Ecallantide: a plasma kallikrein inhibitor for the treatment of acute attacks of hereditary angioedema.

Hereditary angioedema (HAE) is a debilitating, potentially fatal disease characterized by variable and unpredictable acute attacks of swelling affecting the subcutaneous tissue and mucosa. It is an autosomal dominant disorder resulting from a genetic deficiency of functional C1-esterase inhibitor. Available treatments include long-term prophylaxis, short-term prophylaxis and treatment of acute attacks. Ecallantide is a novel, specific and potent inhibitor of plasma kallikrein that was recently approved in the United States for the treatment of acute attacks of HAE in patients aged 16 years and older. In two phase III clinical trials, the subcutaneous administration of 30 mg ecallantide resulted in significantly greater symptom improvement than placebo for acute attacks of HAE. Ecallantide was generally well tolerated throughout the clinical development program. The main safety concern following ecallantide treatment is hypersensitivity reactions, including anaphylaxis. A Risk Evaluation and Management Strategy (REMS) has been implemented to minimize this risk and a long-term observational safety study is currently under way to collect more information about hypersensitivity and immunogenicity. Ecallantide represents a novel treatment option for patients with HAE.