Enzon Opens Pediatric Study of PEG-SN38

Enzon Pharmaceuticals, Inc. (Nasdaq: ENZN) today announced that the first patient has been treated in the Phase 1 study of PEG-SN38 for pediatric cancer patients. PEG-SN38 or EZN-2208 is Enzon’s PEGylated form of SN38, the active metabolite of the cancer drug Camptosar^® (irinotecan HCl injection). The study is designed to find the recommended dose of PEG-SN38 in pediatric patients. The PEG-SN38 compound is currently being evaluated in Phase 2 studies for metastatic colorectal and breast cancer.

"We are excited about the potential PEG-SN38 can have in the pediatric setting,” said Ivan Horak, Enzon's president of research and development. "Given PEG-SN38’s safety profile and the unmet medical need in pediatric patients, this compound may play an important role in the future treatment of children who have cancer.”

"Currently, there are very few treatment options available for children suffering from recurrent cancer. We are excited to be taking this important first step in evaluating the novel PEG-SN38 compound with the long-term hope of improving the outcome for children with cancer,” said Dr. Ro Bagatell, The Children’s Hospital of Philadelphia.

For more information on this study, or to find a participating center and eligibility criteria, please visit www.clinicaltrials.gov.

About Enzon

Enzon Pharmaceuticals, Inc. is a biopharmaceutical company dedicated to developing important medicines for patients with cancer. Enzon’s drug development programs utilize several cutting-edge approaches, including its industry-leading PEGylation technology platform and the Locked Nucleic Acid (LNA) technology. Enzon’s receives a royalty revenue stream from licensing partnerships for other products developed using the proprietary PEGylation technology. Further information about Enzon and this press release can be found on the Company’s web site at www.enzon.com.

Forward Looking Statements

There are forward-looking statements contained herein, 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 involve known and unknown risks, uncertainties and other factors that may cause actual results, events or developments to be materially different from the future results, events or developments indicated in such forward-looking statements. Such factors include, but are not limited to: the timing, success and cost of clinical studies; the ability to obtain regulatory approval of products; market acceptance of, and continuing demand for, Enzon’s products and the impact of competitive products and pricing. A more detailed discussion of these and other factors that could affect results is contained in our filings with the U.S. Securities and Exchange Commission, including our annual report on Form 10-K for the year ended December 31, 2008. 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.