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

                                  SCHEDULE 13D
                                 (Rule 13d-101)

                    Under the Securities Exchange Act of 1934
                                (Amendment No. 3)
--------------------------------------------------------------------------------

                             Seattle Genetics, Inc.
                                (Name of Issuer)

                    Common Stock, par value $0.001 per share
                         (Title of Class of Securities)

                                    812578102
                                 (CUSIP Number)

                               Phillip Isom, Esq.
                              O'Melveny & Myers LLP
                                 7 Times Square
                               New York, NY 10036
                            Telephone: (212) 408-2418
   --------------------------------------------------------------------------
            (Name, Address and Telephone Number of Person Authorized
                     to Receive Notices and Communications)

                                December 31, 2005
                                -----------------
             (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 Rule 13d-l(e), 13d-l(f) or 13d-l(g), check the
following box |_|

      Note: Schedules filed in paper format shall include a signed original and
five copies of the schedule, including all exhibits. See Rule 13d-7 for other
parties to whom copies are to be sent. 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 disclosures provided in a prior cover page. The
information required on this cover page shall not be deemed to be "filed" for
the purpose of Section 18 of the Securities Exchange Act of 1934 ("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)


                                  Page 1 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
--------------------------------------------------------------------------------
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

         J.P. Morgan Partners (BHCA), L.P.
         13-3371826
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS

                  WC
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
SHARES BENEFICIALLY OWNED    7        SOLE VOTING POWER
 BY EACH REPORTING PERSON             5,427,325 (includes shares of Series A
           WITH              Convertible Preferred Stock, warrant to purchase
                             601,925 shares of common stock and option to
                             purchase 10,000 shares of common stock)
                             ---------------------------------------------------
                             8        SHARED VOTING POWER
                                                        0
                             ---------------------------------------------------
                             9        SOLE DISPOSITIVE POWER
                                      5,427,325 (includes shares of Series A
                             Convertible Preferred Stock, warrant to purchase
                             601,925 shares of common stock and option to
                             purchase 10,000 shares of common stock)
                             ---------------------------------------------------
                             10       SHARED DISPOSITIVE POWER
                                                                0
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         5,427,325 (includes shares of Series A Convertible Preferred Stock,
         warrant to purchase 601,925 shares of common stock and option to
         purchase 10,000 shares of common stock)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(1)                                             |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           10.9 %
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

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

(1) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 2 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

         J.P. Morgan Partners Global Investors, L.P.
            13-4197054
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
SHARES BENEFICIALLY OWNED     7        SOLE VOTING POWER
 BY EACH REPORTING PERSON              912,791 (includes shares of Series A
           WITH               Convertible Preferred Stock and warrant to
                              purchase 101,421 shares of Common Stock)
                              --------------------------------------------------
                              8        SHARED VOTING POWER
                                                         0
                              --------------------------------------------------
                              9        SOLE DISPOSITIVE POWER
                                       912,791 (includes shares of Series A
                              Convertible Preferred Stock and warrant to
                              purchase 101,421 shares of Common Stock)
                              --------------------------------------------------
                              10       SHARED DISPOSITIVE POWER
                                                              0
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         912,791 (includes shares of Series A Convertible Preferred Stock and
         warrant to purchase 101,421 shares of Common Stock)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(2)                                             |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           1.8%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

--------------------------
(2) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 3 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

         J.P. Morgan Partners Global Investors A, L.P.
            26-0032493
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
SHARES BENEFICIALLY OWNED    7        SOLE VOTING POWER
 BY EACH REPORTING PERSON             124,436 (includes shares of Series A
           WITH              Convertible Preferred Stock and warrant to purchase
                             13,826 shares of Common Stock)
                             ---------------------------------------------------
                             8        SHARED VOTING POWER
                                                        0
                             ---------------------------------------------------
                             9        SOLE DISPOSITIVE POWER
                                      124,436 (includes shares of Series A
                             Convertible Preferred Stock and warrant to purchase
                             13,826 shares of Common Stock)
                             ---------------------------------------------------
                             10       SHARED DISPOSITIVE POWER
                                                             0
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         124,436 (includes shares of Series A Convertible Preferred Stock and
         warrant to purchase 13,826 shares of Common Stock)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(3)                                             |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           0.3 %
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

-----------------------------
(3) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 4 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

         J.P. Morgan Partners Global Investors (Cayman), L.P.
         13-4197057
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
         PURSUANT TO ITEMS 2(d) or 2(e)                    |_|
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION
                  Cayman Islands
--------------------------------------------------------- ----------------------
SHARES BENEFICIALLY OWNED     7        SOLE VOTING POWER
 BY EACH REPORTING PERSON              463,298 (includes shares of Series A
           WITH               Convertible Preferred Stock and warrant to
                              purchase 51,478 shares of Common Stock)
                              --------------------------------------------------
                              8        SHARED VOTING POWER
                                                         0
                              --------------------------------------------------
                              9        SOLE DISPOSITIVE POWER
                                       463,298 (includes shares of Series A
                              Convertible Preferred Stock and warrant to
                              purchase 51,478 shares of Common Stock)
                              --------------------------------------------------
                              10       SHARED DISPOSITIVE POWER
                                                              0
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         463,298 (includes shares of Series A Convertible Preferred Stock and
         warrant to purchase 51,478 shares of Common Stock)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(4)                                             |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           0.9%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

--------------------------
(4) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 5 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

