touchINFECTIOUS DISEASES coverage of IAS 2025
Prof. Kenneth H. Mayer presented encouraging findings on the safety and pharmacokinetics of MK-8527, a once-monthly oral antiretroviral being developed for HIV pre-exposure prophylaxis (PrEP) (NCT07044297). The Phase 2 study evaluated MK-8527 in individuals at low risk of HIV and laid the groundwork for forthcoming efficacy trials. Prof. Kenneth Mayer is Professor of Medicine at Harvard Medical School, Boston, MA, USA, and Medical Research Director at Fenway Health, he shares insights on the study results and their broader significance. He discusses how MK-8527 could expand HIV prevention options, particularly for those who may not prefer daily pills or injections, and outlines the next steps in clinical development.
The abstract “Safety and pharmacokinetics of MK-8527 oral once-monthly: a phase 2 study in adults at low risk of HIV-1 exposure” was presented at IAS 2025, Kigali, Rwanda, 13–17 July 2025.
In this Phase 2 study, 350 individuals at low risk for HIV were randomized to receive either 3, 6, or 12 mg of MK-8527, or placebo, taking one pill on a monthly basis for six months. MK-8527 was found to be generally well-tolerated, with side effect levels that were comparable between dosing groups and not significantly different from the placebo group.
Blood levels were measured to determine drug concentrations one hour after administration, one day later, and one month later, and participants were followed until eight weeks after their last dose. Pharmacologists were able to construct concentration-time curves to determine how long drug levels remained above estimated protective values—extrapolated from animal studies and pharmacokinetic measurements of other PrEP agents.
The most common side effects were headache, nausea, and fatigue, each reported in less than 5% of participants, and the prevalence did not differ between the MK-8527 groups and the placebo group. We also monitored for low lymphocyte counts, since this had been observed with islatravir, which shares the same mechanism of action as MK-8527, but lymphocyte reductions were rare and did not differ between the study groups.
Overall, the safety pattern of MK-8527 was comparable to, or better than, already approved PrEP medications.
This was a Phase II study designed to evaluate safety, tolerability, and pharmacokinetics in low-risk individuals. These findings were necessary to inform the design and development of Phase III trials, which will assess efficacy in high-risk populations. Those studies are scheduled to begin in the coming months, and if successful, will support regulatory approvals.
A once-monthly pill could be a game changer. Some people have difficulty taking a daily pill and do not want injections. If found to be efficacious, MK‑8527 could serve as an important additional option to increase PrEP uptake and adherence, ultimately helping to decrease the rate of new HIV infections.
The next set of studies will enrol cisgender women in several countries in Africa, as well as high-risk cisgender men, transgender, and non-binary people who have sex with men in multiple countries across the Americas, Asia, Europe, and Africa.
The rollout of long-acting lenacapavir and cabotegravir in low- and middle-income countries, and the progress of MK‑8527 are among the most exciting developments. These advances reflect a growing toolkit of prevention options tailored to the needs and preferences of diverse populations.
Further content in HIV
This content has been developed independently by Touch Medical Media for touchINFECTIOUS DISEASES. It is not affiliated with the International AIDS Society (IAS). Views expressed are the speaker’s own and do not necessarily reflect the views of Touch Medical Media.
Abstract: Mayer K, Kotze P, Lombaard J et al. Safety and pharmacokinetics of MK-8527 oral once-monthly: a phase 2 study in adults at low risk of HIV-1 exposure. Abstract #OAS0106LB. Presented at: IAS 2025, Kigali, Rwanda, 17 July: OAC0503.
Editor: Katey Gabrysch, Editorial Director.
Disclosures: This short article was prepared by touchINFECTIOUS DISEASES in collaboration with Kenneth Mayer. touchINFECTIOUS DISEASES utilize AI as an editorial tool (ChatGPT (GPT-4o) [Large language model]. https://chat.openai.com/chat). The content was developed and edited by human editors. No fees or funding were associated with its publication.
Kenneth Mayer has received Grant/Research Support from Gilead, Merck and ViiV Healthcare and is on the advisory board for Gilead, Merck and ViiV Healthcare.
Cite: Kenneth Mayer. MK-8527 shows promise as once-monthly oral PrEP option for HIV Prevention. 04 August 2025.
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