Bictegravir

Doravirine/islatravir would be the first FDA-approved two-drug regimen without an integrase inhibitor that demonstrated non-inferior efficacy and a generally comparable safety profile to the three-drug InSTI-based regimen, BIC/FTC/TAF, in a Phase 3 pivotal trial RAHWAY, NJ, USA I July 10, 2025 I Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced that the U.S. Food and Drug Administration (FDA) has accepted for review the New Drug Application (NDA) for doravirine/islatravir (DOR/ISL), an investigational, once-daily, oral, two-drug regimen for adults with HIV-1 infection that is virologically suppressed on antiretroviral therapy. The FDA has set a target action date of April 28, 2026, for the application under the Prescription Drug User Fee Act (PDUFA). “Merck has been at the forefront of HIV research for more than 35 years and we are pleased to continue our work to innovate and deliver new options that aim to meet the needs of the HIV community,” said Dr. Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories. “The health needs of people living with HIV often change over time – whether it’s managing comorbidities or navigating complex medication regimens. We believe DOR/ISL, if approved, will represent an important new complete regimen option designed to help meet their diverse needs.” The NDA is based on findings at Week 48 of two pivotal Phase 3 clinical trials ( MK-8591A-051 and MK-8591A-052 ) where DOR/ISL was demonstrated to be non-inferior to baseline antiretroviral therapy (bART) in the open-label trial MK-8591A-051 and non-inferior to bictegravir/emtrictabine/tenofovir alafenamide i [BIC/FTC/TAF (50mg/200mg/25mg)] in the double-blind trial MK-8591A-052. Across both trials, the safety profile of DOR/ISL was generally comparable to comparator baseline antiretroviral regimens in trial MK-8591A-051 and BIC/FTC/TAF in trial MK-8591A-052. Data from these trials were presented during the 2025 Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco. About the Phase 3 Trial MK-8591A-051 MK-8591A-051 is a Phase 3, open-label, randomized, active-controlled clinical trial evaluating the efficacy and safety of a switch to investigational, oral, once-daily DOR/ISL (100mg/0.25mg) in adults with HIV-1 infection that has been virologically suppressed using ART. The primary efficacy endpoint was the percentage of participants with HIV-1 RNA ≥50 copies/mL at Week 48 (non-inferiority margin 4%). In this trial, 551 adults with HIV-1 RNA <50 copies/mL for three months or more on oral 2- or 3-drug ART, with no history of treatment failure and no known virologic resistance to DOR, were randomized 2:1 and switched to DOR/ISL (n=366) or continued bART (n=185), stratified by bART regimen. The median age of participants was 51 years; 39.7% were assigned female sex at birth, 45.4% were Black or African American, and 14.5% were Hispanic or Latine. At baseline, 64.2% were treated with an InSTI-based regimen, 30.3% with an NNRTI-based regimen, and 5.4% with a protease inhibitor (PI)-based regimen, with median duration on current ART of 3.8 years (IQR 2.0-6.3). About the Phase 3 Trial MK-8591A-052 MK-8591A-052 is a Phase 3, double-blind, randomized, active-controlled clinical trial to evaluate the efficacy and safety of a switch to investigational, oral, once-daily DOR/ISL (100mg/0.25mg) in adults with HIV-1 infection that has been virologically suppressed on BIC/FTC/TAF (50mg/200mg/25mg). The primary efficacy endpoint was the percentage of participants with HIV-1 RNA ≥50 copies/mL at Week 48 (non-inferiority margin 4%). In this trial, 513 adults with HIV-1 who had virologic suppression for three months or more on BIC/FTC/TAF, no history of treatment failure and no known resistance to DOR were randomized (2:1) and switched to DOR/ISL (n=342) or continued treatment with BIC/FTC/TAF (n=171). The median age of participants was 47 years; 21.4% were assigned female sex at birth, 30.8% were Black or African American, and 22.8% were Hispanic or Latine. The median duration of BIC/FTC/TAF treatment prior to trial enrollment was 3.4 years (IQR 2.0-5.0). About Islatravir (MK-8591) and Merck’s HIV Research Islatravir (MK-8591), Merck’s investigational nucleoside reverse transcriptase translocation inhibitor (NRTTI), 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, resulting in delayed chain termination. Islatravir is under evaluation in multiple ongoing early and late-stage clinical trials in combination with other antiretrovirals for potential daily and once-weekly treatments for HIV-1, with islatravir serving as the anchor medicine in the treatment regimens based on its potency and resistance profile. In addition to the MK-8591A-051 and MK-8591A-052 trials, ongoing Phase 3 trials of daily DOR/ISL (100mg /0.25mg) include MK-8591A-053 in people with HIV who had not previously received treatment (treatment-naïve), and MK-8591A-054 evaluating open-label DOR/ISL (100 mg/0.25 mg) in individuals who participated in earlier Phase 3 trials of DOR/ISL (100 mg/0.75 mg). Islatravir in combination with Gilead’s lenacapavir is in Phase 3 development as a novel oral once-weekly treatment for HIV-1, and islatravir in combination with our company’s investigational non-nucleoside reverse transcriptase inhibitor (NNRTI) ulonivirine (MK-8507) is in Phase 2 development as an oral once-weekly treatment. Merck’s commitment to researching NRTTIs includes MK-8527, an investigational, novel oral, once-monthly NRTTI candidate that is in Phase 2 development for HIV-1 pre-exposure prophylaxis (PrEP). For an