D1.95 - Dupilumab-induced eosinophilia: a transient effect

The increase in blood eosinophil count >500 cells/µL is a known reported adverse effect of dupilumab, a fully human monoclonal antibody targeting interleukin-4 receptor. Hypereosinophilia >1500 cells/µL is estimated in 2% of patients. We aim to evaluate induced-eosinophilia in patients with T2 severe asthma and/or chronic rhinosinusitis with nasal polyps (CRSwNP) treated with dupilumab.

Retrospective study including patients with asthma and/or CRSwNP treated with dupilumab, followed in our SAMU (2022-2024). Laboratory evaluation (blood eosinophil count, total serum IgE) was performed before dupilumab, and at 4, 8 and 12 months. Demographic and clinical data were collected from clinical files. For patients with eosinophils >500 cells/µL after dupilumab, an extensive evaluation was performed. Informed consent was obtained from all patients. Statistical analysis IBM SPSS 25®.

We included 15 patients, 4 (26.7%) of whom with dupilumab-related eosinophilia and 3 (20%) with hypereosinophilia. These last patients had documented baseline eosinophilia. The majority were female (n=9, 60%), mean age of 56.6+3.0 [32-82] years. The majority (n=12, 80%) had asthma and CRSwNP. In 7 patients (46.7%) dupilumab was a therapeutic switch (7 omalizumab, 1 mepoluzimab). Treatment was started at mean age of 52.7+13.1 [26-68] years, with mean duration of 19.1+3 [12-32] months - table I. In patients with dupilumab-related eosinophilia, mean blood eosinophil count at T0 was 780+100 [420-1270] cells/µL. A significant increase was observed at T4, mean value of 1706.7+60 [850-2880] cells/µL. At T12 a decrease was observed, mean value of 1036+275 [300-2340] cells/µL, not statistically significant. All patients remained asymptomatic, regardless of eosinophil count, with normal complementary evaluation, maintaining biological treatment – table II. Before dupilumab, 9 (60%) patients were steroid dependent, mean dosage of prednisolone of 11,1mg/day. At T12, only 3 remained under steroids, mean dosage of 5mg/day. 

Our results suggest that dupilumab-induced eosinophilia is a common adverse effect. However, all patients remained asymptomatic regardless of eosinophil count, without eosinophil-related organ involvement. A sustained decrease in blood eosinophil count was observed at 12 months, enhancing the temporary profile of this adverse effect, as previously suggested in the literature. A close follow-up is mandatory in these patients, in order to safely maintain dupilumab treatment.