Enzon Announces Schering-Plough Submits U.S. Application for PEG-INTRON for the Treatment of Chronic Hepatitis C

Enzon Announces Schering-Plough Submits U.S. Application for PEG-INTRON for the Treatment of Chronic Hepatitis C

PISCATAWAY, N.J.--(BUSINESS WIRE)--Jan. 5, 2000--Enzon, Inc. (NASDAQ: ENZN - news) announced today that Schering-Plough Corporation (NYSE: SGP - news) has submitted a Biologics License Application (BLA) on December 23, 1999 to the U.S. Food and Drug Administration (FDA) seeking marketing approval for PEG-INTRON® (PEG-interferon alfa-2b) Powder for Injection for the treatment of chronic hepatitis C in patients 18 years of age or older with compensated liver disease.

PEG-INTRON is a modified form of Schering-Plough's INTRON® A (interferon alfa-2b, recombinant) Injection that was developed using Enzon's PEG technology to have longer-acting properties. The application proposes administration of PEG-INTRON subcutaneously once weekly for one year.

Schering-Plough previously reported that it has submitted a centralized Marketing Authorization Application for PEG-INTRON to the European Union's (EU) European Agency for the Evaluation of Medicinal Products (EMEA). Approval of the centralized Marketing Authorization Application for PEG-INTRON would result in unified labeling that would be valid in all 15 EU-Member States.

Under the Company's licensing agreement with Schering-Plough, Enzon is entitled to royalties on worldwide sales of PEG-INTRON and milestone payments. The filing of the BLA by Schering-Plough triggers a $1 million milestone payment to Enzon. Enzon will receive an additional $2 million milestone payment upon approval of PEG-INTRON.

Schering-Plough is continuing its development of PEG-INTRON as combination therapy with REBETOL® (ribavirin, USP) for hepatitis C, which is currently in a multi-national Phase III clinical trial. In addition, PEG-INTRON is in Phase III clinical trials for two cancer indications, malignant melanoma and chronic myelogenous leukemia (CML), as well as in early stage trials for various solid tumors and other forms of leukemia.

"This is a significant event in the development of PEG-INTRON. The speed with which Schering-Plough has progressed the product further demonstrates their leadership position in the hepatitis market," said Peter G. Tombros, Enzon's president and chief executive officer.

INTRON A is a recombinant version of naturally occurring alpha interferon, which has been shown to exert both antiviral and immunomodulatory effects. Schering-Plough markets INTRON A, the world's largest-selling alpha interferon, for 16 major antiviral and anticancer indications worldwide.

Some four million Americans are infected with the hepatitis C virus and approximately 70 percent of infected patients go on to develop chronic liver disease, according to the Centers for Disease Control and Prevention (CDCP). Hepatitis C infection contributes to the deaths of an estimated 8,000 to 10,000 Americans each year. This toll is expected to triple by the year 2010 and exceed the number of annual deaths due to AIDS, according to the CDCP. The American Liver Foundation has reported that liver failure due to hepatitis C infection is the leading cause of liver transplants in the U.S.

Enzon is a biopharmaceutical company developing advanced therapeutics for life-threatening diseases through the application of its proprietary drug delivery and targeting technologies, PEG Modification, Pro Drug/Transport technology and Single-Chain Antigen-Binding (SCA®) Protein technology. Enzon's research activities are focused primarily in the area of oncology. In addition to two FDA approved products, Enzon has several products in various stages of clinical development by itself and with partners. Enzon develops and markets products on its own and through its alliance partners, which in addition to Schering-Plough include Alexion Pharmaceuticals, Baxter Healthcare, Bristol-Myers Squibb, Eli Lilly, and Rhone-Poulenc Rorer Pharmaceuticals.

Certain statements made in this press release related to potential government approvals, market potential, commercialization and sales revenues of medical products and biologics, as well as their therapeutic applications and outcomes, are forward-looking and are made pursuant to the safe harbor provisions of the Securities Litigation Reform Act of 1995. Such statements involve risks and uncertainties, which may differ materially from those set forth in these statements. In addition, the economic, competitive, governmental, technological and other factors identified in the Company's filings with the Securities and Exchange Commission could affect such results.