HIV InfectionPhase 1NCT07042945
MK-4646 Multiple Dose Trial in Participants With Human Immunodeficiency Virus Type 1 (HIV-1) (MK-4646-003)
A Phase 1 study testing MK-4646 in people with HIV Infection, run by Merck Sharp & Dohme LLC at 2 sites in 2 countries.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 60 years
- Conditions the study is for
- HIV Infection
- What is being tested?
- MK-4646
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 2 sitesin 2 countries
- Study dates
- 9 Jul 2025to 5 Jun 2026
- Phase
- Phase 1
- Are there results?
- None posted in the registry
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 60 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- 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
Who cannot join
- 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
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- 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
Trial locations and contacts
2 sites in 2 countries.
2 sites in 2 countries
Moldova1 site
PMSI Republican Clinical Hospital "T.Mosneaga" ( Site 0002)
Chisinau, 2025
Romania1 site
ARENSIA Exploratory Medicine ( Site 0001)
Bucharest, Bucharest, 021105
About this study
Official title: Multiple Dose Clinical Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Antiretroviral Activity of MK-4646 Monotherapy in Antiretroviral Therapy-Naïve Participants With HIV-1
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
- HIV Infection
- Being tested
- MK-4646
- Medical subject headings
- HIV Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
MK-4646Drug
MK-4646 in capsular form administered orally
| Study group | Role | What they receive |
|---|---|---|
| MK-4646 Panel A | Experimental | MK-4646 160 mg every 24 hours (q24h) for 7 days Receives: Drug: MK-4646 |
| MK-4646 Panel B | Experimental | MK-4646 ≤460 mg q24h for 7 days Receives: Drug: MK-4646 |
| MK-4646 Panel C | Experimental | MK-4646 ≤460 mg q24h for 7 days Receives: Drug: MK-4646 |
| MK-4646 Panel D | Experimental | MK-4646 ≤460 mg every 12 hours (q12h) for 7 days Receives: Drug: MK-4646 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Participants with averse events (AEs)
Percentage of participants with one or more AEs
Measured: 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
Measured: Up to Day 7
Viral load decline of plasma HIV-1 ribonucleic acid (RNA)
Time course of plasma HIV-1 RNA viral load decline.
Measured: Predose, 1,2, 3, 4 and 5 days postdose
Secondary outcomes (5)
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
Measured: 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
Measured: 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
Measured: 24 hours postdose
Time to maximum concentration (Tmax) of MK-4646
Tmax postdose of plasma MK- 4646 in the fasted state
Measured: 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
Measured: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Jun 2025
- Study start9 Jul 2025
- Primary completion5 Jun 2026
- Study completion5 Jun 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HIV InfectionStudies of the same condition, open and under way.
- More trials run by Merck Sharp & Dohme LLCThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- None (open label)
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- Merck Sharp & Dohme LLC
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Medical Director, Study director, Merck Sharp & Dohme LLC
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07042945
- Sponsor's protocol ID
- 4646-003
- Other IDs
- MK-4646-003, 2025-521102-17-00, U1111-1318-7985, 2025
- Status last verified
- Jun 2026
- First submitted
- 9 Jun 2025
- Last updated
- 22 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
Study at a glance
From the registry record, last updated by the sponsor on 22 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Multiple Dose Clinical Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Antiretroviral Activity of MK-4646 Monotherapy in Antiretroviral Therapy-Naïve Participants With HIV-1
- ClinicalTrials.gov ID
- NCT07042945
- Acronym / sponsor ID
- 4646-003
- Conditions
- HIV Infection
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 15 participants (actual)
- Lead sponsor
- Merck Sharp & Dohme LLCIndustry (pharma, biotech, devices)
- Study start
- 9 Jul 2025 (actual)
- Primary completion
- 5 Jun 2026 (actual)
- Study completion
- 5 Jun 2026 (actual)
- First posted
- 29 Jun 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| MK-4646 Panel A | Experimental | Drug: MK-4646MK-4646 160 mg every 24 hours (q24h) for 7 days |
| MK-4646 Panel B | Experimental | Drug: MK-4646MK-4646 ≤460 mg q24h for 7 days |
| MK-4646 Panel C | Experimental | Drug: MK-4646MK-4646 ≤460 mg q24h for 7 days |
| MK-4646 Panel D | Experimental | Drug: MK-4646MK-4646 ≤460 mg every 12 hours (q12h) for 7 days |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- 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
Key exclusion criteria (11 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| MK-4646MK-4646 in capsular form administered orally | Drug | MK-4646 Panel A, MK-4646 Panel B, MK-4646 Panel C, MK-4646 Panel D |
Primary outcome
Participants with averse events (AEs)
Time frame: 14 days post last dose (Up to Day 23)
Percentage of participants with one or more AEs
Participants who discontinued study medication due to an AE
Time frame: Up to Day 7
Percentage of participants who discontinued study medication due to an AE
Viral load decline of plasma HIV-1 ribonucleic acid (RNA)
Time frame: Predose, 1,2, 3, 4 and 5 days postdose
Time course of plasma HIV-1 RNA viral load decline.
5 secondary outcomes
Area under the curve from time 0 to 24 hours (AUC0-24) of MK-4646
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Maximum plasma concentration (Cmax) of MK-4646
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Concentration at 24 hours (C24) of MK-4646
Time frame: 24 hours postdose
Time to maximum concentration (Tmax) of MK-4646
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Half life (t1/2) of MK-4646
Time frame: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24 hours postdose
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Jun 2026.
- Merck Clinical Trials InformationLink provided by the sponsor.
- Plain Language SummaryLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Medical Director study director
Merck Sharp & Dohme LLC
2 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing MK-4646 in people with HIV Infection, run by Merck Sharp & Dohme LLC at 2 sites in 2 countries.
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 7 inclusion and 11 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: finished, as of the sponsor's last update on 22 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Moldova, Romania. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Participants with averse events (AEs) (time frame: 14 days post last dose (Up to Day 23)). 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 22 Jun 2026.