A Phase 2 interventional study of E2086 and Placebo in Narcolepsy, sponsored by Eisai Inc.. Recruiting at 57 sites in 10 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-14.
Sponsored by Eisai Inc. · Phase 2, Interventional, and Treatment
The primary purpose of this study is to evaluate the optimal doses of E2086 compared to placebo in participants with narcolepsy for reduction of excessive daytime sleepiness (EDS) as assessed by Mean Sleep Latency (MSL) (measured from the first 4 maintenance of wakefulness tests [MWTs]).
157 studies on the registry are indexed under Narcolepsy; 37 are open to participants now.
This study's planned enrollment of 64 is below the median of 78 across 114 interventional studies indexed under Narcolepsy.
Browse Narcolepsy studies →Eisai Inc. is the lead sponsor of 368 studies on the registry; 7 are open to participants now.
Of its 83 completed or terminated interventional studies of FDA-regulated products, 56 (67%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Participants must meet all of the following criteria to be included in this study:
NT1 Cohort: Must fulfill Inclusion Criteria 2a and 2b
Diagnosis of NT1 within the last 10 years of screening, as confirmed by at least one of the following:
Exclusion Criteria:
Females of who:
Within 28 days before study entry, did not use a highly effective method of , which includes any of the following:
Participants on an oral contraceptive must use an additional study method throughout the study and for 28 days after study drug discontinuation. For sites outside of Europe, it is permissible that if a highly effective method of contraception is not appropriate or acceptable to the participant, then the participant must agree to use a medically acceptable method of contraception, that is, double-barrier methods of contraception such as latex or synthetic condom plus diaphragm or cervical/vault cap with spermicide.
NOTE: All females will be considered to be of childbearing potential unless they are (amenorrheic for at least 12 consecutive months, in the appropriate age group, and without other known or suspected cause) or have been sterilized surgically (that is, bilateral tubal ligation, total hysterectomy, or bilateral oophorectomy, all with surgery at least 1 month before dosing).
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants with NT1 will be randomly assigned to receive one E2086 matched placebo tablet, orally, once daily for 4 weeks during each of the E2086 low-, middle-, and high-dose-matched treatment periods. A washout period of at least 7 days will be included between dose levels, for a total of approximately 14 weeks of treatment.
Drug: Placebo
Participants with NT1 will be randomly assigned to receive one E2086 tablet, orally, once daily for 4 weeks during each of the E2086 low-, middle-, and high-dose-matched treatment periods. A washout period of at least 7 days will be included between dose levels, for a total of approximately 14 weeks of treatment.
Drug: E2086
Participants with NT2 will be randomly assigned to receive one E2086 matched placebo tablet, orally, once daily for 4 weeks during each of the E2086 low-, middle-, and high-dose-matched treatment periods. A washout period of at least 7 days will be included between dose levels, for a total of approximately 14 weeks of treatment.
Drug: Placebo
Participants with NT2 will be randomly assigned to receive one E2086 tablet, orally, once daily for 4 weeks during each of the E2086 low-, middle-, and high-dose-matched treatment periods. A washout period of at least 7 days will be included between dose levels, for a total of approximately 14 weeks of treatment.
Drug: E2086
E2086 oral tablets.
E2086 matching placebo tablet.
Change from Baseline to Week 4 in MSL for E2086 Compared With Placebo Across Four MWTs in Participants With NT1 and NT2
Sleep latency is defined as the amount of time a person takes to fall asleep. The MWT is an objective measure of the ability to stay awake. An increased ability to stay awake in the context of trying to remain awake is reflected in a prolonged sleep latency. The first 4 measurements of sleep latency at regular intervals across the day are averaged to calculate the MSL. The MWT is used to evaluate response to treatment for conditions associated with EDS and to assess alertness in individuals who must remain awake for safety reasons. The 40-minute MWT will be performed as per the 2021 guidance of the American Academy of Sleep Medicine (AASM).
Time frame: Baseline and Week 4
Weekly Cataplexy Rate (WCR) of E2086 Compared With Placebo at Week 4 in Participants With NT1
WCR assess through participant-reported daily diaries, is a standard measure of cataplexy burden in clinical development programs for narcolepsy treatments, similar in importance to the MWT used for evaluating EDS.
