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

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

MK-4646 Multiple Dose Trial in Participants With Human Immunodeficiency Virus Type 1 (HIV-1) (MK-4646-003) (NCT07042945) is a Phase 1 interventional studying HIV Infection, sponsored by Merck Sharp & Dohme LLC. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

What Stage of Research Is This?

Phase 1 trials test a new treatment for the first time in humans, focusing on safety, dosing, and how the body processes the drug. For HIV Infection, a Phase 1 study typically enrolls a small number of participants — often healthy volunteers or patients who have exhausted standard treatment options. Phase 1 results determine whether a treatment moves into larger Phase 2 efficacy studies.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

With a target enrollment of 28 participants, this is a small study — typical of early-phase research, rare-disease trials, or pilot studies designed to generate preliminary signal before a larger study is launched.

Who May Be Eligible (Plain English)

Who May Qualify: - 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 Should NOT Join This Trial: - 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 Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

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: * 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

Treatments Being Tested

DRUG

MK-4646

MK-4646 in capsular form administered orally

Locations (2)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

PMSI Republican Clinical Hospital "T.Mosneaga" ( Site 0002)

Chisinau, Moldova

ARENSIA Exploratory Medicine ( Site 0001)

Bucharest, București, Romania

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT07042945), the sponsor (Merck Sharp & Dohme LLC), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT07042945 clinical trial studying?

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. The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Who can participate in NCT07042945?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT07042945?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT07042945. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT07042945. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.