P240 Low ige and not blood eosinophils predicts lack of response to omalizumab in uhsm cohort

Background Omalizumab is an anti-IgE monoclonal antibody therapy used in patients with inadequately controlled persistent allergic IgE mediated asthma who require continuous or frequent treatment with oral corticosteroids. Previous studies have tried to predict a patient’s response to omalizumab based on pre-treatment baseline characteristics. Most recent data has suggested that baseline blood eosinophils, serum periostin or FeNO may be predictive of response to omalizumab in the T H 2 phenotype. Aims This study will attempt to identify a characteristic that may explain why some patients suffering with severe asthma in a single severe asthma centre do not achieve a response when treated with the anti-IgE monoclonal antibody, omalizumab. Methods The target population was represented by all patients previously treated or undergoing treatment with omalizumab at the Severe Asthma Service at University Hospital South Manchester (n = 185). The study population was those for whom records could be found within the study period (n = 154). Demographic and clinical data was collected retrospectively from patient medical records. Results 16.2% of patients at UHSM did not show response to omalizumab at 16 weeks. Baseline serum IgE levels in the non-response group were on average 77.28 kU/L lower than those in the response group, statistical analysis of the two groups show that this difference was significant ( P = 0.04 ). Mean eosinophils in the true non-responder group were actually higher than those in the true responder group, however this difference was not statistically significant. No other demographic or disease specific measures predicted a lack of response to omalizumab. Discussion The results from the study indicate that a lower baseline serum IgE may predict non-response to treatment with omalizumab. The results also show that non-response rates at the NWLC were lower than those demonstrated in clinical trials (INNOVATE), were consistent with other real life studies (PERSIST/APEX I and APEX II) but markedly lower than those quoted in the eXpeRience registry.