UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
                    Under the Securities Exchange Act of 1934

                               Cytogen Corporation
                          n/k/a EUSA Pharma (USA), Inc.
                                (Name of Issuer)

--------------------------------------------------------------------------------

                     Common Stock, $0.01 Par Value Per Share
                         (Title of Class of Securities)

================================================================================

                                    232824300
                                 (CUSIP Number)

--------------------------------------------------------------------------------

                           Zoe Evans, General Counsel
                                EUSA Pharma Inc.
                               The Magdalen Center
                               Oxford Science Park
                                   Oxford, UK
                                     OX4-4GA
                               44 (1) 1865 784255

                                 With a copy to
                             Jeffrey A. Baumel, Esq.
                        Sonnenschein Nath & Rosenthal LLP
                                 101 JFK Parkway
                              Short Hills, NJ 07078
                                  973-912-7100
           (Name, Address and Telephone Number of Person Authorized to
                       Receive Notices and Communications)

================================================================================

                                   May 8, 2008
             (Date of Event which Requires Filing of this Statement)

--------------------------------------------------------------------------------

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of ss.ss.240.13d-l(e), 240.13d-l(f) or 240.13d-1(g), check the
following box. |_|

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934, as amended (the "Exchange Act") or otherwise subject to the liabilities of
that section of the Exchange Act but shall be subject to all other provisions of
the Exchange Act (however, see the Notes).



CUSIP No. 232824300
================================================================================
   1   NAMES OF REPORTING PERSONS.

       EUSA Pharma Inc.
--------------------------------------------------------------------------------
   2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP(1)               (a) |_|
                                                                         (b) |_|
       Not applicable.
--------------------------------------------------------------------------------
   3   SEC USE ONLY
--------------------------------------------------------------------------------
   4   SOURCE OF FUNDS

       OO
--------------------------------------------------------------------------------
   5   CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
       ITEMS 2(d) OR 2(e)

       |_|
--------------------------------------------------------------------------------
   6   CITIZENSHIP OR PLACE OF ORGANIZATION

       Delaware
--------------------------------------------------------------------------------
  NUMBER OF      7   SOLE VOTING POWER
   SHARES
BENEFICIALLY         36,093,873
  OWNED BY    ------------------------------------------------------------------
    EACH         8   SHARED VOTING POWER
  REPORTING
 PERSON WITH         -0-
              ------------------------------------------------------------------
                 9   SOLE DISPOSITIVE POWER

                     36,093,873
              ------------------------------------------------------------------
                10   SHARED DISPOSITIVE POWER

                     -0-
--------------------------------------------------------------------------------
  11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

       36,093,873 See footnote (1)
--------------------------------------------------------------------------------
       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
  12
       |_|
--------------------------------------------------------------------------------
  13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

       100%
--------------------------------------------------------------------------------
  14   TYPE OF REPORTING PERSON

       CO
================================================================================

(1) As more fully described herein, on May 8, 2008, EUSA Pharma Inc. ("EUSA")
consummated the acquisition of Cytogen Corporation (the "Corporation") through
the merger of EUSA Pharma (USA), Inc., a wholly-owned subsidiary of EUSA
("Merger Sub"), into the Corporation.



CUSIP No. 232824300
================================================================================
   1   NAMES OF REPORTING PERSONS.

       EUSA Pharma (USA), Inc.
--------------------------------------------------------------------------------
   2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP(1)               (a) |_|
                                                                         (b) |_|
       Not applicable.
--------------------------------------------------------------------------------
   3   SEC USE ONLY
--------------------------------------------------------------------------------
   4   SOURCE OF FUNDS(1)

       Not applicable.
--------------------------------------------------------------------------------
   5   CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
       ITEMS 2(d) OR 2(e)

       |_|
--------------------------------------------------------------------------------
   6   CITIZENSHIP OR PLACE OF ORGANIZATION

       Delaware
--------------------------------------------------------------------------------
  NUMBER OF      7   SOLE VOTING POWER
   SHARES
BENEFICIALLY         -0-
  OWNED BY    ------------------------------------------------------------------
    EACH         8   SHARED VOTING POWER
  REPORTING
 PERSON WITH         -0-
              ------------------------------------------------------------------
                 9   SOLE DISPOSITIVE POWER

                     -0-
              ------------------------------------------------------------------
                10   SHARED DISPOSITIVE POWER

                     -0-
--------------------------------------------------------------------------------
  11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

       -0- See footnote (1)
--------------------------------------------------------------------------------
       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
  12
       |_|
--------------------------------------------------------------------------------
  13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

       Not applicable.
--------------------------------------------------------------------------------
  14   TYPE OF REPORTING PERSON

       CO
================================================================================

(1) As more fully described herein, on May 8, 2008, EUSA consummated the
acquisition of the Corporation through the merger of Merger Sub into the
Corporation.



