Exhibit 10.1


AMENDMENT NO. 1 TO
RIGHTS AGREEMENT


THIS
AMENDMENT NO. 1 TO RIGHTS AGREEMENT (the “Amendment”) is made
as of the 30th day of May,
2007, by and between BIOENVISION, INC.,
a Delaware corporation (the “Company”), and AMERICAN
STOCK TRANSFER & TRUST COMPANY, a New York banking corporation
(the “Rights Agent”).


WHEREAS,
the Company has entered into an Agreement and Plan of Merger (as the same may
be amended from time to time, the “Merger Agreement”), among the Company,
Genzyme Corporation, a Massachusetts corporation (“Parent”), and Wichita Bio
Corporation, a Delaware corporation and a wholly-owned subsidiary of Parent (“Purchaser”),
pursuant to which Purchaser will: (i) make a tender offer to acquire (A) all of
the issued and outstanding shares of common stock of the Company, par value
$0.001 per share (“Common Stock”), and (B) all of the issued and outstanding
shares of Series A Convertible Participating Preferred Stock of the Company,
par value $0.001 per share (“Preferred Stock”) on the terms and subject to the
conditions set forth in the Merger Agreement (such tender offer, as it may be
amended from time to time, is referred to in this Amendment as the “Offer”),
(ii) be granted an irrevocable option to acquire certain additional shares of
Common Stock directly from the Company on the terms and subject to the
conditions set forth in the Merger Agreement (the “Top-Up Option”), and (iii)
after acquiring shares of Common Stock and Preferred Stock pursuant to the
Offer (and, if applicable, the Top-Up Option), Purchaser will merge with and
into the Company upon the terms and subject to the conditions set forth in the
Merger Agreement;


WHEREAS,
the Company and the Rights Agent are parties to that certain
Rights Agreement dated November 17, 2004 (the “Rights Agreement”);


WHEREAS,
the Company desires to amend the Rights Agreement in connection with the
execution and delivery of the Merger Agreement; and


WHEREAS,
the Board of Directors of the Company has approved this Amendment and
authorized its appropriate officers to execute and deliver the same to the
Rights Agent.


NOW,
THEREFORE, in accordance with the procedures for amendment of
the Rights Agreement set forth in Section 27 thereof, and in consideration of
the foregoing and the mutual agreements herein set forth, the parties hereby
agree as follows:


1.            
Capitalized terms that are not otherwise defined herein shall
have the meanings ascribed to them in the Rights Agreement.


2.            Section 1 of the Rights Agreement is amended
by adding the following paragraph to that section in the appropriate
alphabetical order:


““Convertible
Preferred Shares” shall mean shares of Series A Convertible Participating
Preferred Stock, par value $0.001 per share, of the Company.”


3.             The
definition of “Acquiring Person” set forth in Section 1(a) of the Rights
Agreement is amended by adding the following sentence to the end of that
section:


“Notwithstanding the foregoing, neither Genzyme
Corporation, a Massachusetts corporation (“Parent”), nor Wichita Bio Corporation,
a Delaware corporation and wholly owned subsidiary of Parent (“Purchaser”),
either individually or collectively, shall be or become an Acquiring Person by
reason of (i) the execution and delivery of the Agreement and Plan of Merger,
dated as of May 29, 2007, among Parent, Purchaser and the Company (the “Merger
Agreement”) or any amendment thereto, (ii) the purchase by



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Purchaser of Common Shares or Convertible Preferred Shares pursuant to
(A) a tender offer to acquire all of the issued and outstanding Common Shares
and Convertible Preferred Shares to be commenced by Purchaser pursuant to, and
on the terms and subject to the conditions set forth in, the Merger Agreement
(such tender offer, as it may be amended from time to time, is referred to in
this Agreement as the “Offer”) or (B) an irrevocable option to acquire certain
additional shares of Common Stock directly from the Company, granted by the
Company to Purchaser on the terms and subject to the conditions set forth in
the Merger Agreement (the “Top-Up Option”), (iii) the merger of Purchaser with
and into the Company pursuant to, and on the terms and subject to the
conditions set forth in, the Merger Agreement (the “Merger”), (iv) the
execution and delivery of any tender and voting agreements with certain Company
stockholders (“Principal Shareholders”) or (v) the consummation of any other
transaction contemplated by the Merger Agreement, as it may be amended from
time to time (such actions described in this sentence, the “Permitted Events”).


3.            
The definition of “Shares Acquisition Date” in Section l(p)
of the Rights Agreement is hereby amended by adding the following sentence to
the end of that section:


“Notwithstanding anything else set forth in this
Agreement, a Shares Acquisition Date shall be deemed not to have occurred by
reason of any Permitted Event.”


4.            
Section 3(a) of the Rights Agreement is hereby amended by
adding the following sentence to the end of that section:


“Notwithstanding anything else set forth in this
Agreement, no Distribution Date shall be deemed to have occurred by reason of
any Permitted Event.”


