Evaluation of two commercial omalizumab/free IgE immunoassays: implications of use during therapy

AbstractBackground:The anti-IgE monoclonal antibody, omalizumab, is approved in the US as add-on therapy for patients ≥12 years of age with moderate-to-severe persistent allergic asthma. Omalizumab is administered according to the US Food and Drug Administration approved dosing table included in the prescribing information. The dosing table was developed using Genentech’s free IgE assay and is designed to achieve free serum IgE levels of <50 ng/mL, known to be associated with clinical benefit. Lack of clinical benefit in a subset of patients on omalizumab has prompted demand for commercial free IgE assays to guide omalizumab dosing. To date, two commercial free IgE assays marketed by ViraCor-IBT (no longer offered) and BioTeZ have been available to physicians.Objective:This study compares the results generated from the two commercial free IgE assays with the free IgE levels generated by the Genentech assay.Methods:Two serum sample sets were prepared using 20 samples from patients with a wide range of IgE ...