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Tourette Syndrome Phase 3 Binary Endpoint NCT03567291

Evaluation of Safety and Tolerability of Long-term TEV-50717 (Deutetrabenazine) for Treatment of Tourette Syndrome in Children and Adolescents: Complete Statistical Analysis

This analysis examines the registry record for a Phase 3 study of TEV-50717 in children and adolescents with Tourette syndrome. The primary outcome concerns treatment-emergent adverse events during a randomized withdrawal period, but a single comparison result is not reported in the registry record.

Trial start: 2018-05-25  ·  Enrollment: 228  ·  Sponsor: Teva Branded Pharmaceutical Products R&D, Inc.
Scope of this record

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 Evaluation of Safety and Tolerability of Long-term TEV-50717 (Deutetrabenazine) for Treatment of Tourette Syndrome in Children and Adolescents (NCT03567291), a randomized phase 3 study. The primary outcome is Number of Participants Reporting Treatment Emergent Adverse Events (AEs) in Part B (Period II).

228
Enrollment
Phase 3
n/a
Arms
In the primary outcome
n/a
Effect
No re-analysis shown
n/a
95% CI
See limitations
FeatureRegistry value
ClinicalTrials.gov identifierNCT03567291
PhasePhase 3
ConditionTourette Syndrome
AllocationRandomized
Design modelParallel
MaskingQuadruple
Enrollment228
Arms in the primary outcomen/a
Lead sponsorTeva Branded Pharmaceutical Products R&D, Inc.
Results postedYes

2. Clinical Question

Population

The study concerns children and adolescents with Tourette syndrome who had previously completed participation in a parent study. For the primary outcome, the population is more specific: participants who completed Period I, were randomized in Period II, and received any study drug during Part B, the randomized withdrawal period. The registry record lists an enrollment of 228, but that enrollment figure is not itself the primary-outcome analysis population.

Intervention

TEV-50717, also identified in the study title as deutetrabenazine, was administered during the study. Participants underwent dose titration in Part A; the starting dose and subsequent titration approach are described in the arm information. During the randomized withdrawal period, one arm continued to receive TEV-50717.

Comparator

Placebo was administered in the placebo arm during the two-week randomized withdrawal period. The registry describes the study as otherwise open-label, with this withdrawal period double-blind and placebo-controlled. The arm descriptions do not establish the number of participants assigned to each randomized arm.

Primary question

The primary outcome asks how many participants reported treatment-emergent adverse events during Part B, Period II, from Week 28 to Week 30. An adverse event could be an untoward medical occurrence that developed or worsened during the study and did not need to be caused by study treatment. The registry record does not report a single arm-level result for this outcome, so it does not support a numerical comparison between continued TEV-50717 and placebo for the specified period.

3. Trial Design

This was a Phase 3, randomized, parallel-group study of TEV-50717 in children and adolescents with Tourette syndrome. The registry lists an enrollment of 228 and identifies Teva Branded Pharmaceutical Products R&D, Inc. as the sponsor. The study started on 2018-05-25, had a primary completion date of 2020-05-15, and is listed as terminated.

The overall study is described as open-label and single-arm, with a double-blind, placebo-controlled, randomized drug withdrawal period embedded within it. The withdrawal period lasted two weeks. The brief study description also refers to a three-week blinded maintenance or re-titration period, followed by a maintenance period. The registry lists quadruple masking, while the study description distinguishes the open-label portions from the blinded randomized withdrawal period. These descriptions refer to different features of the study and should not be taken to mean that every phase had the same masking arrangement.

In Part A, participants underwent TEV-50717 dose titration. The arm description states that participants received 6 mg with food on the evening of day 1; subsequent titration and maximum dose depended on body weight and CYP2D6 impairment status from the parent study. During Part B, the randomized withdrawal period, participants were assigned to TEV-50717 or placebo. The placebo arm description specifies placebo only during that period.