         J.P. Morgan Partners Global Investors (Cayman) II, L.P.
         26-0005546
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
         PURSUANT TO ITEMS 2(d) or 2(e)                    |_|
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION
                  Cayman Islands
--------------------------------------------------------- ----------------------
SHARES BENEFICIALLY OWNED    7        SOLE VOTING POWER
 BY EACH REPORTING PERSON             51,626 (includes shares of Series A
           WITH              Convertible Preferred Stock and warrant to purchase
                             5,736 shares of Common Stock)
                             ---------------------------------------------------
                             8        SHARED VOTING POWER
                                                        0
                             ---------------------------------------------------
                             9        SOLE DISPOSITIVE POWER
                                      51,626 (includes shares of Series A
                             Convertible Preferred Stock and warrant to purchase
                             5,736 shares of Common Stock)
                             ---------------------------------------------------
                             10       SHARED DISPOSITIVE POWER
                                                             0
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         51,626 (includes shares of Series A Convertible Preferred Stock and
         warrant to purchase 5,736 shares of Common Stock)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(5)                  |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           0.1 %
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

-------------------------
(5) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 6 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

         J.P. Morgan Partners Global Investors (Selldown), L.P.
         56-2489868
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
         PURSUANT TO ITEMS 2(d) or 2(e)                    |_|
--------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION
                  Cayman Islands
--------------------------------------------------------- ----------------------
SHARES BENEFICIALLY OWNED    7        SOLE VOTING POWER
 BY EACH REPORTING PERSON             343,024 (includes shares of Series A
           WITH              Convertible Preferred Stock and warrant to purchase
                             38,114 shares of Common Stock)
                             ---------------------------------------------------
                             8        SHARED VOTING POWER
                                                        0
                             ---------------------------------------------------
                             9        SOLE DISPOSITIVE POWER
                                      343,024 (includes shares of Series A
                             Convertible Preferred Stock and warrant to purchase
                             38,114 shares of Common Stock)
                             ---------------------------------------------------
                             10       SHARED DISPOSITIVE POWER
                                                             0
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         343,024 (includes shares of Series A Convertible Preferred Stock and
         warrant to purchase 38,114 shares of Common Stock)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(6)                                             |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           0.7 %
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

-----------------------
(6) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 7 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
     1      NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS

                     Julian C. Baker
--------------------------------------------------------------------------------
     2      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (See Instructions)                             (a) |_|

                                                           (b) |X|
--------------------------------------------------------------------------------
     3      SEC USE ONLY
--------------------------------------------------------------------------------
            SOURCE OF FUNDS (See Instructions)
     4
                     WC
--------------------------------------------------------------------------------
     5      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
            PURSUANT TO ITEMS 2(d) OR 2(e)                 |_|
--------------------------------------------------------------------------------
     6      CITIZENSHIP OR PLACE OF ORGANIZATION
            United States
--------------------------------------------------------------------------------
NUMBER OF SHARES               7   SOLE VOTING POWER
BENEFICIALLY OWNED BY EACH
REPORTING PERSON                            -0-
WITH

                               -------------------------------------------------
                               8   SHARED VOTING POWER

                                   8,507,432 (includes shares of Series A
                                   Convertible Preferred Stock and warrant to
                                   purchase 812,500 shares of Common Stock)
                               -------------------------------------------------
                                   SOLE DISPOSITIVE POWER
                               9
                                            -0-
                               -------------------------------------------------
                                   SHARED DISPOSITIVE POWER

                               10  8,507,432 (includes shares of Series A
                                   Convertible Preferred Stock and warrant to
                                   purchase 812,500 shares of Common Stock)
--------------------------------------------------------------------------------
    11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

             8,507,432 (includes shares of Series A Convertible Preferred
             Stock and warrant to purchase [812,500] shares of Common Stock)
--------------------------------------------------------------------------------
    12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
             CERTAIN SHARES (See Instructions)(7)          |X|
--------------------------------------------------------------------------------
    13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                      16.5%
--------------------------------------------------------------------------------
             TYPE OF REPORTING PERSON (See Instructions)
    14
                      IN
--------------------------------------------------------------------------------

----------------------
(7) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 8 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
     1      NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS

                     Felix J. Baker
--------------------------------------------------------------------------------
     2      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (See Instructions)                             (a)

                                                           (b) |X|
--------------------------------------------------------------------------------
     3      SEC USE ONLY
--------------------------------------------------------------------------------
            SOURCE OF FUNDS (See Instructions)
     4
                     WC
--------------------------------------------------------------------------------
     5      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
            PURSUANT TO ITEMS 2(d) OR 2(e)                 [ ]
--------------------------------------------------------------------------------
     6      CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------------------------------------------------------------------
NUMBER OF SHARES                7   SOLE VOTING POWER
BENEFICIALLY OWNED BY EACH
REPORTING                                    -0-
PERSON WITH
                                ------------------------------------------------
                                8   SHARED VOTING POWER

                                    8,507,432 (includes shares of Series A
                                    Convertible Preferred Stock and warrant to
                                    purchase 812,500 shares of Common Stock)
                                ------------------------------------------------
                                    SOLE DISPOSITIVE POWER
                                9
                                             -0-
--------------------------------------------------------------------------------
                                    SHARED DISPOSITIVE POWER

                                10  8,507,432 (includes shares of Series A
                                    Convertible Preferred Stock and warrant to
                                    purchase 812,500 shares of Common Stock)
--------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            8,507,432 (includes shares of Series A Convertible Preferred Stock
            and warrant to purchase 812,500 shares of Common Stock)
--------------------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES(8)                              |X|
--------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                     16.5%
--------------------------------------------------------------------------------
            TYPE OF REPORTING PERSON (See Instructions)
    14
                     IN
--------------------------------------------------------------------------------

-------------------
(8) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                  Page 9 of 29


