content: 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): September 1, 2004
                                                          -----------------
  
                                 CYTOGEN CORPORATION
           --------------------------------------------------------------
                 (Exact Name of Registrant as Specified in Charter)
  
           Delaware                       000-14879                 22-2322400
  ----------------------------     ------------------------    -------------------
  (State or Other Jurisdiction     (Commission File Number)      (I.R.S. Employer
       of Incorporation)                                       Identification No.)
  
   650 College Road East, CN 5308, Suite 3100, Princeton, NJ            08540
  --------------------------------------------------------------    --------------
                     (Address of Principal Executive Offices)         (Zip Code)
  
         Registrant's telephone number, including area code: (609) 750-8200
                                                             --------------
  
  --------------------------------------------------------------------------------
           (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 (see General Instruction A.2. below):
  
       |_| Written  communications  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  communications  pursuant to  Rule 14d-2(b)  under the
  Exchange Act (17 CFR 240.14d-2(b))
  
       |_| Pre-commencement  communications  pursuant to  Rule 13e-4(c)  under the
  Exchange Act (17 CFR 240.13e-4(c))
  
  <PAGE>
  
  ITEM 3.03  MATERIAL MODIFICATION TO RIGHTS OF SECURITY HOLDERS.
  
       Effective  September  1, 2004,  American  Stock  Transfer  & Trust  Company
  ("AST"),  located at 59 Maiden Lane, Plaza Level, New York, NY 10038,  telephone
  number (718) 921-8200, was appointed as the new registrar and transfer agent for
  Cytogen  Corporation  (the "Company"),  replacing  Mellon Investor  Services LLC
  ("Mellon").
  
       In connection with the Company's engagement of AST, the Company executed an
  Agreement for  Substitution and Amendment of Rights Agreement with AST, dated as
  of September 1, 2004 (the  "Substitution  Agreement"),  pursuant to which, among
  other  things,  AST shall  replace  Mellon as rights  agent under the  Company's
  Rights Agreement, as amended to date.
  
       The full text of the  Substitution  Agreement is attached hereto as Exhibit
  4.1 to this Current Report on Form 8-K and is incorporated  herein by reference.
  The  foregoing  description  of the  Substitution  Agreement is qualified in its
  entirety by reference to such Exhibit.
  
  ITEM 9.01  FINANCIAL STATEMENTS AND EXHIBITS
  
  (c)  Exhibits.
  
       Exhibit No.       Description
       -----------       -----------
  
          4.1            Agreement   for  Substitution  and  Amendment  of  Rights
                         Agreement by and between the Company and  American  Stock
                         Transfer & Trust Company dated as of September 1, 2004.
  
  
  
  <PAGE>
  
                                     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.
  
                                                  CYTOGEN CORPORATION
  
  
  
                                                  By: /s/ Michael D. Becker
                                                     -----------------------------
                                                     Michael D. Becker
                                                     President and Chief Executive
                                                     Officer
  
  Dated:   September 2, 2004
  
  
  
  <PAGE>
  
  
                                    EXHIBIT INDEX
  
  
         Exhibit No.       Description
         -----------       -----------
             4.1           Agreement for  Substitution  and  Amendment  of  Rights
                           Agreement by and between the Company and American Stock
                           Transfer & Trust Company dated as of September 1, 2004.
metadata_documents: [{"type": "8-K", "sequence": "1", "filename": "form8-k_090104.txt", "description": "FORM 8-K 09/01/04", "secsgml_size_bytes": 4783}]
metadata_filer: {"company-data": {"conformed-name": "CYTOGEN CORP", "cik": "0000725058", "assigned-sic": "2834", "irs-number": "222322400", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-14879", "film-number": "041012707"}, "business-address": {"street1": "650 COLLEGE RD EAST STE 3100", "city": "PRINCETON", "state": "NJ", "zip": "08540", "phone": "6099878200"}, "mail-address": {"street1": "650 COLLEGE RD EAST STE 3100", "city": "PRINCETON", "state": "NJ", "zip": "08540"}}
text: 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): September 1, 2004
                                                          -----------------
  
                                 CYTOGEN CORPORATION
           --------------------------------------------------------------
                 (Exact Name of Registrant as Specified in Charter)
  
           Delaware                       000-14879                 22-2322400
  ----------------------------     ------------------------    -------------------
  (State or Other Jurisdiction     (Commission File Number)      (I.R.S. Employer
       of Incorporation)                                       Identification No.)
  
   650 College Road East, CN 5308, Suite 3100, Princeton, NJ            08540
  --------------------------------------------------------------    --------------
                     (Address of Principal Executive Offices)         (Zip Code)
  
         Registrant's telephone number, including area code: (609) 750-8200
                                                             --------------
  
  --------------------------------------------------------------------------------
           (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 (see General Instruction A.2. below):
  
       |_| Written  communications  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  communications  pursuant to  Rule 14d-2(b)  under the
  Exchange Act (17 CFR 240.14d-2(b))
  
       |_| Pre-commencement  communications  pursuant to  Rule 13e-4(c)  under the
  Exchange Act (17 CFR 240.13e-4(c))
  ITEM 3.03  MATERIAL MODIFICATION TO RIGHTS OF SECURITY HOLDERS.
  
       Effective  September  1, 2004,  American  Stock  Transfer  & Trust  Company
  ("AST"),  located at 59 Maiden Lane, Plaza Level, New York, NY 10038,  telephone
  number (718) 921-8200, was appointed as the new registrar and transfer agent for
  Cytogen  Corporation  (the "Company"),  replacing  Mellon Investor  Services LLC
  ("Mellon").
  
       In connection with the Company's engagement of AST, the Company executed an
  Agreement for  Substitution and Amendment of Rights Agreement with AST, dated as
  of September 1, 2004 (the  "Substitution  Agreement"),  pursuant to which, among
  other  things,  AST shall  replace  Mellon as rights  agent under the  Company's
  Rights Agreement, as amended to date.
  
       The full text of the  Substitution  Agreement is attached hereto as Exhibit
  4.1 to this Current Report on Form 8-K and is incorporated  herein by reference.
  The  foregoing  description  of the  Substitution  Agreement is qualified in its
  entirety by reference to such Exhibit.
  
  ITEM 9.01  FINANCIAL STATEMENTS AND EXHIBITS
  
  (c)  Exhibits.
  
       Exhibit No.       Description
       -----------       -----------
  
          4.1            Agreement   for  Substitution  and  Amendment  of  Rights
                         Agreement by and between the Company and  American  Stock
                         Transfer & Trust Company dated as of September 1, 2004.
  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.
  
                                                  CYTOGEN CORPORATION
  
                                                  By: /s/ Michael D. Becker
                                                     -----------------------------
                                                     Michael D. Becker
                                                     President and Chief Executive
                                                     Officer
  
  Dated:   September 2, 2004
  EXHIBIT INDEX
  
         Exhibit No.       Description
         -----------       -----------
             4.1           Agreement for  Substitution  and  Amendment  of  Rights
                           Agreement by and between the Company and American Stock
                           Transfer & Trust Company dated as of September 1, 2004.