Gilead to Present Data From Liver Disease Development Programs at The Liver Meeting®

More than 30 Abstracts Across HDV, HCV, HBV, NASH and PSC Reflect Gilead's Ongoing Commitment to Addressing Challenges Facing People Living With Liver Diseases –

Gilead Sciences, Inc. (Nasdaq: GILD) today announced the presentation of new clinical and real-world data at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting ^® , taking place from November 12-15. Presentations include the impact of treatment with bulevirtide, an investigational treatment for people with chronic hepatitis delta virus (HDV) in the U.S. that is conditionally approved in Europe, real-world data on global efforts to support the World Health Organization's goal of hepatitis C (HCV) elimination and long-term results from ongoing studies in the treatment of chronic hepatitis B infection (HBV).

"We are relentlessly working to improve upon innovative therapies to meet the unmet needs of people living with challenging liver diseases, including HDV where there is a significant unmet need," said Merdad Parsey, MD, PhD, Chief Medical Officer, Gilead Sciences. "We're excited to share data from our robust clinical development programs at AASLD's The Liver Meeting ^® , including the latest data demonstrating the positive impacts of bulevirtide for people living with HDV."

Hepcludex ^® (bulevirtide) has been granted PRIority MEdicines (PRIME) scheme eligibility by the European Medicines Agency (EMA) for the treatment of HDV infection and Breakthrough Therapy designation by the U.S. Food and Drug Administration (FDA). Bulevirtide is an investigational agent in the U.S. and its safety and efficacy have not been established.

Patient Impact of HDV Treatment

HDV infection (which is always associated with HBV infection) leads to a more rapid progression to liver fibrosis, cirrhosis, hepatic decompensation and an increased risk of liver cancer and death compared to HBV mono-infection. Gilead will present the latest findings from a Phase 3 trial that evaluated patient reported outcomes following treatment with bulevirtide after 24 weeks, demonstrating that people reported improvements in general health, bodily pain, vitality and social and emotional functioning compared to those in the delayed treatment arm of this study (Poster of Distinction 680).

Meeting the Needs of Key Populations Living With HCV

To achieve HCV elimination, people living with HCV globally need to be able to access effective and well-tolerated treatment alongside their other medications. Data will be presented on the safety and efficacy of Epclusa ^® (400 mg sofosbuvir/100 mg velpatasvir) in a broad range of people, including those with co-morbidities (PO-0940, 0927). An additional study evaluates the outcomes of tailored strategies and innovative approaches in efforts to engage people who inject drugs in HCV care (OS-97). The U.S. product label for Epclusa contains a BOXED WARNING for the risk of hepatitis B reactivation in HCV/HBV co-infected patients. See below for U.S. Important Safety Information.

Long-term Treatment With Vemlidy in HBV

In HBV, Gilead continues to expand upon the established safety and efficacy profile of Vemlidy ^® (tenofovir alafenamide 25mg, TAF) with data demonstrating a sustained virological response in heavily pre-treated patients with multidrug-resistant HBV for up to 144 weeks (PO-812). Additional data evaluate treatment with Vemlidy in a variety of special patient populations, including people living post-liver transplant with chronic kidney disease and pregnant and breastfeeding women (PO-803, 772). In another analysis, treatment with Vemlidy compared to tenofovir disoproxil fumarate (TDF) revealed a similar low risk for atherosclerotic cardiovascular disease (ASCVD) using a validated risk calculator, despite differences in their fasting lipid profiles (PO-771).

Vemlidy is indicated for the treatment of chronic HBV in adults with compensated liver disease. The use of Vemlidy for other patient populations is investigational, and the safety and efficacy for these uses have not been established. The U.S. full Prescribing Information for Vemlidy contains a BOXED WARNING for post-treatment severe acute exacerbation of hepatitis B. See below for U.S. Important Safety Information.

Liver Fibrosis

Gilead will present findings from an analysis of the associations between weight loss and changes in clinical and histologic parameters and disease progression in patients with bridging fibrosis (F3) and compensated cirrhosis (F4) due to nonalcoholic steatohepatitis (NASH). Results indicate that people with >5% weight loss over 48 weeks were more likely to achieve NASH resolution, but liver fibrosis improvement was comparable to those with

Gilead will also present results from a Phase 2, 96-week, open-label extension study evaluating cilofexor, an investigational agent, for the treatment of primary sclerosing cholangitis (PSC), a chronic cholestatic liver disease with limited treatment options for patients and significant unmet needs (OS-2155). Cilofexor is also being evaluated in the ongoing Phase 3 PRIMIS study of patients with PSC without cirrhosis.

