Tenofovir Alafenamide Fumarate

February 25, 2026 12:37 pm EST DOR/ISL is the first non-INSTI, two-drug regimen to demonstrate non-inferiority and a similar safety profile at Week 48 to BIC/FTC/TAF in adults living with HIV-1 who had not previously received antiretroviral treatment DOR/ISL maintained virologic suppression at Week 96 in adults with virologically suppressed HIV-1 who switched from other oral antiretroviral therapies, including BIC/FTC/TAF RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced the presentation of results from three pivotal Phase 3 trials evaluating the investigational, once-daily, oral, two-drug regimen of doravirine/islatravir [DOR/ISL (100 mg/0.25 mg), (MK-8591A)] in adults with HIV-1. The findings were shared in late-breaking presentations at the 33rd Conference on Retroviruses and Opportunistic Infections (CROI) being held in Denver. “We are proud to continue building on our 40-year history of HIV research with the presentation of compelling new data from our HIV pipeline at CROI this year,” said Dr. Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories. “Islatravir blocks HIV-1 replication through multiple mechanisms, including reverse transcriptase translocation inhibition, and could serve as the anchor for a series of two-drug, non-INSTI, daily and weekly treatment regimens. If approved, DOR/ISL will be the first of these regimens in our portfolio and may provide an important new option to help meet the evolving treatment needs of people living with HIV.” The Phase 3, double-blind, clinical trial MK-8591A-053 evaluating DOR/ISL versus bictegravir/emtricitabine/tenofovir alafenamidei [(50 mg/200 mg/25 mg),(BIC/FTC/TAF)] in adults living with HIV-1 who had not previously received antiretroviral treatment (treatment-naïve), met its primary efficacy endpoint of percentage of participants achieving viral suppression (HIV-1 RNA <50 copies/mL), demonstrating non-inferiority for DOR/ISL compared to BIC/FTC/TAF at Week 48, 91.8% and 90.6% respectively (treatment difference 1.2%, 95% CI: -3.7, 6.2, p<0.001). The safety profile was similar between both treatment groups and consistent with that observed in previous studies. Drug-related adverse events (AEs) and discontinuations due to drug-related AEs were similar between groups (14% for DOR/ISL and 18% for BIC/FTC/TAF; 1.1% for DOR/ISL and 2.2% for BIC/FTC/TAF, respectively). These data, which are being published simultaneously in The Lancet HIV, build on the previously reported Phase 3 data in adults with virologically suppressed HIV-1 and will form the basis of future regulatory applications. “These new Phase 3 results are meaningful, showing that an investigational two-drug regimen without an INSTI demonstrated non-inferior efficacy and a comparable safety profile versus BIC/FTC/TAF in previously untreated adults with HIV-1, including those with advanced disease,” said Dr. Jürgen K. Rockstroh, professor of medicine, head of the HIV Outpatient Clinic at the University of Bonn. “This study evaluated a diverse, global population, and included a significant proportion of participants with high viral loads and low CD4 counts. These findings add to the growing evidence supporting the potential role of DOR/ISL in HIV care.” New 96-week data from the Phase 3 MK-8591A-052 and MK-8591A-051 trials evaluating DOR/ISL vs. BIC/FTC/TAF or baseline antiretroviral therapy (bART), in participants with virologically suppressed HIV-1 and who were switched to DOR/ISL, were also presented. In both trials, DOR/ISL maintained high rates of viral suppression at Week 96 and had a similar safety profile to BIC/FTC/TAF and bART. The 48-week data from these trials supported the initial New Drug Application (NDA) for DOR/ISL for the treatment of HIV-1 infection in adults who are virologically-suppressed on a stable antiretroviral regimen; the U.S. FDA has set a target action date of April 28, 2026 for the application under the Prescription Drug User Fee Act (PDUFA). In the U.S., doravirine is approved for the treatment of adults with HIV-1 in combination with other antiretrovirals as a single agent (PIFELTRO) and a component of a single-tablet regimen [DELSTRIGO; doravirine, lamivudine, and tenofovir disoproxil fumarate (DOR/3TC/TDF)]. “As people living with HIV age, managing other health conditions becomes a reality for many, making it especially important to have treatment options that can help meet each person’s unique health needs,” said Dr. Amy Colson, director of research at Community Resource