--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Delphi Ventures VI, L.P.
            42-1561726
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
    SHARES BENEFICIALLY      7   SOLE VOTING POWER
       OWNED BY EACH                             0
    REPORTING PERSON WITH    ---------------------------------------------------
                             8   SHARED VOTING POWER
                                 2,227,725 (includes 1,980,200 shares of
                                 Common Stock issuable upon conversion of the
                                 Series A Convertible Preferred Stock and
                                 247,525 shares of Common Stock issuable upon
                                 exercise of the Warrants)
                             ---------------------------------------------------
                             9   SOLE DISPOSITIVE POWER
                                                   0
                             ---------------------------------------------------
                             10  SHARED DISPOSITIVE POWER
                                 2,227,725 (includes [1,980,200] shares of
                                 Common Stock issuable upon conversion of the
                                 Series A Convertible Preferred Stock and
                                 247,525 shares of Common Stock issuable upon
                                 exercise of the Warrants)
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         2,227,725 (includes 1,980,200 shares of Common Stock issuable upon
         conversion of the Series A Convertible Preferred Stock and 247,525
         shares of Common Stock issuable upon exercise of the Warrants)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(9)                                 |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           5.0%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

---------------------
(9)The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                 Page 10 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Delphi BioInvestments VI, L.P.
            04-3760672
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
SHARES BENEFICIALLY OWNED    7     SOLE VOTING POWER
   BY EACH REPORTING                               0
     PERSON WITH
                             ---------------------------------------------------
                             8     SHARED VOTING POWER
                                   22,275 (includes 19,800 shares of Common
                                   Stock issuable upon conversion of the Series
                                   A Convertible Preferred Stock and 2,475
                                   shares of Common Stock issuable upon exercise
                                   of the Warrants)
                             ---------------------------------------------------
                             9     SOLE DISPOSITIVE POWER
                                                     0
                             ---------------------------------------------------
                              10   SHARED DISPOSITIVE POWER
                                   22,275 (includes 19,800 shares of Common
                                   Stock issuable upon conversion of the Series
                                   A Convertible Preferred Stock and 2,475
                                   shares of Common Stock issuable upon exercise
                                   of the Warrants)
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         22,275 (includes 19,800 shares of Common Stock issuable upon
         conversion of the Series A Convertible Preferred Stock and 2,475
         shares of Common Stock issuable upon exercise of the Warrants)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(10)                                |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           0 %
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  PN
--------------------------------------------------------------------------------

---------------------------
(10) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                 Page 11 of 29


Schedule 13D
Cusip No. 812578102

--------------------------------------------------------------------------------
1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Delphi Management Partners VI, L.L.C.
--------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                           (a) |_|
                                                           (b) |X|
--------------------------------------------------------------------------------
3        SEC USE ONLY
--------------------------------------------------------------------------------
4        SOURCE OF FUNDS
                  WC
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
  SHARES BENEFICIALLY OWNED    7   SOLE VOTING POWER
      BY EACH REPORTING                            0
        PERSON WITH
                               -------------------------------------------------
                               8   SHARED VOTING POWER
                                   2,250,000 (includes 2,000,000 shares of
                                   Common Stock issuable upon conversion of the
                                   Series A Convertible Preferred Stock and
                                   250,000 shares of Common Stock issuable
                                   upon exercise of the Warrants)
                               -------------------------------------------------
                               9   SOLE DISPOSITIVE POWER
                                              0
                               -------------------------------------------------
                               10  SHARED DISPOSITIVE POWER
                                   2,250,000 (includes 2,000,000 shares of
                                   Common Stock issuable upon conversion of the
                                   Series A Convertible Preferred Stock and
                                   250,000 shares of Common Stock issuable
                                   upon exercise of the Warrants)
--------------------------------------------------------------------------------
11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
         2,250,000 (includes 2,000,000 shares of Common Stock issuable upon
         conversion of the Series A Convertible Preferred Stock and 250,000
         shares of Common Stock issuable upon exercise of the Warrants)
--------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES(11)                                |X|
--------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                           5.1%
--------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON
                  OO
--------------------------------------------------------------------------------

------------------------
(11) The Reporting Person above is party to a voting agreement contained in the
Investors Rights Agreement described herein. As a result, the parties to the
Investors Rights Agreement may be deemed to constitute a "group" for purposes of
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act")
with respect to 18,069,927 shares of Common Stock (defined herein), representing
30.5% of the outstanding voting power of the Issuer. The Reporting Person above
disclaims beneficial ownership of any securities held by any other Reporting
Person and the filing of this Statement on Schedule 13D shall not be deemed an
admission that the Reporting Person above and any other person or persons
constitute a "group" for purposes of Section 13(d)(3) of the Act or Rule 13d-5
thereunder.


                                 Page 12 of 29


Schedule 13D
Cusip No. 812578102

Preliminary Statement: This Schedule 13D is being amended to reflect an increase
in the holdings of JPMP (BHCA) (as hereinafter defined) through an Option to
purchase 10,000 shares of the Issuer's Common Stock and a change in the
executive officers and directors of the controlling persons of the JPMP
Reporting Persons.

Item 1.  Security and Issuer.

         The class of equity securities to which this statement (this
         "Statement") relates is the Common Stock, par value $0.001 per share
         (the "Common Stock") of Seattle Genetics, Inc., a Delaware corporation
         (the "Issuer" or "Company"). The Issuer's principal executive offices
         are located at 21823 -- 30th Drive S.E., Bothell, WA 98021.

Item 2.  Identity and Background.

