DX-88 Trials in Hereditary Angioedema To Be Featured at 4th European C

    Business Editors/Medical Editors
    European C1-INH Deficiency Workshop
    BIOWIRE2K

    CAMBRIDGE, Mass.--(BUSINESS WIRE)--April 29, 2005--Dyax Corp. (Nasdaq:DYAX) today announced the presentation of three oral abstracts at the 4th European C1-INH Deficiency Workshop that highlight collective results from the Company's clinical trials of DX-88 (ecallantide) for the treatment of hereditary angioedema (HAE). The Workshop is being held in Budapest, Hungary from April 29 through May 1, 2005. The abstracts will be presented in consecutive order, beginning at 10:30 am (GMT) on May 1, by the following DX-88 investigators: Dr. Marco Cicardi, M.D., University of Milan; Dr. Bruce Zuraw, M.D., University of California San Diego; and Dr. Timothy Craig, D.O., Penn State University. The presentations will feature positive results from three Phase II trials that demonstrate DX-88's tolerability and ability to elicit rapid and durable clinical responses in HAE patients. DX-88, which was discovered at Dyax and is being developed in a joint venture with Genzyme Corporation, is the most advanced investigational drug in the U.S. for the treatment of acute attacks of HAE.
    Dr. Marco Cicardi, M.D., a well-known expert in the clinical management of patients with HAE, will present on the topic of "DX-88 Clinical Experience Across EDEMA Trials by Location of HAE Attack." The findings demonstrate that all types of HAE attacks can be successfully treated with DX-88. Notably, life-threatening laryngeal attacks of HAE have responded particularly well; 94% of 18 laryngeal attacks analyzed to date experienced onset of symptom relief in a median response time of 27 minutes post-dosing with DX-88.
    Dr. Bruce Zuraw, M.D. will present "A Multicenter, Double-Blind Placebo-Controlled Study of DX-88 in Hereditary Angioedema: Results of the EDEMA1 study." Final results from this trial showed a statistically significant benefit for patients treated with DX-88 versus placebo; 72% of patients treated with DX-88 (n=40) reported significant improvement of HAE symptoms within four hours of administration, as opposed to 25% of patients within the placebo group (n=8), a difference of 47% (p=0.0169). Across all types of attacks in the trial, the median time to response (onset of significant relief of symptoms) was 70 minutes for the DX-88 group as compared to 246 minutes for the placebo group. Patient participants ranged from 10 to 75 years of age.
    Dr. Timothy Craig, D.O. will present "A Multicenter, Open Label, Repeat Dosing of DX-88 in HAE: Interim Results of the EDEMA2 Study." EDEMA2 is an ongoing, open label, Phase II repeat dosing study to evaluate the safety and efficacy of DX-88 when administered to patients multiple times for separate HAE attacks. Interim results based on the first 61 attacks treated highlight that DX-88 is well tolerated and can elicit rapid clinical responses, with a median time to initial response (onset of relief of symptoms) of 35 minutes. DX-88 has also retained its clinical effect on repeat treatment for separate HAE attacks. The maximum number of attacks treated to date in any one patient is 14, and this patient continues to respond well. To date, 133 HAE attacks have been treated in 49 patients at 24 active EDEMA2 trial sites.
    "I would like to recognize Drs. Cicardi, Zuraw and Craig for the time and effort they are devoting to DX-88 at this important HAE symposium. We are mutually committed to advancing an effective treatment for HAE patients who are suffering the debilitating effects of this unpredictable condition," commented Henry E. Blair, Chairman, President and CEO of Dyax Corp. He continued, "Our goal is to deliver a treatment that can be dosed easily and comfortably, in order to give patients direct control over their attacks and greatly improve their quality of life. With our strong and supportive network of HAE patients and physicians, I am confident that Dyax, with our partner Genzyme, will advance DX-88 as the first and best treatment option in the U.S."

