Efficacy Study of DX-88 (Ecallantide) to Treat Acute Attacks of Hereditary Angioedema (HAE)

This is a randomized placebo-controlled trial.

The study is designed to assess the efficacy and safety of 30 mg subcutaneous ecallantide
versus placebo in the treatment of moderate to severe acute attacks of hereditary angioedema.
This study is conducted under Special Protocol Assessment with the FDA and is designed to
provide pivotal efficacy data on ecallantide. These data are intended to support the
marketing authorization of ecallantide in the treatment of acute attacks of hereditary
angioedema. Efficacy and safety of ecallantide will be evaluated in this study.

Inclusion Criteria:

- 10 years of age or older

- Executed informed consent

- Documented diagnosis of HAE (Type I or II)

- Presentation at the site within 8 hours of patient recognition of an moderate to
severe HAE acute attack

Exclusion Criteria:

- Receipt of an investigational drug or device, within 30 days prior to study treatment

- Receipt of non-investigational C1-INH within 7 days of treatment

- Receipt of DX-88 (ecallantide) within 3 days prior to study treatment

- Diagnosis of acquired angioedema (AAE), estrogen-dependent angioedema or drug-induced
angioedema (including angiotensin-converting enzyme inhibitor induced angioedema)

- Pregnancy or breastfeeding