This preventive drug could be a 'game changer' in ending the HIV epidemic

Can we eliminate the HIV epidemic?

It’s a question that dates back to the start of the epidemic in the 1980s. With 1.3 million new infections a year, the epidemic continues … and the world is not on track to meet the ambitious U.N. goal of ending HIV/AIDS by 2030.

But now there’s rising optimism among leading infectious disease experts after the latest groundbreaking clinical trial results for a drug called lenacapavir which have shown it to be capable of virtually eliminating new HIV infections through sex.

PURPOSE 2, the name for the latest trial sponsored by Gilead Science, the California-based maker of lenacapavir, found the drug to be 96% effective in preventing HIV infections in the newly released results of a clinical trial of more than 3,200 cisgender men, transgender men, transgender women and gender non-binary individuals who have sex with partners assigned male at birth. The study was conducted across sites in Argentina, Brazil, Mexico, Peru, South Africa, Thailand and the United States.

These results follow equally dramatic findings from a previous lenacapavir trial called PURPOSE 1 which followed 5,300 cisgender women in South Africa and Uganda. In news which headlined July’s AIDS 2024 conference in Munich, early results indicated 100% efficacy, after Gilead Sciences revealed that not a single woman who had received the drug since the trial began in August 2021, had contracted HIV.

Ethel Weld , an assistant professor of medicine at the Johns Hopkins University School of Medicine, described both sets of results as ‘a thrilling game changer for HIV prevention.’

In particular, lenacapavir which is administered via a twice-yearly injection, represents a dramatic new alternative to the current standard of care for HIV prevention: taking a pill called Truvada every day. While this type of drug, called pre-exposure prophylaxis (PrEP), has also been shown to be 99% effective in blocking HIV infections from sex in clinical trials, this is not necessarily the case in the real world.

People don’t always take their pills. In a study in South Africa, women said they felt there was a stigma to the pill -- a sexual partner might assume they’re taking it because they already have HIV or because they have other partners. Research has also highlighted significant barriers in taking daily oral PrEP among men who have sex with men, ranging from access to the drug, inconvenience, and perceptions that it is unnecessary. One study showed oral PrEP effectiveness to be as low as 26% in certain populations -- men under age 30, for example.

Weld points out that in both the PURPOSE 1 and PURPOSE 2 trials, it was notable that the participants randomized to receive daily oral PrEP instead of lenacapavir, showed low adherence to the medication.

“The burden of taking daily medicine varies for each individual and may well be perceived as an even greater burden for healthy people who feel fine,” says Weld. “The finding that twice yearly injections have high efficacy in preventing HIV, lowers the amount that an individual has to do over the course of a lifetime to protect themselves. It puts lenacapavir much closer to the domain of other preventive paradigms such as vaccination.”

A potential 'game-changer'

Advocacy groups have also expressed great enthusiasm. “Lenacapavir would be “a real game-changer,” particularly for people facing stigma and discrimination in low- and middle-income countries,” read a statement by People’s Medicines Alliance -- a global coalition of more than 100 organizations that span 33 countries and that advocate for making medications more accessible.

Cécile Tremblay, a HIV researcher at the University of Montréal, highlighted the drug’s potential to tackle the epidemic in sub-Saharan Africa where the disease burden is greatest. Despite accounting for 10% of the world’s population, sub-Saharan Africans comprise two-thirds of people living with HIV -- 25.7 million out of 38.4 million. Every week, about 4,000 teen girls and young women in Africa are newly infected with HIV.

“Not only is lenacapavir extremely efficacious but the efficacy has been shown in a population of women in sub-Saharan Africa where the epidemic is the greatest, and oral PrEP has not performed as well due to stigma and discrimination,” says Tremblay.

Next steps

Lenacapavir is not a new drug. It’s been approved by the FDA in the United States for multi-drug resistant HIV treatment since 2022 . But PURPOSE 1 and PURPOSE 2 are the first clinical trials to test it for HIV prevention.

According to Gilead Sciences, the data from the two trials will now be used to support a series of global regulatory filings which will begin by the end of 2024, with the aim of launching lenacapavir onto the market at some point in 2025.

Yet any eventual approval and widespread use would come with challenges. According to an analysis presented at the 24th International AIDS Conference (AIDS 2022), PrEP medications would need to cost less than $54 a year per patient for South Africa, for example, to be able to afford them. Lenacapavir’s cost as HIV treatment in the United States in 2023 was $42,250 per new patient per year. Oral PrEP options, on the other hand, can cost less than $4 a month.

Given the drug’s potential, Tremblay says that it is critical for access to be as widespread as possible. “The infrastructure needs to be in place to reach at-risk populations and make sure they can access it,” she says. “If everyone at risk could receive this prophylaxis, within a few years it could alter the course of the epidemic. When you substantially decrease the transmission rate, then the epidemic can wane down.”

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