# Six‐Month Benralizumab Maintenance for Relapsing Chronic Eosinophilic Pneumonia Guided by Eosinophil Kinetics

## TL;DR

A patient with chronic eosinophilic pneumonia achieved long-term remission using a 6-month benralizumab regimen based on their body's response.

## Contribution

A personalized 6-month benralizumab dosing strategy is proposed for chronic eosinophilic pneumonia.

## Key findings

- Benralizumab induced deep and prolonged eosinophil depletion compared to mepolizumab.
- An 8-month remission was observed after treatment withdrawal, guiding a 6-month dosing interval.
- The patient remained relapse-free for over 2 years with the biannual regimen.

## 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.

We report a case of relapsing chronic eosinophilic pneumonia where benralizumab showed superior durability compared to mepolizumab. Based on the eosinophil recovery kinetics (relapse at 8 months after withdrawal), a personalised maintenance strategy of benralizumab every 6 months was established, successfully maintaining remission for over 2 years.