Gilead Sciences presented the first clinical data on its investigational once-yearly injectable lenacapavir for HIV prevention at the CROI 2025 conference, with findings also published in *The Lancet*. The Phase 1 study demonstrated that two formulations of intramuscular lenacapavir maintained plasma concentrations above levels associated with HIV prevention efficacy for over 52 weeks. Based on these results, Gilead plans to initiate a Phase 3 trial in the second half of 2025.

The study, which included 40 healthy adults, showed that both formulations of lenacapavir achieved higher median trough concentrations than the twice-yearly subcutaneous formulation used in previous trials. Safety data indicated that the drug was well tolerated, with the most common side effect being mild, temporary injection site pain.

Additional findings presented at CROI included survey results from the PURPOSE 1 trial, showing that most participants preferred twice-yearly injections over daily oral PrEP. Adolescents in the study reported similar pharmacokinetic and safety profiles as adults, with no new HIV infections observed among those receiving lenacapavir.

Lenacapavir, already approved in multiple countries for treating drug-resistant HIV, is being evaluated as a long-acting PrEP option. Gilead's PURPOSE program, the most comprehensive HIV prevention trial series to date, is assessing the drug’s potential in diverse populations. The company remains committed to advancing innovative HIV treatments and prevention strategies.