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NarcolepsyPhase 1NCT06179407

Study of MK-6552 in Participants With Narcolepsy Type 1 (MK-6552-004)

A Phase 1 study testing MK-6552 in people with Narcolepsy, run by Merck Sharp & Dohme LLC at 5 sites in United States.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record
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Trial summary

The purpose of this study was to evaluate the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of MK-6552 in participants with Narcolepsy Type 1 (NT1). The effect of single MK-6552 doses were assessed initially under open-label conditions to evaluate the safety, tolerability, and PK of MK-6552. Read more about this study

Who is it for?
Ages 18 to 55 years
Conditions the study is for
Narcolepsy
What is being tested?
MK-6552
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
9 participants
Where
5 sitesUnited States
Study dates
24 Jan 2024to 23 Oct 2024
Phase
Phase 1
Are there results?
Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 55 years
  • All sexes
  • No healthy volunteers
  • Adult

Who may be able to join

  • Has a diagnosis of NT1, including a valid polysomnography within the previous 5 years and a current diagnosis of NT1 for at least 6 months based on criteria established by the International Classification of Sleep Disorders- Third Edition, or Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) [American Psychiatric Association 2013]
  • Is positive for HLA-DQB1*06:02 allele supporting a diagnosis of NT1
  • Has a baseline history of unequivocal cataplexy prior to initiation of anti-cataplexy medications
  • Reports a total sleep time of > 6 hours on at least 4 out of 7 nights each week within the 4 weeks prior to screening visit

Who cannot join

  • Has history of or current hypertension
  • Has underlying cardiovascular or cerebrovascular conditions in which an acute rise in blood pressure would pose a clinical concern, including but nor limited to aneurysms or arteriovenous malformations
  • Has a history of renal or hepatic impairment
  • Has a history of cardiac ischemia or cerebral ischemia including but not limited to history of stroke, transient ischemic attack, or transient global amnesia
  • Based on clinical interview and responses on the Columbia-Suicide Severity Rating Scale, is at imminent risk of self-harm or of harm to others in the opinion of the investigator
  • Mentally or legally incapacitated, has significant emotional problems at the time of prestudy (screening) visit or expected during the conduct of the study or has a history of clinically significant psychiatric disorder of the last 5 years
Show all 10Show fewer
  • History of cancer (malignancy)
  • Has a history of any of the following sleep disorders: obstructive sleep apnea (OSA) defined as an Apnea Hypopnea Index > 15 per hour per the American Academy of Sleep Medicine alternate criteria, primary insomnia (within the past 6 months), circadian rhythm sleep disorder, shift work sleep disorder (within the past 6 months), clinically significant parasomnia at the discretion of the investigator
  • Has a history of seizure disorder, clinically significant head trauma, or past invasive intracranial surgery or clinically significant dementia
  • Positive test(s) for Hepatitis B surface antigen, hepatitis C antibodies, or human immunodeficiency virus

Trial locations and contacts

5 sites in 1 country.

5 sites in 1 country

United States5 sites
  • NeuroTrials Research Inc ( Site 0006)

    Atlanta, Georgia, 30328

  • FutureSearch Trials of Neurology ( Site 0004)

    Austin, Texas, 78731

  • Teradan Clinical Trials, LLC ( Site 0005)

    Brandon, Florida, 33511

  • Delta Waves, Inc. ( Site 0008)

    Colorado Springs, Colorado, 80918

  • Bogan Sleep Consultants ( Site 0001)

    Columbia, South Carolina, 29201

Other trials in United States

About this study

Official title: A Two-Part Study to Assess the Safety, Tolerability, Pharmacokinetics and Sleep Latency Effects of MK-6552 in Participants With Narcolepsy Type 1

The purpose of this study was to evaluate the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of MK-6552 in participants with Narcolepsy Type 1 (NT1). The effect of single MK-6552 doses were assessed initially under open-label conditions to evaluate the safety, tolerability, and PK of MK-6552. The effect of repeated MK-6552 doses (every 8 hours [q8h] for 7 days) were assessed under double-blind and placebo-controlled conditions.

