Press Releases

March 11, 2003

Gilead Sciences' Hepatitis B Drug Hepsera Approved for Marketing in European Union

More than 400 million people worldwide have chronic hepatitis B, which is caused by infection with the hepatitis B virus (HBV), and between one quarter and one third of these individuals are expected to develop progressive liver disease, such as cirrhosis and liver cancer. Approximately nine million people are chronically infected with HBV in Europe. An estimated one million people die annually from complications of chronic hepatitis B making it one of the leading causes of death worldwide.

"To date, the limitations of available hepatitis B drugs, such as poor tolerability and rapid development of viral resistance, have made them unsuitable or ineffective for many patients," said Professor Stephanos Hadziyannis, MD, Department of Medicine, Henry Dunant Hospital, Athens, Greece. "In clinical studies, Hepsera significantly reduced disease progression in a wide range of patients. Broad efficacy, good tolerability and a low risk of resistance make Hepsera an important advancement in the treatment of chronic hepatitis B."

Hepsera is administered as a once-daily 10 mg tablet and works by blocking HBV DNA polymerase, an enzyme involved in the replication of the virus in the body. The U.S. Food and Drug Administration (FDA) cleared Hepsera for marketing in the United States on September 20, 2002. Regulatory filings for the drug also have been completed in Australia, Switzerland, Turkey and Canada, and additional regulatory filings are planned in other countries in the coming months.

"The approval of Hepsera by the European Commission comes less than a year after Gilead filed its Marketing Authorisation Application with the European authorities, demonstrating the important unmet medical need Hepsera will address for physicians and their patients with chronic hepatitis B," said John C. Martin, PhD, President and CEO, Gilead Sciences.

Access to Hepsera

In July 2002, Gilead initiated an early access program to provide Hepsera to chronic hepatitis B patients with lamivudine-resistant virus. To date, over 1,600 patients have enrolled in Hepsera early access programs in France, Italy, Greece, Spain, Portugal, Germany, the United Kingdom, Canada and Australia. The Hepsera early access programs will continue until the drug is commercially available to patients in these countries. For more information regarding the Early Access Program for Hepsera in Europe, please call +33 1 44 90 34 75.

Clinical Studies of Hepsera

Two placebo-controlled studies and a number of additional studies have evaluated Hepsera in a wide range of patients. The placebo-controlled studies included patients with compensated liver function and either "e" antigen-positive (HBeAg-positive) or "e" antigen-negative (HBeAg-negative, or precore mutant) chronic hepatitis B. The 48-week results from these two pivotal studies were published in the February 27 edition of the New England Journal of Medicine. Precore mutant hepatitis B infects up to approximately 50 percent of chronic hepatitis B carriers worldwide, and is most prevalent in countries of the Mediterranean and Southeast Asia, where between 30 and 80 percent of chronic hepatitis B patients are estimated to be infected with this strain. Hepsera also has been studied in patients who were treated with and developed resistance to lamivudine, including patients wait-listed for liver transplantation, post-liver transplantation patients and patients co-infected with HIV.

In clinical studies, Hepsera reversed or slowed the progression of liver damage, reduced HBV DNA levels in the blood and increased rates of seroconversion and normalization of ALT levels (an indicator of liver function) significantly more effectively than placebo in treatment-naive patients and in patients with prior interferon treatment.

Tolerability and Safety Profile

The adverse reactions considered at least possibly related to treatment in the first 48 weeks of therapy with Hepsera were asthenia (weakness), headache, abdominal pain, nausea, flatulence, diarrhea and dyspepsia. With extended treatment, mild to moderate, reversible, increases in serum creatinine were observed infrequently in patients with chronic hepatitis B and compensated liver disease treated with Hepsera for a median of 49 weeks and a maximum of 109 weeks. Changes in serum creatinine were observed very commonly in patients with pre- and post-liver transplantation with lamivudine-resistant hepatitis B and multiple risk factors for changes in renal function who were treated with Hepsera for up to 129 weeks, with a median time on treatment of 19 and 56 weeks, respectively. Clinical and laboratory evidence of exacerbations of hepatitis has been observed after discontinuation of treatment with Hepsera. Special warnings and precautions for use are included in the Summary of Product Characteristics regarding monitoring of renal function and post-treatment exacerbations of hepatitis, use in patients with underlying renal impairment or patients co-infected with HIV, and occurrence of nucleoside analogue-associated lactic acidosis and severe hepatomegaly with steatosis.

Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes therapeutics to advance the care of patients suffering from life-threatening diseases worldwide. The company has six marketed products and focuses its research and clinical programs on anti-infectives. Headquartered in Foster City, CA, Gilead has operations in the United States, Europe and Australia.

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. 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 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.

Hepsera is a trademark of Gilead Sciences, Inc.

For more information on Gilead Sciences, please visit the company's web site at www.gilead.com or call the Gilead Public Affairs Department at 1-800-GILEAD-5 (1-800-445-3235) or 1-650-574-3000.

CONTACT:          Gilead Sciences
                  Susan Hubbard, 650/522-5715 (Investors)
                  Erin Edgley, 650/522-5635 (Media)

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