The primary outcome focuses on treatment-emergent adverse events in Part B, Period II, over Weeks 28 to 30. The outcome population is defined as participants who completed Period I, were randomized in Period II, and received any study drug in the randomized withdrawal period. The allocation ratio, randomization procedure, detailed masking procedures, and reasons for termination are not reported in the registry record.

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: Period I (Part A) included a 28-week open-label period with a 7-week titration period followed by a maintenance period. Period II (Part B) included a two-week randomized drug withdrawal period (Weeks 28-30) in which participants were administered their current TEV50717 dose or placebo. Participants were re-titrated to TEV-50717 from Weeks 31-34. In Period III (Part A resumed), participants continued their open-label maintenance dose of TEV50717.

Period I

StageTEV-50717Randomized TEV-50717Randomized PlaceboTEV-50717 Re-titration and Maintenance
STARTED228000
Safety Set227000
Intent to Treat Set228000
COMPLETED137000
NOT COMPLETED91000

Reasons for not completing this period:

ReasonTEV-50717Randomized TEV-50717Randomized PlaceboTEV-50717 Re-titration and Maintenance
Adverse Event14000
Protocol Violation1000
Withdrawal by Subject23000
Lost to Follow-up2000
Terminated by sponsor44000
Missing or unknown7000

Period II

StageTEV-50717Randomized TEV-50717Randomized PlaceboTEV-50717 Re-titration and Maintenance
STARTED091460
COMPLETED088450
NOT COMPLETED0310

Reasons for not completing this period:

ReasonTEV-50717Randomized TEV-50717Randomized PlaceboTEV-50717 Re-titration and Maintenance
Adverse Event0100
Missing or unknown0210

Period III

StageTEV-50717Randomized TEV-50717Randomized PlaceboTEV-50717 Re-titration and Maintenance
STARTED000133
COMPLETED00048
NOT COMPLETED00085

Reasons for not completing this period:

ReasonTEV-50717Randomized TEV-50717Randomized PlaceboTEV-50717 Re-titration and Maintenance
Adverse Event0004
Withdrawal by Subject0004
Lost to Follow-up0001
Terminated by sponsor00068
Missing or unknown0008

Analysis population for the primary outcome, as defined in the registry: Safety analysis set included all participants who received at least 1 dose of 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: Intent-to-treat (ITT) analysis set included all enrolled participants.

CharacteristicUnitAll Participants
Participants analysed228
Age, ContinuousYears12 (SD 2.59)
Sex/Gender, Customized: Participants – MaleParticipants182
Sex/Gender, Customized: Participants – FemaleParticipants45
Sex/Gender, Customized: Participants – UnknownParticipants1
Ethnicity (NIH/OMB): Hispanic or LatinoParticipants38
Ethnicity (NIH/OMB): Not Hispanic or LatinoParticipants186
Ethnicity (NIH/OMB): Unknown or Not ReportedParticipants4
Race/Ethnicity, Customized: WhiteParticipants197
Race/Ethnicity, Customized: BlackParticipants4
Race/Ethnicity, Customized: AsianParticipants7
Race/Ethnicity, Customized: Native AmericanParticipants5
Race/Ethnicity, Customized: OtherParticipants15

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Reporting Treatment Emergent Adverse Events (AEs) in Part B (Period II), measured over Weeks 28 to 30.

ElementRegistry entry
Result typeNumber
Measure of spreadnot applicable
UnitParticipants
Endpoint classificationBinary Endpoint

The primary outcome is the number of participants reporting treatment-emergent adverse events during Part B, Period II, with the timeframe listed as Weeks 28 to 30. It is a participant-count outcome: the focus is on whether participants reported an event, rather than on the total number of events experienced by each participant or the severity of every event.