Initiative, Cambridge, Massachusetts. “Over time, people may need to adjust their HIV treatment regimens because of comorbidities, concerns about toxicities, tolerability challenges, or a desire for regimens with fewer medications. These 96-week data are encouraging, showing a non-INSTI option like investigational DOR/ISL could offer an important alternative.” About the Phase 3 data from MK-8591A-053 MK-8591A-053 is an ongoing Phase 3 randomized, active-controlled, double-blind, clinical trial evaluating the efficacy and safety of investigational, once-daily DOR/ISL (100 mg/0.25 mg) versus BIC/FTC/TAF in adults living with HIV-1 infection who had not previously received antiretroviral treatment. Participants were randomized 1:1 to DOR/ISL (n=269) or BIC/FTC/TAF (with matching placebos) (n=267), stratified by screening CD4+ T-cell count (<200 cells/mm³) and HIV-1 RNA (>100,000 copies/mL). The primary efficacy endpoint was the percentage of participants with HIV-1 RNA <50 copies/mL at Week 48 (non-inferiority margin 10%). Of the total participants enrolled in the trial, 36.8% had baseline HIV-1 RNA >100,000 copies/mL, 10.3% had HIV-1 RNA >500,000 copies/mL and 17.2% had baseline CD4+ T-cell count <200 cells/mm3. At Week 48, virological efficacy as measured by the percentage of participants with HIV-1 RNA levels < 50 copies/mL, was comparable in participants on DOR/ISL versus BIC/FTC/TAF with screening HIV-1 RNA >100,000 copies/mL (94.0% vs 87.6%, respectively) and >500,000 copies/mL (90.3% vs 84.4%, respectively). Drug-related AEs were reported in 14.1% of participants on DOR/ISL and 18.0% on BIC/FTC/TAF and discontinuations due to AEs (1.1% vs. 2.2%) were similar in both groups. Immune reconstitution was similar in DOR/ISL vs. comparator with no between-group differences in mean increases in CD4+ T-cell counts or total lymphocyte counts (TLC). About the Phase 3 data from MK-8591A-052 MK-8591A-052 is a Phase 3, randomized, active-controlled, double-blind, clinical trial to evaluate the efficacy and safety of a switch to investigational, once-daily DOR/ISL (100 mg/0.25 mg) in adults with HIV-1 infection that has been virologically suppressed on BIC/FTC/TAF (50 mg/200 mg/25 mg). 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 primary efficacy endpoint, the percentage of participants with HIV-1 RNA ≥50 copies/mL at Week 48 (non-inferiority margin 4%), was met, demonstrating non-inferiority to BIC/FTC/TAF; 1.5% of participants who switched to DOR/ISL had a viral load of ≥50 copies/mL at Week 48, compared to 0.6% on BIC/FTC/TAF (treatment difference 0.9%, 95% CI -1.9, 2.9). Results at Week 48 were recently published in The Lancet. At Week 96, DOR/ISL continued to demonstrate similar efficacy compared to BIC/FTC/TAF; 1.5% of participants on DOR/ISL had a viral load of ≥50 copies/mL compared to 1.2% of participants on BIC/FTC/TAF (treatment difference 0.3%, 95% CI -2.8, 2.4); 88.9% of participants on DOR/ISL maintained virologic suppression (HIV-1 RNA <50 copies/mL) compared to 90.1% of participants continuing BIC/FTC/TAF (treatment difference -1.2%, 95% CI -6.5, 5.0). No hypothesis testing was performed for these secondary endpoints. The safety profile for DOR/ISL at Week 96 continued to be similar to BIC/FTC/TAF with no new safety findings. No additional drug-related serious adverse events were reported in any group between Week 48 and Week 96. At Week 96, rates of discontinuation due to AEs were similar for both groups (3.2% vs. 2.9%). There were no differences between trial arms in CD4+ T-cell count or TLC changes through Week 96. About the Phase 3 data from MK-8591A-051 MK-8591A-051 is a Phase 3, open-label randomized, active-controlled, clinical trial to evaluate the efficacy and safety of a switch to investigational, once-daily DOR/ISL (100 mg/0.25 mg) in adults with HIV-1 infection that has been virologically suppressed using bART. 