                             INTRODUCTORY STATEMENT

      As more fully described under Items 4 and 6 herein, on March 10, 2008,
EUSA Pharma Inc., a Delaware corporation ("EUSA"), and its wholly-owned
subsidiary, EUSA Pharma (USA), Inc., also a Delaware corporation ("Merger Sub"),
entered into a definitive Agreement and Plan of Merger (the "Merger Agreement")
with Cytogen Corporation (the "Corporation") pursuant to which EUSA would
acquire the Corporation through the merger (the "Merger") of Merger Sub into the
Corporation.

Item 1. Security and Issuer

      The securities to which this Statement on Schedule 13D relates are shares
of the common stock, $0.01 par value per share (the "Common Stock"), of the
Corporation. The principal executive offices of the Corporation are located at
650 College Road East, Suite 3100, Princeton, New Jersey 08540.

Item 2. Identity and Background

      This Statement on Schedule 13D is filed by EUSA and its wholly-owned
subsidiary, Merger Sub. EUSA is a specialty pharmaceutical company with a
portfolio of pharmaceutical products focused on oncology, pain control and
critical care. The principal business and offices of each of EUSA and Merger Sub
in the United States are located at Heritage Gateway Centre, 1980 S. Easton
Road, Suite 250, Doylestown, PA 18901. The names, citizenship, business or
residence address and principal occupation of each executive officer and
director of EUSA and Merger Sub is set forth in Annex 1 attached hereto, which
information is incorporated herein by reference.

      During the last five years neither EUSA, Merger Sub, nor, to the best of
the knowledge of EUSA and Merger Sub, any executive officer or director of EUSA
or Merger Sub identified on Annex 1 has (a) been convicted in a criminal
proceeding (excluding traffic violations and similar misdemeanors) or (b) been a
party to a civil proceeding of a judicial or administrative body of competent
jurisdiction, and as a result of such proceeding was or is subject to a
judgment, decree or a final order enjoining future violations or, or prohibiting
or mandating activities subject to federal or state securities laws or finding
any violations with respect to such laws.

Item 3. Source and Amount of Funds or Other Consideration

      The acquisition of an aggregate of 36,093,873 shares of the Common Stock
was consummated on May 8, 2008 through the Merger of Merger Sub into the
Corporation pursuant to which each share of Common Stock issued and outstanding
immediately prior to the effective time of the Merger has been cancelled and
converted into the right to receive $0.62 in cash (without interest). On the
basis of the 36,093,873 shares of Common Stock issued and outstanding
immediately prior to the effective time and the amount payable to holders of
derivative securities as described under Item 4 below, the aggregate purchase
price in the Merger is $22,403,361. In order to finance the consideration for
the acquisition and provide working capital, EUSA raised over $50 million in an
investment financing. This financing was led by TVM Capital and supported by
EUSA's existing investors, Essex Woodlands, 3i, Goldman Sachs, Advent Venture
Partners, SV Life Sciences, NeoMed and NovaQuest.

Item 4. Purpose of Transaction

      On May 8, 2008 (the "Closing"), EUSA consummated the acquisition of the
Corporation, in accordance with the provisions of an Agreement and Plan of
Merger, dated as of March 10, 2008, among EUSA, Merger Sub and the Corporation
pursuant to which Merger Sub merged with and into the Corporation. The
Corporation continues as the surviving entity and a wholly-owned subsidiary of
EUSA. By virtue of the Merger, each share of Common Stock issued and outstanding
immediately prior to the effective time of the Merger has been cancelled and
converted into the right to receive $0.62 in cash (without interest).
Immediately prior to the Closing, each outstanding option, stock equivalent
right, warrant or other right to acquire shares of Common Stock became fully
exercisable and vested and was cancelled and converted into the right to



receive, in consideration of such cancellation, a cash payment equal to the
product of (a) the excess of $0.62 over the exercise price of such derivative
security, if any, and (b) the number of shares of Common Stock subject thereto
which amounted to $25,160. Also pursuant to the Merger Agreement, at the Closing
the Corporation delivered to EUSA the resignation of each director of the
Corporation and each of its subsidiaries.

      The Merger Agreement and the Merger were approved by the holders of more
than a majority of the outstanding shares of Common Stock. In connection with
the solicitation of votes in favor of the Merger, the Corporation filed with the
Securities and Exchange Commission a preliminary proxy statement which was
distributed to the Corporation's stockholders subsequently in definitive form
containing the information required of the Corporation under Schedule 14A
promulgated by the Commission. As a consequence of the consummation of the
Merger, the Common Stock has ceased to be publicly traded and is eligible for
termination of registration under the Exchange Act.

      EUSA does not have any plans or proposals which relate to or would result
in any other action specified in clauses (a) through (j) of Item 4 of Schedule
13D.

