Gilead Sciences Presents Data Supporting a Potential Six-Month Dosing Interval for Investigational HIV-1 Capsid Inhibitor Lenacapavir (GS-6207)

Gilead Sciences, Inc. (Nasdaq: GILD) today announced data from an ongoing Phase 1 study, which showed that a sustained-delivery subcutaneous formulation of the company's investigational, novel inhibitor of HIV-1 capsid function, lenacapavir (GS-6207), sustained predicted therapeutic concentrations for at least six months following a single 900 mg dose. In the study, lenacapavir was generally well-tolerated, and no serious adverse events were reported. These data were presented at the 23rd International AIDS Conference (AIDS 2020: Virtual).

"Long-acting antiretroviral therapy may help address challenges with treatment adherence and treatment fatigue, providing additional options to people living with HIV," said Eric S. Daar, MD, Chief of the Division of HIV Medicine at the Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center and Professor of Medicine at the David Geffen School of Medicine at UCLA. "The promising safety and pharmacokinetic profiles of lenacapavir support continued evaluation of an every six-month dosing interval and further demonstrate the potential for a single subcutaneous injection of lenacapavir to be part of a long-acting HIV treatment regimen."

Lenacapavir is an investigational agent that is being developed as a component of a long-acting regimen in combination with other antiretroviral agents. Lenacapavir disrupts HIV capsid, a multimeric shell that is essential to viral replication, at multiple stages throughout the viral life cycle. In May 2019, the 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 in combination with other antiretroviral drugs.

"There is a compelling unmet need for interventions that can potentially improve treatment adherence to chronic HIV therapy, including the development of long-acting formulations, which can be administered less frequently," said Diana Brainard, MD, Senior Vice President and Virology Therapeutic Area Head, Gilead Sciences. "We hope to make HIV a more manageable part of people's lives through continued treatment innovations, including the exploration of dosing intervals that coincide with regularly scheduled visits with healthcare providers."

The safety, efficacy and dosing of lenacapavir are being evaluated in multiple ongoing clinical studies, and have not yet been established. Initial data from Phase 1 studies that assessed the antiviral activity of lenacapavir were presented at the 17th European AIDS Conference (EACS) in Basel, Switzerland in 2019 and presented at the Conference on Retroviruses and Opportunistic Infections (CROI) 2020 in Boston, Mass.

Data presented on lenacapavir at AIDS 2020: Virtual:

Virtual Poster PEB0265: GS-6207 Sustained Delivery Formulation Supports 6-Month Dosing Interval

In this ongoing, randomized, blinded, placebo-controlled, single-ascending dose (SAD) Phase 1 study, 30 participants were randomized (4:1) to receive 300 mg/mL of subcutaneous lenacapavir (n=eight per cohort) or placebo (n=two per cohort), at 300 mg (1 x 1.0 mL) or 900 mg (3 x 1.0 mL or 2 x 1.5 mL). All study participants completed dosing, and pharmacokinetic and safety data were collected through approximately 64 weeks post-dose.

A slow initial release of lenacapavir was observed, and therapeutic plasma concentrations were sustained for at least six months following a single 900 mg dose, administered as 3 x 1.0 mL injections. Similar results were observed following a 900 mg dose administered as 2 x 1.5 mL injections. Lenacapavir exposures increased in a generally dose-proportional manner from 300 mg to 900 mg, with maximum concentrations achieved 11 to 14 weeks post-dose and an apparent half-life of roughly 15 weeks.

Lenacapavir was generally well-tolerated; no serious or grade 3 or 4 adverse events (AEs) related to study drug or leading to study discontinuation occurred. The most common AEs were injection site induration (87 percent), pain (63 percent) and erythema (70 percent), all of which were mild. There were no clinically relevant laboratory abnormalities of grade 3 or higher.

Lenacapavir is an investigational compound and is not approved by the U.S. Food and Drug Administration or any other regulatory authority and the safety and efficacy are not yet known. There is no cure for HIV or AIDS.

About Gilead Sciences

Gilead Sciences, Inc. is a research-based biopharmaceutical company that discovers, develops and commercializes innovative medicines in areas of unmet medical need. The company strives to transform and simplify care for people with life-threatening illnesses around the world. Gilead has operations in more than 35 countries worldwide, with headquarters in Foster City, California.

For more than 30 years, Gilead has been a leading innovator in the field of HIV, driving advances in treatment, prevention, testing and linkage to care, and cure research. Today, it's estimated that more than 12 million people living with HIV globally receive antiretroviral therapy provided by Gilead or one of the company's manufacturing partners.

Gilead is committed to supporting the global health community to quickly and effectively respond to serious and life-threatening viral outbreaks worldwide. To that end, we are contributing our antiviral expertise and resources to help investigate potential treatments for patients with COVID-19.

Forward-Looking Statement

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 possibility of unfavorable results from ongoing and additional clinical trials involving lenacapavir, and the possibility that we are unable to complete one or more of such trials on the currently anticipated timelines or at all.

In addition, it is possible that Gilead may make a strategic decision to discontinue development of lenacapavir, and as a result, lenacapavir may never be successfully commercialized. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in Gilead's Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, as filed with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation to update any such forward-looking statements.

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