News Release

ENBREL (etanercept) long-term clinical trial data

Peer-Reviewed Publication

Immunex Corporation

BOSTON - Data from patients receiving ENBREL® (etanercept) for as long as 41 months were presented at the 63rd National Scientific Meeting of the American College of Rheumatology (ACR) today.

The FDA approved ENBREL on November 2, 1998 to treat moderately to severely active rheumatoid arthritis in patients who have an inadequate response to one or more disease-modifying anti-rheumatic drugs (DMARDs). The FDA included children and teen-agers (age 4-17 years) in the ENBREL label when it granted the drug a new indication on May 28, 1999 for the treatment of moderately to severely active polyarticular-course juvenile rheumatoid arthritis patients who have had an inadequate response to one or more DMARDs.

Study participants were treated with 25 mg of ENBREL twice weekly and continue to be followed in an ongoing study being conducted in the United States and Canada. Patients described in this presentation had moderate to severely active RA and had failed at least one DMARD. The data presented have not been reviewed by the Food and Drug Administration.

Response to ENBREL was sustained over time. Of patients treated for 12 months (n=480), 72, 47 and 21 percent achieved 20, 50 and 70 percent reductions in ACR response criteria, respectively. Of patients treated for 30 months (n=83), 80, 60 and 33 percent achieved 20, 50 and 70 per cent reductions in ACR response criteria, respectively. In controlled trials, of patients treated for 3 months (n=78), 62, 41 and 15 percent achieved 20, 50 and 70 percent reductions in ACR response criteria, respectively.

No significant differences in rate or type of adverse event were seen when patients continued to receive ENBREL over time. Infections occurred at a rate of 1.55 per patient year compared to 1.82 in controlled clinical trials. Headache occurred at a rate of 0.27 per patient year compared to 0.68 in controlled trials. Serious infections occurred at a rate of 0.050 per patient year compared to 0.043 per patient year in controlled trials. There were nine reports of cancer, similar to the expected number (10.7) calculated from the NCI SEER database. None of the patients has developed a new autoimmune rheumatic disease.

IN POSTMARKETING USE, SERIOUS INFECTIONS AND SEPSIS, INCLUDING FATALITIES, HAVE BEEN REPORTED. MANY OF THESE EVENTS OCCURRED IN PATIENTS PREDISPOSED TO INFECTIONS, SUCH AS THOSE WITH ADVANCED OR POORLY CONTROLLED DIABETES. DISCONTINUE ENBREL IN PATIENTS WITH SERIOUS INFECTIONS OR SEPSIS. DO NOT START ENBREL IN THE PRESENCE OF SEPSIS, INFECTION (INCLUDING CHRONIC OR LOCALIZED), OR ALLERGY TO ENBREL OR ITS COMPONENTS. USE CAUTION IN PATIENTS PREDISPOSED TO INFECTION. The most frequent adverse events in adult clinical trials in rheumatoid arthritis (n=349) were injection site reactions (ISR) 37%, infections (35%) and headache (17%). Malignancies were rare (<1%). Only the rate of ISR was higher than placebo.

In a JRA study (n=69), infections (62%), headache (19%), abdominal pain (19%), vomiting (13%) and nausea (9%) occurred more frequently than in adults. The types of infections reported in JRA patients were generally mild and consistent with those commonly seen in outpatient pediatric populations. Serious adverse reactions reported rarely were varicella (3%), gastroenteritis (3%), depression/personality disorder (1%), cutaneous ulcer (1%), and esophagitis/gastritis (1%).

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Immunex is the manufacturer of ENBREL. Immunex and Wyeth-Ayerst Laboratories market ENBREL in North America. Other Wyeth-Ayerst affiliates will market ENBREL outside of North America. Additional information about ENBREL, including full prescribing information, can be found on the company-sponsored website at ( www.enbrel.com ) or by calling toll-free 1-888-4ENBREL (1-888-436-2735).

Immunex is a biopharmaceutical company dedicated to developing immune system science to protect human health. The company's products offer hope to patients with cancer, inflammatory and infectious diseases.

American Home Products Corporation's Wyeth-Ayerst division is a major research-oriented pharmaceutical company with leading products in the areas of women's health care, cardiovascular disease therapies, central nervous system drugs, anti-inflammatory agents, vaccines and generic pharmaceuticals.

American Home Products owns a majority interest in Immunex. AHP is one of the world's largest research-based pharmaceutical and health care products companies. It is a leader in the discovery, development, manufacturing and marketing of prescription drugs and over-the-counter medications. It is also a leader in vaccines, biotechnology, agricultural products and animal health care.

NOTE: This release contains forward-looking statements that involve risks and uncertainties, including risks associated with clinical development, regulatory approvals, patent litigation, product commercialization and other risks described from time to time in the SEC reports filed by Immunex, including the most recently filed 10-K and 10-Q. For more information, please refer to www.immunex.com .


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