Time frame: At Week 4
Change From Baseline in the Epworth Sleepiness Scale (ESS) Total Score to Week 4 for E2086 Compared With Placebo in Participants With NT1 and NT2
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. Scores above 10 are considered indicative of EDS. A decrease from baseline in ESS score represents improvement.
Time frame: Baseline and Week 4
Number of Participants With Treatment-emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs) in Participants With NT1 and NT2
Time frame: From first dose of study drug up to Day 113
Number of Participants With Markedly Abnormal Laboratory Values in Participants With NT1 and NT2
Laboratory parameters will include hematology, chemistry and urinalysis.
Time frame: Up to Day 113
Number of Participants With Clinically Significant Changes in Vital Sign Values in Participants With NT1 and NT2
Vital signs will include measurement of systolic and diastolic blood pressure (BP), heart rate, respiratory rate and body temperature. Any clinically significant change in vital signs will be determined at the investigator's discretion.
Time frame: Up to Day 113
Number of Participants With Clinically Significant Changes in 12-Lead Electrocardiogram (ECG) Parameters in Participants With NT1 and NT2
The 12-lead ECG will be evaluated. Any clinically significant change in ECG assessment will be determined at the investigator's discretion.
Time frame: Up to Day 113
Number of Participants With Suicidality as Assessed by Columbia - Suicide Severity Rating Scale (C-SSRS) in Participants With NT1 and NT2
Suicidality will be assessed using the C-SSRS. The C-SSRS assesses an individual's degree of suicidality, including suicidal ideation and suicidal behavior. The C-SSRS is an interview-based rating scale to systematically assess any suicidality, suicidal behaviour, or suicidal ideation. Any suicidality is emergence of any suicidal ideation or suicidal behaviour. Any suicidal behaviour is indicated when response is "yes" for any these questions- actual attempt to suicide, engaged in non-suicidal self-injurious behaviour, interrupted attempt, aborted attempt, preparatory acts. Any suicidal ideation is indicated when response is "yes" for any of these questions- wish to be dead, non-specific active suicidal thoughts, active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent to suicide.
Time frame: Up to Day 113
Mean Change From Baseline in 24-hours Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) up to Week 4 of each dose level in Participants With NT1 and NT2
The BP will be evaluated by Ambulatory Blood Pressure Monitoring (ABPM) for all participants based on the measurement of BP recordings after every 24 hours.
Time frame: Baseline and Week 4
Mean Change From Baseline in Day-time and Night-time BP Measured by ABPM in Participants With NT1 and NT2
The BP will be evaluated by ABPM for all participants based on the measurement of BP recordings after every 24 hours.
Time frame: Baseline and Week 4
Cmax: Maximum Observed Plasma Concentration of E2086 and its Metabolite M1
Time frame: Days 28, 63 and 98: 0-24 hours post-dose
Tmax: Time to Reach Cmax of E2086 and its Metabolite M1
Time frame: Days 28, 63 and 98: 0-24 hours post-dose
AUC(0-24h): Area Under the Plasma Concentration-time Curve From Zero Time to 24 Hours of E2086 and its Metabolite M1
Time frame: Days 28, 63 and 98: 0-24 hours post-dose
t½: Terminal Phase Half-life of E2086 and its Metabolite M1
Time frame: Days 28, 63 and 98: 0-24 hours post-dose
MRp: Metabolite Ratio of AUC(0-t)
MRp calculated as ratio of plasma AUC(0-t) of metabolite to parent following molar correction where appropriate. AUC(0-t) is area under the plasma concentration-time curve from zero time to time of last quantifiable concentration of E2086 and its Metabolite M1.
Time frame: Days 28, 63 and 98: 0-24 hours post-dose
Plan to share: Yes — Eisai's data sharing commitment and further information on how to request data can be found on our website http://eisaiclinicaltrials.com/.
No publications or documents are linked to this record.
Started Mar 2026 (actual). Primary completion is estimated for Feb 2027, 10 months after the start.
Of 15 phase 2 interventional studies under Narcolepsy, half reached primary completion within 14 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 44. This study's planned 10 months is below that.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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Studies of the drug tested here: Ledasorexton