Profiling blood hypereosinophilia in patients on dupilumab treatment for respiratory conditions: a real-life snapshot

Background: Transient and usually asymptomatic increase in blood eosinophil count (BEC) associated with dupilumab treatment has been described. Predicting factors related to BEC increase and symptoms occurrence are still poorly investigated. Objective: To investigate frequency, timing, duration, clinical relevance and potential predictors of BEC increase in a real-life multicentre cohort of patients affected by asthma and/or chronic rhinosinusitis with nasal polyps (CRSwNP) treated with dupilumab. Methods: BEC and clinical conditions at baseline and every 3 months after dupilumab treatment start were assessed. Any adverse drug reaction was also recorded. Remission of dupilumab-associated eosinophilia was defined by follow-up BEC values < 0.5 x10ˆ9 cells/L. Results: Overall, 108 out of 195 (55%) patients experienced an increased BEC after dupilumab initiation but only 29 out of 195 (14.9%) showed hypereosinophilia. BEC peak occurred 6 months after the treatment start and resolved after 9 months (median time). Probability of developing hypereosinophilia was 3.3 times higher in patients with baseline BEC between 0.5 and 1.5 cells x 109L. Symptoms occurrence during BEC peak was higher in patients with comorbidities and in patients showing any increase of BEC. Conclusions: In a real-life setting dupilumab treatment in asthma and/or CRSwNP patients was often associated with transient BEC increase but hypereosinophilia rarely occurred. Onset of symptoms co-occurring with BEC peak was observed in a minority of subjects. BEC should not preclude itself dupilumab initiation or continuation but deserves to be monitored for at least 8 months after the treatment start, particularly in the case of baseline eosinophilia/hypereosinophilia and/or comorbidities.