Omalizumab Effectiveness by Biomarker Status in Patients with Asthma: Evidence From PROSPERO, A Prospective Real-World Study. Casale Thomas B,Luskin Allan T,Busse William,Zeiger Robert S,Trzaskoma Benjamin,Yang Ming,Griffin Noelle M,Chipps Bradley E The journal of allergy and clinical immunology. In practice BACKGROUND:Omalizumab has demonstrated efficacy in clinical trials of patients with asthma, but real-world data are needed. OBJECTIVE:To assess outcomes after omalizumab initiation in patients with asthma in a real-world setting. METHODS:Patients aged 12 years and older with allergic asthma who were candidates for omalizumab on the basis of physician-assessed need were enrolled in a US-based, prospective, single-arm, 48-week multicenter study, the Prospective Observational Study to Evaluate Predictors of Clinical Effectiveness in Response to Omalizumab. Monthly assessments included exacerbations, health care utilization, asthma control test (ACT), and adverse events. At baseline, 6 months, and end of study, biomarkers (blood eosinophils and fractional exhaled nitric oxide) were collected and spirometry performed. RESULTS:Of 806 enrollees, 801 (99.4%) received omalizumab and 622 (77.2%) completed the study. The exacerbation rate significantly improved from a mean of 3.00 ± 3.28 in the 12 months before baseline to 0.78 ± 1.37 through month 12 (P < .001) and was similar in adults and adolescents; there was a reduction of 81.9% in the percentage of patients with 1 or more hospitalizations. Lung function remained generally unchanged. A mean improvement of 4.4 ± 4.9 in ACT scores was observed. Eighty-seven percent of patients were responders on the basis of clinical improvement in exacerbations, lung function, or ACT scores. Baseline biomarker status was associated with ACT scores and lung function improvement, but the magnitude of this improvement was not clinically relevant. No new safety signals emerged. CONCLUSIONS:Omalizumab initiation in patients with asthma resulted in improved exacerbation rates, reduced hospitalizations, and improved ACT scores compared with pretreatment values, regardless of biomarker status. 10.1016/j.jaip.2018.04.043