Data demonstrating effectiveness of KALBITOR to treat acute HAE presented at AAAAI 2010 Annual Meeting

Data demonstrating the effectiveness of KALBITOR (ecallantide) to treat hereditary angioedema (HAE) acute attacks by primary attack location were provided in an oral presentation yesterday at the American Academy of Allergy, Asthma and Immunology (AAAAI) 2010 Annual Meeting in New Orleans. KALBITOR, discovered and developed by Dyax Corp. (NASDAQ:DYAX), was approved by the U.S. Food and Drug Administration (FDA) late last year and is indicated for the treatment of acute attacks of HAE in patients 16 years of age or older.

“Importantly, time to complete or near-complete symptom resolution for abdominal and laryngeal attacks was reached by 4 hours for 65.2 % and 60.0% of ecallantide-treated patients versus 31.7% and 11.1% of placebo-treated patients, respectively.”

Efficacy endpoints assessed at 4 hours post-dosing for peripheral, abdominal and laryngeal attacks included two, HAE-specific, patient-reported outcome measures: Mean Symptom Complex Severity (MSCS) score and Treatment Outcome Score (TOS). Time to significant improvement was also assessed at 4 hours.

“HAE is a complex disease with varying anatomic locations affected during each acute attack. By stratifying the data by attack location, we were able to discern the effect of treatment during each episode at each affected location,” stated Patrick Horn, MD, PhD, Vice President of Clinical and Medical Affairs at Dyax Corp. and one of the study authors.

Statistically significant improvement of symptoms, when analyzed by attack location, was demonstrated with KALBITOR treatment versus placebo based on TOS at 4 hours (peripheral:>

In time to complete or near-complete symptom resolution, KALBITOR treatment was significantly better than placebo for abdominal>

“There was a striking difference between ecallantide and placebo in the time to complete or near-complete symptom resolution for the abdominal and laryngeal specific attack locations,” noted Marc Riedl, MD, MS, Assistant Professor of Clinical Immunology and Allergy at the David Geffen School of Medicine at UCLA in Los Angeles, and a study investigator. “Importantly, time to complete or near-complete symptom resolution for abdominal and laryngeal attacks was reached by 4 hours for 65.2 % and 60.0% of ecallantide-treated patients versus 31.7% and 11.1% of placebo-treated patients, respectively.”

A total of 143 patients from the EDEMA3 double blind and EDEMA4 studies were included in this analysis>

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.

Also presented at AAAAI were three poster presentations highlighting KALBITOR efficacy and safety information from Dyax’s HAE clinical development program, which included results from the Company’s two placebo-controlled Phase 3 trials, known as EDEMA3^® and EDEMA4^®, and the first-time presentation of data from the ongoing open-label, continuation study.

Complete List of Presentations at AAAAI 2010

Oral Presentations

• Ecallantide Treatment for Acute Attacks of HAE by Primary Attack Location– Patrick T. Horn, MD, PhD, Dyax Corp. – Monday, March 1, 2010, 2:30 PM

Poster Presentations

• Efficacy of Ecallantide for Acute HAE Attacks Is Maintained Across Multiple Treatments: Results from the EDEMA Development Program – William R. Lumry, MD, AARA Research Center,
  Dallas – Monday, March 1, 2010, 9:45 AM
• Hypersensitivity Reactions Following Ecallantide Treatment for Acute Attacks of HAE – William R. Lumry, MD, AARA Research Center, Dallas – Monday, March 1, 2010, 9:45 AM
• Interim Results from Continuation: the Ongoing, Open-Label, Extension Study of Ecallantide for the Treatment of Acute Attacks of Hereditary Angioedema– Andrew J. MacGinnitie, MD, PhD, Children’s Hospital of Pittsburgh of UPMC – Monday, March 1, 2010, 9:45 AM