Gilead to Present New Data at IAS 2021 Demonstrating the Company's Commitment to Advancing Innovation in HIV Research

Gilead Sciences, Inc. (Nasdaq: GILD) today announced the company's upcoming contributions to the 11 ^th International AIDS Society (IAS) Conference on HIV Science, taking place virtually from July 18-21. Thirty-one abstracts reflect Gilead's ongoing commitment to scientific innovation, a key pillar to addressing unmet needs in HIV treatment and prevention. Beyond presenting new scientific data from the company's HIV research and development programs, Gilead will convene a symposium featuring a diverse, global panel of leading HIV researchers and people living with HIV, to discuss potential clinical pathways to achieve a functional cure and community perspectives on the process.

"Continued scientific innovation is essential to helping end the global HIV epidemic and we are committed to advancing the next generation of therapies to improve the care of people and communities impacted by this disease," said Merdad Parsey, MD, PhD, Chief Medical Officer, Gilead Sciences. "Our data at this year's meeting demonstrate the important scientific advancements we are making to help address critical unmet needs for people with HIV and those who could benefit from PrEP medicines."

Presentations from Gilead's HIV research program will include:

• A pooled analysis of 192-week data from open-label extension periods of two Phase 3 trials evaluating the once-daily, single tablet regimen, Biktarvy ^® (bictegravir 50 mg/emtricitabine 200 mg/tenofovir alafenamide 25 mg tablets, B/F/TAF) in treatment-naïve adults living with HIV
• 72-week data from the BRAAVE trial evaluating the safety and efficacy of switching to Biktarvy in Black or African American adults who are virologically supressed
• Data from the Phase 2/3 CAPELLA trial evaluating the company's investigational, long-acting subcutaneously administered HIV-1 capsid inhibitor, lenacapavir, in heavily treatment-experienced people living with multidrug resistant HIV
• Interim Phase 2 data from the open-label CALIBRATE trial evaluating the safety and efficacy of lenacapavir as an investigational, long-acting HIV capsid inhibitor in combination with other antiretroviral agents in treatment-naïve people living with HIV
• Data from a Phase 1b trial examining the impact from the investigational TLR7 agonist, vesatolimod, between certain immune responses in people living with HIV on antiretroviral therapy
• Prevention research, including data exploring adherence to PrEP medicines among new PrEP users initiating Descovy (emtricitabine 200 mg/tenofovir alafenamide 25 mg) for PrEP ^® , real-world utilization of PrEP medicines during the COVID-19 pandemic and the safety and efficacy profile of Descovy for PrEP, as well as the use of novel study designs for HIV prevention trials

Select accepted abstracts are as follows:

For more information, including a complete list of abstracts, please visit: https://www.ias2021.org/the-programme .

Please see below for U.S. Indications and Important Safety Information, including Boxed Warnings, for Biktarvy ^® and Descovy for PrEP ^® .

Lenacapavir and vesatolimod are investigational compounds and are not approved by the U.S. Food & Drug Administration or any regulatory authority for any use. Their safety and efficacy have not been established. In May 2019, FDA granted Breakthrough Therapy Designation for the development of lenacapavir for the treatment of HIV-1 infection in heavily treatment-experienced patients with multi-drug 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.

There is currently no cure for HIV or AIDS.

U.S. Indication for Biktarvy

Biktarvy is indicated as a complete regimen for the treatment of HIV-1 infection in adults and pediatric patients weighing at least 25 kg who have no antiretroviral (ARV) treatment history or to replace the current ARV regimen in those who are virologically suppressed (HIV-1 RNA

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: Patients weighing ≥25 kg: 1 tablet taken once daily with or without food.
• Renal impairment: 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 Descovy for PrEP

Descovy for PrEP is indicated in at-risk adults and adolescents (≥35 kg) to reduce the risk of sexually acquired HIV-1 infection, excluding individuals at risk from receptive vaginal sex. HIV-1–negative status must be confirmed immediately prior to initiation.

Limitation of Use:

• Descovy for PrEP is not indicated in individuals at risk of HIV-1 from receptive vaginal sex because effectiveness in this population has not been evaluated.

