UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE TO
(Amendment No. 1)

TENDER OFFER STATEMENT

UNDER SECTION 14(D)(1) OR SECTION 13(E)(1) OF THE SECURITIES EXCHANGE ACT OF 1934

BIOENVISION, INC.

(Name Of Subject Company (Issuer))

GENZYME CORPORATION
WICHITA BIO CORPORATION

(Names of Filing Persons (Offerors))

Common Stock, par value $0.001 per share
(including the associated preferred stock purchase rights)
Series A Convertible Participating Preferred Stock, par value $0.001 per share

(Title of Class of Securities)

09059N100

(CUSIP Number of Common Stock)

Peter Wirth
Genzyme Corporation
500 Kendall Street
Cambridge, MA 02142
Telephone: (617) 252-7500

(Name, address and telephone number of person authorized
to receive notices and communications on behalf of filing persons)

with copies to:
Paul Kinsella
Ropes & Gray LLP
One International Place
Boston, Massachusetts 02110
Telephone: (617) 951-7000

CALCULATION OF FILING FEE

Transaction Valuation*	Amount Of Filing Fee**
$371,289,096.20	$11,398.58

*Estimated solely for purposes of calculating amount of filing fee in accordance with Rule 0-11 under the Securities Exchange Act of 1934. The transaction value is based upon the offer to purchase 61,791,222 outstanding shares of Common Stock of Bioenvision, Inc. at a purchase price of $5.60 cash per share and 2,250,000 outstanding shares of Series A Convertible Participating Preferred Stock at a purchase price of $11.20 cash per share, plus any accrued and unpaid dividends. Such number of outstanding shares of Common Stock represents the total of 55,035,740 issued and outstanding shares of Common Stock, outstanding options with respect to 5,973,000 shares of Common Stock and outstanding warrants with respect to 782,482 shares of Common Stock, in each case as of June 1, 2007. Such number of outstanding shares of Series A Convertible Participating Preferred Stock represents all issued and outstanding shares of Series A Convertible Participating Preferred Stock as of June 1, 2007. The transaction value is also based on an estimate of $58,253 accrued and unpaid dividends on Series A Convertible Participating Preferred Stock as of July 2, 2007.

**The amount of filing fee is calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, as amended, and Fee Rate Advisory No. 7 for fiscal year 2007 issued by the Securities and Exchange Commission. Such fee equals 0.00307% of the transaction value.

xCheck the box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number or the Form or Schedule and the date of its filing.

Amount Previously Paid:	$11,398.58
Form or Registration No.:	Schedule TO-T
Filing Party:	Genzyme Corporation
Date Filed:	June 4, 2007

oCheck the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

xthird-party tender offer subject to Rule 14d-1.

oissuer tender offer subject to Rule 13e-4.

ogoing-private transaction subject to Rule 13e-3.

oamendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer:   o

This Amendment No. 1 amends and supplements the Tender Offer Statement on Schedule TO filed with the Securities and Exchange Commission on June 4, 2007 (the “Schedule TO”) relating to a tender offer by Wichita Bio Corporation, a Delaware corporation (the “Offeror”) and a wholly-owned subsidiary of Genzyme Corporation, a Massachusetts corporation (“Parent”), to purchase all the outstanding shares of Common Stock, par value $0.001 per share, including associated preferred stock purchase rights (the “Common Shares”), of Bioenvision, Inc., a Delaware corporation (the “Company”), at a purchase price of $5.60 per Common Share, net to the seller in cash, without interest thereon, less any applicable withholding taxes, and to purchase all outstanding shares of the Company’s Series A Convertible Participating Preferred Stock, par value $0.001 per share (the “Series A Preferred Shares,” and together with the Common Shares, the “Shares”) at a purchase price of $11.20 per Series A Preferred Share, net to the seller in cash, plus all accrued but unpaid dividends, without interest thereon, less any applicable withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase dated June 4, 2007 (the “Offer to Purchase”) and in the related Letter of Transmittal (the “Letter of Transmittal” which, together with the Offer to Purchase, as each may be amended and supplemented from time to time, constitute the “Offer”).