    DX-88 Trials in HAE and Cumulative Data

    To date, Dyax has successfully completed two Phase II trials (EDEMA0 and EDEMA1), and is conducting one active Phase II trial (EDEMA2) of DX-88 in HAE. In these trials, over 185 doses of DX-88 have been administered to over 85 HAE patients by a 10-minute IV infusion.
    Based on positive animal study results, the Company has recently begun a Phase I safety and pharmacokinetics study using a subcutaneous formulation of DX-88 in human volunteers. Data from this trial is expected to support the Company's plans to conduct its pivotal Phase III trial using this easily administered formulation.
    DX-88 for the treatment of HAE has orphan drug designation in the U.S. and Europe, as well as Fast Track designation in the U.S.

    The C1-INH Workshop

    The C1-INH Workshop seeks to gather patient associations and pharmaceutical companies to discuss current views of hereditary and acquired angioedema, including recent progress in molecular diagnoses and novel therapeutic approaches to HAE.

    Hereditary Angioedema (HAE)

    HAE is a rare inherited condition characterized by episodes of acute swelling and inflammation that can peripherally affect the extremities (hands, feet, face), the abdominal tract, the genitalia, and in life-threatening cases, the larynx. Severe facial edema can also progress to the larynx.
    The prevalence of hereditary angioedema is believed to be between 1/10,000 and 1/50,000 people worldwide. The condition is caused by a genetic deficiency of C1 esterase inhibitor (C1-INH), a naturally occurring molecule that inhibits kallikrein and other serine proteases in the blood.
    Abdominal obstruction caused by HAE is often associated with bouts of severe pain, nausea, and vomiting caused by swelling in the intestinal wall. Peripheral attacks are the most physically disfiguring, yet all types of HAE attacks are debilitating. On average, patients have 12 HAE attacks per year which, if left untreated, endure for two to five days. The inconsistent nature of HAE attacks contributes to the patients' sense of uncertainty and the fear of having a laryngeal attack that can rapidly close the airways.

    Current Treatment of HAE

    There is no marketed therapy for acute attacks of HAE in the United States. Adult HAE patients often manage the frequency of attacks with the long-term use of anabolic steroids.
    In some European countries, plasma derived C1-Inhibitor is available. However, as with all plasma based products, C1-INH carries the potential risk of blood-borne viruses and is also a non-specific inhibitor of kallikrein.
    DX-88 is a recombinant small protein that inhibits kallikrein in vitro with very high affinity (40 pM Ki) and unlike C1-INH, does not inhibit any of the other serine proteases against which it was tested. Kallikrein may be the most relevant target in HAE, as it is a key enzyme in the inflammatory cascade, in which it liberates bradykinin, the intermediary of pain and swelling associated with HAE. The compound was discovered at Dyax Corp. and is being developed for the treatment of HAE in a joint venture between Dyax Corp. and Genzyme Corporation.

    Dyax Disclaimer

    This press release contains forward-looking statements, including statements regarding the potential therapeutic benefit of DX-88 for HAE, the timelines for its future clinical trials, and the prospects for regulatory developments regarding DX-88 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 potential therapeutic benefit of DX-88 for HAE, the timelines for its future clinical trials, and the prospects for regulatory developments regarding DX-88 for HAE include the risks that: DX-88 for HAE 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; others may develop technologies or products for HAE superior to DX-88; Dyax is dependent on the expertise, effort, priorities and contractual obligations of third parties in the clinical trials, manufacture, marketing, sales and distribution of DX-88; DX-88 may not gain market acceptance for HAE; Dyax may not be able to obtain and maintain intellectual property protection for DX-88 for the duration of its patent covering DX-88; 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 obligations to update or revise these statements, except as may be required by law.

    Dyax and the Dyax logo are the registered trademarks of Dyax Corp.

    EDEMA0, EDEMA1 and EDEMA2 are trademarks of Dyax Corp.

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CONTACT: Dyax Corp. Sondra Henrichon, 617-250-5839 Director Investor Relations and Corporate Communications shenrichon@dyax.com

KEYWORD: MASSACHUSETTS HUNGARY INTERNATIONAL EUROPE TRACK INDUSTRY KEYWORD: PHARMACEUTICAL MEDICAL BIOTECHNOLOGY TRADESHOW PRODUCT SOURCE: Dyax Corp.

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