SPRING STUDY: An Open-Label, Multicenter, Phase 3 Study to Evaluate the Safety, Pharmacokinetics, and Pharmacodynamics of Lanadelumab for Prevention Against Acute Attacks of Hereditary Angioedema (HAE) in Pediatric Subjects 2 to <12 Years of Age

The main aims of this study are to learn how lanadelumab moves through a child's body and if the children have any medical problems from lanadelumab. Other aims are to learn if prophylactic treatment with lanadelumab reduces the number and severity of HAE attacks in children, how lanadelumab affects the child's body, and if the children develop antibodies to lanadelumab.The study doctors will treat acute HAE attacks according to their standard practice.Participants will receive lanadelumab for up to 52 weeks. When they start treatment, participants will visit their clinic every week for the first 4 weeks. Then, they will visit their clinic every 4 weeks during treatment.