SC 14D9/A

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14D-9

SOLICITATION/RECOMMENDATION STATEMENT
PURSUANT TO SECTION 14(d)(4) OF THE
SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

GENZYME CORPORATION

(Name of Subject Company)

GENZYME CORPORATION

(Name of Person(s) Filing Statement)

Common Stock, par value $0.01 per share
(Title of Class of Securities)

372917104
(CUSIP Number of Common Stock)

Peter Wirth
Executive Vice President
Genzyme Corporation
500 Kendall Street
Cambridge, Massachusetts 02142
(617) 252-7500
(Name, Address and Telephone Number of Person Authorized to Receive Notices
and Communications on Behalf of the Person(s) Filing Statement)

With copies to:

Paul M. Kinsella	Andrew R. Brownstein
Ropes & Gray LLP	Wachtell, Lipton, Rosen & Katz
Prudential Tower	51 West 52nd St
800 Boylston Street	New York, New York 10019
Boston, Massachusetts 02199	(212) 403-1000
(617) 951-7000

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

TABLE OF CONTENTS

	Item 9. Exhibits
SIGNATURE
Ex-(a)(14)
Ex-(a)(15)

This Amendment No. 2 amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 originally filed by Genzyme Corporation, a Massachusetts corporation (the “Company” or “Genzyme”), with the Securities and Exchange Commission (the “SEC”) on October 7, 2010 (as previously amended, the “Schedule 14D-9”), relating to the unsolicited tender offer by GC Merger Corp., a Massachusetts corporation (“Offeror”) and wholly-owned subsidiary of Sanofi-Aventis, a French société anonyme (“Sanofi”), to purchase all of the outstanding shares of the Company’s common stock, par value $.01 per share (the “Shares”), at a purchase price of $69.00 per Share (the “Offer Price”), net to the selling shareholders 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 (the “Offer to Purchase”), and in the related Letter of Transmittal (which, together with the Offer to Purchase, constitutes the “Offer”), included as Exhibits (a)(1)(A) and (a)(1)(B) to the Tender Offer Statement on Schedule TO (as amended or supplemented from time to time, the “Schedule TO”) filed by Sanofi and Offeror with the SEC on October 4, 2010.

Item 9. Exhibits.

Item 9 of the Schedule 14D-9 is hereby amended and supplemented by adding the following thereto:

Exhibit No.	Description
(a)(14)	Press Release issued by Genzyme, dated October 14, 2010.
(a)(15)	European Committee for Treatment and Research in Multiple Sclerosis Investor Presentation, dated October 14, 2010.

SIGNATURE

     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.

Dated: October 14, 2010	GENZYME CORPORATION
	By:	/s/ Peter Wirth
	Name:   Peter Wirth
	Title:   Executive Vice President

EX-99.(A)(14)

Exhibit (a)(14)

For Immediate Release	Media Contact:	Investor Contact:
October 14, 2010	John Lacey	Patrick Flanigan
	(617) 768-6690	(617)
	768-6563	lohn.laceyna

Genzyme’s Alemtuzumab Shows Sustained Reduction in Relapses and Disability
in Five-Year Review of MS Patients from Phase 2 Trial

Significant Benefit Observed for Patients with Highly Active MS on
Alemtuzumab—Similar to Overall Alemtuzumab-Cohort

Data Reported at ECTRIMS International Conference

CAMBRIDGE, Mass. —Genzyme Corporation (Nasdaq: GENZ) today reported five-year patient data from its completed Phase 2 multiple sclerosis (MS) trial. This sub-group analysis found that nearly 90 percent of alemtuzumab-treated patients were free of sustained accumulation of disability, and that patients receiving alemtuzumab also maintained improved mean disability scores and a low risk of relapse over the 60-month follow-up period. The majority of alemtuzumab patients received their last course of treatment at month 12 in the study. These accumulated efficacy and safety data were presented in Sweden at the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) annual meeting, one of the largest annual international MS conferences.

