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

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.

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).

Inclusion Criteria:

• 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

Exclusion Criteria:

• 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
• 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