Genzyme Expands MyozymeTM

Genzyme Expands MyozymeTM

Date: September 10, 2003

Genzyme Corp. (Nasdaq: GENZ) today announced the launch of several initiatives designed to support the rapid development and approval of MyozymeTM recombinant human acid alpha-Glucosidase and provide greater access to the enzyme for patients in need during the development process.

These initiatives-which do not alter the planned timing of marketing applications-include new clinical studies, special access programs, and a disease registry. Genzyme is developing Myozyme for the treatment of Pompe disease-a rare, progressive and often fatal muscle disease resulting from an underlying lysosomal storage disorder. 

The Myozyme program is the company's largest and most advanced research and development effort. Genzyme is currently conducting two clinical trials of Myozyme involving patients younger than three years of age with the infantile-onset form of Pompe disease. Because symptoms are most severe and progress most quickly in the infantile onset-form, and because children often die before age one, Genzyme chose to study Myozyme first in these patients. A limited product supply had precluded simultaneous clinical studies involving older patients, who require significantly more enzyme.

The company is making steady progress in increasing its supply of Myozyme and scaling up its manufacturing capacity, and it now plans to initiate clinical studies involving older children and adults and to create special access programs that will increase the availability of Myozyme to patients in need who are unable to participate in clinical trials. New Clinical Studies Genzyme anticipates submitting U.S. and European marketing applications for Myozyme in the second half of 2004 based on results from its two ongoing infantile-onset trials and from previous studies of enzyme replacement therapy for Pompe disease.

Marketing applications in other territories would follow the U.S. and European submissions. To collect additional clinical data to support approval for Myozyme's use in all patients, Genzyme plans to conduct two additional studies.

First, it will conduct a short-term observational study that will enroll approximately 60 patients with mild to intermediate late-onset Pompe disease. Data from this study, which will begin this fall, will be used to help design a placebo-controlled clinical trial. The placebo-controlled, dose-ranging trial will include a subset of patients from the observational study who meet the trial's inclusion criteria. It is expected to begin in 2004 and to last one year. Special Access Programs Given the debilitating and life-threatening nature of Pompe disease, Genzyme intends to provide broader access to Myozyme to severely ill patients who are not participating in clinical trials.

The company will work with regulatory authorities, government officials, clinicians and patient associations to pursue the appropriate mechanisms for expanding access to Myozyme. In the past, Genzyme has successfully utilized these mechanisms to make investigational products available to patients in need prior to marketing authorization. The company is creating two special access programs, one focused on infantile-onset patients and the other on late-onset patients. The former will open first for severely affected infants who are ineligible to participate in Genzyme's ongoing clinical studies. The latter will include a limited number of patients who likely would be ineligible for the placebo-controlled late-onset clinical trial because of the severity of their disease. Initially, the late-onset program will be conducted in cooperation with health authorities in a number of countries with regulatory structures that facilitate pre-approval access to investigational products for patients in need.

Enrollment in both programs is expected to begin later this year and will be limited, at first, to a relatively small number of patients because of product supply constraints. Genzyme will increase enrollment in the programs over time, as product supply grows.

Disease Registry

Genzyme plans to establish a registry designed to improve knowledge about Pompe disease by documenting the natural course of disease, clinical outcomes, and disease management. All patients with Pompe disease are eligible to participate in the registry through their treating physicians. Enrollment is expected to begin within the next several months.

Genzyme has significant experience in designing and managing registries for other lysosomal storage disorders, namely Gaucher disease, MPS I, and Fabry disease. "We are working diligently to bring Myozyme to Pompe patients as quickly as possible," said Henri A. Termeer, chairman and chief executive officer of Genzyme Corp. "By assuring that studies are underway and initiatives in place to capture data over the long term, we hope to provide regulatory authorities with the confidence to approve Myozyme in the near term.

Our approach is based on our recent experience in working with advisory panels and regulatory agencies to facilitate the approval of treatments for two other very rare, complex and life-threatening diseases. Given the urgent medical needs of Pompe patients and the extraordinary development challenges posed by this disease, we welcome and encourage all stakeholders to share the responsibility with us to think and act in innovative ways, so that a treatment is made available to all Pompe patients soon. Genzyme recognizes the devastating toll Pompe disease takes on patients and their families, and we are determined to overcome any obstacles in bringing a treatment to these patients."

