Genzyme and Dyax Announce Joint Venture for DX-88 in Hereditary Angioedema.

Business Editors/Health/Medical Writers

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CAMBRIDGE, Mass.--(BUSINESS WIRE)--June 24, 2003

Genzyme General (Nasdaq:GENZ), a division of Genzyme Corp., and Dyax Corp. (Nasdaq: DYAX) announced today Genzyme's decision to exercise its option to acquire a 50 percent interest in the DX-88 program for the potential treatment of hereditary angioedema (HAE) and potentially other chronic inflammatory indications. DX-88 is in phase II clinical trials for HAE, a rare disease characterized by acute episodic attacks of subcutaneous, abdominal and/or laryngeal swelling.

The decision by Genzyme follows its review of clinical data from the first completed phase II clinical trial of DX-88 for HAE, an open-label 9-patient study conducted by Dyax in Europe. Initial results of the study demonstrated that all patients met the primary endpoint, as announced by Dyax in March.

In addition to the European phase II study, a 48-patient, double-blind placebo-controlled dose escalating phase II study (Evaluation of DX-88's Effect on Mitigating Angioedema; EDEMA1) of DX-88 is being conducted under a U.S. IND. The first of four dose cohorts in EDEMA1 is completed and the second cohort is underway. DX-88 has received orphan drug designation for the treatment of angioedema by both U.S. and European regulatory authorities.

Under the terms of the joint venture, both companies will share development costs of DX-88 for HAE going forward. In addition, Dyax will receive milestone payments from Genzyme upon dosing the first HAE patient in a pivotal clinical trial of DX-88 and upon regulatory approval for the first indication. In addition, Dyax will receive milestone payments from Genzyme if DX-88 is approved in additional chronic inflammatory indications. Contingent upon regulatory approval of DX-88 for HAE, Genzyme will market the product worldwide, and Genzyme and Dyax will equally share profits from sales of DX-88 for HAE and/or other chronic inflammatory diseases. In March 2003, Dyax exercised an option to acquire from Genzyme all rights to DX-88 in surgical indications.

"Genzyme clearly has tremendous experience and strength in orphan drug development and marketing of products for unmet medical needs. They have demonstrated that significant and sustainable markets can be built for products that treat little known conditions. We could not have a more suitable partner. We have already established a successful working relationship with Genzyme and look forward to working together on advancing DX-88 through pivotal clinical trials and potential U.S. regulatory approval," commented Henry E. Blair, Chairman and CEO of Dyax Corp.

"We are enthusiastic about joining with Dyax to pursue the further development of DX-88, which holds promise for patients who suffer from hereditary angioedema," said Henri A. Termeer, chairman and chief executive officer of Genzyme Corp. "This opportunity is consistent with our focus on developing innovative therapies for patients with rare genetic disorders for which an unmet medical need exists. We are encouraged by the results of early clinical studies of DX-88 and by our conversations with physicians and patients. We look forward to working with Dyax to bring this product forward."

"The human toll of HAE in terms of disability and even death is tragic. Sadly, the anabolic steroids being used in the U.S. for attack prevention are often ineffective and can produce untoward side effects such as liver toxicity and, in female patients, virilization. The HAE community is thrilled that Genzyme is joining with Dyax in testing and developing DX-88 as a treatment for our dreadful disease," noted Anthony Castaldo, Founding Board Member of the U.S. Hereditary Angioedema Association.

DX-88

DX-88 is a small protein discovered by Dyax utilizing its proprietary phage display technology. DX-88 has exquisite specificity and affinity for kallikrein, a serine protease. Unihibited, kallikrein leads to the inflammatory cascade. In addition to being studied in phase II trials for its potential to treat HAE, DX-88 is in phase I/II clinical development for the prevention of blood loss and other systemic inflammatory responses (SIRS) during cardiothoracic surgery, an indication where kallikrein is also thought to be a relevant target.

Genzyme Corporation

Genzyme Corporation is a global biotechnology company dedicated to making a major positive impact on the lives of people with serious diseases and medical conditions. This commitment has driven innovation in treating both widespread diseases and rare genetic conditions, in providing leading diagnostic tests and services, in bringing the benefits of biotechnology to the practice of surgery, and in developing novel approaches to cancer. Genzyme's 5,700 employees worldwide serve patients in more than 80 countries.

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.

Dyax Corp.

Dyax Corp. is a biopharmaceutical company focused on the discovery, development and commercialization of therapeutic antibodies, small proteins and peptides to be used as anti-inflammatory agents and in oncology. Dyax currently has two recombinant proteins in phase II clinical trials. DX-88 is in phase II studies for the potential treatment of hereditary angioedema, and in phase I/II studies for use during cardiopulmonary bypass surgery. DX-890 is in phase II clinical trials for the potential treatment of cystic fibrosis.

Dyax uses its patented phage display technology to rapidly identify compounds that bind with high affinity and specificity to targets of interest, with the objective of advancing those with the greatest therapeutic potential into clinical development. Dyax leverages its technology broadly through revenue generating licenses and collaborations in therapeutics and in non-core areas of affinity separations, diagnostic imaging, and research reagents. Through its subsidiary, Biotage, Inc., Dyax develops, manufactures and sells its novel cartridge-based chromatography drug purification and separations systems as tools to speed the drug discovery process at pharmaceutical companies worldwide.

For more information on Dyax Corp., please visit www.dyax.com.

Genzyme Disclaimer

This press release contains forward-looking statements, including statements about: the potential use of DX-88 for HAE; plans to develop a treatment for HAE; the potential approval of DX-88 for HAE and additional indications; and commercialization plans. 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 efficacy and safety of DX-88 for HAE; the actual timing and results of clinical trials; the timing and content of submissions to and decisions made by regulatory authorities; 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 2002 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.

Genzyme(R) is a registered trademark of Genzyme Corp. All rights reserved.

Dyax Disclaimer

This press release contains forward-looking statements, including statements regarding the prospects for Dyax's clinical trials of DX-88 and its collaboration with Genzyme. Statements that are not historical facts are based on Dyax's current expectations, beliefs, assumptions, estimates, forecasts and projections for Dyax and the industry and markets in which Dyax competes. The statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict. Therefore, actual outcomes and results may differ materially from what is expressed in such forward-looking statements. Important factors which may affect our clinical trials, our research and development programs and our collaboration with Genzyme include the risks that; products from DX-88 may not show therapeutic effect or an acceptable safety profile in clinical trials or could take a significantly longer time to gain regulatory approval than Dyax expects or may never gain approval; Dyax will be dependent on the expertise, effort, priorities and contractual obligations of Genzyme in the development, clinical trials, manufacture, marketing, sales and distribution of DX-88; DX-88 may not gain market acceptance; Dyax may not be able to obtain and maintain intellectual property protection for its products and technologies; others may develop products superior to Dyax's products; and other risk factors described or referred to in Dyax's most recent Annual Report on Form 10-K and other periodic reports filed with the Securities and Exchange Commission. Dyax cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this release, and Dyax undertakes no obligation to update or revise these statements, except as may be required by law.

Dyax and the Dyax logo are registered trademarks of Dyax Corp. Biotage is a trademark of Biotage, Inc., a Dyax subsidiary.