Weekly HIV Pill as Effective as Daily Treatment in ISLEND-1 Trial

For millions of people living with HIV, the daily ritual of medication is more than a health requirement; it is a constant reminder of their condition. A new once-weekly oral regimen aims to break that cycle, offering a way to maintain viral suppression without the burden of a 365-day-a-year pill schedule.

ISLEND-1 Trial: Comparing Weekly and Daily Regimens

The Phase III ISLEND-1 trial involved 607 adults across 12 countries and 106 clinical sites. Researchers tested a combination of two long-acting antiretroviral drugs, islatravir and lenacapavir, delivered in a single weekly pill. This was measured against Biktarvy, a gold-standard three-drug combination taken once daily.

The results, published on July 29 in The New England Journal of Medicine, showed that the weekly regimen was noninferior to the daily treatment. In the weekly treatment arm, no participants had a viral load of 50 copies per milliliter or higher at the 48-week mark. In contrast, one participant on the daily regimen exceeded that threshold.

Metric	Once-Weekly (Islatravir-Lenacapavir)	Once-Daily (Biktarvy)
Viral Suppression Rate	>93%	>93%
Virologic Failure	0 participants	0 participants
Medication Adherence	~99%	~96%
Serious Adverse Events	5.3%	4.6%

Addressing Pill Fatigue and Treatment Stigma

While modern medicine has made HIV a manageable long-term condition, the psychological weight of daily dosing persists. A weekly option could reduce pill fatigue and the social stigma associated with daily medication, particularly for those already managing other health conditions with multiple tablets.

Chloe Orkin, Professor of Infection and Inequities and Dean for Health Care Transformation at Queen Mary University of London, stated that the first ever weekly oral therapy for HIV treatment could provide welcome relief from the lifelong burden of daily pill-taking for people living with HIV, noting that this is particularly important for those facing stigma or managing other HIV-associated health conditions with multiple medications.

The trial, funded by Gilead Sciences and Merck Sharp & Dohme, included a diverse participant group with a median age of 49. Approximately 31% of participants were Black, 26% Hispanic, and 11% Asian, while 21% were female.

Critical Limitations and Safety Gaps

Despite the promising data, the study has significant boundaries. The participants had already achieved at least six months of viral suppression and demonstrated high medication adherence, meaning the results might not apply to people who struggle with consistent daily dosing—the very group most likely to benefit from a weekly pill.

There is also a distinct difference in how the drugs handle co-infections. The weekly pill does not suppress hepatitis B, whereas two of the drugs in the daily Biktarvy regimen are active against both HIV and hepatitis B. Because of this, people with active hepatitis B were excluded from the trial; one unvaccinated participant in the weekly group developed hepatitis B during the study.

Safety data remains a point of scrutiny. While adverse events were reported in 79.3% of the weekly group and 78.5% of the daily group—mostly mild to moderate—experts emphasize the need for longer-term monitoring.

Michael Saag, MD, Director of the Center for AIDS Research at the University of Alabama at Birmingham, mentioned that while longer-term safety issues may emerge with any new regimen, both islatravir and lenacapavir have significant long-term safety data from various clinical trials and practical clinical experience.

The Mechanism of Action and Future Monitoring

The weekly tablet functions by combining islatravir and lenacapavir, which use complementary mechanisms to stop the virus from replicating. Other research, such as that from the American Society for Microbiology, has explored different approaches, such as the drug VH-499, which aims to destroy the HIV-1 virus by breaking down its capsid protein and activating B and T lymphocytes to create a protective shield.

The ISLEND-1 study is not yet finished. Participants will continue to be monitored for a total of 96 weeks to further assess the long-term safety and effectiveness of the islatravir-lenacapavir combination.