Measured Immunoglobulin E in Allergic Bronchopulmonary Aspergillosis Treated With Omalizumab

Background. The ability to assess adequate reductions in immunoglobulin E (IgE) in allergic bronchopulmonary aspergillosis (ABPA) has been a concern with regards to omalizumab treatment. Objective. To describe the clinical course and serial measured IgE levels in two adult patients with elevated IgE levels, hypersensitivity to Aspergillus fumigatus, and bilateral bronchiectasis who were treated with omalizumab. Clinical Descriptions. Patient 1 met commonly used critieria for ABPA and had a more than 3-fold increase (from 702 to 2462 IU/ml) in measured IgE 4 months after starting omalizumab. Two years after starting omalizumab, the IgE level decreased to baseline (473 IU/ml) even when corticosteroids were discontinued. Patient 2 had near normalization of elevated IgE levels when treated with corticosteroids but IgE levels subsequently rose again to over 10,000 IU/ml. After reducing the IgE level to 586 IU/ml with higher corticosteroid doses, omalizumab was initiated. Twenty months after starting omalizumab, the measured IgE was 510 IU/ml. Based on published omalizumab treatment-associated total/free IgE ratios, the estimated free IgE levels for both patients after more than a year of omalizumab treatment was less than their pre-omalizumab treatment IgE levels. Conclusions. These data suggest that omalizumab can be beneficial in treating ABPA and that measured IgE levels can still be useful in this context. Noting the pattern of IgE levels associated with ABPA exacerbations and with corticosteroid treatment may help both with achieving an IgE level appropriate for omalizumab treatment and with the interpretation of measured IgE changes associated with omalizumab treatment.