A Study of the Efficacy and Safety of Omalizumab (Xolair) in Patients With Chronic Idiopathic Urticaria (CIU)/Chronic Spontaneous Urticaria (CSU) Who Remain Symptomatic Despite Antihistamine (H1) Treatment

The study is a global Phase III, multicenter, randomized, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy and safety of omalizumab administered subcutaneously as an add-on therapy for the treatment of adolescent and adult patients aged 12-75 who have been diagnosed with refractory CIU and who remain symptomatic despite standard-dose H1 antihistamine treatment.

Type I Error Rate Control Plan

Primary Outcome Measure

In order to maintain an overall type I error rate of 0.05 (2-sided) across the 3 omalizumab dose levels, the testing of the primary Outcome Measure was conducted in the following hierarchical order. A p-value \< 0.05 is only considered statistically significant if statistical significance was claimed at the previous stage.

* Stage 1: Omalizumab 300-mg group vs. placebo
* Stage 2: Omalizumab 150-mg group vs. placebo
* Stage 3: Omalizumab 75-mg group vs. placebo

Secondary Outcome Measures

A hierarchical analysis of the following secondary Outcome Measures was performed for each dose found to be significant in the primary Outcome Measure. A p-value \< 0.05 is only considered statistically significant if statistical significance was claimed at the previous stage.

* Stage 1: Change from baseline to Week 12 in the urticaria activity score over 7 days (UAS7)
* Stage 2: Change from Baseline to Week 12 in the weekly number of hives score
* Stage 3: Time to minimally important difference (MID) response in the weekly itch severity score by Week 12
* Stage 4: Percentage of participants with a UAS7 score ≤ 6 at Week 12
* Stage 5: Percentage of weekly itch severity score MID responders at Week 12
* Stage 6: Change from Baseline to Week 12 in the weekly size of the largest hive score
* Stage 7: Change from Baseline in the overall dermatology life quality index (DLQI) score at Week 12
* Stage 8: Change from Baseline in the overall dermatology life quality index (DLQI) score at Week 12
* Stage 9: Percentage of complete responders (UAS7 = 0) at Week 12

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of Chronic Idiopathic Urticaria (CIU)/Chronic Spontaneous Urticaria (CSU) refractory to H1 antihistamines at the time of randomization.

Exclusion Criteria:

* Treatment with an investigational agent within 30 days prior to screening.
* Weight \< 20 kg (44 lbs).
* Clearly defined underlying etiology for chronic urticarias other than CIU.
* Evidence of parasitic infection.
* Atopic dermatitis, bullous pemphigoid, dermatitis herpetiformis, senile pruritus, or other skin disease associated with itch.
* Previous treatment with omalizumab within a year prior to screening.
* Routine doses of the following medications within 30 days prior to screening: Systemic or cutaneous (topical) corticosteroids (prescription or over the counter), hydroxychloroquine, methotrexate, cyclosporine, or cyclophosphamide.
* Intravenous (IV) immunoglobulin G (IVIG), or plasmapheresis within 30 days prior to screening.
* Regular (daily/every other day) doxepin (oral) use within 6 weeks prior to screening.
* Any H2 antihistamine use within 7 days prior to screening.
* Any leukotriene receptor antagonist (LTRA) (montelukast or zafirlukast) within 7 days prior to screening.
* Any H1 antihistamines at greater than approved doses within 3 days prior to screening.
* Patients with current malignancy, history of malignancy, or currently under work-up for suspected malignancy except non-melanoma skin cancer that has been treated or excised and is considered resolved.
* Hypersensitivity to omalizumab or any component of the formulation.
* History of anaphylactic shock.
* Presence of clinically significant cardiovascular, neurological, psychiatric, metabolic, or other pathological conditions that could interfere with the interpretation of the study results and or compromise the safety of the patients.
* Evidence of current drug or alcohol abuse.
* Nursing women or women of childbearing potential, unless they meet the following definition of post-menopausal: 12 months of natural amenorrhea or 6 months of spontaneous amenorrhea with serum follicle-stimulating hormone (FSH) levels \> 40 mIU/mL or 6 weeks post surgical bilateral oophorectomy (with or without hysterectomy) or hysterectomy or are using one or more of the following acceptable methods of contraception: surgical sterilization, hormonal contraception, and double-barrier methods.