Press Releases

April 18, 2002

92-Week Data From Clinical Study of Gilead's Adefovir Dipivoxil in Patients Co-Infected With HIV and Lamivudine-Resistant HBV Presented At International Medical Meeting

Data Discussed at 37th Meeting of European Association for the Study of the Liver

The data are scheduled for presentation (#643) at the 37th Annual Meeting of the European Association for the Study of the Liver (EASL) in Madrid, Spain by Yves Benhamou, MD, Service d'Hepato-Gastroenterologie, Groupe Hospitalier Pitie-Salpetriere, Paris, France. This presentation is one of more than 20 abstracts characterizing data from studies of adefovir dipivoxil slated for presentation at EASL.

"These data show that adefovir dipivoxil is active against the most common HBV resistance mutation -- YMDD -- that develops within four years in nearly 90 percent of chronic hepatitis B patients co-infected with HIV who have been treated with lamivudine," said Dr. Benhamou. "Treatment with adefovir dipivoxil results in a continued and progressive reduction of serum HBV DNA through nearly two years of treatment. This is especially important because patients co-infected with both HIV and lamivudine-resistant HBV are often more difficult to treat than patients infected with either virus by itself."

    About Study 460i

After 92 weeks of treatment, adefovir dipivoxil was associated with a significant decrease in mean serum HBV DNA levels of 5.13 log10 copies/mL (n=31; p less than 0.001). Levels of serum HBV DNA steadily declined over the course of treatment, from 2.90 log10 copies/mL at week 12, 3.40 log10 copies/mL at week 24, 4.01 log10 copies/mL at week 48, 4.74 log10 copies/mL at week 72 to 5.13 log10 copies/mL at week 92. These levels were undetectable (less than 1000 copies/mL by Roche PCR) in 29 percent of patients.

Over the course of the study, no resistance mutations developed that were associated with decreased susceptibility to adefovir dipivoxil or rebound in serum HBV DNA levels. In addition, nine percent of chronic hepatitis B patients who were hepatitis B "e" antigen (used to denote hepatitis B viral replication) positive at baseline achieved seroconversion by week 92. Overall, adefovir dipivoxil 10 mg was well tolerated in this study. During the course of the trial, four patients discontinued for reasons thought to be unrelated to adefovir dipivoxil, as judged by the investigator.

    Study 460i Virology Analyses

    About Adefovir Dipivoxil

    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 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 650/574-3000.

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

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