The CAMMS223 Phase 2 trial, first reported in the New England Journal of Medicine in 2008, compared alemtuzumab to the approved MS therapy Rebif® (high dose interferon beta-la) in early, active, relapsing-remitting multiple sclerosis (RRMS) patients who had received no prior therapy. In the trial, alemtuzumab was given to patients in two or three annual cycles of not more than five days per cycle, while Rebif was given to patients three times per week, every week for three years.

Results at 60 months of patient follow-up found that:

• Alemtuzumab-treated patients demonstrated consistently lower annualized relapse rates over the entire observation period compared to those treated with Rebif. Annualized relapse rate was 0.11 in those receiving alemtuzumab, compared with 0.35 in patients receiving Rebif.

• The mean disability (EDSS) score for patients receiving alemtuzumab improved, but worsened for patients receiving Rebif.

• Over the 60-month study period, 13 percent of patients receiving alemtuzumab experienced a sustained increase in disability compared with 38 percent of patients taking Rebif.

“These long-term patient follow-up data suggest that alemtuzumab may have a significant disease modifying effect in patients with early, active, relapsing-remitting multiple sclerosis,” said Alasdair Coles, MD, Senior Lecturer, Department of Clinical Neurosciences, University of Cambridge, a lead investigator of the Phase 2 clinical trial and author of the 5-year review abstract.

“We appreciate the tremendous dedication of the patients, physicians, and nurses participating in this important trial, who enabled us to obtain these five-year data,” said Mark Enyedy, Genzyme president for Transplant, Oncology and Multiple Sclerosis. “Their efforts have provided further insights into the potential of alemtuzumab to improve long-term outcomes for patients with multiple sclerosis.” The CAMMS223 Phase 2 trial was larger and follow-up was longer than the typical Phase 2 MS trial.

Strong Benefit Seen in Patients with Highly Active Multiple Sclerosis

A second abstract presented at ECTRIMS found that patients in the Phase 2 trial with highly active RRMS had a significantly decreased annualized relapse rate when receiving alemtuzumab compared to Rebif.

Results at 36-months of patient follow-up found that:

• Annualized relapse rate was significantly reduced for patients receiving alemtuzumab. Annualized relapse rate was 0.09 in patients receiving alemtuzumab as compared with 0.47 in those receiving Rebif, a reduction of 81 percent.

• 91 percent of alemtuzumab-treated patients were free of sustained accumulation of disability, compared to 75 percent of patients taking Rebif.

More than half of the patients enrolled in the Phase 2 trial had highly active RRMS: 56 percent of alemtuzumab treated patients, and 55 percent of Rebif treated patients. Patients with highly active disease had at least two relapses in the year prior to treatment in the trial, and had at least one gadolinium enhancing brain lesion identified through magnetic resonance imaging (MRI).

“In this Phase 2 trial, alemtuzumab was significantly more effective than Rebif at reducing relapses and the accumulation of disability in patients with highly active disease, a population at a typically higher risk for poor MS outcomes,” said Dean Wingerchuk, M.D., Department of Neurology, Mayo Clinic.

Genzyme is conducting two pivotal Phase 3 trials to evaluate alemtuzumab in the treatment of MS. CARE-MS I, a randomized trial comparing alemtuzumab to Rebif, is studying early, active RRMS patients who have received no prior therapy. CARE-MS II, which also compares alemtuzumab to Rebif, is studying RRMS patients who relapsed while on other MS therapies. Data from the Phase 3 trials are expected to be available in 2011.

Alemtuzumab is an investigational drug for the treatment of MS and must not be used in MS patients outside of a formal, regulated clinical trial setting in which appropriate patient monitoring measures are in place.

