Dyax Corp.
Jun 7, 2010

Dyax Announces Publication of KALBITOR® (ecallantide) EDEMA4® Trial Results in the Annals of Allergy, Asthma, and Immunology

Benefit of KALBITOR for Acute HAE Attack Symptoms Demonstrated at Four Hours Post-Treatment

CAMBRIDGE, Mass., Jun 07, 2010 (BUSINESS WIRE) --Dyax Corp. (NASDAQ: DYAX) announced today the publication of results from its second Phase 3, placebo-controlled trial, known as EDEMA4®, evaluating KALBITOR (ecallantide) for the treatment of acute attacks of hereditary angioedema (HAE). The results, published in the June 2010 issue of the Annals of Allergy, Asthma, and Immunology, indicate that KALBITOR is effective in ameliorating HAE attacks, resolving associated symptoms and preventing attack progression. KALBITOR, a selective plasma kallikrein inhibitor that was discovered and developed by Dyax, is available in the U.S. for the treatment of acute attacks of HAE in patients 16 years of age and older.

KALBITOR treatment resulted in statistically significant improvement of symptoms over placebo at four hours post dosing, as measured by two HAE-specific, patient-reported outcome measures: change in Mean Symptom Complex Severity (MSCS) score (KALBITOR = -0.8 versus placebo = -0.4; P=0.01) and the mean Treatment Outcome Score (TOS) (KALBITOR = 53.4 versus placebo = 8.1; P=0.003). Treatment with KALBITOR also demonstrated significant improvement over placebo at 24 hours post dosing, as measured by change in MSCS score (KALBITOR = -1.5 versus placebo = -1.1; P=0.04) and TOS (KALBITOR = 88.8 versus placebo = 55.1; P=0.03).

The overall safety profile of KALBITOR observed in EDEMA4 was similar to that of placebo. The most common treatment-emergent adverse events (nausea, headache, and dizziness) were mild or moderate and occurred at a similar proportion in both the KALBITOR and placebo-treated groups. No serious adverse events were reported in the KALBITOR-treated group and no KALBITOR-treated patients developed symptoms suggestive of hypersensitivity.

"The EDEMA4 study has demonstrated that KALBITOR reduces symptoms of acute attacks of swelling associated with HAE within just 4 hours post dosing, sustaining the effect at 24 hours post dosing," stated Dr. Robyn J. Levy, of the Family Allergy & Asthma Research Center in Atlanta, Georgia and lead author and principal investigator of the EDEMA4 trial. "Since acute attacks of HAE tend to worsen over the first 24 hours, treatment with an effective therapy such as Kalbitor is important for symptom management. EDEMA4 data also suggest that the benefit seen with KALBITOR begins a few hours after dosing."

Mean TOS scores at 1, 2, and 3 hours post dosing were also analyzed. The KALBITOR treatment group experienced a clinically meaningful trend toward greater improvement (represented by increasing TOS) versus the placebo group at 1 hour (TOS: KALBITOR = 20.7 versus placebo = 8.2; P=0.351) and 2 hours (TOS: KALBITOR = 30.9 versus placebo = 6.8; P=0.074) and statistically significant improvement at 3 hours (TOS: KALBITOR = 44.1 versus placebo = 5.7; P=0.007).

Emerging symptoms were observed more frequently among the placebo-treated patients (14.6%) compared to the KALBITOR-treated group (4.2%). Moreover, of these, three placebo-treated patients reported emerging laryngeal symptoms, while zero emerging laryngeal symptoms were reported from the KALBITOR-treated patients.

While in EDEMA4 no serious adverse events or symptoms suggestive of hypersensitivity were reported in the KALBITOR-treated group, in the overall KALBITOR clinical program, hypersensitivity was reported after administration with KALBITOR. As part of product approval, Dyax has implemented a Risk Evaluation and Mitigation Strategy (REMS) program, consisting of a Medication Guide and communication plan. The goal of the REMS is to communicate the risk of anaphylaxis and the importance of distinguishing between a hypersensitivity reaction and HAE attack symptoms.

Summary of EDEMA4

EDEMA4 is the second of two Phase 3 trials conducted by Dyax for evaluating a 30 mg subcutaneous KALBITOR (ecallantide) to treat acute attacks of HAE. The 96-patient, double-blind, placebo-controlled, multi-center trial was conducted in the United States and Canada.

