# Tezepelumab After Mepolizumab in Allergic Bronchopulmonary Mycosis: A Case Report

## TL;DR

A patient with allergic bronchopulmonary mycosis and asthma improved after switching from mepolizumab to tezepelumab, suggesting TSLP inhibition may help when IL-5 blockade is insufficient.

## Contribution

This case report suggests that tezepelumab may be effective in allergic bronchopulmonary mycosis when mepolizumab fails.

## Key findings

- The patient showed sustained improvement with tezepelumab, including reduced FeNO and IgE levels.
- Tezepelumab led to radiologic improvement in mucus plugs and atelectasis.
- Residual type 2 activity may persist despite IL-5 blockade, and TSLP inhibition could address this.

## Abstract

We describe the case of a 43-year-old woman with allergic bronchopulmonary mycosis (ABPM) and severe asthma who improved clinically on mepolizumab with eosinophil suppression but had recurrent mucus plugs, persistent right-middle-lobe atelectasis, rising fractional exhaled nitric oxide (FeNO), and high total IgE levels. Following a switch to tezepelumab, she attained sustained symptom control, no systemic steroid-requiring exacerbations, substantial FeNO and IgE decline, and radiologic reduction of mucus plugs and atelectasis. This case illustrates that residual upstream type 2 activity can persist despite IL-5 blockade, and thymic stromal lymphopoietin (TSLP) inhibition may address this gap by concurrently attenuating multiple effectors. In mucus-predominant allergic bronchopulmonary aspergillosis/ABPM with high FeNO/IgE levels after anti-IL-5 therapy, phenotype- and biomarker-guided sequencing of anti-TSLP antibodies may be considered.