HQ Team
June 10, 2026: Pharmaceutical giants Gilead Sciences and Merck announced that a once-weekly, single-tablet HIV treatment made up of islatravir and lenacapavir successfully met its goals of simplifying treatment for people living with the disease. The pill is as effective as current daily treatments.
If approved by regulators, this combination could become the world’s first once-weekly oral pill for HIV treatment, a major step forward for millions of people living with the virus around the globe.
Gilead Sciences and Merck said that the primary efficacy endpoint at Week 48 was met in both the Phase 3 ISLEND-1 and ISLEND-2 trials with the investigational oral treatment regimen of islatravir/lenacapavir.
The experimental medicine is part of a wave of longer-acting HIV drugs that public health experts hope will prove more convenient and accessible for patients than the daily pills long used to treat or prevent HIV.
The investigational regimen combines Merck’s islatravir, a next-generation nucleoside analog, with Gilead’s lenacapavir, a first-in-class capsid inhibitor that targets HIV at multiple stages of its lifecycle.
In simple terms, islatravir works by mimicking the building blocks of DNA to stop the virus from copying itself, while lenacapavir attacks the protein shell that protects HIV’s genetic material. Together, they form a powerful combination that can keep the virus suppressed with just one pill per week.
The combination tablet came out of an unusual collaboration the two companies struck in 2021
The trials
The ISLEND trials are evaluating the efficacy and safety of islatravir 2 mg/lenacapavir 300 mg in people with HIV who are virologically suppressed and switched from BIKTARVY (ISLEND-1) or standard of care antiretroviral regimens (ISLEND-2).
ISLEND-1 is a Gilead-sponsored, multicenter Phase 3 randomized, double-blind, active-controlled trial designed to evaluate the safety and efficacy of switching to a once-weekly tablet of islatravir/lenacapavir versus continuing treatment with BIKTARVY in people with virologically suppressed HIV.
In both studies, the regimen met the primary endpoint of maintaining viral suppression through Week 48. The combination was found to be statistically non-inferior to daily treatment regimens, including Biktarvy in ISLEND-1 and a range of standard-of-care antiretroviral therapies in ISLEND-2.
The safety profile of ISL/LEN was generally comparable to the comparator regimens studied in the ISLEND trials, and no new safety concerns were identified.
“Long-acting oral therapies represent a new wave of transformational innovation in HIV drug development, with the potential to reshape the landscape of care,” said Jared Baeten, MD, PhD, Senior Vice President, Clinical Development, Virology Therapeutic Area Head, Gilead Sciences.
“By advancing this investigational novel once-weekly oral regimen of islatravir and lenacapavir, we aim to bring forward a new long-acting oral option that, if approved, would represent the first of its kind with less frequent dosing and further expand options for people living with HIV,” said Eliav Barr, MD, Chief Medical Officer of Merck Research Laboratories
Regulatory submissions
Gilead and Merck plan to file the Phase 3 data from the ISLEND trials with regulatory authorities globally and submit the detailed findings for presentation at a future scientific congress.
Gilead is also working on other combinations with lenacapavir, alongside other next-generation antivirals, as part of its efforts to extend its multibillion-dollar HIV portfolio into the coming decades. Merck also started a Phase 3 trial last year on a once-monthly pill to prevent HIV.
Background on the individual drugs
Gilead’s lenacapavir has been on the market since 2022, when it was approved in the U.S. as Sunlenca for twice-yearly administration for those with drug-resistant HIV. Twelve months ago, the FDA signed off on lenacapavir for pre-exposure prophylaxis (PrEP), known commercially as Yeztugo.
Lenacapavir is the active ingredient in Yeztugo, the widely celebrated drug that prevents HIV with just two injections every year.
Less than two months ago, islatravir was approved for the first time by the FDA in combination with doravirine. The regimen, known commercially as Idvynso, was endorsed to replace current antiretroviral regimens among adults with HIV who are virologically suppressed and who have no history of virologic treatment failure.
Why this matters
For the roughly 39 million people living with HIV worldwide, treatment currently means taking pills every single day. Missing doses can allow the virus to replicate and become drug-resistant. A once-weekly pill could dramatically improve how easy it is for patients to stick to their treatment plans.
The experimental medicine is part of a wave of longer-acting HIV drugs that public health experts hope will prove more convenient and accessible for patients than the daily pills long used to treat or prevent HIV.
It is important to note, however, that islatravir and lenacapavir in combination are still investigational and not yet approved for use, and there is currently no cure for HIV or AIDS.
