Groundbreaking new HIV prevention method could soon revolutionize how we fight the virus—offering a single injection that lasts over a year. Data from an early-phase trial reveals that lenacapavir, an experimental drug, remains in the body for up to 56 weeks, opening the door to a potential once-a-year solution for pre-exposure prophylaxis (PrEP).
“This is a hopeful step, and the study data are positive,” says María Velasco, spokesperson for the Spanish Society of Infectious Diseases and Clinical Microbiology (Seimc). She highlights the promising results of this phase 1 trial, which evaluated the effectiveness and safety of an intramuscular injection to create a long-lasting barrier against HIV infection.
Published in The Lancet and presented at the Conference on Retroviruses and Opportunistic Infections (CROI), the study demonstrates that medication concentrations remain in the body well beyond a year.
A Major Step Forward in HIV Prevention
Regulatory agencies in Europe are currently reviewing a semi-annual version of lenacapavir for approval, while the U.S. FDA may grant it an accelerated review. The drug, developed by Gilead, has already earned recognition as one of the most significant medical breakthroughs of the year by Science magazine.
PrEP is a preventive treatment for individuals at risk of HIV exposure, blocking the virus from entering and replicating in human cells. Currently, PrEP is available as a daily pill, which, when taken consistently, reduces the risk of infection by more than 90%. Injectable PrEP, administered every six months, boasts nearly 100% efficacy.
However, accessibility remains a challenge. In 2023, only 3.5 million out of 21.2 million people who could benefit from PrEP were receiving it. Barriers such as stigma, healthcare access, adherence issues, and medication costs limit its reach.
Velasco emphasizes that neither PrEP nor the new injection is a vaccine. “There is currently no HIV vaccine available. But long-acting medications like this are especially useful for groups where daily pills may not be effective, such as women in vulnerable situations,” she explains. “We are on the brink of a new era in HIV prevention.”
What Did the New Trial Reveal?
In the study, 40 HIV-negative participants aged 18 to 55 received a single dose of one of two lenacapavir formulations. Researchers monitored them for up to 56 weeks, evaluating how the drug moved through their bodies and assessing its safety.
The results? The drug was well tolerated, with the most common side effect being mild pain at the injection site. “We need to see if it behaves the same way in phase 2 trials, especially regarding tolerability,” says Velasco.
Importantly, no significant safety issues were identified. After 56 weeks, lenacapavir remained in the bloodstream at levels exceeding those required for effectiveness, based on previous phase 3 trials of the twice-a-year subcutaneous version of the drug.
“This study compares its performance with the Purpose 1 and 2 trials, which evaluated the drug’s semi-annual effectiveness,” Velasco notes.
While the phase 1 study focused on safety and drug retention rather than efficacy in preventing HIV, researchers say more trials—including those with more diverse participant groups—are needed to confirm its full potential. If successful, this innovation could mark a game-changing shift in the fight against HIV.
