Correlation Between IgE Parameters and the Response to Omalizumab in Subjects With Severe Asthma

Omalizumab is an anti-IgE recombinant humanized monoclonal antibody.The efficacy and tolerability of omalizumab have been demonstrated in patients with moderate-to-severe and allergic (IgE-mediated) asthma. Clinical benefit with omalizumab is observed when serum free IgE levels are reduced to 50 ng/mL or less. However, although the causal role of IgE in allergic disease is well established, the relationship between free IgE and clinical symptoms of asthma has not been accurately quantified. Recent study demonstrated that omalizumab and free IgE concentrations are correlated with clinical outcomes. In non responder to omalizumab the clinical symptoms show random fluctuations around baseline without any tendency toward improvement despite adequate suppression of free IgE. In these patients it may be the ratio of specific IgE to total IgE or inter-patient variability in the expression of FceRI on effector cells that define whether the patient will respond or not to omalizumab. This current study is designed to evaluate the mechanisms of responsiveness to omalizumab measuring the free IgE, specific IgE and the level of FceRI expression on the effector cell and the correlation to clinical response.