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 primary efficacy endpoint, percentage of participants with HIV-1 RNA ≥50 copies/mL at Week 48 (non-inferiority margin 4%), was met, demonstrating DOR/ISL to be non-inferior to bART; 1.4% of participants who received DOR/ISL had a viral load of ≥50 copies/mL at Week 48, compared to 4.9% on bART (treatment difference -3.6%, 95% CI -7.8, -0.8). After Week 48 of the comparative portion of the study, all participants received open-label DOR/ISL through Week 144. Results at Week 48 were recently published in The Lancet. At Week 96, 1.9% of participants who continued on DOR/ISL for 96 weeks had HIV-1 RNA ≥50 copies/mL and 1.1% of participants who switched from bART to DOR/ISL at Week 48. Additionally, 92.6% of participants who were on DOR/ISL through 96 weeks and 96.6% of participants who switched to DOR/ISL at Week 48 maintained virologic suppression (HIV-1 RNA <50 copies/mL) at Week 96. At Week 96, there were similar rates of drug-related AEs between those who continued on DOR/ISL (13.7%) for 96 weeks and for those who switched from bART to DOR/ISL at Week 48 (11.3%) and rates of discontinuations due to AEs for those on DOR/ISL for 96 weeks (1.1%) and for those who switched from bART to DOR/ISL at Week 48 (0.6%) were similar. The mean percent change in total lymphocyte and CD4 counts were similar for participants who continued on DOR/ISL and switched from bART to DOR/ISL. No participants discontinued treatment due to decreased CD4+ T-cell count or TLC. About Islatravir (MK-8591) and Merck’s HIV Research Islatravir (MK-8591) is Merck’s investigational 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. 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 these two-drug regimens. Islatravir in combination with Gilead’s lenacapavir is in Phase 3 development as a novel oral once-weekly treatment for HIV-1 [ISLEND-1 (NCT06630286) and ISLEND-2 (NCT06630299)], and islatravir in combination with our company’s investigational non-nucleoside reverse transcriptase inhibitor (NNRTI) ulonivirine (MK-8507) is in Phase 2b development (MK-8591B-060, NCT06891066 and MK-8591B-062, NCT07266831) as an oral once-weekly treatment. MK-8527 is the company’s investigational, novel, once-monthly, oral candidate for pre-exposure prophylaxis (PrEP) for HIV-1. The Phase 3 EXPrESSIVE-11 (MK-8527-011, NCT07044297) trial is evaluating the safety and efficacy of MK-8527 as PrEP to reduce the risk of sexually acquired HIV-1 infection among people likely to be exposed to HIV-1 in 16 countries. The Phase 3 EXPrESSIVE-10 (MK-8527-010, NCT07071623) trial is evaluating the safety and efficacy of MK-8527 as PrEP to reduce the risk of sexually acquired HIV-1 infection among women and adolescent girls in sub-Saharan Africa. Both trials are now enrolling. For an overview of Merck’s HIV treatment and prevention clinical development program, please click here. 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. Selected Safety Information Warning: Posttreatment Acute Exacerbation of Hepatitis B Virus (HBV) for DELSTRIGO All patients with HIV-1 should be tested for the presence of HBV before initiating ARV therapy. Severe acute exacerbations of HBV have been reported in people with concomitant HIV-1 and HBV who have discontinued products containing lamivudine or tenofovir disoproxil fumarate (TDF), which are components of DELSTRIGO. Patients coinfected with HIV-1 and HBV who discontinue DELSTRIGO should be monitored with both clinical and laboratory follow-up for at least several months after stopping DELSTRIGO. If appropriate, initiation of anti-HBV therapy may be warranted. Contraindications PIFELTRO and DELSTRIGO are contraindicated when coadministered with drugs that are strong cytochrome P450 (CYP)3A enzyme inducers (including the anticonvulsants carbamazepine, oxcarbazepine, phenobarbital, and phenytoin; the androgen receptor inhibitor enzalutamide; the antimycobacterials rifampin and rifapentine; the cytotoxic agent mitotane; and the herbal product St. John’s wort (Hypericum perforatum)), as significant decreases in doravirine plasma concentrations may occur, which may decrease the effectiveness of DELSTRIGO and PIFELTRO. DELSTRIGO is contraindicated in patients with a previous hypersensitivity reaction to lamivudine. Warnings and Precautions Severe Skin Reactions Severe skin reactions, including Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), have been reported during the postmarketing experience with doravirine-containing regimens. Discontinue PIFELTRO or DELSTRIGO, and other medications known to be associated with severe skin reactions, immediately if a painful rash with mucosal involvement or a progressive severe rash develops. Clinical status should be closely monitored, and appropriate therapy should be initiated. New or Worsening Renal Impairment Renal impairment, including cases of acute renal failure and Fanconi syndrome, have been reported with the use of TDF. DELSTRIGO should be avoided with concurrent or recent use of a nephrotoxic agent (e.g., high-dose or multiple NSAIDs). Cases of acute renal failure after initiation of high-dose or multiple