Enzon secures proprietary position in SCA protein technology through 2013.

PISCATAWAY, NJ--(BUSINESS WIRE)--July 17, 1996--Enzon, Inc. (NASDAQ/NMS:ENZN) announced today that it has received three additional United States patents for its Single-Chain Antigen-Binding (SCA(R)) protein technology, which is one of the Company's proprietary core technologies.

SCA proteins, like monoclonal antibodies, (MAbs), are used to deliver therapeutic agents to target disease sites in the body. Enzon believes SCA proteins offer significant advantages over conventional MAbs such as greater tumor penetration for cancer imaging and therapy, more specific localization to targeted disease sites in the body, decreased immunogenic reactions, and easier, more cost effective manufacturing processes. In addition to these advantages, because SCA proteins are developed at the gene level, they are better suited for targeted delivery of gene therapy vectors and fully-human SCA proteins can be isolated directly, with no need for costly "humanization" procedures. Also, many gene therapy methods require that proteins be produced in active form inside cells. SCA proteins can be produced through intracellular expression (inside cells) more readily than MAbs.

The SCA patents issued were U.S. Patent No. 5,534,621 covering immunopurification methods, U.S. Patent No. 5,518,889 covering immunoassay methods and U.S. Patent No. 5,455,030 covering immunotherapeutic methods.

Enzon has licensed the SCA protein technology primarily on a non-exclusive basis to more than a dozen companies including several global pharmaceutical companies such as Baxter Healthcare, Eli Lilly, Bristol-Myers Squibb, and the Gencell division of Rhone-Poulenc Rorer. Under these licenses, the Company has received approximately $6 million in up front payments and is entitled to receive additional payments upon achievement of specified development milestones and royalties on sales of any future products developed that utilize Enzon's SCA technology.

Clinical trials for seven products using SCA protein technology have been started by licensees as well as academic institutions. Some of the areas being explored are cancer therapy, cardiovascular indications and AIDS.

"These three new patents extend our exclusive coverage of SCA protein technology," said Peter G. Tombros, president and CEO, Enzon, Inc. "The recent application of this technology in the gene therapy area opens up additional licensing opportunities. Research being conducted at Enzon in this field may result in additional patents, which could extend our proprietary position beyond the year 2013."

Enzon, Inc., is a biopharmaceutical company that develops, manufactures and markets enhanced therapeutics for life-threatening diseases, primarily in the areas of oncology, genetic diseases and blood substitutes. Enzon is currently developing a hemoglobin-based oxygen carrier and has two FDA approved drugs -- ADAGEN(R), a treatment for Severe Combined Immunodeficiency Disease and ONCASPAR(R), for the treatment of Acute Lymphoblastic Leukemia, which is being marketed by Rhone-Poulenc Rorer Pharmaceuticals, Inc. The Company also pursues commercialization of its proprietary technologies through strategic partnering. Enzon is headquartered in Piscataway, NJ.

CONTACT: Enzon, Inc.

Kimberly Cooper

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