Skip to content

The highs and lows of great science but enduring inequities in both research and rollout were front and center at the 2024 Conference of Retroviruses and Opportunistic Infections (CROI). Sessions focused on the power of choice in expanding the impact of HIV prevention, and lessons to be learned from efforts to rollout new options from three different continents. Read on for key highlights!

Even longer long-acting PrEP products?

A longer-acting injectable cabotegravir for prevention (injectable CAB) has made it through a phase 1 safety and tolerability study. ViiV, the maker of the currently approved injectable cabotegravir, presented findings on a new formulation that could double the time between intramuscular jabs, from two to four months, potentially making it a three-dose annual intervention, instead of six doses.

Merck also presented data on the safety and pharmacokinetic profile of MK-8527, a product that they are hoping to develop as a monthly pill to prevent HIV. They reported the dose was safe, well-tolerated and sufficient to show anti-viral activity against HIV. The product is currently in a phase 2 trial in several countries globally; and later phase studies would be needed to demonstrate efficacy. Check out our prevention product timeline here.

Evidence for making the most of prevention tools and the power of choice!

Studies from three different continents delivered the message: enriched programs that support coverage and choice of prevention options will yield dramatic results.

PEPFAR representatives pledged to take the findings of the SEARCH Dynamic Choice study into their programming decisions. Why? Just look at these results: Conducted in Kenya and Uganda, the study offered oral PrEP, PEP or injectable cabotegravir to both men and women, and an option to switch products. Prevention services were person-centered, including access to a clinician by phone at any time, clinic and community access to services, and counseling to develop personalized adherence plans. Coverage among study participants increased to 69.7% compared to 13% in the standard of care. Among people who self-reported HIV risk, coverage was 76%. Of the 56% who chose injectable CAB, 42% were not on any prevention product in the prior month. And perhaps most intriguing of all, 28% of participants used two different products during the study and the study arm ended with zero incidence of HIV compared to 1.8% in the control group—these numbers show why adding to the method mix expands the number of people who continue with prevention, even as their needs change. “CAB-LA is not simply replacing oral PrEP. It’s expanding the pie,” said Moses Kamya of Kampala’s Makerere University, who presented these data.

Data from the INSIGHT cohort looked at PrEP uptake and continued use among more than 3,000 adolescent girls and young women in six African countries over six months. Participants who were shown test results measuring protective levels of PrEP in their bodies had higher adherence. The results: uptake was greater than 90%, at least 64% showed evidence of recent use. Investigators reported that “real time feedback” from these tests motivated adherence.

In the US, a study conducted by Emory University suggests a direct link between population PrEP coverage and decreased HIV incidence. Between 2012-2021, PrEP coverage in the US ranged from 3.8% in West Virginia to 22% in New York, and rates of new diagnoses fell in association with increased coverage by state.

Data from Australia analyzed HIV incidence among all people prescribed PrEP in Australia’s national PrEP program by tracking government subsidized PrEP prescriptions and antiretroviral therapy (ART) between 2018 and 2023. ART was used as a proxy for HIV acquisition, because both testing and treatment among PLHIV are high across the country. The data showed that low PrEP usage among gay men and other men who have sex with men, along with younger age and hepatitis C treatment was predictive of HIV incidence. Nicholas Medland who presented the data said “the overall incidence rate is low. As long as you can get PrEP out the door, it works at the population level.”

The Deliver Study investigating efficacy of the dapivirine vaginal ring (DVR) among pregnant and lactating people (PLP) provided data from people in the second trimester of pregnancy. Building on earlier findings in later stages of pregnancy, investigators reported no increased rate of adverse outcomes compared to pregnancy outcomes in the community, and that “data support using DVR” as an HIV prevention option for PLP.  At this time, 11 countries have approved DVR, but this data is needed for regulators to approve its use for people who are pregnant. See our PrEP tracker for the latest on DVR initiations, regulatory approvals and more.

The promise and pitfalls of biomedical prevention

CROI ended on a powerful call to action to better understand the options that exist today and solve the problems of access. At one of the final sessions, Promise and Pitfalls of Biomedical Prevention: Beyond Phase III, three presentations put a spotlight on the status of approved products and the need for choice.

Rupa Patel from the CDC took attendees through a maze of access barriers facing injectable cabotegravir – from insurance to personnel issues – in the U.S.— the only country with a commercial market at this time. Rollout in other countries is just beginning with initial, limited supply (1.2 million doses for low- and middle-income countries through 2025). Still, it’s moving faster than oral PrEP, where it took more than three years after FDA approval before a single African country approval. In contrast, just two years post-FDA approval, seven African countries have approved injectable cabotegravir, with several others pending. (Check out AVAC’s PrEP tracker for details.) But these gains are still too slow. Patel concluded by offering future solutions, including accelerating the entry of generics in the market, pursuing scientific and regulatory efforts in parallel, and expanding models that build up community delivery of HIV services.

Leila Mansoor laid out the complex journey of the dapivirine vaginal ring (DVR). Initial efficacy trials reported approximately 30% efficacy, but Mansoor presented additional exploratory analyses that estimated risk-reduction could actually be 75-91% with high adherence. In addition, the REACH study showed that when young women are offered high-quality counseling and choice, it results in high adherence; the young women in REACH preferred DVR to oral PrEP by 2 to 1. Data presented earlier this week expanded the evidence of the DVR’s safety for people who are pregnant and lactating. And 11 countries have approved it. Mansoor’s call to action: women need and want DVR as an option, and it is now being added to the SEARCH study.

Jenelle Stewart then faced down the doubters of event-driven PrEP by marshalling evidence that the intervention works in men and may work in women. Stewart referenced a JAMA article by Jeanne Marrazzo just last week that high-but-imperfect adherence (4-6 pills per week) was protective for women. She followed with a clear call for event-driven PrEP for women without needing to go through another large, randomized trial. Stewart made several other provocative points, concluding that event-driven PrEP is desired by some, effective, and should be incorporated in public health guidelines.

In addition, results of a Phase II study of weekly oral islatravir and lenacapavir showed safety and non-inferiority of viral suppression to daily ART. Take home message: this product has the potential to become the first weekly oral regimen for treatment.