         JPMP Reporting Persons

         This Statement is being filed by: (i) J.P. Morgan Partners (BHCA),
         L.P., a limited partnership organized under the laws of Delaware ("JPMP
         (BHCA)"), whose principal office is located at 1221 Avenue of the
         Americas, New York, NY 10020, (ii) J.P. Morgan Partners Global
         Investors, L.P., a limited partnership organized under the laws of
         Delaware ("JPMP Global"), whose principal office is located at the same
         address as JPMP (BHCA), (iii) J.P. Morgan Partners Global Investors A,
         L.P., a limited partnership organized under the laws of Delaware ("JPMP
         Global A"), whose principal office is located at the same address as
         JPMP (BHCA), (iv) J.P. Morgan Partners Global Investors (Cayman), L.P.,
         a limited partnership organized under the laws of the Cayman Islands
         ("JPMP Cayman"), whose principal office is located at the same address
         as JPMP (BHCA), (v) J.P. Morgan Partners Global Investors (Cayman) II,
         L.P. a limited partnership organized under the laws of the Cayman
         Islands ("JPMP Cayman II"), whose principal address is located at the
         same address as JPMP (BHCA) and (vi) J.P. Morgan Partners Global
         Investors (Selldown), L.P., a Delaware Limited Partnership ("JPMP
         Selldown" and collectively with JPMP (BHCA), JPMP Global, JPMP Global A
         and JPMP Cayman, the "JPMP Reporting Persons"), whose principal office
         is located at the same address as JPMP (BHCA).

         JPMP (BHCA) is engaged in the venture capital, private equity and
         leveraged buyout business. The general partner of JPMP (BHCA) is JPMP
         Master Fund Manager, L.P., a Delaware limited partnership ("JPMP Master
         Fund"), whose principal business office is located at the same address
         as JPMP (BHCA), and is also engaged directly and indirectly (through
         affiliates) in the venture capital, private equity and leveraged buyout
         business.

         JPMP Global, JPMP Global A, JPMP Cayman, JPMP Cayman II and JPMP
         Selldown (collectively, the "Global Fund Entities") are also engaged in
         the venture capital, private equity and leveraged buyout business. The
         general partner of each of the Global Fund Entities is J.P. Morgan
         Partners Global Investors, L.P., a Delaware limited partnership ("JPMP
         Investors"), whose principal place of business is located at the same
         address as JPMP (BHCA). JPMP Investors is engaged indirectly in the
         venture capital, private equity and leveraged buyout business as
         general partner of each of the Global Fund Entities.


                                 Page 13 of 29


         The general partner of each of JPMP Master Fund and JPMP Investors is
         JPMP Capital Corp., a New York corporation ("JPMP Capital Corp."),
         whose principal business office is located at the same address as JPMP
         (BHCA), and is also engaged directly and indirectly (through
         affiliates) in the venture capital, private equity and leveraged buyout
         business. Set forth in Schedule A hereto and incorporated herein by
         reference are the names, business addresses, principal occupations and
         employments of each executive officer and director of JPMP Capital
         Corp.

         JPMP Capital Corp. is a wholly owned subsidiary of JPMorgan Chase &
         Co., a Delaware Corporation ("JPMorgan Chase") which is engaged
         (primarily through subsidiaries) in the commercial banking business
         with its principal office located at 270 Park Avenue, New York, NY
         10018. Set forth in Schedule B hereto and incorporated herein by
         reference are the names, business addresses, principal occupations and
         employments of each executive officer and director of JPMorgan Chase.

         Baker Reporting Persons

         This Statement is also being filed by: (i) Julian C. Baker and (ii)
         Felix J. Baker, each of whom is a United States citizen whose principal
         office is located at 667 Madison Avenue, New York, NY 10021
         (collectively, the "Baker Reporting Persons"). Set forth below is
         certain information with respect to the Baker Reporting Persons:

         Name                 Present Principal Occupation

         Julian C. Baker      Managing Member, Baker Bros. Advisors, LLC (an
                              entity engaged in investment activities)

         Felix J. Baker       Managing Member, Baker Bros. Advisors, LLC (an
                              entity engaged in investment activities)

         Delphi Reporting Persons

         This Statement is also being filed by: (i) Delphi Ventures VI, L.P., a
         limited partnership organized under the laws of Delaware ("Delphi
         Ventures"), whose principal office is located at 3000 Sand Hill Road,
         Building 1, Suite 135, Menlo Park, CA 94025, (ii) Delphi BioInvestments
         VI, L.P., a limited partnership organized under the laws of Delaware
         ("Delphi BioInvestments"), whose principal office is located at the
         same address as Delphi Ventures, and (iii) Delphi Management Partners
         VI, L.L.C., a Delaware limited liability company ("Delphi Management",
         and together with Delphi Ventures and Delphi BioInvestments, the
         "Delphi Reporting Persons") whose principal office is located at the
         same address as Delphi Ventures.


                                 Page 14 of 29


         The Delphi Reporting Persons are engaged in the venture capital
         business. The general partner of each of Delphi Ventures and Delphi
         BioInvestments is Delphi Management. Delphi Management is also engaged
         indirectly (through affiliates) in the venture capital business. Set
         forth in Schedule C hereto and incorporated herein by reference are the
         names, business addresses, principal occupations and employments of
         each managing member of Delphi Management.

         The Delphi Reporting Persons, the JPMP Reporting Persons and the Baker
         Reporting Persons are collectively referred to herein as the "Reporting
         Persons".

         During the last five years, none of the Reporting Persons have been
         convicted in any criminal proceeding (excluding traffic violations or
         similar misdemeanors) or have been a party to a civil proceeding of a
         judicial or administrative body of competent jurisdiction resulting in
         their being subject to a judgment, decree or final order enjoining
         future violations of, 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.

         JPMP Reporting Persons:

         The funds provided by JPMP (BHCA) and the Global Fund Entities for the
         purchase of the securities reported in Item 5 below were obtained from
         the contributed capital and available working capital of JPMP (BHCA)
         and the Global Fund Entities, which includes funds that are held
         available for such purpose.

         Baker Reporting Persons:

         The funds used by the limited partnerships controlled by Julian C.
         Baker and Felix J. Baker to purchase the securities reported in Item 5
         below were provided from the available working capital of such limited
         partnerships.

         Delphi Reporting Persons:

         The funds provided by Delphi Ventures and Delphi BioInvestments for the
         purchase of the securities reported in Item 5 below were obtained from
         the contributed capital and available working capital of Delphi
         Ventures and Delphi BioInvestments respectively, which includes funds
         that are held available for such purpose.


