Enzon Reinforces Commitment to Improving Patient Outcomes in Fungal Disease by Reinitiating CLEAR® Registry

May 14, 2003

BRIDGEWATER, NJ – May 14, 2003 – Enzon Pharmaceuticals, Inc. (NASDAQ:ENZN) has announced a major new initiative to reactivate and expand the CLEAR® (Collaborative Exchange of Antifungal Research) registry, a multicenter database developed for clinicians to share and exchange information regarding the clinical course of invasive fungal infections and clinical experience with ABELCET® (Amphotericin B Lipid Complex Injection).

“Enzon is committed to an expansive new effort to not only explore and analyze the wealth of data already collected since the mid 1990s, but to aggressively expand the database in 2003 and beyond to help define treatment strategies that ultimately may save more patients’ lives,” remarked Arthur Higgins, President and Chief Executive Officer, Enzon Pharmaceuticals, Inc.

The existing CLEAR database is one of the most comprehensive registries in fungal disease. CLEAR encompasses prospectively-gathered data from a total of 3,514 patient records, collected from 1996-2000 in the United States and Canada. The registry was 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 nationwide.

Results from the CLEAR program were recently reviewed at a gathering of former steering committee members and program advisors, who met in New Orleans, Louisiana last month to discuss the existing data and recommendations for expanded program enrollment in 2003. It was noted, that the overall clinical response rates across a wide spectrum of fungal pathogens (both yeasts and molds) unequivocally support the efficacy and safety of ABELCET across the broadest spectrum of patients.

Of particular significance, the CLEAR database documents efficacy and safety of ABELCET in rapidly emerging, more difficult to treat pathogens such as Fusarium, Zygomycetes, and Candida infections that are resistant to standard treatments. The CLEAR experience reflects the largest known registry in these emerging fungal pathogens.

The expanded registry will provide an opportunity to collect further experience and outcome data on ABELCET, particularly in combination with other antifungal agents. Enzon Pharmaceuticals is committed to rapidly reestablishing the momentum of the CLEAR program, with the hope that ongoing research and new insights will ultimately yield more successful paradigms to improve treatment outcomes in invasive fungal disease.

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

ABELCET was approved for use by the US Food and Drug Administration (FDA) in November 1995. It 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.

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 ABELCET, which is marketed in North America by Enzon, and PEG-INTRON, marketed by Schering-Plough.

Enzon’s product-focused strategy includes an extensive drug development program that leverages the Company’s PEG modification and single-chain antibody (SCA®) 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.

Except for the historical information herein, the matters discussed in this news release include forward-looking statements that may involve a number of risks and uncertainties. Actual results may vary significantly based upon a number of factors, which are described in the Company’s Form 10-K, Form 10-Q’s and Form 8-K’s on file with the SEC, including without limitation, Enzon’s dependence on Schering-Plough’s effective marketing of PEG-INTRON; Enzon’s ability to sustain profitability; risks in obtaining and maintaining regulatory approval for indications and expanded indications, market acceptance of and continuing demand for Enzon's product, timing and results of clinical trials and the impact of competitive products and pricing, the NPS and Enzon businesses may not be integrated successfully; costs related to the proposed merger may be significant and greater than we expect; and the NPS or Enzon stockholders may fail to approve the proposed merger. All information in this press release is as of May 14, 2003, and the Company undertakes no duty to update this information.

Additional Information and Where to Find it

In connection with the proposed NPS/Enzon merger, NPS, Enzon, and Momentum Merger Corporation (which will be renamed by NPS and Enzon in connection with the proposed merger) have filed a joint proxy statement/prospectus with the Securities and Exchange Commission (the "SEC") in connection with the proposed merger. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS BECAUSE IT CONTAINS IMPORTANT INFORMATION ABOUT THE TRANSACTION. Investors and security holders may obtain a free copy of the joint proxy statement/prospectus (when it is available) and other documents filed by NPS and Enzon with the SEC at the SEC's web site at www.sec.gov or by contacting NPS at 801-583-4939 and through NPS' web site at www.npsp.com, or by contacting Enzon at 908-541-8678 and through Enzon's web site at www.enzon.com.

Enzon and its directors and executive officers may be deemed to be participants in the solicitation of proxies from the stockholders of Enzon and NPS in connection with the proposed merger transaction. Information regarding the special interests of these directors and executive officers in the transaction is included in the joint proxy statement/prospectus described above. Additional information regarding these directors and executive officers is also included in Enzon's proxy statement for its 2002 Annual Meeting of Stockholders, which was filed with the SEC on or about October 28, 2002. This document is available free of charge at the SEC's web site at www.sec.gov or by contacting Enzon at 908-541-8678.

NPS and its directors and executive officers also may be deemed to be participants in the solicitation of proxies from the stockholders of NPS and Enzon in connection with the transaction described herein. Information regarding the special interests of these directors and executive officers in the proposed merger transaction is included in the joint proxy statement/prospectus described above. Additional information regarding these directors and executive officers is also included in NPS' proxy statement for its 2002 Annual Meeting of Stockholders, which was filed with the SEC on or about April 19, 2002. This document is available free of charge at the SEC's web site at www.sec.gov or by contacting NPS at 801-583-4939 and through the NPS website at www.npsp.com.

Contact:
Susan Mesco, Director of Investor Relations, Enzon, 908-541-8678
Noonan Russo Euro Presence, 212-845-4239
Mark Vincent, Media Relations