FDA Grants Fast Track Designation for Amgen's AMG 531 and AMG 706 Experimental Therapies to Potentially Treat Life-Threatening Conditions.

THOUSAND OAKS, Calif. -- Amgen Inc. (Nasdaq:AMGN), the world's largest biotechnology company, today announced that the U.S. Food and Drug Administration (FDA) has granted fast track designation for two of the company's experimental therapies, AMG 531 and AMG 706. AMG 531 received orphan drug designation in 2003.

"AMG 531 is Amgen's first peptibody and represents a new approach to potentially treat immune thrombocytopenic purpura (ITP), an autoimmune bleeding disorder. AMG 706, Amgen's first investigational oral cancer therapy, may hold promise for various tumor types and is currently in Phase 2 trials for the treatment of imatinib-resistant gastrointestinal stromal tumors (GIST), a fatal cancer," said Beth Seidenberg, M.D., chief medical officer and senior vice president of global development at Amgen. "Fast track designation represents an important step for both of these molecules and will help to streamline development."

Under the FDA Modernization Act of 1997, fast track designation allows the FDA to accept, on a rolling basis, portions of a marketing application for review prior to the completion of the final registrational package. Fast track designation may potentially expedite the review of a drug that is intended for the treatment of a serious life-threatening condition and demonstrates the potential to address an unmet medical need for such a condition. The FDA orphan drug designation provides marketing exclusivity incentives to companies that develop drugs for diseases affecting less than 200,000 people in the United States.

The Use of AMG 531 in Immune Thrombocytopenia Purpura (ITP)

About Immune Thrombocytopenia Purpura (ITP)

Immune (idiopathic) thrombocytopenia purpura (ITP) is an autoimmune bleeding disorder characterized by low levels of platelets in the blood. ITP affects approximately 70,000 people in the U.S. Current treatment of ITP involves reducing platelet destruction with drugs (e.g., corticosteroids) that alter or suppress the immune system or with surgical removal of the spleen (splenectomy), where the antibody-tagged platelets are destroyed. Corticosteroids are associated with side effects such as weight gain, rash and exacerbation of diabetes and osteoporosis. Splenectomy and other therapies used to treat ITP that suppress or modulate the immune system can increase a patient's risk of infection. Since approximately 50 percent of patients do not respond to drug therapy and 40 percent of patients do not respond to splenectomy, new therapies for ITP are needed.

About AMG 531

As an investigational platelet growth factor, AMG 531 appears to directly stimulate platelet production and may offer physicians a way to shift the treatment focus from preventing platelet destruction to boosting platelet production in patients with ITP. AMG 531 is an engineered protein therapeutic developed by Amgen called a peptibody that provides targeted action -- in this case, on the thrombopoietin (TPO) receptor. Like TPO, AMG 531 binds to the TPO receptor and stimulates precursor or "parent" cells of platelets, called megakaryocytes, to mature into platelets.

In Phase 1 and 2 clinical studies recently reported at the 46th Annual American Society of Hematology (ASH) meeting, AMG 531 appeared to enhance platelet production in patients diagnosed with ITP. AMG 531 has been generally well tolerated. The most frequently reported adverse events were bruising, nosebleeds, headache and mouth blisters.

The Use of AMG 706 in Imatinib-Resistant Gastrointestinal Stromal Tumors (GIST)

About Gastrointestinal Stromal Tumors (GIST)

Gastrointestinal stromal tumors (GISTs) belong to a group of cancers called soft tissue sarcomas. Sarcomas are a rare type of cancer that can occur in connective tissues, bones, muscles, fat, nerves, blood vessels and cartilage. GISTs start in the wall of the stomach, small and large intestine and affect approximately 5,000 to 10,000 Americans annually. Since GIST are resistant to traditional treatments such as chemotherapy and radiation, surgery is considered the best way to initially treat GIST. However, many tumors cannot be surgically removed because they are too large or have already spread to other parts of the body before diagnosis. Since its approval in 2002, imatinib has been the mainstay of therapy for advanced or metastatic GIST. However, no approved therapies exist for GIST patients that no longer respond to imatinib.

About AMG 706

AMG 706 is an oral multi-kinase inhibitor (MKI) that works by selectively targeting all known vascular endothelial growth factors (VEGF), platelet derived growth factor (PDGF), Kit and Ret receptors. Through the combined action of Kit and PDGF receptor inhibition, coupled with potent VEGF receptor inhibition, AMG 706 potentially may provide more than one mechanism of action in various cancers. Activating mutations of Kit or PDGF receptors are critical to the pathogenesis of more than 90 percent of GIST.

Early clinical data show signs of tumor regression with promising preliminary safety data that may potentially allow for combination therapy. AMG 706 is being evaluated as both a monotherapy and in combination with other agents for the treatment of various cancers, including imatinib-resistant GIST, non-small cell lung cancer and colorectal cancer.

Patients and physicians can access www.amgentrials.com for more information about ongoing AMG 531 and AMG 706 clinical trials.

About Amgen

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

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