Last year, Gilead released data showing that an HIV drug, called lenacapavir, could provide virtually complete protection against infection with just a single injection every six months. The drug, now under regulatory review, was greeted as a breakthrough, the closest thing the field has ever had to a vaccine.
On Tuesday, Gilead published early data suggesting a new formulation of the drug could be used to prevent infection with just a single shot every year.
“The results are extremely promising,” said Jonathan Li, director of the Harvard University Center for AIDS Research Clinical Core, in an email. “The current lenacapavir twice-yearly formulation is poised to change HIV prevention as we know it and decreasing the dosing to yearly will only improve adherence.”
The study, published in The Lancet, did not actually test efficacy in preventing HIV. Instead, investigators injected two groups of 20 volunteers with two different proposed formulations and took regular blood samples to measure the levels of drug that remained in the blood.
Then they compared those levels to drug levels from volunteers in the two large trials. Sure enough, volunteers who received either new formulation had higher levels of drug in their bloodstream for 56 weeks than volunteers receiving once-every-six-month injections. That suggests the new medicine should provide equal protection.
Howard Gendelman, who develops long-acting antiretrovirals, said the data “shatter a glass ceiling” and could pave a path toward once-yearly medicines for both HIV and other diseases.
Of course, Gilead will have to prove it in a much larger study. Jared Baeten, Gilead’s senior vice president of clinical development and virology, said in an interview the company was still reviewing the data to select an optimal formulation and dose.
The company plans to begin a Phase 3 trial of the once-a-year version this year, but it hasn’t yet determined what that study will look like. Baeten demurred on details but suggested Gilead may be able to run a large single-arm trial, in which they give volunteers the once-a-year treatment, before monitoring them to assure that the formulation is safe and that drug levels remain high enough to offer protection for over a year.
“We’re in the process of [figuring out] that design right now,” he said.
Gilead will do so as the HIV prevention field faces an uncertain future. Lenacapavir has been broadly hailed as a revolution in pre-exposure prophylaxis, or PrEP, offering the potential to replace daily pills that have not managed to bring the epidemic to heel. But PrEP has historically been distributed around the world largely through PEPFAR, the George W. Bush-era program for combatting HIV and AIDS around the globe.
That program has now been largely dismantled by the Trump administration. A Gilead spokesperson declined to comment on what cuts to PEPFAR will mean for the company’s plans or lenacapavir’s eventual reach.
“It’s one of those things that’s just changing so quickly,” she said. “Obviously, we’re watching it closely, but right now, we’re really focused on the studies and the science and the data for the patients to get them into their hands.”