RationaleHereditary angioedema (HAE) is an autosomal dominant disorder characterized by recurring and unpredictable attacks of angioedema. Ecallantide, a plasma-kallikrein inhibitor, is approved for treatment of acute attacks of HAE. Patients could enroll in multiple ecallantide trials including EDEMA3 and EDEMA4 (both placebo-controlled) and Continuation (open-label). This post hoc study assesses the efficacy and safety of ecallantide in patients who were treated, for comparable HAE attacks, with placebo in one study and ecallantide in another.MethodsPatient episodes treated with placebo in EDEMA3 or EDEMA4 were matched with episodes (same patient, same primary attack location, similar severity level) treated with ecallantide in Continuation. Efficacy comparisons included Treatment Outcome Score (TOS), Mean Symptom Complex Severity (MSCS) score, and time to complete or near-complete symptom resolution. Safety was assessed by treatment emergent adverse events.ResultsThe analysis includes 36 patients, each with 1 placebo-treated and 1 matched ecallantide-treated attack. At 4 hours, the ecallantide-treated episodes had greater improvement compared to placebo based on TOS (P <0.001) and change in MSCS score (P<0.001). By 4 hours, complete or near-complete symptom resolution was reached in 24 (66.7%) episodes treated with ecallantide compared to 8 (22.2%) episodes treated with placebo (P<0.001). The majority of patients showed greater improvement in their ecallantide-treated attack compared to their placebo-treated attack: 24 (67%) based on TOS, 25 (69%) based on MSCS score. Safety profiles appeared similar across the 2 groups of episodes.ConclusionsIn this longitudinal analysis, patients showed significantly better improvement and comparable safety following treatment with ecallantide versus placebo. RationaleHereditary angioedema (HAE) is an autosomal dominant disorder characterized by recurring and unpredictable attacks of angioedema. Ecallantide, a plasma-kallikrein inhibitor, is approved for treatment of acute attacks of HAE. Patients could enroll in multiple ecallantide trials including EDEMA3 and EDEMA4 (both placebo-controlled) and Continuation (open-label). This post hoc study assesses the efficacy and safety of ecallantide in patients who were treated, for comparable HAE attacks, with placebo in one study and ecallantide in another. Hereditary angioedema (HAE) is an autosomal dominant disorder characterized by recurring and unpredictable attacks of angioedema. Ecallantide, a plasma-kallikrein inhibitor, is approved for treatment of acute attacks of HAE. Patients could enroll in multiple ecallantide trials including EDEMA3 and EDEMA4 (both placebo-controlled) and Continuation (open-label). This post hoc study assesses the efficacy and safety of ecallantide in patients who were treated, for comparable HAE attacks, with placebo in one study and ecallantide in another. MethodsPatient episodes treated with placebo in EDEMA3 or EDEMA4 were matched with episodes (same patient, same primary attack location, similar severity level) treated with ecallantide in Continuation. Efficacy comparisons included Treatment Outcome Score (TOS), Mean Symptom Complex Severity (MSCS) score, and time to complete or near-complete symptom resolution. Safety was assessed by treatment emergent adverse events. Patient episodes treated with placebo in EDEMA3 or EDEMA4 were matched with episodes (same patient, same primary attack location, similar severity level) treated with ecallantide in Continuation. Efficacy comparisons included Treatment Outcome Score (TOS), Mean Symptom Complex Severity (MSCS) score, and time to complete or near-complete symptom resolution. Safety was assessed by treatment emergent adverse events. ResultsThe analysis includes 36 patients, each with 1 placebo-treated and 1 matched ecallantide-treated attack. At 4 hours, the ecallantide-treated episodes had greater improvement compared to placebo based on TOS (P <0.001) and change in MSCS score (P<0.001). By 4 hours, complete or near-complete symptom resolution was reached in 24 (66.7%) episodes treated with ecallantide compared to 8 (22.2%) episodes treated with placebo (P<0.001). The majority of patients showed greater improvement in their ecallantide-treated attack compared to their placebo-treated attack: 24 (67%) based on TOS, 25 (69%) based on MSCS score. Safety profiles appeared similar across the 2 groups of episodes. The analysis includes 36 patients, each with 1 placebo-treated and 1 matched ecallantide-treated attack. At 4 hours, the ecallantide-treated episodes had greater improvement compared to placebo based on TOS (P <0.001) and change in MSCS score (P<0.001). By 4 hours, complete or near-complete symptom resolution was reached in 24 (66.7%) episodes treated with ecallantide compared to 8 (22.2%) episodes treated with placebo (P<0.001). The majority of patients showed greater improvement in their ecallantide-treated attack compared to their placebo-treated attack: 24 (67%) based on TOS, 25 (69%) based on MSCS score. Safety profiles appeared similar across the 2 groups of episodes. ConclusionsIn this longitudinal analysis, patients showed significantly better improvement and comparable safety following treatment with ecallantide versus placebo. In this longitudinal analysis, patients showed significantly better improvement and comparable safety following treatment with ecallantide versus placebo.