Gilead Announces Data Demonstrating that Single Dose of AmBisome® Safely and Effectively Treats Visceral Leishmaniasis in India

Study Accepted as Late-Breaker Presentation at 40th ICAAC

Toronto, Ontario -- September 17, 2000

Gilead Sciences, Inc. (Nasdaq: GILD) today announced promising results from a study conducted in India examining the use of a single dose of AmBisome® (amphotericin B) liposome for injection as a treatment for visceral leishmaniasis (VL). This open-label study explored the efficacy and safety of a single 7.5 mg/kg dose of AmBisome in 203 immunocompetent patients in India with confirmed VL. At 30 days post-treatment, 196 patients (97 percent) were parasite free, and at six months, 183 patients (90 percent) remained parasite free.

Results from this study were presented by Shyam Sundar, M.D., Professor of Medicine at the Institute of Medical Sciences, Banaras Hindu University, Varanasis, India, on Sunday, September 17, 2000 in a late-breaker oral presentation session at the 40th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Toronto, Canada.

“More than 60 percent of patients with VL in India do not respond to conventional treatment, indicating a need for an improved therapeutic for this disease,” said Dr. Sundar. “These data suggest that a single dose of AmBisome not only improves patient outcomes – resulting in a 90 percent long-term response rate with minimal side effects – it may also significantly reduce the duration of conventional therapy from one month or longer to only one day.”

An earlier study showed a 93 percent success rate in patients with resistant or relapsed VL when AmBisome was administered at a dose level of 7.5 mg/kg over a five-day period. This single-dose study, based on these earlier results, was conducted at four medical research centers in India. Side effects included fever (8 percent), vomiting (3.5 percent) and backache (1.5 percent). In the United States, AmBisome is indicated for the treatment of VL in immunocompetent patients at a recommended dose of 3 mg/kg/day on days 1-5, 14 and 21.

“This important research underscores the value of AmBisome and our ongoing commitment to extend the life-saving benefits of this drug to patients in need,” commented John C. Martin, Ph.D., President and Chief Executive Officer, Gilead Sciences.

Visceral leishmaniasis, also known as kala-azar or black fever, is caused by the parasite Leishmania and is spread through the bite of a female sandfly. It is characterized by fever, substantial weight loss, swelling of the spleen and liver, and anemia. The infection is most prevalent in India, Brazil and the Sudan.

About AmBisome
AmBisome is a unilamellar (single-layer) liposomal formulation of amphotericin B. Available in 42 countries worldwide, AmBisome is the only true liposomal formulation of amphotericin B, the standard of care for systemic antifungal therapy. AmBisome labels include indications for empirical therapy for presumed fungal infection in febrile, neutropenic patients; Aspergillus species, Candida species and/or Cryptococcus species infections refractory (non-responsive) to conventional amphotericin B; and the treatment of VL. Additionally, AmBisome is recommended for the treatment of patients where renal impairment or nacceptable toxicity suggests that conventional amphotericin B should not be used or should be discontinued. Product labeling for AmBisome varies in each of the countries in which it is marketed.

In July, the U.S. Food and Drug Administration approved AmBisome as a treatment for cryptococcal meningitis in HIV-infected patients. This approval followed a label expansion earlier in the year to include head-to-head data demonstrating AmBisome’s superior safety profile versus Abelcet® (amphotericin B lipid complex).

AmBisome has a demonstrated superior safety profile compared to conventional amphotericin B for the empirical treatment of febrile, neutropenic patients. In clinical trials, nephrotoxicity and infusion-related reactions were observed. Side effects associated with the use of AmBisome include, but are not limited to, chills, diarrhea, nausea and vomiting. For full prescribing information for AmBisome, please call 1-800-GILEAD-5 (1-800-445-3235) or 1-650-574-3000 from outside the United States.

About Gilead
Gilead Sciences, 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. The company 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. For more information about Gilead, visit the company's Web site at www.gilead.com.

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, 1999 on file with the U.S. Securities and Exchange Commission.