Radiopaque Matrix MK-8591 Implant in Participants at Low-Risk for Human Immunodeficiency Virus Type 1 (HIV-1) Infection (MK-8591-043)

A Phase 2a, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of a Radiopaque Matrix MK-8591 Implant in Participants at Low-Risk for HIV-1 Infection

The purpose of this study is to evaluate the safety, tolerability, and pharmacokinetics (PK) of an islatravir (ISL)-eluting implant. Participants will receive an implant placed in the upper arm for approximately 52 weeks with 8 weeks of follow-up in the Base Study. A subset of participants will also receive a second implant for an additional 12 weeks before 8 weeks of follow-up in the Substudy.

Inclusion Criteria:

• Is in good health
• Is confirmed human immunodeficiency virus (HIV)-uninfected
• Is at low risk of HIV infection
• For males, uses contraception in accordance with local regulations regarding contraception use for those participating in clinical trials
• For females, is not pregnant or breastfeeding and one of the following applies:
• Is not a participant of childbearing potential (POCBP)
• Is a POCBP and uses an acceptable contraception method or is abstinent

Exclusion Criteria:

• Has an active diagnosis of hepatitis (B or C) due to any cause
• Has a history of malignancy ≤5 years before signing informed consent
• Has a history or current evidence of any condition that might confound study results or interfere with study participation
• Has a history of keloid in upper arm or presence of tattoo, scar, or other physical finding that could interfere with implant placement (the contralateral arm may be used if the findings are limited to 1 arm)
• Is taking or is expected to take immunosuppressants during the study