Gilead to Showcase Interim Long-Term Efficacy Data for Livdelzi® (Seladelpar) in Primary Biliary Cholangitis (PBC) and Investigational Bulevirtide in Chronic Hepatitis Delta

- Late-Breaking Real-World Experience of People Switching from Obeticholic Acid to Livdelzi^® to be Presented at The Liver Meeting^® 2025 -

- New Three-Year Interim Data Demonstrates Livdelzi^® May Help Stabilize or Improve Liver Health in PBC Patients -

Gilead Sciences, Inc. (NASDAQ:GILD) will present new research that reinforces its commitment to advancing innovation for people living with liver disease at The Liver Meeting^® 2025, hosted by the American Association for the Study of Liver Diseases (AASLD), November 7-11 in Washington, D.C. Key findings from more than 35 accepted abstracts across PBC and viral hepatitis will include late-breaking data and three oral presentations.

Primary Biliary Cholangitis Research

Three late-breaking presentations will share new data on Livdelzi^® (seladelpar) in people living with primary biliary cholangitis (PBC), including real-world treatment experience following the withdrawal of obeticholic acid (LB#5037), liver stiffness outcomes from a three-year interim analysis of the ongoing ASSURE study (LB#5031), and long-term pruritus data from the RESPONSE trial and its open-label extension (#LB5015). These studies explore how Livdelzi is being used in clinical practice, its potential impact on liver health, and patient-reported experiences with itch over time.

"The data we're sharing at The Liver Meeting^® reflect our continued dedication to advancing science that meaningfully improves the lives of people affected by liver disease," said Anu Osinusi, Vice President, Clinical Research for Hepatitis, Respiratory and Emerging Viruses at Gilead. "These interim long-term findings in PBC deepen our understanding of disease progression and highlight the potential to help improve patients' liver health and symptoms."

Viral Hepatitis Research

Gilead also plans to share new data from across its viral hepatitis portfolio. In hepatitis delta virus (HDV), Gilead will present integrated analyses from the MYR204 (NCT03852433) and MYR301 (NCT03852719) studies, investigating the long-term safety and efficacy of bulevirtide for the treatment of chronic HDV. Gilead will also present an analysis from the Phase 3 ALLIANCE study (NCT03547908) that aims to study HIV/HBV co-infected participants who achieved hepatitis B virus surface antigen (HBsAg) loss, a marker of HBV functional cure, after starting tenofovir-based treatments. Lastly, data from a Phase 1b study on the safety, tolerability and antiviral efficacy of GS-2829 and GS-6779, novel investigational therapeutic HBV vaccines, among virally suppressed participants with chronic hepatitis B, will be presented.

FOCUS: Gilead Commitment to Collaboration and Public Health

The FOCUS program is a public health initiative that enables partners to develop and share best practices in routine blood-borne virus (HIV, HCV, HBV) screening, diagnosis and linkage to care. Two presentations will underscore how innovative approaches and strategic partnerships are driving measurable progress to help combat viral hepatitis and HIV.

• Dr. Su Wang, from Cooperman Barnabas Medical Center, will present a model for resilient public health infrastructure through an automated electronic medical record (EMR)-based screening program. The initiative demonstrates how health systems can leverage technology to maintain robust monitoring systems, identify individuals with viral infections and offer linkage to care. This approach exemplifies how local action can help sustain national public health priorities in the face of potential decreases in federal funding.

• Meanwhile, the Kentucky Department for Public Health will share results from a pilot program that introduced point-of-care HCV RNA testing in community settings serving people who use drugs and those experiencing homelessness. By integrating rapid diagnostics into routine care, the initiative highlights how targeted implementation can help remove systemic barriers, accelerate linkage to care, and improve health equity for vulnerable populations.

Together, these efforts reflect the transformative potential of data-driven strategies and public-private collaboration in advancing public health goals and strengthening public health systems.

Gilead Commitment to Advocacy

At The Liver Meeting^® 2025, Gilead will launch Reflecting Realities^™, a campaign dedicated to capturing the emotions and real experiences of people living with liver conditions. Reflecting Realities^™ brings together two campaigns: "BehinD the SilenCe" in collaboration with the World Hepatitis Alliance (WHA) and All the Feelings with PBC^™ in collaboration with the PBC Foundation and Friends of the PBC Foundation. "BehinD the SilenCe" highlights the experiences of people living with viral hepatitis and will feature portrait photographs of people living with viral hepatitis and audio testimonials of their lived experience. These campaigns aim to showcase the real impact of liver disease and facilitate more meaningful conversations between people living with liver disease and their healthcare providers.

