Dyax Announces FDA Accepts for Review the Complete Response Submission for DX-88 in Hereditary Angioedema

Dyax Announces FDA Accepts for Review the Complete Response Submission for DX-88 in Hereditary Angioedema

CAMBRIDGE, Mass. -- Jun. 8, 2009-- Dyax Corp. announced today that the U.S. Food and Drug Administration (FDA) has accepted for review the Company's submission in response to the FDA's March 2009 Complete Response letter which outlined requirements for approval of DX-88 for the treatment of acute attacks of hereditary angioedema (HAE). In connection with the acceptance, the FDA assigned Dyax's BLA a new Prescription Drug User Fee Act (PDUFA) action date of December 1, 2009.

In the Complete Response letter, received March 25, 2009, the FDA requested submission of a Risk Evaluation and Mitigation Strategy (REMS) and additional information with respect to the chemistry, manufacturing and controls (CMC) section of the BLA. Dyax believes these issues are fully addressed in its reply, submitted June 1, 2009.

"We are confident that our proposed REMS for assuring the safe use of DX-88 and our response to other FDA requests thoroughly address the matters raised in the agency's letter," said Gustav A. Christensen, President and Chief Executive Officer of Dyax. "We will continue to work with the FDA during this final stage of review for DX-88 so this important therapy can be brought as expeditiously as possible to patients suffering from this devastating disease."

About DX-88 for HAE

The recombinant, small protein, DX-88 (ecallantide), was discovered utilizing Dyax's proprietary phage display technology and is being evaluated as a subcutaneous therapy for treating acute HAE attacks. DX-88 is a potent and selective plasma kallikrein inhibitor, a key mediator of inflammation in angioedema, and has demonstrated effectiveness for treating all attack locations, included life-threatening laryngeal attacks. DX-88 has been evaluated in five clinical trials for HAE, including two Phase 3 placebo-controlled trials, which represent the largest placebo-controlled evaluation of any therapeutic for this indication. A continuation trial is ongoing.

About HAE

Hereditary angioedema (HAE) is an acute inflammatory condition characterized by episodes of severe, often painful swelling affecting the extremities, the gastrointestinal tract, the genitalia, and in potentially life-threatening cases, the larynx. HAE is caused by low or dysfunctional levels of C1 esterase inhibitor (C1-INH), a naturally occurring molecule that inhibits plasma kallikrein, a key mediator of inflammation, and other serine proteases in the blood.

About Dyax

Dyax is focused on advancing novel biotherapeutics for unmet medical needs, with an emphasis on inflammatory and oncology indications. Dyax utilizes its proprietary drug discovery technology to identify antibody, small protein and peptide compounds for clinical development. Dyax's lead product candidate is DX-88 (ecallantide), a recombinant small protein that is currently being evaluated for its therapeutic potential in two separate indications. On June 1, 2009, Dyax submitted a response to the FDA's Complete Response letter regarding the review of Dyax's Biologics License Application (BLA) of DX-88 for the treatment of hereditary angioedema (HAE). The FDA accepted the submission and assigned Dyax's BLA a new Prescription Drug User Fee Act (PDUFA) action date of December 1, 2009. DX-88 has orphan drug designation in the U.S. and E.U., as well as Fast Track designation in the U.S., for this indication. Additionally, DX-88 is being evaluated in Phase 2 trials for the prevention of blood loss during on-pump cardiothoracic surgery (CTS), which are being conducted by Dyax's partner, Cubist Pharmaceuticals. Dyax licensed to Cubist the intravenous formulation of DX-88 for surgical indications in North America and Europe. DX-88 and other compounds in Dyax's pipeline were identified using its patented phage display technology, which rapidly selects compounds that bind with high affinity and specificity to therapeutic targets. Dyax leverages this technology broadly with over 70 revenue generating licenses and collaborations for therapeutic discovery, as well as in non-core areas such as affinity separations, diagnostic imaging, and research reagents. Dyax is headquartered in Cambridge, Massachusetts. For online information about Dyax Corp., please visit www.dyax.com.

Dyax Disclaimer

This press release contains forward-looking statements, including statements regarding the timing and prospects for review and FDA approval of the BLA for DX-88 for HAE, including the sufficiency of Dyax's response to the FDA's Complete Response letter. Statements that are not historical facts are based on Dyax's current expectations, beliefs, assumptions, estimates, forecasts and projections about 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 the prospects for review and FDA approval of the BLA for DX-88 for HAE include the risks that: DX-88 could take a significantly longer time to gain regulatory approval than Dyax expects or may never gain approval; others may develop technologies or products superior to DX-88 or that receive regulatory approval and are on the market before DX-88; DX-88 may not gain market acceptance; Dyax is dependent on the expertise, effort, priorities and contractual obligations of third parties in the manufacture, marketing, sales and distribution of DX-88; and other risk factors described or referred to Item 1A, "Risk Factors" 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 obligations to update or revise these statements, except as may be required by law.