Safety and Efficacy of Telapristone Acetate (Proellex®) in the Treatment of Pre-Menopausal Women With Confirmed, Symptomatic Endometriosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of Telapristone Acetate (Proellex®) in the Treatment of Pre-Menopausal Women With Confirmed, Symptomatic Endometriosis (NCT01728454), a randomized phase 2 study. The primary outcome is Change From Baseline in Individual Biberoglu Behrman Symptom Severity Scale (BBSS) Score for Dysmenorrhea.

2. Clinical Question

The trial focused on symptom severity in premenopausal women with confirmed symptomatic endometriosis. Its stated purpose was to evaluate the safety and efficacy of two oral doses of telapristone acetate. The primary measure was participant-reported dysmenorrhea severity, recorded in daily diaries and expressed on a standardized 28-day basis. Negative change from baseline is defined as improvement on this measure, but the direction and size of the trial’s observed changes are not reported in the registry record.

3. Trial Design

This was a Phase 2, multi-center, randomized, double-blind, parallel-design study with three Stage 2 arms: placebo, telapristone acetate 6 mg and telapristone acetate 12 mg. The registry records quadruple masking. Enrollment was 60. The study started on 2013-05-02, had a primary completion date of 2017-03-15 and is recorded as completed.

The arm descriptions include a no-treatment baseline assessment period in Stage 1, followed by Stage 2 dosing. Placebo and 6 mg were taken once daily for 18 weeks; the 12 mg arm description also specifies an 18-week course. Eligible participants had the option of additional active-treatment cycles in Stage 3. The descriptions refer to two additional 16-week cycles, separated by an off-drug interval. The placebo description specifies active treatment at 12 mg/day in those additional cycles; the 6 mg and 12 mg descriptions specify active treatment at their respective doses. These optional extensions mean that Stage 3 safety groups are not simply the original Stage 2 randomized comparisons.

The primary outcome timeframe compares baseline with the last day of dosing in Cycle 1 and with the end of Off-drug Cycle 1, described as three weeks following On-drug Cycle 1. The registry record does not report the detailed allocation procedure, how eligibility for optional additional cycles was determined, or the statistical plan for comparing the three Stage 2 arms. The listed enrollment is not a statement of how many participants contributed data to each endpoint analysis.

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.

Stage 1 and 2

Reasons for not completing this period:

Stage 3

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent-to-Treat (ITT) population included all participants who were randomized and received study drug.

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 included all study participants who were randomized, received study drug, and had some post-baseline safety data.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Individual Biberoglu Behrman Symptom Severity Scale (BBSS) Score for Dysmenorrhea, measured over Baseline (28-day Baseline Menstrual Cycle) to the last day of dosing in Cycle 1 (On-drug Cycle 1 is 18 weeks) and at the end of Off-drug Cycle 1 (Off-drug Cycle 1 is 3 weeks following On-drug Cycle 1).

The primary endpoint is change from baseline in the individual Biberoglu Behrman Symptom Severity Scale (BBSS) score for dysmenorrhea. The scale captures dysmenorrhea in terms of loss of work efficiency and need for bed rest. Scores range from 0 to 3: 0 means none; 1 means mild, with some loss in work efficiency; 2 means moderate, with part of the day in bed and occasional loss of work efficiency; and 3 means severe, with one or more days in bed and incapacitation. Higher scores indicate more severe symptoms.

Participants recorded endometriosis pain scores each day in a diary. For each interval, daily scores were standardized to a 28-day period by taking the sum of scores in that interval, dividing by the number of days in the interval and multiplying by 28. The endpoint therefore expresses dysmenorrhea symptom burden on a common period basis, allowing the baseline interval and later intervals of different lengths to be described on the same scale. A negative change from baseline indicates improvement in the score; that definition describes the scale’s direction, not the trial’s observed result.

Repeated symptom recording can capture change over time that a single measurement might miss. The registry record does not report the endpoint’s numerical group results, uncertainty intervals or statistical tests.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean change describe?

The primary endpoint is a continuous measure: the BBSS dysmenorrhea score is converted to a standardized score per 28-day period, and change from baseline is assessed. A mean change describes the average score change in a group. It does not show how every participant changed, and it can conceal variation between participants. The registry lists the endpoint parameter as a mean and its dispersion as a standard deviation, but does not report the numerical group estimates for the primary endpoint.

General explanation: the standard deviation describes how dispersed observations are around their group mean. It is not the same as the uncertainty in the mean. The uncertainty in a mean also depends on the amount of information contributing to the estimate and on the analysis assumptions. Without endpoint group counts and estimates, the degree of uncertainty cannot be reconstructed from the registry record.

How should the score direction be read?

