ABSTRACT Idiopathic chronic eosinophilic pneumonia (ICEP) often relapses upon corticosteroid tapering. Biologics targeting interleukin‐5 (IL‐5) are effective, but optimal dosing intervals remain unclear. We report a case of relapsing ICEP in a patient in her 50s. Mepolizumab, an IL‐5 ligand blocker, failed to maintain remission, with clinical relapse occurring 4 months after initiation. Switching to benralizumab, an interleukin‐5 receptor blocker, induced rapid and deep eosinophil depletion. For optimising dosing, treatment was temporarily withheld, revealing a prolonged remission duration of 8 months before eosinophil recovery and clinical relapse. Based on these kinetics, a 6‐monthly benralizumab maintenance strategy was established. The patient has remained relapse‐free with zero eosinophils for over 2 years under this biannual regimen. This case suggests that benralizumab offers superior durability compared to mepolizumab in CEP due to deep depletion, enabling an extended, cost‐effective dosing interval guided by individual eosinophil recovery kinetics.
Sumi et al. (Sun,) studied this question.
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