Cinryze is Efficacious for Hereditary Angioedema (HAE) Attack Prevention in Pediatric Patients: Final Phase 3 Efficacy and Safety Results

C1 inhibitor (C1-INH; Shire, Lexington, MA, USA) is approved for the treatment and pre-procedural prevention of HAE attacks in patients aged ≥2 years (EU), and routine prevention of attacks in patients ≥6 years (EU) and ≥12 years (US). C1-INH’s safety and efficacy for attack prevention in children aged 6-11 years was investigated in a phase 3 study. The multicenter single-blind study required children to have an average of ≥1.0 angioedema monthly attacks that were moderate, severe, or required acute treatment during the 12-week baseline observation period. In a crossover design, patients received 500U and 1000U C1-INH every 3-4 days for 12 weeks. The primary endpoint was the monthly-normalized number of attacks (NNA). Of 12 enrolled patients (HAE type I), 7 (58.3%) were female with a median (range) age and BMI of 10.0 (7-11) years and 18.6 (13.1-28.2) kg/m2, respectively. NNA with 500U and 1000U differed significantly (mean [SD] within subject difference -0.4 [0.58]; P=0.035). The mean (SD) percent reduction in NNA compared to baseline (3.7 [3.2] attacks) was 71.1% (27.1%) and 84.5% (20.0%), respectively. Overall, 58.3% and 91.7% of patients achieved a ≥70% reduction from baseline with 500U and 1000U C1-INH, respectively. Cumulative attack severity, cumulative daily severity, and number of treatment-requiring acute attacks were reduced. There were no serious adverse events or discontinuations. Patient’s health status (EQ-5D Y) improved, particularly with 1000U C1-INH. As observed in prior C1-INH studies, 500U and 1000U C1-INH were effective, safe, and well-tolerated for routine prevention of HAE attacks in children aged 6-11 years.