U.S. Food and Drug Administration Approves New Formulation of Epclusa®, Expanding Pediatric Indication to Treat Children Ages 3 and Older With Chronic Hepatitis C

– New Oral Pellet Formulation Enables Treatment in Early Childhood with Pangenotypic, Panfibrotic Regimen –

Gilead Sciences, Inc. (Nasdaq: GILD) announced today that the U.S. Food and Drug Administration (FDA) has approved an expansion of the pediatric indication of Epclusa^® (sofosbuvir/velpatasvir) for the treatment of chronic hepatitis C virus (HCV) to now include children as young as 3 years of age, regardless of HCV genotype or liver disease severity. The FDA approved a New Drug Application (NDA) for two strengths of an oral pellet formulation of Epclusa (sofosbuvir 200 mg/velpatasvir 50 mg and sofosbuvir 150 mg/velpatasvir 37.5 mg) developed for use by younger children who cannot swallow tablets. The recommended dosage of Epclusa in children ages 3 years and older is based on weight.

Treatment with Epclusa for 12 weeks was approved in patients without cirrhosis or with compensated cirrhosis (Child-Pugh A), and in combination with ribavirin (RBV) for patients with decompensated cirrhosis (Child-Pugh B or C). Sofosbuvir/velpatasvir is the only protease inhibitor-free, pangenotypic HCV regimen approved for patients as young as 3 years of age.

In the United States, as of 2018 there were approximately 35,300 to 60,500 children living with HCV and incidence has been on the rise. Mother-to-child transmission, the most common cause of HCV infection in children, increased 161% from 2009 to 2017, with intravenous drug use representing the primary driver of HCV infection among women of childbearing age.

“Gilead remains steadfast in our commitment to supporting HCV elimination. Today’s decision by the FDA represents important progress toward that goal by expanding more cure options for children living with HCV,” said Merdad Parsey, MD, PhD, Chief Medical Officer, Gilead Sciences. “This approval adds to the robust clinical evidence supporting the safety and efficacy of Epclusa across a broad set of patients, including those with end-stage renal disease and all stages of fibrosis.”

The approval of Epclusa for children as young as 3 years of age is based on data from a Phase 2, open-label clinical trial that enrolled 41 children 3 years to less than 6 years of age to be treated with Epclusa for 12 weeks. At 12 weeks after treatment completion, Epclusa achieved a sustained virologic response (SVR12) or cure rate of 83% (34/41) among all patients, 88% (28/32) in children with HCV genotype 1, 50% (3/6) in children with HCV genotype 2, and 100% in children with HCV genotype 3 (2/2) and HCV genotype 4 (1/1). Of the seven patients who did not achieve cure, all discontinued treatment within one to 20 days of starting treatment.

The safety profile of Epclusa in children 3 to less than 6 years of age treated was generally consistent with that observed in clinical trials in adults. Vomiting and product use issue (spitting up the drug) were reported in 15% and 10% of subjects, respectively; these adverse reactions were mild (Grade 1 or 2) and led to treatment discontinuation in 5 (12%) subjects.

Please see below for the U.S. Indication and Important Safety Information, including BOXED WARNING, for Epclusa.

“Treating pediatric HCV remains an important public health priority. The Phase 2 clinical trial results previously showed that this medication was effective in treating many HCV-infected patients, regardless of genotype,” said Karen Murray, MD, Chair of Cleveland Clinic Children’s and lead investigator of the pediatric study. “Now, the expanded approval and oral pellet formulation offer new treatment strategies in younger patients with HCV.”

U.S. IMPORTANT SAFETY INFORMATION AND INDICATION FOR THE USE OF 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.

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 the risk that physicians may not see the benefits of prescribing Epclusa for the treatment of chronic HCV infection and the possibility of unfavorable results from ongoing and additional clinical studies involving Epclusa. These and other risks, uncertainties and other factors are described in detail in Gilead’s Quarterly Report on Form 10-Q for the quarter ended March 31, 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.

Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and are 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.