Merck's MK-8527 HIV Pill Trial Kicks Off as Stock Ranks 95th in Trading Volume

On July 14, 2025, Merck (MRK) saw a trading volume of $868 million, ranking 95th in the day's stock market activity. The stock price increased by 0.37%.

Merck has announced the initiation of Phase 3 clinical trials for MK-8527, an investigational once-monthly oral pill for HIV pre-exposure prophylaxis (PrEP). The trials, known as EXPrESSIVE-11 and EXPrESSIVE-10, will evaluate the safety and efficacy of MK-8527 compared to the current standard, daily emtricitabine/tenofovir disoproxil fumarate (FTC/TDF).

The EXPrESSIVE-11 trial will begin enrolling participants in August 2025 across 16 countries, focusing on individuals with a higher likelihood of HIV-1 exposure. The EXPrESSIVE-10 trial, targeting women and adolescent girls in sub-Saharan Africa, will commence enrollment in the coming months. Merck will sponsor these trials, with additional support from the Bill & Melinda Gates Foundation.

The decision to advance MK-8527 to Phase 3 trials is based on promising data from a Phase 2 trial, which demonstrated strong safety and pharmacokinetics with no significant adverse effects. MK-8527 is a nucleoside reverse transcriptase translocation inhibitor (NRTTI), acting through multiple mechanisms including delayed chain termination. This positions MK-8527 as a potential long-acting alternative to daily oral PrEP regimens, addressing the global burden of HIV.