Renagel in New Dialysis Study Published in Kidney International

Data Show That Patients Treated with Renagel Achieve Mortality Benefit

January 8, 2007 - Genzyme Corporation (Nasdaq: GENZ) announced today that findings published in the online version of Kidney International demonstrate that patients using Renagel experienced a significantly lower rate of death compared with patients using calcium-based phosphate binders in a newly completed study.

The results were drawn from the Renagel in New Dialysis study (RIND), a randomized open-label trial involving 127 patients new to hemodialysis at five dialysis centers in the United States. All-cause mortality was a pre-specified secondary endpoint. Results of the primary endpoint - a comparison of the degree of coronary artery calcification after 18 months of treatment - were published last year and also showed a statistically significant result in favor of the Renagel-treated population.

According to the study design, patients new to hemodialysis were randomized to receive either Renagel or a calcium-based phosphate binder, and were followed for an average of 44 months of treatment. Over the treatment period, 34 deaths occurred among study participants, including 23 patients who were using calcium-based binders and 11 who were using Renagel. The difference between the two groups was statistically significant (p=0.05). After adjustments were made for a range of factors, including age, race, gender and several baseline medical characteristics, the difference between the two groups was even greater (p=0.016).

“These results are significant because they show for the first time that higher levels of coronary artery calcification are associated with a higher incidence of death in patients on dialysis,” said principal investigator Geoffrey Block, M.D., of Denver Nephrologists, PC, Denver, Colorado. “Given the high mortality rate seen in patients on dialysis, control of coronary artery calcification should be an important consideration for health professionals when determining the type of therapy that is appropriate for their patients.”

Today’s findings build on previously published data by establishing a link between choice of phosphate binders, calcification levels, and mortality. Earlier results from the RIND study showed that while each type of phosphate binder helped patients achieve the target levels for phosphorus and calcium-phosphorus product outlined in the 2003 National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines, patients using calcium-based phosphate binders experienced more rapid and more severe progression of coronary artery calcification than those using Renagel.

“This study provides important insights for patients and caregivers by highlighting the benefits of initiating treatment with Renagel from the time that a patient begins on dialysis,” said Richard Moscicki, chief medical officer, Genzyme.

The Renagel in New Dialysis study was funded by Genzyme.

About Renagel

Renagel controls serum phosphorus in patients with chronic kidney disease on hemodialysis. Controlling serum phosphorus is an important element in the care of hemodialysis patients. Elevated serum phosphorus levels are common in dialysis patients and associated with increased risk of cardiovascular mortality. Renagel provides the added benefit of significant LDL cholesterol reduction (32 percent).

The National Kidney Foundation’s 2003 K/DOQI guidelines for Bone Metabolism and Disease in Chronic Kidney Disease recommend sevelamer hydrochloride as a first-line treatment option to control phosphorus. Renagel is the only phosphate binder available that does not contain either calcium or a metal. It has an established safety profile, is not systemically absorbed and provides phosphorus control without the concerns of calcium or metal accumulation. Renagel is used by more than 350,000 people worldwide.

Product Information

Renagel is indicated for the control of serum phosphorus in patients with chronic kidney disease (CKD) on hemodialysis. Renagel is contraindicated in patients with hypophosphatemia or bowel obstruction. In a 52-week study, the most common side effects included vomiting, nausea, diarrhea, and dyspepsia. Drug-drug interactions may occur with some medications and should be taken into consideration when instructing patients how to take Renagel.

For more information about Renagel, including complete prescribing information, please visit www.renagel.com.

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 9,000 employees in locations spanning the globe and 2005 revenues of $2.7 billion. Genzyme has been selected by FORTUNE as one of the “100 Best Companies to Work for” in the United States.

With many established products and services helping patients in more than 80 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 diseases, and diagnostic testing. Genzyme’s commitment to innovation continues today with a substantial development program focused on these fields, as well as heart disease and other areas of unmet medical need.

This press release contains forward-looking statements including, without limitation, statements about the RIND study’s effect on physicians’ treatment of dialysis patients. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected in these forward-looking statements. These risks and uncertainties include, among others: additional analysis of the RIND data; the results of other studies and whether such results are consistent with the RIND data; the availability and extent of third-party reimbursement for Renagel®; 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 “Factors Affecting Future Operating Results” in the Management’s Discussion and Analysis of Financial Condition and Results of Operations section in Genzyme’s Quarterly Report on Form 10-Q for the period ended September 30, 2006. 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® and Renagel® are registered trademarks of Genzyme Corporation.

Contact Information

Dan Quinn

Media Contact

Genzyme Corporation

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