The registry definition includes an untoward medical occurrence that develops or worsens during the study. An event does not have to be caused by study treatment to qualify. Clinically significant changes, including changes in vital signs or laboratory values, are also included. The investigator determined whether an event was related to treatment. Serious adverse events have a separate definition that includes outcomes such as death, life-threatening events, inpatient hospitalization or its prolongation, persistent or significant disability, congenital anomaly or birth defect, and important medical events requiring intervention to prevent serious outcomes.

Counting participants with events is a way to describe how many people experienced at least one qualifying event in the specified period. It can provide a safety summary, but by itself it does not describe the number of events per person, the timing or duration of events, or whether the event was judged treatment-related. The registry record does not report a single comparative result for the primary outcome. It also directs readers to the reported adverse-event information for summaries of other non-serious events and serious events regardless of causality.

7. Why No Re-analysis Is Shown

Reported as posted, not recalculated. Primary outcome has several categories or time points; not reduced to one comparison. A result is recalculated only when the posted data support a clean two-arm comparison, so no result is shown beyond what the sponsor posted.

8. Statistical Interpretation

Clinical Biostats interpretation

The study’s primary outcome is a count of participants reporting treatment-emergent adverse events during the randomized withdrawal period, not a measure of tic severity or quality of life. Although the record describes the intended outcome and its timeframe, it does not provide an arm-by-arm count or a single comparison result for that outcome. The primary outcome has several categories or time points and is not reduced to one comparison in the registry record. Consequently, a numerical contrast between participants receiving TEV-50717 and those receiving placebo cannot be interpreted from the primary-outcome information available in the record.

The record does give an overall adverse-event summary for a total group of 227 participants: 2 participants were affected by serious adverse events, 108 by other adverse events, and 0 deaths were reported. The listed serious adverse-event terms are abdominal pain upper and self-injurious ideation, each reported as 0.4%. These figures are descriptive totals. They should not be treated as the primary outcome’s randomized comparison, since the record does not identify them as arm-specific results for Weeks 28 to 30.

Several details necessary for judging a comparative result are absent. The record does not report the number of participants with the primary outcome in each randomized arm, an estimated between-arm difference, a confidence interval, or a p-value. It also does not report the number randomized to each arm or a clear account of missing primary-outcome observations. Without those details, readers cannot assess the size or precision of an arm-level difference or determine whether the observed participant counts, if any, would be compatible with a range of possible effects.

In general, a confidence interval expresses the uncertainty around an estimated effect under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, but neither an interval nor a significance test can be interpreted when the corresponding estimate is not reported. A p-value, if reported, would address compatibility with a specified null model; it would not by itself communicate the size or practical importance of an effect. No such inferential result for the primary endpoint is reported in the registry record.

The study also lists secondary outcomes involving tic severity, global impressions, quality of life, and change in tic score during randomized withdrawal. These outcomes provide context for the broader study aims, but their presence does not fill the gap in the primary outcome’s comparative reporting. No secondary-outcome results are included in the registry record for this analysis. Thus the record supports a description of the study structure and the reported overall adverse-event counts, but not a conclusion about a randomized difference in the primary outcome or the secondary outcomes.

9. Statistical Methods Explained

The primary endpoint is a binary participant-level outcome: a participant either reported at least one qualifying treatment-emergent adverse event during the specified period or did not. For this kind of outcome, the central descriptive information is usually the number of participants with an event and the number assessed in each group. A comparative analysis may then express the difference or another contrast between groups, together with an uncertainty measure. The registry record does not report a single arm-level comparison for this endpoint, so those comparative quantities are not available for interpretation.

What does a participant count represent?

A count of participants with events answers a different question from a count of event episodes. If one participant has more than one event, a participant-based summary still counts that person once for the outcome, whereas an event-based summary may count multiple episodes. The stated primary outcome is the number of participants reporting events. The registry definition also allows events that are not considered caused by study treatment, so this endpoint is not limited to events judged related to the drug.

