CompletedNCT07042945Updated Jun 22, 2026

MK-4646 Multiple Dose Trial in Participants With Human Immunodeficiency Virus Type 1 (HIV-1) (MK-4646-003)

A Phase 1 interventional study of MK-4646 in HIV Infection, sponsored by Merck Sharp & Dohme LLC. Completed at 2 sites in 2 countries. Open to participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-06-22.

Sponsored by Merck Sharp & Dohme LLC · Phase 1, Interventional, and Treatment

Phase: Phase 1
Study type: Interventional
Enrollment: 15
Allocation: Randomized
Ages: 18 Years to 60 Years
Sex: All

Study summary

This study will examine if at least one dose level of MK-4646 can lower HIV-1 viral load in a person's blood by a certain amount. The goals of this study are to learn about the safety of MK-4646 and if people tolerate it; and how HIV-1 viral load may decrease after starting to take MK-4646.

Conditions studied

HIV Infection

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In context

HIV Infections

4,257 studies on the registry are indexed under HIV Infections; 240 are open to participants now.

This study's enrollment of 15 is below the median of 83 across 3,250 interventional studies indexed under HIV Infections.

Browse HIV Infections studies →

Lead sponsor

Merck Sharp & Dohme LLC is the lead sponsor of 2,114 studies on the registry; 133 are open to participants now.

Of its 489 completed or terminated interventional studies of FDA-regulated products, 362 (74%) have results posted.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 18 Years to 60 Years
Sexes eligible: All
Accepts healthy volunteers: No

Inclusion criteria

Other than having HIV-1, is in good health
Is antiretroviral therapy (ART)-naïve
If ART-experienced has not received any antiretroviral therapy within 60 days (or 5 half-lives, whichever is longer) prior to screening
Is willing to receive no other ART prior to Day 8 post-dose of the trial
If capable of producing sperm agrees to use contraception
If assigned female sex at birth is not breastfeeding
A participant of childbearing potential (POCBP) is not pregnant and has a negative highly sensitive pregnancy test (urine or serum), and uses a contraceptive method that is highly effective

Exclusion criteria

Exclusion Criteria:

Has acute (primary) HIV-1 infection
Has history of clinically significant endocrine, gastrointestinal (GI), cardiovascular, hematological, hepatic, immunological, renal, respiratory, genitourinary, or major neurological (including stroke and chronic seizures) abnormalities or diseases
Is 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.
Has history of cancer (malignancy)
Has history of significant multiple and/or severe allergies
Tests positive for hepatitis B surface antigen (HBsAg), hepatitis C antibodies
Has had a major surgery and/or donated or lost 1 unit of blood (approximately 500 mL) within 4 weeks prior to the prestudy (screening) visit
Has received any vaccine starting from 30 days prior to study intervention or is scheduled to receive any vaccine through 14 days following study intervention
Is unable to refrain from using protocol specified prohibited medications
Is an excessive smoker, or consumes excessive amounts of alcoholic or caffeinated beverages
Is a regular user of any illicit drugs or has a history of drug (including alcohol) abuse

Study design

Phase: Phase 1
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Sequential assignment
Masking: None (open label)
Enrollment: 15 participants (actual)

Study arms

Experimental
MK-4646 Panel A
MK-4646 160 mg every 24 hours (q24h) for 7 days
Drug: MK-4646
Experimental
MK-4646 Panel B
MK-4646 ≤460 mg q24h for 7 days
Drug: MK-4646
Experimental
MK-4646 Panel C
MK-4646 ≤460 mg q24h for 7 days
Drug: MK-4646
Experimental
MK-4646 Panel D
MK-4646 ≤460 mg every 12 hours (q12h) for 7 days
Drug: MK-4646

Interventions

DrugMK-4646
MK-4646 in capsular form administered orally

What researchers measure

Primary outcomes

Participants with averse events (AEs)
Percentage of participants with one or more AEs
Time frame: 14 days post last dose (Up to Day 23)
Participants who discontinued study medication due to an AE
Percentage of participants who discontinued study medication due to an AE
Time frame: Up to Day 7
Viral load decline of plasma HIV-1 ribonucleic acid (RNA)
Time course of plasma HIV-1 RNA viral load decline.
Time frame: Predose, 1,2, 3, 4 and 5 days postdose

Secondary outcomes

Area under the curve from time 0 to 24 hours (AUC0-24) of MK-4646
AUC0-24 postdose of plasma MK- 4646 in the fasted state
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Maximum plasma concentration (Cmax) of MK-4646
Cmax postdose of plasma MK- 4646 in the fasted state
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Concentration at 24 hours (C24) of MK-4646
C24 postdose of plasma MK- 4646 in the fasted state
Time frame: 24 hours postdose
Time to maximum concentration (Tmax) of MK-4646
Tmax postdose of plasma MK- 4646 in the fasted state
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Half life (t1/2) of MK-4646
T1/2 postdose of plasma MK- 4646 in the fasted state
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose

Study locations

2 sites

PMSI Republican Clinical Hospital "T.Mosneaga" ( Site 0002)
Chisinau, 2025, Moldova
ARENSIA Exploratory Medicine ( Site 0001)
Bucharest, Bucharest 021105, Romania

References and documents

Individual participant data

Plan to share: Yes — https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on Jun 22, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT07042945
Lead sponsor: Merck Sharp & Dohme LLC
Responsible party: Sponsor
First posted: Jun 29, 2025
Start date: Jul 9, 2025
Primary completion: Jun 5, 2026
Completion: Jun 5, 2026
Last update: Jun 22, 2026

Study contacts

Medical Director

study director · Merck Sharp & Dohme LLC

Oversight

Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.

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