SC TO-T/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

(Amendment No. 14)

GENZYME CORPORATION

(Name of Subject Company (Issuer))

GC MERGER CORP.

SANOFI-AVENTIS

(Offerors)

(Names of Filing Persons (identifying status as offeror, issuer or other person))

Common Stock, $0.01 par value

(Title of Class of Securities)

372917104

(CUSIP Number of Class of Securities)

Karen Linehan

Senior Vice President Legal Affairs and General Counsel

Sanofi-Aventis

174, avenue de France

75013 Paris, France

Telephone: +33 1 53 77 40 00

(Name, address, and telephone numbers of person authorized to receive

notices and communications on behalf of filing persons)

Copy to:

Michael J. Aiello, Esq.

Weil, Gotshal & Manges LLP

767 Fifth Avenue

New York, NY 10153

(212) 310-8000

CALCULATION OF FILING FEE

Transaction Valuation(1)	Amount of Filing Fee(2)
$18,351,638,353	$1,308,472

(1) Estimated for purposes of calculating the filing fee only. The transaction valuation was calculated by adding: (i) the product of (x) 254,839,847 (the number of shares of common stock of the subject company (“Shares”) issued and outstanding as of July 31, 2010) and (y) $69.00 (the per Share offer price); and (ii) the product of (x) 37,230,306 (the number of Shares issuable upon exercise of outstanding options, warrants and rights as of December 31, 2009) and (y) $20.62 (the difference between the $69.00 per Share offer price and $48.38, the weighted-average exercise price of such options, warrants and rights). The number of outstanding Shares is reported in the subject company’s Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2010, and the number and weighted-average exercise price of the subject company’s options, warrants and rights is reported in the subject company’s Definitive Proxy Statement filed April 26, 2010.

(2) The filing fee was calculated in accordance with Rule 0-11 under the Securities Exchange Act of 1934 by multiplying the transaction value by 0.00007130.

þ Check 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: $1,308,472	Filing Party: Sanofi-Aventis
Form of Registration No.: Schedule TO	Date Filed: October 4, 2010

¨ Check 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:

þ Third-party tender offer subject to Rule 14d-1.

¨ Issuer tender offer subject to Rule 13e-4.

¨ Going-private transaction subject to Rule 13e-3.

¨ Amendment 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.  ¨

This Amendment No. 14 (this “Amendment”) amends and supplements the Tender Offer Statement on Schedule TO filed with the U.S. Securities and Exchange Commission (the “SEC”) on October 4, 2010 (which, together with any amendments and supplements thereto, collectively constitute the “Schedule TO”) and is filed by (i) GC Merger Corp., a Massachusetts corporation (the “Purchaser”), and a wholly-owned subsidiary of Sanofi-Aventis, a French société anonyme (“Parent”) and (ii) Parent. The Schedule TO relates to the offer by the Purchaser to purchase all of the outstanding shares of common stock, $0.01 par value per share (the “Shares”), of Genzyme Corporation, a Massachusetts corporation (“Genzyme”), at a purchase price of $69.00 per Share net to the sellers in cash, without interest thereon and less any required withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase dated October 4, 2010 (which, together with any amendments and supplements thereto, collectively constitute the “Offer to Purchase”) and in the related Letter of Transmittal (which, together with any amendments or supplements thereto, collectively constitute the “Offer”). The Schedule TO (including the Offer to Purchase) contains important information about the Offer, all of which should be read carefully by Genzyme shareholders before any decision is made with respect to the Offer.

Documentation relating to the Offer has been mailed to Genzyme shareholders and may be obtained at no charge at the website maintained by the SEC at www.sec.gov and may also be obtained at no charge by directing a request by mail to MacKenzie Partners, Inc., 105 Madison Avenue, New York, New York 10016, or by calling toll-free at (800) 322-2885.

All information set forth in the Offer to Purchase and the related Letter of Transmittal is incorporated by reference in answer to Items 1 through 12 in the Schedule TO, except those items as to which information is specifically provided herein. Capitalized terms used but not otherwise defined herein shall have the meanings ascribed to such terms in the Offer to Purchase.

Amendments to the Offer to Purchase

Item 12. Exhibits

Item 12 of the Schedule TO is hereby amended by adding the following exhibit thereto:

(a)(5)(O) Excerpt from Investor Presentation by Sanofi-Aventis on February 9, 2011.

SIGNATURE

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

SANOFI-AVENTIS
By:	/s/    ALEXANDRE LEMOALLE
Name:	Alexandre Lemoalle
Title:	Authorized Signatory
GC MERGER CORP.
By:	/s/    KAREN LINEHAN
Name:	Karen Linehan
Title:	Authorized Signatory

