |
| Vulvovaginal mycotic infection | Infections and infestations | 2 of 22 | 1 of 22 | 3 of 23 |
| Dizziness | Nervous system disorders | 0 of 22 | 2 of 22 | 4 of 23 |
| Vomiting | Gastrointestinal disorders | 1 of 22 | 3 of 22 | 1 of 23 |
Serious events with the highest arm-level rate: grand mal seizure (4.5%), elevated lfts (4.3%).
The registry lists serious adverse events by group. The placebo group has 1 affected participant among 22 at risk, the 25 mg group has 0 among 22 at risk, and the 50 mg group has 1 among 23 at risk. These are descriptive counts in the registry record. They do not by themselves establish a difference between groups or show that an event was caused by the assigned intervention.
For other adverse events, the record lists 18 affected participants among 22 at risk in the placebo group, 22 among 22 in the 25 mg group, and 22 among 23 in the 50 mg group. These counts are reported separately from the serious-event counts. The record does not provide event-level timing, duration, severity classifications beyond the serious-event category, exposure-adjusted rates, or a statistical comparison.
The listed serious-event terms are Grand Mal Seizure at 4.5% and Elevated LFTs at 4.3%. The registry record does not report the denominator or further context for those term-level percentages, so they should be read as reported rather than recalculated or mapped to a particular group. Death counts are not reported in the registry record.
Adverse-event counts are not equivalent to a causal safety assessment. Interpretation would depend on event definitions, collection procedures, exposure, timing, and comparative analysis. Those details are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The registry record establishes that the study was designed to compare daily Proellex at two doses with daily placebo in premenopausal women with symptomatic endometriosis. It identifies a primary diary-based pain endpoint and lists additional pain-related outcomes. It also reports group-level adverse-event counts. These registry entries describe the study question, design, and some safety reporting.
For the primary efficacy question, the record does not establish whether the Month 4 composite pain score differed between 50 mg Proellex and placebo. It reports zero analyzed participants because no data were collected due to early termination. Accordingly, the record does not support a claim of benefit, lack of benefit, equivalence, or a particular direction of effect. An absent estimate is not evidence that the treatment groups had the same outcomes.
The study’s randomized and masked design features describe intended methods for reducing bias. They do not demonstrate that an outcome effect exists, and they cannot overcome the absence of primary endpoint observations. Likewise, the number enrolled and the listed interventions do not provide a substitute for observed pain scores. The registry record does not report the reason for termination or enough detail to reconstruct what follow-up occurred before the study ended.
The adverse-event figures are descriptive and should not be treated as proof of causation or as a complete comparative safety analysis. The record does not supply the analytic detail needed to assess exposure-adjusted event rates or uncertainty around group differences. Term-level percentages are reported, but their denominator and context are not stated.
In general, a clinical trial can answer its intended question only to the extent that relevant outcomes are collected and analyzed under interpretable methods. In this case, the registered primary question is clear, but its answer is not available in the record. Readers should distinguish the trial’s planned comparison from findings that the posted results actually support.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between a planned endpoint and an observed result. The registry gives a specific primary question: compare the Month 4 Subject Diary Composite Pain Score between the 50 mg Proellex group and placebo. Yet it also states that no participants were analyzed because no data were collected due to early termination. A clearly named endpoint does not become an estimate simply because the design and comparison are specified.
The record also illustrates why trial status and outcome availability matter when interpreting a randomized design. Randomization and masking can support a credible comparison when outcome information exists and the analysis is appropriate. When the primary endpoint has no collected data, those design strengths cannot yield an effect estimate, quantify uncertainty, or answer the clinical question.
The three-arm, dose-ranging structure adds another interpretive consideration. The primary question focused on the 50 mg group versus placebo, while the record also lists a 25 mg group and several secondary pain outcomes. Without a reported analysis plan, readers cannot establish how the dose comparison and multiple outcomes were to be handled. The registry reports zero analyses, so no pattern across doses or outcomes can be evaluated.
The safety counts provide a separate, limited form of information. They describe events recorded in the listed groups, but do not resolve the absent efficacy comparison or establish causality. This distinction is useful more broadly: outcome domains need their own evidence and methods, and descriptive safety reporting should not be substituted for an efficacy result.
Finally, the record’s planning assumptions should be kept separate from trial findings. Planning illustrations can show how assumptions relate to future study size, but they cannot recreate observations that were never collected. The statistical significance of this record lies chiefly in its transparent limits: it records the intended question and the absence of data needed to answer it.
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 direct limitation is that the primary outcome has no analyzed participants because no data were collected due to early termination. As a result, the registry record contains no primary estimate of the Month 4 composite pain difference. There is no reported confidence interval, p-value, or other inferential result for that comparison.
The record does not explain why the study was terminated, how much follow-up occurred before termination, or whether any participants had partial diary data that were not usable for the primary endpoint. It does not report participant flow, adherence, treatment exposure, baseline characteristics, or the numbers assigned to each intervention. These omissions limit understanding of the conduct and context of the trial.
Important measurement details are also absent. The registry does not define the composite pain score, its components, scoring direction, or the handling of incomplete diary entries. It does not describe the statistical model, analysis population, missing-data methods, or sensitivity analyses. A detailed statistical analysis plan and the original sample-size justification are not reported in the registry record.
The record lists six outcome measures but zero analyses. It does not report how multiple outcomes or repeated monthly assessments would have been addressed. Consequently, readers cannot assess the consistency of results across outcomes or the intended hierarchy of testing. The listed adverse-event counts are descriptive, and the registry does not give the detail needed for a full comparative assessment. The term-level serious-event percentages are reported without their denominator or context, and deaths are not reported in the registry record.
These limitations do not indicate what the unobserved results would have been. They restrict interpretation to the documented design, endpoint definitions at the level recorded, and descriptive safety counts.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Efficacy Study to Evaluate Proellex in the Treatment of Premenopausal Women With Symptomatic Endometriosis — NCT00556075.
- Registry record last updated 2014-08-25; status last verified 2014-08.
- Results first posted 2014-08-25.
- 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
NCT00556075 is a Phase II, randomized, triple-masked, parallel, multicenter, placebo-controlled, dose-ranging study of Proellex in premenopausal women with symptomatic endometriosis. The interventions were Proellex 25 mg once daily, Proellex 50 mg once daily, and placebo once daily. Enrollment was 67. The study start is listed as 2007-11, primary completion as 2009-05, and status as terminated.
The primary endpoint was the difference between the 50 mg group and placebo in the Month 4 Subject Diary Composite Pain Score. The record states that zero participants were analyzed because no data were collected due to early termination. It lists six outcome measures and zero analyses. Secondary outcomes concern pain scores, pain-free assessments, and days with pain.
The record also reports serious and other adverse-event counts by group, plus two serious-event terms with percentages. It does not report a primary efficacy estimate or the reason for termination.