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Presentations include data on daily and investigational once-weekly oral treatments and investigational once-monthly oral HIV pre-exposure prophylaxis
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New data include Phase 3 subgroup analyses and patient-reported outcomes of investigational once-weekly oral combination of islatravir/lenacapavir (ISL/LEN)
November 2, 2026--RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that new data across its HIV treatment and prevention pipeline and portfolio will be presented at HIV Drug Therapy Glasgow 2026 (HIV Glasgow 2026), taking place Nov 8–11, 2026, in Glasgow, Scotland. Presentations will highlight Merck’s strategy to expand oral options in both HIV treatment and prevention, including data on once-daily IDVYNSO® (doravirine/islatravir), the investigational once-weekly oral treatment regimens islatravir/lenacapavir (ISL/LEN) and islatravir/ulonivirine (ISL/ULO), and the investigational once-monthly oral pre-exposure prophylaxis (PrEP) alimatravir (AMI, MK-8527).
“The data being presented at HIV Glasgow reflect the breadth of our research across HIV treatment and prevention,” said Dr. Luisa Stamm, associate vice president and HIV section head at Merck Research Laboratories. “Our goal is to bring forward oral options, including daily and once-weekly HIV treatment regimens, as well as a once-monthly HIV prevention pill. Because no single medicine works for every person, we are committed to expanding choices that may help address the diverse needs and preferences of people living with HIV or those who could benefit from PrEP.”
At HIV Glasgow, Merck will present Phase 3 subgroup analyses of once-daily IDVYNSO, including Week 48 resistance and weight analyses from Trial 53 comparing IDVYNSO to bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) in adults with HIV-1 who had not previously received antiretroviral treatment, as well as Week 96 patient-reported outcomes for IDVYNSO in adults with virologically suppressed HIV-1. Separately, the U.S. Food and Drug Administration (FDA) has accepted two supplemental New Drug Applications for IDVYNSO (doravirine and islatravir): one based on the Phase 3 Trial 053 in adults who had not previously received antiretroviral treatment and one based on the Phase 3 Trials 051 and 052 to include 96-week data in virologically suppressed adults. The FDA has set a Prescription Drug User Fee Act (PDUFA) or target action date of April 22, 2027, for both applications.
IDVYNSO (doravirine/islatravir) is a two-drug single-tablet regimen of 100 mg doravirine and 0.25 mg islatravir and is approved in the United States for the treatment of HIV-1 infection in adults to replace the current antiretroviral regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine.
The investigational once-weekly oral regimen of islatravir and lenacapavir pairs Merck’s islatravir, a potent nucleoside analog with multiple mechanisms of action including HIV-1 reverse transcriptase translocation inhibition, with Gilead’s lenacapavir, a first-in-class capsid inhibitor that disrupts HIV-1 at multiple stages of its lifecycle. Data to be presented at HIV Glasgow from the Phase 3 ISLEND-1 and ISLEND-2 trials will include Week 48 safety and efficacy subgroup analyses across diverse demographic populations. ISLEND-2 data will also include Week 48 patient-reported outcomes and a qualitative substudy of participant and provider experiences with once-weekly dosing. These data further characterize Phase 3 safety and efficacy findings first presented at AIDS 2026, providing additional insight across patient subgroups, treatment experiences, and preferences with once-weekly oral therapy.
Key presentations at HIV Glasgow 2026 by program:
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Doravirine/islatravir (once-daily oral treatment)
DOR/ISL analyses: Week 48 resistance and weight analyses in adults with HIV-1 who had not previously received antiretroviral treatment and Week 96 patient-reported outcomes assessing treatment satisfaction in adults living with virologically suppressed HIV-1 (Abstract #P060, Abstract #P401, Abstract #P063).
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Islatravir/lenacapavir (investigational once-weekly oral treatment)
ISLEND-1 (Phase 3): Week 48 subgroup analyses evaluating a switch to once-weekly ISL/LEN compared to continuing a daily regimen of BIC/FTC/TAF in adults living with virologically suppressed HIV-1 (Abstract #P050).
ISLEND-2 (Phase 3): Week 48 subgroup analyses evaluating a switch to once-weekly ISL/LEN compared to continuing daily standard-of-care treatment in adults living with virologically suppressed HIV-1, accompanied by Week 48 patient-reported outcomes and a qualitative substudy detailing participant and provider experiences (Abstract #P049, Abstract #P057, Abstract #P056).
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Islatravir + ulonivirine (investigational once-weekly oral treatment)
Week 24 data from the Phase 2b MK-8591B-060 ( NCT06891066) study that informed an updated population pharmacokinetic model of ulonivirine. The model characterizes exposure and activity over time to support dosing recommendations for the investigational once-weekly combination of ulonivirine 200 mg and islatravir 2 mg in adults living with virologically suppressed HIV-1 (Abstract #P038).
Phase 1 clinical pharmacology data on the absorption, metabolism, and excretion profile of investigational ulonivirine (Abstract #P265).
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Alimatravir (AMI [MK-8527]; investigational once-monthly oral PrEP)
AMI is being evaluated as a potential once-monthly oral prevention option for HIV-1 in two ongoing Phase 3 trials. Adult enrollment in both trials is now complete. Participant demographics will be presented from the adult cohorts of EXPrESSIVE-10 and EXPrESSIVE-11 (Abstract #P017, Abstract #P015).
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Merck symposia during HIV Glasgow 2026
Policy symposium:Reimagining HIV elimination: Policy solutions for the next decade
Date and time: Monday, Nov. 9, 18:15–19:30 GMT/UTC+0, Scottish Event Campus (Clyde Auditorium)Medical symposium:Considerations for individualizing HIV care: Cardiometabolic health, unmet needs and the older adult
Date and time: Tuesday, Nov. 10, 12:45–13:45 GMT/UTC+0, Scottish Event Campus (Clyde Auditorium)
Both events will be open to registered attendees, in person and virtually.
