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

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                 SCHEDULE 13D/A
                                 (Rule 13d-102)

  INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(a) AND
               AMENDMENTS THEREFO FILED PURSUANT TO RULE 13d-2(a)

                                (AMENDMENT NO. 6)

                                BIOENVISION, INC.
                                (Name of Issuer)

                    COMMON STOCK, PAR VALUE $0.001 PER SHARE
                         (Title of Class of Securities)

                                    09059N100
                                 (CUSIP Number)

                                ANDREW NICHOLSON
                    PERSEUS-SOROS BIOPHARMACEUTICAL FUND, LP
                         888 SEVENTH AVENUE, 30TH FLOOR
                               NEW YORK, NY 10106
                            TEL. NO.: (212) 651-6383
                     (Name, Address and Telephone Number of
                                Person Authorized
                     to Receive Notices and Communications)

                                 with a copy to

                              JOHN C. KENNEDY, ESQ.
                  PAUL, WEISS, RIFKIND, WHARTON & GARRISON LLP
                           1285 AVENUE OF THE AMERICAS
                          NEW YORK, NEW YORK 10019-6064

                                 JULY 10, 2007
             (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 Sections 240.13d-1(e),  240.13d-1(f) or 240.13d-1(g), check
the following box [_].

*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 the  remainder  of this  cover page shall not be
deemed to be "filed" for the purposes of Section 18 of the Securities  Exchange
Act of 1934 ("Act") 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).

                        (continued on following pages)

                              Page 1 of 15 pages)
===============================================================================


CUSIP NO. 09059N100                                                Page 2 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         Perseus-Soros BioPharmaceutical Fund, LP
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY

-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)

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

         75,009 (1)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         PN
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.


CUSIP NO. 09059N100                                                Page 3 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         Perseus-Soros Partners, LLC
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists  of  75,009  shares  of  Common  Stock   beneficially   owned  by
     Perseus-Soros  Partners,  LLC  ("Perseus-Soros  Partners")  solely  in its
     capacity as sole general partner of Perseus-Soros.



CUSIP NO. 09059N100                                                Page 4 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         Perseus BioTech Fund Partners, LLC
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                 (a)  [_]
                                                                 (b)  [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists of 75,009  shares of Common Stock  beneficially  owned by Perseus
     BioTech Fund Partners,  LLC ("Perseus Partners") solely in its capacity as
     a managing  member of  Perseus-Soros  Partners,  which is the sole general
     partner of Perseus-Soros.



CUSIP NO. 09059N100                                                Page 5 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         SFM Participation, L.P.
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         PN
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists  of  75,009  shares  of Common  Stock  beneficially  owned by SFM
     Participation,  L.P.  ("SFM  Participation")  solely in its  capacity as a
     managing  member  of  Perseus-Soros  Partners,  which is the sole  general
     partner of Perseus-Soros.



CUSIP NO. 09059N100                                                Page 6 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         SFM AH LLC
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists of 75,009 shares of Common Stock beneficially owned by SFM AH LLC
     ("SFM  AH")  solely  in  its  capacity  as  the  general  partner  of  SFM
     Participation, which is a managing member of Perseus-Soros Partners, which
     is the sole general partner of Perseus-Soros.



CUSIP NO. 09059N100                                                Page 7 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         Perseuspur, LLC
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists  of  75,009  shares  of  Common  Stock   beneficially   owned  by
     Perseuspur,  L.L.C.  ("Perseuspur") solely in its capacity as the managing
     member of Perseus  Partners,  which is a managing member of  Perseus-Soros
     Partners, which is the sole general partner of Perseus-Soros.



CUSIP NO. 09059N100                                                Page 8 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         Frank H. Pearl (in the capacity described herein)
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         United States
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         IN
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists of 75,009 shares of Common Stock  beneficially owned by Mr. Pearl
     solely in his  capacity  as the sole  member of  Perseuspur,  which is the
     managing  member  of  Perseus  Partners,  which is a  managing  member  of
     Perseus-Soros   Partners,   which  is  the   sole   general   partner   of
     Perseus-Soros.



