Biomarkers Associated with Response in Patients Initiating Omalizumab: Baseline Levels Among Patients in the Prospective Observational Study to Evaluate Predictors of Clinical Effectiveness in Response to Omalizumab (PROSPERO) Study

Chipps, Bradley

Rationale: Biomarkers of type 2 inflammation in patients with allergic asthma include fractional exhaled nitric oxide (FeNO), peripheral blood eosinophils (EOS), and serum periostin (PERI). Biomarker relationships were explored using baseline data from an ongoing 48-week study of omalizumab clinical effectiveness.

Methods: Baseline values in adult patients (N=737) with allergic asthma who subsequently initiated treatment with omalizumab and had not received omalizumab within the preceding year were analyzed. Spearman correlation coefficients (r_s) of biomarkers between one another and with FEV₁ were determined.

Results: Mean baseline FEV₁ was 74.7% of predicted value, n=728. Median and geometric mean baseline biomarker values were: FeNO, 22.0 and 23.6 ppb, n=722; EOS, 230 and 220/μL, n=662; and PERI, 48.3 and 48.9 ng/mL, n=660. Biomarkers were weakly correlated with one another at baseline. FeNO correlations were: EOS, r_s=0.35 (95% CI 0.28, 0.41; p<0.0001; n=650); and PERI, r_s=0.27 (95% CI 0.20, 0.34; p<0.0001; n=648). Correlation between EOS and PERI was r_s=0.24 (95% CI 0.17, 0.31; p<0.0001; n=636). FEV₁was very weakly correlated with FeNO,r_s=−0.10 (95% CI −0.17, −0.03; p=0.0079; n=716); EOS, r_s=−0.12 (95% CI −0.19, −0.04; p=0.0028; n=659); and PERI, r_s=−0.08 (95% CI −0.16, −0.01; p=0.0360, n=657).

Conclusions: This analysis provides information on the biomarker characteristics of allergic asthma patients before they initiated treatment with omalizumab in a real world setting. It also highlights the heterogeneity of biomarker profiles and the potential value of assessing more than a single biomarker of type 2 asthma status.