07/17/2008

Genzyme Corporation and PTC Therapeutics Announce Collaboration on Small Molecules for Genetic Diseases

Potential New Treatment Paradigm, PTC124

Cambridge, MA and South Plainfield, NJ - July 17, 2008 - Genzyme Corporation (Nasdaq: GENZ) and PTC Therapeutics, Inc. (PTC) today announced an exclusive global collaboration to develop and commercialize PTC124, PTC's novel oral therapy in late-stage development for the treatment of genetic disorders due to nonsense mutations. Under the terms of the agreement, PTC will commercialize PTC124 in the United States and Canada, and Genzyme will commercialize the treatment in all other countries. Genzyme will make an up-front payment of $100 million to PTC, plus potential milestone and royalty payments. PTC will be financially responsible for one ongoing and three additional clinical trials of PTC124, which is potentially applicable to hundreds of genetic diseases.

PTC124 is currently being evaluated in a phase 2b trial for Duchenne muscular dystrophy (DMD), and a phase 2b trial in cystic fibrosis (CF) is expected to begin by the end of this year. In its collaboration with PTC, Genzyme will draw on its expertise in genetic disorders and its strong regulatory, manufacturing and marketing infrastructure outside of the United States. Genzyme has extensive experience with cystic fibrosis, having conducted more than six clinical trials among CF patients. In the field of DMD, Genzyme's experience with Myozyme® (alglucosidase alfa), for the treatment of the genetic disorder Pompe disease, will be directly applicable as patients with both diseases are treated by the same specialist physicians.

"Over the past two decades, Genzyme has successfully developed four therapies for patients with severe genetic diseases. PTC124 is a powerful new approach that holds great potential to help CF and DMD patients, and many others with a variety of devastating diseases," stated Henri A. Termeer, Genzyme's chairman and chief executive officer. "This collaboration is an excellent strategic fit for Genzyme and will be managed within the company's stated financial guidance."

"One of PTC's earliest scientific insights was that targeting nonsense mutations represented a novel approach to treating a large number of genetic disorders. The translation of that insight through the discovery and rapid development of PTC124 has been very gratifying," commented Stuart W. Peltz, Ph.D., PTC's president and chief executive officer. "This collaboration supports PTC's business strategy of establishing a fully integrated biopharmaceutical company by retaining commercial rights in the United States and Canada while engaging an experienced and capable partner to swiftly address additional markets."

PTC initiated the clinical development of PTC124 in 2004. Based on phase 2a clinical proof of concept in both DMD and CF, further development in each of these indications is being pursued in international, multicenter trials. A phase 2b trial of PTC124 in DMD is currently enrolling, and is expected to include 165 patients. A phase 2b trial of PTC124 in CF is planned to begin by the end of this year. With demonstration of clinical benefit, these two trials are expected to serve as the basis for registration of PTC124 in these indications. Further development of PTC124 will include clinical trials in multiple additional genetic disorders.

In the United States, there are an estimated 10,000 DMD patients, approximately 13 percent of which have nonsense mutations. Of the more than 30,000 U.S. patients with CF, about 10 percent have nonsense mutations. There is a significant unmet medical need for new treatments for these diseases. In addition to DMD and CF, the companies plan to explore PTC124's potential to make a difference for patients with other types of severe and debilitating genetic diseases.

"We are impressed by the quality of the preliminary PTC124 data, which suggest broad applicability to a large number of genetic disorders," said Geoff McDonough, M.D., Genzyme's senior vice president and general manager of LSD Therapeutics. "PTC124 is an excellent example of the promise that personalized medicine holds to address significant unmet medical needs, and we are excited about its potential to make a major positive difference in the lives of patients and their families."

"We are delighted to enter into this collaboration with Genzyme, a world-recognized pioneer and leader in the development of treatments for genetic disorders," commented Cláudia Hirawat, PTC's senior vice president of corporate development. "Because of its novel mechanism of action, PTC124 has the potential to address the underlying cause of disease in a subset of patients affected by more than 2,400 rare genetic disorders. PTC and Genzyme are well suited as partners to realize the full potential inherent in the broad applicability of PTC124."

DEAL TERMS Under the terms of the agreement, Genzyme will make a $100 million up-front payment to PTC Therapeutics. PTC will conduct and be financially responsible for the phase 2b trial of PTC124 in DMD, the phase 2b trial in CF, and two proof-of-concept studies in other indications to be determined. Once these four studies are completed, the companies will share research and development costs equally. Genzyme and PTC will each bear the sales, marketing and other costs associated with commercialization of PTC124 in their respective territories.

PTC is eligible to receive up to $337 million in total milestone payments, as follows: up to $165 million in development and approval milestones, the majority of which are to be paid upon approvals in Genzyme territories; and up to $172 million in sales milestones, contingent upon the achievement of specific sales levels. The sales milestone payments begin when annual net revenues reach $300 million, and increase in increments through revenues of $2.4 billion. PTC is also eligible to receive tiered double-digit royalties from sales in Genzyme territories.

