Enzon Announces President to Lead SCA Ventures Division.

PISCATAWAY, N.J.--(BUSINESS WIRE)-- March 11, 1999--Enzon, Inc. (Nasdaq:ENZN) announced today that Josef Bossart, Ph.D., has been appointed President of SCA(R) Ventures. SCA Ventures will be a subsidiary of Enzon that will focus on commercializing Enzon's extensive Single-Chain Antigen-Binding (SCA(R)) Protein technology.

As SCA Venture's president, Dr. Bossart will report to Peter Tombros, president and chief executive officer of Enzon, and will be responsible for developing and implementing a full-spectrum business strategy for SCA Ventures. Dr. Bossart brings to SCA Ventures over 20 years experience in pharmaceutical and biotechnology management. Dr. Bossart is currently serving as Vice President and Chief Business Officer of GeneMedicine, Inc., a publicly traded gene therapy company, and intends to join SCA Ventures following the completion of GeneMedicine's merger to Megabios Corp. Prior to joining GeneMedicine, Dr. Bossart spent more than 14 years with Rhone-Poulenc Rorer in marketing, general management and business development positions, including vice president of business and marketing development for the RPR Gencell division.

"We believe Jo is the ideal person to lead SCA Ventures and capture the full potential of our proprietary position in the field of SCA proteins," said Peter Tombros, Enzon's president and chief executive officer. "We believe there is significant value in the use of SCA proteins in therapeutic products and for drug discovery, and have decided to focus more resources on this area. This value may be enhanced by the marriage of SCA proteins with our proprietary PEG Modification technology to create a new class of protein therapeutics offering a wide spectrum of therapeutic benefits."

"I was particularly attracted to Enzon by the multidimensional business opportunities and therapeutic potential offered by Enzon's SCA technology," said Josef Bossart. "SCA Ventures should be able to quickly develop a substantial licensing business based on the use of SCA for screening libraries in drug discovery programs. Additional licensing opportunities are offered by the application of SCA technology for the development of in vivo and in vitro diagnostic agents. The greatest opportunity and attention though will be placed on in-house clinical development of 'next generation' products based on the unique properties of SCA proteins."

SCA proteins are used to deliver therapeutic agents to target disease sites in the body. Enzon believes SCA proteins offer significant advantages over conventional Monoclonal Antibodies (MAbs), such as greater tumor penetration for cancer imaging and therapy, greater specificity 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 well 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, once appropriate genes are delivered, SCA proteins can be produced more readily than MAbs. The recent application of this technology in the gene therapy area opens up additional licensing opportunities for Enzon. Additionally, SCA proteins have been utilized in the development of phage display library technology for isolation of binding specificities. This has made it possible to isolate human high-affinity SCA proteins to virtually any target antigen using phage display library technology. Enzon currently has several licensees for its first generation SCA technology. Among the licensees, Alexion Pharmaceuticals, has recently announced initiation of a Phase IIb clinical trial of its lead anti-inflammatory complement inhibitor drug candidate 5G1.1-SC in patients undergoing cardiopulmonary bypass during coronary artery bypass graft. Other licensees include Baxter Healthcare Corporation, Bristol-Myers Squibb Company, Eli Lilly & Company, and Rhone-Poulenc Rorer Pharmaceuticals, Inc.

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. 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, including PEG-INTRON A (pegylated interferon alfa-2b