There were no cases of HIV in over 2,000 cisgender women who received a twice-a-year preventive HIV injection developed by Gilead as part of a Phase 3 clinical trial.
The data, announced Thursday morning, led an independent data review group to recommend that the company stop the blinded study and offer the prevention treatment to all participants.
The PURPOSE 1 study showed that there was a lower incidence of HIV cases with the twice-a-year injection of lenacapavir compared to data on background HIV incidence, as well as compared to Truvada, Gilead’s daily pill that’s used for prevention.
“It’ll be a game changer for people who are at high risk, as long as implementing it doesn’t become a huge problem,” said Rachel Presti, a professor of infectious diseases at the Washington University School of Medicine in St. Louis. She was not involved in the study.
The results add to data that show long-acting antivirals may be more effective at preventing HIV than daily pills. GSK found in Phase 3 trials that its long-acting injectable Apretude, given once every other month, was also better than a daily pill at preventing HIV. Apretude was approved for pre-exposure prophylaxis (PrEP) in 2021.
Gilead’s Phase 3 study enrolled over 5,300 cisgender women and girls ages 16 to 25 in South Africa and Uganda and split them into three arms. One arm received the lenacapavir injection twice a year; another arm received Truvada, a two-drug daily antiviral pill; and a third arm received Gilead’s Descovy. Like Truvada, Descovy is a two-drug daily pill, but comes potentially with fewer side effects.
When Descovy was first approved for prevention, it wasn’t approved for cisgender women because Gilead didn’t include them in clinical trials. Gilead markets lenacapavir as Sunlenca as a treatment for people with multi-drug resistant HIV. It was approved in the US in late 2022.
In the newest study, in the lenacapavir arm, there were zero cases of HIV. In the Truvada arm, there were 16 cases of HIV among 1,068 women. The lenacapavir results show an improvement over both HIV incidence with Truvada and background HIV incidence of 2.41 cases per 100 person-years, which was the primary endpoint of the study.
Jared Baeten“This is a potentially quite powerful prevention choice for people who would want to get something that would be private, discreet, and that they would not have to maintain adherence to during that entire period between the injections,” Gilead’s HIV franchise head Jared Baeten said.
In the Descovy group, there were 39 cases among the 2,136 women, and the result from that arm of the study was not statistically superior compared to background HIV incidence.
“It’s another reflection of the fact that, for some people, it’s just really hard to take pills — to remember to take them, to get around all the stigma of other people seeing you take them,” Presti said.
“Think about how hard it is for young women to get on birth control pills because the assumption is then you’re having sex and everyone gets very judgmental about it,” she added. “If you’re taking PrEP, everyone assumes you’re having high-risk sex, and/or they assume that you’re infected because it’s an HIV medicine.”
Gilead is running a complementary study called PURPOSE 2 with cisgender men, transgender men and women, and nonbinary individuals that is expected to read out by early next year. The pharma company then plans to take results from both studies to regulators around the globe to seek approval for lenacapavir as an HIV prevention drug.
Presti applauded how Gilead’s Phase 3 study with cisgender women in South Africa and Uganda read out first. “Usually it’s the other way round,” she said. “Usually, these things get proven in men who have sex with men, in high-income places. So I think it’s fantastic to see this come up first.”
Editor’s note: This story was corrected to reflect that the brand name of GSK/ViiV’s long-acting injectable for HIV prevention is Apretude. A previous version stated it was Cabenuva, which is the brand name of its long-acting HIV treatment.