CUSIP NO. 09059N100                                                Page 9 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         Soros Fund Management LLC
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         Delaware
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         OO; IA
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists of 75,009 shares of Common Stock beneficially owned by Soros Fund
     Management  LLC ("SFM LLC")  solely in its  capacity as the sole  managing
     member of SFM AH, which is the sole general partner of SFM  Participation,
     which is a managing member of  Perseus-Soros  Partners,  which is the sole
     general partner of Perseus-Soros.




CUSIP NO. 09059N100                                               Page 10 of 15

                                  SCHEDULE 13D
-------------------------------------------------------------------------------
1        NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

         George Soros (in the capacity described herein)
-------------------------------------------------------------------------------
2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

                                                                (a)   [_]
                                                                (b)   [X]
-------------------------------------------------------------------------------
3        SEC USE ONLY


-------------------------------------------------------------------------------
4        SOURCE OF FUNDS

         Not Applicable
-------------------------------------------------------------------------------
5        CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
         ITEMS 2(d) OR 2(e)
                                                                      [_]
-------------------------------------------------------------------------------
6        CITIZENSHIP OR PLACE OF ORGANIZATION

         United States
-------------------------------------------------------------------------------
                                          7     SOLE VOTING POWER
                                                0
             NUMBER OF                    -------------------------------------
              SHARES                      8     SHARED VOTING POWER
           BENEFICIALLY                         75,009 (1)(2)
             OWNED BY                     -------------------------------------
               EACH                       9     SOLE DISPOSITIVE POWER
             REPORTING                          0
              PERSON                      -------------------------------------
               WITH                       10    SHARED DISPOSITIVE POWER
                                                75,009 (1)(2)

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

         75,009 (1)(2)
-------------------------------------------------------------------------------
12       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

                                                                      [_]
-------------------------------------------------------------------------------
13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         0.001%
-------------------------------------------------------------------------------
14       TYPE OF REPORTING PERSON

         IA
-------------------------------------------------------------------------------

------------
(1)  Assumes exercise of a Warrant to purchase 75,009 shares of Common Stock.
(2)  Consists of 75,009 shares of Common Stock beneficially owned by Mr. Soros,
     Chairman of SFM LLC, which is the sole managing member of SFM AH, which is
     the sole general partner of SFM Participation,  which is a managing member
     of  Perseus-Soros   Partners,   which  is  the  sole  general  partner  of
     Perseus-Soros.



CUSIP NO. 09059N100                                               Page 11 of 15

                                  SCHEDULE 13D


Item 1.   SECURITY AND ISSUER.

                This  Amendment  No. 6 to  Schedule  13D  relates to the common
stock, par value $0.001 per share (the "Common Stock") of Bioenvision,  Inc., a
Delaware  corporation  (the  "Company").  This  Amendment No. 6  supplementally
amends the initial  statement on Schedule 13D,  filed with the  Securities  and
Exchange  Commission  on May 20, 2002,  as amended by Amendment  No. 1 filed on
January 8, 2003,  Amendment No. 2 filed on May 17, 2004,  Amendment No. 3 filed
on December 17, 2004, Amendment No. 4 filed on December 21, 2004, and Amendment
No. 5 filed on May 30, 2007 (collectively,  the "Initial Statement"),  filed by
the  Reporting  Persons,  and is being  filed  pursuant to Rule 13d-2 under the
Securities  Exchange Act of 1934, as amended (the "Exchange  Act"). The address
of the  principal  executive  offices of the Company is 345 Park  Avenue,  41st
Floor, New York, New York 10154.  Capitalized terms used but not defined herein
shall have the meanings ascribed to them in the Initial Statement.  The Initial
Statement is supplementally amended as follows.


Item 2.   IDENTITY AND BACKGROUND.

                (a)   No material change.

                (b)   No material change.

                (c)   No material change.

                (d)   No material change.

                (e)   No material change.

                (f)   No material change.


Item 3.   SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

                No material change.


Item 4.   PURPOSE OF TRANSACTION.

