Management of acute attacks of hereditary angioedema: role of ecallantide

Abstract

Hereditary angioedema (HAE) is characterized as an episodic swelling disorder with autosomal dominant inheritance. Clinical features include nonpitting edema of external or mucosal body surfaces, and patients often present with swelling of the extremities, abdominal pain, and swelling of the mouth and throat, which can lead to asphyxiation. Patients with HAE classically have no associated urticaria, which is often referred to as nonhistaminergic angioedema. Treatment for HAE involves long-term prophylaxis, short-term prophylaxis, and management of acute attacks. Up until the past few years, acute HAE episodes were predominately treated with supportive measures. Three classes of medications have recently been approved by the US Food and Drug Administration (FDA) for the management of acute HAE attacks. Ecallantide, a recombinant protein that acts as a reversible inhibitor of kallikrein, is currently indicated for acute attacks of HAE in those aged ≥12 years. In two randomized, double-blind, placebo-controlled, multicenter trials, EDEMA3 and EDEMA4, patients treated with 30 mg of ecallantide demonstrated statistically significant improvement in symptoms compared to those on placebo. In addition to its use as treatment for HAE, ecallantide has been used off label in the management of nonhistaminergic angioedema, not due to HAE. Ecallantide has shown promise in the treatment of these other forms; however, data are limited to mainly case reports at this time. Ecallantide is generally a safe and well-tolerated medication; however, based on reports of anaphylaxis, ecallantide does contain a black box warning. Due to the risk of anaphylaxis, ecallantide cannot be self-administered and must be given by a health care professional. Overall, ecallantide is a safe and effective medication for the treatment of acute attacks of HAE.

Keywords: 7- C1-Inhibitor; ACE-Inhibitor induced angioedema; Kallikrein; acquired angioedema; bradykinin; idiopathic angioedema; nonhistaminergic angioedema.

Figure 1

The pathophysiology of bradykinin formation via the contact pathway. Notes: Functioning C1-INH inhibits the formation of bradykinin. ACE inhibitors impair the degradation of bradykinin. Abbreviations: ACE, angiotensin-converting enzyme; C1-INH, C1-inhibitor; fXII, factor XII; HMWK, high-molecular-weight kininogen.

Figure 2

Mechanisms of action of the drugs used for treatment of acute HAE attacks. Abbreviations: C1-INH, C1-inhibitor; fXII, factor XII; HAE, hereditary angioedema; HMWK, high-molecular-weight kininogen.