European Commission Approves Genzyme's Mozobil.

Product Provides Significant New Option for Certain Cancer Patients Requiring a Stem Cell Transplant

CAMBRIDGE, Mass. -- Genzyme Corporation (Nasdaq: GENZ) announced today that the European Commission has granted marketing authorization for Mozobil([R]) (plerixafor injection), providing a significant new option for patients with the blood cancers lymphoma and multiple myeloma who require an autologous stem cell transplant.

"Mozobil has the potential to transform the field of stem cell transplantation," said Mohamad Mohty, MD, PhD, Professor of Hematology and head of the Stem Cell Transplant Program at the University Hospital in Nantes, France. "This new treatment will allow more patients with yet incurable malignancies to confidently move on to a potentially life-saving autologous stem cell transplant."

In Europe, Mozobil is indicated in combination with granulocyte-colony stimulating factor (G-CSF) to enhance mobilization of stem cells to the bloodstream for collection and subsequent autologous transplantation in patients with lymphoma and multiple myeloma whose cells mobilize poorly. This indication allows physicians to use Mozobil in the broad group of patients who are at risk of poor mobilization, as well as those who have previously failed conventional treatment. The product has been granted orphan drug status in the European Union and United States.

More than 1,000 patients in Europe have already received Mozobil through compassionate use programs that began about one year ago. These patients had failed to mobilize enough cells for transplantation using the current standards of care, or were predicted to fail mobilization based on clinical laboratory indicators.

"There is strong interest among European physicians for Mozobil," said Genzyme Vice President and General Manager, Mozobil, Paula Soteropoulos. "With today's approval, we will move quickly to make this important product broadly available to the transplant community."

In addition to its clinical benefits for patients with lymphoma and multiple myeloma, Mozobil may offer economic benefits for transplant centers. The product has the potential to decrease the number of apheresis days and therefore provide increased predictability and more efficient use of transplant center resources. Mozobil may also reduce the number of patients who require a second mobilization procedure due to a failure to mobilize sufficient numbers of cells with other methods.

Mozobil, in combination with G-CSF, is designed to release hematopoietic stem cells from the bone marrow into the bloodstream where they can be collected, making it more likely for patients with certain types of cancers to proceed to autologous transplant. Currently, before a transplant can take place, patients may receive a prescribed dose of chemotherapy and/or other drugs called growth factors to help mobilize their hematopoietic stem cells into the bloodstream. Once the cells are released into the bloodstream, they are collected in preparation for a transplant.

In order for the transplant to take place, a minimum number of approximately two million stem cells per kilogram of body weight must be collected, and physicians may seek two-and-a-half times more stem cells than the minimum transplantable number to allow for better outcomes. For many patients, the stem cell collection process can take three or four hours over multiple days to complete. Even then, some patients are not able to mobilize enough cells, and a transplant is not possible.

Mozobil was evaluated in two randomized, double-blind, placebo controlled, phase 3 studies in patients with non-Hodgkin's lymphoma and multiple myeloma. Patients were given Mozobil plus G-CSF or placebo plus G-CSF. The studies found that Mozobil in combination with G-CSF increased the number of patients achieving both the minimum and target stem cell levels in fewer apheresis sessions; allowed more patients to proceed to transplant; and increased the predictability of apheresis stem cell yield and timing.

Year-long follow-up data also showed that the graft durability rates were comparable in the Mozobil plus G-CSF and placebo plus G-CSF trial arms.

Genzyme has filed applications for the approval of Mozobil in Argentina, Australia, Brazil, Israel, and Singapore, and additional applications are planned globally. In May, Mozobil was launched in Mexico. Approximately 55,000 hematopoietic stem cell transplants are performed each year globally for multiple myeloma, Hodgkin's and non-Hodgkin's lymphoma, and other conditions. Genzyme expects that over time and with further clinical development, Mozobil will be used in the majority of these procedures. Peak sales of the product in the transplant setting are projected to reach $400 million annually.

About Mozobil

Mozobil was approved in the United States in December 2008 where it is indicated for use in combination with granulocyte-colony stimulating factor (G-CSF) to mobilize hematopoietic stem cells to the bloodstream for collection and subsequent autologous transplantation in patients with non-Hodgkin's lymphoma and multiple myeloma. Prescribing physicians and patients should be aware of the potential for tumor cell mobilization in leukemia patients, increased circulating leukocytes and decreased platelet counts, splenic enlargement, and fetal harm when administered to pregnant women. The most common adverse reactions ( 10%) reported in patients who received plerixafor in conjunction with G-CSF that were more frequent than in patients who received placebo were diarrhea, nausea, fatigue, injection site reactions, headache, arthralgia, dizziness and vomiting. For full prescribing information, please visit www.genzyme.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 11,000 employees in locations spanning the globe and 2008 revenues of $4.6 billion.

With many established products and services helping patients in nearly 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, and diagnostic testing. 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 business plans and strategies including, without limitation, statements about: the significance of the new treatment option presented by Mozobil for patients with lymphoma and multiple myeloma who require an autologous stem cell transplant; the potential to transform the field of stem cell transplantation; the potential for allowing more patients to proceed to a potentially life-saving autologous stem cell transplant; the potential offered by the labeled indication in Europe for broad use by physicians; the level of interest among European physicians for Mozobil; Genzyme's ability to move quickly to make the product available; the potential for economic benefits for transplant centers due to potential decreases in apheresis days, increased predictability and more efficient use of transplant center resources; the potential for Mozobil to reduce the number of patients who require a second mobilization effort; Mozobil's role in the release of hematopoietic stem cells; physician mobilization strategies with respect to collection of a minimum transplantable number of cells to allow for potentially better outcomes; Genzyme's regulatory filing and further clinical development plans; the number of stem cell transplants globally and Genzyme's expectations as to Mozobil's potential use in such procedures; and Genzyme's projection for annual Mozobil revenues. 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: the actual efficacy and safety of Mozobil; the adoption of Mozobil by physicians for use in stem cell transplants; the extent to which national health authorities are willing to reimburse for use of Mozobil; the ability of transplant centers to realize economic benefits associated with the use of Mozobil; the ability of Genzyme to execute its product launch strategy; 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 period ended March 31, 2009. Genzyme cautions investors not to place undue 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 the statements.

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