AMGEN AND PRAECIS FORM COLLABORATION TO DEVELOP AND COMMERCIALIZE PHASE 3 DRUG FOR PROSTATE CANCER AND OTHER DISORDERS.

THOUSAND OAKS, Calif.--(BUSINESS WIRE)--March 10, 1999--Amgen (NASDAQ:AMGN) today announced that it has entered into a collaboration with PRAECIS PHARMACEUTICALS INCORPORATED under which the companies will develop and Amgen will commercialize abarelix in the United States, Canada, Australia, Asia and several secondary markets.

This collaboration will result in approximately $100 million of expense in 1999 for Amgen. Total product sales are now expected to grow in the mid to high teens in 1999. As a result, despite the increase in expense from this collaboration, Amgen is comfortable with the current range of analysts' estimates of $1.80 - $1.85.

Abarelix is currently in phase III trials in patients with hormonally-responsive prostate cancer. A second formulation is in a phase I/II clinical trial in patients with endometriosis, a painful gynecologic condition resulting from abnormal growth of the lining of the uterus.

Abarelix, known as a GnRH antagonist, inhibits the action of gonadotropin releasing hormone (GnRH, also called LHRH) on the pituitary gland, thereby reducing the production of testosterone in men and estrogen in women. The elimination of testosterone or estrogen through the use of pharmaceuticals, a practice known as hormonal therapy, confers a therapeutic benefit to patients with a number of diseases and medical conditions including prostate cancer and endometriosis. In phase II studies, abarelix was shown to reduce testosterone to very low levels in the great majority of men within the first week, compared with no patients treated with the currently available drugs, known as hormonal superagonists.

Abarelix was developed by Cambridge, Mass. based PRAECIS, a privately-held company engaged in the development of peptide-based therapeutics for the treatment of human diseases.

"Abarelix is the first of a new class of drugs that more rapidly reduces the levels of testosterone and estrogen and represents a potential advance for patients because it acts more quickly and may eliminate some of the adverse effects of existing drugs," said Marc Garnick, M.D., chief medical officer of PRAECIS and a noted authority on prostate cancer.

"Abarelix represents an exciting opportunity for Amgen to leverage our success with NEUPOGEN(R) in the oncology area and to establish a strong presence in urology and gynecology," said Gordon Binder, chairman and chief executive officer. "We continue to seek outside opportunities to supplement our internal research and development programs."

"This collaboration with Amgen provides PRAECIS with an outstanding partner to complete the commercialization phase of its first product," said Malcolm L. Gefter, chairman and chief executive officer of PRAECIS.

Currently available hormonal superagonists cause an initial surge in testosterone levels that can stimulate cell growth in prostate cancer, a complication known as a clinical flare. Superagonists do cause testosterone levels to fall but only after a delay of three to four weeks. This delay in testosterone suppression and the potential for a clinical flare leaves patients at increased risk from their cancer.

Abarelix has been shown in clinical trials to halt the production of hormones quickly and without the surge and resulting clinical flare associated with hormonal superagonists. In some patients with advanced hormonally responsive prostate cancer, the testosterone surge associated with superagonists may result in worsening of the cancer.

Prostate cancer is one of the most common malignant tumors in men, with an estimated 179,300 new cases and 37,000 deaths projected in 1999. A substantial proportion of cases are diagnosed at an advanced stage, and in about 80 percent of men, the growth of the disease is stimulated by testosterone. Many patients with non-localized cancer are treated with long-term hormonal therapy to achieve androgen ablation. For men with localized cancer, hormonal therapy is also increasingly being used as an adjunct to other therapies such as radiation treatment.

This news release contains forward-looking statements that involve significant risks and uncertainties, including those discussed below and more fully described in the Securities and Exchange Commission reports filed by Amgen, including our most recent Forms 10-Q and 10-K. Amgen conducts research in the biotechnology/pharmaceutical field where it is difficult to move from concept to product; consequently, there can be no guarantee that any particular product candidate will be successful and become a commercial product. Consummation of this transaction is subject to compliance with Hart-Scott-Rodino requirements and other customary conditions.

Furthermore, our research, testing, pricing, marketing and other operations are subject to extensive regulation by domestic and foreign government regulatory authorities. In addition, sales of our products are affected by reimbursement policies imposed by third party payors, including governments, private insurance plans and managed care providers. These government regulations and reimbursement policies may affect the development, usage and pricing of our products. In addition, while we routinely obtain patents for our products and technology, the protection offered by our patents and patent applications may be challenged, invalidated or circumvented by our competitors.

Amgen is a global biotechnology company that discovers, develops, manufactures and markets cost-effective human therapeutics based on advances in cellular and molecular biology.

PRAECIS PHARMACEUTICALS INCORPORATED was founded in 1993 to rapidly develop and commercialize drugs that target significant clinical needs. PRAECIS employs a series of integrated technologies, including gene-based and chemistry-based combinatorial chemistry and drug delivery methodology.

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