A Study of the Efficacy and Safety of Omalizumab Through 48 Weeks in Participants With Chronic Idiopathic Urticaria

XTEND-CIU (Xolair Treatment Efficacy of Longer Duration in Chronic Idiopathic Urticaria): A Phase IV, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Omalizumab Through 48 Weeks in Patients With Chronic Idiopathic Urticaria

This multicenter, randomized, double-blind, placebo-controlled study will evaluate the efficacy and safety of subcutaneous (SC) omalizumab (Xolair) as an add-on therapy through 48 weeks for treatment of H1 antihistamine refractory chronic idiopathic urticaria (CIU). After completing an initial 24-week open-label treatment period with omalizumab 300 milligrams (mg) every 4 weeks (Q4W), participants responding to omalizumab will be randomized at a 3:2 ratio (omalizumab:placebo) to either continue omalizumab or be transitioned to placebo for a further 24 weeks.

Inclusion Criteria:

• Diagnosis of CIU refractory to H1 antihistamines at baseline
• Presence of itch and hives for at least 8 consecutive weeks at any time prior to enrollment despite current use of H1 antihistamine treatment (up to four times the approved dose) during this time period
• UAS7 score (range 0-42) ≥ 16 and itch component of UAS7 (range 0-21) ≥ 8 during 7 days prior to baseline
• Participants must have been on a non-sedating H1 antihistamine treatment (up to four times the approved dose) for CIU for at least 3 consecutive days immediately prior to screening visit with continued current use on the day of the initial screening visit
• CIU diagnosis for ≥ 6 months
• Willing and able to complete a daily symptom eDiary for the duration of the study

Exclusion Criteria:

• Treatment with an investigational agent within 30 days of the initial screening visit
• Body weight less than 20 kilograms
• Clearly defined underlying etiology for chronic urticarias other than CIU
• Evidence of a parasitic infection
• Atopic dermatitis, bullous pemphigoid, dermatitis herpetiformis, senile pruritus or other skin disease associated with itch
• Previous treatment with omalizumab within 1 year prior to the initial screening visit
• Participants may not have taken during treatment period or have been taking within 30 days before the initial screening visit any of the following medications or treatments:

regular (daily/every other day during 5 or more consecutive days) systemic corticosteroids, hydroxychloroquine, methotrexate, mycophenolate, cyclosporine, cyclophosphamide, intravenous immunoglobulin G or plasmapheresis

• Regular (daily/every other day) oral doxepin use within 14 days prior to the initial screening visit
• Pregnant or lactating women, or women intending to become pregnant during the study