Positive Results of Phase I Study Presented At American College of Cardiology Conference

SEATTLE -- Immunex Corporation (NASDAQ:IMNX and Wyeth-Ayerst Laboratories announced today that they are beginning a Phase II/III clinical trial with ENBREL (etanercept) in chronic heart failure patients, one of the first large-scale studies undertaken to evaluate cytokine inhibition, an entirely new approach to studying chronic heart failure. This study will be based on positive results of a Phase I study presented today at the annual conference of the American College of Cardiology in New Orleans, LA.

Results of the double-blind, randomized, placebo-controlled multi-dose Phase I safety study in 47 heart failure patients demonstrated that ENBREL was well tolerated. The incidence of adverse events was similar in all treatment groups. The study was conducted by Dr. Douglas Mann and Dr. Guillermo Torre at Baylor College of Medicine, and Dr. Arthur M. Feldman at University of Pittsburgh Medical Center.

The 47 patients were New York Health Assessment (NYHA) class III-IV and were randomized to be treated for three months with twice weekly injections of either ENBREL at 5mg/m2, 12mg/m2 or placebo. At three months, measurements of clinical activity suggested consistent improvement for patients on ENBREL in NYHA classification, left ventricular ejection fraction, quality of life, and in a clinical composite score. In addition, there appeared to be a positive dose response in each of the categories above. Based on the results of the study, and additional clinical and preclinical data associating elevated TNF levels with chronic heart failure, the two companies have elected to proceed to a Phase II/III multicenter trial.

"We are pleased that the results of the multidose Phase I study supported moving into a Phase II/III multicenter trial," said Peggy Phillips, senior vic
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Contact: Pam Rabe
prabe@immunex.com
206-470-4131
Immunex Corporation
8-Mar-1999