UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                   -----------

                                    FORM 8-K

                                 CURRENT REPORT
                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934



Date of Report (Date of earliest event reported)               October 28, 2005
- --------------------------------------------------------------------------------



                           ENZON PHARMACEUTICALS, INC.
- --------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)



   Delaware                           0-12957                 22-2372868
- --------------------------------------------------------------------------------
(State or other jurisdiction    (Commission File No.)   (IRS Identification No.)
of incorporation)


        685 Route 202/206, Bridgewater, New Jersey           08807
- --------------------------------------------------------------------------------
        (Address of principal executive offices)            (Zip Code)



Registrant's telephone number, including area code               (908) 541-8600
- --------------------------------------------------------------------------------



- --------------------------------------------------------------------------------
(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:

[_]  Written communication pursuant to Rule 425 under the Securities Act (17
     CFR 230.425)

[_]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
     240.14a-12)

[_]  Pre-commencement communication pursuant to Rule 14d-2(b) under the Exchange
     Act (17 CFR 240.14d-2(b)

[_]  Pre-commencement communication pursuant to Rule 13e-4(c) under the Exchange
     Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement - --------------------------------------------------------- On October 28, 2005, we amended our agreement with members of the sanofi-aventis Group for our oncology product, ONCASPAR(R) (pegaspargase). The amendment, which will become effective in January 2006, includes a significant reduction in the royalty rate, with a single digit royalty percentage now payable by Enzon only on those annual sales of ONCASPAR that are in excess of $25 million. Previously, we were obligated to pay a 25% royalty on all sales of ONCASPAR in the U.S. and Canada. In January 2006, we will pay an upfront cash payment of $35 million. We are required to continue making royalty payments through June 30, 2014, at which time all of our royalty obligations will cease. On October 31, 2005, we issued a press release announcing the amendment to the agreement that is attached to this current report as Exhibit 99.1. Item 9.01. Financial Statements and Exhibits. (c) Exhibits. Exhibit No. Description 99.1 Press Release dated October 31, 2005

SIGNATURES ---------- Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Dated: October 28, 2005 By: /s/ Craig A. Tooman ------------------- Craig A. Tooman Executive Vice President, Finance and Chief Financial Officer

                                                                    Exhibit 99.1

    Enzon Announces Amendment to ONCASPAR Agreement with Members of
                       the Sanofi-Aventis Group

    Reduced Royalty Obligation Provides Enzon with Increased Profit
                              Ownership

   BRIDGEWATER, N.J.--(BUSINESS WIRE)--Oct. 31, 2005--Enzon
Pharmaceuticals, Inc. (NASDAQ: ENZN) today announced that it has
amended its license agreement with members of the sanofi-aventis Group
(NYSE: SNY; EURONEXT: SAN) for the Company's oncology product,
ONCASPAR(R) (pegaspargase). The amendment, which will become effective
in January 2006, includes a significant reduction in the royalty rate,
with a single digit royalty percentage now payable by Enzon only on
those annual sales of ONCASPAR that exceed a certain predetermined
level. Previously, Enzon was obligated to pay a 25% royalty on all
sales of ONCASPAR in the U.S. and Canada.
   "Today's announcement further underscores our commitment to drive
future growth by investing in our marketed brands," said Jeffrey H.
Buchalter, Enzon's chairman and chief executive officer. "Since its
approval, ONCASPAR has offered a significant clinical advantage to
leukemia patients who are hypersensitive to native L-asparaginase. We
believe there is a strong growth opportunity for ONCASPAR beyond its
currently approved indication and we are committed to making the
appropriate investments to optimize that potential."
   While specific financial terms are not being disclosed, under the
amended agreement, Enzon will pay a single digit royalty percentage on
annual sales of ONCASPAR that are in excess of $25 million. Enzon will
make an upfront cash payment of $35 million. Enzon is obligated to
make royalty payments through June 30, 2014, at which time all of its
royalty obligations will cease.

   About ONCASPAR

   ONCASPAR is a PEG-enhanced version of the naturally occurring
enzyme L-asparaginase. L-asparaginase is an enzyme that depletes the
amino acid asparagine, which certain leukemic cells are dependent upon
for survival. Enzon developed ONCASPAR and obtained a marketing
license by the U.S. Food and Drug Administration in February 1994 for
the treatment of patients with acute lymphoblastic leukemia who
require L-asparaginase in their treatment regimen, but have developed
hypersensitivity to native forms of L-asparaginase. Through its
proprietary PEGylation technology, Enzon designed ONCASPAR to offer
therapeutic advantages over unmodified L-asparaginase. In addition to
reduced immunogenicity, ONCASPAR provides a more convenient,
patient-friendly dosing regimen that allows for administration every
14 days, versus twice weekly for unmodified L-asparaginase. Enzon's
specialized oncology sales force currently markets ONCASPAR in North
America. Enzon reported $21.2 million in net sales of ONCASPAR for the
year ended June 30, 2005, as compared to $18.1 million for the year
ended June 30, 2004.
   About 35,000 new cases of leukemia will be diagnosed in the United
States during 2005. Of these about 4,000 will be acute lymphoblastic
leukemia (also called acute lymphocytic leukemia or ALL). Although ALL
is mainly a childhood leukemia, about one-third of new cases will
occur in adults.

   About Enzon

   Enzon Pharmaceuticals, Inc. is a biopharmaceutical company
dedicated to the development and commercialization of therapeutics to
treat 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 also
receives royalties on sales of PEG-INTRON(R), marketed by
Schering-Plough Corporation, and MACUGEN(R), marketed by Eyetech
Pharmaceuticals and Pfizer Inc. Enzon's product-driven strategy
includes an extensive drug development program that leverages its
proprietary technologies, including a next-generation PEGylation
platform that utilizes linkers designed to release compounds at a
controlled rate. Enzon complements its internal research and
development efforts with strategic initiatives, such as partnerships
designed to broaden its revenue base or provide access to promising
new technologies or product development opportunities. Further
information about Enzon can be found on the Company's web site 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," "estimate,"
"continue," "anticipates," "intends," "expects," and similar
expressions. Such forward-looking statements involve known and unknown
risks, uncertainties and other factors, including those discussed in
our most recent annual report on Form 10-K on file with the U.S.
Securities and Exchange Commission, that may cause actual results,
events or developments to be materially different from the future
results, events or developments discussed above. All information in
this press release is as of October 31, 2005 and the Company
undertakes no duty to update this information.

    CONTACT: Enzon Pharmaceuticals, Inc.
             Susan Mesco, 908-541-8678