Capitalized terms used herein and not defined herein have the respective meanings assigned such terms in the Offer to Purchase and the Schedule TO.

ITEM 4.TERMS OF THE TRANSACTION

Section 5 of the Offer to Purchase, “Certain U.S. Federal Income Tax Consequences” is deleted and replaced by the following:

“5.   Material U.S. Federal Income Tax Consequences

The following is a general summary of certain U.S. federal income tax consequences relevant to a stockholder whose Shares are (1) tendered and purchased for cash pursuant to the Offer or (2) converted to cash in the Merger. This discussion is for general information only and does not purport to consider all aspects of United States federal income taxation that may be relevant to stockholders. The summary is based on the current provisions of the Internal Revenue Code of 1986, as amended (the “Code”), regulations issued thereunder, judicial decisions and administrative rulings, all of which are subject to change, possibly with retroactive effect. The tax consequences to any particular stockholder may differ depending on that stockholder’s own circumstances and tax position. For example, the following general summary may not be applicable with respect to Shares received pursuant to the exercise of employee stock options or otherwise as compensation or with respect to holders of Shares who are subject to special tax treatment under the Code such as life insurance companies, tax-exempt organizations, financial institutions, S corporations, partnerships and other pass-through entities, trusts, shareholders liable for the alternative minimum tax, dealers in securities or currencies, traders who elect to apply a mark-to-market method of accounting, U.S. expatriates and persons who are holding Shares as part of a straddle, conversion, constructive sale, hedge or hedging or other integrated transaction. This discussion is also not applicable to Shares held by partnerships (or other entities or arrangements that are classified as partnerships for U.S. federal income tax purposes). If a partnership holds Shares, the tax treatment of a partner in the partnership will generally depend on the status of the partner and the activities of the partnership. If you are a partnership or a partner in a partnership holding Shares, you should consult your tax advisors. This discussion assumes that the Shares are held as “capital assets” within the meaning of Section 1221 of the Code. This discussion does not address estate or gift tax or the consequences of the transactions described herein under the tax laws of any state, local or foreign jurisdiction. Stockholders are urged to consult their own tax advisors to determine the particular tax consequences to them (including the application and effect of any state, local or foreign income and other tax laws) of the Offer and the Merger.

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U.S. Stockholders.   The following is applicable to stockholders that are United States persons for U.S. federal income tax purposes (“U.S. Stockholders”). U.S. Stockholders include stockholders that are citizens or residents of the United States, corporations, partnerships or other entities created or organized under the laws of the United States or any political subdivision thereof, certain trusts whose administration is subject to the primary supervision of a United States court and which has one or more United States persons who have authority to control all of its substantial decisions or which has elected to be treated as a United States person, and estates that are subject to United States federal income taxation regardless of the source of their income.

The receipt of cash pursuant to the Offer or the Merger will be a taxable transaction for U.S. federal income tax purposes.

Generally, for U.S. federal income tax purposes, a tendering stockholder or a stockholder who receives cash in exchange for Shares in the Merger will recognize gain or loss equal to the difference between the amount of cash received by the stockholder pursuant to the Offer or Merger and the adjusted tax basis in the Shares tendered by the stockholder and purchased pursuant to the Offer or converted into cash in the Merger, as the case may be. Gain or loss will be calculated separately for each block of Shares tendered and purchased pursuant to the Offer or converted into cash in the Merger, as the case may be. Any gain or loss recognized by such stockholder will be capital gain or loss. Any capital gain or loss will be long-term capital gain or loss if such stockholder’s holding period for the Shares exceeds one year. In the case of non-corporate stockholders, long-term capital gains are currently eligible for reduced rates of taxation. The ability to use capital losses to offset ordinary income is limited.

