A Phase 3 Efficacy and Safety Study of HBS-301 in Participants With Idiopathic Hypersomnia (IH)
A Phase 3, Randomized, Double-blind, Placebo-Controlled, Efficacy and Safety Study of HBS-301 in Participants With Idiopathic Hypersomnia (IH) Followed by an Open-label Extension
3 other identifiers
interventional
248
2 countries
42
Brief Summary
This is a Phase 3, multicenter, randomized, double-blind, parallel-group, placebo-controlled clinical study to assess the efficacy and safety of HBS-301 in adult participants (ages ≥18 years) with idiopathic hypersomnia (IH).
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P50-P75 for phase_3
Started Mar 2026
Typical duration for phase_3
42 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
Study Start
First participant enrolled
March 16, 2026
CompletedFirst Submitted
Initial submission to the registry
March 21, 2026
CompletedFirst Posted
Study publicly available on registry
March 30, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
October 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
October 1, 2028
September 14, 2026
September 1, 2026
1.5 years
March 21, 2026
September 11, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Change in severity of EDS as measured by the Epworth Sleepiness Scale (ESS)
The ESS is an 8-item, 4-point rating scale.
Baseline to the end of the Double-blind Treatment Period (8 weeks)
Secondary Outcomes (19)
Change in severity of IH symptoms as measured by the Idiopathic Hypersomnia Severity Scale (IHSS)
Baseline to the end of the Double-blind Treatment Period (8 weeks)
Change in sleep inertia as measured by the Sleep Inertia Questionnaire (SIQ)
Baseline to the end of the Double-blind Treatment Period (8 weeks)
Change in fatigue as measured by the Patient-Reported Outcomes Measurement Information System Fatigue Short Form 7a
Baseline to the end of the Double-blind Treatment Period (8 weeks)
Change in severity of EDS as measured by the Epworth Sleepiness Scale
Baseline through Week 1 and Week 2 of the Titration Period (1 week and 2 weeks)
Change in severity of IH symptoms as measured by the IHSS
Baseline through Week 1 and Week 2 of the Titration Period (1 week and 2 weeks)
- +14 more secondary outcomes
Study Arms (3)
Double-Blind Treatment Period HBS-301
EXPERIMENTALHBS-301 tablets administered once daily in the morning upon wakening
Double-blind Treatment Period Placebo
PLACEBO COMPARATORMatching placebo tablets administered once daily in the morning upon wakening
Open-label Extension Period HBS-301
EXPERIMENTALHBS-301 tablets administered once daily in the morning upon wakening
Interventions
HBS-301 tablet
Eligibility Criteria
You may qualify if:
- Has a current documented diagnosis of IH per the International Classification of Sleep Disorders, Third Edition (ICSD-3) or Text Revision (ICSD-3-TR) criteria with confirmatory polysomnogram (PSG) with multiple sleep latency test (MSLT; and if applicable, a 24-hour PSG report or an actigraphy report with sleep log) on file that led to the diagnosis and was completed within the last 10 years.
- Has EDS.
- Has moderate to very severe symptoms of IH.
- If taking a permitted chronic concomitant medication or supplement, including nonprohibited antidepressants or wake-promoting agents, must be on a stable dose for at least 3 months prior to Screening and agree to continue at that stable dose for the Double-blind Treatment Period of the study. As-needed use of any treatment that could affect daytime sleepiness (including but not limited to stimulants, modafinil, and armodafinil) used on an as-needed basis is not permitted.
You may not qualify if:
- Has hypersomnia due to another medical disorder.
- Has a history of pitolisant use within 5 half-lives prior to Screening.
- Has a primary diagnosis of psychiatric illness, including depression, that is not well controlled.
- Has a history of moderate or severe hepatic impairment.
- Has a body surface area (BSA)-corrected estimated glomerular filtration rate (eGFR) \<60 mL/min.
- Has a known history of long QT syndrome or any significant history of a serious abnormality of the electrocardiogram (ECG).
