Hydrogen peroxide as a potential marker for monitoring airway inflammation in severe asthma patients on biologics

<bold>Introduction:</bold> Monitoring biologic treatment response in severe asthmatics requires objective biomarkers, given limitations in assessing optimal control based mainly on symptoms and lung function. In this respect, we investigated a potential marker of airway inflammation, hydrogen peroxide (H₂O₂), measured by exhaled breath condensate (EBC). <bold>Materials and Methods</bold>: In this monocenter, prospective study, we assessed exhaled H₂O₂ levels in severe asthmatics on biologics and healthy controls with Inflammacheck® by Exhalation Technology. H₂O₂ fluctuations in asthmatics were explored over two weeks. Symptoms were defined as high vs. low-controlled based on asthma control questionnaires ACT and ACQ6. Low-control was defined as ACT≤19 and/or ACQ6≥1 and high-control: ACT>19 and/or ACQ6<1. WhitneyU test (p≤0.05) was used to compare H₂O₂ of high-controlled severe asthmatics and healthy controls. <bold>Results:</bold> In 16 severe asthmatics, there were no significant exhaled-H₂O₂ differences at baseline and after two weeks. Low-controlled patients (n=5) had elevated H₂O₂ (median[IQR]: 0.96[0.8-1.4]μM) vs high-controlled (n=11; median[IQR]: 0.5[0.1-0.6]μM) (p=0.002). These latter, exhibited slightly higher H₂O₂ concentrations than healthy controls (n=16; median[IQR]: 0.4[0.1-0.6]) (p=0.05; p=0.01. Based on ACT, ACQ6, respectively). <bold>Conclusions:</bold> These preliminary findings suggest that H₂O₂ is associated with symptoms’ control in severe asthma patients on biologics, hinting at its potential as a stable, objective marker for severe asthma disease monitoring. Subsequent analyses will aim to confirm H₂O₂ utility in enhancing disease management for severe asthma patients on biologics.