Enzon Pharmaceuticals, Inc. has decided to terminate the agreement with Inex Pharmaceuticals for the development and commercialization of Inex's proprietary oncology product, Marqibo (vincristine sulfate liposomes injection).

After a careful evaluation, Enzon determined it would not support further development of Marqibo. In January 2005, the United States Food and Drug Administration (FDA) provided an action letter detailing Marqibo is "not approvable" under the FDA's accelerated approval regulations for relapsed aggressive non-Hodgkin's lymphoma.

The FDA's response also stated additional randomized controlled studies would need to be conducted prior to re-applying for approval. After a strategic analysis of the FDA's recommendation, required investment, development timeframe, and associated development risks, the Company concluded it would be in its best interest to redirect this investment to pursue other opportunities, the release states.

Enzon expects to pay Inex $5 million for certain contractual obligations, including development expenses and milestone payments.

Enzon Pharmaceuticals has developed or acquired a number of marketed products, including Peg-Intron, marketed by Schering-Plough, and Abelcet, Oncaspar, Adagen, and Depocyt, marketed in North America by Enzon's specialized sales force.