NSAIDs have been reported in people living with HIV with risk factors for renal dysfunction who appeared stable on TDF. Prior to or when initiating DELSTRIGO, and during treatment, assess serum creatinine, estimated creatinine clearance, urine glucose, and urine protein in all patients. In patients with chronic kidney disease, also assess serum phosphorus. Discontinue DELSTRIGO in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome. Discontinue DELSTRIGO if estimated creatinine clearance declines below 50 mL/min. Bone Loss and Mineralization Defects In clinical trials in adults living with HIV, TDF was associated with slightly greater decreases in bone mineral density (BMD) and increases in biochemical markers of bone metabolism. Serum parathyroid hormone levels and 1,25 Vitamin D levels were also higher. Cases of osteomalacia associated with proximal renal tubulopathy have been reported with the use of TDF. The effects of TDF-associated changes in BMD and biochemical markers on long-term bone health and future fracture risk in adults are unknown. Immune Reconstitution Syndrome Immune reconstitution syndrome can occur, including the occurrence of autoimmune disorders with variable time to onset, which may necessitate further evaluation and treatment. Drug Interactions Because DELSTRIGO is a complete regimen, coadministration with other antiretroviral medications for the treatment of HIV-1 infection is not recommended. Coadministration of PIFELTRO with efavirenz, etravirine, or nevirapine is not recommended. If DELSTRIGO is coadministered with rifabutin, take one tablet of DELSTRIGO once daily, followed by one tablet of doravirine (PIFELTRO) approximately 12 hours after the dose of DELSTRIGO. If PIFELTRO is coadministered with rifabutin, increase PIFELTRO dosage to one tablet twice daily (approximately 12 hours apart). Consult the full Prescribing Information prior to and during treatment for more information on potential drug-drug interactions. Dosage and Administration/Specific Populations Renal Impairment Because DELSTRIGO is a fixed-dose combination tablet and the dosage of lamivudine and TDF cannot be adjusted, DELSTRIGO is not recommended in patients with estimated creatinine clearance less than 50 mL/min. Adverse Reactions The most common adverse reactions with DELSTRIGO (incidence ≥5%, all intensities) were dizziness (7%), nausea (5%), and abnormal dreams (5%). The most common adverse reactions with PIFELTRO (incidence ≥5%, all intensities) were nausea (7%), dizziness (7%), headache (6%), fatigue (6%), diarrhea (6%), abdominal pain (5%), and abnormal dreams (5%). By week 96 in DRIVE-FORWARD, 2% of adult participants in the PIFELTRO group and 3% in the darunavir+ritonavir (DRV+r) group had adverse events leading to discontinuation of study medication. By week 96 in DRIVE-AHEAD, 3% of adult participants in the DELSTRIGO group and 7% in the efavirenz (EFV)/emtricitabine (FTC)/TDF group had adverse events leading to discontinuation of study medication. In DRIVE-FORWARD, mean changes from baseline at week 48 in LDL-cholesterol (LDL-C) and non-HDL-cholesterol (non-HDL-C) were pre-specified. LDL-C: -4.6 mg/dL in the PIFELTRO group vs 9.5 mg/dL in the DRV+r group. Non-HDL-C: -5.4 mg/dL in the PIFELTRO group vs 13.7 mg/dL in the DRV+r group. The clinical benefits of these findings have not been demonstrated. In DRIVE-AHEAD, mean changes from baseline at week 48 in LDL-C and non-HDL-C were pre-specified. LDL-C: -2.1 mg/dL in the DELSTRIGO group vs 8.3 mg/dL in the EFV/FTC/TDF group. Non-HDL-C: -4.1 mg/dL in the DELSTRIGO group vs 12.7 mg/dL in the EFV/FTC/TDF group. The clinical benefits of these findings have not been demonstrated. In DRIVE-SHIFT, mean changes from baseline at week 24 in LDL-C and non-HDL-C were pre-specified. LDL-C: -16.3 mg/dL in the DELSTRIGO group vs -2.6 mg/dL in the PI + ritonavir group. Non-HDL-C: -24.8 mg/dL in the DELSTRIGO group vs -2.1 mg/dL in the PI + ritonavir group. The clinical benefits of these findings have not been demonstrated. In DRIVE-AHEAD, neuropsychiatric adverse events were reported in the three pre-specified categories of sleep disorders and disturbances, dizziness, and altered sensorium. Twelve percent of adult participants in the DELSTRIGO group and 26% in the EFV/FTC/TDF group reported neuropsychiatric adverse events of sleep disorders and disturbances; 9% in the DELSTRIGO group and 37% in the EFV/FTC/TDF group reported dizziness; and 4% in the DELSTRIGO group and 8% in the EFV/FTC/TDF group reported altered