A Phase 2/3 interventional study of ISL and ULO in Human Immunodeficiency Virus Type 1 (HIV-1) Infection, sponsored by Merck Sharp & Dohme LLC. Recruiting at 56 sites in 9 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by Merck Sharp & Dohme LLC (part of Merck & Co., Inc) · Phase 2/3, Interventional, and Treatment
Researchers are looking for new ways to treat HIV-1 (Human Immunodeficiency Virus Type 1). The usual (standard) treatment for HIV-1 is antiretroviral therapy (ART), which includes taking medicines to lower the amount of HIV-1 in the body. Standard ART helps people live longer, but people must take up to 3 medicines up to twice a day. Standard ART may also cause other health problems. Researchers want to know if a study ART works as well as a standard ART to treat HIV-1. The study ART combines 2 medicines, islatravir and ulonivirine, and is taken once a week. The goals of this study are to learn: 1) If the study ART works as well as a standard ART to treat HIV-1, and 2) About the safety of the study ART and if people tolerate it compared to a standard ART.
2,093 studies on the registry are indexed under Infections; 364 are open to participants now.
This study's planned enrollment of 570 is above the median of 113 across 1,304 interventional studies indexed under Infections.
Browse Infections studies →Merck Sharp & Dohme LLC is the lead sponsor of 2,166 studies on the registry; 132 are open to participants now.
Of its 501 completed or terminated interventional studies of FDA-regulated products, 370 (74%) have results posted.
Compared within Infections, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Acquired Immunodeficiency Syndrome. The counts are of registry records indexed under each term, refreshed daily. How we classify →
The criteria were revised on the registry on Oct 13, 2026. See what changed
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Islatravir (ISL) 2mg and Ulonivirine (ULO) 200mg administered orally once weekly (qw) for 96 weeks
Drug: ISL · Drug: ULO
Bictegravir/Emtricitabine/Tenofovir Alafenamide (BIC/FTC/TAF) 50/200/25 mg, administered orally once daily (qd) for 96 weeks
Drug: BIC/FTC/TAF
ISL/ULO fixed dose combination (2/200 mg), administered orally qw, and matching placebo to BIC/FTC/TAF administered orally qd for 96 weeks
Drug: Placebo for BIC/FTC/TAF · Drug: ISL/ULO
BIC/FTC/TAF 50/200/25 mg, administered orally qd, and matching placebo to ISL/ULO administered orally qw for 96 weeks
Drug: BIC/FTC/TAF · Drug: Placebo to ISL/ULO
ISL 2 x 1 mg oral capsules administered qw for 96 weeks
Also known as: islatravir, MK-8591
ULO 2 x 100 mg oral tablets administered qw for 96 weeks
Also known as: ulonivirine, MK-8507
Drug pages: Bictegravir · Emtricitabine · Tenofovir alafenamide
BIC/FTC/TAF 50/200/25 mg oral tablet administered qd for 96 weeks
Also known as: bictegravir/emtricitabine/tenofovir alafenamide, BIKTARVY®
BIC/FTC/TAF-matching placebo oral tablet administered qd for 96 weeks
ISL/ULO-matching placebo oral tablets administered qw for 96 weeks
ISL/ULO fixed-dose combination 2 mg/200 mg oral tablet administered qw for 96 weeks
Also known as: MK-8591B
Phase 2: Percentage of Participants With Human Immunodeficiency Virus Type 1 (HIV-1) Ribonucleic Acid (RNA) <50 Copies/mL at Week 24
Plasma HIV-1 ribonucleic acid (RNA) quantification will be performed at the central laboratory using a polymerase chain reaction (PCR) assay. Percentage of participants with HIV-1 RNA \<50 copies/mL will be reported at week 24.
Time frame: Week 24
Phase 2: Percentage of Participants Who Experience an Adverse Event (AE) at Week 24
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Week 24
Phase 2: Percentage of Participants Who Discontinue Study Intervention Due to an AE at Week 24
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Week 24
Phase 3: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 48
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<50 copies/mL will be reported at week 48.
Time frame: Week 48
Phase 3: Percentage of Participants Who Experience an AE at Week 48
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Week 48
Phase 3: Percentage of Participants Who Discontinue Study Intervention Due to an AE at Week 48
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Week 48
Phase 2: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 48
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<50 copies/mL will be reported at week 48.
Time frame: Week 48
Phase 2: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 96
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<50 copies/mL will be reported at week 96.
Time frame: Week 96
Phase 2: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 24
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<200 copies/mL will be reported at week 24.
Time frame: Week 24
Phase 2: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 48
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<200 copies/mL will be reported at week 48.
Time frame: Week 48
Phase 2: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 96
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<200 copies/mL will be reported at week 96.
Time frame: Week 96
Phase 2: Mean Change From Baseline in Cluster of Differentiation 4-Positive (CD4+) T-Cell Count at Week 24
Blood samples will be collected to measure CD4+ T-cell count. The mean change from baseline in CD4+ T-cell count will be calculated at 24 weeks.
Time frame: Baseline (Day 1) and Week 24
Phase 2: Mean Change From Baseline in CD4+ T-Cell Count at Week 48
Blood samples will be collected to measure CD4+ T-cell count. The mean change from baseline in CD4+ T-cell count will be calculated at 48 weeks.
Time frame: Baseline (Day 1) and Week 48
Phase 2: Mean Change From Baseline in CD4+ T-Cell Count at Week 96
Blood samples will be collected to measure CD4+ T-cell count. The mean change from baseline in CD4+ T-cell count will be calculated at 96 weeks.