Non-U.S. Stockholders.   The following is applicable to stockholders that are not U.S. Stockholders (such stockholders, “Non-U.S. Stockholders”).

Any gain realized on the receipt of cash in pursuant to the Offer or the Merger by a Non-U.S. Stockholder generally will not be subject to United States federal income tax unless:

·the gain is effectively connected with a trade or business of the Non-U.S. Stockholder in the United States (or, if required by an applicable income tax treaty, is attributable to a United States permanent establishment of the Non-U.S. Stockholder); or

·in the case of a non-resident alien, the individual is present in the United States for 183 days or more in the taxable year of that disposition, and certain other conditions are met.

An individual Non-U.S. Stockholder described in the first bullet point above generally will be subject to United States federal income tax on the net gain derived from the Offer or the Merger under regular graduated U.S. federal income tax rates. If a Non-U.S. Stockholder that is a foreign corporation falls under the first bullet point above, it generally will be subject to tax on its net gain in the same manner as if it were a U.S. person as defined under the Code and, in addition, may be subject to a branch profits tax equal to 30% of its effectively connected income (or at such lower rate as may be specified by an applicable income tax treaty). An individual Non-U.S. Stockholder described in the second bullet point immediately above will be subject to a flat 30% tax (or at such lower rate as may be specified by an applicable income tax treaty) on the gain derived from the Offer or the Merger, which may be offset by U.S. source capital losses, even though the individual is not considered a resident of the United States.

Backup Withholding.   A stockholder (other than certain exempt stockholders including, among others, all corporations) that tenders Shares may be subject to a 28% backup withholding tax, unless the stockholder provides its TIN and certifies that such number is correct, provides certain other certifications, and otherwise complies with the applicable requirements of the backup withholding rules. A stockholder that does not furnish a required TIN or that does not otherwise establish a basis for an exemption from backup withholding may also be subject to a penalty imposed by the IRS. See “Backup Withholding” under Section 2. Each U.S. stockholder should complete and sign the Substitute Form W-9 included as part of

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the Letter of Transmittal so as to provide the information and certification necessary to avoid backup withholding. Non-U.S. stockholders should complete the appropriate Form W-8. See Instruction 9 to the Letter of Transmittal.

If backup withholding applies to a stockholder, the Depositary is required to withhold 28% from payments to such stockholder and the IRS may impose a penalty on such stockholder. Backup withholding is not an additional tax. Rather, the amount of the backup withholding can be credited against the U.S. federal income tax liability of the person subject to the backup withholding, provided that the required information is given to the IRS. If backup withholding results in an overpayment of tax, a refund can be obtained by the stockholder by filing a U.S. federal income tax return.”

ITEM 11.ADDITIONAL INFORMATION

Item 11(a)(5) is hereby amended by replacing “None.” with the following paragraph:

“On June 7, 2007, three purported shareholders of the Company filed a purported class action lawsuit in the Court of Chancery in the State of Delaware, New Castle County docketed as Trombley, et al. v. Bioenvision, Inc., et al., Civ. A. No. 3008 (the “Action”) against the Company, each of its directors, the Parent and the Offeror. The Action purports to be brought individually and on behalf of all holders of Common Shares. The Action alleges that the Company director defendants breached their fiduciary duties to the Company’s shareholders in connection with the Offer and that the Parent and Offeror aided and abetted such alleged breach of the Company director defendants’ fiduciary duties. Based on these allegations, the Action seeks, among other relief, injunctive relief preliminarily and permanently enjoining each of the Company, its directors, the Parent and the Offeror from consummating the Offer and the Merger, directing the Company director defendants to exercise their fiduciary duties to obtain a Merger or any of the terms thereof. A copy of the complaint in the Action is included hereto as Exhibit (a)(5)(D) and is hereby incorporated herein by reference. The foregoing description is qualified in its entirety by reference to Exhibit (a)(5)(D).”