sensorium. The safety of DELSTRIGO in virologically suppressed adults was based on week 48 data from participants in the DRIVE-SHIFT trial. Overall, the safety profile in virologically suppressed adult participants was similar to that in participants with no ARV treatment history. Serum ALT and AST Elevations: In the DRIVE-SHIFT trial, 22% and 16% of participants in the immediate switch group experienced ALT and AST elevations greater than 1.25 X ULN, respectively, through 48 weeks on DELSTRIGO. For these ALT and AST elevations, no apparent patterns with regard to time to onset relative to switch were observed. One percent of participants had ALT or AST elevations greater than 5 X ULN through 48 weeks on DELSTRIGO. The ALT and AST elevations were generally asymptomatic, and not associated with bilirubin elevations. In comparison, 4% and 4% of participants in the delayed switch group experienced ALT and AST elevations of greater than 1.25 X ULN through 24 weeks on their baseline regimen. Pregnancy/Breastfeeding There is a pregnancy exposure registry that monitors pregnancy outcomes in individuals exposed to PIFELTRO or DELSTRIGO during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263. Inform individuals with HIV-1 infection of the potential risks of breastfeeding, including: (1) HIV-1 transmission (in HIV-1–negative infants), (2) developing viral resistance (in HIV-1–positive infants), and (3) serious adverse reactions in a breastfed infant similar to those seen in adults. Merck’s Commitment to HIV For 40 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 been pioneering in 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 HIV and protect people from HIV. We are researching for real life and want to ensure people are not defined by HIV. Our work focuses on transformational innovations, collaborations with others in the global HIV community, and access initiatives aimed at the goal of helping to end the HIV epidemic for everyone. 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. Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA This news release of Merck & Co., Inc., Rahway, N.J., USA (the “company”) includes “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of the company’s management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements. Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions. The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2025 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov). Please see Prescribing Information for PIFELTRO (doravirine) at: https://www-merck-com.libproxy1.nus.edu.sg/product/usa/pi_circulars/p/pifeltro/pifeltro_pi.pdf and Patient Information for PIFELTRO at: https://www-merck-com.libproxy1.nus.edu.sg/product/usa/pi_circulars/p/pifeltro/pifeltro_ppi.pdf Please see Prescribing Information for DELSTRIGO (doravirine, lamivudine, and tenofovir disoproxil fumarate) at: https://www-merck-com.libproxy1.nus.edu.sg/product/usa/pi_circulars/d/delstrigo/delstrigo_pi.pdf and Patient Information for DELSTRIGO at: https://www-merck-com.libproxy1.nus.edu.sg/product/usa/pi_circulars/d/delstrigo/delstrigo_ppi.pdf _______________________ ibictegravir/emtricitabine/tenofovir alafenamide (BIKTARVY) is a registered trademark of Gilead Sciences, Inc. Media Contacts: Eilyn Segura (203) 940-6259 Deb Wambold (215) 779-2234 Investor Contacts: Peter Dannenbaum (732) 594-1579 Damini Chokshi (732) 594-1577

– Novel Investigational Combination Pairs Bictegravir, a Global Guideline-Recommended Integrase Strand Transfer Inhibitor with a High Barrier to Resistance with Lenacapavir, a First-in-Class Capsid Inhibitor – – Phase 3 ARTISTRY-1 and ARTISTRY-2 Results will Inform Regulatory Filings – FOSTER CITY, Calif.--(BUSINESS WIRE)-- Gilead Sciences, Inc. (Nasdaq: GILD) today announced the presentation of new Phase 3 ARTISTRY-1 and ARTISTRY-2 trial data at CROI 2026 showing a treatment switch to an investigational, single-tablet combination regimen of bictegravir 75 mg/lenacapavir 50 mg (BIC/LEN) was effective in people living with HIV with virological suppression, including those switching from complex multi-tablet regimens or a global guideline-recommended single-tablet regimen. The novel combination of BIC/LEN was generally well tolerated, with no significant or new safety concerns identified. “The ARTISTRY trials represent the latest example of Gilead’s commitment to advancing HIV treatment through continuous scientific innovation,” said Jared Baeten, M.D., Ph.D., Senior Vice President, Clinical Development, Virology