For a randomized comparison, group sizes matter because the same event count can convey different information when the numbers assessed differ. A percentage can make group summaries easier to compare, but percentages alone do not show uncertainty and can obscure small denominators. The registry’s primary-outcome description supplies neither arm-level event counts nor denominators for each arm. The overall adverse-event summary of 227 participants is not a substitute for those randomized group-specific quantities.

Why does the randomized withdrawal design matter?

In general, randomization is used to create groups whose outcomes can be compared without assigning treatment according to participant characteristics. In a randomized withdrawal study, participants enter a randomized period after an earlier study phase, and the contrast concerns what happens during that withdrawal period under the assigned regimens. Such a design answers a question about the randomized period and its selected population; it does not automatically represent all people with the condition or every stage of treatment.

Here, the primary-outcome population is defined by completing Period I, being randomized in Period II, and receiving study drug during Part B. This is narrower than the overall enrollment of 228. The criteria used to enter the parent studies, the numbers reaching each later phase, and the number assigned to each randomized arm are not reported in the registry record. Those details would help readers understand how the analyzed population relates to the initial enrollment.

How should uncertainty be read?

In general, an estimate describes the result in the observed study participants, while a confidence interval describes the statistical uncertainty around that estimate under a chosen analysis. An interval that includes values on both sides of no difference may be consistent with multiple possible effects; an interval that excludes no difference can still be wide enough to leave substantial uncertainty about the effect’s size. Statistical significance and practical importance are distinct questions. The registry record does not report an effect estimate, confidence interval, or p-value for the primary outcome, so none can be evaluated.

The record lists one analysis and 13 outcome measures, but it does not describe the analysis model, the method for constructing confidence intervals, or the handling of repeated or multiple outcome tests. A general statistical issue in count data is over-dispersion: the observed variability may be greater than a model assumes. This matters when an analysis models event counts, because underestimated variability can make uncertainty appear too small. The primary outcome is a count of participants with an event, rather than a total event count, and the registry record does not state that an over-dispersion model was used.

What do the planning assumptions mean?

The planning illustrations are described as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not observed outcomes and not observed power. In general, sample-size planning estimates how many participants might be needed to detect a specified effect under stated assumptions. It does not show the probability that the completed study detected an effect, nor does it establish that the assumptions were met.

The registry record does not report the underlying planning values or the effect estimates needed to interpret those illustrations in detail. No new sample-size calculation is made from the overall enrollment. Enrollment is not the same as the number analyzed for the primary outcome, and the record does not give the randomized arm sizes or the number with complete outcome data.

Finally, an analysis population should be distinguished from the set of all enrolled participants. The primary outcome population is explicitly restricted to participants who completed Period I, entered randomization in Period II, and received study drug during the withdrawal period. Whether participants were analyzed according to randomized assignment, whether any participants were excluded after randomization, and how missing outcome data were handled are not reported in the registry record. These choices can affect interpretation, especially when the number analyzed differs from the number randomized.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 13 outcome measures, including the primary adverse-event outcome and secondary measures of tic severity, global impressions, and quality of life. Multiple outcomes can create a multiplicity issue: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. In general, a statistical plan may address this through a prespecified hierarchy, an adjustment procedure, or a distinction between confirmatory and exploratory outcomes. The registry record does not report a multiplicity strategy, an ordering of tests, or which outcomes were intended to support confirmatory claims.

The primary outcome itself has several categories or time points and is not reduced to a single comparison in the registry record. It is therefore not possible to identify one reported primary contrast and assess its uncertainty or any adjustment applied to it. The record lists one analysis, but the analysis method and any relationship between that analysis and the multiple outcomes are not reported in the registry record.

Missing data can also affect interpretation. In general, missing outcome observations reduce the information available and may introduce bias if the probability of missingness is related to participant characteristics or outcomes. The record defines the primary-outcome population but does not report the number with missing data, reasons for missingness, imputation methods, or sensitivity analyses. It also does not report whether participants who stopped treatment or did not complete the randomized period remained in an analysis population.

