A Phase 3, Multicenter, Randomized, Placebo-controlled, Double-blind Study to Evaluate the Efficacy and Safety of Lanadelumab for Prevention Against Acute Attacks of Non-histaminergic Angioedema With Normal C1-Inhibitor (C1-INH)

The main aim of this study is to check if repeated subcutaneous (SC) injections of lanadelumab can prevent angioedema attacks in teenagers and adults with non-histaminergic angioedema with normal C1-INH. Another aim is to check if they tolerate the repeated SC injections.Participants will receive a SC injection of lanadelumab every two weeks for 26 weeks. The first two doses of lanadelumab will be given at the study clinic. Once a participant (and/or parent/caregiver) has been appropriately trained, lanadelumab can be self-injected. Visits to the study clinic are planned for the first, third and fourth week and then every 4 weeks.