The primary objective of EDEMA4 was to determine the efficacy and safety of the fixed 30 mg subcutaneous dose of KALBITOR for patients suffering from moderate to severe acute HAE attacks. Two HAE-specific patient reported outcome (PRO) measures were developed to assess efficacy endpoints: Mean Symptom Complex Severity (MSCS) score, a point-in-time assessment of individual symptom burden that accounts for symptom location and severity of the attack using a score from 0 to 3 (0=normal, 3=severe) and Treatment Outcome Score (TOS), a composite measure of treatment response based on a scale of 100 to -100 (100=significant improvement, -100 significant worsening) and taking into account symptom severity at baseline.

About HAE

Hereditary angioedema (HAE) is a rare acute inflammatory condition characterized by episodes of severe, often painful swelling affecting the extremities, the gastrointestinal tract, the genitalia, and 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. HAE is estimated to affect 1:10,000 to 1:50,000 individuals. Learn more at http://www.HAEHope.com.

About KALBITOR®(ecallantide)

KALBITOR is a plasma kallikrein inhibitor indicated for the treatment of acute attacks of hereditary angioedema (HAE) in patients 16 years of age and older. KALBITOR, which was discovered and developed by Dyax, is the first subcutaneous treatment available in the U.S. for treating acute HAE attacks.

Important KALBITOR Safety Information

Anaphylaxis has been reported after administration of KALBITOR. Because of the risk of anaphylaxis, KALBITOR should only be administered by a healthcare professional with appropriate medical support to manage anaphylaxis and hereditary angioedema. Healthcare professionals should be aware of the similarity of symptoms between hypersensitivity reactions and hereditary angioedema and patients should be monitored closely. KALBITOR should not be administered to patients with known clinical hypersensitivity to KALBITOR.

For more information about KALBITOR, including full prescribing information, visit http://www.KALBITOR.com.


Patients and healthcare providers can contact KALBITOR AccessSM to receive information and work with program staff to research patient insurance coverage for KALBITOR. KALBITOR Access is designed as a one-stop point of contact for information about KALBITOR. The program is staffed with dedicated insurance specialists and nurse case managers who will help coordinate patient treatment and access to KALBITOR. Patients and healthcare providers can call 1-888-4KALBITOR (1-888-452-5248) for information and to utilize these services or visit http://www.kalbitor.com/index.html.

About Dyax

Dyax is a fully integrated biopharmaceutical company focused on discovering, developing and commercializing novel biotherapeutics for unmet medical needs. Dyax utilizes its proprietary drug discovery technology to identify antibody, small protein and peptide compounds for clinical development. Our lead product, DX-88, has been approved under the brand name KALBITOR® (ecallantide) in the United States for the treatment of acute attacks of hereditary angioedema in patients 16 years of age and older.

In addition to its approved commercial use, DX-88 is also being evaluated for its therapeutic potential in other angioedema indications (acquired and ACE inhibitor-induced angioedemas) and, through a collaboration with Fovea Pharmaceuticals (a subsidiary of sanofi aventis), is in a Phase 1 trial for retinal vein occlusion-induced macular edema.

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 http://www.dyax.com.

Dyax Disclaimer

This press release contains forward-looking statements, including statements regarding the prospects for therapeutic benefits and treatment advantages of KALBITOR for HAE. 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 therapeutic benefits and treatment advantages of KALBITOR for HAE include the risks that: others may develop technologies or products superior to KALBITOR or that are on the market before KALBITOR; KALBITOR 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 KALBITOR; 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.

Dyax, the Dyax logo and KALBITOR are registered trademarks and EDEMA3 and EDEMA4 are registered service marks of Dyax Corp. KALBITOR Access is a service mark of Dyax Corp.

1. Levy RJ, Lumry WR, McNeil DL, et al. EDEMA4®: A phase 3, double-blind study of subcutaneous ecallantide for acute attacks of hereditary angioedema. Ann Allergy Asthma Immunol. 2010;104;523-529.

SOURCE: Dyax Corp.

Dyax Corp.
Ivana Magovcevic-Liebisch, 617-250-5759
Executive Vice President Corporate
Development and General Counsel
Nicole Jones, 617-250-5744
Director, Investor Relations and
Corporate Communications