Voluntarily terminated due to benefit/risk assessment

This study will evaluate whether oral islatravir (ISL) is effective in preventing Human Immunodeficiency Virus Type 1 (HIV-1) infection in women at high-risk for HIV-1 infection. The study will compare oral ISL taken once a month with standard-of-care medication for prevention of HIV-1 infection, emtricitabine/tenofovir disoproxil (FTC/TDF), taken once per day. The primary hypothesis is that oral ISL is more effective than FTC/TDF at reducing the incidence rate per year of confirmed HIV-1 infections.

Based on laboratory findings of decreased lymphocyte and CD4+ T-cell counts across the islatravir program, dosing of blinded study intervention was halted on 13-Dec-2021 and screening and randomization of new participants was ended. Blinded assessments conducted prior to this date are designated as Study Part 1. During Study Part 2, participants from Part 1 have the option to receive daily open-label FTC/TDF while continuing in the study for safety monitoring. Study Part 3 was added to unblind each participant's Part 1 study intervention assignment, continue participants on FTC/TDF, and monitor safety.

Inclusion Criteria:

• Confirmed HIV-uninfected based on negative HIV-1/HIV-2 test results before randomization.
• Sexually active (vaginal and/or anal sex) with a male sexual partner in the 30 days prior to screening.
• High risk for HIV-1 infection.
• Not pregnant or breastfeeding, and one of the following conditions applies: Not a woman of childbearing potential (WOCBP) or is a WOCBP and is using an acceptable contraceptive method during the intervention period and for at least 42 days after the last dose.
• A WOCBP must have a negative pregnancy test within 24 hours prior to the first dose of study intervention.

Exclusion Criteria:

• Hypersensitivity or other contraindication to any of the components of the study interventions as determined by the investigator.
• Findings of chronic hepatitis B virus (HBV) infection or past HBV.
• Current or chronic history of liver disease.
• History of malignancy within 5 years of screening except for adequately-treated basal cell or squamous cell skin cancer, or in situ cervical cancer.
• Past or current use of cabotegravir, lenacapavir, or any other long-acting HIV prevention product.
• Currently participating in or has participated in an interventional clinical study with an investigational compound or device, within 30 days prior to Day 1.
• Expecting to conceive or donate eggs at any time during the study.

Assigned female sex at birth and is cisgender

https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

In Study Part 1, a double-blinding technique with in-house blinding will be used. ISL and FTC/TDF will be packaged identically relative to their matching placebos so that blind is maintained. The participant, the investigator, and Sponsor personnel or delegate(s) who are involved in the study intervention administration or clinical evaluation of the participants are unaware of the intervention assignments.

In Study Part 2, sponsor personnel not directly involved with blinded safety monitoring will be unblinded to participants' randomized study intervention in Part 1.

In Study Part 3, participants, investigators, and all Sponsor personnel will be unblinded to the participants' original randomized study intervention group.