Lenacapavir Named Science's 2024 Breakthrough of the Year

A Shot in the Arm for HIV Prevention

Science magazine has named lenacapavir its 2024 Breakthrough of the Year, a recognition that signals a potential turning point in the global fight against HIV. The drug, developed by Gilead Sciences, is a twice-yearly injectable that has shown remarkable efficacy in preventing infection. In clinical trials conducted across Africa, lenacapavir reduced the risk of HIV acquisition by up to 96%, a figure that has electrified researchers and public health officials alike.

The accolade, announced on Thursday, places lenacapavir alongside past breakthroughs such as the mRNA COVID-19 vaccines and CRISPR gene editing. Unlike daily oral PrEP (pre-exposure prophylaxis), which requires consistent adherence to be effective, lenacapavir's long-acting formulation means a single injection every six months offers sustained protection. This could be transformative for populations where stigma, logistics, or forgetfulness undermine daily pill regimens.

Why This Drug Stands Apart

Most existing PrEP options are pills taken daily, a routine that many find difficult to maintain. Lenacapavir, originally approved as a treatment for drug-resistant HIV, works by targeting the virus's capsid protein—a novel mechanism that disrupts multiple stages of the viral life cycle. When repurposed for prevention, its long half-life in the body allows for infrequent dosing without compromising efficacy.

In trials involving over 5,000 cisgender women and men who have sex with men, lenacapavir outperformed daily Truvada and Descovy, the current standard of care. Notably, zero infections were recorded among women in the PURPOSE 1 trial who received the drug, an outcome that researchers described as "stunning" in its consistency. The results were so compelling that the trials were halted early so all participants could receive the injection.

Addressing the Adherence Gap

The real-world impact of lenacapavir hinges on its ability to bridge the adherence gap that has long plagued HIV prevention. In many high-burden regions, particularly in sub-Saharan Africa, young women face significant barriers to daily pill use—including stigma, lack of privacy, and competing life pressures. A twice-yearly injection removes these hurdles, offering a discreet and dependable option.

Public health experts argue that this breakthrough arrives at a critical juncture. UNAIDS estimates that 1.3 million new HIV infections occurred globally in 2023, far above the target of fewer than 370,000 by 2025. While existing prevention tools have helped reduce incidence, the pace has been too slow. Lenacapavir's efficacy and durability could accelerate progress, provided it is made accessible and affordable where it is needed most.

Challenges Ahead: Cost and Access

Despite the promise, significant hurdles remain. Gilead has not yet announced a global pricing strategy, and the drug's current list price for treatment in the US is over $40,000 per year—a figure that puts it out of reach for most low- and middle-income countries. Advocacy groups have called for voluntary licensing agreements and generic manufacturing to ensure broad access, echoing past campaigns for HIV drugs.

Regulatory approvals are also pending. The US Food and Drug Administration is expected to review lenacapavir for prevention use in 2025, and other regulators are likely to follow. Even with approval, rollout will require substantial investment in healthcare infrastructure to administer injections and monitor patients.

Science's editors noted that lenacapavir's recognition reflects not just its clinical success, but its potential to reshape prevention strategies worldwide. "This is not merely a new drug," the announcement read. "It is a new paradigm."

What to Watch

The coming months will be decisive. Watch for FDA action on lenacapavir's prevention indication, as well as Gilead's access plans for low-income countries. If pricing and distribution are handled equitably, this breakthrough could mark the beginning of the end of the HIV epidemic. If not, its promise may remain confined to the privileged few.