This study will evaluate the safety and efficacy of a switch to MK-8591A (a fixed dose combination of doravirine and islatravir) in human immunodeficiency virus -1 (HIV-1)-infected participants virologically suppressed on a protocol-specified antiretroviral regimen. The primary hypothesis is that a switch to MK-8591A will be non-inferior to continued treatment with baseline antiretroviral therapy (ART) as assessed by the proportion of participants with HIV-1 ribonucleic acid (RNA) ≥50 copies/mL at Week 48.



Eligible Ages
Over 18 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Is HIV-1 positive
  • Has been receiving continuous, stable oral 2-drug or 3-drug combination (± pharmacokinetic (PK) booster) with documented viral suppression (HIV-1 RNA <50 copies/mL) for ≥3 months prior to signing informed consent and has no history of prior virologic treatment failure on any past or current regimen.
  • Female is eligible to participate if she is not pregnant or breastfeeding, and at least one of the following conditions applies: is not a woman of childbearing potential (WOCBP); is a WOCBP and using an acceptable contraceptive method, or be abstinent from heterosexual intercourse as their preferred and usual lifestyle; a WOCBP must have a negative highly sensitive pregnancy test ([urine or serum] as required by local regulations) within 24 hours before the first dose of study intervention; if a urine test cannot be confirmed as negative (e.g. an ambiguous result), a serum pregnancy test is required. In such cases, the participant must be excluded from participation if the serum pregnancy result is positive;

Exclusion Criteria

  • Has HIV-2 infection
  • Has hypersensitivity or other contraindication to any of the components of the study interventions as determined by the investigator
  • Has an active diagnosis of hepatitis due to any cause, including active Hepatitis B Virus (HBV) co-infection
  • Has a history of malignancy ≤5 years prior to signing informed consent except for adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, or cutaneous Kaposi's sarcoma
  • Is taking or is anticipated to require systemic immunosuppressive therapy, immune modulators, or any prohibited therapies
  • Is currently taking long-acting cabotegravir-rilpivirine
  • Is currently participating in or has participated in a clinical study with an investigational compound or device from 45 days prior to Day 1 through the study treatment period
  • Has a documented or known virologic resistance to DOR
  • Female expects to conceive or donate eggs at any time during the study

Study Design

Phase 3
Study Type
Intervention Model
Parallel Assignment
Primary Purpose
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Immediate Switch to DOR/ISL
Participants receiving continuous antiretroviral therapy (ART) will switch to MK-8591A, a fixed dose combination (FDC) of 100 mg doravirine (DOR)/0.75 mg islatravir (ISL) for 96 weeks
  • Drug: DOR/ISL
    A FDC of 100 mg DOR/ 0.75 mg ISL taken in tablet form, orally, once daily
    Other names:
    • MK-8591A
Active Comparator
Baseline Regimen with Delayed Switch to DOR/ISL
Participants receiving continuous ART for 48 weeks will switch to MK-8591A, a FDC of 100 mg DOR/0.75 mg ISL for 48 weeks
  • Drug: DOR/ISL
    A FDC of 100 mg DOR/ 0.75 mg ISL taken in tablet form, orally, once daily
    Other names:
    • MK-8591A

Recruiting Locations

Georgetown University Hospital ( Site 1018)
Washington, District of Columbia 20007
Study Coordinator

More Details

Merck Sharp & Dohme Corp.

Study Contact

Toll Free Number


Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.