                ITEM 4 IS HEREBY  AMENDED  BY ADDING THE  FOLLOWING  AT THE END
THEREOF:

                The Offer contemplated by the Merger Agreement expired at 12:01
a.m.,  New York City time, on July 10, 2007. At that time,  Merger Sub accepted
for  payment  the  shares  of  Common  Stock  of  the  Company  or   securities
exchangeable,  exercisable or convertible into Common Stock that  Perseus-Soros
has tendered pursuant to the Offer (collectively,  the "Tendered  Securities").



CUSIP NO. 09059N100                                               Page 12 of 15

                                  SCHEDULE 13D


In accordance with the Merger Agreement, Perseus-Soros surrendered its Tendered
Securities  in exchange  for  consideration  equal to $5.60 per share of Common
Stock and  $11.20  per  share of Series A  Convertible  Preferred  Stock,  plus
payment  of  accrued  but  unpaid  dividends  with  respect  to such  Series  A
Convertible Preferred Stock.


Item 5.   INTEREST IN SECURITIES OF THE ISSUER.

                Item 5 is  hereby  amended  and  restated  in its  entirety  as
follows:

                In accordance with the Company's  Quarterly Report on Form 10-Q
for the quarter ended March 31, 2007, as of May 3, 2007,  there were 55,035,739
shares of Common Stock outstanding.

                (a)  Pursuant to Rule 13d-3 of the  Exchange  Act,  each of the
Reporting Persons may be deemed the beneficial owner of 75,009 shares of Common
Stock  issuable  upon the exercise of the May Warrants  held for the account of
Perseus-Soros, which constitutes 0.001% of the total number of shares of Common
Stock outstanding.

                (b) By  virtue  of the  relationships  between  and  among  the
Reporting  Persons described in Item 2 of the Initial Statement and as a result
of the provisions of the Voting Agreement, each of the Reporting Persons may be
deemed to have shared power to direct the voting and  disposition of the 75,009
shares  of Common  Stock  beneficially  owned by  Perseus-Soros,  assuming  the
exercise of the May Warrants held for the account of Perseus-Soros.

                (c) On July 10, 2007,  as a result of the  consummation  of the
Offer pursuant to the Merger Agreement and Voting Agreement described in Item 4
above,  Merger Sub  accepted for payment (A)  3,375,004  shares of Common Stock
held  for the  account  of  Perseus-Soros,  and  (B)  2,250,000  shares  of the
Company's  Series A Preferred Stock held for the account of  Perseus-Soros.  In
exchange for these Tendered Securities,  Perseus-Soros  received  consideration
from  Merger Sub equal to $5.60 per share of Common  Stock and $11.20 per share
of Series A Convertible  Preferred Stock, plus any accrued but unpaid dividends
with respect to such Series A Convertible Preferred Stock.

                (d) The partners of Perseus-Soros have the right to participate
in the receipt of dividends  from, or proceeds from the sales of, the shares of
Common  Stock or other  securities  held for the  account of  Perseus-Soros  in
accordance with their ownership interests in Perseus-Soros.

                (e) As of July 10, 2007, the Reporting Persons ceased to be the
beneficial  owners of more than five  percent of the shares of the Common Stock
of the Company.



CUSIP NO. 09059N100                                               Page 13 of 15

                                  SCHEDULE 13D


Item 6.   CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH
          RESPECT TO SECURITIES OF THE ISSUER.

                The information in Item 4 is incorporated  herein by reference;
otherwise, the information set forth in Item 6 of the Initial Statement remains
unchanged.


Item 7.  MATERIAL TO BE FILED AS EXHIBITS.

