C1 Esterase Inhibitor (C1INH-nf) for the Treatment of Acute Hereditary Angioedema (HAE) Attacks

Randomized subjects treated for a qualifying attack were eligible to receive rescue dosing with 1,000 U of C1INH-nf if they did not achieve beginning of substantial relief of the defining symptom within 4 hours after initial treatment with blinded study drug, or if at any time the attack progressed to include airway compromise. A second 1,000 U rescue dose was permitted 60 minutes after the initial rescue dose, if necessary.

The study design also allowed for administration of open-label C1INH-nf for laryngeal angioedema attacks, which were non-randomizable events due to the presence of or potential for airway compromise (immediate 1,000 U dose of C1INH-nf, repeated after 60 minutes, if necessary). In addition, subjects were eligible to receive open-label C1INH-nf (1,000 U single dose) prior to emergency surgical (non-cosmetic) procedures.

A total of 83 subjects were enrolled in the study. Seventy-one (71) subjects experienced qualifying attacks and were randomized to blinded study drug (36 C1INH-nf, 35 placebo); only the 71 randomized subjects were analyzed for efficacy. An additional 12 subjects were never randomized but received open-label C1INH-nf for treatment of laryngeal angioedema and/or prior to emergency surgical procedures. Of the 35 subjects randomized to placebo, 23 also received C1INH-nf (eg, rescue, open-label). In total, 83 subjects received at least 1 dose of study drug and were analyzed for safety; 71 subjects were exposed to C1INH-nf (59 randomized, 12 open-label only) and 12 subjects were exposed only to placebo.