UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549


                                  SCHEDULE 13G


                 UNDER THE SECURITIES EXCHANGE ACT OF 1934(1)


                                  CYTOGEN CORP.
                                (Name of Issuer)

                          COMMON STOCK, $.01 PAR VALUE
                         (Title of Class of Securities)

                                   232824 30 0
                                 (CUSIP Number)

                                 AUGUST 2, 2005
           (Date of Event Which Requires Filing of this Statement)


                Check the appropriate box to designate the rule
                   pursuant to which this Schedule is filed:

                                |_| Rule 13d-1(b)
                
                                |X| Rule 13d-1(c)
                
                                |_| Rule 13d-1(d)

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

     (1) The  remainder  of this cover page shall be filled out for a  reporting
person's  initial  filing on this  form with  respect  to the  subject  class of
securities,  and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.

     The  information  required in 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 or otherwise  subject to the  liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  SEE the
NOTES).

                                       1


CUSIP No. 232824 30 0                   13G                   Page 2 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     ProQuest Investments II, L.P.    22-3764772

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               426,086
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               426,086
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     426,086
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     2.3%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     PN
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       2


CUSIP No. 232824 30 0                   13G                   Page 3 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     ProQuest Investments III, L.P.    20-0992411

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               1,090,850
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               1,090,850
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     1,090,850
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     5.8%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     PN
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       3


CUSIP No. 232824 30 0                   13G                   Page 4 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     ProQuest Investments II Advisors Fund, L.P.    22-3784567

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               10,254
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               10,254
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     10,254
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     0.1%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     PN
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       4


CUSIP No. 232824 30 0                   13G                   Page 5 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     ProQuest Associates II LLC    22-3764735

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               436,340
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               436,340
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     436,340
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     2.3%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     OO
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       5


CUSIP No. 232824 30 0                   13G                   Page 6 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     ProQuest Associates III LLC    20-0992451

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               1,090,850
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               1,090,850
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     1,090,850
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     5.8%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     OO
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       6


CUSIP No. 232824 30 0                   13G                   Page 7 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     Jay Moorin

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Unitd States
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               1,527,190
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               1,527,190
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     1,527,190
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     8.2%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     IN
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       7


CUSIP No. 232824 30 0                   13G                   Page 8 of 14 Pages

-------------------------------------------------------------------------------
1.   NAMES OF  REPORTING  PERSONS  I.R.S.  IDENTIFICATION  NO. OF ABOVE  PERSONS
     (ENTITIES ONLY)

     Alain Schreiber

-------------------------------------------------------------------------------
2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP**                 (a) |_|
                                                                        (b) |X|

-------------------------------------------------------------------------------
3.   SEC USE ONLY

-------------------------------------------------------------------------------
4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
------------------  -----------------------------------------------------------
                            5. SOLE VOTING POWER
   NUMBER OF
                              -0-
     SHARES
                            6. SHARED VOTING POWER
  BENEFICIALLY
                               1,527,190
    OWNED BY
                            7. SOLE DISPOSITIVE POWER
      EACH
                               -0-
    REPORTING
                            8. SHARED DISPOSITIVE POWER
   PERSON WITH
                               1,527,190
------------------  -----------------------------------------------------------
9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     1,527,190
-------------------------------------------------------------------------------
10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES**   |_|


-------------------------------------------------------------------------------
11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     8.2%
-------------------------------------------------------------------------------
12.  TYPE OF REPORTING PERSON**

     IN
-------------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT


                                       8


CUSIP No. 232824 30 0                   13G                   Page 9 of 14 Pages

ITEM 1(A).  NAME OF ISSUER.

      Cytogen Corp. (the "Company").

ITEM 1(B).  ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES.

     The Company's  principal  executive offices are located at 650 College Road
East, Suite 3100, Princeton, NJ 08540-5308.

ITEMS 2(A). NAME OF PERSON FILING.

     This statement is filed on behalf of the following  persons with respect to
shares of common  stock of the  Company ( the  "Shares")  in  connection  with a
private placement of the Company's securities.