Therapeutic Area Head, Gilead Sciences. “This once-daily single-tablet regimen combines the durability of bictegravir with lenacapavir, a first‑in‑class capsid inhibitor. The novel treatment combination is designed to sustain virologic suppression for those seeking new options. We look forward to working with regulatory authorities to potentially bring this combination forward to people with HIV.” The results demonstrate the potential of BIC/LEN to broaden HIV treatment options for adults with virological suppression, offering comparable efficacy to BIKTARVY® (bictegravir 50 mg/emtricitabine 200 mg/tenofovir alafenamide 25 mg tablets, B/F/TAF), as well as to treatment with complex multi-tablet regimens. The new data, from the ARTISTRY-1 (NCT05502341) and ARTISTRY-2 (NCT06333808) trials, assessed the safety and efficacy of the once-daily single tablet regimen of BIC/LEN and were presented during late-breaker sessions at the 33rd Conference on Retroviruses and Opportunistic Infections in Denver, Colorado. The findings build on the positive topline results announced in November and December 2025. Late-breaking results from ARTISTRY-1 Results presented at CROI 2026 demonstrate that a single-tablet regimen combining BIC/LEN could offer an important new option with optimized dosing for people living with HIV with virologic suppression on a complex multi-tablet regimen. Week 48 results showed that the single-tablet regimen of BIC/LEN was noninferior to complex multi-tablet regimens in maintaining virologic suppression, with 0.8% of participants receiving BIC/LEN having HIV-1 RNA ≥ 50 copies/mL (as determined by the US FDA-defined snapshot algorithm) compared to 1.1% who remained on their complex antiretroviral regimen. CD4 cell count remained stable in both treatment groups, and no participant had emergent resistance. At Week 48, the switch to BIC/LEN from complex multi-tablet regimens was also associated with an improvement from baseline in fasting lipid parameters, with a median change in total cholesterol, -15 mg/dL, versus +2 mg/dL. Additionally, patient-reported treatment satisfaction on the HIVTSQs score increased by a mean of 7 points from baseline, with those treated with complex multi-tablet regimens reporting no change. “Pre-existing viral resistance, intolerance, contraindications, or drug-drug interactions, may prevent many people living with HIV from benefiting from guideline-recommended single-tablet antiretroviral regimens. Complex treatment regimens can pose a significant burden on people’s lives as can be seen in the ARTISTRY-1 trial where participants were taking between 2 and 11 pills per day at baseline, with ~40% taking antiretroviral therapy more than once a day,” said Chloe Orkin, MBE, Clinical Professor of Infection and Inequities at Queen Mary University of London. “Finding new effective and convenient dosing with single-tablet regimens is key to optimizing treatment, ensuring that more people can benefit from recent advances in medical research like bictegravir and lenacapavir.” BIC/LEN was generally well tolerated, with drug-related adverse events reported in 14.3% of participants who switched to BIC/LEN and 1.6% of participants who remained on complex multi-tablet regimens. A similar incidence of serious drug-related adverse events was reported in both treatment groups (0.3% BIC/LEN; 0% complex multi-tablet regimen), with discontinuations due to adverse events rare (1.6% and 0.5%, respectively). On February 25, 2026, The Lancet published the primary outcome results of the ARTISTRY-1 trial. The manuscript is titled Switch to single-tablet bictegravir/lenacapavir from a complex HIV regimen: results from ARTISTRY-1, a randomised, open-label phase 3 clinical trial. Late-breaking results from ARTISTRY-2 Results from the ARTISTRY-2 trial presented at CROI 2026 further demonstrate the potential of BIC/LEN to broaden current HIV treatment options, offering comparable efficacy to BIKTARVY, a global guideline-recommended single-tablet treatment regimen. Through Week 48, BIC/LEN was non-inferior to standard of care treatment with BIKTARVY in maintaining virologic suppression, with 1.3% of participants receiving BIC/LEN having HIV-1 RNA ≥ 50 copies/mL (as determined by the US FDA-defined snapshot algorithm) compared to 1.0% who remained on BIKTARVY. CD4 cell count remained stable, and two participants in each treatment group met the criteria for resistance analysis. Resistance analysis showed no treatment‑emergent resistance through Week 48 