Press Release Details

THOUSAND OAKS, Calif. -- January 23, 2003 – Amgen (Nasdaq: AMGN), announced today that rHu-KGF decreased the duration and incidence of severe oral mucositis in a phase 3 study of patients undergoing bone marrow transplantation treatment for hematologic malignancies such as lymphoma, multiple myeloma, and leukemia.

Natural keratinocyte growth factor stimulates the growth and development of epithelial cells, including the cells that line the gastrointestinal tract. Amgen is studying a recombinant human keratinocyte growth factor (rHu-KGF) to protect epithelial cells from injury caused by anti-tumor treatments such as radiation and chemotherapy. Mucositis is a painful and debilitating condition in which patients experience severe mouth ulcerations that can make swallowing difficult or Preliminary results from the Phase 3 randomized, double blind trial were positive on all end-points showing highly significant decrease in both the duration and incidence of severe mucositis. The trial also showed that KGF was well Roger Perlmutter, Amgen's executive vice president of research and development, said: “There is no currently approved therapy to treat oral mucositis, a sometimes devastating complication of cancer chemotherapy. We are looking forward to discussing our phase 3 results that address this critical unmet medical need with regulatory agencies in the near future.” Amgen will now investigate the efficacy and safety of KGF in other patient populations who suffer from high rates of mucositis associated with their antitumor treatments.

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 Form 10-Q. Amgen conducts research in the biotechnology/pharmaceutical field where movement from concept to product is uncertain; consequently, there can be no guarantee that any particular product candidate will be successful and become a commercial product.

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.

Because forward-looking statements involve risks and uncertainties, actual results may differ materially from current results expected by Amgen. Amgen is providing this information as of January 23, 2003 and expressly disclaims any duty to update information contained in this press release.

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

CONTACT: Amgen, Thousand Oaks
Jeff Richardson, 805/447-3227 (media)
Cary Rosansky, 805/447-4634 (investors)