Enzon to Launch CLEAR II Registry; New Initiative Reinforces Commitment to Improving Antifungal Research and Clinical Outcomes.

Business Editors/Health/Medical Writers/High-Tech Writers

BRIDGEWATER, N.J--(BUSINESS WIRE)--March 24, 2004

Enzon Pharmaceuticals, Inc. (NASDAQ: ENZN) announced today a major new initiative to build upon the value of its CLEAR(R) (Collaborative Exchange of Antifungal Research) patient registry with the launch of CLEAR II(TM). CLEAR II is a multi-center registry developed by and for clinicians to share and exchange information regarding the clinical course of invasive fungal infections and clinical experience with Enzon's marketed antifungal ABELCET(R) (Amphotericin B Lipid Complex Injection), as well as other antifungal agents.

Enzon's CLEAR database, which was completed in 2000, is one of the most comprehensive registries in fungal disease. CLEAR encompasses prospectively-gathered data from a total of 3,514 patient records, collected in the United States and Canada from 1996 to 2000. The registry was initially designed and administered by a steering committee comprised of national thought leaders in infectious disease, hematology, and oncology, with patient enrollment from over 150 institutions.

The CLEAR database supports the efficacy and safety of ABELCET across a wide spectrum of fungal pathogens (both yeasts and molds) and broad spectrum of patients. Additionally and of particular significance, the CLEAR database also documents the efficacy and safety of ABELCET in rapidly emerging, more difficult to treat and often treatment resistant pathogens such as Fusarium, Zygomycetes, and Candida. The CLEAR registry reflects the largest known registry in these emerging fungal pathogens.

Together with former steering committee members, clinicians, and other program advisors, Enzon developed CLEAR II. CLEAR II will now take advantage of the speed and flexibility of web-based data collection to provide participating research centers with online, real-time data that will be collected from patients across multiple sites across North America and accessed via a new website, www.clearii.com. Unlike the CLEAR database, which is limited to clinical experience with ABELCET, CLEAR II will also include data on patients treated with other antifungal agents. The Company expects that the enrollment of new patients in the CLEAR II registry will begin during the first half of calendar 2004. The registry will be previewed to clinicians from around the world at the annual scientific meeting, Focus on Fungal Infections (FOFI) 14, being held March 24 through March 26 in New Orleans, LA.

"Enzon is committed to the continued expansion of this important initiative and establishing ourselves as a premier partner in antifungal research," said Clarke Atwell, Enzon's vice president of marketing and sales. "By working together with the clinicians who are faced with the challenges of treating these life-threatening infections we feel we have developed an important new tool that will enable the medical community to share real-time data and clinical experiences to help define treatment strategies that ultimately may save more lives."

To assist Enzon with the CLEAR II project, the Company has partnered with La Jolla, California-based ProSanos Corporation.

About Invasive Fungal Infections

Invasive fungal infections are life-threatening complications often affecting patients with compromised immune systems, such as those suffering from cancer, HIV, and recipients of lung or bone marrow transplants, and others. They can be caused by a multitude of different fungal pathogens that attack the patient's weakened immune system. Effective treatment is critical and can mean the difference between life and death, and often must be initiated even in the absence of a specific diagnosis.

About ABELCET (amphotericin B lipid complex injection)

ABELCET was approved for use by the U.S. Food and Drug Administration (FDA) in November 1995. It is a lipid-based formulation of amphotericin B. Abelcet is the market leader among the 3 commercially available lipid-based formulations of amphotericin B. ABELCET offers clinicians the efficacy of amphotericin B combined with a greatly improved safety profile. ABELCET is indicated for the treatment of invasive fungal infections in patients who are refractory to or intolerant of conventional amphotericin B therapy. The adverse events most commonly reported with ABELCET are transient chills and/or fever during infusion of the drug. ABELCET is contraindicated in patients who have shown hypersensitivity to amphotericin B or any other component in the formulation. Please see full prescribing information before using ABELCET or any product mentioned in this press release.

About Enzon Pharmaceuticals

Enzon Pharmaceuticals is a biopharmaceutical company dedicated to the discovery, development and commercialization of therapeutics to treat life-threatening diseases. The Company has developed or acquired a number of marketed products, including PEG-INTRON(R), marketed by Schering-Plough, and ABELCET(R), ONCASPAR(R), ADAGEN(R), and DEPOCYT(R), which are all marketed in North America by Enzon's hospital and oncology sales forces. Enzon's science-focused strategy includes an extensive drug development program that leverages the Company's macromolecular engineering technology platforms, including PEG modification and single-chain antibody (SCA(R)) technologies. Internal research and development efforts are complemented by strategic transactions that provide access to additional products, projects, and technologies. Enzon has several drug candidates in various stages of development, independently and with partners. For further information on Enzon please refer to the Company's website at www.enzon.com.

There are forward-looking statements contained herein that are not based on historical fact, including without limitation statements containing the words "believes," "may," "plans," "will," "estimates," "continue," "anticipates," "intends," "expects," 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 discussed above. Such factors include the risk that Enzon may not be able to enroll a sufficient number of patients in the CLEAR II registry to make it a clinically valuable tool, as well as those described in Enzon's Form 10-K and Forms 10-Q on file with the SEC. These factors should be considered carefully and readers are cautioned not to place undue reliance on such forward-looking statements. All information in this press release is as of March 24, 2004 and the Company undertakes no duty to update this information.