The population definition matters because it requires completion of Period I, randomization in Period II, and receipt of any study drug during Part B. The record does not report the numbers meeting each criterion or the randomized arm counts. Without those details, readers cannot trace participant flow from enrollment to the primary-outcome analysis or assess how exclusions and missingness may have influenced the reported summaries.

11. Safety Results

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

ArmParticipants with serious adverse eventsParticipants at riskPercentage
Total22270.9%

Deaths

ArmDeaths (participants affected of at risk)
Total0 of 227

Other (non-serious) adverse events

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

ArmParticipants affected of at risk
Total108 of 227

Most frequent serious adverse event terms

Event termOrgan systemTotal
Abdominal pain upperGastrointestinal disorders1 of 227
Self-injurious ideationPsychiatric disorders1 of 227

Most frequent non-serious adverse event terms

Event termOrgan systemTotal
HeadacheNervous system disorders30 of 227
SomnolenceNervous system disorders28 of 227
NasopharyngitisInfections and infestations23 of 227
Weight increasedInvestigations22 of 227
AnxietyPsychiatric disorders17 of 227
VomitingGastrointestinal disorders15 of 227
TicPsychiatric disorders15 of 227
PyrexiaGeneral disorders13 of 227

Serious events with the highest arm-level rate: abdominal pain upper (0.4%), self-injurious ideation (0.4%).

Do not overextend the safety comparison. Serious-adverse-event counts are safety observations, not efficacy outcomes, and should not be combined with the primary result into a single benefit-risk number.

The registry’s overall adverse-event summary lists 227 participants at risk for both serious and other adverse events. It reports 2 participants affected by serious adverse events, 108 affected by other adverse events, and 0 deaths. These are participant counts, not necessarily counts of all event episodes. One participant may experience more than one event, so the figures should not be read as a complete tally of individual episodes.

The serious adverse-event terms listed are abdominal pain upper and self-injurious ideation, each reported as 0.4%. The record does not specify in this summary whether these terms occurred in separate participants or how each term relates to the participant-level serious-event count. The listed percentage should be quoted as reported rather than used to infer additional counts.

Seriousness and treatment relationship are different classifications. The registry definition identifies serious events by their outcomes or medical significance, while the investigator determined whether an event was related to treatment. The overall summary includes serious events regardless of causality, and the listed totals are not presented as a comparison between the randomized arms. They also are not identified as a Week 28 to Week 30 result for the primary outcome. The registry record does not report arm-specific serious-event counts in the information available for this analysis.

Accordingly, these figures describe the reported overall safety summary only. They do not by themselves establish the cause of an event, compare the safety of the randomized regimens, or characterize every potential risk.

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

The registry record establishes that this Phase 3 study included an open-label treatment period and a randomized withdrawal period comparing TEV-50717 with placebo. It identifies a primary safety outcome based on participants reporting treatment-emergent adverse events during Weeks 28 to 30. The record also provides overall adverse-event counts for 227 participants, including 2 participants affected by serious adverse events, 108 affected by other adverse events, and 0 deaths.

Those descriptive details do not amount to a comparative result for the primary outcome. The record does not report the number of participants with treatment-emergent adverse events in each randomized arm or a single estimate comparing the arms. It also does not report a confidence interval or p-value for that outcome. Without those results, readers cannot assess the direction, size, or precision of a randomized difference during the withdrawal period.

The overall adverse-event figures should not be used as a substitute for the specified primary outcome comparison. The summary does not identify its counts as arm-specific or as limited to Weeks 28 to 30. Nor does the total enrollment of 228 indicate how many participants were randomized or analyzed in each arm. The serious adverse-event terms and percentages describe reported terms but do not establish causation.

The study’s listed secondary outcomes concern changes in tic severity, clinical and patient global impressions, and quality of life. Their inclusion indicates the range of outcomes the study intended to assess, but the registry entries for this analysis do not contain their results. Accordingly, no conclusion about those measures follows from the information.