in three of the four participants (one BIC/LEN‑treated and both BIKTARVY‑treated participants). An isolated integrase substitution without phenotypic resistance was detected in one participant in the BIC/LEN treatment group at Week 36. No capsid mutations were detected. Switching to BIC/LEN was shown to have no significant impact on weight, with body-mass index remaining stable in both groups through 48 weeks of treatment. BIC/LEN was generally well tolerated with similar rates of drug-related adverse events reported in the BIC/LEN and BIKTARVY treatment groups (10.4% and 12.0%, respectively). No serious drug-related adverse events were reported, and discontinuations due to adverse events were low (1.6%) in both treatment groups. “The findings from ARTISTRY-2 support the potential of the bictegravir/lenacapavir regimen to expand the range of single-tablet antiretroviral treatments available to people living with HIV,” said Eric Meissner, MD, PhD, Associate Professor, Director of HIV and Hepatitis Patient Care and Research, Medical University of South Carolina. “With efficacy shown to be comparable to a guideline-recommended therapy, we look forward to the prospect of having another meaningful treatment option for adults with HIV who are virologically suppressed.” Bictegravir and lenacapavir in combination are investigational and not approved anywhere globally. The safety and efficacy of this combination use has not been established. There is currently no cure for HIV or AIDS. About ARTISTRY-1 ARTISTRY-1 (NCT05502341) is a multicenter Phase 2/3 clinical trial comparing the investigational once-daily combination of bictegravir, a global guideline-recommended integrase strand transfer inhibitor, and lenacapavir, a first-in-class capsid inhibitor, versus current therapy in people with HIV who are virologically suppressed on complex regimens. In Phase 3, participants were randomized 2:1 to receive a fixed-dose combination of bictegravir 75 mg/lenacapavir 50 mg or continue their stable baseline complex regimen. The primary endpoint was the proportion of patients with HIV-1 RNA ≥50 copies/mL at Week 48 as determined by the US FDA-defined snapshot algorithm. Key secondary endpoints at week 48 included the proportion of participants with virologic suppression (HIV viral load <50 copies/mL per US FDA snapshot), change in baseline in CD4 cell count and the proportion of participants with treatment-emergent adverse events (TEAEs). About ARTISTRY-2 ARTISTRY-2 (NCT06333808) is a multicenter, double-blind, randomized Phase 3 clinical trial comparing the safety and efficacy of an investigational once-daily combination of bictegravir and lenacapavir versus BIKTARVY in people with HIV who are virologically suppressed. Participants on BIKTARVY were randomized 2:1 to switch onto bictegravir 75 mg/lenacapavir 50 mg or continue their BIKTARVY regimen. The primary endpoint was the proportion of patients with HIV-1 RNA ≥50 copies/mL at Week 48 as determined by the US FDA-defined snapshot algorithm. Key secondary endpoints at Week 48 included the proportion of participants with virologic suppression (HIV viral load <50 copies/mL per US FDA snapshot), change from baseline in CD4 cell count and the proportion of participants with TEAEs. About Bictegravir Bictegravir is a global guideline-recommended integrase strand transfer inhibitor (INSTI) with a high barrier to resistance. INSTIs are a class of antiretroviral agents that target the viral integrase. Bictegravir is used only in combination with other antiretroviral agents in the treatment of HIV. About Lenacapavir Lenacapavir is approved in multiple countries as pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV in adults and adolescents who are at risk of HIV acquisition. Lenacapavir is also approved in multiple countries for the treatment of multi-drug-resistant HIV in adults, in combination with other antiretrovirals. The multi-stage mechanism of action of lenacapavir is distinguishable from other currently approved classes of antiretroviral agents. While most antiretrovirals act on just one stage of viral replication, lenacapavir is designed to inhibit HIV at multiple stages of its lifecycle and has no known cross resistance exhibited in vitro to other existing drug classes. Lenacapavir is being evaluated as a long-acting option in multiple ongoing and planned early and late-stage clinical studies in Gilead’s HIV prevention and treatment research program. Lenacapavir is being developed as a foundation for potential future HIV