Enzon Announces FDA Approval of Intravenous Administration of ONCASPAR(R); New Label Provides Clinicians with an Important New Option for Administering ONCASPAR(R) to Pediatric Patients

Enzon Pharmaceuticals, Inc. (Nasdaq: ENZN) announcedtoday that the U.S. Food and Drug Administration (FDA) has approved alabeling change for its pediatric oncology drug, ONCASPAR(R). The newlabeling allows for administration via the intravenous (IV) route. IVadministration provides clinicians with an important new option thatwill potentially reduce the number of injections for pediatric cancerpatients who require ONCASPAR in their treatment regimen. Previously,ONCASPAR's administration was limited to intramuscular administration,which involves injecting the drug directly into the muscle and isoften painful to patients.

ONCASPAR is a PEG-enhanced version of the naturally occurringenzyme L-asparaginase. L-asparaginase is an enzyme that depletes theamino acid asparagine, which certain leukemic cells are dependent uponfor survival. ONCASPAR was granted a marketing license by the U.S.Food and Drug Administration in February 1994 to treat patients withacute lymphoblastic leukemia who require L-asparaginase in theirtreatment regimen, but have developed hypersensitivity to native formsof L-asparaginase. Through its proprietary PEGylation technology,Enzon designed ONCASPAR to offer therapeutic advantages overunmodified L-asparaginase. In addition to reduced immunogenicity,ONCASPAR provides a more convenient, patient-friendly dosing regimenthat allows for administration every 14 days, versus twice weekly forunmodified L-asparaginase. Enzon's specialized oncology sales forcemarkets ONCASPAR in North America.

About 35,000 new cases of leukemia will be diagnosed in the UnitedStates during 2005. Of these about 4,000 will be acute lymphoblasticleukemia (also called acute lymphocytic leukemia or ALL). Although ALLis mainly a childhood leukemia, about one-third of new cases willoccur in adults.

About Enzon

Enzon Pharmaceuticals, Inc. is a biopharmaceutical companydedicated to the development and commercialization of therapeutics totreat patients with cancer and other life-threatening diseases.Enzon's specialized sales force markets ABELCET(R), ONCASPAR(R),ADAGEN(R), and DEPOCYT(R) in North America. In addition, Enzon alsoreceives royalties on sales of PEG-INTRON(R), marketed bySchering-Plough Corporation, and MACUGEN(R), marketed by EyetechPharmaceuticals and Pfizer Inc. Enzon's product-driven strategyincludes an extensive drug development program that leverages itsproprietary technologies, including a next-generation PEGylationplatform that utilizes linkers designed to release compounds at acontrolled rate. Enzon complements its internal research anddevelopment efforts with strategic initiatives, such as partnershipsdesigned to broaden its revenue base or provide access to promisingnew technologies or product development opportunities. Furtherinformation about Enzon and this press release can be found on theCompany's web site at www.enzon.com.

All information in this press release is as of November 10, 2005and the Company undertakes no duty to update this information.