Characteristics of asthma patients responding to anti-IgE therapy

Introduction: Omalizumab is recommended in the treatment of patients with refractory asthma; response to this expensive therapy is not uniform. The characteristics associated with good treatment response are poorly defined. Objectives: Our goal was to determine what patient characteristics, other than atopy and IgE level, might predict response to therapy with omalizumab. Methods : We carried out a retrospective review of adult patients, followed at a tertiary asthma clinic, who received treatment with omalizumab for at least 6 months. The following data were collected: IgE level, atopy, sputum eosinophils and neutrophils, blood eosinophils, associated rhinosinusitis / nasal polyps. Response to therapy was judged by one asthma specialist and an asthma nurse clinician based on maintenance therapy required, exacerbations, FEV1 and ACQ score. Groups were compared using Chi-square and t-tests. Results: 17 patients were included; 12 were considered to have responded to omalizumab. Of 13 patients who provided induced sputum for inflammatory profile, 9 were classified as responders. All responders had elevated sputum eosinophils (> 2%) vs 25% of non-responders (p=0.014) but none had high neutrophils (>65%) vs all non-responders (p= 0.001). Elevated blood eosinophilia (> 0.5 x10^9/L) was present in 82% of responders while 80% of non-reponders had results within normal limits (p= 0.036). Conclusions: Sputum inflammatory profile and blood eosinophils predict response to omalizumab among atopic patients with refractory asthma.