Gilead's islatravir/lenacapavir matches Biktarvy at Week 48 in ISLEND-1
Gilead will detail full Week 48 data for its once-weekly oral HIV regimen at AIDS 2026 after topline results showed noninferiority to Biktarvy, setting up regulatory filings.
Executive Summary
- Gilead's Phase 3 once-weekly oral HIV regimen combining islatravir and lenacapavir matched the daily standard of care on the primary virologic suppression endpoint, and the company will present the full dataset at a major HIV conference.
- A once-weekly oral option, if it holds up on full disclosure, would compete directly with the daily single-tablet regimens that dominate treatment of virologically suppressed HIV, and the sponsors say the data are intended to support regulatory filings.
- The reverse transcriptase and capsid inhibitor space is active with dozens of trials, but most named comparators in earlier-phase development are also small-molecule oral regimens from Gilead and Merck sharing the same overall therapeutic logic rather than a differentiated mechanism.
- The presentation itself changes little beyond confirming detail; the more consequential step is what an FDA submission built on this dataset ultimately proposes for label scope and dosing.
The result
At Week 48, 0% of participants on islatravir/lenacapavir had HIV-1 RNA of 50 copies per milliliter or more under the FDA-defined Snapshot algorithm, versus 0.3% on Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide), meeting the registered primary endpoint of noninferiority. Gilead and Merck jointly stated the safety profile was consistent with prior findings and that no new safety signals were identified. The trial enrolled 609 virologically suppressed adults across 12 countries, including the United States, Japan, and Germany, and ran under double-blind randomization with three arms. NCT06630286+1Study to Compare an Oral Weekly Islatravir/Lenacapavir Regimen With Bictegravir/Emtricitabine/Tenofovir Alafenamide in Virologically Suppressed People With HIV-1NCT06630286Gilead to Present New HIV Research at AIDS 2026 Across Prevention, Treatment and CureJul 21, 2026
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
The conference presentation
Gilead confirmed it will present new HIV research, including full ISLEND-1 and companion ISLEND-2 results, in late-breaking oral sessions at the 26th International AIDS Conference from July 26 to July 31, 2026. Jared Baeten, Gilead's Senior Vice President of Clinical Development for the Virology Therapeutic Area, said the data reflect "our ongoing commitment to advancing HIV prevention, treatment and cure research, with the goal of expanding" choices for people affected by HIV. The topline endpoint has already been disclosed; the conference session will add the full dataset behind that number, including secondary measures such as CD4 T-cell count change and discontinuation rates due to treatment-emergent adverse events. Gilead+1Gilead to Present New HIV Research at AIDS 2026 Across Prevention, Treatment and CureJul 21, 2026Study to Compare an Oral Weekly Islatravir/Lenacapavir Regimen With Bictegravir/Emtricitabine/Tenofovir Alafenamide in Virologically Suppressed People With HIV-1NCT06630286
Regulatory path
Gilead and Merck said the Week 48 data from ISLEND-1 and its companion trial ISLEND-2 (NCT06630299) are intended to form the basis of regulatory submissions, though no authority or filing date has been specified. The trial's primary completion date moved twice, from June 2026 to April 2026 and then to April 17, 2026, a shift that closed the study ahead of, not behind, its original schedule. Enrollment held flat at 609 participants against the same 609-participant target, a routine registrational Phase 3 execution pattern. NCT06630286Study to Compare an Oral Weekly Islatravir/Lenacapavir Regimen With Bictegravir/Emtricitabine/Tenofovir Alafenamide in Virologically Suppressed People With HIV-1NCT06630286
The competitive field
The nearest mechanism comparator is Merck's own islatravir, being tested in a separate Phase 2/3 trial (NCT07266831) that shares the reverse transcriptase target but pairs the drug with a different partner compound. Within the broader reverse transcriptase and capsid inhibitor class, 31 active trials are studying this target in HIV-1 infection, and Phase 3 programs in this target-indication pairing have historically completed at a 7% failure rate across 111 completed and 8 terminated trials, a track record that favors late-stage execution in this class. Gilead's own lenacapavir, already used in a twice-yearly injectable prevention regimen, is the capsid-inhibitor half of the combination and is separately being tested in earlier-phase oral formats such as GS-3242.
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.