About CAMMS223 Phase 2 Study

In the Phase 2 trial, 334 patients with active RRMS were randomized to treatment with alemtuzumab at one of two dose levels, or Rebif. The majority of patients last received alemtuzumab at Month 12. Patients were strongly encouraged to continue for two additional years of follow-up beyond the original three years of the study.

Sixty-eight percent of alemtuzumab patients participated in the follow-up program, and 60 percent were evaluated at 60 months. Forty-two percent of Rebif patients participated in the follow-up program, and 35 percent were evaluated at 60 months. Rater-blinded disability scores were assessed quarterly and relapses as-needed. A sensitivity analysis adjusted for patients receiving alternative disease-modifying therapy during the follow-up period, as well as for retreatment with alemtuzumab.

Safety Information

The five-year data review confirmed what has been previously reported. The common adverse events in the trial included infusion-associated reactions in the alemtuzumab patients and flu-like symptoms and injection site reactions in patients using Rebif. Alemtuzumab-treated patients were more likely than Rebif patients to experience infections, particularly of the upper respiratory tract; infections were predominantly mild to moderate in severity and there were no life-threatening or fatal infections.

As described previously, immune thrombocytopenic purpura (ITP), an autoimmune disease, was identified in six alemtuzumab treated patients and one Rebif patient in the Phase 2 trial. Symptoms of ITP went unrecognized in the first alemtuzumab case and led to the onset of a fatal cerebral hemorrhage. In the other five alemtuzumab-related cases, with timely diagnosis and treatment if needed, all 5 achieved durable remission of ITP.

Approximately 30 percent of alemtuzumab-treated patients developed an autoimmune thyroid-related adverse event. Thyroid disorders either normalized spontaneously or were managed using conventional therapies. One alemtuzumab-treated patient was identified through renal monitoring at month 51 to have anti-glomerular basement membrane (anti-GBM) disease, an autoimmune kidney disease. The patient was successfully treated and is in remission. Patients who experienced an autoimmune adverse event, including ITP, experienced improved control of their MS consistent with alemtuzumab’s effect in the overall study population. Patient monitoring for thyroid disorders, ITP, and anti-GBM disease is incorporated into all Genzyme-sponsored trials of alemtuzumab for the investigational treatment of MS.

Conference Call Information

A conference call and WebEx have been scheduled for today at 12:30 p.m. EST, to review the five-year patient follow-up data from Genzyme’s completed Phase 2 multiple sclerosis (MS) trial. To participate in the call, please dial 312-470-7406 and refer to pass code “Genzyme.” Instructions for the WebEx can be found on the investor events section of www.genzyme.com. Replays of the call will be available by dialing 402-998-1620 until October 22 at 11:59 p.m. EST.

About Genzyme

One of the world’s leading biotechnology companies, Genzyme is dedicated to making a major positive impact on the lives of people with serious diseases. Since 1981, the company has grown from a small start-up to a diversified enterprise with more than 12,000 employees in locations spanning the globe and 2009 revenues of $4.5 billion. In 2010, Genzyme was named to the Fortune 500.

With many established products and services helping patients in 100 countries, Genzyme is a leader in the effort to develop and apply the most advanced technologies in the life sciences. The company’s products and services are focused on rare inherited disorders, kidney disease, orthopaedics, cancer, transplant, and immune disease. Genzyme’s commitment to innovation continues today with a substantial development program focused on these fields, as well as cardiovascular disease, neurodegenerative diseases, and other areas of unmet medical need.

This press release contains forward-looking statements regarding Genzyme’s future plans and business strategies, including: its expectations about when data will become available from the two phase 3 trials and the success of alemtuzumab to treat MS. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected in these forward-looking statements, including: the timing and outcome of the data from the phase 3 trials; the timing and outcome of discussions with the regulatory agencies regarding approval of alemtuzumab for MS; the actual safety and efficacy of alemtuzumab for MS; and the risks and uncertainties described in reports filed by Genzyme with the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended, including without limitation the information under the heading “Risk Factors” in Genzyme’s Quarterly Report on Form 10-Q for the quarter ending June 30, 2010. Genzyme cautions investors not to place substantial reliance on the forward-looking statements contained in this press release. These statements speak only as of the date of this press release, and Genzyme undertakes no obligation to update or revise these statements.