Cilofexor is an investigational compound and is not approved by the FDA; its safety and efficacy have not been established.

Key Accepted Abstracts Being Presented at The Liver Meeting ^® Include:

For more information, including a complete list of abstract titles being presented at the meeting, please visit: https://www.aasld.org/the-liver-meeting/schedule-and-speakers .

Please see below for the U.S. Indications and Important Safety Information, including BOXED WARNINGS, for Epclusa and Vemlidy.

U.S. Important Safety Information and Indication for Epclusa

BOXED WARNING: RISK OF HEPATITIS B VIRUS REACTIVATION IN HCV/HBV COINFECTED PATIENTS

Test all patients for evidence of current or prior hepatitis B virus (HBV) infection before initiating treatment with EPCLUSA. HBV reactivation has been reported in HCV/HBV coinfected patients who were undergoing or had completed treatment with HCV direct acting antivirals (DAAs) and were not receiving HBV antiviral therapy. Some cases have resulted in fulminant hepatitis, hepatic failure, and death. Cases have been reported in patients who are HBsAg positive, in patients with serologic evidence of resolved HBV, and also in patients receiving certain immunosuppressant or chemotherapeutic agents; the risk of HBV reactivation associated with treatment with HCV DAAs may be increased in patients taking these other agents. Monitor HCV/HBV coinfected patients for hepatitis flare or HBV reactivation during HCV treatment and post-treatment follow-up. Initiate appropriate patient management for HBV infection as clinically indicated.

Contraindications

• If EPCLUSA is used in combination with ribavirin (RBV), all contraindications, warnings and precautions, in particular pregnancy avoidance, and adverse reactions to RBV also apply. Refer to RBV prescribing information.

Warnings and Precautions

• Serious Symptomatic Bradycardia When Coadministered with Amiodarone: Amiodarone is not recommended for use with EPCLUSA due to the risk of symptomatic bradycardia, particularly in patients also taking beta blockers or with underlying cardiac comorbidities and/or with advanced liver disease. A fatal cardiac arrest was reported in a patient taking amiodarone who was coadministered a sofosbuvir containing regimen. In patients without alternative, viable treatment options, cardiac monitoring is recommended. Patients should seek immediate medical evaluation if they develop signs or symptoms of bradycardia.
• Risk of Reduced Therapeutic Effect Due to Use with P-gp Inducers and/or Moderate to Strong Inducers of CYP2B6, CYP2C8 or CYP3A4: Rifampin, St. John's wort and carbamazepine are not recommended for use with EPCLUSA as they may significantly decrease sofosbuvir and/or velpatasvir plasma concentrations.

Adverse Reactions

• The most common adverse reactions (≥10%, all grades) with EPCLUSA in adults and pediatric patients 6 years of age and older were headache and fatigue; and when used with RBV in adults with decompensated cirrhosis were fatigue, anemia, nausea, headache, insomnia and diarrhea. The most common adverse reactions (≥10%, grade 1 or 2) in pediatric patients less than 6 years of age were vomiting and spitting up the drug.

Drug Interactions

• Coadministration of EPCLUSA is not recommended with topotecan due to increased concentrations of topotecan.
• Coadministration of EPCLUSA is not recommended with proton-pump inhibitors, phenobarbital, phenytoin, rifabutin, rifapentine, efavirenz, and tipranavir/ritonavir due to decreased concentrations of sofosbuvir and/or velpatasvir.

Consult the full Prescribing Information for EPCLUSA for more information on potentially significant drug interactions, including clinical comments.

Indication

EPCLUSA is indicated for the treatment of adult and pediatric patients 3 years of age and older with chronic hepatitis C virus genotype 1, 2, 3, 4, 5, or 6 infection without cirrhosis or with compensated cirrhosis and in combination with ribavirin for those with decompensated cirrhosis.

