Gilead Provides Update on Clinical Studies Evaluating GS-1720 and/or GS-4182 for the Treatment of HIV-1 Infection

Foster City, Calif., June 10, 2025 – The U.S. Food and Drug Administration has placed a clinical hold on Gilead’s HIV treatment trials of GS-1720 (an investigational integrase strand transfer inhibitor) and/or GS-4182 (an investigational capsid inhibitor). The clinical hold is due to the identification of a safety signal of decreases in CD4+T-cell (CD4) and absolute lymphocyte counts in a subset of participants receiving the combination of GS-1720 and GS-4182.

Clinical trial investigators involved in the trials have been informed of these actions. GS-1720 and GS-4182 are investigational agents and have not been approved anywhere globally. We intend to investigate and pursue the potential of both agents and are committed to working with regulatory authorities to resolve the issues underlying the clinical hold.

Gilead has multiple other long-acting oral and injectable investigational HIV treatment combinations under evaluation in clinical and preclinical studies, including combinations with weekly, monthly, quarterly, and twice-yearly dosing. This hold does not impact these combinations or their respective clinical or pre-clinical development programs.

The safety of individuals taking Gilead medicines is our foremost priority and we remain focused on pursuing advances to improve outcomes and expand options for people living with HIV.

The following studies have been placed on clinical hold:

Three additional Phase 1 trials of either agent and/or their combinations are also on hold.

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, COVID-19, cancer and inflammation. Gilead operates in more than 35 countries worldwide, with headquarters in Foster City, Calif.

Forward-Looking Statement

This company statement 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 resolve the issues cited by the FDA in the clinical hold to the satisfaction of the FDA and the risk the FDA may not remove the clinical hold, in whole or in part, in timely manner or at all; Gilead’s ability to initiate, progress and complete clinical trials involving GS-1720 and/or GS-4182 in the anticipated timelines or at all, and the possibility of unfavorable results from ongoing and additional clinical trials, including those involving GS-1720 and/or GS-4182; uncertainties relating to regulatory applications and related filing and approval timelines; the possibility that Gilead may make a strategic decision to discontinue development of GS-1720 and/or GS-4182 and, as a result, GS-1720 and/or GS-4812 may never be successfully commercialized; 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, 2025, 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 involve risks and uncertainties, 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.

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