Genzyme®, Campath®, and MabCampath® are registered trademarks and CARE-MS is a service mark of Genzyme Corporation. All rights reserved. Rebif® is a registered trademark of EMD Serono, Inc. or affiliates.

Genzyme’s press releases and other company information are available at www.genzyme.com and by calling Genzyme’s investor information line at 1-800-9054369 within the United States or 1-678-999-4572 outside the United States.

EX-99.(A)(15)

Exhibit (a)(15)

ECTRIMS Investor Presentation October 14, 2010

Forward-Looking Statements Disclaimer This presentation contains forward-looking statements including, without limitation, Genzyme's: expectation that the Phase 3 data for alemtuzumab-MS will be available in mid-011; conclusion that alemtuzumab-MS offers a potentially transformative approach to MS treatment with unprecedented efficacy; and conclusion that alemtuzumab-MS has a manageable safety profile. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those forecasted. These risks and uncertainties include, among others: that Genzyme is not able to successfully complete clinical development and obtain regulatory approvals of alemtuzumab-MS within expected timeframes or at all; that ITP, thyroid disease, Goodpasture's disease, any other antibody-mediated autoimmunity issues, or any other safety issues, increase in frequency or severity in the treated population; that Genzyme is unable to effective compete against current or development-stage MS products due to price, safety profile, or any other reason; that Genzyme has not accurately estimated the size and characteristics of the market to be addressed by alemtuzumab-MS; that Genzyme is unable to secure the amount of reimbursement coverage from third-party payors that it expects; that physicians do not adopt alemtuzumab-MS as a treatment option at the rates that Genzyme estimates; and the risks and uncertainties described in Genzyme's SEC reports filed under the Securities Exchange Act of 1934, including the factors discussed under the caption "Risk Factors" in Genzyme's Quarterly Report on Form 10-Q for the quarter ended June 30, 2010. Genzyme cautions investors not to place substantial reliance on the forward-looking statements contained in this presentation. These statements speak only as of today's date and Genzyme undertakes no obligation to update or revise them.

Agenda Introduction: Mark Enyedy, President Transplant, Oncology and Multiple Sclerosis Phase 2 data review: Michael Panzara, VP MS & Immune Diseases Patient perspective: Alastair Compston, Professor of Neurology and the head of the Department of Clinical Neurosciences, University of Cambridge, United Kingdom Alasdair Coles, MD, Senior Lecturer, Department of Clinical Neurosciences, University of Cambridge Q&A moderator: Mark Enyedy

A Promising New Standard of Care for MS Efficacy Superior to Rebif in Phase 2 study Improvement in disability Durability >70% of patients free from clinically active disease at 5 years Convenience Annual dosing Safety and Tolerability Manageable profile Potential new standard of care for an estimated $14B market in 2012* *Cowen Report, March 2010

Alemtuzumab Overview Humanized monoclonal antibody Targets CD52 reducing circulating B and T lymphocytes 10 poster presentations at ECTRIMS 2010 Large active comparator phase 2 complete follow-up: 5 year efficacy, up to 7.5 years safety Human IgG1 Rat CDRs

6 Phase 3 Data Expected Beginning in Mid-11 Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis CARE-MS I CARE-MS II Patients 581 840 Study Duration 2 years 2 years Patient Population Treatment-naive RRMS Onset within 5 yrs EDSS ^ 3.0 Treatment-experienced RRMS Onset within 10 yrs EDSS ^ 5.0 Treatment Arms Alemtuzumab 12 mg IFNB -1a 44 mcg 3x/week Alemtuzumab 12 mg Alemtuzumab 24 mg IFNB -1a 44 mcg 3x/week Randomization 2 : 1 2 : 2 : 1 Co-primary Outcomes Relapse Rate Disability Progression Relapse Rate Disability Progression Blinding Rater-blinded Rater-blinded

