Primary Outcome Measure(s): Number of Participants with Adverse Events Including Serious Adverse Events (SAE) and Adverse Events of Special Interest (AESI) [Time Frame: From start of study treatment up to Follow up (Day 392)]
Plasma Concentrations of Lanadelumab Over the Treatment Period [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Maximum Observed Concentration at Steady State (Cmax,ss) of Lanadelumab in Plasma [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Average Concentration Over Dosing Interval at Steady State (Cavg,ss) of Lanadelumab in Plasma [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Predose Concentration at Steady State (Ctrough,ss) of Lanadelumab in Plasma [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Time to Reach Maximum Observed Concentration (Cmax) (tmax)of Lanadelumab in Plasma [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Area Under the Concentration-Time Curve Over the Dosing Interval at Steady State (AUCtau,ss) of Lanadelumab in Plasma [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Terminal half-life (t1/2) of Lanadelumab in Plasma [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Apparent clearance (CL/F) of Lanadelumab [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Apparent Volume of Distribution (V/F) of Lanadelumab [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Secondary Outcome Measure(s): Normalized Number of Investigator-Confirmed Hereditary Angioedema (HAE) Attacks During Overall Treatment Period [Time Frame: From start of study treatment up to Follow up (Day 392)]
Normalized Number of Investigator-Confirmed HAE Attacks For Each Efficacy Evaluation Period Other Than the Overall Treatment Period [Time Frame: Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Time to the First Investigator-Confirmed Hereditary Angioedema (HAE) Attack for Each Evaluation Period [Time Frame: Day 0 through Day 364, Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Normalized Number of Hereditary Angioedema (HAE) Attacks Requiring Acute Treatment for Each Efficacy Evaluation Period [Time Frame: Day 0 through Day 364, Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Normalized Number of Moderate or Severe Investigator-Confirmed Hereditary Angioedema (HAE) Attacks for Each Efficacy Evaluation Period [Time Frame: Day 0 through Day 364, Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Normalized Number of High Morbidity Investigator-Confirmed Hereditary Angioedema (HAE) Attacks for Each Efficacy Evaluation Period [Time Frame: Day 0 through Day 364, Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Number of Participants with Characteristics of Investigator-Confirmed Hereditary Angioedema (HAE) Attacks for Each Efficacy Evaluation Period [Time Frame: Day 0 through Day 364, Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Number of Participants with Hereditary Angioedema (HAE) Attack-Free Status for Each Evaluation Period [Time Frame: Day 0 through Day 364, Day 0 through Day 182, Day 70 through Day 182, Day 183 through Day 364, Day 70 through Day 364]
Plasma Kallikrein (pKal) Activity [Time Frame: Day 0 (Pre-dose), Day 4, 14, 28, 56, 84, 112, 140, 168, 182 196, 252, 308, 364 and 392]
Number of Participants with Positive Immunogenicity [Time Frame: Day 0 (Pre-dose), Day 28, 84, 140, 182, 196, 252, 308, 364 and 392]