Another LNA-based RNA Inhibitor Enters Clinical Trials

COPENHAGEN - EZN3042 - a Survivin Inhibitor Jointly Developed by Enzon
Pharmaceuticals and Santaris Pharma Advances into the Clinic for Patients
With Solid Tumors and Lymphomas

Santaris Pharma announced today that the fourth LNA-based drug
has been brought into the clinic. In the USA several patients with cancer
have now been treated with the Company’s Survivin inhibitor, which is jointly
developed by Santaris Pharma and Enzon Pharmaceuticals. The U.S. Food and
Drug Administration (FDA) recently accepted Enzon Pharma­ceutical’s
Investigational New Drug (IND) application for the use of the LNA-based
Survivin inhibitor.

Survivin is a key protein that controls cancer growth by playing a
significant role in cell division, as well as inhibiting the programming that
controls cell death. The Survivin inhibitor was developed using the Locked
Nucleic Acid technology. In preclinical animal studies, EZN-3042 inhibited
Survivin expression and tumor growth. It also potentiated the antitumor
activity of taxol, an approved cancer therapeutic.

“Survivin is considered one of the most promising cancer targets and we
are pleased that we were able to quickly advance this important compound into
patients,” said Jeffrey H. Buchalter, chairman and chief executive officer of
Enzon Pharmaceuticals.

EZN3042 is one of eight LNA-based RNA inhibitors being
developed by Santaris Pharma and Enzon Pharmaceuticals through a
comprehensive partnership within the therapeutic area of cancer. Another
compound forming part of the collaboration, EZN2968, an LNA-based hif1alfa
inhibitor, is currently being investigated in two Phase I/II trials against a
variety of cancers. Under the terms of the agreement, Enzon will have
exclusive rights to develop and commercialize these compounds in the U.S. and
other non-European territories. Santaris Pharma will retain exclusive rights
to commercialization in Europe.

“This is the fourth LNA-based drug that has been brought into the clinic
in record time either by ourselves or by a partner of ours based on our
highly effective Drug Discovery Engine,” said Henrik 0rum, CSO at Santaris
Pharma. “We are very pleased by the achievement of this milestone and look
forward to seeing other new LNA-based compounds advance into clinical trials
across a range of therapeutic areas in the near future.”

At the Association for Cancer Research (AACR) meeting being held April
18-22, 2009 in Colorado, Enzon Pharmaceuticals will present data on EZN3042
as well as on new LNA targets. Abstracts related to those targets are now
available on www.aacr.org.

“Novel releasable PEG-nanoparticles enhance delivery of RNA antagonist
oligonucleotides in tumor cells and in mice”

“EZN-2208, a novel pegylated SN-38 drug conjugate, markedly inhibits
tumor growth and metastatic spreading of human neuroblastoma”

“Androgen receptor (AR) down regulation by locked nucleic acid antisense
oligonucleotides specifically inhibits the growth of AR-positive tumor cells”

“The antitumor activity of EZN-4150, a potent LNA-based PIK3CA
antagonist”

“EZN-3042, a novel locked nucleic acid oligonucleotide against survivin,
inhibits survivin expression and confers taxol sensitivity”

“EZN-3920, an LNA antisense oligonucleotide RNA antagonist, down
modulates HER3 expression and PI3K/Akt signaling pathway and enhances
antiproliferative effect of Gefitinib in tumor cells”

www.santaris.com

About Santaris Pharma

Santaris Pharma is a privately held biopharmaceutical company
with exclusive rights to use the LNA Drug Platform to develop new classes of
RNA medicines targeting mRNAs and miRNAs associated with disease. The
Company’s own research and development activities focus on microRNAs,
infectious diseases and metabolic disorders. In addition, Santaris Pharma is
leveraging its highly effective and efficient drug discovery engine to
generate lead LNA drug candidates against a broad array of disease targets
selected by strategic partners. Santaris Pharma was founded in 2003 and the
Company and its corporate partners currently have four compounds in clinical
development and a full pipeline in late preclinical development. Current
partners are Enzon Pharmaceuticals, GlaxoSmithKline and Wyeth
Pharmaceuticals. Santaris Pharma has since its inception raised nearly $100
million through private financing and up front payments.

About Enzon

Enzon Pharmaceuticals, Inc. is a biopharmaceutical company dedicated to
developing, manufacturing and commercializing important medicines for
patients with cancer and other life-threatening conditions. The Company has
a portfolio of four marketed products, Oncaspar(R), DepoCyt(R), Abelcet(R)
and Adagen(R). Enzon’s drug development programs utilize several
cutting-edge approaches, including its industry-leading PEGylation
technology platform and the Locked Nucleic Acid (LNA) technology. Enzon’s
PEGylation technology was used to develop two of its products, Oncaspar and
Adagen, and has created a royalty revenue stream from licensing
partner-ships for other products developed using the technology. Enzon
also engages in contract manufacturing for several pharmaceutical companies
to broaden the Company’s revenue base.

Source: Santaris Pharma A/S

Contact: Randi Krogsgaard, Director, Corporate Communications, Direct phone +45-4517-9879, Cell: +45-20488384, E-mail: rmk at santaris.com