ITEM 12.EXHIBITS

(a)(1)(A)	Offer to Purchase for Cash dated June 4, 2007.*
(a)(1)(B)	Form of Letter of Transmittal.*
(a)(1)(C)	Form of Notice of Guaranteed Delivery.*
(a)(1)(D)	Form of Letter to Brokers, Dealers, Banks, Trust Companies and Other Nominees.*
(a)(1)(E)	Form of Letter to Clients for Use by Brokers, Dealers, Banks, Trust Companies and Other Nominees.*
(a)(1)(F)	Form of Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9.*
(a)(2)	None.
(a)(3)	None.
(a)(4)	None.
(a)(5)(A)	Joint Press Release issued by Genzyme Corporation and Bioenvision, Inc. dated May 29, 2007 (incorporated herein by reference to Exhibit 99.1 to the Current Report on Form 8-K filed by Genzyme Corporation on May 29, 2007).*

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(a)(5)(B)	Transcript of Conference Call held by Genzyme Corporation and Bioenvision, Inc. on May 29, 2007 (incorporated herein by reference to the Tender Offer Statement on Schedule TO filed by Genzyme Corporation on May 29, 2007).*
(a)(5)(C)	Summary Advertisement published in the Wall Street Journal on June 4, 2007.*
(a)(5)(D)	Complaint filed by Brian Trombley, Dan J. Thomas, Jr. and John Hawn, on behalf of themselves and all other public shareholders of Bioenvision, Inc., on June 7, 2007, in the Court of Chancery in the State of Delaware, New Castle County (incorporated herein by reference to Amendment No. 1 to the Solicitation/Recommendation Statement on Schedule 14D-9 filed by Bioenvision, Inc. on June 12, 2007).
(b)	None.
(d)(1)	Agreement and Plan of Merger, dated as of May 29, 2007, by and between Genzyme Corporation, Wichita Bio Corporation and Bioenvision, Inc. (incorporated herein by reference to Exhibit 2.1 to the Current Report on Form 8-K filed by Genzyme Corporation on May 29, 2007).*
(d)(2)	Form of Tender and Voting Agreement, dated as of May 29, 2007, by and between Genzyme Corporation, Wichita Bio Corporation and certain shareholders of Bioenvision, Inc. (incorporated herein by reference to Annex II to Exhibit 2.1 to the Current Report on Form 8-K filed by Genzyme Corporation on May 29, 2007).*
(d)(3)	Confidentiality Agreement, dated as of April 24, 2007 by and between Genzyme Corporation and Bioenvision, Inc.*
(d)(4)	Co-Development Agreement, dated as of March 21, 2001, by and among Genzyme Corporation (originally Ilex Oncology, Inc.) and Bioenvision, Inc. (incorporated herein by reference to Exhibit 10.28 to the Current Report on Form 8-K filed by Bioenvision, Inc. on June 24, 2002).*
(d)(5)	Letter Agreement for Co-Development of an Oral Clofarabine Formulation and First Amendment to Co-Development Agreement, dated September 2, 2003, by and between Genzyme Corporation and Bioenvision, Inc. (incorporated herein by reference to Exhibit 10.28 to the Annual Report on Form 10-KSB filed by Bioenvision, Inc. on October 13, 2005).*
(d)(6)	Amendment No. 2 to the Co-Development Agreement, dated December 31, 2003, by and between Genzyme Corporation and Bioenvision, Inc. (incorporated herein by reference to Exhibit 10.26 to the Annual Report on Form 10-KSB filed by Bioenvision, Inc. on October 13, 2005).*
(g)	None.
(h)	None.

*Previously filed.

