A Study of Lanadelumab in Teenagers and Adults to Prevent Acute Attacks of Non-histaminergic Angioedema With Normal C1-Inhibitor (C1-INH)

Inclusion Criteria

The Participant will not be considered eligible for the study without meeting all of the applicable population criteria below.

• Males and females, 12 years of age and older for participants with non-histaminergic normal C1-INH angioedema at the time of signing of the informed consent form (ICF).
• Documented clinical history of recurrent attacks of angioedema in the absence of wheals/urticaria.
• Investigator-confirmed diagnosis of non-histaminergic bradykinin-mediated angioedema with normal C1-INH as documented by a history of angioedema attack(s) at screening and occurrence of attacks during the observation period:
• History of recurrent angioedema with at least an average of 1 angioedema attack per 4 weeks prior to screening and this attack rate must be confirmed during the observation period while treated with chronic high-dose antihistamine (cetirizine 40 milligram per day [mg/day] or equivalent high-dose second-generation antihistamine medication).
• Diagnostic testing results obtained during screening from a sponsor-approved central laboratory that confirm C1-INH function >= 50 percent (%) of normal and C4 level not below the normal range. With prior sponsor approval, participants may be retested during the observation period if results are incongruent with clinical history.
• Clinical history of not responding to high-dose antihistamine treatment (cetirizine 40 mg/day or equivalent high-dose second-generation antihistamine medication), which must be confirmed during the observation period with at least 1 angioedema attack per 4 weeks with chronic high-dose antihistamine treatment and no significant difference (as assessed by the investigator and in consultation with the sponsor's medical monitor, as necessary) from the historic attack rate without high-dose antihistamine treatment.
• Agree to adhere to the protocol-defined schedule of treatments, assessments, and procedures.
• Participants >= 18 years of age must be willing to use icatibant as the rescue medication during the observation and treatment period. During the observation period, participants need to be treated with icatibant for at least 2 angioedema attacks or at least 1 moderate or severe attack. In the opinion of the investigator, participants with no response to icatibant for acute angioedema attacks in the past medical history/screening, or no improvement or worsened attack severity 2 hours after icatibant treatment during the observation period (based on totality of assessments), will not be included. Note: For participants 12 to ) 38°C (100.4°F), tympanic > 38.5°C (101.3°F), axillary > 38°C (100.4°F), or rectal/core > 38.5°C (101.3°F) within 24 hours prior to the first dose of study drug in the treatment period.
• Any of the following liver function test abnormalities: alanine aminotransferase (ALT) > 3x upper limit of normal, or aspartate aminotransferase (AST) > 3x upper limit of normal, or total bilirubin > 2x upper limit of normal (unless the bilirubin elevation is a result of Gilbert's syndrome).
• Pregnancy or breast feeding.
• Participant has a known hypersensitivity to the investigational product or its components.
• Have any uncontrolled underlying medical condition which would require treatment adjustment during the study treatment period that, in the opinion of the investigator or sponsor, may confound the results of the safety assessments or may place the participant at risk. Participants with stable treatment for at least 3 months prior to screening and NOT expecting any change to their treatment regimen for 6 months during the study treatment period, will not be excluded.
• Have any condition (surgical or medical) that, in the opinion of the investigator or sponsor, may compromise their safety or compliance, preclude the successful conduct of the study, or interfere with interpretation of the results (e.g. significant pre-existing illness or other major comorbidities that the investigator considers may confound th