U.S. Important Safety Information and Indication for Descovy for PrEP

BOXED WARNING: RISK OF DRUG RESISTANCE WITH USE OF DESCOVY FOR PrEP IN UNDIAGNOSED EARLY HIV-1 INFECTION and POST TREATMENT ACUTE EXACERBATION OF HEPATITIS B

• Descovy for PrEP must be prescribed only to patients confirmed to be HIV negative immediately prior to initiation and at least every 3 months during use. Drug-resistant HIV-1 variants have been identified with use of emtricitabine/tenofovir disoproxil fumarate
• (FTC/TDF) for HIV-1 PrEP following undetected acute HIV-1 infection. Do not initiate if signs or symptoms of acute HIV-1 infection are present unless HIV-negative status is confirmed.
• Severe acute exacerbations of hepatitis B have been reported in patients infected with hepatitis B virus (HBV) who discontinued products containing FTC and/or TDF and may occur with discontinuation of Descovy. Closely monitor hepatic function with both clinical and laboratory follow-up for at least several months in patients with HBV who discontinue Descovy. If appropriate, anti-hepatitis B therapy may be warranted.

Contraindication:

• Descovy for PrEP is contraindicated in patients with unknown or positive HIV status.

Comprehensive management to reduce risks:

• Use Descovy for PrEP to reduce the risk of HIV-1 infection as part of a comprehensive strategy that includes adherence to daily dosing and safer sex practices, including condoms, to reduce the risk of sexually transmitted infections (STIs).
• HIV-1 risk factors: Behavioral, biological, or epidemiologic HIV-1 risk factors may include, but are not limited to: condomless sex, past or current STIs, self-identified HIV risk, having sexual partners of unknown HIV-1 viremic status, or sexual activity in a high-prevalence area or network.
• Reduce STI risk: Counsel on the use of STI prevention measures (e.g., consistent and correct condom use, knowledge of partner's HIV-1 viremic status, regular testing for STIs).
• Reduce potential for drug resistance: Only prescribe Descovy for PrEP to patients confirmed to be HIV negative immediately prior to initiation, at least every 3 months while taking Descovy, and upon an STI diagnosis. HIV-1 resistance substitutions may emerge in patients with undetected HIV-1 infection who are taking only Descovy because Descovy alone is not a complete regimen for treating HIV-1.
  • Some HIV tests may not detect acute HIV infection. Prior to initiating Descovy for PrEP, ask patients about potential recent exposure events. If recent (
  • If HIV-1 infection is suspected or if symptoms of acute infection are present while taking Descovy for PrEP, convert the Descovy for PrEP regimen to a complete HIV treatment regimen until HIV-negative status is confirmed by a test approved by the FDA for use in the diagnosis of acute HIV infection.
• Counsel on adherence: Counsel patients to strictly adhere to daily dosing, as efficacy is strongly correlated with adherence. Some patients, such as adolescents, may benefit from more frequent visits and counseling.

Warnings and precautions:

• New onset or worsening renal impairment: Cases of acute renal failure and Fanconi syndrome have been reported with the use of tenofovir prodrugs. Do not initiate Descovy in patients with estimated creatinine clearance (CrCl)

• Lactic acidosis and severe hepatomegaly with steatosis: Fatal cases have been reported with the use of nucleoside analogs, including FTC and TDF. Discontinue use 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 (≥2%) in the Descovy for PrEP clinical trial were diarrhea, nausea, headache, fatigue, and abdominal pain.

Drug interactions:

• Prescribing information: Consult the full Prescribing Information for Descovy for more information, warnings, and potentially significant drug interactions, including clinical comments.
• Metabolism: Drugs that inhibit P-gp can increase the concentrations of tenofovir alafenamide (TAF), a component of Descovy. Drugs that induce P-gp can decrease the concentrations of TAF, which may lead to loss of efficacy.
• Drugs affecting renal function: Coadministration of Descovy 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: One tablet taken once daily with or without food.
• HIV screening: Test for HIV-1 infection immediately prior to initiating, at least every 3 months during use, and upon diagnosis of an STI (see Warnings and Precautions section).
• HBV screening: Test for HBV infection prior to or when initiating Descovy.
• Renal impairment and monitoring: Not recommended in patients with creatinine clearance (CrCl)

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 or studies within currently anticipated timelines or at all, including those involving Biktarvy, Descovy for PrEP, lenacapavir and vesatolimod; the possibility of unfavorable results from such ongoing and additional clinical trials; the possibility that Gilead may make a strategic decision to discontinue development of lenacapavir and vesatolimod and as a result, these compounds may never be successfully commercialized; Gilead's ability to receive regulatory approvals in a timely manner or at all, including marketing approvals of lenacapavir and vesatolimod, and the risk that any such approvals, if granted, may have significant limitations on its 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 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. 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 for PrEP, including BOXED WARNINGS , are available at www.gilead.com .

Biktarvy, Descovy for PrEP, 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 ( @Gilead Sciences ) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

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