Enzon Pharmaceuticals, Inc. to Present at 2012 World Congress and Expo on Biowaivers and Biosimilars

PISCATAWAY, NJ--(Marketwire - September 11, 2012) - Enzon Pharmaceuticals, Inc. (NASDAQ: ENZN) today announced that it will present at the 2012 World Congress and Expo on Biowaivers and Biosimilars, which is being held September 10-12 in San Antonio, TX. The Company was selected to give a presentation and overview of PEGylation, its Customized Linker Technology®, and its potential to create or enhance biobetter and biosimilar therapeutics by extending the benefit of this proprietary technology to a wider range of therapeutic molecules. Among other applications, PEGylation can be used to improve the therapeutic index and dosage profile of a proven marketed agent, resulting in a biobetter that is a new chemical entity with full patent protection. The presentation will be given by Hong Zhao, Ph.D., Enzon’s Senior Director of Chemistry on September 11, 2012 at 10:10 a.m. CT.

PEGylation, or bioconjugation of a molecule with PEG (polyethylene glycol), is a proven drug delivery technology pioneered by Enzon. To date, Enzon’s established technology and know-how have been used to develop eight marketed products with combined annual sales of over $3 billion. PEGylation has been successfully used on various pharmaceutical compounds including enzymes, peptides, small molecules, and antibody fragments to improve their pharmaceutical properties, including their therapeutic index.

In building a next generation of PEGylated products, Enzon has developed the industry leading releasable PEGylation technology utilizing its Customized Linker Technology, wherein PEG polymers are shed via a controlled release mechanism to release the intact parent drug. Releasable PEG linkers can not only provide a practical option to improve the pharmaceutical properties of parent molecules without the need for reengineering if the parent molecules are biologics, but can also be used as a way to predictably modify and release a wide range of therapeutic components. Further, releasable PEG linkers are designed to overcome the limitations of permanent PEGylation, such as diminished pharmacological properties of the modified molecule, and may result in reduced immunogenicity and optimized pharmacokinetics.

“PEGylation is a well-established drug delivery technology that has been shown to enhance the pharmaceutical properties of various drug molecules, resulting in improved products with demonstrated efficacy and dosing advantages for patients and healthcare providers,” said Dr. Hong Zhao, Senior Director of Chemistry at Enzon Pharmaceuticals. “By overcoming the challenges associated with permanent PEGylation, releasable linker technology expands the range of molecules to which this technology may be applied and, as a consequence, the range of biobetter and biosimilar products that may be developed. PEGylation should also be considered an important part of the life cycle management for many important products, as the resultant molecules are often new chemical entities eligible for patent protection.”

Enzon recently entered into collaboration agreements with Zhejiang Hisun Pharmaceuticals Co. Ltd and Molecular Templates, Inc. which provide for the research, development, and potential licensing of therapeutics that utilize the Company’s customized releasable PEGylation linker technology.

About Enzon’s Customized PEGylation Linker Technology

PEGylation has successfully been used on various pharmaceutical compounds, including enzymes, peptides and antibodies, to improve their pharmaceutical properties through the chemical attachment of polyethylene glycol (PEG) using our Customized Linker Technology. PEGylation technology employs proprietary chemical linkers designed to either release the native molecule at a controlled rate or provide permanent linkage that will maximize inherent activity of the parent molecule. In some cases, PEGylation can render a compound therapeutically effective, whereas the unmodified form had only limited clinical utility.

About Enzon

Enzon Pharmaceuticals, Inc. is a biotechnology company dedicated to the research and development of innovative therapeutics for patients with high unmet medical need. Enzon’s drug-development programs utilize two platforms: Customized PEGylation Linker Technology (Customized Linker Technology®) and third-generation mRNA-targeting agents utilizing the Locked Nucleic Acid (LNA) technology. Enzon currently has four compounds in human clinical development and multiple novel mRNA antagonists in preclinical research. Enzon receives royalty revenues from licensing arrangements with other companies related to sales of products developed using its proprietary Customized Linker Technology. Further information about Enzon and this press release can be found on the Company’s website at www.enzon.com.

Forward-Looking Statements

This press release contains, or may contain, forward-looking statements within the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release, other than statements that are purely historical, are forward-looking statements, which can be identified by the use of forward-looking terminology such as the words “believes,” “expects,” “may,” “will,” “should,” “potential,” “anticipates,” “plans,” or “intends” and similar expressions.

Such forward-looking statements are based upon management’s present expectations, objectives, anticipation, plans, hopes, beliefs, intentions or strategies regarding the future and are subject to known and unknown risks and uncertainties that could cause actual results, events or developments to be materially different from those indicated in such forward-looking statements. The results of preclinical data are not necessarily indicative of clinical efficacy. A more detailed discussion of these and other factors that could affect results is contained in Enzon’s filings with the U.S. Securities and Exchange Commission, including Enzon’s Annual Report on Form 10-K for the year ended December 31, 2011. These factors should be considered carefully and readers are cautioned not to place undue reliance on such forward-looking statements. No assurance can be given that the future results covered by the forward-looking statements will be achieved. All information in this press release is as of the date of this press release and Enzon does not intend to update this information.