A Phase III Study of and Efficacy of Ligelizumab in the Treatment of CSU in Adolescents and Adults Inadequately Controlled With H1-antihistamines.

Key Inclusion Criteria:

• Signed informed consent must be obtained prior to participation in the study. Thesubject's, parent's or legal guardian's signed written informed consent and child'sassent, if appropriate, must be obtained before any assessment is performed. Ofnote, if the subject reaches age of consent (age as per local law) during the study,they will also need to sign the corresponding study Informed Consent Form (ICF) atthe next study visit.

• Male and female subjects ≥ 12 years of age at the time of screening.

• CSU diagnosis for ≥ 6 months.

• Diagnosis of CSU refractory to H1-AH at approved doses at the time of randomization,as defined by all of the following:

• The presence of itch and hives for ≥ 6 consecutive weeks at any time prior to Visit 1 (Day - 28 to Day -14) despite current use of non-sedating H1-antihistamine

• UAS7 score (range 0-42) ≥ 16 and HSS7 (range 0-21) ≥ 8 during the 7 days prior torandomization (Visit 110, Day 1)

• Subjects must be on H1-antihistamine at only locally label approved doses fortreatment of CSU starting at Visit 1 (Day -28 to Day -14)

• Willing and able to complete a daily symptom eDiary for the duration of the studyand adhere to the study visit schedules.

Key Exclusion Criteria:

• History of hypersensitivity to any of the study drugs or their excipients or todrugs of similar chemical classes (i.e. to murine, chimeric or human antibodies).

• Subjects having a clearly defined cause of their chronic urticaria, other than CSU.This includes, but is not limited to, the following: symptomatic dermographism (urticaria factitia), cold-, heat-, solar-, pressure-, delayed pressure-,aquagenic-, cholinergic- or contact-urticaria.

• Diseases, other than chronic urticaria, with urticarial or angioedema symptoms suchas urticarial vasculitis, erythema multiforme, cutaneous mastocytosis (urticariapigmentosa) and hereditary or acquired angioedema (eg, due to C1 inhibitordeficiency).

• Subjects with evidence of helminthic parasitic infection as evidenced by stoolsbeing positive for a pathogenic organism according to local guidelines. All subjectswill be screened at Visit 1. If stool testing is positive for pathogenic organism,the subject will not be randomized and will not be allowed to rescreen.

• Any other skin disease associated with chronic itching that might influence in theinvestigators opinion the study evaluations and results (e.g. atopic dermatitis,bullous pemphigoid, dermatitis herpetiformis, senile pruritus, etc.).

• Prior exposure to ligelizumab or omalizumab.

• H1-AH used as background medication at greater than locally label-approved dosesafter visit 1