How researchers were able to enroll adolescents in landmark HIV trial
Key takeaways:
- A landmark HIV trial found that twice-yearly shots of lenacapavir can prevent HIV in adults and adolescents.
- The FDA will decide by June whether to approve lenacapavir as PrEP.
SAN FRANCISCO — Researchers here described how they were able to safely and ethically enroll adolescents in a landmark trial of a drug that could transform the landscape of HIV prevention.
PURPOSE 1 was a phase 3 trial that showed lenacapavir — the long-acting antiretroviral that is delivered via injection just twice a year — was safe, well-tolerated and 100% effective at preventing HIV among cisgender adolescent girls and young women as young as 16 years old in South Africa and Uganda.
Lenacapavir is already approved in the United States for the treatment of resistant HIV infections, but is not yet approved for prevention. The FDA is scheduled to decide by June 19 whether to approve it as long-acting PrEP.
“Adolescents are often excluded from HIV prevention studies, which can delay their access to new, effective prevention options,” Katherine Gill, MBChB, MPH, senior researcher at the Desmond Tutu Health Foundation in Cape Town, South Africa, said during a press conference at the Conference on Retroviruses and Opportunistic Infections.
“PURPOSE 1 is the first large-scale phase 3 HIV prevention study to intentionally include 16- and 17-year-olds from the beginning, ensuring that they won’t have to wait years for access to prevention,” Gill said.
According to Gill, the current standard practice for most clinical trials is to test safety and efficacy in adults aged 18 years or older before conducting trials in younger populations.
PURPOSE 1 — as well as its follow-up trial, PURPOSE 2 — included participants aged 16 and 17 years, according to Gilead, which manufactures lenacapavir.
To enroll adolescents, Gill said the researchers on PURPOSE 1 engaged with key stakeholders like adolescent medicine experts and received consent from parents at trial sites in South Africa and Uganda.
One innovation, they wrote, was the establishment of a “community consent process led by a site community advisory board, after which waivers for parental consent were issued and adolescents could consent for themselves at that site.”
“In other locales, adolescents who had ever been pregnant were considered emancipated and could consent for themselves,” they explained.
They ended up enrolling 124 participants aged 16 or 17 years, assigning 56 of them to receive lenacapavir. They compared the drug concentrations of adolescent participants with those of adults at weeks 4, 8, 13, 26 and then every 13 weeks.
Gill said that plasma concentrations between the two groups were similar, “which means we can confidently apply what we know about lenacapavir’s pharmacokinetic in adults to younger people,” Gill said.
Also similar between the groups were reports of common adverse events, including injection-site reactions, headache, genitourinary chlamydia and UTI.
“This is important because it supports the early inclusion of adolescents in regulatory approvals and HIV prevention guidelines. But this study is about more than just the data,” Gill said. “It’s also about the path forward. PURPOSE 1 shows us that with the right approach, engaging communities, working with adolescent advisor and collaborating with regulators during the trial design phase, we can successfully include young people in HIV prevention research.”
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Gill K, et al. Abstract 120. Presented at: Conference on Retroviruses and Opportunistic Infections; March 9-12, 2025; San Francisco.
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