overview of Merck’s HIV treatment and prevention clinical development program, please click here . Merck’s Commitment to HIV For more than 35 years, Merck has been committed to scientific 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 designed to help people manage their HIV and to help prevent HIV, with the goal of reducing the growing burden of infection worldwide. We want to ensure people are not defined by HIV, and our work focuses on transformational innovations, collaborations with others in the global HIV community, and access initiatives aimed at helping to end the HIV epidemic for everyone. Indications and usage for PIFELTRO ® (doravirine) and DELSTRIGO ® (doravirine, lamivudine, and tenofovir disoproxil fumarate) in the U.S. PIFELTRO is indicated in combination with other antiretroviral (ARV) agents for the treatment of HIV-1 infection in adult patients with no prior ARV treatment history or to replace the current ARV regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable ARV regimen with no history of treatment failure and no known substitutions associated with resistance to doravirine. DELSTRIGO is indicated as a complete regimen for the treatment of HIV-1 infection in adult patients with no prior ARV treatment history or to replace the current ARV regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable ARV regimen with no history of treatment failure and no known substitutions associated with resistance to the individual components of DELSTRIGO. 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. For more information, visit www.merck.com and connect with us on X (formerly Twitter) , Facebook , Instagram , YouTube and LinkedIn . SOURCE: Merck

Gilead said it is “committed to working with regulatory authorities to resolve the issues underlying the clinical hold”. Credit: Melnikov Dmitriy via Shutterstock. The US Food and Drug Administration (FDA) has placed a clinical hold on several of Gilead’s trials evaluating two HIV treatment candidates, though the rest of the drugmaker’s diverse pipeline remains unaffected. Gilead said that impacted trials involved those evaluating GS-1720, an investigational integrase strand transfer inhibitor, and/or GS-4182, an investigational capsid inhibitor. The two main studies that have been stalled are WONDERS-1 and WONDERS-2, both Phase II/III trials evaluating a combination therapy with the two drugs. Shares in Nasdaq-listed Gilead opened 0.3% lower today (11 June) at $109.75, after initially dropping 4% yesterday following the announcement. The company’s market cap is $137bn. Gilead is considered the leading big pharma in HIV treatments. WONDERS-1 (NCT06544733) is trialling an oral weekly regimen of GS-1720 in combination with GS-4182 in virologically suppressed people with HIV-1, with efficacy and safety compared to Gilead’s already-approved pill Biktarvy (bictegravir). Meanwhile, WONDERS-2 (NCT06613685) is testing the same combo therapy with comparison to Biktarvy in HIV patients who had not received treatment. GlobalData Strategic Intelligence US Tariffs are shifting - will you react or anticipate? Don’t let policy changes catch you off guard. Stay proactive with real-time data and expert analysis. By GlobalData Learn more about Strategic Intelligence Three additional Phase I trials with either one or both drugs are also on hold, according to Gilead. The FDA placed a hold on the trials due to the identification of a safety signal of decreases in CD4+T-cell (CD4) and absolute lymphocyte counts in a subset of participants receiving the GS-1720 and GS-4182 combination. CD4+T-cells and lymphocytes are both crucial elements of the immune system. Low levels of either increase the likelihood of infections and other health problems. HIV itself can reduce CD4 count – a value lower than 200 indicates acquired immunodeficiency syndrome (AIDS). In a statement, Gilead said: “We intend to investigate and pursue the potential of both agents and are committed to working with regulatory authorities to resolve the issues underlying the clinical hold.” No timeline was provided by the company on when it expects the studies to resume. Gilead said the hold does not impact the rest of its HIV pipeline, which includes other long-acting oral and injectable investigational treatment combinations. Gilead’s HIV pipeline is split into segments of cures, preventions, and treatments. The WONDER studies are part of the treatment section, along with the ARISTRY programme evaluating an oral combination of bictegravir/lenacapavir, ISLEND studies with lenacapavir/islatravir, amongst others. Gilead already has several approved HIV treatments and prevention options in the US. Antiviral Biktarvy is the company’s top-selling HIV drug, generating global revenue of $13.4bn in 2024, an increase of 13% compared to 2023. Eyes of the pharmaceutical industry will be on Gilead’s upcoming Prescription Drug User Fee Act (PDUFA) date for lenacapavir on 19 June. According to GlobalData analysis, the drug, if approved, has the potential to revolutionise HIV pre-exposure prophylaxis (PrEP). Pharmaceutical Technology Excellence Awards - Have you nominated? Nominations are now open for the prestigious Pharmaceutical Technology Excellence Awards - one of the industry's most recognised programmes celebrating innovation, leadership, and impact . This is your chance to showcase your achievements, highlight industry advancements , and gain global recognition . Don't miss the opportunity to be honoured among the best - submit your nomination today! Nominate Now