Date: February 9, 2011

EXHIBIT INDEX

Exhibit	Exhibit Name
(a)(1)(A)	Offer to Purchase dated October 4, 2010.*
(a)(1)(B)	Letter of Transmittal (including Guidelines for Certification of Taxpayer Identification Number (TIN) on Substitute Form W-9).*
(a)(1)(C)	Notice of Guaranteed Delivery.*
(a)(1)(D)	Letter to Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.*
(a)(1)(E)	Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees.*
(a)(1)(F)	Form of Summary Advertisement as published on October 4, 2010 in The Wall Street Journal.*
(a)(5)(A)	Press Release issued by Sanofi-Aventis on October 4, 2010.*
(a)(5)(B)	English Translation of Excerpts from Offer to Purchase published in France by Sanofi-Aventis on October 4, 2010.*
(a)(5)(C)	Investor Presentation by Sanofi-Aventis dated October 4, 2010.*
(a)(5)(D)	Transcript of Investor Conference Call held by Sanofi-Aventis on October 4, 2010.*
(a)(5)(E)	Press Release issued by Sanofi-Aventis on October 20, 2010.*
(a)(5)(F)	Excerpt from Investor Presentation by Sanofi-Aventis on October 28, 2010.*
(a)(5)(G)	Excerpts of Transcript of Earnings Conference Call held by Sanofi-Aventis on October 28, 2010.*
(a)(5)(H)	Press Release issued by Sanofi-Aventis on November 8, 2010.*
(a)(5)(I)	Press Release issued by Sanofi-Aventis on December 13, 2010.*
(a)(5)(J)	Press Release issued by Sanofi-Aventis on January 9, 2011.*
(a)(5)(K)	Excerpt from Investor Presentation by Sanofi-Aventis on January 11, 2011.*
(a)(5)(L)	Press Release issued by Sanofi-Aventis on January 12, 2011.*
(a)(5)(M)	Press Release issued by Sanofi-Aventis on January 24, 2011.*
(a)(5)(N)	Letter Agreement dated as of January 30, 2011 by and between Sanofi-Aventis and Genzyme Corporation.*
(a)(5)(O)	Excerpt from Investor Presentation by Sanofi-Aventis on February 9, 2011.**
(b)(A)	Facilities Agreement, dated October 2, 2010, by and among Sanofi-Aventis, BNP Paribas, J.P. Morgan plc and Société Générale Corporate & Investment Banking acting as Initial Mandated Lead Arrangers, Société Générale acting as Facilities Agent and the Financial Institutions included as Lenders therein.*
(d)	Not applicable.
(g)	Not applicable.
(h)	Not applicable.

* Previously filed.

** Filed herewith.

EX-99.(A)(5)(O)

Solid financial performance

despite substantial generic competition

Expansion of our unparalleled leadership position in Emerging Markets

Improved CHC

presence with key acquisitions in the U.S. and China

Successful launches of Jevtana

®

in the U.S. and Multaq

®

in EU exceeding

expectations

Ownership of 100% of Merial

and planned new JV with Intervet

Faster achievement of cost saving

targets

Sustained flow of financially disciplined business development

activity

Significant advances in transforming our R&D

approach

Possible acquisition of Genzyme

Delivering on our Strategy

Exhibit (a)(5)(O)

Sanofi-aventis Acquisition of Genzyme

Would Be

Beneficial for Both Parties

Creates new platform for 

sustainable growth further

increasing our biotech exposure

Expands footprint in attractive,

growing rare disease market

Increases our U.S. presence and

expands our R&D pipeline of Phase

II and Phase III products

Meets sanofi-aventis value creation

criteria

Preserves strong capital structure

and financial strength

Provides immediate value for all

shareholders

Captures the potential of

Genzyme’s

business and pipeline

and shifts execution risk to sanofi-

aventis

Enhances Genzyme’s

rare disease

business as a center of excellence

Creates more value for Genzyme’s

other product lines within a larger

company with global reach and

resources

As

has

been

previously

disclosed,

representatives

of

sanofi-aventis

and

Genzyme

have

been

engaged

in

discussions

as

to

the

differences

between

sanofi-aventis’

and

Genzyme’s

perspectives

with

respect

to

the

value

of

Genzyme.

These

discussions

have

included

using

a

potential

Contingent

Value

Right

(CVR)

(with

milestone

payments

based

upon

FDA

approval

and

certain

sales

thresholds)

as

part

of

a

resolution

of

the

parties’

differences

with

respect

to

value.

The

discussions

are

continuing,

and

Genzyme

has

been

sharing

certain

non-public

information

with

sanofi-aventis.

Therefore,

sanofi-

aventis

and

Genzyme

have

executed

a

Non-Disclosure

Agreement

with

respect

to

such

non-public

information.

There

is

no

guarantee

that

these

discussions will

continue or that

the parties will

come to an agreement..

Expanding

Growth

Platforms

in 2011

while Facing More Impact from Generics

No H1N1 sales

U.S. healthcare reform and EU price cuts

Full-year generic impact on Ambien®

CR

and Lovenox®

in the U.S. and Taxotere®

in EU

Uncertainty in the U.S. around generics

of

Taxotere®,

a

2

nd

generic

of

Lovenox®

and

generics

of

Eloxatin®

(1)

Double digit sales growth projected for

our Growth Platforms

(2)

Emerging Markets to grow to 1/3 of

Group sales

Launch of Allegra®

OTC in U.S. and

Jevtana®

in EU

€2bn cost savings by end of 2011

Possible acquisition of Genzyme

(1)

Generic

makers

(Teva,

Fresenius

Kabi

(formerly

Dabur),

Sandoz,

Mayne/Hospira,

MN/Par,

Actavis

and

Sun)

required

to

cease

selling

in

the

U.S. since

June

30,

2010

but

litigation

continues.

(2)

Emerging

Markets,

Diabetes

Brands,

Vaccines,

Consumer

Health

Care,

New

Products

and

Animal

Health

-

Note

that

Animal

Health

sales

are

not

consolidated

and

therefore

not

reflected

in

the

percentages

representing

our

Growth

Platforms.