Time frame: Baseline (Day 1) and Week 96
Phase 2: Percentage of Participants Who Experience an AE
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Up to approximately 102 weeks
Phase 2: Percentage of Participants Who Discontinue Study Intervention Due to an AE
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Up to approximately 96 weeks
Phase 2: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 24
Participants who meet the definition of clinically significant confirmed viremia (CSCV) or who discontinue study intervention for another reason and have HIV-1 RNA ≥200 copies/mL at the time of discontinuation, will be assessed for development of viral drug resistance. Among such participants, those with confirmed HIV-1 RNA ≥400 copies/mL will be included in the resistance analyses set. In addition, anyone for whom available genotypic and/or phenotypic data show evidence of resistance, irrespective of viral load, will also be included in the resistance analyses set. The number of participants in each treatment group who have evidence of resistance-associated substitutions at week 24 will be presented.
Time frame: Week 24
Phase 2: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 48
Participants who meet the definition of clinically significant confirmed viremia (CSCV) or who discontinue study intervention for another reason and have HIV-1 RNA ≥200 copies/mL at the time of discontinuation, will be assessed for development of viral drug resistance. Among such participants, those with confirmed HIV-1 RNA ≥400 copies/mL will be included in the resistance analyses set. In addition, anyone for whom available genotypic and/or phenotypic data show evidence of resistance, irrespective of viral load, will also be included in the resistance analyses set. The number of participants in each treatment group who have evidence of resistance-associated substitutions at week 48 will be presented.
Time frame: Week 48
Phase 2: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 96
Participants who meet the definition of clinically significant confirmed viremia (CSCV) or who discontinue study intervention for another reason and have HIV-1 RNA ≥200 copies/mL at the time of discontinuation, will be assessed for development of viral drug resistance. Among such participants, those with confirmed HIV-1 RNA ≥400 copies/mL will be included in the resistance analyses set. In addition, anyone for whom available genotypic and/or phenotypic data show evidence of resistance, irrespective of viral load, will also be included in the resistance analyses set. The number of participants in each treatment group who have evidence of resistance-associated substitutions at week 96 will be presented.
Time frame: Week 96
Phase 3: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 96
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<50 copies/mL will be reported at week 96.
Time frame: Week 96
Phase 3: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 48
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<200 copies/mL will be reported at week 48.
Time frame: Week 48
Phase 3: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 96
Plasma HIV-1 RNA quantification will be performed at the central laboratory using a PCR assay. Percentage of participants with HIV-1 RNA \<200 copies/mL will be reported at week 96.
Time frame: Week 96
Phase 3: Mean Change From Baseline in Cluster of Differentiation 4-Positive (CD4+) T-Cell Count at Week 48
Blood samples will be collected to measure CD4+ T-cell count. The mean change from baseline in CD4+ T-cell count will be calculated at 48 weeks.
Time frame: Baseline (Day 1) and Week 48
Phase 3: Mean Change From Baseline in Cluster of Differentiation 4-Positive (CD4+) T-Cell Count at Week 96
Blood samples will be collected to measure CD4+ T-cell count. The mean change from baseline in CD4+ T-cell count will be calculated at 96 weeks.
Time frame: Baseline (Day 1) and Week 96
Phase 3: Percentage of Participants Who Experience an AE
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Up to approximately 102 weeks
Phase 3: Percentage of Participants Who Discontinue Study Intervention Due to an AE
An AE is defined as any unfavorable and unintended sign, symptom, disease, or worsening of preexisting condition temporally associated with study treatment and irrespective of causality to study treatment.
Time frame: Up to approximately 96 weeks
Phase 3: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 48
Participants who meet the definition of clinically significant confirmed viremia (CSCV) or who discontinue study intervention for another reason and have HIV-1 RNA ≥200 copies/mL at the time of discontinuation, will be assessed for development of viral drug resistance. Among such participants, those with confirmed HIV-1 RNA ≥400 copies/mL will be included in the resistance analyses set. In addition, anyone for whom available genotypic and/or phenotypic data show evidence of resistance, irrespective of viral load, will also be included in the resistance analyses set. The number of participants in each treatment group who have evidence of resistance-associated substitutions at week 48 will be presented.
Time frame: Week 48
Phase 3: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 96
Participants who meet the definition of clinically significant confirmed viremia (CSCV) or who discontinue study intervention for another reason and have HIV-1 RNA ≥200 copies/mL at the time of discontinuation, will be assessed for development of viral drug resistance. Among such participants, those with confirmed HIV-1 RNA ≥400 copies/mL will be included in the resistance analyses set. In addition, anyone for whom available genotypic and/or phenotypic data show evidence of resistance, irrespective of viral load, will also be included in the resistance analyses set. The number of participants in each treatment group who have evidence of resistance-associated substitutions at week 96 will be presented.
Time frame: Week 96
Phase 3: Mean Change From Baseline in Body Weight at Week 48
Body weight will be collected throughout the study.
Time frame: Baseline (Day 1) and Week 48
Phase 3: Mean Change From Baseline in Body Weight at Week 96
Body weight will be collected throughout the study.
Time frame: Baseline (Day 1) and Week 96
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Plan to share: Yes — https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
Data sharing details ↗ · externaldatasharing-msd.com
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drugs tested here: Islatravir · Ulonivirine