                                 Page 15 of 29


Item 4.  Purpose of Transactions.

         The securities referred to in Item 5 below (other than the Open Market
         Purchases (defined below) by the Baker Reporting Persons) were acquired
         pursuant to the Securities Purchase Agreement referred to in Item 6
         below solely for investment purposes. The Open Market Purchases by the
         Baker Reporting Persons were acquired pursuant to open market
         transactions for investment purposes only.

         The transactions described in Item 6 below are incorporated in their
         entirety herein by reference.

         Subject to the rights of the Reporting Persons set forth in the
         Securities Purchase Agreement and the Investors Rights Agreement
         referred to in Item 6 below, except as set forth in this Item 4, none
         of the JPMP Reporting Persons, the Baker Reporting Persons, or the
         Delphi Reporting Persons have a present plan or proposal that relates
         to or would result in any of the actions specified in clauses (a)
         through (j) of Item 4 of Schedule 13D. However, each of the JPMP
         Reporting Persons, the Baker Reporting Persons and the Delphi Reporting
         Persons reserves the right to propose or participate in future
         transactions which may result in one or more of such actions, including
         but not limited to, an extraordinary corporate transaction, such as a
         merger, reorganization or liquidation, sale of a material amount of
         assets of the Issuer or its subsidiaries, or other transactions which
         might have the effect of causing the Issuer's Common Stock to cease to
         be listed on the NASDAQ National Market System or causing the Common
         Stock to become eligible for termination of registration, under section
         12(g) of the Securities Exchange Act of 1934, as amended (the "Act").

Item 5.  Interest in Securities of the Issuer.

         The percentages of outstanding shares of the Issuer reported in this
         Item 5 are based on 42,140,428 shares of Common Stock outstanding as of
         December 31, 2005 as reported by the Issuer's Form 10K for fiscal year
         ended December 31, 2004.

         JPMP Reporting Persons

         JPMP (BHCA) beneficially owns 5,417,325 shares of the Issuer's Common
         Stock, which represents 11.4% of the Issuer's Common Stock. JPMP Global
         beneficially owns 912,791 shares of the Issuer's Common Stock, which
         represents 2.1% of the Issuer's Common Stock. JPMP Global A
         beneficially owns 124,436 shares of the Issuer's Common Stock, which
         represents 0.3% of the Issuer's Common Stock. JPMP Cayman beneficially
         owns 463,298 shares of the Issuer's Common Stock, which represents 1.1%
         of the Issuer's Common Stock. JPMP Cayman II beneficially owns 51,626
         shares of the Issuer's Common Stock, which represents 0.1% of the
         Issuer's Common Stock. JPMP Selldown beneficially owns 343,024 shares
         of the Issuer's Common Stock, which represents .8% the Issuer's Common
         Stock.


                                 Page 16 of 29


         JPMP Master Fund, as the General Partner of JPMP (BHCA), may be deemed
         to beneficially own the shares beneficially owned by JPMP (BHCA).

         JPMP Investors, as the General Partner of each of the Global Fund
         Entities, may be deemed to beneficially own the shares beneficially
         owned by each of the Global Fund Entities.

         JPMP Capital Corp., as the General Partner of each of JPMP Master Fund
         and JPMP Investors, may be deemed to beneficially own the shares
         beneficially owned by JPMP (BHCA) and each of the Global Fund Entities.

         JPMP Capital Corp. is a wholly owned subsidiary of JPMorgan Chase &
         Co., a publicly traded company.

         The foregoing shall not be an admission that JPMP Master Fund, JPMP
         Investors or JPMP Capital Corp. are the beneficial owners of the shares
         held by JPMP (BHCA) and/or the Global Fund Entities.

         Baker Reporting Persons:

         Set forth in the table below is the aggregate number of shares of
         Common Stock beneficially owned as of the date hereof by each of the
         limited partnerships controlled by the Baker Reporting Persons,
         together with the percentage of outstanding shares of Common Stock that
         such ownership represents based upon shares of Common Stock outstanding
         as of December 31, 2005 in each case taking into account the shares of
         Common Stock that can be acquired upon conversion of Series A
         Convertible Preferred Stock and exercise of the Warrants to purchase
         shares of Common Stock:

                                                   Number of    Percent of Class
                   Name                              Shares        Outstanding
         Baker Bros. Investments, L.P.               340,622            0.8%
         Baker Bros. Investments II, L.P.            348,321            0.8%
         Baker Biotech Fund I, L.P.                3,446,726            7.6%
         Baker Biotech Fund II, L.P.               3,162,612            7.0%
         Baker Biotech Fund II (Z), L.P.             436,638            1.0%
         Baker Biotech Fund III, L.P.                234,861            0.6%
         Baker Biotech Fund III (Z), L.P.             45,090            0.1%
         14159, L.P.                                  19,561           0.06%
         Baker/Tisch Investments, L.P.               473,001            1.1%
         Total                                     8,507,432           17.1%


                                 Page 17 of 29


         By virtue of their ownership of entities that have the power to control
         the investment decisions of the limited partnerships listed in the
         table above (collectively, the "Baker Entities"), Julian C. Baker and
         Felix J. Baker may each be deemed to be beneficial owners of securities
         owned by the Baker Entities and may be deemed to have shared power to
         vote or direct the vote and to dispose or direct the disposition of
         such securities, although such entities have the sole right to receive
         and power to direct the receipt of dividends from, and the proceeds
         from the sale of, securities owned by them.

         Additionally, Felix J. Baker is a director of the Issuer.

         Delphi Reporting Persons

         Delphi Ventures beneficially owns 2,227,725 shares of the Issuer's
         Common Stock, which represents 5.0% of the Issuer's Common Stock.
         Delphi BioInvestments beneficially owns 22,275 shares of the Issuer's
         Common Stock, which represents 0.0001% of the Issuer's Common Stock.

