Role of Immunoglobulin E (IgE) Bearing Cells in Chronic Idiopathic Urticaria (CIU)

Inclusion Criteria

• Male or female, age >18 years old
• Females must be surgically sterile or postmenopausal or using a highly effective form of birth control throughout the duration of the study.
• Females must have a negative urine pregnancy test at screening and other visits specified in this protocol unless documented to have a hysterectomy or be postmenopausal.
• Clinical history of CIU at the time of screening, as defined by pruritus and hives for > 3 days in a 7-day period for > 6 consecutive weeks despite treatment with H1 antihistamine.
• CIU diagnosis > 3 months (by history)
• No underlying etiology clearly defined for urticaria (main manifestation cannot be physical urticaria).
• Non-diary based UAS scores ≥ 2 at either the screening visit (Week -3), at the run-in visit (Week -2), or on Day 1.
• Compliance with study procedures during run-in period (e.g., completion of the study diary).

Exclusion Criteria

• Pregnant females, Recent history of drug or alcohol abuse (within 3 years prior to screening visit).Inability or unwillingness of a participant to give written informed consent or comply with study protocol.
• Use of any investigational drugs within 30 days of screening.
• Active atopic dermatitis or other skin disease associated with pruritus during the time of the study, which require treatment with topical corticosteroids.
• Clinically relevant major systemic disease (making interpretation of the study results difficult) including a history of anaphylaxis.
• Inability to comply with study and follow-up procedures
• Patients may not use oral or systemic steroids during the study or within 4 weeks prior to enrollment.
• Patients may not take H2 antihistamines and leukotriene receptor antagonists within 7 days before screening, during the screening, run-in, or treatment phases. The exception will be if they are already on these medications for the treatment of Gastro-Esophageal Reflux Disease (GERD), asthma or allergic rhinitis.
• Any clinically relevant abnormal findings in clinical chemistry, hematology, urinalysis, physical examination, pulse, blood pressure at baseline, which, in the opinion of the investigator, could put the patient at risk because of his/her participation in the study.
• Past or current medical problems or findings from physical examination or laboratory testing that are not listed above, which, in the opinion of the investigator, may pose additional risks from participation in the study, may interfere with the participant's ability to comply with study requirements or may compromise the quality of the data obtained from the study.