Gilead and Merck’s Once-Weekly HIV Pill Meets Phase 3 Goals

On 10 June 2026 Gilead Sciences and Merck reported that the once-weekly tablet of islatravir (2 mg) and lenacapavir (300 mg) met its primary efficacy endpoint in the Phase 3 ISLEND-1 and ISLEND-2 studies. The regimen was statistically non-inferior to daily standards—Biktarvy in ISLEND-1 and standard-of-care regimens in ISLEND-2—at week 48.

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The 2021 partnership pairs Merck’s nucleoside analog islatravir with Gilead’s capsid inhibitor lenacapavir, which was approved in 2022 for drug-resistant HIV (Sunlenca) and in 2023 for PrEP (Yeztugo). Islatravir received FDA approval two months earlier in the Idvynso combination for virologically suppressed adults.

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ISLEND-1 was a double-blind, active-controlled trial switching participants from Biktarvy; ISLEND-2 was open-label, enrolling patients on various regimens. The primary endpoint—percentage with HIV-1 RNA >= 50 copies/mL at week 48 (FDA snapshot)—was achieved in both studies, confirming non-inferiority. Safety was comparable to daily comparators, with no new safety signals.

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Around 39 million people worldwide rely on daily pills; missed doses raise the risk of viral rebound and resistance. A weekly tablet could simplify adherence, potentially lowering resistance and improving quality of life. The regimen remains investigational and no cure exists.

Gilead and Merck’s once-weekly HIV pill passes two major trials

Gilead’s spokesperson said, “If approved by regulators, the new combination could become the first once-weekly pill for the treatment of HIV.” Both companies plan to file the Phase 3 data globally and present results at an upcoming scientific congress, noting a safety profile matching existing therapies.

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All sources agree the product is not yet approved and data beyond week 48 are unavailable; no criticism was reported.

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• “Long-acting oral therapies represent a new wave of transformational innovation in HIV drug development, with the potential to reshape the landscape of care.” — Jared Baeten, MD PhD, Senior Vice President, Clinical Development, Virology Therapeutic Area Head, Gilead Sciences

Gilead and Merck’s once-weekly HIV pill passes two major trials

• “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.” — Eliav Barr, MD, Chief Medical Officer of Merck Research Laboratories

Gilead and Merck’s once-weekly HIV pill passes two major trialsGilead, Merck Report Positive Phase III HIV Study Data, End NSCLC StudyBenzingaGilead and Merck halt lung cancer trial but rep...Bloomberg

• “If approved by regulators, the new combination could become the first once-weekly pill for the treatment of HIV.” — Gilead spokesperson (email)

Bloomberg

Gilead and Merck will submit the ISLEND data to regulators in the U.S., Europe and other markets in the coming months and present full results at a future medical conference. Approval would add a weekly oral option to Gilead’s HIV portfolio, which already includes Biktarvy and Yeztugo, while Merck continues its once-monthly HIV prevention program.

Gilead and Merck’s once-weekly HIV pill passes two major trials