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (42)
Sleep Disorders Center of Alabama
Birmingham, Alabama, 35213, United States
Phoenix Medical Group LLC
Peoria, Arizona, 85381, United States
Stanford Center for Sleep Medicine
Redwood City, California, 94063, United States
Trial Site Solutions
San Ramon, California, 04583, United States
Santa Monica Clinical Trials
Santa Monica, California, 90404, United States
Alpine Clinical Research Center, Inc.
Boulder, Colorado, 80301, United States
Delta Waves LLC
Colorado Springs, Colorado, 80918, United States
PharmDev Research Institute, LLC
Miami, Florida, 33176, United States
Central Florida Pediatric Sleep Disorders Institute (Florida Pediatric Research Institute, LLC)
Winter Park, Florida, 32789, United States
NeuroTrials Research Inc.
Atlanta, Georgia, 30328, United States
Sleep Practitioners, LLC
Macon, Georgia, 31210, United States
Southeast Lung Associates Research
Rincon, Georgia, 31326, United States
Clinical Research Institute Stockbridge
Stockbridge, Georgia, 30281, United States
Fort Wayne Neurological Center
Fort Wayne, Indiana, 46804, United States
Revive Research Institute
Southfield, Michigan, 48975, United States
Clinical Neuropsychology Services
Sterling Heights, Michigan, 48314, United States
St. Luke's Hospital, Sleep Medicine and Research Center
Chesterfield, Missouri, 63017, United States
Clinical Research of Gastonia
Gastonia, North Carolina, 28054, United States
Stern Research Partners, LLC
Huntersville, North Carolina, 28078, United States
David Kudrow, MD
Morrisville, North Carolina, 27560, United States
Neuroscience Research Center, LLC
Canton, Ohio, 44718, United States
Intrepid Research
Cincinnati, Ohio, 45245, United States
Neurology Care
Ardmore, Oklahoma, 73401, United States
Abington Neurological Associates
Abington, Pennsylvania, 19001, United States
Suburban Research Associates
West Chester, Pennsylvania, 19380, United States
Berks Schuylkill Respiratory Specialists
Wyomissing, Pennsylvania, 19610, United States
Infinity Medical Research Inc.
East Providence, Rhode Island, 02914, United States
Lowcountry Lung and Critical Care, PA
Charleston, South Carolina, 29406, United States
Bogan Sleep Consultants, LLC
Columbia, South Carolina, 29201, United States
K2 Medical Research
Nashville, Tennessee, 37204, United States
Aayus Research
Austin, Texas, 78731, United States
Southwest Family Medicine Associates
Dallas, Texas, 75235, United States
Metroplex Pulmonary and Sleep Center
McKinney, Texas, 75069, United States
Sleep Therapy and Research Center
San Antonio, Texas, 30328, United States
HAS Research
San Antonio, Texas, 78240, United States
Tricoastal Narcolepsy and Sleep Disorders Center
Sugar Land, Texas, 77478, United States
TPMG Clinical Research
Williamsburg, Virginia, 23188, United States
Washington State University Sleep and Performance Center
Spokane, Washington, 99210, United States
West Virginia University
Morgantown, West Virginia, 26506, United States
University of Washington
Madison, Wisconsin, 53792, United States
AMNDX Inc
Markham, Ontario, M5S 3A3, Canada
Jodha Tishon Inc
Toronto, Ontario, M5S 3A3, Canada
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Study Officials
- STUDY DIRECTOR
David Seiden, MD
Harmony Biosciences Management, Inc.
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 3
- Allocation
- RANDOMIZED
- Masking
- TRIPLE
- Who Masked
- PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
March 21, 2026
First Posted
March 30, 2026
Study Start
March 16, 2026
Primary Completion (Estimated)
October 1, 2027
Study Completion (Estimated)
October 1, 2028
Last Updated
September 14, 2026
Record last verified: 2026-09
Data Sharing
- IPD Sharing
- Will not share