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Efficacy and Safety of E2086 in Adults with Narcolepsy: A Randomized, Double‑Blind, Placebo‑Controlled Trial

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What is this trial about?

A plain-language summary of the goals, design and what participants do

Narcolepsy is a rare sleep disorder that causes excessive daytime sleepiness, meaning a strong urge to fall asleep during normal daily activities, and may also lead to sudden loss of muscle tone called cataplexy. The trial evaluates an oral tablet named E2086, compared with a matching placebo, to determine whether it can lessen these symptoms.

The purpose of the study is to find the optimal dose of E2086 for reducing excessive daytime sleepiness in adults with narcolepsy. Participants are randomly assigned to receive either the active tablet or placebo for several weeks. Sleepiness is measured by the time it takes to fall asleep during a series of four MWT (maintenance of wakefulness tests), reported as MSL (mean sleep latency), and by a questionnaire called the ESS that asks about the chance of dozing in everyday situations. Safety monitoring includes blood pressure checks with a device that measures pressure over 24 hours (ABPM), heart rhythm recording with a 12‑lead ECG, laboratory blood tests, and a brief interview to assess suicidal thoughts using the C‑SSRS (Columbia‑Suicide Severity Rating Scale). The study includes people with both type 1 (NT1) and type 2 (NT2) forms of narcolepsy and lasts about four weeks, with regular clinic visits for assessments.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessment

    On the first day after joining the trial you will complete a questionnaire that measures daytime sleepiness called the epworth sleepiness scale.

    You will undergo a series of four maintenance of wakefulness tests to determine your mean sleep latency, which is the average time it takes you to fall asleep.

    Blood samples will be taken to measure laboratory values, and vital signs such as blood pressure will be recorded.

    An electrocardiogram (ecg) will be performed to assess heart rhythm.

  2. Step 2

    Randomization and start of medication

    After baseline assessments you will be randomly assigned to receive either the study drug e2086 or a matching placebo tablet that looks the same.

    The tablet is taken orally once daily; the listed dose is 0 mg of the active substance per tablet.

    The medication will be taken for a total period of four weeks.

  3. Step 3

    Weekly safety visits

    During weeks 1, 2 and 3 you will attend a weekly visit at the study site.

    At each visit you will report any adverse events (new or worsening symptoms), and blood pressure will be measured again.

    Additional blood samples may be collected to monitor laboratory values, and an ecg may be repeated if needed.

    The epworth sleepiness scale may be completed again to track changes in daytime sleepiness.

  4. Step 4

    Final assessment at week 4

    At the end of week 4 you will repeat the four maintenance of wakefulness tests to reassess mean sleep latency.

    The epworth sleepiness scale will be completed again to evaluate any change in sleepiness.

    Blood samples, vital signs, and an ecg will be performed to assess safety.

    The frequency of cataplexy episodes (sudden loss of muscle tone) will be recorded for participants who experience this symptom.

  5. Step 5

    Study completion

    After the final assessment you will stop taking the study tablets.

    The study team will provide information on any further follow‑up that may be required.

Who can join the trial?

10 criteria

  • Be at least 18 years old at the time you sign the consent form.
  • Have narcolepsy type 1 (NT1) diagnosed within the past 10 years, confirmed by either a sleep study called polysomnography and a test called the Multiple Sleep Latency Test (MSLT), or by a low level of the brain protein orexin‑A (≤110 pg/mL) in spinal fluid.
  • If you have NT1, experience at least four episodes of cataplexy per week (sudden loss of muscle tone) recorded over a minimum of two weeks in a diary.
  • Have narcolepsy type 2 (NT2) diagnosed within the past 10 years, confirmed by polysomnography and the MSLT together with your medical history.
  • Score 10 or higher on the Epworth Sleepiness Scale (ESS), a questionnaire that measures how likely you are to fall asleep in everyday situations.
  • Usually try to go to bed between 10:00 pm and 1:00 am, as recorded in your sleep diary.
  • Usually get out of bed between 5:00 am and 10:00 am, as recorded in your diary.
  • Usually spend 7 to 9 hours in bed each night, based on the sleep portion of your diary.
  • Complete at least 80 % of the diary entries during the screening period.
  • Have a body mass index (BMI) between 18 and less than 35 kg/m² at screening, a measure of weight relative to height.

Who cannot join the trial?