In general, absence of a reported comparison is not evidence that the groups were identical, nor is it evidence that one regimen was better or worse. It means that the registry record, as represented in this analysis, does not supply the numerical result needed to answer that comparative question. Any interpretation should remain limited to the design and descriptive safety information that the record does report.

13. Why This Trial Matters Statistically

This study is statistically notable because its primary safety question sits within a longer study that was otherwise open-label and single-arm. The randomized withdrawal period creates a controlled comparison for a defined part of the study, but that comparison applies to the participants who reached the randomized period and received study drug. The registry defines that population separately from the initial enrollment, which is important when considering how broadly the results might apply.

The timing and structure also matter. The primary outcome concerns treatment-emergent adverse events during Part B, Period II, over Weeks 28 to 30, while other outcomes address changes in tic scores, global impressions, and quality of life. Distinguishing the randomized period from the broader study prevents overall safety summaries from being mistaken for arm-specific randomized evidence or for results across the full treatment period.

There is also a useful distinction between describing events and estimating a treatment contrast. Overall counts can summarize how many participants were affected in the reported group, but a comparative question requires arm-specific counts and denominators, plus an estimate of uncertainty. The record reports overall safety figures but does not report one primary comparison. This illustrates why a defined endpoint and a completed analysis are not the same as a reported result that supports comparison.

The registry lists 13 outcome measures and a single analysis, yet does not describe a multiplicity strategy or the analysis method. Those omissions matter for readers evaluating how results across outcomes were selected and interpreted. The record’s planning assumptions also demonstrate that sample-size illustrations depend on specified choices; such calculations are not a substitute for observed estimates and uncertainty from the completed trial.

14. Limitations

The most important limitation for interpretation is that the registry record does not report a single comparative result for the primary outcome. There are no arm-specific counts, denominators, effect estimate, confidence interval, or p-value for treatment-emergent adverse events during Weeks 28 to 30. The overall adverse-event summary cannot resolve this because it is not identified as the randomized comparison for that timeframe.

The participant flow is also incomplete in the registry information. Although enrollment is listed as 228, the number entering Part B, the number randomized to each arm, and the number included in the primary-outcome population are not reported in the registry record. Reasons for study termination and the number of participants who discontinued or had missing outcome data are also not reported in the registry record.

Important analysis details are absent. The statistical model, the method for handling missing observations, the analysis population beyond the stated primary-outcome eligibility definition, and sensitivity analyses are not reported in the registry record. The record lists multiple outcome measures but does not report how multiplicity was handled. The allocation ratio, randomization procedure, and practical details of masking are also not reported in the registry record.

Finally, the study’s randomized withdrawal comparison applies to the population reaching that period, rather than automatically to everyone initially enrolled. The available overall adverse-event counts do not provide enough detail to assess differences by arm, timing, severity, or treatment relationship. These limitations constrain what can be inferred from the registry information; they do not establish that any unreported result had a particular direction.

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18. Record Summary

The registry record describes NCT03567291, a Phase 3 study of TEV-50717 in children and adolescents with Tourette syndrome. The study was randomized and parallel-group, with a longer open-label study structure that included a two-week, double-blind, placebo-controlled randomized withdrawal period. Enrollment was 228, and the record lists the study as terminated.

The primary outcome was the number of participants reporting treatment-emergent adverse events during Part B, Period II, from Weeks 28 to 30. The record does not provide a single randomized comparison result for that endpoint. Its overall adverse-event summary lists 227 participants at risk, 2 affected by serious adverse events, 108 by other adverse events, and 0 deaths. The serious-event terms abdominal pain upper and self-injurious ideation are each reported as 0.4%.

The record lists 13 outcome measures, but detailed analysis methods, arm-level primary results, missing-data handling, and multiplicity procedures are not reported in the registry record. The available information supports description of the study design and overall safety summary, but not a numerical interpretation of the primary randomized contrast.

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