Trial · NCT04257929

A Phase 2 Study to Evaluate the Safety and Efficacy of Pitolisant in Patients With Prader-Willi Syndrome, Followed by an Open Label Extension

NCT04257929, Phase 2, Completed, Harmony Biosciences Management, Inc.; results first posted 2025-10-22

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. A Phase 2 Study to Evaluate the Safety and Efficacy of Pitolisant in Patients With Prader-Willi Syndrome, Followed by an Open Label Extension. Trials, record NCT04257929. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT04257929

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Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: A Phase 2 Study to Evaluate the Safety and Efficacy of Pitolisant in Patients With Prader-Willi Syndrome, Followed by an Open Label Extension
NCT number: NCT04257929
Status: Completed
Phases: Phase 2
Enrollment: 65 participants, actual
Lead sponsor: Harmony Biosciences Management, Inc.
Conditions: Prader-Willi Syndrome
Interventions: Pitolisant oral tablets, Placebo oral tablet
First posted: 2020-02-06
Last updated: 2026-05-12
Results first posted: 2025-10-22

Source ClinicalTrials.gov

Registered outcomes9

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Excessive Daytime Sleepiness	Baseline to Week 11	Change in Epworth Sleepiness Scale for Children and Adolescents (ESS-CHAD) (parent/caregiver version) score from Baseline to Week 11 for pitolisant compared with placebo. The score of the ESS-CHAD ranges from 0 to 24. A decrease in score represents an improvement in excessive daytime sleepiness.
Secondary	Excessive Daytime Sleepiness	Baseline to Week 11	Change in Caregiver Global Impression of Severity for Excessive Daytime Sleepiness. The Caregiver Global Impression of Severity for Excessive Daytime Sleepiness is a five-item scale that ranges from "not at all" to "very high likelihood." An assessment of being less likely to fall asleep represents an improvement in the caregiver's overall impression of the patient's excessive daytime sleepiness.
Secondary	Clinical Symptoms	Baseline to Week 11	Change in Clinical Global Impression of Severity of Overall Clinical Status. The Clinical Global Impression of Severity of Overall Clinical Status is a four-item scale that ranges from "normal" to "severely symptomatic." An assessment of less severe symptoms represents an improvement in the clinician's perception of the overall clinical status related to PWS.
Secondary	Behavior	Baseline to Week 11	Change in Aberrant Behavior Checklist, Second Edition. The Aberrant Behavior Checklist-Community, Second Edition, rates 58 specific symptoms on a four-item scale ranging from "not at all a problem" to "the problem is severe in degree." A decrease in score represents an improvement in the caregiver's impression in the patient's problematic behavior.
Secondary	Behavioral and Cognitive Rigidity	Baseline to Week 11	Change in Montefiore-Einstein Rigidity Scale - Prader-Willi Syndrome (MERS-R-PWS). The MERS-R-PWS is a clinician-rated, semi-structured interview conducted with both the patient with PWS and caregiver present. The MERS-R-PWS measures three domains of rigid behavior - behavior, cognitive, and protest. Within each domain, four items are rated on a scale ranging from 0 to 4. A decrease in score represents an improvement in rigid behavior.
Secondary	Psychomotor Function	Baseline to Week 11	Change in Cogstate Detection Test. The Cogstate Detection Test is a computerized test. Accuracy with a faster speed represents an improvement in psychomotor test performance.
Secondary	Attention	Baseline to Week 11	Change in Cogstate Identification Test. The Cogstate Identification Test is a computerized test. Accuracy with a faster speed represents an improvement in attention test performance.
Secondary	Working Memory	Baseline to Week 11	Change in Cogstate One Back Test. The Cogstate One Back Test is a computerized test. Accuracy with a faster speed represents a better working memory test performance.
Secondary	Caregiver Burden	Baseline to Week 11	Change in 22-Item Zarit Burden Interview. The Zarit Burden Interview is a self-reported questionnaire in which caregivers are asked to rate their experience on a five-item scale (0 = "never" and 4 = "nearly always") for 22 questions related to caregiver health and psychological well-being, finances, impact on social life, and relationship with the patient with PWS. A decrease in score represents an improvement in the caregiver's perceived burden.

