A Phase 3 Study to Evaluate the Efficacy and Safety of Samelisant in Patients With Narcolepsy

NCT07540364 | Not Yet Recruiting Phase 3 DMC FDA Drug

• 1 other identifier: CTP3S13031H3
• Study Type: interventional
• Target: 240
• Locations: 0 countries
• Sites: N/A

Brief Summary

The primary objective of this study is to evaluate the effect of Samelisant on excessive daytime sleepiness (EDS) after 12 weeks of treatment. In addition, the study aims to assess its effectiveness in influencing the weekly frequency of cataplexy episodes (sudden bouts of muscle weakness) that occur while the individual remains conscious. Other objectives include examining the impact of Samelisant on attention and alertness, overall quality of life, the spectrum of narcolepsy symptoms, and daily functioning, as well as evaluating its safety profile.

Conditions

Narcolepsy

Keywords

Samelisant; SUVN-G3031; Excessive Daytime Sleepiness; Narcolepsy; Cataplexy

Outcome Measures

Primary Outcomes (1)

• Change from Baseline in total Epworth Sleepiness Scale (ESS) score at Week 12

  The ESS is a subjective measure of daytime sleepiness. The participant rates on a 4-point Likert scale how likely it is that he/she would doze in 8 different situations. Scoring of the answers is 0 to 3, with 0 being "would never doze" and 3 being "high chance of dozing". The total ESS score ranges from 0 to 24, with higher scores indicating greater daytime sleepiness. A decrease from baseline in ESS score represents improvement.

  Baseline to Week 12

Secondary Outcomes (4)

• Change from Baseline for Maintenance of Wakefulness Test (MWT) score at Week 12

  Baseline to Week 12

• Change from Baseline in the Clinical Global Impression of Severity of Illness (CGI-S) score as related to excessive daytime sleepiness (EDS) at Week 12

  Baseline to Week 12

• Change from Baseline in Weekly Cataplexy Rate (WCR) for Narcolepsy Type 1 (NT1) at Week 12

  Baseline to Week 12

• Change from Baseline in Narcolepsy Severity Scale for Clinical Trials (NSS-CT) score for Narcolepsy Type 1 (NT1) at Week 12

  Baseline to Week 12

Study Arms (2)

Samelisant Tablets

ACTIVE COMPARATOR

Drug: Samelisant

Placebo Tablets

PLACEBO COMPARATOR

Drug: Placebo

Interventions

Samelisant DRUG

Tablet dosage form, once a day

Also known as: SUVN-G3031

Samelisant Tablets

Placebo DRUG

Matching placebo tablets, once a day

Placebo Tablets

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Body mass index ranging from 18 to 45 kg/m2 (both inclusive).
• Narcolepsy with or without cataplexy (Narcolepsy Type 1 \[NT1\] or Narcolepsy Type 2 \[NT2\]) based on the International Classification of Sleep Disorders 3-TR/ Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) criteria for the diagnosis of narcolepsy.
• For NT1 only, current continuing presence of cataplexy as defined by participant report for the last 3 months and have average of ≥4 weekly cataplexy events during the last 2 weeks of the washout period.
• At the screening Visit and the Baseline Visit, participants who are not on treatment for EDS must have ESS scores ≥12 (as assessed with a look-back period of 1 week).
• A mean MWT time of \<12 minutes across the first 4 sessions at Baseline.
• Willingness to complete the study protocol with full compliance with procedures and sign an informed consent form.
• Able to show compliance with sleep diary entries for at least 5 times/week in the final 2 weeks of the screening Period (non-compliant participants will not be included).

You may not qualify if:

• Median habitual wake-up time after 9 am as assessed by sleep diary, habitual sleep time of \<6 h and median habitual bedtime past 1 am, as determined by sleep diary entries.
• Use of any investigational therapy within the 30-day period (or 5 half-lives, whichever is longer) prior to enrollment.
• History of (within past 3 months) or current substance use disorder involving illicit drugs, alcohol, or marijuana, as per DSM-5-TR criteria. Alcohol and/or recreational drugs use within 24 hours of study visits is strictly prohibited.
• Excessive caffeine (defined as \>600 mg/day) use at least 1 week prior to Baseline assessments and during the study.
• Nicotine dependence that affects sleep (eg, a participant who routinely awakens at night to smoke).
• If receiving stimulants, modafinil, oxybates, pitolisant, solriamfetol, bupropion or other treatments for narcolepsy, and unwilling or unable to complete weaning 2 weeks prior to Baseline visit (Day 1)
• Clinically significant ECG abnormalities. Participants are excluded with a screening ECG Fridericia's correction of QT (QTcF) interval ≥450 msec for men and ≥470 msec for women obtained after 5-minute rest in a supine position using a digital ECG.
• Concurrent use of hypnotics, tranquilizers, centrally acting H1 receptor antagonists, benzodiazepines, anticonvulsants, or clonidine, tricyclic antidepressants that have H1-antihistamine properties (clomipramine, protriptyline).
• Adjunctive pharmacotherapy directed against cataplexy (including but not limited to venlafaxine, fluoxetine, and gamma hydroxybutyrate) is prohibited.
• An occupation requiring variable shift work, variable wake times, night shifts, frequent overnight travel or expected overnight travel across \> 3 time zones during the study which disrupts sleep patterns and working remotely leading to inconsistent sleep duration.

Sponsors & Collaborators

• Suven Life Sciences Limited: lead

MeSH Terms

Conditions

Narcolepsy; Disorders of Excessive Somnolence; Cataplexy

Interventions

samelisant

Condition Hierarchy (Ancestors)

Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Nervous System Diseases; Mental Disorders

Central Study Contacts

Study Contact

CONTACT

+9140 2319 3956; narcolepsy@suven.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 13, 2026
• First Posted: April 20, 2026
• Study Start (Estimated): June 19, 2026
• Primary Completion (Estimated): November 19, 2027
• Study Completion (Estimated): December 19, 2027
• Last Updated: April 20, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share