Enzon to Present Preclinical Data From PEG-SN38 and PEGylation Technology Studies at AACR Meeting.

BRIDGEWATER, N.J. -- Enzon Pharmaceuticals, Inc. (Nasdaq: ENZN) announced today that four posters containing preclinical data will be presented at the 2007 Annual Meeting of the American Association for Cancer Research (AACR) to be held from April 14 - 18, 2007 in Los Angeles, CA.

Details of the presentations are as follows:

* Abstract #1494: EZN-2208, a novel polyethyleneglycol-SN38 conjugate, has potent antitumor activity in a panel of human tumor xenografts (Poster displayed on Sunday, April 15, 2007, 1:00 PM - 5:00 PM, PT, Poster Section 30, Poster Board 8.)

* Abstract #1496: EZN-2208, a novel poly ethylene glycol-SN38 conjugate, improves pharmacological properties of SN38 in mice and rats. (Poster displayed on Sunday, April 15, 2007, 1:00 PM - 5:00 PM, PT, Poster Section 30, Poster Board 10.)

* Abstract #4731: Customized positive PEG linkers for the delivery of antisense molecules (Poster displayed on Tuesday, April 17, 2007, 1:00 PM - 5:00 PM, PT, Poster Section 25, Poster Board 14.)

* Abstract #4726: In vitro and in vivo evaluation of PEGylated anti-Bcl2 siRNA conjugates in a Bcl-2 over-expressing lung cancer model (Poster displayed on Tuesday, April 17, 2007, 1:00 PM - 5:00 PM, PT, Poster Section 25, Poster Board 9.)

About Enzon

Enzon Pharmaceuticals, Inc. is a biopharmaceutical company dedicated to the development, manufacturing, and commercialization of important medicines for patients with cancer and other life-threatening conditions. Enzon has a portfolio of four marketed products, Oncaspar[R], DepoCyt[R], Abelcet[R] and Adagen[R]. The Company's drug development programs utilize several cutting-edge approaches, including its industry-leading PEGylation technology platform used to create product candidates with benefits such as reduced dosing frequency and less toxicity. Enzon's PEGylation technology was used to develop two of its products, Oncaspar and Adagen, and has created a royalty revenue stream from licensing partnerships for other products developed using the technology. Enzon also engages in contract manufacturing for several pharmaceutical companies to broaden the Company's revenue base. 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 12-month period ended December 31, 2006. 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.