5.            
Section 7(a)(i) of the Rights Agreement is hereby amended to
delete the phrase “(the “Final Expiration Date”)” so that it shall read as
follows:


“(i) the Close of Business on November 29, 2014,”


6.            
Section 7(a) is further amended by replacing the word “or” at
the end of Section 7(a)(ii) with a comma and by adding the following clause
immediately following the word “hereof” in Section 7(a)(iii):


“, or (iv) the moment in time immediately prior to the
Effective Time (as defined in Section 1.4 of the Merger Agreement) (the
earliest to occur of the events described in clauses (i) and (iv) of this
section shall be referred to as the “Final Expiration Date”).”


7.            
Section 11(a)(ii) of the Rights Agreement is hereby amended
by adding the following sentence to the end of that section:


“Notwithstanding anything else set forth in this
Agreement, no event requiring an adjustment under this Section 11(a)(ii) shall
be deemed to have occurred by reason of any Permitted Event.”


8.            
The first phrase of Section 13(c) of the Rights Agreement is
hereby amended to read as follows:


“The Company shall not consummate any such
consolidation (other than the Merger), merger (other than the Merger), sale or
transfer unless the Principal Party shall have a sufficient number of
authorized Common Shares that have not been issued or reserved for issuance to
permit the exercise in full of the Rights in accordance with this Section 13
and unless prior thereto the Company and each Principal Party and each other
Person who may become a Principal Party as a result of such consolidation,
merger, sale or transfer shall have executed and delivered to the Rights Agent
a supplemental agreement providing for the terms set forth in paragraphs (a)
and (b) of this Section 13 and further providing that, as soon as



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practicable after the date of any consolidation, merger, sale or
transfer of assets mentioned in paragraph (a) of this Section 13, the Principal
Party at its own expense will:  . . .”


The remaining portion of
Section 13(c) shall be unchanged and shall remain in full force and effect.


9.         
Section 13(d)(i) of the Rights Agreement is hereby amended to
read as follows:


“(i) consolidate with (other than the Merger),”


10.         
Section 13(d)(ii) of the Rights Agreement is hereby amended
to read as follows:


“(ii) merge with or into (other than by the Merger),”


11.         A new Section 35 is added to read in its
entirety as follows:


“Section
35.  Termination.  Notwithstanding anything herein to the
contrary, immediately prior to the Effective Date, (a) this Agreement shall be
terminated and be without further force or effect, (b) none of the parties to
this Agreement will have any rights, obligations or liabilities hereunder and
(c) the holders of the Rights shall not be entitled to any benefits, rights or
other interests under this Agreement, including, without limitation, the right
to purchase or otherwise acquire Preferred Shares or any other securities of
the Company or of any other Person.”


12.
          The Rights Agreement, as
amended by this Amendment, shall remain in full force and effect in accordance
with its terms.


13.         
All the covenants and provisions of this Amendment by or for
the benefit of the Company or the Rights Agent shall bind and inure to the
benefit of their respective successors and assigns hereunder.


14.         
Nothing in this Amendment shall be construed to give to any
person or corporation other than the Company, the Parent, the Purchaser, the
Rights Agent and the registered holders of the Rights Certificates (and, prior
to the Distribution Date, the Common Stock) any legal or equitable right,
remedy or claim under this Amendment; but this Amendment shall be for the sole
and exclusive benefit of the Company, the Parent, the Purchaser, the Rights
Agent and the registered holders of the Rights Certificates (and, prior to the
Distribution Date, the Common Stock).


15.         
If any term, provision, covenant or restriction of this
Amendment is held by a court of competent jurisdiction or other authority to be
invalid, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions of this Amendment shall remain in full force and
effect and shall in no way be affected, impaired or invalidated.


16.         
This Amendment shall be deemed to be a contract made under
the laws of the State of Delaware and for all purposes shall be governed by and
construed in accordance with the laws of such state applicable to contracts to
be made and performed entirely within such state.


17.         
This Amendment may be executed in any number of counterparts
and each of such counterparts shall for all purposes be deemed to be an original,
and all such counterparts shall together constitute but one and the same
instrument.


18.         
The Company hereby certifies to the Rights Agent that this
Amendment is in compliance with Section 27 of the Rights Agreement.


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IN
WITNESS WHEREOF, the parties herein have caused this
Amendment to be duly executed and attested, all as of the date and year first
above written.


	
  

  	
   

  	
   

  	
   

  	
  BIOENVISION, INC.

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  By:

  	
   

  	
  \s\ David P. Luci

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  	
  Name: David P. Luci

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  	
  Title: Executive Vice President, General Counsel and
  Corporate Secretary

  
	
  Attest:

  	
   

  	
  \s\ James Scibetta

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Name: James Scibetta

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Title:  Chief Financial Officer

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  AMERICAN STOCK TRANSFER & TRUST COMPANY

  
	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  By:

  	
   

  	
  \s\ Herbert J. Lemmer

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  	
  Name: Herbert J. Lemmer

  
	
  Attest:

  	
   

  	
  \s\ Paula Caroppoli

  	
   

  	
   

  	
   

  	
  Title:   Vice President

  
	
   

  	
   

  	
  Name: Paula Caroppoli

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Title:   Vice President

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  



 



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