Genzyme Reports Interim Results from Pivotal Study of Myozyme

“The results are extremely encouraging and confirm our plan to submit a BLA in the middle of this year,” said Richard A. Moscicki, senior vice president and chief medical officer for Genzyme Corp. “This analysis will allow us to seek U.S. approval for Myozyme as quickly as we had expected and to supplement our previously filed European marketing application with data from the pivotal study. We have proceeded with a great sense of urgency throughout the development of Myozyme, given the devastating nature of Pompe disease.”

The pivotal trial, known as AGLU01602, includes 18 patients with infantile-onset Pompe disease. These patients were enrolled in the trial and began receiving Myozyme by 6 months of age. Because of the rapidly progressive and fatal nature of infantile-onset Pompe disease, outcomes for these patients are being compared with a matched historical cohort rather than a placebo cohort.

The study’s primary endpoint is the proportion of patients treated with Myozyme who are alive and free of invasive ventilator support at 18 months of age, compared with the proportion of patients who were alive at 18 months of age in the historical cohort (2 percent). Results for the primary endpoint will be known this summer, when patients will have completed 52 weeks of treatment.

By 12 months of age, 89 percent of patients treated with Myozyme (16 of 18) were alive and free of invasive ventilator support compared with 17 percent of patients who were alive at 12 months of age in the historical cohort. This result meets a secondary efficacy endpoint and indicates the trial will very likely meet its primary endpoint.

The interim analysis also found the following:

• All patients treated with Myozyme showed a reversal in cardiomyopathy, a condition in which the heart muscle becomes enlarged and heart function is impaired. This reversal was measured by decreases in left ventricular mass index from baseline.
• 72 percent of patients treated with Myozyme demonstrated gains in motor development as measured by the Alberta Infant Motor Scale.
• All patients evaluated demonstrated gains in cognitive, language and personal/social skills from baseline.
• 83 percent of patients developed antibodies to Myozyme and 44 percent experienced infusion associated reactions.

Genzyme will submit data from study AGLU01602 to the European Medicines Agency, which is reviewing a marketing authorization application (MAA) for Myozyme filed in December 2004. The agency’s Committee for Human Medicinal Products is expected to make a decision on the application later this year. The MAA contains data from other studies, including AGLU01702, which enrolled patients with infantile-onset Pompe disease who were older than those in AGLU01602 and whose disease was more advanced.

Genzyme is pursuing approval for Myozyme’s use as a long-term enzyme replacement therapy for all patients with a confirmed diagnosis of Pompe disease, defined as acid alpha-glucosidase deficiency. There is currently no approved treatment for the disease. More than 100 patients are now receiving Myozyme in clinical studies, through Genzyme’s expanded access program, or through pre-approval mechanisms sponsored by governments in several European countries. The Myozyme program is Genzyme’s largest research and development initiative.

About Pompe disease

Pompe disease is an inherited, progressive muscle disease that affects fewer than 10,000 people worldwide. The disease is caused by a deficiency of an enzyme known as acid alpha-glucosidase. This deficiency leads to the excessive accumulation of glycogen in the body, particularly in the muscles. Pompe disease manifests as a broad spectrum of clinical symptoms with varying rates of disease progression. Infantile-onset patients present in the first months of life with an enlarged heart and skeletal and respiratory muscles weakness, and most die from cardiac or respiratory complications by one year of age. Late-onset patients may present with muscle or respiratory weakness anytime during childhood or adulthood, and disease progression is less rapid. Late-onset patients often require mechanical ventilation for breathing assistance and mobility aids such as canes, walkers or wheelchairs. Late-onset patients will experience a shortened lifespan due to progressive respiratory failure. Pompe disease belongs to a family of approximately 40 rare inherited diseases known as lysosomal storage disorders.

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 7,000 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, including statements about clinical trial results, regulatory plans and expected timelines for Myozyme, including the completion of the AGLU-01602 trial and the timing thereof, the submission of a BLA to the FDA and the timing thereof, and the expected timing of a decision from the Committee for Human Medicinal Products on Genzyme’s MAA. 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: the actual timing and content of submissions to and decisions made by the US and EU regulatory authorities regarding marketing authorization applications for Myozyme; the actual timing and final results of the Myozyme clinical trials; and the risks and uncertainties described in reports filed by Genzyme with the Securities and Exchange Commission. Please see the disclosure under the heading “Factors Affecting Future Operating Results” in the Management’s Discussion and Analysis of Financial Condition and Results of Operations section of Genzyme’s Annual Report on Form 10-K for the year ended December 31, 2004 for a more complete discussion of these and other risks. 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.

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