Real-world effects of asthma biologics on blood eosinophil levels: data from the CHRONICLE study

High blood eosinophil counts (BECs) are associated with increased asthma exacerbation risk. Studies show anti-IL-5/5R biologics meaningfully reduce BEC; however, there are limited data describing the real-world effects of anti-IgE and anti-IL-4R biologics on BECs. This analysis aimed to describe BECs before and after initiation of different biologics in a real-world cohort of patients with severe asthma (SA).

CHRONICLE (NCT03373045) was an observational study of subspecialist-treated adults with SA in the US receiving biologics or maintenance systemic corticosteroids or whose disease was persistently uncontrolled on high-dosage inhaled corticosteroids and additional controllers. This analysis included patients enrolled between February 2018 and November 2023 who initiated omalizumab, mepolizumab, benralizumab, or dupilumab treatment. Patients' highest BECs in the 12 months before, 2 to <12 months after, and ≥12 months after biologic initiation were evaluated.

In total, 323 of the 3912 enrolled patients met the inclusion criteria, of whom 61 received omalizumab, 80 received mepolizumab, 118 received benralizumab, and 64 received dupilumab. Patients treated with anti-IL-5/5R biologics (mepolizumab, benralizumab) had higher pretreatment BECs that were reduced at both 2 to <12 months and ≥12 months following initiation. Conversely, patients treated with anti-IL-4R (dupilumab) or anti-IgE (omalizumab) biologics had lower pretreatment BECs that were slightly reduced 2 to <12 months following initiation but increased ≥12 months following initiation.

Among US subspecialist-treated patients with SA, those treated with biologics that do not block or reduce IL-5/5R may experience an increase in BEC over time.