Merck & Co. Inc. has announced the initiation of the EXPrESSIVE Phase 3 clinical trials to evaluate the safety and efficacy of MK-8527, an investigational once-monthly oral nucleoside reverse transcriptase translocation inhibitor for HIV pre-exposure prophylaxis (PrEP). The trials are being conducted in collaboration with the Gates Foundation. The EXPrESSIVE-10 trial will focus on women and adolescent girls in sub-Saharan Africa, while the EXPrESSIVE-11 trial will target individuals with a greater likelihood of HIV-1 exposure in 16 countries, with enrollment scheduled to begin in August 2025. This decision follows a Phase 2 trial involving 350 participants, which demonstrated favorable safety and pharmacokinetic profiles of MK-8527. Results from this Phase 2 trial were presented during the 13th International AIDS Society Conference on HIV Science in Kigali, Rwanda.