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Enbrel Rapidly and Significantly Improved Back Pain, Mobility and Physical Function in Patients with Ankylosing Spondylitis

FOR IMMEDIATE RELEASE

THOUSAND OAKS, Calif., and COLLEGEVILLE, Pa., June 19, 2003 - Amgen (NASDAQ: AMGN) and Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE), today announced that patients in a phase 3 clinical study assessing the efficacy and tolerability of ENBREL. (etanercept) in the treatment of active ankylosing spondylitis experienced significant and rapid reduction in back pain and morning stiffness, and improvement in spinal mobility and physical function. The data are part of a presentation at the annual meeting of European League Against Rheumatism being held this week in Lisbon, Portugal.

"A significant number of patients treated with ENBREL in this study saw a marked improvement in as early as two weeks after initiation of treatment. Patients reached maximum relief within the first two months of the study and experienced sustained results for the remainder of the six-month study," said Dr. John Davis, assistant professor of medicine at the University of California-San Francisco and associate director of the Department of Medicine Clinical Trials Center. "I am excited about these encouraging results with ENBREL, especially since it is the first treatment to show improvement in AS patients' range of spinal motion in a phase 3 study."

The multi-center, double-blind, placebo-controlled study randomized 277 patients to receive either ENBREL (25 mg twice weekly; n=138) or placebo (n=139) over a 6-month period. The primary endpoint of the pivotal Phase 3 study was the percentage of patients at 12 weeks and 24 weeks achieving a 20 percent improvement in the Assessment in Ankylosing Spondylitis Response Criteria (ASAS 20), a composite measure that includes back pain, inflammation and physical function.

At week 12, 60 percent of patients treated with ENBREL achieved the ASAS 20 compared with 27 percent of patients in the placebo group. At 24 weeks, 58 percent of patients treated with ENBREL achieved the ASAS 20 compared with 23 percent of the placebo patients.

"When we measured spinal mobility and back pain, the most debilitating aspects of AS, we found that patients treated with ENBREL experienced significantly greater improvement in mobility than patients receiving placebo and a 50 percent reduction in spinal pain," said Dr. Davis. "ENBREL also had a positive impact on many patients' ability to accomplish everyday tasks, such as being able to more easily put on socks or look over their shoulders without turning their bodies."

Adverse events were similar to those reported in previous clinical trials of ENBREL, with injection site reactions occurring more frequently than in the placebo group.

The most frequent adverse events in placebo-controlled RA clinical trials (n=349) were injection site reactions (ISR) (37%), infections (35%), and headache (17%). Only the rate of ISR was higher than that of placebo. The most frequent adverse events in a methotrexate-controlled trial (n=415) were infections (64%), ISR (34%), and headache (24%). Only the rate of ISR was higher than that of methotrexate.

Currently there are few treatments approved by the U.S. Food and Drug Administration (FDA), other than non-steroidal anti-inflammatory agents and steroids, to treat this chronic disease. A supplemental biologics license application (sBLA) is under review by the FDA for the use of ENBREL in treating ankylosing spondylitis. If approved for use in AS, ENBREL will be the first TNF receptor therapy available to treat the disease.

ABOUT ANKYLOSING SPONDYLITIS

Ankylosing spondylitis is a painful, chronic and progressive inflammatory disease affecting the spine and the joints and ligaments that normally allow a person's back to move and flex. Over time, new bone can develop and replace the elastic tissue of ligaments or tendons. Eventually, a patient's vertebrae can fuse together, causing complete loss of motion and a stooped-over posture. Ankylosing spondylitis affects about 350,000 people in the United States.

The disease frequently begins in the lower back or pelvis and, with time, may progress into the upper spine, chest and neck. Ankylosing spondylitis may also involve other joints, such as the hips, shoulders, knees, and ankles.

Ankylosing spondylitis belongs to a family of spine-related inflammatory diseases (spondyloarthropathies).

ABOUT ENBREL

ENBREL is the only fully human anti-TNF receptor approved for use to reduce the signs and symptoms and inhibit the progression of structural damage in patients with moderately to severely active RA, and to reduce the signs and symptoms of active arthritis in patients with psoriatic arthritis. ENBREL is the only biologic therapy approved to treat newly diagnosed RA patients, and can be used alone. It is also approved to reduce the signs and symptoms of moderately to severely active polyarticular-course juvenile rheumatoid arthritis (JRA) in patients who have had an inadequate response to disease-modifying medicines.

Physicians have become familiar with the benefits and proven long-term tolerability profile of ENBREL. It has been used to treat over 180,000 patients worldwide across all indications since becoming commercially available five years ago.

ENBREL acts by binding TNF, one of the dominant inflammatory cytokines or regulatory proteins that play an important role in both normal immune function and the cascade of reactions that causes the inflammatory process of psoriatic arthritis and RA. The binding of ENBREL to TNF renders the bound TNF biologically inactive, resulting in significant reduction in inflammatory activity.

