Recruiting
Phase 2
Phase 3

Cleminorexton

Sponsor:

Centessa Pharmaceuticals (UK) Limited

Code:

NCT07598708

Conditions

Narcolepsy Type 1

Narcolepsy Type 2

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Interventions

cleminorexton

Placebo

Study Details

Brief summary:

Narcolepsy Type 1 (NT1) and Narcolepsy Type 2 (NT2) are rare conditions that make people feel very sleepy during the day (often referred to as excessive daytime sleepiness \[EDS\]). People living with these conditions might find it hard to stay alert and pay attention when they are at school, working, driving, or performing other daily activities.

While all conditions result in feeling sleepy, there are some differences in other common symptoms:

  • NT1: People with NT1 often feel very tired during the day and experience cataplexy. Cataplexy is a sudden loss of muscle strength, which can cause someone to collapse or lose control of their muscles for a short time. This is often triggered by strong emotions, such as laughter or surprise. They may also have trouble sleeping well at night.
  • NT2: People with NT2 feel sleepy during the day, just like NT1, but they do not have cataplexy.

Orexin is a protein in the brain that helps coordinate a system that plays an important role in helping people to stay awake during the daytime. Cleminorexton is designed to mimic the action of orexin. The purpose of this study is to see how safe and tolerable cleminorexton is in NT1 and NT2 and learn about what the drug does to the body. Another goal of the study is to see if cleminorexton can help people with NT1 and NT2 feel less sleepy and make other symptoms better.

Conditions

Narcolepsy Type 1

Narcolepsy Type 2

Study ID

NCT07598708

Start date

May 29, 2026

Status verified date

Jul, 2026

Completion date

Dec 31, 2027

Anticipated

Primary completion date

Sep 30, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Key Inclusion Criteria:

  • 18-70 years of age
  • Body Mass Index (BMI) within the range ≥ 17.0 and ≤ 45 kg/m\^2 (inclusive)
  • Meets the diagnostic criteria of Narcolepsy Type 1 (NT1) or Type 2 (NT2) according to International Classification of Sleep Disorders, 3rd edition, Text Revision edition (ICSD-3-TR) criteria
  • Is willing and able to discontinue all medications used for the treatment of narcolepsy
  • Is willing and able to adhere to additional protocol requirements

Key Exclusion Criteria:

  • Medical disorder other than NT1 or NT2, that is associated with excessive daytime sleepiness (EDS)
  • Presence of significant cardiovascular, pulmonary, gastrointestinal, hepatic, renal, hematological, malignancy, endocrine, neurological or psychiatric disease

Study Design

Enrollment

222 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Group A - Narcolepsy Type 1 (Dose 1)

experimental: Group A - Narcolepsy Type 1 (Dose 2)

placebo comparator: Group A - Narcolepsy Type 1 (placebo)

experimental: Group B - Narcolepsy Type 2 (Dose 1)

experimental: Group B - Narcolepsy Type 2 (Dose 2)

placebo comparator: Group B - Narcolepsy Type 2 (placebo)

Interventions

cleminorexton

Oral cleminorexton capsule

Placebo

matching placebo capsule

Primary outcome measure

  • Change from baseline in mean sleep latency (average of the first 4 trials) on the Maintenance of Wakefulness Test (MWT) [ Time Frame: Baseline to week 12 ]

Central Contacts and Locations

Central contacts

Locations

Birmingham, Alabama

Recruiting

Birmingham, Alabama, United States, 35213

Colorado Springs, Colorado

Recruiting

Colorado Springs, Colorado, United States, 80918

Brandon, Florida

Recruiting

Brandon, Florida, United States, 33511

Miami, Florida

Recruiting

Miami, Florida, United States, 33155

Miami, Florida

Recruiting

Miami, Florida, United States, 33166

Miami, Florida

Recruiting

Miami, Florida, United States, 33176

Miami, Florida

Recruiting

Miami, Florida, United States, 33186

Miami Lakes, Florida

Recruiting

Miami Lakes, Florida, United States, 33014

Orlando, Florida

Recruiting

Orlando, Florida, United States, 32807

St. Petersburg, Florida

Recruiting

St. Petersburg, Florida, United States, 33707

Atlanta, Georgia

Recruiting

Atlanta, Georgia, United States, 30328

Rincon, Georgia

Recruiting

Rincon, Georgia, United States, 31326

Flowood Mississippi

Recruiting

Flowood, Mississippi, United States, 39232

Denver, North Carolina

Recruiting

Denver, North Carolina, United States, 28037

Huntersville, North Carolina

Recruiting

Huntersville, North Carolina, United States, 28078

Cincinnati, Ohio

Recruiting

Cincinnati, Ohio, United States, 45245

Dublin, Ohio

Recruiting

Dublin, Ohio, United States, 43017

Columbia, South Carolina

Recruiting

Columbia, South Carolina, United States, 29201

Austin, Texas

Recruiting

Austin, Texas, United States, 78731

Dallas, Texas

Recruiting

Dallas, Texas, United States, 75251

Houston, Texas

Recruiting

Houston, Texas, United States, 77070

San Antonio, Texas

Recruiting

San Antonio, Texas, United States, 78229

Sugar Land, Texas

Recruiting

Sugar Land, Texas, United States, 77478

More Information

Sponsor

Centessa Pharmaceuticals (UK) Limited

Last update posted

Oct 2, 2026

Last verified

Jul, 2026

Keywords

  • NT1
  • NT2
  • Excessive Daytime Sleepiness
  • Orexin Receptor 2 agonist
  • Central Disorders of Hypersomnia
  • Disorders of Excessive Somnolence
  • Dyssomnias
  • Nervous System Diseases
  • Mental Disorders
  • Hypersomnia
  • Hypersomnolence
  • Sleep Wake Disorders
  • Sleep Disorder
  • Sleep
  • Sleepiness
  • Cataplexy
  • Narcolepsy Type 1
  • Narcolepsy Type 2
  • Orexin
  • ORX750
  • Cleminorexton
  • Narcolepsy
  • SAPPHIRE

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-10. This information was provided to ClinicalTrials.gov by Centessa Pharmaceuticals (UK) Limited on 2026-10-02. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.