| Enzon Announces PEG-INTRON(tm) Receives FDA Approval for the Treatment of Chronic Hepatitis C; First Pegylated Interferon Approved for Marketing in the United States
 PISCATAWAY, N.J.--(BUSINESS 
                                            WIRE)--Jan. 22, 2001--Enzon, Inc. (NASDAQ:ENZN) announced today that Schering-Plough Corporation (NYSE:SGP) has received U.S. Food and Drug Administration (FDA) approval for PEG-INTRON(TM) (peginterferon 
                                            alfa-2b) Powder for Injection as once-weekly monotherapy for the treatment of chronic hepatitis C in patients not previously treated with alpha interferon who have compensated liver disease and are at 
                                            least 18 years of age.
 
 PEG-INTRON is the first and only pegylated interferon approved for marketing in the United States. The product is expected to be available nationwide in early February 2001.
 
 PEG-INTRON is a longer acting form of Schering-Plough Corporation's INTRON(R) A that uses proprietary PEG technology developed by Enzon. Under the Company's licensing agreement with 
                                            Schering-Plough Corporation, Enzon is entitled to royalties on worldwide sales of PEG-INTRON and milestone payments. This approval triggers the final milestone payment of $2 million under the licensing 
                                            agreement.
 
 "While combination therapy with alpha interferon and ribavirin is a recognized standard of care for chronic hepatitis C, PEG-INTRON monotherapy offers an alternative to patients 
                                            whom combination therapy may be a contraindication or who are intolerant of this therapy," said John G. McHutchison, M.D., medical director, liver transplantation, division of gastroenterology and 
                                            hepatology, Scripps Clinic and Research Foundation, La Jolla, Calif. "As the first pegylated interferon product approved for marketing, PEG-INTRON provides a valuable addition to the therapies 
                                            available to physicians for treating this serious disease," Dr. McHutchison said. "We are pleased that our PEG technology will play such an important role in the treatment of patients afflicted 
                                            with this virus," said Peter G. Tombros, Enzon's president and chief executive officer. "Schering-Plough's rapid advancement of this product to the market offers evidence of the benefits that 
                                            our PEG technology may provide to compounds with delivery limitations."
 
 PEG-INTRON is administered subcutaneously once weekly for one year. The dose should be administered on the same day of 
                                            each week and may be self-administered by patients.
 
 The safety and efficacy of PEG-INTRON has been demonstrated in a randomized, controlled clinical study involving 1,219 adult patients with 
                                            chronic hepatitis C who were not previously treated with alpha interferon. The study compared PEG-INTRON (0.5, 1.0 or 1.5 mcg/kg) administered subcutaneously once weekly to Schering-Plough's INTRON(R) A 
                                            (interferon alfa-2b, recombinant) Injection (3 MIU) administered subcutaneously three times weekly. Patients were treated for 48 weeks and were followed for 24 weeks post-treatment. In the study, 
                                            patients receiving the 1.0 mcg/kg dose of PEG-INTRON achieved a 24 percent treatment response rate of sustained virologic response and ALT(1) normalization as compared to a 12 percent treatment response 
                                            rate in patients receiving INTRON A. The safety and efficacy of PEG-INTRON in combination with ribavirin have not been established.
 
 Nearly all study patients experienced one or more adverse 
                                            events. The incidence of serious adverse events was similar (about 12 percent) in all treatment groups. The most common adverse events associated with PEG-INTRON were "flu-like" symptoms, which 
                                            occurred in approximately 50 percent of patients; injection site irritation or inflammation, seen in 47 percent of patients; and depression, seen in 29 percent of patients.
 
 WARNING:
 Alpha 
                                            interferons, including PEG-INTRON, cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic and infectious disorders.  Patients should be monitored closely with periodic 
                                            clinical and laboratory evaluations.  Patients with persistently severe or worsening signs or symptoms of these conditions should be withdrawn from therapy.  In many but not all cases these 
                                            disorders resolve after stopping PEG-INTRON therapy.
 
 PEG-INTRON, recombinant interferon alfa-2b linked to a 12,000 dalton polyethylene glycol (PEG) molecule, is a once-weekly product designed 
                                            to optimize the balance between antiviral activity and elimination half-life.  Schering-Plough holds an exclusive worldwide license to PEG-INTRON.  Schering-Plough markets the product as 
                                            PEGINTRON(TM) in the European Union, where it received marketing approval in May 2000.  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 4 
                                            million Americans are infected with the hepatitis C virus (HCV) and approximately 70 percent of infected patients go on to develop chronic liver disease, according to the Centers for Disease Control and 
                                            Prevention (CDC). 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 CDC. The CDC has reported that HCV-associated end-stage liver disease is the most frequent indication for liver transplantation among adults.
 
 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(R)) protein technology.> In addition to PEG-INTRON, the Company also has two other approved products, ONCASPAR(R) for Acute 
                                            Lymphoblastic Leukemia (ALL) and ADAGEN(R) a treatment for a form of Severe Combined Immunodeficiency Disease (SCID), commonly known as the "Bubble Boy Disease". In addition to three FDA 
                                            approved products, Enzon has several products in various stages of clinical development by itself and with partners, including additional indications for PEG-INTRON with Schering-Plough. PEG-INTRON is 
                                            also in Phase III clinical trials being conducted by Schering-Plough for the treatment of malignant melanoma and chronic myelogenous leukemia. Enzon develops and markets products on its own and through 
                                            strategic alliances, which in addition to Schering-Plough Corporation, include Alexion Pharmaceuticals, Inc., Baxter Healthcare Corporation, Bristol-Myers Squibb Company, Eli Lilly & Company, and 
                                            Aventis.
 
 Except for the historical information herein, the matters discussed in this news release include forward-looking statements that may involve a number of risks and uncertainties. Actual 
                                            results may vary significantly based upon a number of factors which are described in the Company's Form 10-K, Form 10-Q's and Form 8-K on file with the SEC, including without limitation, risks in 
                                            obtaining and maintaining regulatory approval for the Company's products and expanded indications for such products, market acceptance of and continuing demand for Enzon's products and the impact of 
                                            competitive products and pricing. The forward-looking statements included in this news release provide the information included in such statements as of the date of this news release and the Company 
                                            disclaims any duty to update any of such statements.
 
 This release is also available at http://www.enzon.com
 
 (1) ALT: alanine aminotransferase, an enzyme that indicates ongoing liver 
                                            inflammation.
 
 
 
 
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                                    | When the Peg-Intron trials were over, several months ago, I began receiving calls from people who had been involved. These were the sickest group from which I have heard. On average they had viral 
                                            loads 3 times higher than when they started. They suffered the most severe disabling effects, far worse than interferon. People told me that they had to move their beds down stairs because they could not 
                                            climb the stairs, they expressed the need to hire people to come into their homes to care for them because they could not even comb their own hair.  As the study says, some of the effects may 
                                            continue even after you stop. I have heard from several people that they feel they are permently damaged from the stuff.  As most of you know I am opposed to this "cure" from the dark 
                                            ages, but let me reassure that this stuff is absolute poison and I urge you to avoid it.
 It is my option that it was created to help maintain market share, as Schering-Plough's patent on interferon 
                                            has run out and other companies are making it.
 Try it if you feel the need, when it fails, I will be here to help you recover from it and Hep C.
 
 Lloyd
 
 
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