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SIGNATURES

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

	GENZYME CORPORATION
Dated: June 13, 2007	By:	/s/ EARL M. COLLIER, JR.
	Name:		Earl M. Collier, Jr.
	Title:		Executive Vice President
	WICHITA BIO CORPORATION
Dated: June 13, 2007	By:	/s/	EARL M. COLLIER, JR.
	Name:		Earl M. Collier, Jr.
	Title:		President

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EXHIBIT INDEX

EXHIBIT NUMBER	DOCUMENT
(a)(1)(A)	Offer to Purchase for Cash dated June 4, 2007.*
(a)(1)(B)	Form of Letter of Transmittal.*
(a)(1)(C)	Form of Notice of Guaranteed Delivery.*
(a)(1)(D)	Form of Letter to Brokers, Dealers, Banks, Trust Companies and Other Nominees.*
(a)(1)(E)	Form of Letter to Clients for Use by Brokers, Dealers, Banks, Trust Companies and Other Nominees.*
(a)(1)(F)	Form of Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9.*
(a)(2)	None.
(a)(3)	None.
(a)(4)	None.
(a)(5)(A)	Joint Press Release issued by Genzyme Corporation and Bioenvision, Inc. dated May 29, 2007 (incorporated herein by reference to Exhibit 99.1 to the Current Report on Form 8-K filed by Genzyme Corporation on May 29, 2007).*
(a)(5)(B)	Transcript of Conference Call held by Genzyme Corporation and Bioenvision, Inc. on May 29, 2007 (incorporated herein by reference to the Tender Offer Statement on Schedule TO filed by Genzyme Corporation on May 29, 2007).*
(a)(5)(C)	Summary Advertisement published in the Wall Street Journal on June 4, 2007.*
(a)(5)(D)	Complaint filed by Brian Trombley, Dan J. Thomas, Jr. and John Hawn, on behalf of themselves and all other public shareholders of Bioenvision, Inc., on June 7, 2007, in the Court of Chancery in the State of Delaware, New Castle County (incorporated herein by reference to Amendment No. 1 to the Solicitation/Recommendation Statement on Schedule 14D-9 filed by Bioenvision, Inc. on June 12, 2007).
(b)	None.
(d)(1)	Agreement and Plan of Merger, dated as of May 29, 2007, by and between Genzyme Corporation, Wichita Bio Corporation and Bioenvision, Inc. (incorporated herein by reference to Exhibit 2.1 to the Current Report on Form 8-K filed by Genzyme Corporation on May 29, 2007).*
(d)(2)	Form of Tender and Voting Agreement, dated as of May 29, 2007, by and between Genzyme Corporation, Wichita Bio Corporation and certain shareholders of Bioenvision, Inc. (incorporated herein by reference to Annex II to Exhibit 2.1 to the Current Report on Form 8-K filed by Genzyme Corporation on May 29, 2007).*
(d)(3)	Confidentiality Agreement, dated as of April 24, 2007 by and between Genzyme Corporation and Bioenvision, Inc.*
(d)(4)	Co-Development Agreement, dated as of March 21, 2001, by and among Genzyme Corporation (originally Ilex Oncology, Inc.) and Bioenvision, Inc. (incorporated herein by reference to Exhibit 10.28 to the Current Report on Form 8-K filed by Bioenvision, Inc. on June 24, 2002).*

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(d)(5)	Letter Agreement for Co-Development of an Oral Clofarabine Formulation and First Amendment to Co-Development Agreement, dated September 2, 2003, by and between Genzyme Corporation and Bioenvision, Inc. (incorporated herein by reference to Exhibit 10.28 to the Annual Report on Form 10-KSB filed by Bioenvision, Inc. on October 13, 2005).*
(d)(6)	Amendment No. 2 to the Co-Development Agreement, dated December 31, 2003, by and between Genzyme Corporation and Bioenvision, Inc. (incorporated herein by reference to Exhibit 10.26 to the Annual Report on Form 10-KSB filed by Bioenvision, Inc. on October 13, 2005).*
(g)	None.
(h)	None.

*Previously filed.

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