HIV remains a global health crisis, infecting more than 1 million people annually. Although research has advanced to treat people who become infected, a vaccine to protect people from infection remains elusive. However, a new injectable drug from Gilead Sciences, lenacapavir, is reshaping the fight against the virus. Unlike pre-exposure prophylaxis (PrEP) pills, which must be taken daily, a single shot of lenacapavir protects against HIV for six months. Clinical trials have shown impressive results. In South Africa and Uganda, a study involving adolescent girls and young women found zero infections among those who received the injection. Another global trial reported a 99.9% efficacy rate among gender-diverse people who have sex with men. “You don’t see data like this every day,” said Mitchell Warren of AVAC, a nonprofit focused on HIV prevention.
Easing Pre-Exposure Prophylaxis (PrEP) Compliance
PrEP has proven effective in reducing new infections, especially in high-risk populations. However, adherence to daily pills has been a challenge, particularly in resource-limited settings. With its six-month dosing schedule, lenacapavir could dramatically curb infection rates if distributed widely in at-risk populations. According to Linda-Gail Bekker, an infectious disease specialist at the University of Cape Town, who led one of the trials, “It has the potential, if we can do it right, which means going big and getting it out there.”
The drug’s success stems from a breakthrough in understanding HIV’s capsid protein. Lenacapavir targets this protective shell, stiffening it and disrupting the virus’s ability to replicate. Unlike earlier drugs that targeted viral enzymes, this approach exploits capsid’s unique vulnerabilities.
The Capsid Connection
A capsid is a protein shell that protects a virus’ genetic material. Research in the 1990s had cast doubt on the capsid as a viable drug target. As reported recently, Capsida Biotherapeutics is developing a gene therapy for developmental and epileptic encephalopathy delivered by an engineered capsid platform. Research has revealed that the capsid structure—a flexible lattice of molecules—plays a critical role in HIV’s lifecycle. By stabilizing this structure, lenacapavir halts the virus in its tracks. Researchers at Gilead overcame challenges in making the drug absorbable by developing a long-acting injectable form. This innovation turned the drug’s previous weaknesses into strengths, allowing it to stay effective in the body for months.
Challenges to Global Access
Lenacapavir is already available as a “salvage” treatment for patients resistant to other HIV drugs. However, its potential as PrEP hinges on access and affordability. Regulatory approval isn’t expected until mid-2025, and the price remains undisclosed. However, Gilead has partnered with six generic manufacturers to supply low-cost versions to 120 developing countries.
Barriers extend beyond cost. Resource-strapped healthcare systems, logistical hurdles, and social stigma could impede widespread adoption. Moreover, people must be willing to commit to biannual injections, a shift from the daily regimen of oral PrEP.
Hope for the Future
Gilead is continuing to refine lenacapavir and has announced that it will begin Phase III trials of a formulation that would only need to be administered annually.
At the same time, Jeanne Marrazzo, head of the U.S. National Institute of Allergy and Infectious Diseases, stresses that a vaccine remains essential. While she is hopeful that lenacapavir could “dramatically reduce HIV incidence in our most challenging areas,” she also said, “we must continue to search for an intervention that will create durable individual immunity if we really want to end HIV.” Vaccines, once developed, could be universally administered and provide long-term immunity, a goal no current HIV/AIDS drug can achieve.
Even so, lenacapavir represents a leap forward. It offers hope to millions and builds on decades of biomedical advancements. If deployed effectively, it could bring the world closer to turning HIV/AIDS into a rare and manageable condition.
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