October 14, 2010 Phase 2 Data Review Michael Panzara

Emerging Profile Shows Unprecedented Efficacy Alemtuzumab vs. Interferon Beta-1a in Early Multiple Sclerosis N Engl J Med 359:1786, October 23, 2008 Original Article

Phase 2, randomized, open label, comparator-controlled, rater-blinded trial 334 treatment-naive patients with early, active relapsing-remitting MS (RRMS) Baseline Early Active MS: EDSS ^3, disease duration ^3 years Primary endpoints: Relapse rate and time to sustained accumulation of disability (SAD) by EDSS Note: All treatment arms received 1g methylprednisolone QDx3 at months 0, 12, and 24. Phase 2 Study Design IFN^-1a 44 µg 3x/wk SC Alemtuzumab 12 mg daily IV Alemtuzumab 24 mg daily IV 107 102 101 108 105 104 108 QDx3 QDx5 QDx3 QDx5 95 80 0 12 24 36 Extension phase Study duration (months) 24 77 22 82 66 92 92 2002 2010

Baseline Characteristics: Early, Active RRMS 1. Coles et al. N Engl J Med. 2008. 2. Coles et al. AAN. 2008. IFN^-1a N=111 Alemtuzumab 12 mg/day N=112 Alemtuzumab 24 mg/day N=110 Years of Age mean +- SD 32.8 +- 8.8 31.9 +- 8.0 32.2 +- 8.8 Gender % Female 64.0 64.3 64.5 EDSS Score mean +- SD 1.9 +- 0.8 1.9 +- 0.7 2.0 +- 0.7 Time Since First Relapse median (range) 1.4 (0.2, 6.3) 1.3 (0.1, 3.5) 1.2 (0.3, 3.2) Number Relapses in Past 2 Years mean (range)1 2.3 (1, 6) 2.4 (0, 6) 2.3 (0, 7) Baseline Characteristics Were Balanced Across Treatment Groups

Effects on Relapse Rate Sustained Over 5 Years P<0.0001 P<0.001 1. CAMMS223 Trial Investigators. N Engl J Med. 2008. 2. Coles et al. ECTRIMS 2009. 3. Coles et al. ECTRIMS 2010. SC IFN^-1a Alemtuzumab Pooled Effects on Relapse Rate Sustained Over 5 Years 0.36 0.34 0.35 0.10 0.10 0.11 0.0 0.1 0.2 0.3 0.4 0.5 Months 0-361 Months 0-482 Months 0-603 Annualized Relapse Rate P<0.0001

Reduction in Disability Progression Sustained Over 5 Years 26 32 38 9 9 13 0 5 10 15 20 25 30 35 40 45 50 55 Months 0-361 Months 0-482 Months 0-603 Percent of Patients With SAD (6-mo. Criteria) P<0.001 P<0.0001 SC IFN^-1a Alemtuzumab Pooled 1. CAMMS223 Trial Investigators. N Engl J Med. 2008. 2. Coles et al. ECTRIMS 2009. 3. Coles et al. ECTRIMS 2010. P<0.0001

P<0.0001 SC IFN^-1a Alemtuzumab Pooled Improved Disability Scores Sustained Over 5 Years 1. CAMMS223 Trial Investigators. N Engl J Med. 2008. 2. Coles et al. ECTRIMS 2009. 3. Coles et al. ECTRIMS 2010. Month 361 Month 482 Month 603 Worsened Improved P=0.0002 P<0.001

