Hereditary angioedema (HAE) is a genetic disorder resulting from low levels of C1-inhibitor
activity that manifests as acute attacks of variable and sometimes life-threatening
edema. Ecallantide is a novel potent inhibitor of human plasma kallikrein, a key mediator
of the excessive formation of bradykinin associated with the signs and symptoms of
an HAE attack.
To evaluate the efficacy and safety of ecallantide in the treatment of acute HAE attacks.
In this double-blind, placebo-controlled study, patients with a moderate to severe
HAE attack were randomized 1:1 to receive 30 mg of subcutaneous ecallantide or placebo.
The primary efficacy end point was change from baseline in mean symptom complex severity
score 4 hours after dosing. Additional end points included treatment outcome score
4 hours after dosing and maintenance of significant overall improvement through 24
Ninety-six patients were enrolled. Mean (SD) change from baseline in mean symptom
complex severity score 4 hours after dosing was significantly greater with ecallantide
use (-0.8 [0.6]) compared with placebo use (-0.4 [0.8]) (P = .01 comparing distributions).
Ecallantide therapy was also associated with a significantly larger mean (SD) treatment
outcome score 4 hours after dosing vs placebo use (ecallantide: 53.4 [49.7]; placebo:
8.1 [63.2]; P = .003 comparing distributions). The benefit of ecallantide was apparent
within 2 hours after dosing and was maintained through 24 hours after dosing. The
safety profile was similar between the treatment groups.
Ecallantide appears to be an effective and safe treatment for acute attacks of HAE.