The scale runs from 0, none, to 3, severe, with higher scores indicating more severe symptoms. The endpoint is change from baseline, and the registry states that a negative change indicates improvement. The measure is standardized by summing daily scores in an interval, dividing by the interval’s number of days and multiplying by 28. This places measurements from intervals of different lengths on a 28-day basis. It does not convert the score into a percentage or establish that the intervals are otherwise interchangeable.

What does randomization contribute?

Random allocation is intended to create groups that can be compared while limiting systematic differences in assigned treatment. This is a general design principle; the registry record does not describe the sequence-generation or allocation-concealment procedures. The parallel design assigns participants to groups for concurrent comparison rather than describing a crossover comparison. The record reports quadruple masking, but does not specify which roles were masked or how masking was maintained.

Randomization does not by itself guarantee balanced groups, complete follow-up or an unbiased result under every analysis. The estimate’s interpretation also depends on who was included and how outcomes that were not observed were handled. The primary endpoint population is defined as randomized participants who received study drug. The registry record does not report the number included in each endpoint analysis or the handling of missing primary measurements.

What can the posted safety counts tell readers?

The safety information separates serious adverse events, other adverse events and deaths, and lists groups by treatment and stage. General explanation: an at-risk count is the denominator for interpreting the number of participants affected in that group. The registry reports zero serious adverse events in each listed group and gives counts for other adverse events. Such counts describe observed reports in the listed groups; they do not, on their own, quantify comparative risk with uncertainty or establish why an event occurred. The record’s Stage 3 groups reflect optional additional active-treatment cycles and should be read separately from the original Stage 2 arms.

What are the planning illustrations?

The sample-size assumptions describe planning illustrations based on the observed effect, rather than the trial’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation; the effect to detect is a stated fraction of the observed effect. For non-time-to-event outcomes, the illustrations are expressed as participants per arm for 80% or 90% power. These are planning quantities, not observed power, and they are not the trial’s enrollment or analysis counts.

General explanation: a planning calculation asks how much information might be needed to detect a specified effect under stated assumptions. Its result is conditional on those assumptions, including the chosen effect size and variability. It does not describe what the completed trial actually found. The registry record does not report the original design’s sample-size justification, and the primary endpoint result is not reported numerically, so no conclusion about the trial’s original planning rationale can be drawn from these illustrations.

Why does multiplicity matter?

The registry lists multiple outcomes and analyses, while the primary outcome includes more than one time point. General explanation: when several outcomes, time points or comparisons are examined, the chance of a false-positive finding can increase if each is tested without an appropriate strategy. A statistical plan may specify a primary comparison, ordering, or adjustment, but the registry record does not report such a plan for these analyses. The posted endpoint description alone is not enough to determine whether or how multiplicity was addressed.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures and 44 analyses. The primary outcome is reported across more than one time point, and the record notes that it was not reduced to one comparison. The registry record does not report a multiplicity strategy, such as a prespecified ordering of comparisons or an adjustment for testing multiple outcomes, time points or treatment contrasts. General explanation: when many statistical tests are considered, interpreting an isolated result without knowing the analysis plan can be misleading because the number and selection of tests affect how results should be understood.

The endpoint population is described as the Intent-to-Treat population, defined in the record as all participants who were randomized and received study drug. This definition does not establish how many participants were included at each time point. The registry record does not report the amount or pattern of missing primary endpoint data, the reasons for missingness, or the method used to handle missing observations. It also does not state whether analyses used any additional populations or sensitivity analyses.

General explanation: missing data can affect estimates if participants with unavailable measurements differ systematically from those with observed measurements. Statistical methods for missing data rely on assumptions, and different assumptions can lead to different interpretations. Because the registry record does not describe the missing-data approach, readers cannot assess its assumptions from this information.

The registry record also does not report the prespecified statistical analysis plan, the primary treatment contrast or whether adjustment for baseline measurements or other variables was used. These omissions limit assessment of how the listed analyses relate to the original study questions. They do not establish that a particular method was or was not used; they mean that the method is not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse event figures are reported by group and stage. In Stage 2, the registry records 0 serious adverse events among 17 at risk in the placebo group, 0 among 20 at risk in the telapristone acetate 6 mg group, and 0 among 23 at risk in the telapristone acetate 12 mg group. It also records 0 deaths in each of those groups. For other adverse events, it reports 14 affected among 17 at risk with placebo, 17 among 20 at risk with 6 mg, and 18 among 23 at risk with 12 mg.

Stage 3 is reported separately: the placebo-to-telapristone acetate 12 mg group had 0 serious adverse events among 6 at risk and 4 participants affected by other adverse events; the 6 mg group had 0 serious adverse events among 5 at risk and 5 affected by other adverse events; the 12 mg group had 0 serious adverse events among 11 at risk and 6 affected by other adverse events. No deaths are recorded in these groups.