Read the detailed description

The study was terminated by the Sponsor on 15OCT2024 out of an abundance of caution regarding elevations in liver function tests in 3 participants (all cases were asymptomatic and none met Hy's law for drug-induced liver injury or SAE criteria).

Conditions
Narcolepsy
Being tested
MK-6552, Placebo
Medical subject headings
Narcolepsy

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • MK-6552Drug

    Oral capsule

  • PlaceboDrug

    Oral capsule matched to MK-6552

Study groups in NCT06179407
Study groupRoleWhat they receive
Panel AExperimentalParticipants will receive single oral doses of MK-6552 in ascending fashion approximately 6 hours apart for a single day, based on safety and tolerability of the previous dose. Then, participants will receive multiple days of MK-6552 dosing (7 consecutive days) at the highest safe and well tolerated MK-6552 dose determined on an individual basis from Part 1.
Receives: Drug: MK-6552; Drug: Placebo
Panel BExperimentalPanel B will assess the effects of repeated MK-6552 dosing across a range of doses compared with placebo.
Receives: Drug: MK-6552; Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of Participants Experiencing an Adverse Event (AE)

    An AE is any untoward medical occurrence in a participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Events are reported according to dose. The number of participants with ≥1 AE is reported.

    Measured: Up to ~34 weeks

  2. Number of Participants Discontinuing Study Intervention Due to AE

    An AE is any untoward medical occurrence in a participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Events are reported according to dose. The number of participants that discontinued study intervention due to AE(s) is reported.

    Measured: Up to ~34 weeks

  3. Sleep Onset Latency Measured by the Maintenance of Wakefulness Test (MWT) Following 7 Days of MK-6554 Treatment

    The MWT is a daytime polysomnographic procedure that measures objectively the ability to remain awake during sleep-inducing circumstances. Sleep onset latency is defined as the first occurrence of sustained sleep (i.e. 3 consecutive 30 second epochs of N1 [stage 1] sleep or any single 30 second epoch of N2 [stage 2], N3 [stage 3 and 4 combined] or REM). The primary outcome measure of sleep onset latency measured by the MWT on Day 7 of daily repeated MK-6552 treatment is reported.

    Measured: 1 hour after Dose 1 and Dose 2 on Day 7

Secondary outcomes (10)
  1. Area Under the Plasma Concentration-Time Curve of MK-6552 From Time Zero to Infinity (AUC0-∞)

    The AUC0-∞ of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose

  2. Area Under the Plasma Concentration-Time Curve of MK-6552 From Time Zero to 24 Hours Postdose (AUC0-24)

    The AUC0-24 of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, and 18 hours postdose

  3. Maximum Concentration (Cmax) of MK-6552

    The Cmax of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose

  4. Time to Maximum Concentration (Tmax) of MK-6552

    The Tmax of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose

  5. Concentration of MK-6522 at 2 Hours Postdose (C2h)

    The C2h of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: 2 hours postdose. Day 1 Dose 2: 2 hours postdose.

  6. Concentration of MK-6522 at 6 Hours Postdose (C6h)

    The C6h of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: 6 hours postdose

  7. Concentration of MK-6522 at 18 Hours Postdose (C18h)

    The C18h of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 2: 18 hours postdose

  8. Apparent Oral Clearance (CL/F) of MK-6552

    The CL/F of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose

  9. Apparent Volume of Distribution (Vz/F) of MK-6552

    The Vz/F of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose

  10. Apparent Terminal Half-life (t½) of MK-6552

    The apparent t½ of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.

    Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted21 Dec 2023
  2. Study start24 Jan 2024
  3. Primary completion23 Oct 2024
  4. Study completion23 Oct 2024

Why it stopped: Terminated for business reasons

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Sequential
Masking
Single blind
Who is masked
Participant
Enrolment
9 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06179407
Sponsor's protocol ID
6552-004
Other IDs
MK-6554-004
Status last verified
Mar 2026
First submitted
12 Dec 2023
Last updated
14 Apr 2026
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing MK-6552 in people with Narcolepsy, run by Merck Sharp & Dohme LLC at 5 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: stopped early, as of the sponsor's last update on 14 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 5 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 14 Apr 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants Experiencing an Adverse Event (AE) (time frame: Up to ~34 weeks). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Apr 2026.

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