Additionally, Gilead will announce which independent emerging investigators Gilead has selected to participate in its Research Scholars Program in PBC. The objective of the program is to support innovative research that aims to close scientific knowledge gaps and address unmet medical needs.

For more information, including a complete list of abstract titles being presented at the meeting, please visit the AASLD website.

Key Abstracts at AASLD 2025:

About Livdelzi

Livdelzi^® is an oral PPAR-delta agonist, or delpar, for the treatment of PBC. PPAR-delta has been shown to regulate critical metabolic and liver disease pathways. Preclinical and clinical data indicate Livdelzi has anticholestatic, anti-inflammatory, antipruritic, and antifibrotic effects.

U.S. Indication for Livdelzi^®

Livdelzi is indicated for the treatment of primary biliary cholangitis (PBC) in combination with ursodeoxycholic acid (UDCA) in adults who have had an inadequate response to UDCA, or as monotherapy in patients unable to tolerate UDCA. The FDA approved this indication under accelerated approval based on a reduction of alkaline phosphatase (ALP). Improvement in survival or prevention of liver decompensation events have not been demonstrated. Continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trial(s).

Limitations of Use:

Use of Livdelzi is not recommended in patients who have or develop decompensated cirrhosis (e.g., ascites, variceal bleeding, hepatic encephalopathy).

U.S. Important Safety Information for Livdelzi

Warnings and Precautions

• Fractures: Fractures occurred in 4% of LIVDELZI-treated patients compared to no placebo-treated patients. Consider the risk of fracture in the care of patients treated with LIVDELZI and monitor bone health according to current standards of care.
• Liver Test Abnormalities: LIVDELZI has been associated with dose-related increases in serum transaminase (AST and ALT) levels > 3 x ULN in patients receiving 50 mg and 200 mg once daily (5x and 20x higher than the recommended dosage of 10 mg once daily). Perform baseline clinical and laboratory testing when starting LIVDELZI and monitor thereafter according to routine patient management. Interrupt treatment if the liver tests (ALT, AST, total bilirubin, and/or ALP) worsen, or if the patient develops signs and symptoms of clinical hepatitis (eg, jaundice, right upper quadrant pain, eosinophilia). Consider permanent discontinuation if liver tests worsen after restarting LIVDELZI.
• Biliary Obstruction: Avoid use of LIVDELZI in patients with complete biliary obstruction. If biliary obstruction is suspected, interrupt LIVDELZI and treat as clinically indicated.

Adverse Reactions

• The most common adverse reactions (≥5%) with LIVDELZI were headache (8%), abdominal pain (7%), nausea (6%), abdominal distension (6%), and dizziness (5%).

Drug Interactions

• OAT3 Inhibitors and Strong CYP2C9 Inhibitors: Avoid coadministration with LIVDELZI due to increased LIVDELZI exposure.
• Rifampin: Monitor biochemical response (e.g., ALP and bilirubin) when patients initiate rifampin during LIVDELZI treatment. Coadministration may result in delayed or suboptimal biochemical response of LIVDELZI.
• Dual Moderate CYP2C9 and Moderate-to-Strong CYP3A4 Inhibitors and BCRP Inhibitors (eg, cyclosporine): Monitor closely for adverse effects. Concomitant administration with LIVDELZI may increase LIVDELZI exposure.
• CYP2C9 Poor Metabolizers Using Moderate-to-Strong CYP3A4 Inhibitors: Monitor more frequently for adverse reactions as concomitant use of a moderate-to-strong CYP3A4 inhibitor in patients who are CYP2C9 poor metabolizers may increase LIVDELZI exposure and risk of LIVDELZI adverse reactions.
• Bile Acid Sequestrants: Administer LIVDELZI at least 4 hours before or 4 hours after taking a bile acid sequestrant, or at as great an interval as possible.