      Reference is made to the full text of the Merger Agreement which is filed
as Exhibit B hereto . Such text is hereby incorporated by reference in this
Statement and qualifies all matters set forth herein.

Item 5. Interest in Securities of the Issuer

      (a) Prior to the consummation of the Merger and excluding the effect of
the Merger Agreement which, prior to the approval of the Corporation's
stockholders to the Merger, was conditioned on such approval which was beyond
the parties' control, neither EUSA nor Merger Sub beneficially owned, for
purposes of Rule 13d-3 under the Exchange Act, any shares of Common Stock, and,
during the sixty days prior to the date of the Merger Agreement, neither EUSA
nor Merger Sub effected any transactions in the Common Stock. As disclosed by
such persons to EUSA and Merger Sub, as of May 7, 2008, except as set forth on
Annex 1, none of the executive officers or directors of either EUSA or Merger
Sub beneficially owned any shares of Common Stock nor, except as set forth on
Annex 1, during the sixty days prior to the date of the Merger Agreement, did
any such executive officer or director effect any transactions in the Common
Stock.

      As of May 8, 2008, EUSA beneficially owns, for purposes of Rule 13d-3
under the Exchange Act, 36,093,873 shares of Common Stock, constituting 100% of
the issued and outstanding shares of Common Stock. All of such shares are
beneficially owned by EUSA.

      (b) All of the shares of Common Stock beneficially owned by EUSA are held
with sole power to vote or to direct the vote thereof and with sole power to
dispose or to direct the disposition thereof.

      (c) At the effective time of the Merger, as more fully described under
Item 4 herein, EUSA consummated the Merger. As a result of the consummation of
the Merger, 36,093,873 shares of Common Stock were cancelled and converted into
the right to receive $0.62 per share in cash (without interest). Immediately
prior to the Closing, each outstanding option, stock equivalent right, warrant
or other right to acquire shares of Common Stock became fully exercisable and
vested and was cancelled and converted into the right to receive, in
consideration of such cancellation, a cash payment equal to the product of (a)
the excess of $0.62 over the exercise price of such derivative security, if any,
and (b) the number of shares of Common Stock subject thereto which amounted to
$25,160.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to
Securities of the Issuer

      As more fully described under Item 4 above, on May 8, 2008, EUSA and
Merger Sub consummated the acquisition of the Corporation by merger of Merger
Sub with and into the Corporation pursuant to the previously executed Merger
Agreement. Contemporaneously with the execution and delivery of the Merger
Agreement, each of the officers and directors and J.P. Morgan Ventures



Corporation, the holder of approximately 13% of the Common Stock, entered into
voting agreements with the Corporation and EUSA pursuant to which such parties,
among other things, agreed to vote their respective shares of Common Stock in
favor of the adoption of the Merger Agreement and the transactions contemplated
thereby, in favor of the adoption of any proposal or action that is reasonably
determined by the Corporation to be necessary or appropriate to submit for
stockholder approval in order to facilitate the consummation of the transactions
contemplated by the Merger Agreement and against any competing proposal.

      Reference is made to the full text of the form of voting agreement which
is filed as Exhibit C hereto. Such text is hereby incorporated by reference in
this Statement and qualifies all matters set forth herein.

      Except for the Merger Agreement and the voting agreement, neither EUSA nor
Merger Sub nor, to the best of the knowledge of EUSA and Merger Sub, any of the
executive officers or directors listed in Annex 1, is a party to any contract,
arrangement, understanding or relationship (legal or otherwise) with any person
with respect to any securities of the Corporation, including, but not limited
to, the transfer or voting of such securities, finder's fees, joint ventures,
loan or option arrangements, puts or calls, guaranties of profits, divisions of
profit or loss or the giving or withholding of proxies.

Item 7. Material to Be Filed as Exhibits

--------------------------------------------------------------------------------
     Exhibit Reference                            Exhibit
--------------------------------------------------------------------------------
         Exhibit A         Agreement pursuant to Rule 13d-1(k)(1)(iii)
--------------------------------------------------------------------------------
         Exhibit B         Agreement and Plan of Merger, dated as of March 10,
                           2008, among EUSA, Merger Sub and the Corporation
--------------------------------------------------------------------------------
         Exhibit C         Form of Voting Agreement, dated as of March 10, 2008,
                           entered into by EUSA, the Corporation and each of the
                           Corporation's officers and Directors and J.P. Morgan
                           Ventures Corporation, a stockholder of the
                           Corporation
--------------------------------------------------------------------------------



                                    SIGNATURE

      After reasonable inquiry and to the best of my knowledge and belief, we
certify that the information set forth in this statement is true, complete and
correct.

Date: May 8, 2008


EUSA PHARMA INC.                        EUSA PHARMA (USA), INC.


