Life‐threatening pneumonitis after first‐line treatment with osimertinib for primary T790M mutated non‐small cell lung cancer

Epithelial growth factor receptor (EGFR) directed tyrosine kinase inhibitor (TKI) treatment is the standard approach in patients with advanced, EGFR‐mutated non‐small cell lung cancer (NSCLC). Although benefit/risk ratio is favorable for these TKI and side effects are manageable in the vast majority of patients, severe and even life‐threatening side effects have been reported. TKI‐induced interstitial lung disease (ILD) has been reported for single cases in modest severity, predominantly in EGFR‐TKI pretreated patients. Here, we report a case of successful stabilization of a life‐threatening ILD in a de novo T790M mutated NSCLC during first‐line treatment with osimertinib. As osimertinib will be used more often in many EGFR‐positive NSCLC patients in the future, this potentially life‐threatening side effect should receive special attention, especially in first‐line treatment.