Cerezyme® (imiglucerase for injection) and Fabrazyme® (agalsidase beta) Supply Outlook - Understanding Genzyme’s Press Release of July 21, 2010 (7/21/2010)

Jul 21, 2010 - Today, Genzyme issued a press release as part of our standard reporting to the financial community. This included an update on our expectations for the supply of Cerezyme® and Fabrazyme in the coming months. The content in this press release is written primarily for investors, not the medical community, and may not answer the specific questions patients and their physicians have about how supply will affect treatment plans. As has been the case over the past several months, the answer to those questions will be somewhat different depending on where you live and your particular treatment plan. But we can provide some general information to help clarify what the language in the press release mean in terms of treatment availability.

CEREZYME®

First, we’d like to emphasize that our expectations for treatment availability are still consistent with our last update to the community on this website onJune 29, 2010. At that time, we informed the Gaucher disease community that the overall level of Cerezyme® available would be about the same in July as in the previous months and was expected to increase in the coming months. For most patients, we expect that increase to begin in September, but this could be earlier or later in some countries. The overall supply of Cerezyme® will be increasing through these months, but the complexities of distributing the drug around the globe, along with different prescribing practices and other administrative concerns, can affect exactly when patients’ doses or infusion frequency will be able to change.

In October through December 2010, we expect to supply significantly more Cerezyme® overall than in the prior 3 months. We believe that this means that, during the last 3 months of 2010, patients could expect to return to a dose similar to what they had before the supply shortage. However, we must remind everyone that because we are operating with very low inventory, even small disruptions at the Allston manufacturing facility or changes to our expected product timelines could reduce the amount of Cerezyme® that is available. We are continually working to improve our manufacturing processes and changes can sometimes introduce delays. Genzyme staff in your local area will be able to provide more detail about what to expect as we move through the coming months.

FABRAZYME

As with Cerezyme®, our expectations regarding Fabrazyme supply are still consistent with our last update on this website on June 29, 2010. At that time we informed the Fabry disease community that in the period from July through September, the overall level of Fabrazyme supply would be about the same as in previous months, however, due to variations in the timing of when drug will become available, some regions would likely see periods when Fabrazyme would be temporarily unavailable. This is still our expectation. Genzyme staff in each country are communicating with treatment centers, health authorities, and physicians to clarify the details of Fabrazyme availability over the coming months.

We do expect that supply will change in a meaningful way by the end of September, and in the October through December 2010 time period additional supply will be available to support increases in Fabrazyme dose or infusion frequency. Please keep in mind that the complexities of global distribution and local prescribing practices will affect exactly when patients’ doses or infusion frequency will change. The specific amount of Fabrazyme available for distribution beginning in October will be communicated by local Genzyme staff in September.

Although we have made improvements in Fabrazyme manufacturing, we have not reached our targeted levels of productivity and output. We continue to operate with very low inventory, and even small disruptions at the Allston manufacturing facility or changes to our timelines could reduce the amount of Fabrazyme that is available. We are continually working to improve our manufacturing processes and changes can sometimes introduce delays. We will continue to update the Fabry community as we work to stabilize supply, and Genzyme staff in your local area will be able to provide more detail about what to expect as we move through the coming months.

Thank you.

This posting contains forwarding-looking statements regarding Genzyme’s business plans and operations with respect to Cerezyme® and Fabrazyme including, without limitation, the amounts, timing and management of future supply and shipping allocations and patient dose and infusion schedules. These statements are subject to risks and uncertainties that may cause actual results to differ materially. These risks and uncertainties include, among others, that Genzyme is unable to transition Fabrazyme fill/finish operations for product sold in the U.S. to a third-party contract manufacturer within expected timeframes; that Genzyme’s demand forecasts and estimates are inaccurate; that production of Cerezyme® and/or Fabrazyme does not continue as planned due to any reason, including bacterial or viral contamination, equipment failures, cell growth at lower than expected levels, fill-finish inefficiencies, power outages or other disruptions of utility services, human error or regulatory issues; that Genzyme cannot maintain regulatory approvals for the new working cell bank for Fabrazyme; that compliance with the May 2010 FDA Consent Decree, including third-party oversight and/or the implementation of the remediation plan, results in additional or unexpected delays in product releases; 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 Amended Quarterly Report on Form 10-Q/A for the quarter ended March 31, 2010. Genzyme cautions investors not to place substantial reliance on the forward-looking statements contained in this posting. These statements speak only as of July 21, 2010 and Genzyme undertakes no obligation to update or revise them.