Details on abstracts listed above and select additional abstracts:
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Abstract Title and Presenting Author |
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HIV Treatment |
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Resistance analysis at Week 48 of daily doravirine/islatravir (100 mg/0.25 mg) versus bictegravir/emtricitabine/tenofovir alafenamide in a blinded Phase 3 study in adults initiating treatment for HIV-1. T. Diamond. |
Abstract #P060 Poster Presentation
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Evaluation of weight in previously untreated adults living with HIV-1 initiated on doravirine/islatravir (100 mg/0.25 mg) vs bictegravir/emtricitabine/tenofovir alafenamide: Week 48 results from a randomised, double-blind Phase 3 study. J. Rockstroh. |
Abstract #P401 Poster Presentation |
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Patient-reported outcomes with doravirine/islatravir (100/0.25 mg) once daily versus bictegravir/emtricitabine/tenofovir alafenamide in virologically suppressed adults living with HIV-1: Phase 3 results through Week 96. G. Sinclair. |
Abstract #P063 Poster Presentation
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Once-weekly ulonivirine provides a week of forgiveness after a missed dose. M. Pham. |
Abstract #P038 Poster Presentation |
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Phase 1 study to investigate the absorption, metabolism, and excretion of ulonivirine, a non-nucleoside reverse transcriptase inhibitor, in adults without HIV. G. Gillespie. |
Abstract #P265 Poster Presentation |
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Once-weekly oral islatravir/lenacapavir (ISL/LEN) versus daily bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) in virologically suppressed adults with HIV-1: Week 48 subgroup analyses of the Phase 3 ISLEND-1 trial. J. Rockstroh.* |
Abstract #P050 Poster Presentation |
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Efficacy and safety of once-weekly oral islatravir/lenacapavir (ISL/LEN) versus daily standard of care (SOC) across demographic and clinical subgroups through Week 48 in the Phase 3 ISLEND-2 trial. M. Parczewski.* |
Abstract #P049 Poster Presentation |
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Quality of life and treatment preference with weekly ISL/LEN versus standard of care: Week 48 patient-reported outcome analysis of the Phase 3 ISLEND-2 Study. M. Ramgopal.* |
Abstract #P057 Poster Presentation |
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Understanding treatment experiences with weekly oral islatravir/lenacapavir in the Phase 3 ISLEND-2 study: Participant and provider interviews. C. Orkin.* |
Abstract #P056 Poster Presentation |
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HIV Prevention |
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EXPrESSIVE-10: A Phase 3 study evaluating MK-8527 oral once monthly for HIV pre-exposure prophylaxis in cisgender women who are at greater likelihood of HIV exposure. R. Heffron. |
Abstract #P017 Poster Presentation
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EXPrESSIVE-11: A Phase 3 study evaluating MK-8527 oral once monthly for HIV pre-exposure prophylaxis in cisgender men who have sex with men, transgender women, transgender men, and gender nonbinary individuals who are at greater likelihood of HIV exposure. R. Landovitz; presenting author: R. Plank. |
Abstract #P015 Poster Presentation
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Phase 1 study to evaluate the effect of a single supratherapeutic dose of MK-8527 on QTc interval prolongation in healthy adults. R. Carstens. |
Abstract #P268 Poster Presentation |
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*In collaboration with Gilead. |
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About Merck’s HIV research
Islatravir (MK-8591) is Merck’s potent nucleoside analog that blocks HIV-1 replication by multiple mechanisms including inhibition of reverse transcriptase translocation, resulting in immediate chain termination, and induction of structural changes in the viral DNA (delayed chain termination). It is being studied in multiple ongoing early and late-stage clinical trials of two-drug regimens in combination with other antiretrovirals for potential treatments for HIV-1. Islatravir is approved in combination with doravirine as IDVYNSO® (doravirine/islatravir) in the United States and Japan as a once-daily, single-tablet regimen for adults with virologically suppressed HIV-1. It continues to be evaluated in Phase 3 trials in combination with Merck’s doravirine as a once-daily regimen for adults who had not previously received antiretroviral treatment; in combination with Gilead’s lenacapavir as a novel once-weekly oral treatment for HIV-1 in virologically suppressed adults (ISLEND-1 [NCT06630286] and ISLEND-2 [NCT06630299]); and in combination with Merck’s investigational NNRTI ulonivirine (MK-8507) in Phase 2b development (MK-8591B-060 [NCT06891066] and MK-8591B-062 [NCT07266831]) as a once-weekly oral regimen.
Alimatravir (MK-8527), an investigational once-monthly oral PrEP, is being evaluated in two Phase 3 clinical trials. With financial support from the Gates Foundation, the Phase 3 EXPrESSIVE-10 trial (MK-8527-010, NCT07071623) is evaluating the safety and efficacy of alimatravir in adolescent girls and young women in Kenya, South Africa and Uganda. EXPrESSIVE-11 (MK-8527-011, NCT07044297) is evaluating the safety and efficacy of alimatravir among people with greater likelihood of HIV-1 exposure in 16 countries. Adult enrollment in both trials is now complete.
Merck’s commitment to HIV
For more than 40 years, Merck has been committed to research and discovery in HIV, leading to scientific breakthroughs that have helped change HIV treatment. Our work has helped pioneer the development of new options across multiple drug classes to help those impacted by HIV. Today, we are developing a series of antiviral options for both HIV treatment and prevention. We’re inspired by the lived experiences of the HIV community as we advance research with real life in mind. Our work focuses on potentially transformative innovations, collaborations with others in the global HIV community, and access initiatives to help end the HIV epidemic.
About Merck
At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities.