Clinical and Patient-Reported Outcomes in People Living With HIV on Biktarvy® in Observational BICSTaR Study Demonstrate Consistent Efficacy Profile in Real-World Setting

Clinical Data Across a Diverse Range of People Living With HIV on Biktarvy Treatment in the International BICSTaR Study Showed High Effectiveness and High Levels of Adherence –

– Long-Term Switch Data Presented at EACS 2021 Further Establish the Robust and Durable Efficacy Profile of Biktarvy –

Gilead Sciences, Inc. (Nasdaq: GILD) today announced interim results from the ongoing, multinational, observational single-arm, non-comparative real-world cohort BICSTaR study, which is designed to evaluate the antiviral effectiveness and safety profile of Biktarvy® (bictegravir 50 mg/emtricitabine 200 mg/tenofovir alafenamide 25 mg tablets, B/F/TAF) in 1,135 people living with HIV. The BICSTaR study also collected patient-reported outcomes in routine clinical practice to better understand the impact of treatment on health-related quality of life in people living with HIV. These data were presented at the 18th European AIDS Conference (EACS 2021).

Gilead presented an analysis of patient-reported outcomes after 12 months of treatment with Biktarvy from the BICSTaR study. During the study, conducted at sites in Europe, Canada and Israel, people living with HIV who initiated treatment with Biktarvy between June 2018 and September 2020 completed questionnaires at baseline and 12 months. The questionnaires assessed patient-reported outcomes covering a range of measures. The results underline the importance of collecting patient-reported outcomes in order to understand the impact on mental health status, health-related quality of life and treatment satisfaction of people living with HIV.

"Despite advances in antiretroviral therapy, people living with HIV experience burdensome multidimensional symptoms and concerns requiring person-centered care," said Fernando Bognar, MD, Vice President, Medical Affairs, HIV at Gilead Sciences. "The patient-reported outcomes observed in the BICSTaR study provide a first-hand assessment of the impact of HIV treatment and care on the quality of life that people living with HIV experience. As physicians and people living with HIV look to understand what long-term treatment means to them individually, these data presented at EACS also reinforce that Biktarvy can meet the specific treatment needs of diverse groups of people, including men and women aging with HIV and those with existing comorbid conditions."

In a second analysis of the BICSTaR study, 97% (n=149/154) of treatment-naïve adults and 96% (n=771/800) of treatment-experienced adults achieved and maintained virologic suppression (HIV-1 RNA

Additional Biktarvy data presented at EACS 2021 include a Phase 3 trial (Study 1878) that demonstrated the durable efficacy of Biktarvy. In the study, 99% of people living with HIV who switched to Biktarvy from a boosted protease inhibitor-based regimen maintained and achieved long-term viral suppression through a median of 101 weeks (n=525/532), including 98% of participants with pre-existing resistance (n=212/217; median of 108 weeks) and 98% of participants with viral blips (n=39/40; median of 109 weeks), with no treatment-emergent resistance to Biktarvy. A pooled analysis of five Phase 3 studies (1844, 1878, 4030, 4449, 4580) also found that regardless of pre-existing TAMS (thymidine analog-associated mutations M41L, D67N, K70R, L210W, T215Y/F, and K219Q/E), a high proportion of those on Biktarvy were able to maintain virologic suppression and had an absence of treatment-emergent resistance. These data support the continued evaluation of Biktarvy as a potential option for virologically suppressed people living with HIV with known resistance. The use of Biktarvy in individuals with a history of treatment failure or known resistance to the components of Biktarvy is investigational, and the safety and efficacy of Biktarvy for this use have not been established.

Please see below for the U.S. Indication and Important Safety Information, including Boxed Warning, for Biktarvy.

There is currently no cure for HIV or AIDS.

About BICSTaR

The Bictegravir Single Tablet Regimen (BICSTaR) Study is an ongoing, multinational, observational single-arm, non-comparative real-world cohort study, which aims to evaluate the effectiveness, safety, tolerability, and patient-reported outcomes of treatment with Biktarvy in treatment‐naïve and treatment‐experienced people living with HIV. Among the people living with HIV enrolled in the BICSTaR study, there is a high baseline prevalence of comorbidities.

About Biktarvy

Biktarvy is a complete HIV-1 treatment that combines three powerful medicines to form the smallest integrase strand transfer inhibitor (INSTI)-based single-tablet regimen (STR) available, offering simple once-daily dosing with or without food, with a limited drug interaction potential and a high barrier to resistance. Biktarvy combines the novel, unboosted INSTI bictegravir, with the Descovy ^® (emtricitabine 200 mg/tenofovir alafenamide 25 mg tablets, F/TAF) backbone. Biktarvy is a complete single-tablet regimen and should not be taken with other HIV-1 medicines.

In February 2018, the U.S. Food and Drug Administration (FDA) approved Biktarvy (bictegravir 50 mg/emtricitabine 200 mg/tenofovir alafenamide 25 mg tablets, B/F/TAF) as a once-daily single-tablet regimen for the treatment of HIV-1 infection in adults. In June 2019, the FDA approved labeling revisions to Biktarvy, expanding the patient population to include pediatric patients weighing at least 25 kg. In October 2021, the FDA approved a new low-dose tablet formulation of Biktarvy (bictegravir 30 mg/emtricitabine 120 mg/tenofovir alafenamide 15 mg tablets) for pediatric patients weighing at least 14 kg to less than 25 kg. For all patient populations, Biktarvy is only indicated for the treatment of HIV-1 infection in people who have no antiretroviral treatment history or to replace the current antiretroviral regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no history of treatment failure and no known substitutions associated with resistance to the individual components of Biktarvy.