By: /s/ Zoe Evans                       By: /s/ Zoe Evans
    --------------------------------        --------------------------------
Name:  Zoe Evans                        Name:  Zoe Evans
Title: General Counsel                  Title: General Counsel



                                     Annex 1



----------------------------------------------------------------------------------------------------------
Name and Business or         Citizenship               Position with EUSA       Principal Occupation,
Residence Address*                                     Pharma Inc.              Employer and Address of
                                                                                Employer*
----------------------------------------------------------------------------------------------------------
                                                                       
Rolf Stahel                  Swiss                     Non-Executive Chairman

The Magdalen Centre
Oxford Science Park
Oxford OX4 4GA
UK
----------------------------------------------------------------------------------------------------------
Bryan Morton                 British                   President and Chief      President and Chief
                                                       Executive Officer and    Executive Officer of EUSA
The Magdalen Centre                                    Director
Oxford Science Park                                                             The Magdalen Centre
Oxford OX4 4GA                                                                  Oxford Science Park
UK                                                                              Oxford OX4 4GA
                                                                                UK
----------------------------------------------------------------------------------------------------------
Petri Vainio                 Finnish                   Director                 Essex Woodlands

Berkley Square House                                                            Berkley Square House
Berkley Square                                                                  Berkley Square
London, W1J 6BD                                                                 London, W1J 6BD
UK                                                                              UK
----------------------------------------------------------------------------------------------------------
William Crouse               U.S.                      Director
----------------------------------------------------------------------------------------------------------
Goran Ando                   Swedish                   Director                 Essex Woodland

Berkley Square House                                                            Berkley Square House
Berkley Square                                                                  Berkley Square
London, W1J 6BD                                                                 London, W1J 6BD
UK                                                                              UK
----------------------------------------------------------------------------------------------------------
Gilles Alberici              French                    Director                 The Magdalen Centre
                                                                                Oxford Science Park
The Magdalen Centre                                                             Oxford OX4 4GA
Oxford Science Park                                                             UK
Oxford OX4 4GA
UK
----------------------------------------------------------------------------------------------------------
Andrew Fraser                British                   Director                 3i plc

16 Palace Street                                                                16 Palace Street
London SW1E 5JD                                                                 London SW1E 5JD
UK                                                                              UK
----------------------------------------------------------------------------------------------------------
Raj Parekh                   British                   Director                 Advent Venture Partners

25 Buckingham Gate                                                              25 Buckingham Gate
London SW1E 6LD                                                                 London SW1E 6LD
UK                                                                              UK
----------------------------------------------------------------------------------------------------------
Zoe Evans                    British                   General Counsel and      General Counsel and
                                                       Secretary                Secretary of EUSA
The Magdalen Centre
Oxford Science Park
Oxford OX4 4GA
UK
----------------------------------------------------------------------------------------------------------


      *Unless otherwise indicated the business address of the individuals
identified is the address of EUSA.





----------------------------------------------------------------------------------------------------------
Name and Business or        Citizenship               Position with EUSA        Principal Occupation,
Residence Address*                                    Pharma (USA), Inc.        Employer and Address of
                                                                                Employer*
----------------------------------------------------------------------------------------------------------
                                                                       
Bryan Morton                British                   Director and President    President of EUSA Pharma
                                                                                (USA), Inc.
The Magdalen Centre
Oxford Science Park
Oxford OX4 4GA
UK
----------------------------------------------------------------------------------------------------------
David Cook                  British                   Director and Treasurer    Treasurer of EUSA Pharma
                                                                                (USA), Inc.
The Magdalen Centre
Oxford Science Park
Oxford OX4 4GA
UK
----------------------------------------------------------------------------------------------------------
Zoe Evans                   British                   Corporate Secretary       Corporate Secretary of
                                                                                EUSA Pharma (USA), Inc.
The Magdalen Centre
Oxford Science Park
Oxford OX4 4GA
UK
----------------------------------------------------------------------------------------------------------


      *Unless otherwise indicated the business address of the individuals
identified is the address of EUSA.



                                INDEX TO EXHIBITS

--------------------------------------------------------------------------------
     Exhibit Reference                            Exhibit
--------------------------------------------------------------------------------
         Exhibit A         Agreement pursuant to Rule 13d-1(k)(1)(iii)
--------------------------------------------------------------------------------
         Exhibit B         Agreement and Plan of Merger, dated as of March 10,
                           2008, among EUSA, Merger Sub and the Corporation
--------------------------------------------------------------------------------
         Exhibit C         Form of Voting Agreement, dated as of March 10, 2008,
                           entered into by EUSA, the Corporation and each of the
                           Corporation's officers and Directors and J.P. Morgan
                           Ventures Corporation, a stockholder of the
                           Corporation
--------------------------------------------------------------------------------