Tuesday, Jun 1, 1999

Immunex Corporation and Genentech, Inc. Join Forces To Develop TRAIL/Apo2L in Cancer

Seattle and South San Francisco, Calif. -- June 1, 1999 --

Immunex Corporation (NASDAQ: IMNX) and Genentech, Inc. (NYSE:GNE) announced today that the two companies agreed to jointly develop TRAIL/Apo2L, an entirely new approach to research in the fight against cancer. Pending FDA approval, the companies have also agreed to jointly commercialize the product.

"Combining our world class leadership in science and pharmaceutical development enhances our ability to more efficiently evaluate TRAIL/Apo2L and its potential to fight cancer," said Arthur D. Levinson, PhD, Genentech president and CEO, and Ed Fritzky, Immunex chairman and CEO, in a joint statement. "Should the science and clinical studies prove consistent with the preclinical findings that the molecule has already shown, our companies are poised to move to the next level of development with this new technology."

Immunex and Genentech have each conducted extensive preclinical testing of different forms of TRAIL/Apo2L. TRAIL/Apo2L, also known as TNF-related apoptosis-inducing ligand, appears in animal models to suppress tumor growth and causes remission of tumors, by a direct and specific mechanism known as apoptosis, or programmed cell death. TRAIL/Apo2L binds to at least four distinct receptors found on many tumor cells and signals these cells to destroy themselves through apoptosis. In preclinical research, TRAIL/Apo2L has been shown to cause a wide variety of tumor cells to undergo apoptosis while sparing normal cells. Preclinical studies have not identified significant toxicities from TRAIL/Apo2L administration.

The companies will form a joint steering committee and project team to select a single lead molecule for development, manage the development process, and allocate clinical, manufacturing and marketing responsibilities to each company. Immunex and Genentech each have filed patent applications covering TRAIL/Apo2L and its uses, and Immunex was awarded a patent covering the TRAIL gene in June 1998. Under the terms of the collaboration agreement, the companies will share all development and commercialization costs. The companies will co-promote TRAIL/Apo2L worldwide using the oncology sales forces of both companies. Profits from the worldwide sales of the product will be shared.

Immunex Corporation is a biopharmaceutical company dedicated to developing immune system science to protect human health. The company's products offer hope to patients with cancer, inflammatory and infectious diseases.

American Home Products owns a majority interest in Immunex. AHP is one of the world's largest research-based pharmaceutical and health care products companies. It is a leader in the discovery, development, manufacturing and marketing of prescription drugs and over-the-counter medications. It is also a leader in vaccines, biotechnology, agricultural products, and animal health care.

Genentech, Inc. is a leading biotechnology company that discovers, develops, manufactures and markets human pharmaceuticals for significant unmet medical needs. Twelve of the currently marketed biotechnology products stem from Genentech science. Genentech markets seven biotechnology products directly in the United States. The company has headquarters in South San Francisco, California, and is traded on the New York Stock Exchange and the Pacific Exchange under the symbol GNE.

# # #