Safety Profile: Detectable, Manageable, Treatable Mild to moderate infusion reactions Pretreatment at time of infusion annually can effectively prevent/ameliorate symptoms Infections predominantly mild to moderate in severity No life-threatening or fatal infections Responded appropriately to conventional treatment No increased risk with repeated cycles Antibody-mediated autoimmunity ITP, thyroid disorders, Goodpasture's disease Methods to monitor and detect readily available Effectively managed when detected early Risk minimization program to maximize patient outcomes in place Patient and physician education, questionnaires Routine blood and urine testing As of September, Safety Monitoring Committee for Phase 3 have highlighted no new signals Coles, et al., J Neurol 2006; Coles, et al., NEJM 2008; Clatworthy, et al., NEJM 2008; Kahn et al., AAN 2010

Autoimmune-related Thyroid Disease Seen in approximately 30% of alemtuzumab treated patients No patient with a thyroid event discontinued alemtuzumab treatment in phase 2 Detected through periodic testing, signs and symptoms Most events managed by conventional oral medications E.g., levothyroxine (hypothyroidism), methimazole (hyperthyroidism)

Immune Thrombocytopenic Purpura (ITP) < 3% alemtuzumab-treated patients in phase 2 Index case in 2005 went unrecognized leading to intracerebral hemorrhage Remaining cases: Identified through routine monitoring and managed with medical treatment or close observation Achieved durable remission with normal platelet counts and no sequelae Patient and physician education, monthly questionnaires and monthly CBC in place to allow early detection and intervention

Anti-GBM Disease (Goodpasture's) Rare event in alemtuzumab treated patients 1 event observed in phase 2 study, two reported outside of sponsored studies Early detection led to early intervention and recovery Patient in trial identified early, treated, recovered with near-normal renal function Alemtuzumab experience consistent with literature indicating early detection and treatment improves survival, prevents renal failure Levy et al., 2001 100% survival, 95% preserved renal function at 1 year when detected and treated when serum creatinine < 500 mmol/L (5.7 mg/dL) Treatment = short term plasma exchange, cyclophosphamide, methyprednisolone Education and surveillance in Genzyme-sponsored trials focuses on education, early detection to improve outcome Monthly serum creatinine testing, urinalysis Levy et al., Ann Intern Med 200111

Patients With Secondary Autoimmune Disorders Experienced Efficacy Similar to Overall Cohort Secondary autoimmune events through 36 months: 47 patients (43 thyroid, 4 ITP) 78% reduced rate of relapse vs IFN^-1a (P<0.0001) Brinar et al. AAN. 2010. 66% P=0.031 Kaplan-Meier Analysis Time Disability Accumulation SC IFN^-1a Alemtuzumab Pooled Percent of Patients With Sustained Accumulation of Disability

October 14, 2010 Patient Perspective Alasdair Coles, MD

Freedom From: Patients Emphasize Freedom from Disease Burden "Three years after I received my first series of doses, I woke up one morning and I almost, for a short period of time, forgot that I had MS." D.G., US Phase 2 Trial Patient Relapse Disease progression Frequent injections "I don't feel like an MS patient, because sometimes I even forget like I have MS. This is what the drug has done for me." P.R., UK Phase 2 Trial Patient Patient Comments

Conclusions Alemtuzumab potentially offers a transformative approach to MS treatment Evolving and unique mechanism Potential for unprecedented efficacy Convenient dosing with possibility for patients to "forget" about their disease Manageable safety profile Monitorable adverse events Early detection allows intervention and recovery Benefit/risk favorable, especially in context of existing treatments Potential to ask core questions in MS treatment for the first time: Can we change the course of the disease in those naive to treatment? Can we prevent or reverse existing disability in those failing existing treatment? Can we induce a durable remission? Can we offer true freedom from clinically active disease and chronic treatment?

Q&A Moderated: Mark Enyedy, President, Transplant, Oncology and Multiple Sclerosis Panel: Michael Panzara, VP MS & Immune Diseases Professor Alastair Compston Dr. Alasdair Coles

October 2010 ECTRIMS Investor Presentation