FOR IMMEDIATE RELEASE

THOUSAND OAKS, Calif., and COLLEGEVILLE, Pa., June 20, 2003 - Amgen (NASDAQ: AMGN) and Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE), today announced results of a new study assessing the efficacy of combination treatment with ENBREL. (etanercept) and methotrexate in rheumatoid arthritis (RA) patients, compared with ENBREL or methotrexate alone. One-year results of TEMPO, (Trial of Etanercept and Methotrexate with Radiographic Patient Outcomes), were presented today at a satellite symposium during the European League Against Rheumatism meeting in Lisbon, Portugal.

Eighty percent of patients treated with combination therapy experienced no radiographic progression through one year, compared to 68 percent of patients treated with ENBREL alone and 57 percent of patients treated with methotrexate.

Both combination therapy and ENBREL monotherapy provided significant inhibition of joint damage (-0.5 mean change and 0.5 mean change from baseline in total Sharp score, respectively), compared with methotrexate alone (2.8 mean change in total Sharp score). A Sharp score is an X-ray measurement of changes in total joint damage as assessed by bone erosions and joint space narrowing.

"The radiographic data in this study demonstrate that ENBREL in combination or alone had a more significant impact on the progression of structural damage in RA versus methotrexate alone," said Dr. Désirée van der Heijde, professor of rheumatology, University of Maastricht in the Netherlands. "In fact, the combination of ENBREL and methotrexate provided some of best radiographic responses noted to date. This is especially important considering the characteristics of RA as a chronic, progressively disabling disease."

Other responses were evaluated by 20 percent, 50 percent and 70 percent ACR score improvements in the signs and symptoms of RA (known as ACR20, ACR50 and ACR70 scores).

After 52 weeks of treatment, an ACR20 score was achieved by 85 percent of patients treated with the ENBREL and methotrexate combination, 76 percent of patients treated with ENBREL alone and 75 percent of patients treated with methotrexate.

Sixty-nine percent of patients on combination therapy reached an ACR50 score at one year, versus 48 percent and 43 percent with ENBREL alone and methotrexate respectively. ACR70 scores were 43 percent, 24 percent and 19 percent with the ENBREL combination, ENBREL alone, and methotrexate respectively.

"These data provide new, compelling evidence of the importance of ENBREL as a first-line therapy," said Dr. Victoria Kusiak, vice president of global medical affairs and North American medical director of Wyeth Pharmaceuticals. "Since its approval in 1998, physicians have experienced the flexibility and efficacy of using ENBREL alone or in combination with methotrexate."

Study Design

The multi-center, double-blind, Phase 3 study randomized 682 patients with RA for a period of one year to receive ENBREL (25 mg twice weekly) plus methotrexate (mean dose of 17 mg once weekly), ENBREL (25 mg twice weekly) plus placebo capsules once weekly, or methotrexate (mean dose of 17 mg once weekly) plus placebo injections twice weekly.

"This study shows that ENBREL, either in combination with methotrexate or alone, provided patients not only symptomatic relief but significant inhibition of joint damage," said Dr. Beth Seidenberg, Amgen senior vice president of development.

Adverse events were similar to those reported in previous clinical trials of ENBREL in patients with RA.

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.

Rheumatoid arthritis is a chronic disease that causes pain, stiffness, swelling, and limitation in the motion and function of multiple joints. If left untreated or improperly treated, RA can produce serious destruction of one or more joints, which frequently leads to permanent disability, significantly impacting quality of life.

ABOUT ENBREL

ENBREL is the only fully human, soluble TNF receptor approved to reduce the signs and symptoms and inhibit the 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 for first line treatment of 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 since becoming commercially available four 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.

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 infection

• Serious 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 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 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 non-prescription 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 obtains 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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