Ria Broekgaarden, commenting on behalf of the International Pompe Association board of directors, said: "For people with Pompe disease, broader access to Myozyme because of new clinical trials and the start of the expanded access programs is a very important step. Next steps are needed urgently, because everyone still will not have access to therapy and some patients will have to wait while their disease is progressing.

The IPA supports Genzyme's endeavors to improve the quality of life for adult Pompe patients by starting clinical trials in adults. IPA will continue to advocate on behalf of all Pompe patients to make Myozyme available in sufficient quantities for all patients as soon as possible. We should all be convinced that Genzyme will do its utmost to meet the expectations of patients worldwide." Robert Ross, president and chairman of the Muscular Dystrophy Association, said: "Pompe disease is among the over 40 neuromuscular disorders covered by the Muscular Dystrophy Association. Pompe is a devastating muscle disease that has brought suffering to many patients and their families. Genzyme's commitment and progress brings hope to these patients, and we at the MDA look forward to further developing our partnership with Genzyme to support clinical research and expanded access initiatives."

About Pompe Disease

 Pompe disease is a rare and often fatal muscle disease caused by an inherited deficiency of the enzyme acid alpha-glucosidase, which is responsible for breaking down glycogen within cells. Pompe disease ranges from a rapidly fatal infantile-onset form with severe cardiac involvement to a more slowly progressive late-onset form primarily affecting skeletal muscle. There is currently no therapeutic treatment available for the disease, which affects an estimated 5,000-10,000 people worldwide.

Genzyme Corporation is a global biotechnology company dedicated to making a major positive impact on the lives of people with serious diseases. The company's broad product portfolio is focused on rare genetic disorders, renal disease, and osteoarthritis, and also includes an industry-leading array of diagnostic products and services. Genzyme's commitment to innovation continues today with research into novel approaches to cancer, heart disease, and other areas of unmet medical need. Genzyme's 5,300 employees worldwide serve patients in more than 80 countries.

This press release contains forward-looking statements, including statements about: expectations concerning the development and potential approval and availability of Myozyme; expectations concerning the sufficiency of supplies of Myozyme; plans concerning additional studies and a disease registry related to Pompe disease, including the anticipated timing and design of studies; plans concerning an expanded access program, including the anticipated timing of enrollment in the program; and estimates concerning the Pompe patient population.

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 receipt of IRB approvals for clinical trials and the timing thereof; participation levels and enrollment rates for the planned observational study, clinical trials and disease registry; the actual efficacy and safety of Myozyme in humans and the actual timing and final design of studies and clinical trials; the results of pre-clinical and clinical studies; the actual timing and content of discussions with, submissions to and decisions made by regulatory authorities concerning Myozyme and related facilities, including the nature and extent of data required for marketing applications and the anticipated expanded access program; continued progress in scaling-up facilities for Myozyme; the results and timing of qualifying runs at facilities; the ability to manufacture sufficient quantities of product for development activities (including without limitation extension studies and expanded access arrangements) and to do so in a timely and cost-efficient manner; the accuracy of Genzyme's information concerning the Pompe patient population; the availability and extent of coverage for Myozyme from third party payors; and 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 Exhibit 99.2 to Genzyme's 2001 Annual Report on Form 10-K, as amended. We caution 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 we undertake no obligation to update or revise the statements. Genzyme7 is a registered trademark and MyozymeTM is a trademark of Genzyme Corporation. All rights reserved.

Genzyme's press releases and other company information are available at www.genzyme.com and by calling Genzyme's investor information line at 1-800-905-4369 within the United States or 1-703-797-1866 outside the United States.

 For More Information Physicians or patients who would like more information about clinical studies or Myozyme special access programs may contact Genzyme's Medical Information department. The email address in the United States is medinfo@genzyme.com and the telephone number is 800-745-4447. In Europe, the email address is eumedinfo@genzyme.com and the telephone number is 31-35-699-1499, or contact your local Genzyme office.

For more information about Pompe disease, please visit www.pompe.com. For more information about Genzyme's Pompe disease research and development program, please visit www.genzyme.com/pompe/pompe_home.asp.