Source ClinicalTrials.gov

Outcomes9

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Excessive Daytime Sleepiness	Baseline to Week 11	The efficacy population was the modified Intent-to-Treat (mITT) Population, which included all randomized patients who received at least 1 dose of study drug and had both a Baseline assessment and at least 1 post Baseline assessment for a given endpoint analysis during the Double-Blind Treatment Phase.	score on a scale	LEAST_SQUARES_MEAN
SECONDARY	Excessive Daytime Sleepiness	Baseline to Week 11
SECONDARY	Clinical Symptoms	Baseline to Week 11
SECONDARY	Behavior	Baseline to Week 11
SECONDARY	Behavioral and Cognitive Rigidity	Baseline to Week 11
SECONDARY	Psychomotor Function	Baseline to Week 11
SECONDARY	Attention	Baseline to Week 11
SECONDARY	Working Memory	Baseline to Week 11
SECONDARY	Caregiver Burden	Baseline to Week 11

Source ClinicalTrials.gov

Results by group3

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Value	Spread	Units
Excessive Daytime Sleepiness	Double-Blind Treatment Phase Lower Dose Pitolisant	-3.5	Standard Error 1.14	score on a scale
Excessive Daytime Sleepiness	Double-Blind Treatment Phase Higher Dose Pitolisant	-5.0	Standard Error 1.07	score on a scale
Excessive Daytime Sleepiness	Double-Blind Treatment Phase Placebo	-3.9	Standard Error 1.08	score on a scale

Source ClinicalTrials.gov

Participant flow9

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	Double-Blind Treatment Phase Lower Dose Pitolisant	20
Overall Study	STARTED	Double-Blind Treatment Phase Higher Dose Pitolisant	22
Overall Study	STARTED	Double-Blind Treatment Phase Placebo	23
Overall Study	COMPLETED	Double-Blind Treatment Phase Lower Dose Pitolisant	18
Overall Study	COMPLETED	Double-Blind Treatment Phase Higher Dose Pitolisant	21
Overall Study	COMPLETED	Double-Blind Treatment Phase Placebo	20
Overall Study	NOT COMPLETED	Double-Blind Treatment Phase Lower Dose Pitolisant	2
Overall Study	NOT COMPLETED	Double-Blind Treatment Phase Higher Dose Pitolisant	1
Overall Study	NOT COMPLETED	Double-Blind Treatment Phase Placebo	3

Source ClinicalTrials.gov

Adverse events27

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk
other	Anxiety	Psychiatric disorders	Double-Blind Treatment Phase Lower Dose Pitolisant	4	20
other	Anxiety	Psychiatric disorders	Double-Blind Treatment Phase Higher Dose Pitolisant	1	22
other	Anxiety	Psychiatric disorders	Double-Blind Treatment Phase Placebo	2	23
other	Irritability	Psychiatric disorders	Double-Blind Treatment Phase Lower Dose Pitolisant	4	20
other	Irritability	Psychiatric disorders	Double-Blind Treatment Phase Higher Dose Pitolisant	1	22
other	Irritability	Psychiatric disorders	Double-Blind Treatment Phase Placebo	1	23
other	Sleep disorder	Psychiatric disorders	Double-Blind Treatment Phase Lower Dose Pitolisant	2	20
other	Sleep disorder	Psychiatric disorders	Double-Blind Treatment Phase Higher Dose Pitolisant	0	22
other	Sleep disorder	Psychiatric disorders	Double-Blind Treatment Phase Placebo	0	23
other	Nasopharyngitis	Infections and infestations	Double-Blind Treatment Phase Lower Dose Pitolisant	2	20

1 to 10 of 27Source ClinicalTrials.gov

See all 27 adverse events

Adverse event totals9

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Double-Blind Treatment Phase Lower Dose Pitolisant	0	20
Total, all-cause mortality	Double-Blind Treatment Phase Higher Dose Pitolisant	0	22
Total, all-cause mortality	Double-Blind Treatment Phase Placebo	0	23
Total, other adverse events	Double-Blind Treatment Phase Lower Dose Pitolisant	13	20
Total, other adverse events	Double-Blind Treatment Phase Higher Dose Pitolisant	8	22
Total, other adverse events	Double-Blind Treatment Phase Placebo	9	23
Total, serious adverse events	Double-Blind Treatment Phase Lower Dose Pitolisant	0	20
Total, serious adverse events	Double-Blind Treatment Phase Higher Dose Pitolisant	0	22
Total, serious adverse events	Double-Blind Treatment Phase Placebo	1	23

Source ClinicalTrials.gov

Papers1

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as
40605372	DERIVED

Source PubMed

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests1

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

Test	Named as
1-Back Task	Secondary outcome

Source ConductCognition

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT04257929

GET https://conductscience.org/api/trials/v1/NCT04257929/events?page=2

API reference For AI assistants