     (i)  ProQuest   Investments  II,  L.P.,  a  Delaware  limited   partnership
("Investments II"), with respect to Shares beneficially owned by it;

     (ii)  ProQuest   Investments  III,  L.P.  a  Delaware  limited  partnership
("Investments III"), with respect to Shares beneficially owned by it;

     (iii)  ProQuest  Investments  II Advisors  Fund,  L.P., a Delaware  limited
partnership ("Advisors Fund"), with respect to Shares beneficially owned by it;

     (iv)  ProQuest  Associates  II LLC, a Delaware  limited  liability  company
("Associates  II"), as General Partner of Investments II and Advisors Fund, with
respect to Shares beneficially owned by Investments II and Advisors Fund;

     (v)  ProQuest  Associates  III LLC, a Delaware  limited  liability  company
("Associates  III"),  as General  Partner of  Investments  III,  with respect to
Shares beneficially owned by Investments III;

     (vi) Jay Moorin, an individual and a member of Associates II and Associates
III  ("Moorin"),  with respect to Shares  beneficially  owned by Investments II,
Advisors Fund, and Investments III; and

     (vii) Alain  Schreiber,  an  individual  and a member of  Associates II and
Associates  III  ("Schreiber"),  with  respect to Shares  beneficially  owned by
Investments II, Advisors Fund, and Investments III.

     The foregoing  persons are  hereinafter are referred to collectively as the
"Reporting  Persons." Any disclosures  herein with respect to persons other than
the Reporting Persons are made on information and belief after making inquiry to
the appropriate party.

ITEM 2(B).  ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE.

     The  address  of the  principal  business  office of each of the  Reporting
Persons is 90 Nassau Street, 5th Floor, Princeton, NJ 08542.


                                       9


CUSIP No. 232824 30 0                   13G                  Page 10 of 14 Pages

ITEM 2(C).  CITIZENSHIP.

     Mr. Moorin is a United  States  citizen.  Mr.  Schreiber is a United States
resident alien.  Investments II, Investments III, and Advisors Fund are Delaware
limited  partnerships  organized  under  the  laws  of the  State  of  Delaware.
Associates  II and  Associates  III are  Delaware  limited  liability  companies
organized under the laws of the State of Delaware.

ITEM 2(D).  TITLE OF CLASS OF SECURITIES.

     Common stock, par value $0.01 per share.

ITEM 2(E).  CUSIP NUMBER.

     232824 30 0

ITEM 3.

     If this  statement is filed pursuant to Rules 13d-1(b) or 13d- 2(b) or (c),
check whether the person filing is a:

     (a)  |_| Broker or dealer registered under Section 15 of the Act,

     (b)  |_| Bank as defined in Section 3(a)(6) of the Act,

     (c)  |_| Insurance Company as defined in Section 3(a)(19) of the Act,

     (d)  |_| Investment  Company  registered  under Section 8 of the Investment
              Company Act of 1940,

     (e)  |_| Investment Adviser in accordance with Rule 13d-1 (b)(1)(ii)(E),

     (f)  |_| Employee  Benefit Plan or Endowment Fund in accordance  with 13d-1
              (b)(1)(ii)(F),

     (g)  |_| Parent Holding  Company or control person in accordance  with Rule
              13d-1 (b)(1)(ii)(G),

     (h)  |_|  Savings  Association  as defined in Section  3(b) of the  Federal
               Deposit Insurance Act,

     (i)  |_| Church Plan that is excluded from the  definition of an investment
              company under Section  3(c)(14) of the Investment  Company Act of
              1940,

     (j)  |_| Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

     If this statement is filed pursuant to 13d-1(c), check this box:     |X|


                                       10


CUSIP No. 232824 30 0                   13G                  Page 11 of 14 Pages

ITEM 4.     OWNERSHIP.

     The percentages  used herein are calculated  based upon  18,741,488  shares
issued and  outstanding,  as of November 10, 2005, based upon the Company's Form
10-Q for the  quarterly  period  ending  September  30, 2005. As of the close of
business on August 5, 2005, the Reporting  Persons owned shares of the Company's
common stock in the amounts and percentages listed below:

     A.   PROQUEST INVESTMENTS II, L.P.

     (a)  Amount beneficially owned: 426,086

     (b)  Percent of class: 2.3%

     (c)  (i) Sole power to vote or direct the vote: -0-

          (ii) Shared power to vote or direct the vote: 426,086

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 426,086

     B.   PROQUEST INVESTMENTS III, L.P.

     (a)  Amount beneficially owned: 1,090,850

     (b)  Percent of class: 5.8%

     (c)  (i) Sole power to vote or direct the vote: -0-

          (ii) Shared power to vote or direct the vote: 1,090,850

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 1,090,850

     C.   PROQUEST INVESTMENTS II ADVISORS FUND, L.P.

     (a)  Amount beneficially owned: 10,254

     (b)  Percent of class: 0.1%

     (c)  (i) Sole power to vote or direct the vote: -0-

          (ii) Shared power to vote or direct the vote: 10,254

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 10,254



                                       11


CUSIP No. 232824 30 0                   13G                  Page 12 of 14 Pages

     D.   PROQUEST ASSOCIATES II LLC

     (a)  Amount beneficially owned: 436,340

     (b)  Percent of class: 2.3%

     (c)  (i) Sole power to vote or direct the vote: -0-

          (ii) Shared power to vote or direct the vote: 436,340

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 436,340

     E.   PROQUEST ASSOCIATES III LLC

     (a)  Amount beneficially owned: 1,090,850

     (b)  Percent of class: 5.8%

     (c)  (i) Sole power to vote or direct the vote: -0-

          (ii) Shared power to vote or direct the vote: 1,090,850

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 1,090,850

     F.   JAY MOORIN

     (a)  Amount beneficially owned: 1,527,190

     (b)  Percent of class: 8.2%

     (c)  (i) Sole power to vote or direct the vote: -0-

          (ii) Shared power to vote or direct the vote: 1,527,190

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 1,527,190

     G.   ALAIN SCHREIBER

     (a)  Amount beneficially owned: 1,527,190

     (b)  Percent of class: 8.2%

     (c)  (i) Sole power to vote or direct the vote: -0-



                                       12


CUSIP No. 232824 30 0                   13G                  Page 13 of 14 Pages

          (ii) Shared power to vote or direct the vote: 1,527,190

          (iii) Sole power to dispose or direct the disposition: -0-

          (iv) Shared power to dispose or direct the disposition: 1,527,190

ITEM 5.     OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

     If this  statement  is being  filed to report  the fact that as of the date
hereof the reporting  person has ceased to be the beneficial  owner of more than
five percent of the class of securities, check the following. |_|

ITEM 6.     OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

     To the knowledge of the Reporting Persons, no other person has the right to
receive or the power to direct the receipt of  dividends  from,  or the proceeds
from the sale of, a number of the Shares which represents more than five percent
of the number of outstanding shares of the Shares.

ITEM 7.     IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH
            ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING
            COMPANY.

     Not Applicable.

ITEM 8.     IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

     Not Applicable.

ITEM 9.     NOTICE OF DISSOLUTION OF GROUP.

     Not Applicable.

ITEM 10.    CERTIFICATIONS.

     Each of the Reporting Persons hereby makes the following certification:

     By signing  below I certify  that,  to the best of my knowledge and belief,
the  securities  referred  to above were not  acquired  and are not held for the
purpose of or with the effect of  changing  or  influencing  the  control of the
issuer of the  securities  and were not acquired and are not held in  connection
with or as a participant in any transaction having that purpose or effect.


                                       13


CUSIP No. 232824 30 0                   13G                  Page 14 of 14 Pages

                                    SIGNATURE

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

Dated: November 30, 2005
                                       /s/ Pasquale DeAngelis
                                       -----------------------------------------
                                       Pasquale   DeAngelis,   as  a  member  of
                                       ProQuest Associates III LLC and on behalf
                                       of ProQuest Investments III, L.P., and as
                                       a member of  ProQuest  Associates  II LLC
                                       and on behalf of ProQuest Investments II,
                                       L.P. and ProQuest Investments II Advisors
                                       Fund, L.P.


                                                          *                     
                                         ---------------------------------------
                                         Jay Moorin, individually


                                                          *                     
                                         ---------------------------------------
                                         Alain Schreiber, individually


*By: /s/ Pasquale DeAngelis
     --------------------------------------------
     Pasquale DeAngelis, Attorney-in-Fact
     Power of attorney filed as an exhibit hereto



                                  Index Exhibit
                                  SCHEDULE 13G

EXHIBIT NUMBER    EXHIBIT DESCRIPTION
--------------    -------------------
99.1              Joint Filing Agreement
99.2              Power of Attorney



                                       14