ABOUT PTC124 PTC124 is an orally delivered, investigational new small molecule drug for the treatment of genetic disorders due to nonsense mutations. Nonsense mutations are single-point alterations in the genetic code that prematurely stop the translation process, preventing production of a full-length, functional protein. In phase 2a clinical trials in nonsense-mutation-mediated cystic fibrosis and in nonsense-mutation-mediated Duchenne muscular dystrophy, PTC124 has demonstrated the ability to produce functional protein across a variety of nonsense mutation types.

Across all clinical studies to date, PTC124 has been generally well tolerated and has achieved target plasma concentrations associated with activity in preclinical models. PTC124 is currently in phase 2b development with the goal of demonstrating that increasing functional protein levels in patients with nonsense-mediated genetic disorders will provide clinical benefits.

PTC124 has been granted orphan drug status for the treatment of DMD and CF due to nonsense mutations by the FDA and the European Commission. The FDA has also granted PTC124 Subpart E designation for expedited development, evaluation and marketing. The development of PTC124 is supported by grants from the Cystic Fibrosis Foundation, the Muscular Dystrophy Association, Parent Project Muscular Dystrophy, FDA's Office of Orphan Products Development and by General Clinical Research Center grants from the National Center for Research Resources.

ABOUT DUCHENNE MUSCULAR DYSTROPHY Duchenne muscular dystrophy is characterized by rapid progession of muscle degeneration, eventually leading to loss in ambulation, paralysis, and death. DMD eventually affects all voluntary muscles, as well as the heart and breathing muscles, and patients rarely survive beyond their early 30s. Each year, approximately 20,000 children worldwide are born with DMD (one of every 3,500 male children), making it the most prevalent of muscular dystrophies. There is a commercially available test to determine whether a patient's DMD is caused by a nonsense mutation. More information on DMD is available through the Muscular Dystrophy Association (www.mdausa.org) and the Parent Project Muscular Dystrophy (www.parentprojectmd.org).

ABOUT CYSTIC FIBROSIS Cystic fibrosis affects the mucus glands of the lungs, liver, pancreas, and intestines, causing progressive disability due to multisystem failure. It is among the most common life-threatening genetic disorders, affecting nearly 70,000 people worldwide. There is a commercially available test to determine whether a patient's CF is caused by a nonsense mutation. More information regarding CF is available through the Cystic Fibrosis Foundation (www.cff.org).

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. Since 1981, the company has grown from a small start-up to a diversified enterprise with more than 10,000 employees in locations spanning the globe and 2007 revenues of $3.8 billion. In 2007, Genzyme was chosen to receive the National Medal of Technology, the highest honor awarded by the President of the United States for technological innovation. With many established products and services helping patients in nearly 90 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 diagnostic testing. Genzyme's commitment to innovation continues today with a substantial development program focused on these fields, as well as immune disease, infectious disease, and other areas of unmet medical need.

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 1-678-999-4572 outside the United States.

ABOUT PTC THERAPEUTICS INC. PTC is a biopharmaceutical company focused on the discovery, development and commercialization of orally administered, proprietary, small-molecule drugs that target post-transcriptional control processes. Post-transcriptional control processes regulate the rate and timing of protein production and are of central importance to proper cellular function. PTC's internally-discovered pipeline addresses multiple therapeutic areas, including genetic disorders, oncology and infectious diseases. PTC has extensive knowledge of post-transcriptional control processes and has developed proprietary technologies that it applies in its drug discovery activities, including the Gene Expression Modulation by Small-molecules (GEMS) technology, which has been the basis for collaborations with leading biopharmaceutical companies such as Pfizer, Celgene, CV Therapeutics and Schering-Plough. For more information, visit the company's website www.ptcbio.com.

PTC Therapeutics® and PTC124TM are trademarks of PTC Therapeutics, Inc. All rights reserved.

GENZYME SAFE HARBOR STATEMENT This press release contains forward-looking statements, including without limitation, statements regarding the commercialization of PTC124; the benefits and potential broad applicability of PTC124 to treat multiple diseases; the development plan for PTC124 and expectations regarding phase 2b trials of PTC124 in Duchenne muscular dystrophy and cystic fibrosis; and the management of the collaboration within Genzyme's stated financial guidance. 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 ability of Genzyme and PTC to successfully complete the necessary clinical research on PTC124, including the risk that PTC124 will not meet its expected clinical endpoints; the parties' ability to obtain and maintain the necessary regulatory approvals for PTC124 in the expected indications and the timing of those approvals; the actual safety and efficacy of PTC124; the parties' ability to manufacture and commercialize PTC124; the possibility that other companies will seek to enter the same market or markets; the availability and extent of reimbursement for PTC124; 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 the information under the heading "Risk Factors" in the Management's Discussion and Analysis of Financial Condition and Results of Operations section of the Genzyme Quarterly Report on Form 10-Q for the quarter ended March 31, 2008. 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.

Contacts:
Genzyme Investors, Media
Patrick Flanigan, Erin Emlock
617-768-6563, 617-768-6923

Contacts:
PTC Investors and Media
Jane Baj, Andrea Johnston
(908) 912-9167, (910) 616-5858

Contacts:
Patients, Patients' Families, Investigators and Patient Organizations
Diane Goetz
(908) 912-9256