These are counts for the listed groups, not estimates of comparative risk with uncertainty. General explanation: zero recorded serious events in a group does not prove that the underlying risk is zero. Stage 3 involved optional additional active-treatment cycles, so those groups should not be interpreted as equivalent to the Stage 2 randomized arms. The registry record does not list serious adverse event terms.

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

The registry record establishes that this completed Phase 2 study was designed to assess two oral doses of telapristone acetate against placebo in premenopausal women with symptomatic endometriosis. It identifies a daily-diary symptom measure, its scoring direction and assessment periods, and reports safety counts by group and stage. These details help define what was to be measured and how the listed safety observations are organized.

However, the primary endpoint’s numerical findings are not reported in the registry record. Without group-level change estimates, variability, comparison estimates or confidence intervals, the record does not show the size or precision of any difference in dysmenorrhea scores. The fact that the endpoint defines a negative change as improvement does not mean that an improvement was observed. Likewise, the study’s randomized and masked design describes its framework, not its outcome.

The safety counts show no reported serious adverse events or deaths in the listed groups, alongside counts of participants affected by other adverse events. Those observations apply to the groups and stages as recorded. They are not a complete characterization of possible risks, and they do not establish a causal relationship between treatment and any event.

General explanation: statistical evidence is strongest when estimates are read together with their uncertainty, analysis population and methods. Those details are not fully reported for the primary endpoint in the registry record. The record also does not report how missing measurements or multiple comparisons were handled. Accordingly, it is not possible to draw a statistical conclusion about the primary endpoint from the available registry information alone. This is a limitation of what is reported, rather than evidence for a particular treatment effect or absence of effect.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a symptom endpoint can be operationalized. Dysmenorrhea was scored daily using a scale tied to work efficiency and bed rest, then standardized to a 28-day period. The endpoint definition specifies both the scale’s interpretation and the direction of change, which are essential for reading a reported estimate correctly. The planned observations also span baseline, an on-drug period and an off-drug period.

The design includes three Stage 2 arms, randomized allocation, quadruple masking and a parallel structure. Those features describe how the comparison was organized. The registry also describes optional further active-treatment cycles, making it important to keep Stage 3 safety groups distinct from the Stage 2 randomized arms when interpreting the record.

At the same time, this record illustrates why outcome definitions and design information are not a substitute for numerical results. The primary endpoint’s group estimates and uncertainty are not reported, and the record notes multiple categories or time points rather than one reduced comparison. The registry also does not report how multiplicity or missing endpoint data were addressed. These gaps prevent a complete statistical appraisal of the symptom findings.

General explanation: transparent reporting of estimates, uncertainty, analysis populations and methods allows readers to distinguish the observed data from the assumptions used to interpret them. The record supplies important design and measurement context, but its missing primary endpoint results constrain what can be learned about the trial’s comparative efficacy from the registry information.

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 main trial-specific limitation is that the registry record does not report numerical results for the primary BBSS dysmenorrhea endpoint. It describes the outcome and its time points but gives no group means, standard deviations, between-group estimates, confidence intervals or p-values for those measurements. The record’s note that the outcome has several categories or time points and was not reduced to one comparison further means there is no single reported primary contrast to interpret.

The registry defines the primary endpoint population as randomized participants who received study drug, but does not report the number analyzed at each time point or the extent and pattern of missing measurements. The missing-data method and any sensitivity analyses are not reported in the registry record. The statistical analysis plan, multiplicity approach and detailed randomization procedures are also not reported.

Although enrollment is recorded as 60, that figure does not establish the number of participants contributing to any specific endpoint estimate. The optional Stage 3 treatment cycles also mean that Stage 3 safety groups are not equivalent to the initial randomized Stage 2 groups. The record does not provide a statistical comparison of safety outcomes or uncertainty intervals for the reported counts. These limitations concern the detail available in the registry record and should not be mistaken for evidence about unreported outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of Telapristone Acetate (Proellex®) in the Treatment of Pre-Menopausal Women With Confirmed, Symptomatic Endometriosis — NCT01728454.
• Registry record last updated 2019-07-23; status last verified 2019-07.
• Results first posted 2019-07-23.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

This completed Phase 2 randomized, double-blind, parallel study evaluated oral telapristone acetate at 6 mg and 12 mg against placebo in premenopausal women with confirmed symptomatic endometriosis. Enrollment was 60. The primary outcome was change from baseline in individual BBSS dysmenorrhea score, standardized to a 28-day period and assessed during and after the first on-drug cycle.

The registry reports the endpoint definition and safety counts, including no recorded serious adverse events or deaths in the listed groups. It does not report numerical primary endpoint results, the missing-data approach, or a multiplicity strategy. Therefore, the record describes the study framework and measurement but does not provide enough primary outcome information to assess the size or precision of the symptom comparison.