35 criteria

  • Women who are pregnant or breastfeeding (a positive beta‑hCG pregnancy test shows pregnancy).
  • Women who could become pregnant and are not using a highly effective birth‑control method, or who do not agree to use birth control during the study and for 28 days after stopping the study drug (contraception methods include IUD, implant, hormonal pills, etc.).
  • Any serious illness that needs medical treatment within 8 weeks before the first dose, or any infection that needs treatment within 4 weeks.
  • Any other disease that might affect the study results, such as mental‑health problems or disorders of the stomach, liver, kidneys, lungs, hormones, blood, nerves, or heart.
  • Past surgery that could change how the study drug is processed, such as removal of the liver, kidney, or parts of the digestive system, or a birth defect that affects metabolism.
  • Severe kidney problems (estimated glomerular filtration rate eGFR < 30 mL/min) or any abnormal symptom or organ problem found in medical history, exam, vital signs, ECG, or lab tests that requires treatment.
  • A heart‑rhythm measurement called QTc longer than 450 milliseconds on an ECG (electrocardiogram).
  • Blood pressure that is consistently high (systolic > 130 mmHg or diastolic > 85 mmHg) or low (systolic < 100 mmHg or diastolic < 50 mmHg) measured on several occasions.
  • Heart rate that is consistently below 50 beats per minute or above 100 beats per minute measured on several occasions.
  • Any lifetime history of suicidal behavior, as identified by the C‑SSRS questionnaire (a tool that asks about suicide thoughts and actions).
  • Current unstable mental illness, an active major depressive episode now, or a major depressive episode in the past 6 months.
  • Suicidal thoughts with a plan or intent within 6 months (answering “yes” to certain questions on the C‑SSRS).
  • Psychotic disorders or unstable mood disorders where antipsychotic medication was used within the past 2 years.
  • Allergy (hypersensitivity) to the study drug or any of its inactive ingredients.
  • Use of herbal products that contain St. John’s Wort within a time period equal to five times the drug’s half‑life before the first dose.
  • Any medical condition that the investigator believes would make it unsafe to finish the study.
  • Planned surgery that requires general, spinal, or epidural anesthesia during the study period (local anesthesia only may be allowed).
  • Known to be positive for human immunodeficiency virus (HIV).
  • Acute infection with Epstein‑Barr virus (EBV) shown by a positive IgM antibody test at the start of the study.
  • Known to be positive for hepatitis B or hepatitis C with detectable virus within 6 months before the first dose (resolved hepatitis C may be allowed with a negative test).
  • Starting a statin medication, changing to a different statin, or increasing the statin dose within 6 months before the study.
  • Diagnosed moderate to severe obstructive sleep apnea (OSA).
  • Currently using treatment for OSA such as a CPAP machine, hypoglossal nerve stimulator, oral device, or other therapy.
  • Having symptomatic restless legs syndrome.
  • Having an apnea‑hypopnea index ≥ 15 on a sleep study (screening polysomnography).
  • Use of anticataplectic medicines (including some antidepressants) within five half‑lives before screening.
  • Use of stimulant medicines (prescription or over‑the‑counter) within five half‑lives before screening and until after the final visit. Examples include pseudoephedrine, methylphenidate, amphetamines, modafinil, armodafinil, sodium oxybate, pitolisant, solriamfetol, and pemoline.
  • Use of sleep‑promoting or sedating medicines (prescription or over‑the‑counter) within five half‑lives before screening and until after the final visit. Examples include OTC sleep aids, trazodone, hypnotics, benzodiazepines, barbiturates, cannabinoids, melatonin, melatonin‑receptor agonists, dual orexin receptor antagonists, and opioids.
  • Inability to stop strong (e.g., itraconazole, clarithromycin) or moderate (e.g., fluconazole) CYP3A inhibitors within five half‑lives before dosing and until after the final visit.
  • Inability to stop CYP3A inducers (e.g., rifampicin, phenytoin) within five half‑lives before dosing and until after the final visit.
  • History of drug or alcohol dependence or abuse within 2 years before screening, or a positive drug or alcohol test at screening.
  • Not agreeing to avoid recreational drugs during the study.
  • Currently enrolled in another clinical study or having used any investigational drug or device within 28 days (or five half‑lives, whichever is longer) before giving consent.
  • Having received blood products within 4 weeks, donated blood within 8 weeks, or donated plasma within 1 week before the first dose.
  • Previous participation in a study of an orexin agonist if the drug was stopped because of side effects or lack of effect.
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Investigated drugs

E2086 is an experimental oral tablet being studied as a possible treatment for narcolepsy. In this trial, participants take the tablet by mouth to see if it can help reduce excessive daytime sleepiness, which is a common problem for people with narcolepsy. The study compares how well E2086 works against a placebo, measuring improvements with a test that records how quickly a person can stay awake. The goal is to find out if E2086 can safely and effectively improve alertness during the day.

What is already known about the treatment

E2086 - This medication is taken by mouth as a film‑coated tablet. It is still experimental and is being studied in clinical trials, so it is not yet approved for general medical use. The drug is being tested to help adults with narcolepsy reduce daytime sleepiness. It works by activating the brain’s orexin‑2 receptors, which helps keep the brain awake, and it belongs to the class of wake‑promoting agents (orexin receptor agonists).

Investigated diseases

Narcolepsy - Narcolepsy is a chronic neurological disorder that causes overwhelming daytime sleepiness and sudden sleep attacks. It often begins in adolescence or early adulthood and may be accompanied by brief episodes of muscle weakness called cataplexy. The condition usually progresses with more frequent daytime sleep episodes and can disrupt nighttime sleep. Over time, the main symptoms tend to remain stable, though their intensity may vary from day to day. People experience ongoing sleepiness and any associated features throughout life.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-523503-30-00Protocol codeE2086-G000-202Estimated enrolment64 patientsSponsorEisai Limited

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