U.S. Important Safety Information and Indication for Vemlidy

BOXED WARNING: POST TREATMENT SEVERE ACUTE EXACERBATION OF HEPATITIS B

Discontinuation of anti-hepatitis B therapy, including VEMLIDY, may result in severe acute exacerbations of hepatitis B. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue anti-hepatitis B therapy, including VEMLIDY. If appropriate, resumption of anti-hepatitis B therapy may be warranted.

Warnings and Precautions

• Risk of Development of HIV-1 Resistance in HBV/HIV-1 Coinfected Patients: Due to this risk, VEMLIDY alone should not be used for the treatment of HIV-1 infection. Safety and efficacy of VEMLIDY have not been established in HBV/HIV-1 coinfected patients. HIV antibody testing should be offered to all HBV-infected patients before initiating therapy with VEMLIDY, and, if positive, an appropriate antiretroviral combination regimen that is recommended for HBV/HIV-1 coinfected patients should be used.
• New Onset or Worsening Renal Impairment: Postmarketing cases of renal impairment, including acute renal failure, proximal renal tubulopathy (PRT), and Fanconi syndrome have been reported with TAF-containing products. Patients with impaired renal function and/or taking nephrotoxic agents (including NSAIDs) are at increased risk of renal-related adverse reactions. Discontinue VEMLIDY in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome. Monitor renal function in all patients – See Dosage and Administration.
• Lactic Acidosis and Severe Hepatomegaly with Steatosis: Fatal cases have been reported with the use of nucleoside analogs, including tenofovir disoproxil fumarate (TDF). Discontinue VEMLIDY if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity develop, including hepatomegaly and steatosis in the absence of marked transaminase elevations.

Adverse Reactions

• Most common adverse reactions (incidence ≥5%; all grades) in clinical studies through week 144 were headache, upper respiratory tract infection, abdominal pain, cough, back pain, arthralgia, fatigue, nausea, diarrhea, dyspepsia, and pyrexia.

Drug Interactions

• Coadministration of VEMLIDY with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of tenofovir and the risk of adverse reactions.
• Coadministration of VEMLIDY is not recommended with the following: oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine, or St. John's wort. Such coadministration is expected to decrease the concentration of tenofovir alafenamide, reducing the therapeutic effect of VEMLIDY. Drugs that strongly affect P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) activity may lead to changes in VEMLIDY absorption.
• Consult the full prescribing information for VEMLIDY for more information on potentially significant drug interactions, including clinical comments.

Dosage and Administration

• Testing Prior to Initiation: HIV infection.
• Prior to or When Initiating, and During Treatment: On a clinically appropriate schedule, assess serum creatinine, estimated creatinine clearance, urine glucose, and urine protein in all patients. In patients with chronic kidney disease, also assess serum phosphorus.
• Dosage in Adults: 1 tablet taken once daily with food.
• Renal Impairment: Not recommended in patients with end stage renal disease (ESRD; eCrCl
• Hepatic Impairment: Not recommended in patients with decompensated (Child-Pugh B or C) hepatic impairment.

Indication

VEMLIDY is indicated for the treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver disease.

About Gilead Sciences in Liver Disease

For more than 20 years, Gilead has sought to address some of the biggest challenges in liver disease. The company has transformed the trajectory of many liver diseases through a relentless pursuit of innovation and pioneering access programs to bring meaningful therapies to people around the world. More work is required, and Gilead is committed to advancing innovative therapeutics to address the most pressing unmet needs in liver disease and overcoming barriers to better care.

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 and cancer. 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 or studies within currently anticipated timelines or at all, including those involving bulevirtide, Epclusa, Vemlidy and cilofexor; the possibility of unfavorable results from ongoing or additional clinical trials or studies, including those involving bulevirtide, Epclusa, Vemlidy and cilofexor; the possibility that Gilead may make a strategic decision to discontinue development of cilofexor and other investigational compounds and as a result, the compounds may never be successfully commercialized; Gilead's ability to receive regulatory approvals in a timely manner or at all, including FDA or EMA approval of Hepcludex, and the risk that any such approvals may be subject to significant limitations on use; 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 September 30, 2021, 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 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.

Epclusa, Hepcludex, Vemlidy, Gilead and the Gilead logo are registered 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 Twitter (@GileadSciences) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

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