         As the general partner of Delphi Ventures and Delphi BioInvestments,
         Delphi Management may be deemed to beneficially own the shares
         beneficially owned by each of Delphi Ventures and Delphi
         BioInvestments.

         The foregoing shall not be an admission that Delphi Management is the
         beneficial owner of the shares held by Delphi Ventures and/or Delphi
         BioInvestments.

         The Reporting Persons are party to a voting agreement contained in the
         Investors Rights Agreement referred to in Item 6 below. The JPMP
         Reporting Persons, the Baker Reporting Persons, and the Delphi
         Reporting Persons together may be deemed to constitute a "group" for
         purposes of Section 13(d)(3) of the Act, with respect to [ ] shares of
         Common Stock, representing [ ]% of the outstanding voting power of the
         Issuer.

         Each of the Reporting Persons, however, disclaims beneficial ownership
         of any of the securities owned by any other Reporting Person and
         disclaims that it is a member of a "group" with any other persons
         either for purposes of Section 13(d)(3) of the Act or Rule 13d-5
         thereunder or this Statement or for any other purpose related to its
         beneficial ownership of the Issuer's securities. The filing of this
         Statement shall not be construed as an admission that the Reporting
         Person is the beneficial owner of such shares or that the Reporting
         Person and any of such other stockholders' constitute for purposes of
         Section 13(d) of the Act, a "group." Each Reporting Person is not
         responsible for the accuracy of any information filed in this Statement
         relating to any Reporting Person other than itself and its related
         persons or entities.

         There have been no transactions involving the Issuer's Common Stock
         during the past sixty days which are required to be reported in this
         Statement.

         No person other than the JPMP Reporting Persons, the Baker Reporting
         Persons and the Delphi Reporting Persons has the right to receive or
         the power to direct the receipt of dividends from or the proceeds from
         the sale of the Issuer's Common Stock owned beneficially by the JPMP
         Reporting Persons, the Baker Reporting Persons and the Delphi Reporting
         Persons.


                                 Page 18 of 29


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

         On May 12, 2003 the Company entered into the Securities Purchase
         Agreement (as amended by Amendment No. 1 dated as of May 14, 2003 and
         Amendment No. 2 dated as of June 2, 2003) (the "SPA"), with JPMP
         (BHCA), the Global Fund Entities, the Baker Entities, Delphi Ventures,
         Delphi BioInvestments, entities affiliated with BA Venture Partners and
         T. Rowe Price Health Sciences Fund, Inc. (collectively, the "Series A
         Investors"). Both the SPA and all exhibits thereto are attached as
         Exhibit A hereto and are incorporated herein in their entirety by
         reference.

         Pursuant to the SPA, the Issuer issued in a private placement (a)
         1,640,000 shares of the Company's Series A Convertible Preferred Stock
         (the "Preferred Stock") to the Series A Investors, as well as the
         reservation for issuance of 16,400,000 shares of the Company's Common
         Stock upon conversion of the Preferred Stock, and (b) warrants (the
         "Warrants") to purchase 2,050,000 shares of the Company's Common Stock
         and the reservation for issuance of 2,050,000 shares of the Company's
         Common Stock upon the exercise of such Warrants (together, the
         "Preferred Stock Financing"). The Preferred Stock has the rights,
         preferences and privileges set forth in the Certificate of Designations
         of Series A Convertible Preferred Stock as filed with the Secretary of
         State of the State of Delaware. The purchase price for the Preferred
         Stock was $25.00 per share. Each share of Preferred Stock is initially
         convertible into 10 shares of Common Stock at a fixed conversion price
         of $2.50 per share (subject to adjustment upon the occurrence of
         certain events including stock subdivisions, combinations, splits,
         stock dividends, capital reorganizations, or capital reclassifications
         of the Common Stock), at such holder's option at any time after the
         first anniversary of the closing of the Investors Rights Agreement
         among the Company, the Reporting Persons and the other investors named
         therein, dated as of July 8, 2003, a copy of which is attached hereto
         as Exhibit B and is incorporated herein in its entirety by reference
         (the "Investors Rights Agreement").

         The Warrants are immediately exercisable at a fixed purchase price of
         $6.25 per share of Common Stock and expire on December 31, 2011.

         Pursuant to the Certificate of Designations and the Investors Rights
         Agreement, the Series A Investors, voting together as a separate class,
         have the right to designate two members of the Company's Board of
         Directors so long as at least 37.5% of the shares of Preferred Stock
         issued at the closing of the Preferred Stock Financing remain
         outstanding. If between 18.75% and 37.5% of the shares of Preferred
         Stock issued at the closing of the Preferred Stock Financing are
         outstanding, the Series A Investors, voting together as a separate
         class, have the right to designate one member of the Company's Board of
         Directors. If less than 18.75% of the shares of Preferred Stock issued
         at the closing of the Preferred Stock Financing are outstanding, the
         rights of the Series A Investors to vote separately for the election of
         directors shall terminate.


                                 Page 19 of 29


         Pursuant to the terms of the Investors Rights Agreement, one director
         will be designated by the JPMP Reporting Persons and one director will
         be designated by the Baker Entities. The right of the JPMP Reporting
         Persons and the Baker Entities, as applicable, to designate a director
         terminates if the JPMP Reporting Persons or the Baker Entities, as
         applicable, hold less than 50% of the Preferred Stock (or Common Stock
         issued upon conversion thereof) purchased by it at the closing of the
         Preferred Stock Financing. Pursuant to these rights, the JPMP Reporting
         Persons designated Srinivas Akkaraju, M.D., Ph.D. as its representative
         on the Company's Board of Directors and the Baker Entities designated
         Felix Baker, Ph.D. as its representative on the Company's Board of
         Directors upon the closing of the Preferred Stock Financing. The Series
         A Investors do not have the right to vote on members of the Company's
         Board of Directors other than the nominees they designate.

