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NCT Number: NCT07266831

A Clinical Study of Islatravir and Ulonivirine for People With HIV-1 Who Have Not Been Treated Before (MK-8591B-062)

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.

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Key information

Conditions

Human Immunodeficiency Virus Type 1 (HIV-1) Infection Acquired Immunodeficiency Syndrome Blood-Borne Infections Communicable Diseases Genital Diseases HIV Infections Immune System Diseases Immunologic Deficiency Syndromes Infections Lentivirus Infections RNA Virus Infections Retroviridae Infections Sexually Transmitted Diseases Sexually Transmitted Diseases, Viral Slow Virus Diseases Urogenital Diseases Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2 / Phase 3

Primary location

Fundación Huesped ( Site 3100), CABA, Buenos Aires, Argentina

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Phase 2: Is human immunodeficiency virus type 1 (HIV-1) positive with Plasma HIV-1 ribonucleic acid (RNA) ≥500 and ≤100,000 copies/mL.
  • Phase 3: Is HIV-1 positive with Plasma HIV-1 RNA ≥500 copies/mL.
  • Phase 2: Has cluster of differentiation 4-positive (CD4+) T-cell count ≥200 cells/mm^3.
  • Is naïve to antiretroviral therapy (ART), defined as having received no prior therapy with any antiretroviral agent following a diagnosis of HIV 1 infection.

Exclusion criteria

  • Has human immunodeficiency virus type 2 (HIV-2) infection.
  • Has a diagnosis of an active acquired immune deficiency syndrome (AIDS)-defining opportunistic infection.
  • Has active hepatitis C virus (HCV) or active hepatitis B virus (HBV) infection.
  • Has a history of malignancy ≤5 years prior to providing documented informed consent except for adequately treated basal cell or squamous cell skin cancer, in situ cervical or in situ anal cancer, or cutaneous Kaposi's sarcoma.
  • Has prior exposure to islatravir (ISL) or ulonivirine (ULO) for any duration any time prior to Day 1.

Treatment and study plan

ISL

Drug

ISL 2 x 1 mg oral capsules administered qw for 96 weeks

Other names: islatravir, MK-8591

ULO

Drug

ULO 2 x 100 mg oral tablets administered qw for 96 weeks

Other names: ulonivirine, MK-8507

BIC/FTC/TAF

Drug

BIC/FTC/TAF 50/200/25 mg oral tablet administered qd for 96 weeks

Other names: bictegravir/emtricitabine/tenofovir alafenamide, BIKTARVY®

Placebo for BIC/FTC/TAF

Drug

BIC/FTC/TAF-matching placebo oral tablet administered qd for 96 weeks

Placebo to ISL/ULO

Drug

ISL/ULO-matching placebo oral tablets administered qw for 96 weeks

ISL/ULO

Drug

ISL/ULO fixed-dose combination 2 mg/200 mg oral tablet administered qw for 96 weeks

Other names: MK-8591B

Primary outcomes

  1. Phase 2: Percentage of Participants With Human Immunodeficiency Virus Type 1 (HIV-1) Ribonucleic Acid (RNA) <50 Copies/mL at Week 24

    Time frame: 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.

  2. Phase 2: Percentage of Participants Who Experience an Adverse Event (AE) at Week 24

    Time frame: 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.

  3. Phase 2: Percentage of Participants Who Discontinue Study Intervention Due to an AE at Week 24

    Time frame: 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.

  4. Phase 3: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 48

    Time frame: 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.

  5. Phase 3: Percentage of Participants Who Experience an AE at Week 48

    Time frame: 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.

  6. Phase 3: Percentage of Participants Who Discontinue Study Intervention Due to an AE at Week 48

    Time frame: 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.

Secondary outcomes

  1. Phase 2: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 48

    Time frame: 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.

  2. Phase 2: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 96

    Time frame: 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.

  3. Phase 2: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 24

    Time frame: 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.

  4. Phase 2: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 48

    Time frame: 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.

  5. Phase 2: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 96

    Time frame: 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.

  6. Phase 2: Mean Change From Baseline in Cluster of Differentiation 4-Positive (CD4+) T-Cell Count at Week 24

    Time frame: Baseline (Day 1) and 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.

  7. Phase 2: Mean Change From Baseline in CD4+ T-Cell Count at Week 48

    Time frame: Baseline (Day 1) and 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.

  8. Phase 2: Mean Change From Baseline in CD4+ T-Cell Count at Week 96

    Time frame: Baseline (Day 1) and 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.

  9. Phase 2: Percentage of Participants Who Experience an AE

    Time frame: Up to approximately 102 weeks

    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.

  10. Phase 2: Percentage of Participants Who Discontinue Study Intervention Due to an AE

    Time frame: Up to approximately 96 weeks

    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.

  11. Phase 2: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 24

    Time frame: 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.

  12. Phase 2: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 48

    Time frame: 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.

  13. Phase 2: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 96

    Time frame: 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.

  14. Phase 3: Percentage of Participants With HIV-1 RNA <50 Copies/mL at Week 96

    Time frame: 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.

  15. Phase 3: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 48

    Time frame: 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.

  16. Phase 3: Percentage of Participants With HIV-1 RNA <200 Copies/mL at Week 96

    Time frame: 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.

  17. Phase 3: Mean Change From Baseline in Cluster of Differentiation 4-Positive (CD4+) T-Cell Count at Week 48

    Time frame: Baseline (Day 1) and 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.

  18. Phase 3: Mean Change From Baseline in Cluster of Differentiation 4-Positive (CD4+) T-Cell Count at Week 96

    Time frame: Baseline (Day 1) and 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.

  19. Phase 3: Percentage of Participants Who Experience an AE

    Time frame: Up to approximately 102 weeks

    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.

  20. Phase 3: Percentage of Participants Who Discontinue Study Intervention Due to an AE

    Time frame: Up to approximately 96 weeks

    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.

  21. Phase 3: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 48

    Time frame: 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.

  22. Phase 3: Number of Participants With Evidence of Viral Drug Resistance-Associated Substitutions at Week 96

    Time frame: 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.

  23. Phase 3: Mean Change From Baseline in Body Weight at Week 48

    Time frame: Baseline (Day 1) and Week 48

    Body weight will be collected throughout the study.

  24. Phase 3: Mean Change From Baseline in Body Weight at Week 96

    Time frame: Baseline (Day 1) and Week 96

    Body weight will be collected throughout the study.

Study contacts

Contact information is provided by the study sponsor or research team.

Toll Free Number

CONTACT

[email protected]

1-888-577-8839

Sponsors and collaborators

Lead sponsor

Merck Sharp & Dohme LLC

Industry

Registry information

Official study title

A Phase 2/3, Randomized, Active-Controlled, Open-Label (Phase 2) and Double-Blind (Phase 3) Study to Evaluate the Antiretroviral Activity, Safety, and Tolerability of Islatravir (ISL) and Ulonivirine (ULO) Once Weekly Compared With Bictegravir/Emtricitabine/Tenofovir Alafenamide (BIC/FTC/TAF) Once Daily in Treatment-Naïve Adult Participants Living With HIV-1

Important dates

Study start
2025
Primary completion
2029
Study completion
2030
First posted
Dec 5, 2025
Registry last updated
Jul 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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