                Exhibit 1:    Joint Filing Agreement,  dated December 22, 2004,
                              among (i) Perseus-Soros  BioPharmaceutical  Fund,
                              LP,  (ii)  Perseus-Soros   Partners,  LLC,  (iii)
                              Perseus  BioTech  Fund  Partners,  LLC,  (iv) SFM
                              Participation,  L.P.,  (v) SFM AH LLC, (vi) Frank
                              H. Pearl,  (vii) George Soros,  (viii) Soros Fund
                              Management  L.L.C.,  and (ix) Perseuspur,  L.L.C.
                              (previously filed)

                Exhibit 2:    Tender and Voting Agreement,  dated May 29, 2007,
                              by and among Genzyme Corporation, a Massachusetts
                              corporation,  Wichita Bio Corporation, a Delaware
                              corporation  and direct or indirect  wholly owned
                              subsidiary    of   Genzyme    Corporation,    and
                              Perseus-Soros    BioPharmaceutical    Fund,    LP
                              (previously filed)

                Exhibit 3:    Power of Attorney,  dated May 9, 2007, appointing
                              Kenneth   M.   Socha   and   Rona    Kennedy   as
                              Attorney-in-Fact for Frank H. Pearl.  (previously
                              filed)

                Exhibit 4:    Power  of   Attorney,   dated   June  16,   2005,
                              appointing  Armando T.  Belly,  Jodye  Anzalotta,
                              Maryann  Canfield,  Jay  Schoenfarber  and Robert
                              Soros  as  Attorney-in-Fact   for  George  Soros.
                              (previously filed)



CUSIP NO. 09059N100                                               Page 14 of 15

                                  SCHEDULE 13D


                                   SIGNATURE

               After  reasonable  inquiry and to the best of its  knowledge and
belief,  each of the  undersigned  certifies that the  information set forth in
this statement is true, complete and correct.

Dated:  July 12, 2007

                                PERSEUS-SOROS BIOPHARMACEUTICAL FUND, LP

                                By:     Perseus-Soros Partners, LLC
                                        General Partner

                                By:     SFM Participation, L.P.
                                        Managing Member

                                By:     SFM AH LLC
                                        General Partner

                                By:     Soros Fund Management LLC
                                        Managing Member

                                By:     /s/  Jodye Anzalotta
                                        ---------------------------------------
                                        Name:   Jodye Anzalotta
                                        Title:  Assistant General Counsel


                                PERSEUS-SOROS PARTNERS, LLC

                                By:     SFM Participation, L.P.
                                        Managing Member

                                By:     SFM AH LLC
                                        General Partner

                                By:     Soros Fund Management LLC
                                        Managing Member

                                By:     /s/  Jodye Anzalotta
                                        ---------------------------------------
                                        Name:   Jodye Anzalotta
                                        Title:  Assistant General Counsel


                                PERSEUS BIOTECH FUND PARTNERS, LLC

                                By:     Perseuspur, LLC
                                        Managing Member

                                By:     /s/ Rona Kennedy
                                        ---------------------------------------
                                        Name:   Rona Kennedy
                                        Title:  Secretary and Treasurer


                                PERSEUSPUR, LLC

                                By:     /s/ Rona Kennedy
                                        ---------------------------------------
                                        Name:   Rona Kennedy
                                        Title:  Secretary and Treasurer



CUSIP NO. 09059N100                                               Page 15 of 15

                                  SCHEDULE 13D



                                MR. FRANK H. PEARL

                                By:     /s/ Rona Kennedy
                                        ---------------------------------------
                                        Name:   Rona Kennedy
                                        Title:  Attorney-in-Fact


                                SFM PARTICIPATION, L.P.

                                By:     SFM AH LLC
                                        General Partner

                                By:     Soros Fund Management LLC
                                        Managing Member

                                By:     /s/  Jodye Anzalotta
                                        ---------------------------------------
                                        Name:   Jodye Anzalotta
                                        Title:  Assistant General Counsel


                                SFM AH LLC

                                By:     Soros Fund Management LLC
                                        Managing Member

                                By:     /s/  Jodye Anzalotta
                                        ---------------------------------------
                                        Name:   Jodye Anzalotta
                                        Title:  Assistant General Counsel


                                MR. GEORGE SOROS

                                By:     /s/  Jodye Anzalotta
                                        ---------------------------------------
                                        Name:   Jodye Anzalotta
                                        Title:  Attorney-in-Fact


                                SOROS FUND MANAGEMENT LLC

                                By:     /s/  Jodye Anzalotta
                                        ---------------------------------------
                                        Name:   Jodye Anzalotta
                                        Title:  Assistant General Counsel