Efficacy and safety of recombinant C1 inhibitor for the treatment of hereditary angioedema attacks: a North American open-label study

BackgroundThe efficacy of recombinant human C1 inhibitor (rhC1INH) for the treatment of patients with acute hereditary angioedema (HAE) attacks has been demonstrated in 2 randomized, double-blind, placebo-controlled studies.ObjectiveTo assess the safety and efficacy of rhC1INH for repeated treatment of acute attacks of HAE.MethodsIn this open-label extension study, patients with eligible HAE attacks were treated with an intravenous 50-U/kg dose of rhC1INH with an option for an additional dose of 50 U/kg based on clinical response. Time to beginning of relief was assessed by patients using a 100-mm visual analogue scale (VAS). Safety evaluation was based on the clinical laboratory results and adverse events.ResultsSixty-two patients were treated for 168 attacks (range, 1-8 attacks per patient). A total of 90% of the attacks were treated with a single 50-U/kg dose of rhC1INH. Median times to beginning of symptom relief for the first 5 attacks were 37 to 67 minutes. More than 90% of attacks responded within 4 hours after treatment with rhC1INH. There was no requirement for increased dosing with successive treatments. Thirty-nine patients (63%) reported at least 1 treatment-emergent adverse event, with most events rated mild to moderate. Seven severe treatment-emergent adverse events were reported, and all were considered to be unrelated to treatment with rhC1INH.ConclusionThe results of this open-label extension support continued efficacy of rhC1INH after repeated treatments for subsequent HAE attacks. There was no increase in adverse event reporting after repeated exposure to rhC1INH.Trial Registrationclinicaltrials.gov Identifier: NCT00225147