therapies with the goal of offering both long-acting oral and injectable options with several dosing frequencies, in combination or as a mono agent, that help address individual needs and preferences of people and communities affected by HIV. Lenacapavir was chosen as one of TIME’s Best Inventions, recognized on Fortune’s Change the World list, named the 2024 Breakthrough of the Year by the journal Science, and selected as the 2025 Prix Galien USA Award for Best Pharmaceutical Product. About Gilead HIV For more than 35 years, Gilead has been a leading innovator in the field of HIV, driving advances in treatment, prevention and cure research. Gilead researchers have developed 13 HIV medications, including the first single-tablet regimen to treat HIV, the first antiretroviral for pre-exposure prophylaxis (PrEP) to help reduce new HIV infections, and the first long-acting injectable HIV treatment medication administered twice-yearly. Our advances in medical research have helped to transform HIV into a treatable, preventable, chronic condition for millions of people. Gilead is committed to continued scientific innovation to provide solutions for the evolving needs of people affected by HIV around the world. Through partnerships, collaborations and charitable giving, the company also aims to improve education, expand access and address barriers to care, with the goal of ending the HIV epidemic worldwide. Gilead has been repeatedly recognized as one of the top two leading philanthropic funders of HIV-related programs in a report released by Funders Concerned About AIDS. Discover more about Gilead’s unique collaborations worldwide and the work to help end the HIV epidemic. About Gilead Sciences Gilead Sciences, Inc. is a biopharmaceutical company that has pursued and achieved breakthroughs in medicine for more than three decades, with the goal of creating a healthier world for all people. The company is committed to advancing innovative medicines to prevent and treat life-threatening diseases, including HIV, viral hepatitis, COVID-19, cancer and inflammation. In 2025, Gilead announced a planned $32 billion investment to further strengthen its U.S. footprint to power the next era of discovery, job creation and public health preparedness – while continuing to invest globally to ensure patients everywhere benefit from its scientific innovation. Gilead operates in more than 35 countries worldwide, with headquarters in Foster City, Calif. Forward-Looking Statements This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including Gilead’s ability to initiate, progress or complete clinical trials or studies within currently anticipated timelines or at all, and the possibility of unfavorable results from ongoing and additional clinical trials or studies, including those involving bictegravir and lenacapavir (such as ARTISTRY-1 and ARTISTRY-2); uncertainties relating to regulatory applications and related filing and approval timelines, including potential applications for programs and/or indications currently under evaluation, such as the combination of bictegravir and lenacapavir for HIV-1 infection, and the risk that any regulatory approvals, if granted, may be subject to significant limitations on use or subject to withdrawal or other adverse actions by the applicable regulatory authority; the possibility that Gilead may make a strategic decision to discontinue development of these programs and, as a result, these programs may never be successfully commercialized for the indications currently under evaluation; and any assumptions underlying any of the foregoing. These and other risks, uncertainties and factors are described in detail in Gilead’s Annual Report on Form 10-K for the year ended December 31, 2025, as filed with the U.S. Securities and Exchange Commission. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. The reader is cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and is cautioned not to place undue reliance on these forward-looking statements. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation and disclaims any intent to update any such forward-looking statements. BIKTARVY, Gilead and the Gilead logo are trademarks of Gilead Sciences, Inc., or its related companies. For more information about Gilead, please visit the company’s website at www.gilead.com, follow Gilead on X (@Gilead Sciences) and LinkedIn, or contact Gilead Public Affairs Priscilla White, Media public_affairs@gilead.com Jacquie Ross, Investors investor_relations@gilead.com