Update on Cerezyme and Fabrazyme supply from Genzyme Corporation

Genzyme Corporation (NASDAQ: GENZ) today provided an update on its progress to restore supplies of Cerezyme® (imiglucerase for injection) and Fabrazyme® (agalsidase beta) for patients worldwide and revised its 2009 revenue guidance for these products. The company is now approximately half-way through the anticipated shortage period for Cerezyme and Fabrazyme, the restart of the Allston Landing manufacturing facility is complete, and if production continues to proceed as planned, Genzyme expects that it can begin meeting anticipated patient demand for both products during the first quarter of 2010.

All six bioreactors at the Allston plant are fully operational and have reached the point in their production cycles when their anticipated output and the timing of product release can be predicted with more certainty. Cerezyme production is proceeding on track, with four bioreactors producing bulk material at levels in the higher range of Genzyme’s historical experience for the product. The company anticipates that newly produced Cerezyme will be available for shipment beginning in November and December as planned.

The first shipments of newly produced Fabrazyme are now expected to occur in mid-December, and the volume of finished product initially available for release will be lower than anticipated. There are several factors that have contributed to the production delay and lower product volume. Fabrazyme bioreactors were re-started later than planned in order to perform preventative maintenance and sanitization procedures related to the decontamination of the facility. In addition, output from the two Fabrazyme bioreactors is expected to be in the lower range of Genzyme’s historical experience for the product. Also, to ensure global access to Fabrazyme as quickly as possible, Genzyme has been processing bulk material in smaller batches, which leads to faster availability of final product but also leads to losses in process efficiency and lower overall volume. As a result, additional product conservation measures are now needed to help ensure that the limited remaining Fabrazyme inventory can be made available to as many patients as possible until new material is available.

In June, Genzyme determined that its Fabrazyme inventory was sufficient to support approximately 80 percent of global patient demand through October. Dose conservation guidelines were implemented by the Fabry physician and patient community to help ensure that the reduced product supply was distributed according to clinical guidelines. To date, these conservation measures have been successful. Today, Genzyme has enough Fabrazyme inventory to cover 80 percent of forecasted demand through October, the last remaining month of the original dose conservation plan. However, to help ensure the global availability of the remaining Fabrazyme inventory until new product is available, Genzyme will begin shipping enough product to meet approximately 30 percent of forecasted global patient demand starting October 1^st, until the end of 2009. Revised clinical guidelines are expected to be formulated by stakeholder working groups and regulatory authorities to establish the basis for use of this material. Individual treatment decisions will need to be made by patients and physicians, as locally appropriate, with the aid of these guidelines.

“We have reached a point in this process where we can anticipate with greater confidence the timing and amount of the first finished product to be shipped from the Allston plant,” said Henri A. Termeer, Genzyme’s chairman and chief executive officer. “We will continue to work with all stakeholders to prepare for the release of this material so that it can reach patients as quickly as possible. I want to express my deep appreciation to the Gaucher and Fabry communities for their support of the existing product conservation guidelines and for their anticipated collaboration in helping to manage the remaining limited product supply through the end of this year.”