Hoffmann-La Roche, Gilead Sciences Announce Collaboration to Co-promote Potential Hepatitis C Treatment in the U.S.

Nutley, NJ and Foster City, CA -- September 30, 1996

Hoffman-La Roche Inc. and Gilead Sciences, Inc. (NASDAQ:GILD) announced today that they have entered into a collaboration to co-promote Roche's Roferon®-A (Interferon alfa-2a, recombinant) for the potential treatment of chronic hepatitis C infection in the United States. Roche is currently marketing Roferon-A in the United States for the treatment of several types of cancer and is awaiting marketing clearance for the treatment of chronic hepatitis C infection. Gilead's co-promotion rights will be limited to the hepatitis C indication if and when approved.

If this indication is approved, as part of the agreement, Roche will pay Gilead a percentage of overall product net sales for the hepatitis C indication in each of the three years of the collaboration. In addition, Hoffmann-La Roche will provide Gilead a residual payment after completion of the co-promotion arrangement.

"Roche and Gilead together, with their joint antiviral 'know-how,' can work effectively together to address this important market," said Stephen G. Sudovar, Senior Vice President, Roche Laboratories.

Gilead Sciences will promote and market Roferon-A through its antiviral specialty sales force to hepatitis-treating physicians in the United States. Gilead's sales force currently markets VISTIDE^® (cidofovir injection) for the treatment of cytomegalovirus (CMV) retinitis, a sight-threatening viral infection in patients with AIDS.

"By working with Roche in the field of hepatitis C, we have the potential to build upon our antiviral presence in a therapeutic area of strategic importance to Gilead," said John C. Martin, Ph.D., President and Chief Executive Officer of Gilead Sciences.

In a separate release issued today, Gilead and Hoffmann-La Roche said they have also entered into a worldwide collaboration to develop and commercialize orally bioavailable compounds for the treatment and prevention of viral influenza.

Hepatitis C (HCV) Disease

Currently, it is estimated that 3.9 million Americans are infected with the hepatitis C virus, and as many as 180,000 new cases are diagnosed each year. The majority of patients with hepatitis C have no symptoms, making early clinical detection of HCV infection difficult. In 50% to 80% of people infected with acute hepatitis C, the infection becomes chronic (i.e., persists for longer than six months). Many patients with chronic hepatitis C develop cirrhosis of the liver or progressive liver failure and have a higher risk of developing hepatocellular carcinoma, a type of liver cancer.

Headquartered in Nutley, NJ, Hoffmann-La Roche Inc., is an affiliate of the multinational group of companies headed by Roche Holding Ltd of Basel, Switzerland. One of the world's leading research-intensive health care companies, Roche has discovered, developed and introduced numerous important prescription pharmaceuticals. The company is also a major provider of diagnostic products and services as well as vitamins, premixes and other products for human and animal nutrition and health. Recognized for excellence in both biotechnology and traditional chemistry, Roche is also widely known for its current efforts in the research, development and commercialization of polymerase chain reaction (PCR), a revolutionary advance in diagnostics and other fields, including biomedical research, forensics and environmental testing.

Gilead Sciences is a leader in the discovery and development of a new class of human therapeutics based on nucleotides, the building blocks of DNA and RNA. Gilead's first product, VISTIDE (cidofovir injection), was granted marketing clearance by the U.S. Food and Drug Administration in June 1996 for the first-line treatment of cytomegalovirus (CMV) retinitis in patients with AIDS. In addition, Gilead has products in human clinical testing for the potential treatment of human immunodeficiency virus (HIV), hepatitis B virus infection, herpes simplex virus and human papillomavirus-associated genital warts. The Company's research and development efforts encompass three interrelated programs: small molecule antivirals, cardiovascular therapeutics and genetic code blockers for cancer and other diseases. Gilead's expertise in each of these areas has also resulted in the discovery of non-nucleotide product candidates that expand the Company's technology platforms.