Press Releases

April 19, 2002

Data From Study of Gilead's Adefovir Dipivoxil in Hepatitis B Patients With Lamivudine-Resistant Virus Presented At International Medical Meeting

Additional Virology Data Presented at 37th Meeting of European Association for the Study of the Liver

The data were discussed (#646) in an oral presentation at the 37th Annual Meeting of the European Association for the Study of the Liver (EASL) in Madrid, Spain by Marion Peters, MD, Principal Investigator and Chief of Hepatology Research, University of California, San Francisco Medical Center. This presentation is one of more than 20 abstracts on adefovir dipivoxil scheduled for presentation at EASL describing the anti-HBV activity, safety and resistance profile of adefovir dipivoxil in a variety of chronic hepatitis B patient populations. Preliminary data from Study 461 previously were announced in November 2001.

Adefovir dipivoxil belongs to a class of drugs called nucleotide analogues which are designed to work by blocking HBV DNA polymerase, an enzyme involved in the replication of the virus in the body. Gilead recently filed a New Drug Application (NDA) for adefovir dipivoxil with the U.S. Food and Drug Administration (FDA) and a Marketing Authorisation Application (MAA) with the European Medicines Evaluation Agency (EMEA). Gilead has requested a priority, or six month, review in the United States, and anticipates receiving an opinion from the Committee for Propriety Medicinal Products (CPMP) in Europe in the first half of 2003.

"These data indicate that adefovir dipivoxil, whether used alone or in combination with lamivudine, is active against HBV resistance mutations that develop in nearly one third of patients within one year of beginning treatment with lamivudine," said Dr. Peters. "The growing database from controlled clinical trials, including data presented earlier at this conference, suggest that treatment with adefovir dipivoxil significantly lowers serum HBV DNA and normalizes ALT levels. These results indicate that treatment with adefovir dipivoxil monotherapy may be a potential new therapeutic option for patients with chronic hepatitis B."

    About Study 461

Patients were randomized to receive either adefovir dipivoxil 10 mg (n=20), a combination of adefovir dipivoxil 10 mg with lamivudine 100 mg (n=20) or lamivudine 100 mg (n=19). After 16 weeks, patients in both the adefovir dipivoxil monotherapy and combination adefovir dipivoxil and lamivudine groups achieved similar, significant median reductions in serum HBV DNA levels from baseline (2.86 log10 copies/mL vs. 2.87 log10 copies/mL, p less than 0.0001). In comparison, serum HBV DNA levels remained the same (no decrease, or change of 0.00 log10 copies/mL) in patients treated with lamivudine 100 mg monotherapy (p less than 0.001 vs. both the adefovir dipivoxil monotherapy and adefovir dipivoxil plus lamivudine treatment arms). In addition, ALT levels normalized in 42 percent of patients receiving combination adefovir dipivoxil and lamivudine (p=0.008) and in 32 percent of patients treated with adefovir dipivoxil monotherapy (p=0.04) compared to six percent of patients receiving lamivudine monotherapy. Serum HBV DNA and ALT levels both are markers of disease severity. The most common adverse events reported were asthenia, abdominal pain and pharyngitis, and the nature, severity and frequency of adverse events were similar among all treatment arms. Additional data from this study will be analyzed following 48 weeks of treatment.

    Study 461 Resistance Data

"Gilead is dedicated to advancing therapeutics for life-threatening diseases worldwide by seeking solutions to complex treatment issues, such as resistance, faced by physicians and their patients," said John C. Martin, PhD, President and CEO, Gilead. "The breadth of adefovir dipivoxil data presented this week at EASL underscores the potential this drug may have to address the urgent, unmet medical needs of patients suffering from chronic hepatitis B."

    Chronic Hepatitis B

    Early Access Program Initiated

For more information regarding the adefovir dipivoxil early access program, or to request program registration materials, physicians may call 1-800-GILEAD-5 or 1-650-574-3000.

    Gilead Sciences

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 that could cause actual results to differ materially from those referred to in the forward-looking statements. Such risks and uncertainties include the risk that further data from ongoing and future clinical trials may not be as favorable as current data and other risks related to regulatory review and approval of adefovir dipivoxil in the United States and Europe. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in the Gilead Annual Report on Form 10-K for the year ended December 31, 2001 on file 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.

For more information on Gilead Sciences, please visit the company's web site at www.gilead.com or call the Gilead Corporate Communications Department at 1-800-GILEAD-5 or 1-650-574-3000.

CONTACT:          Gilead Sciences
                  Sheryl Meredith, 650/522-5505 (Investors)
                  Amy Flood, 650/522-5643 (Media)

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