A Study Evaluating the Persistency of Response With or Without Xolair After Long-Term Therapy (XPORT)

Inclusion Criteria:

• All EXCELS inclusion criteria and enrollment in the EXCELS study
• History of positive skin test or in vitro reactivity to an aeroallergen
• Continuous Xolair exposure from the beginning of EXCELS to randomization into this study. For the purposes of this study, continuous Xolair exposure is defined as having missed no more than 25% of scheduled Xolair doses. In addition, a maximum of 2 doses can be missed within the last 6 months before being randomized into this study
• Having completed EXCELS and not having discontinued Xolair since the completion of EXCELS
• Diagnosis of moderate to severe persistent allergic asthma while on Xolair
• Stable dosing of current asthma therapies, in addition to Xolair, over 2 months prior to enrollment
• Serum IgE level >= 30 to <= 700 IU/mL before initiation of Xolair treatment (prior to EXCELS enrollment or earlier)
• Body weight >= 30 to <= 150 kg
• Treatment with Xolair consistent with the USPI (based on the dosing table, recommended dose, administration, and dosing interval) at the time of completion of EXCELS study and prior to enrollment to this study

Exclusion Criteria:

• Participation in other therapy trials or planned participation during the following year from screening
• Contraindication to Xolair therapy
• Acute asthma exacerbation within the 2 months immediately prior to screening
• Any significant, or unstable, systemic disease, or a recent hospitalization because of systemic disease within the previous 2 months
• Diagnosis of active lung disease other than asthma
• Having more than 10 pack-years smoking history
• Diagnosis of cystic fibrosis
• Use of an experimental drug within 30 days prior to study screening
• Have elevated serum IgE levels for reasons other than allergy
• Pregnancy, lactation or any planned pregnancy in the following year