Press Releases

February 25, 2002

Viread Demonstrates Anti-HIV Potency Similar to the Protease Inhibitor Ritonavir in Short-Term Study of Treatment-Naive Patients

Results from Aaron Diamond AIDS Research Center Study Presented at 9th Conference on Retroviruses and Opportunistic Infections

These data were described in an oral presentation (#3) given by Michael Louie, MD, Aaron Diamond AIDS Research Center, The Rockefeller University, New York, NY, at the 9th Conference on Retroviruses and Opportunistic Infections in Seattle, Washington.

"Studies of early changes in plasma HIV-1 RNA levels may provide a reliable comparative analysis of the potency of antiretroviral agents. The results of this study suggest that tenofovir DF has potency comparable to that of a protease inhibitor when used as monotherapy in patients infected with HIV who have not been previously treated with antiretrovirals," commented Martin Markowitz, MD, Clinical Director and Staff Investigator, Aaron Diamond AIDS Research Center and lead investigator for the study.

    Study 917 Design and Results

Study 917 was a 21-day open-label study designed to assess the anti-HIV activity of Viread as monotherapy in antiretroviral-naive patients infected with HIV. In this study, 10 chronically HIV-infected patients (nine males, one female) with an average age of 34 years were hospitalized for initiation of Viread 300 mg once daily as monotherapy. Patients' HIV RNA levels were monitored every six hours for the first 72 hours. After discharge, patients were seen daily until day 10 and then on days 12, 14 and 21.

At study enrollment, patients had a mean HIV RNA level of 4.3 log10 copies/mL (range: 3.7 to 5.1). After three weeks, patients treated with Viread monotherapy experienced a mean reduction in HIV RNA of 1.5 log10 copies/mL (range: 0.6 to 2.7). The mean initial decay rate for Viread was -0.39 per day (range: -0.24 to -0.59). Previously determined mean initial decay rates were -0.99 per day for a highly active antiretroviral therapy (HAART) regimen containing Kaletra(R) (lopinavir/ritonavir), Sustiva(R) (efavirenz), Viread and Epivir(R) (lamivudine) and -0.34 per day for ritonavir monotherapy. By comparison to these previously determined rates, data from this study indicate that the relative efficacy of Viread is 15 percent higher than ritonavir monotherapy and is 39 percent that of the potent four-drug HAART regimen, as detailed above.

"Results from this Aaron Diamond study confirm earlier data demonstrating that Viread is a potent inhibitor of viral replication in treatment-naive patients," said John C. Martin, PhD, President and CEO, Gilead Sciences. "Together with a safety profile comparable to placebo and single-tablet, once-daily dosing, these data are further evidence that Viread may provide physicians and patients with a new antiretroviral option applicable for any regimen."

    About Viread

In the United States, Viread is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. This indication is based on analyses of plasma HIV-1 RNA levels and CD4 cell counts in a controlled study of Viread of 24 weeks duration and in a controlled, dose ranging study of Viread of 48 weeks duration. Both studies were conducted in treatment-experienced adults with evidence of HIV-1 viral replication despite ongoing antiretroviral therapy. Studies in antiretroviral-naive patients are ongoing; consequently, the risk-benefit ratio for this population has yet to be determined.

    HIV Resistance Profile

    Safety Profile

The most common adverse events in patients receiving Viread were mild to moderate gastrointestinal events, such as nausea, diarrhea, vomiting and flatulence. Laboratory abnormalities observed in clinical studies occurred with similar frequency in the Viread and placebo-treated groups. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues alone or in combination with other antiretrovirals.

    Ongoing Clinical Studies

    About HIV/AIDS

    About Gilead

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, including the risk that the safety and efficacy data observed in the studies described in this press release may not continue to be observed in broader patient groups or through longer periods of treatment. 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, 2000 and in Gilead's Quarterly Reports on Form 10-Q, all of which are 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.

Note to Editors: Viread is a trademark of Gilead Sciences, Inc.

For full prescribing information on Viread, please call 1-800-GILEAD-5 (1-800-445-3235) or visit www.viread.com.

CONTACT:          Gilead Sciences
                  Susan Hubbard, 650/522-5715 (Investors)
                  Amy Flood, 650/522-5643 (Media)

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