Genzyme Acquires Avigen’s Gene Therapy Technology

December 21, 2005, Genzyme Corp. (Nasdaq: GENZ) today announced that it has acquired extensive gene therapy assets from Avigen, Inc., including rights to a broad patent estate focused on adeno-associated virus technology, a Phase 1/2 clinical development program in Parkinson’s disease, and a clinical collaboration in hemophilia.

In exchange for these assets, Genzyme has made an up-front cash payment of $12 million to Avigen, and will make potential milestone and royalty payments based on the development, approval and sale of products developed under the intellectual property portfolio.

The acquired assets will support and diversify Genzyme’s industry-leading gene therapy research program, which already includes work in cardiovascular disease, lysosomal storage disorders, and other conditions. Together with last month’s acquisition of viral manufacturing facilities from Cell Genesys, Genzyme has significantly strengthened its ability to develop gene therapy products that utilize either adenovirus or adeno-associated virus vectors.

“This agreement provides Genzyme with a strong patent estate for our existing gene therapy platform, and reflects our commitment to achieve the medical advances that we believe are possible with this technology,” said Rich Gregory, Genzyme’s head of research. “We look forward to advancing Avigen’s ongoing work in Parkinson’s disease and hemophilia, areas where we believe gene therapy could play a meaningful role in treatment.”

The most advanced program in Genzyme’s gene therapy portfolio is a Phase 2 clinical trial examining the safety and effectiveness of locally delivered Ad2/HIF-1_, an engineered form of the HIF-1_ gene. This experimental therapy is designed to promote the growth of new blood vessels and improve circulation in the limbs of patients with peripheral arterial disease. Genzyme’s gene therapy portfolio also includes pre-clinical work related to lysosomal storage disorders and, in partnership with Excigen, Inc., atrial fibrillation. Genzyme is also conducting pre-clinical gene therapy research through a joint effort with Applied Genetic Technologies.

The Phase 1/2 clinical trial in Parkinson’s disease is designed to evaluate the safety of increasing doses of AV201 in individuals with mid- to late-stages of the disease. AV201 is designed to restore the therapeutic effectiveness of levodopa, the primary treatment for Parkinson’s disease, by enhancing the brain’s ability to convert it into dopamine. The trial, which will now be funded by Genzyme, was initiated in December 2004, at the University of California San Francisco (UCSF) and Lawrence Berkeley National Laboratory (LBNL). Three patients have been treated in this planned 15-patient trial.

In addition, Genzyme will continue Avigen’s clinical collaboration in hemophilia gene therapy with Dr. Katharine High of the University of Pennsylvania School of Medicine.

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. Founded in 1981, Genzyme has grown from a small start-up to a diversified enterprise with annual revenues exceeding $2 billion and more than 8,000 employees in locations spanning the globe. 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 that subject to risks and uncertainties that could cause actual results to differ materially from those projected. These risks and uncertainties include 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 of the Genzyme Annual Report on Form 10-Q for the quarter ending September 30, 2005. 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 the statements.

Genzyme® is a registered trademark of Genzyme Corporation. All rights reserved.

Contact Information

Erin Emlock

Public Relations Specialist

Genzyme Corporation

Contact via E-mail