U.S. Important Safety Information for Biktarvy

BOXED WARNING: POST TREATMENT ACUTE EXACERBATION OF HEPATITIS B

• Severe acute exacerbations of hepatitis B have been reported in patients who are coinfected with HIV-1 and HBV and have discontinued products containing emtricitabine (FTC) and/or tenofovir disoproxil fumarate (TDF), and may occur with discontinuation of BIKTARVY. Closely monitor hepatic function with both clinical and laboratory follow-up for at least several months in patients who are coinfected with HIV-1 and HBV and discontinue BIKTARVY. If appropriate, anti-hepatitis B therapy may be warranted.

Contraindications

• Coadministration: Do not use BIKTARVY with dofetilide or rifampin.

Warnings and precautions

• Drug interactions: See Contraindications and Drug Interactions sections. Consider the potential for drug interactions prior to and during BIKTARVY therapy and monitor for adverse reactions.
• Immune reconstitution syndrome, including the occurrence of autoimmune disorders with variable time to onset, has been reported.
• 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 tenofovir alafenamide (TAF)–containing products. Do not initiate BIKTARVY in patients with estimated creatinine clearance (CrCl) Renal monitoring: Prior to or when initiating BIKTARVY and during therapy, assess serum creatinine, CrCl, urine glucose, and urine protein in all patients as clinically appropriate. In patients with chronic kidney disease, assess serum phosphorus.
• Lactic acidosis and severe hepatomegaly with steatosis: Fatal cases have been reported with the use of nucleoside analogs, including FTC and TDF. Discontinue BIKTARVY 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 diarrhea (6%), nausea (6%), and headache (5%).

Drug interactions

• Prescribing information: Consult the full prescribing information for BIKTARVY for more information on Contraindications, Warnings, and potentially significant drug interactions, including clinical comments.
• Enzymes/transporters: Drugs that induce P-gp or induce both CYP3A and UGT1A1 can substantially decrease the concentration of components of BIKTARVY. Drugs that inhibit P-gp, BCRP, or inhibit both CYP3A and UGT1A1 may significantly increase the concentrations of components of BIKTARVY. BIKTARVY can increase the concentration of drugs that are substrates of OCT2 or MATE1.
• Drugs affecting renal function: Coadministration of BIKTARVY with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of FTC and tenofovir and the risk of adverse reactions.

Dosage and administration

• Dosage: Adult and pediatric patients weighing ≥25 kg: 1 tablet containing 50 mg bictegravir (BIC), 200 mg emtricitabine (FTC), and 25 mg tenofovir alafenamide (TAF) taken once daily with or without food. Pediatric patients weighing ≥14 kg to
• Renal impairment: For patients weighing ≥25 kg, not recommended in patients with CrCl 15 to
• Hepatic impairment: Not recommended in patients with severe hepatic impairment.
• Prior to or when initiating: Test patients for HBV infection.
• Prior to or when initiating, and during treatment: As clinically appropriate, assess serum creatinine, CrCl, urine glucose, and urine protein in all patients. In patients with chronic kidney disease, assess serum phosphorus.

Pregnancy and lactation

• Pregnancy: There is insufficient human data on the use of BIKTARVY during pregnancy. Dolutegravir, another integrase inhibitor, has been associated with neural tube defects. Discuss the benefit-risk of using BIKTARVY during pregnancy and conception. An Antiretroviral Pregnancy Registry (APR) has been established. Available data from the APR for FTC shows no difference in the rates of birth defects compared with a US reference population.
• Lactation: Women infected with HIV-1 should be instructed not to breastfeed, due to the potential for HIV-1 transmission.

U.S. Indication for Biktarvy

Biktarvy is indicated as a complete regimen for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in adults and pediatric patients weighing at least 14 kg who have no antiretroviral treatment history or to replace the current antiretroviral regimen in those who are virologically-suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no history of treatment failure and no known substitutions associated with resistance to the individual components of Biktarvy.

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.

For more than 30 years, Gilead has been a leading innovator in the field of HIV, driving advances in treatment, prevention and cure research. Gilead researchers have developed eleven HIV medications , including the first single tablet regimen to treat HIV and the first once-daily oral antiretroviral tablet for pre-exposure prophylaxis (PrEP) to reduce the risk of acquiring HIV infection. These advances in medical research have helped to transform HIV into a 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 and collaborations, the company also aims to improve education, expand access and address barriers to care, with the goal of ending the HIV epidemic for everyone, everywhere.

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, including those involving Biktarvy; the possibility of unfavorable results from ongoing and additional clinical trials, including those involving Biktarvy; Gilead's ability to receive FDA and other regulatory approvals for additional indications for Biktarvy, and the risk that any such approvals, if granted, may have significant limitations on its use; the risk that physicians may not see the benefits of prescribing Biktarvy; 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.

U.S. full Prescribing Information for Biktarvy and Descovy, including BOXED WARNINGS , are available at www.gilead.com .

Biktarvy, Descovy, Gilead and the Gilead logo are registered trademarks of Gilead Sciences, Inc., or its related companies. All other trademarks are the property of their respective owner(s).

For more information about Gilead, please visit the company's website at www.gilead.com , follow Gilead on Twitter ( @Gilead Sciences ) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

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