Relationship between pretreatment specific IgE and the response to omalizumab therapy

Omalizumab, an anti-IgE antibody, has proven efficacy in patients with moderate-to-severe and severe persistent allergic (IgE-mediated) asthma. While previous analyses have had some limited success in predicting which patients will gain greatest benefit based on pretreatment baseline characteristics, it remains important to try to improve this predictability. Following a run-in phase, patients (12-75 years) inadequately controlled despite current therapy were randomized to receive omalizumab or placebo for 28 weeks in a double-blind, parallel-group, multicenter study (INNOVATE). Univariate analyses were performed to assess whether pretreatment specific IgE serum levels and related variables could be identified that were predictive of a response to omalizumab patients (n = 337) enrolled in INNOVATE. Response was measured via variables including exacerbations, QoL, FEV₁ and physicians' overall assessment. A total of 305 patients (90.5%) were sensitive to more than one allergen and the majority of patients were positive to D1 Dermatophagoides pteronyssinus and D2 Dermatophagoides farinae. Patients with relatively high values of D1 or D2, but with these making a relatively low contribution to total specific IgE load, appeared to attain most benefit from omalizumab. However, no consistent predictive effect for omalizumab response was observed either for total specific IgE or levels of IgEs specific for individual allergens. Based on these data, pretreatment allergen-specific IgE levels do not provide any better prediction of response to treatment as compared with pretreatment total IgE. At present, the most reliable method of identifying patients who respond to omalizumab treatment remains a physician's assessment.