         Each of JPMP (BHCA) and the Global Fund Entities is a party to the
         Regulatory Sideletter, dated as of July 8, 2003, by and among the
         Company, JPMP (BHCA) and each of the Global Fund Entities, a copy of
         which is attached as Exhibit C hereto and is incorporated herein in its
         entirety by reference.

Item 7.  Material to be Filed as Exhibits.

         SCHEDULE A

         Item 2 information for executive officers and directors of JPMP Capital
         Corp.

         SCHEDULE B

         Item 2 information for executive officers and directors of JPMorgan
         Chase.*

         SCHEDULE C

         Item 2 information for managing members of Delphi Management.*

         EXHIBIT A

         Securities Purchase Agreement dated as of May 12, 2003, by and among
         the Issuer and the Series A Investors incorporated by reference to
         Exhibit 10.1 of the Form 8-K filed with the Commission on May 15,
         2003.*

         EXHIBIT B

         Investors Rights Agreement dated as of July 8, 2003, by and among the
         Company and the Investors named therein incorporated by reference to
         Exhibit 4.2 of the Form 8-K filed with the Commission on May 15, 2003.*


                                 Page 20 of 29


         EXHIBIT C

         Regulatory Sideletter dated as of July 8, 2003, by and among the
         Company, JPMP (BHCA) and each of the Global Fund Entities.(*)

         EXHIBIT D

         Joint Filing Agreement dated as of May 17, 2004 among the JPMP
         Entities, the Bakers and the Delphi Entities.*

--------------------
(*)  Filed previously

                                 Page 21 of 29


                                    SIGNATURE

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

Dated: February 14, 2006

                                        J.P. MORGAN PARTNERS (BHCA), L.P.

                                        By:      JPMP Master Fund Manager, L.P.,
                                                 its general partner

                                        By:      JPMP Capital Corp.,
                                                 its general partner

                                        By:      /s/ Jeffrey  C. Walker
                                                 ----------------------
                                                 Name:  Jeffrey C. Walker
                                                 Title:  President

                                        J.P. MORGAN PARTNERS GLOBAL
                                        INVESTORS, L.P.

                                        By:      JPMP Global Investors, L.P.,
                                                 its general partner

                                        By:      JPMP Capital Corp.,
                                                 its general partner

                                        By:      /s/ Jeffrey  C. Walker
                                                 ----------------------
                                                 Name:  Jeffrey C. Walker
                                                 Title:  President

                                        J.P. MORGAN PARTNERS GLOBAL INVESTORS
                                        (CAYMAN), L.P.

                                        By:      JPMP Global Investors, L.P.,
                                                 its general partner

                                        By:      JPMP Capital Corp.,
                                                 its general partner

                                        By:      /s/ Jeffrey  C. Walker
                                                 ----------------------
                                                 Name:  Jeffrey C. Walker
                                                 Title:  President


                                 Page 22 of 29


                                        J.P. MORGAN PARTNERS GLOBAL
                                        INVESTORS A, L.P.

                                        By:      JPMP Global Investors, L.P.,
                                                 its general partner

                                        By:      JPMP Capital Corp.,
                                                 its general partner

                                        By:      /s/ Jeffrey  C. Walker
                                                 ----------------------
                                                 Name:  Jeffrey C. Walker
                                                 Title:  President

                                        J.P. MORGAN PARTNERS GLOBAL INVESTORS
                                        (SELLDOWN), L.P.

                                        By:      JPMP Global Investors, L.P.,
                                                 its general partner

                                        By:      JPMP Capital Corp.,
                                                 its general partner

                                        By:      /s/ Jeffrey  C. Walker
                                                 ----------------------
                                                 Name:  Jeffrey C. Walker
                                                 Title:  President


                                 Page 23 of 29


                                    SIGNATURE

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

Dated: February 14, 2006

                                        JULIAN C. BAKER

                                        By:   /s/  Julian C. Baker
                                              --------------------------
                                              Julian C. Baker

                                        FELIX J. BAKER

                                        By:   /s/  Felix J. Baker
                                              --------------------------
                                              Felix J. Baker


                                 Page 24 of 29


                                    SIGNATURE

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

Dated: February 14, 2006

                                        DELPHI VENTURES VI, L.P.

                                        By:      Delphi Management Partners VI,
                                                 L.L.C., its general partner

                                        By:      /s/ Deepika R. Pakianathan
                                                 -------------------------------
                                                 Deepika R. Pakianathan
                                                 Managing Member

                                        DELPHI BIOINVESTMENTS VI, L.P.

                                        By:      Delphi Management Partners VI,
                                                 L.L.C., its general partner

                                        By:      /s/ Deepika R. Pakianathan
                                                 -------------------------------
                                                 Deepika R. Pakianathan
                                                 Managing Member

                                        DELPHI MANAGEMENT PARTNERS VI, L.L.C.

                                        By:      /s/ Deepika R. Pakianathan
                                                 -------------------------------
                                                 Deepika R. Pakianathan
                                                 Managing Member


                                 Page 25 of 29


                                                                      SCHEDULE A

                               JPMP CAPITAL CORP.
                               ------------------

                              Executive Officers(1)
                              ---------------------

Chief Executive Officer                     William B. Harrison**
President                                   Jeffrey C. Walker*
Chief Investment Officer                    Arnold L. Chavkin*
Managing Director                           Srinivas Akkaraju*
Managing Director                           Christopher Albinson*
Managing Director                           Dr. Dana Beth Ardi*
Managing Director                           Christopher C. Behrens*
Managing Director                           John Breckenridge*
Managing Director                           Julie Casella-Esposito*
Managing Director                           Rodney A. Ferguson*
Managing Director                           Michael R. Hannon*
Managing Director                           Matthew Lori*
Managing Director                           Jonathan R. Lynch*
Managing Director                           Sunil Mishra*
Managing Director                           Stephen P. Murray*
Managing Director                           John Reardon*
Managing Director                           Faith Rosenfeld*
Managing Director                           Shahan D. Soghikian*
Managing Director                           William Stuek*
Managing Director                           Timothy J. Walsh*
Managing Director                           Richard D. Waters, Jr. *
Managing Director                           Damion E. Wicker, M.D.*

                                 Directors(13)
                                 -------------
                              William B. Harrison**
                               Jeffrey C. Walker*

-----------------------
(1)   Each of whom is a United States citizen.

