Gilead Announces Start of Early Access Program for Investigational Anti-HIV Agent Tenofovir DF in United States and France

Programs to Begin in Germany, Italy, Spain and the United Kingdom upon Regulatory Clearance

Foster City, CA -- January 31, 2001

Gilead Sciences, Inc. (Nasdaq: GILD) today announced the initiation of a limited expanded access program to provide tenofovir disoproxil fumarate (tenofovir DF) to people with advanced human immunodeficiency virus (HIV) infection in the United States and multiple countries in the European Union. Regulatory review has been concluded and programs are open for registration in the United States and France. Early access programs will be initiated in Germany, Italy, Spain and the United Kingdom as regulatory approvals are obtained. Tenofovir DF is an investigational reverse transcriptase inhibitor, dosed as a single tablet once daily, currently being evaluated in combination with other agents in multinational Phase III clinical studies as a potential treatment for HIV infection.

Expanded access programs are part of an effort by the U.S. Food and Drug Administration (FDA), European regulatory agencies and the pharmaceutical industry to make investigational drugs available during the later stages of clinical development for the treatment of serious or life-threatening diseases.

"Patients with advanced HIV disease can rapidly run out of viable treatment options and often rely upon access to experimental therapies," said James Rooney, MD, Vice President of Clinical Research and leader of the worldwide Tenofovir DF Early Access Program at Gilead. "Initiating this limited program is our first step toward providing patients in greatest medical need with access to tenofovir DF.”

Program DesignThe U.S. program will make tenofovir DF available to patients at least 18 years of age with HIV infection who have had a CD4 count less than or equal to 100 cells/mm3 and an HIV RNA level of greater than or equal to 10,000 copies/mL by PCR within the past two months. Patients must also have failed treatment with at least two protease inhibitors (PIs) or one PI and one non-nucleoside analog reverse transcriptase inhibitor. Additionally, patients with a CD4 cell count between 100 cells/mm3 and 200 cells/mm3 and an AIDS-defining opportunistic infection within the last 90 days may also be eligible.

The U.S. program was designed with input from HIV patient advocates and representatives of HIV/AIDS community organizations. The viral load and CD4 cell count entry criteria for the U.S. program were established to insure that patients with the most advanced disease and in greatest need of a new antiretroviral therapy would have priority access during the initial stages of the program.

The French program will make tenofovir DF available to patients through an Authorisation Temporaire d’Utilisation de Cohorte. Design of early access programs in the European Union varies from country to country, according to specific regulatory guidelines.

Patients will receive tenofovir DF 300 mg dosed as a single tablet once daily. Gilead will advise physicians to include, in addition to tenofovir DF, at least one new antiretroviral agent that has not been previously administered to their patients.

Physician RegistrationFor more information regarding the tenofovir DF early access program or to request registration materials, physicians in the United States may call 1-800-GILEAD-5 and those within Europe may call 33-1-44-90-34-46. In the United States, Ingenix Pharmaceutical Services is the contract research organization that will administer the program, and Parexel will manage the program for the participating European countries.

Tenofovir DF Phase III ProgramTo evaluate the safety and efficacy of tenofovir DF 300 mg in combination with other antiretroviral agents for the treatment of HIV infection, Gilead initiated Study 907, a 552-patient Phase III clinical trial in November 1999 and completed enrollment in June 2000. Conducted in the United States, Europe and Australia, Study 907 is an ongoing intensification of therapy study of tenofovir DF in antiretroviral treatment-experienced patients.

Gilead initiated a second Phase III trial, Study 903, to evaluate tenofovir DF as a potential therapy for treatment-naive patients with HIV infection. This 48-week trial is designed to compare a treatment regimen of tenofovir DF, lamivudine (3TC) and efavirenz to a treatment regimen of stavudine (d4T), lamivudine and efavirenz in a blinded fashion in patients in the United States, Europe and South America who have not previously received antiretroviral treatment. Enrollment in Study 903 was completed in January 2001 at 601 patients.

Fast Track DesignationIn November 2000, the U.S. FDA granted Fast Track designation to tenofovir DF, recognizing the product’s potential to address an unmet medical need for a serious or life-threatening condition. Fast Track designation allows sponsors to initiate a rolling submission of a New Drug Application (NDA).

Gilead intends to submit the NDA to the U.S. FDA and the Marketing Authorisation Application to the European Medicines Evaluation Agency for tenofovir DF in mid-year 2001.

Gilead SciencesGilead Sciences, Inc., headquartered in Foster City, CA, is an independent biopharmaceutical company that seeks to provide accelerated solutions for patients and the people who care for them. Gilead discovers, develops, manufactures and commercializes proprietary therapeutics for challenging infectious diseases (viral, fungal and bacterial infections) and cancer. Gilead maintains research, development or manufacturing facilities in Foster City, CA; Boulder, CO; San Dimas, CA; Cambridge, UK and Dublin, Ireland and sales and marketing organizations 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. Such risks and uncertainties include: the risk that Gilead may not submit an NDA for tenofovir DF in mid-year 2001 or at all; and other risks related to regulatory approval of tenofovir DF. Factors that could cause Gilead to delay submission of an NDA for tenofovir DF include unexpected results of ongoing clinical trials and unexpected requests from the FDA for additional data regarding tenofovir DF . 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, 1999 and in Gilead’s Quarterly Reports on Form 10-Q, all of which are on file with the U.S. Securities and Exchange Commission.

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