Court Rules in Amgen's Favor in TKT Litigation; Affirms Validity of EPO Patents| Amgen

Court Rules in Amgen's Favor in TKT Litigation; Affirms Validity of EPO Patents

THOUSAND OAKS, Calif.--(BUSINESS WIRE)--Oct. 15, 2004--Amgen, Inc. (NASDAQ:AMGN), the world's largest biotechnology company, today announced that Judge William G. Young of the U.S. District Court of Massachusetts in Boston ruled in its favor in the patent litigation suit against Transkaryotic Therapies Inc. ("TKT") and Aventis Pharmaceuticals Inc. The Court found Amgen's patent claims valid and infringed by TKT and Aventis.

Today's decision addressed the issues remanded to the District Court from the U.S. Court of Appeals for the Federal Circuit and focused on the validity of two product patents on erythropoietin and the validity and infringement of two patents with claims to production of erythropoietin. The District Court found all the patents valid and the process patents infringed. The result of this decision, coupled with earlier decisions, is that four Amgen patents on erythropoietin have been held valid, enforceable, and infringed.

This ruling confirms the strength of Amgen's patent rights on erythropoietin and protects Amgen's breakthrough inventions that have helped over a million people worldwide. Amgen will continue to vigorously enforce its intellectual property.

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.

CONTACT: Amgen, Thousand Oaks
Christine Cassiano, 805-447-4587 (media)
Laura Biswas, 805-447-1060 (investors)