Complications of switching from anti–IL-5 or anti–IL-5R to dupilumab in corticosteroid-dependent severe asthma

[...]on rare occasions, anti–IL-4/13 biologics such as dupilumab may induce hypereosinophilia, with sudden deterioration of asthma, tissue infiltration by eosinophils, and EGPA-like symptoms such as thromboembolic events. [...]our current strategy is to stop dupilumab and (re)start anti–IL-5 therapy if eosinophils rise to more than 1000 cells/L and asthma symptoms worsen. [...]eosinophilic complications may occur after switching from an anti–IL-5 to an anti–IL-4/13 monoclonal despite an initial favorable response. Outcome Patient 1 Patient 2 Patient 3 Patient 4 Age (y) 59 35 48 63 Sex (F/M) F M F F Before anti–IL-5 treatment Asthma exacerbations (n/y) “Frequent” >10 “Frequent” “Frequent” ACQ score >4 >4 >2 >3 Prednisolone (mg/d) 15 40 40 32.5 FEV1 (% predicted) 58% 38% 54% 68% Blood eosinophils (cells/μL)∗ 1190 1670 2200 760 Feno (ppb)∗ 159 >300 221 NA Total IgE (IU/L) 1663 753 366 96 Specific IgE to aspergillus (IU/L)