Dupilumab-Related Hypereosinophilia in Patients Treated for Type 2 Diseases: Evidence from a 24-Month Prospective Real-Life Study

Background/Objectives: Dupilumab is a human monoclonal antibody that targets both IL-4 and IL-13 signaling. Eosinophilia has been reported as a potential adverse event in treated patients in randomized controlled trials and 12-month real-life studies. This real-life, 24-month prospective study investigated the prevalence of eosinophilia, its consequences, and the effectiveness of dupilumab in a cohort of patients with severe asthma, chronic rhinosinusitis with nasal polyps, and atopic dermatitis. Methods: A total of 66 adult patients treated with dupilumab were included in this study. ACT, SNOT-22, and Smell-VAS, EASI, and absolute blood eosinophil count (AEC) were assessed according to the type of diagnosis at baseline (T0), after 6 (T6), 12 (T12), 18 (T18), and 24 (T24) months post-dupilumab initiation. Results: All patients experienced significant improvement in both symptoms and disease control following dupilumab treatment. A total of 27 out of 66 (40.9%) patients developed eosinophilia within six months of treatment (AEC T6 mean ± SD 0.67 ± 0.68 109/L). Eosinophilia was generally mild and lasted on average for six months (AEC T12 mean ± SD 0.66 ± 0.65 109/L) with AEC normalization after 18 months of treatment (AEC T18 mean ± SD 0.58 ± 0.48 109/L). Ten patients (15.15%) developed hypereosinophilia, but no symptoms or signs of eosinophilic-related organ damage have been observed, with no need for dupilumab discontinuation. Conclusions: Dupilumab-related eosinophilia was common, generally mild, and transient, whereas persistent hypereosinophilia occurred in a small group of patients in the absence of symptoms or signs of eosinophilic damage.