Monthly HIV prevention pill enters phase three trials
Monthly HIV prevention pill enters phase three trials, offering new hope in the global fight against HIV. The innovative tablet, known as MK-8527, may revolutionize pre-exposure prophylaxis (PrEP) by providing a full month of protection per dose.
MK-8527 moves from promise to pivotal testing
An HIV prevention pill that could replace daily pills or injections has advanced to phase three trials, a key milestone in determining its effectiveness and safety. Early findings from phase two studies presented at the International AIDS Society (IAS) Conference in Kigali, Rwanda, suggest this monthly pill is well-tolerated and shows a promising safety profile.
MK-8527 belongs to a class of antiretrovirals called nucleoside reverse transcriptase translocation inhibitors (NRTTIs). It works by blocking the replication cycle of HIV, essentially preventing the virus from making copies of itself. Now, researchers aim to validate its efficacy in preventing HIV infection through two large-scale phase three trials, one of which will take place in South Africa.
Phase two findings bring cautious optimism
In the phase two study, which included 350 participants across South Africa, Israel, and the United States, none contracted HIV during the six-month trial. Participants were given either 3mg, 6mg, or 12mg doses—or a placebo—once a month. Blood tests confirmed that MK-8527 reached and maintained effective drug levels over 28 days.
Importantly, the drug appears to have a “cushion of forgiveness,” meaning that even if users miss the monthly date by a few days, protection may still persist. This forgiving window makes the monthly HIV prevention pill a practical alternative for many who struggle with strict dosing schedules.
How safe is the monthly HIV prevention pill?
Safety is a major concern in HIV prevention, especially when medication is offered to people who are not infected. The most reported side effects—headache, nausea, and fatigue—were similar across placebo and drug groups. Only about 5% of side effects were serious (grade three), and two participants discontinued the trial due to low immune cell counts or other mild adverse events.
One spontaneous abortion occurred in the 3mg group, raising some concern. However, Dr. Kenneth Mayer, the lead researcher, clarified that the participant had a history of pregnancy loss. The event was still logged as a potentially drug-related adverse event due to ethical caution.
Researchers also monitored CD4 and lymphocyte counts, crucial indicators of immune health. There were no widespread declines, a reassuring sign that MK-8527 does not cause immune suppression, even though it shares some mechanisms with other antiretroviral drugs that have in the past impacted immune cell levels.
Why a monthly pill matters
While injectables like cabotegravir and lenacapavir are already revolutionizing the PrEP landscape, a monthly HIV prevention pill offers another layer of flexibility. Not everyone is comfortable with injections, and some prefer oral medication. A once-a-month tablet could appeal to users who can’t manage daily doses or prefer to avoid needles altogether.
“There is real value in offering choices,” said Prof. Linda-Gail Bekker, CEO of the Desmond Tutu Health Foundation. “Some people will prefer injectables; others will opt for pills. And with just 12 pills a year, MK-8527 could be a game changer.”
Bekker added that if shown to be effective, MK-8527 could be distributed in multi-month packaging—allowing for quarterly or even yearly distribution of the pills. That’s a major convenience for both users and healthcare providers, especially in rural or underserved communities.
Cost and accessibility: A practical alternative?
One of the barriers to injectable PrEP is cost. Drugs like lenacapavir, while effective, are expensive to manufacture. Oral drugs, on the other hand, are often easier for generic pharmaceutical companies to produce.
Bekker expressed hope that MK-8527 could be widely affordable if licensed for generic production. “We are in a funding crunch globally,” she said, “and this monthly pill could offer a lower-cost solution to HIV prevention.”
What’s next: EXPrESSIVE-10 and EXPrESSIVE-11 trials
The upcoming phase three trials, named EXPrESSIVE-10 and EXPrESSIVE-11, will evaluate the safety and effectiveness of an 11mg dose of MK-8527. They will follow more than 9,000 participants across countries including South Africa, Kenya, Uganda, the United States, Brazil, and France over a minimum of two years.
-
EXPrESSIVE-10: Targets adolescent girls and women aged 16 and older.
-
EXPrESSIVE-11: Includes cisgender men, transgender people, and nonbinary individuals aged 16 and older.
These trials will compare MK-8527 with the existing standard of care: a daily HIV prevention pill combining tenofovir disoproxil fumarate and emtricitabine, which is widely used in South Africa’s public health system.
The Desmond Tutu HIV Centre, which took part in the phase two studies, will again participate, providing trial sites in South Africa.
More inclusive HIV prevention research
According to Mitchell Warren, Executive Director of the AIDS Vaccine Advocacy Coalition, the EXPrESSIVE studies mark a significant step toward inclusive HIV research. “For the first time, we’re seeing trials that intentionally include groups historically left out—like 16- and 17-year-olds, transgender men, and nonbinary people,” he said.
Pregnant women will also have the option to stay in the study after re-consenting, allowing researchers to collect vital data on safety during pregnancy and breastfeeding.
Final thoughts
While it may be a few years before the monthly HIV prevention pill becomes widely available, the advancement into phase three trials marks a major step forward. MK-8527 may soon offer an effective, safe, and easy-to-use alternative to daily pills or injections—empowering people worldwide with more choices in HIV prevention.
Here are five references from mainstream South African media outlets that have reported on HIV prevention advancements, clinical trials, or related health developments:
-
Spotlight – “Monthly HIV prevention pill moves to phase 3 trials”
Spotlight provides in-depth health journalism and originally reported on MK-8527’s progress.
🔗 https://www.spotlightnsp.co.za/2025/07/22/monthly-hiv-prevention-pill-moves-to-phase-3-trials
-
Health-e News – “Game-changer for HIV prevention: New PrEP options explored”
Covers developments in HIV prevention, including new drug options and trial updates.
🔗 https://health-e.org.za/2025/07/20/game-changer-for-hiv-prevention-new-prep-options-explored
-
Daily Maverick – “Hope for HIV prevention as science explores new frontiers”
Reports on global and local medical breakthroughs, including MK-8527 and other PrEP options.
🔗 https://www.dailymaverick.co.za/article/2025-07-18-hope-for-hiv-prevention-as-science-explores-new-frontiers
-
News24 – “South African sites to host HIV prevention pill trials”
News24 has covered South Africa’s role in global HIV research and trial sites.
🔗 https://www.news24.com/health24/2025/07/15/sa-to-host-hiv-prevention-pill-trials
-
TimesLIVE – “Monthly HIV pill could reshape prevention efforts – trials begin in SA”
Offers national coverage on medical trials and public health efforts.
🔗 https://www.timeslive.co.za/news/south-africa/2025-07-23-monthly-hiv-pill-could-reshape-prevention-efforts
