Evaluation of DX-88 to resolve symptoms of acute HAE attacks to be presented

An analysis demonstrating the ability of DX-88 (ecallantide) to resolve symptoms of acute hereditary angioedema (HAE) attacks in all anatomic locations and to sustain effect will be presented in an oral presentation this week at the American College of Allergy, Asthma and Immunology (ACAAI) 2009 Annual Meeting in Miami Beach. This evaluation, and two others to be presented, highlight efficacy and safety analyses from the integrated analysis of the two Phase 3 placebo-controlled trials, EDEMA3^® and EDEMA4^®, of DX-88, the lead product candidate of Dyax Corp. (NASDAQ:DYAX), for the treatment of acute attacks of HAE.

In the time to response to treatment analysis, a statistically significant effect over placebo was achieved with DX-88 for two key endpoints: time to sustained improvement (improvement that endured for at least 45 minutes within 4 hours of dosing)>

The time of response of the clinical effect appeared to vary with location of the angioedema attack. Abdominal attacks, typically the most painful, and laryngeal attacks, which can be potentially life-threatening, improved more rapidly than peripheral attacks, demonstrating a significant benefit of DX-88 over placebo within 4 hours. The therapeutic effect of DX-88 in peripheral attacks was apparent by 24 hours.

“Positive findings from the clinically stringent hurdle of complete or near complete resolution of an HAE attack provide encouraging evidence that treatment with DX-88 can potentially offer patients a quick and durable treatment for what is often a debilitating attack that can last for several days if untreated,” commented Marc Riedl, MD, MS, Assistant Professor of Clinical Immunology and Allergy at the David Geffen School of Medicine at UCLA in Los Angeles. “Of even greater importance is that a rapid response was seen for laryngeal attacks, which can be life-threatening.”

A second oral presentation provides data on the pediatric experience of DX-88 for treating acute attacks of HAE. A total of 40 acute HAE attacks were treated with subcutaneously-administered DX-88 in 17 pediatric patients. For these patients, individual attack data were compared to the outcomes for the population receiving the corresponding DX-88 dose in the same study (called the reference group).

Symptom improvement, as measured by change in two patient-reported outcomes measures – Mean Symptom Complex Severity (MSCS) score and Treatment Outcome Score (TOS) – were better than or equal to that for the reference group in 75% and 78%, respectively, of acute attacks in pediatric patients four hours after treatment with DX-88. Time to onset of improvement (median: 37 minutes) and time to near complete resolution (median: 82.5 minutes) were shorter than or equal to that for the reference group in 58% and 63%, respectively, of acute attacks. There was a low rate of treatment-related adverse events in pediatric patients treated with 30 mg subcutaneous DX-88. Although hypersensitivity was observed in two pediatric patients treated with intravenous DX-88, no hypersensitivity was observed in the pediatric population following subcutaneous dosing. The efficacy and safety profiles for pediatric patients appeared similar to that of the overall treatment group.

Complete List of Presentations on DX-88 at ACAAI 2009

Oral Presentations

• Time to Response with Ecallantide for the Treatment of Acute Attacks of Hereditary Angioedema: Results from the EDEMA Development Program – Marc Riedl, MD, MS, David Geffen School of Medicine at UCLA – Monday, November 9, 2009, 1:00 PM
• Ecallantide for the Treatment of Acute Attacks of Hereditary Angioedema in Pediatric Patients: Experience in the EDEMA Development Program – Andrew J. MacGinnitie, MD, PhD, Children’s Hospital of Pittsburgh of UPMC – Monday, November 9, 2009, 1:45 PM

Poster Presentations

• Time of Intervention with Ecallantide for the Treatment of Acute Attacks of Hereditary Angioedema: Results from the EDEMA Development Program – Erin Banta, MD, Milton S. Hershey Medical Center, Hershey, PA – Saturday, November 7, 2009 and Sunday, November 8, 2009
• Successful Use of Ecallantide After an Anaphylactoid Reaction – Henry Li, MD, PhD, FAAAAI, Institute for Asthma and Allergy at Wheaton and Chevy Chase, MD – Saturday, November 7, 2009 and Sunday, November 8, 2009