Pregnancy and Lactation

• Pregnancy: There are insufficient data from human pregnancies exposed to LIVDELZI to allow an assessment of a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Report pregnancies to Gilead Sciences, Inc., at 1-800-445-3235.
• Lactation: There are no data on the presence of LIVDELZI in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for LIVDELZI and any potential adverse effects on the breastfed infant from LIVDELZI.

Marketing Authorizations

In July 2023, the European Commission (EC) granted full Marketing Authorization (MA) for Hepcludex^® (bulevirtide) 2 mg for the treatment of adults with chronic HDV and compensated liver disease. Bulevirtide was initially granted a conditional MA from the EC in July 2020 to provide people living with HDV urgent access to treatment. Bulevirtide's conditional MA license in the UK was converted to a full MA in August 2023, and a full MA was granted in Switzerland in February 2024, in Australia in July 2024 and in Canada in August 2025. In regions where bulevirtide is not approved, including the U.S., bulevirtide 2 mg is an investigational product. In these regions, health authorities have not established the safety and efficacy of bulevirtide. Bulevirtide 10 mg is not approved anywhere globally. A Biologics License Application (BLA) for bulevirtide 10 mg was submitted to the U.S. Food and Drug Administration (FDA) on September 22, 2025, and is pending regulatory decision.

In the U.S., Livdelzi^® obtained accelerated approval for the treatment of PBC by the U.S. Food and Drug Administration (FDA) in August 2024. Livdelzi received Breakthrough Therapy Designation, as well as Orphan Drug Designation for the treatment of people living with PBC. As part of the FDA accelerated approval, Gilead has committed to AFFIRM, a long-term outcomes study, which has begun in people with compensated cirrhosis. Continued U.S. approval may be contingent upon verification of clinical benefit in confirmatory trial(s). Regulatory review for Livdelzi is underway in Australia and Switzerland. Livdelzi received conditional marketing authorization from the UK Medicines and Healthcare products Regulatory Agency (MHRA) in January 2025. In February 2025, the European Commission (EC) granted conditional marketing authorization for Lyvdelzi^® (seladelpar) for the treatment of PBC in combination with ursodeoxycholic acid (UDCA) in adults who have an inadequate response to UDCA alone, or as monotherapy in those unable to tolerate UDCA. In October 2025, Lyvdelzi received conditional marketing authorization in Canada for the treatment of primary biliary cholangitis (PBC), in combination with ursodeoxycholic acid (UDCA) in adults who have an inadequate response to UDCA alone, or as monotherapy in adults unable to tolerate UDCA.

About Gilead Sciences in Liver Disease

For decades, Gilead has pioneered the way forward to improve the lives of people living with liver disease around the world. The company has helped to transform hepatitis C from a chronic condition into a curable condition. For individuals living with hepatitis B or hepatitis delta, Gilead's focus on advancing medicines drives hope that today's research will turn into tomorrow's cures. Beyond viral hepatitis, Gilead is working to deliver advanced treatments for people living with PBC. The commitment of Gilead does not stop there. Through ground-breaking science and collaborative partnerships, the company strives to create healthier futures for everyone living with liver disease. Gilead remains devoted to a future without liver disease.

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. Gilead operates in more than 35 countries worldwide, with headquarters in Foster City, California.

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 within currently anticipated timelines or at all, and the possibility of unfavorable results from ongoing or additional clinical trials, including those involving Livdelzi/Lyvdelzi (seladelpar), bulevirtide, tenofovir alafenamide and tenofovir disoproxil fumarate (such as the ALLIANCE, ASSURE, RESPONSE, MYR204, MYR301 and any confirmatory studies); uncertainties relating to regulatory applications and related filing and approval timelines, including additional pending and potential applications for seladelpar and bulevirtide; 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; and any assumptions underlying any of the foregoing. These and other risks, uncertainties and factors are described in detail in Gilead's Quarterly Report on Form 10-Q for the quarter ended June 30, 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.

Hepcludex, Livdelzi, Lyvdelzi, All the Feelings with PBC, Gilead and the Gilead logo are trademarks of Gilead Sciences, Inc., or its related companies.

U.S. full Prescribing Information for Livdelzi^® is available at www.gilead.com.

For more information about Gilead, please visit the company's website at www.gilead.com, follow Gilead on X/Twitter (@Gilead Sciences) and LinkedIn (@Gilead-Sciences)

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Blair Baumwell, Media

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Jacquie Ross, Investors

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