Preventing hereditary angioedema attacks in children using Cinryze®: interim efficacy and safety phase 3 findings

Background: Hereditary angioedema (HAE) is a rare genetic disease causing unpredictable and potentially life-threatening subcutaneous and submucosal edematous attacks. Cinryze® (Shire ViroPharma Inc., Lexington, MA, USA), a nanofiltered C1 inhibitor (C1-INH), is approved in Europe for the treatment, preprocedure prevention, and routine prophylaxis of HAE attacks, and for the routine prophylaxis of attacks in the USA. This phase 3 study assessed the safety and efficacy of 2 C1-INH doses in preventing attacks in children aged 6-11 years. Methods: A randomized single-blind crossover study was initiated in March 2014. Results for the first 6 patients completing the study are reported here. After a 12-week qualifying observation period, patients were randomly assigned to 1 of 2 C1-INH doses, 500 or 1,000 U, every 3-4 days for 12 weeks and crossed over to the alternative dose for a second 12-week period. The primary efficacy endpoint was the number of angioedema attacks per month. Results: Six females with HAE type I and a median age of 10.5 years received 2 doses of C1-INH (500 and 1,000 U). The mean (SD) difference in the number of monthly angioedema attacks between the baseline observation period and the treatment period was -1.89 (1.31) with 500 U and -1.89 (1.11) with 1,000 U. During the treatment periods, cumulative attack severity, cumulative daily severity, and the number of attacks needing acute treatment were lower. No serious adverse events or study drug discontinuations occurred. Conclusions: Interim findings from this study indicate that routine prevention with intravenous administration of C1-INH is efficacious, safe, and well tolerated in children ≥6 years of age

A randomized trial of human C1 inhibitor prophylaxis in children with hereditary angioedema

BACKGROUND: Patients with hereditary angioedema with C1 inhibitor deficiency or dysfunction have burdensome recurrent angioedema attacks. The safety, efficacy, and health-related quality of life (HRQoL) outcomes of C1 inhibitor (C1-INH) prophylaxis (intravenously administered) in patients aged 6-11 years were investigated. METHODS: Eligible patients were enrolled in a randomized, single-blind, crossover, phase 3 trial. After a 12-week baseline observation period (BOP), patients received 500 or 1000 U C1-INH, twice weekly, for 12 weeks before crossing over to the alternate dose for 12 weeks. The primary efficacy end-point was the monthly normalized number of angioedema attacks (NNA). HRQoL was assessed using the EuroQoL 5-dimensional descriptive system youth version and visual analog scale (EQ-VAS). RESULTS: Twelve randomized patients had a median (range) age of 10.0 (7-11) years. Mean (SD) percentage reduction in monthly NNA from BOP was 71.1% (27.1%) with 500 U and 84.5% (20.0%) with 1000 U C1-INH. Mean (SD) within-patient difference (-0.4 [0.58]) for monthly NNA with both doses was significant (P = 0.035 [90% CI, -0.706 to -0.102]). Cumulative attack severity, cumulative daily severity, and number of acute attacks treated were reduced. No serious adverse events or discontinuations occurred. Mean EQ-VAS change from BOP to week 9 of treatment (500 U C1-INH, 10.4; 1000 U C1-INH, 21.6) was greater than the minimal important difference, indicating a meaningful HRQoL change. CONCLUSIONS: C1-INH prophylaxis was effective, safe, and well tolerated in children aged 6-11 years experiencing recurrent angioedema attacks. A post hoc analysis indicated a meaningful improvement in HRQoL with C1-INH. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02052141