Gilead Sciences and Merck's Once-Weekly HIV Pill Maintains Viral Suppression in Phase 3 Trials

Jul 21, 2026

Gilead Sciences and Merck announced detailed Phase 3 results showing that their experimental once-weekly oral HIV tablet, combining islatravir and lenacapavir, maintained viral suppression at Week 48 and was non-inferior to daily comparator regimens in the ISLEND-1 and ISLEND-2 trials. Participants who switched to the weekly regimen in ISLEND-2 reported higher treatment satisfaction and a lower treatment burden. Separately, Gilead reported long-term extension data for twice-yearly lenacapavir for HIV prevention and said its no-profit supply program is planned to reach up to 3 million people through 2028.

Lenacapavir PrEP long-term efficacy

▪Adherence to twice-yearly lenacapavir injections in the open-label extension phases remained high, with 96% of participants in PURPOSE 1 and 92% in PURPOSE 2 continuing the regimen through 52 weeks.
▪In the Phase 3 PURPOSE 1 trial open-label extension, no new HIV infections were observed among participants receiving twice-yearly lenacapavir, including those who switched from once-daily oral pre-exposure prophylaxis.

Once-weekly islatravir/lenacapavir treatment

▪In the open-label ISLEND-2 trial, 0.3% of participants taking once-weekly islatravir/lenacapavir had HIV-1 RNA levels at or above 50 copies/mL at Week 48, compared to 1.3% of those who remained on daily standard-of-care regimens.
▪In the double-blind ISLEND-1 trial, no participants who switched to once-weekly islatravir/lenacapavir had HIV-1 RNA levels at or above 50 copies/mL at Week 48, compared to 0.3% of those who remained on once-daily Biktarvy.
▪Gilead Sciences and Merck announced that their once-weekly oral single-tablet regimen of islatravir 2 mg and lenacapavir 300 mg maintained virologic suppression at Week 48 in the Phase 3 ISLEND-1 and ISLEND-2 trials.

Lenacapavir global access expansion

▪Gilead Sciences is engaged in discussions with the Pan American Health Organization to explore pathways to expand access to twice-yearly lenacapavir in Latin America while advancing regional regulatory filings.
▪Gilead Sciences expanded its partnership commitments with PEPFAR and the Global Fund to increase the planned reach of its no-profit lenacapavir supply program by 50%, from 2 million to up to 3 million people through 2028.

Biktarvy pediatric outcomes

▪Gilead Sciences will present two-year real-world effectiveness and patient-reported outcomes from the BICSTaR study evaluating once-daily Biktarvy in people living with HIV who had detectable viremia.
▪Gilead Sciences will present five-year pediatric results from a study evaluating Biktarvy in pediatric populations at the 26th International AIDS Conference.

HIV cure research updates

▪Gilead Sciences will host community-based programming and symposia at the 26th International AIDS Conference, including a session titled 'Women Know What Works' focusing on HIV prevention, treatment, and care for women and girls.
▪Gilead Sciences will present scientific updates from its HIV cure research program at the 26th International AIDS Conference to advance research across the HIV continuum.

Twice-yearly injectable treatment pipeline

▪Gilead Sciences will present Week 104 outcomes from a Phase 2 study evaluating the twice-yearly investigational combination of lenacapavir with broadly neutralizing antibodies teropavimab and zinlirvimab.
▪Gilead Sciences is evaluating the twice-yearly injectable combination of lenacapavir, teropavimab, and zinlirvimab in two Phase 3 trials named Daybreak 1 and Daybreak 2.