*     Principal occupation is employee and/or officer of J.P. Morgan Partners,
      LLC. Business address is c/o J.P. Morgan Partners, LLC, 1221 Avenue of the
      Americas, New York, New York 10020.

**    Principal occupation is employee or officer of JPMorgan Chase & Co.
      Business address is c/o JPMorgan Chase & Co., 270 Park Avenue, New York,
      New York 10017.


                                 Page 26 of 29


                                                                      Schedule B

                              JPMORGAN CHASE & CO.
                              --------------------

                              Executive Officers(1)
                              ---------------------

Chairman of the Board and Chief Executive Officer       William B. Harrison Jr.*
President and Chief Operating Officer                   James Dimon*
Chief Information Officer                               Austin A. Adams*
Co-Chairman, Investment Bank                            Steven D. Black*
Chief Executive Officer, Card Services                  William I. Campbell*
Chief Financial Officer                                 Michael J. Cavanagh*
Chairman, West Coast Region                             David A. Coulter*
Director of Human Resources, Head of Real
   Estate/Facilities, General Services, Security        John J. Farrell*
Co-General Counsel                                      Joan Guggenheimer*
Director of Corporate Marketing and Communications      Frederick W. Hill*
Head, Commercial Banking                                Samuel Todd Maclin*
Head, Strategy and Business Development                 Jay Mandelbaum*
Co-General Counsel                                      William H. McDavid*
Chief Executive Officer, Treasury &
  Securities Services                                   Heidi Miller*
Head, Retail Financial Services                         Charles W. Scharf*
Executive Vice President, Card Services                 Richard J. Srednicki*
Head, Asset & Wealth Management                         James E. Staley*
Chief Risk Officer                                      Don M. Wilson III*
Co-Chairman, Investment Bank                            William T. Winters*

---------------------
(1)   Each of whom is a United States citizen.

*     Principal occupation is employee or officer of JPMorgan Chase & Co.
      Business address is c/o JPMorgan Chase & Co., 270 Park Avenue, New York,
      New York 10017.


                                 Page 27 of 29


                                  Directors(*)
                                  ------------

 Name                            Principal Occupation or Employment;
                                 Business or Residence Address
--------------------------------------------------------------------------------
 Hans W. Becherer                Retired Chairman of the Board and
                                 Chief Executive Officer
                                 Deere & Company
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                 New York, New York 10017
--------------------------------------------------------------------------------
 John H. Biggs                  Former Chairman and CEO
                                TIAA - CREF
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                 New York, New York 10017
--------------------------------------------------------------------------------
 Lawrence A. Bossidy            Retired Chairman of the Board
                                Honeywell International Inc.
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                  New York, New York 10017
--------------------------------------------------------------------------------
 Stephen B. Burke                President
                                 Comcast Cable Communications, Inc.
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                  New York, New York 10017
--------------------------------------------------------------------------------
James S. Crown                  President
                                Henry Crown and Company
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                 New York, New York 10017
--------------------------------------------------------------------------------
James Dimon                     President and Chief Operating Officer
                                JPMorgan Chase & Co.
                                270 Park Avenue, 8th Floor
                                New York, New York 10017-2070
--------------------------------------------------------------------------------
Ellen V. Futter                 President and Trustee
                                American Museum of Natural History
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                 New York, New York 10017
--------------------------------------------------------------------------------
 William H. Gray, III            Retired President and Chief Executive Officer
                                 The College Fund/UNCF
                                 c/o JPMorgan Chase & Co.
                                 270 Park Avenue
                                 New York, New York 10017
--------------------------------------------------------------------------------

-------------------------
*     Each of whom is a United States citizen.


                                 Page 28 of 29


 Name                            Principal Occupation or Employment;
                                 Business or Residence Address
--------------------------------------------------------------------------------
 William B. Harrison, Jr.     Chairman of the Board and Chief Executive Officer
                              JPMorgan Chase & Co.
                              270 Park Avenue, 8th Floor
                              New York, New York  10017-2070
--------------------------------------------------------------------------------
 Laban P. Jackson, Jr.        Chairman and Chief Executive Officer
                              Clear Creek Properties, Inc.
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                              New York, New York 10017
--------------------------------------------------------------------------------
 Lee R. Raymond              Chairman of the Board and Chief Executive Officer
                             Exxon Mobil Corporation
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                              New York, New York 10017
--------------------------------------------------------------------------------
 John W. Kessler             Owner
                             John W. Kessler Company
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                             New York, New York 10017
--------------------------------------------------------------------------------
 Robert I. Lipp              Chairman
                             The St. Paul Travelers Companies, Inc.
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                             New York, New York 10017
--------------------------------------------------------------------------------
 Richard A. Monoogian        Chairman and Chief Executive Officer
                             Masco Corporation
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                             New York, New York 10017
--------------------------------------------------------------------------------
 David C. Novak              Chairman and Chief Executive Officer
                             Yum! Brands, Inc.
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                              New York, New York 10017
--------------------------------------------------------------------------------
 John R. Stafford             Retired Chairman of the Board
                             Wyeth
                              c/o JPMorgan Chase & Co.
                              270 Park Avenue
                             New York, New York 10017
--------------------------------------------------------------------------------


                                 Page 29 of 29