Individual results may vary. In medical studies, ENBREL worked for about two out of three adults with RA, three of four children with JRA, and about 50 percent of patients with psoriatic arthritis.

Since the product was first introduced, the following have been reported in patients using ENBREL:

Serious Infections

- Many occurred in people prone to infection, such as those with advanced or poorly controlled diabetes

- Some serious infections were fatal

- Rare cases of tuberculosis

What to do/Not do

- Do not start ENBREL if you have an infection or are allergic to ENBREL or its components

- Tell your doctor if you are prone to infection

- Stop ENBREL if a serious infection occurs

- Contact your doctor if you have questions about ENBREL or develop an infectionSerious nervous system disorders such as multiple sclerosis, seizures, or inflammation of the nerves of the eyes.

- Tell your doctor if you have ever had any of these disorders or if you develop them after starting ENBREL.

• Rare reports of serious blood disorders (some fatal)

- Contact your doctor immediately if you develop symptoms such as persistent fever, bruising, bleeding, or paleness

• The incidence of cancer has not increased with extended exposure to ENBREL and is similar to the expected rate.

• ENBREL can also cause injection site reactions.

• In a medical study of patients with JRA, infections, headaches, abdominal pain, vomiting, and nausea occurred more frequently than in adults.

- The kinds of infections reported were generally mild and similar to those usually seen in children

- Other serious adverse reactions were reported rarely, including serious infections (2%) and depression/personality disorder (1%)

Amgen and Wyeth Pharmaceuticals, a division of Wyeth, market ENBREL in North America. Wyeth markets ENBREL outside of North America. Immunex Corporation, a wholly owned subsidiary of Amgen, manufactures ENBREL. Additional information about ENBREL, including full Prescribing Information, can be found on the Web site sponsored by the companies at www.enbrel.com or by calling toll free 888-4ENBREL (888-436-2735).

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

Wyeth Pharmaceuticals, a division of Wyeth, has leading products in the areas of women's health care, cardiovascular disease, central nervous system, inflammation, hemophilia, oncology and vaccines. Wyeth (NYSE: WYE) is one of the world's largest research-driven pharmaceutical and health care products companies. It is a leader in the discovery, development, manufacturing and marketing of pharmaceuticals, vaccines, biotechnology products and nonprescription medicines that improve the quality of life for people worldwide. The Company's major divisions include Wyeth Pharmaceuticals, Wyeth Consumer Healthcare and Fort Dodge Animal Health.

This news release contains forward-looking statements that involve significant risks and uncertainties, including those discussed below and others that can be found in Amgen's Form 10-K for the year ended December 31, 2002, and in Amgen's periodic reports on Form 10-Q and Form 8-K. Amgen is providing this information as of the date of this news release and does not undertake any obligation to update any forward-looking statements contained in this document as a result of new information, future events or otherwise.

No forward-looking statement can be guaranteed and actual results may differ materially from those we project. Amgen's results may be affected by its ability to successfully market both new and existing products domestically and internationally, sales growth of recently launched products, difficulties or delays in manufacturing its products, and regulatory developments (domestic or foreign) involving current and future products and manufacturing facilities. In addition, sales of Amgen's products are affected by reimbursement policies imposed by third party payors, including governments, private insurance plans and managed care providers, and may be affected by domestic and international trends toward managed care and healthcare cost containment as well as possible U.S. legislation affecting pharmaceutical pricing and reimbursement. Government regulations and reimbursement policies may affect the development, usage and pricing of Amgen's products. Furthermore, Amgen's research, testing, pricing, marketing and other operations are subject to extensive regulation by domestic and foreign government regulatory authorities. Amgen or others could identify side effects or manufacturing problems with its products after they are on the market. In addition, Amgen competes with other companies with respect to some of its marketed products as well as for the discovery and development of new products. Discovery or identification of new product candidates cannot be guaranteed and 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. In addition, while Amgen routinely obtain patents for its products and technology, the protection offered by its patents and patent applications may be challenged, invalidated or circumvented by its competitors. Further, some

raw materials, medical devices and component parts for Amgen's products are supplied by sole third party suppliers.

The statements in this press release that are not historical facts are forward-looking statements based on current expectations of future events that involve risks and uncertainties including, without limitation, risks associated with the inherent uncertainty of pharmaceutical research, product development, manufacturing, and commercialization, and economic conditions, including interest and currency exchange rate fluctuations, the impact of competitive or generic products, product liability and other types of lawsuits, the impact of legislative and regulatory compliance and obtaining approvals, and patents, and other risks and uncertainties, including those detailed from time to time in Wyeth's periodic reports, including quarterly reports on Form 10-Q and the Annual Report on Form 10-K, filed with the Securities and Exchange Commission. Actual results may vary materially from the forward-looking statements. Wyeth assumes no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise.

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For further information, please contact:

Media: 805-447-4587

Wyeth Pharmaceuticals

Investors: 800-84-AMGEN

Douglas Petkus (media)

484/865-5140

Justin Victoria (investors)

973/660-5340

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