Osimertinib-induced severe bilateral pneumothorax: A case report

Rationale: Osimertinib is the third-generation, pyrimidine-based, irreversible epidermal growth factor receptor-tyrosine kinase inhibitor that received approval from the FDA in November 2015 and has become the standard approach in patients with advanced, epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC), especially with brain metastases. Osimertinib is beneficial in terms of progression-free and overall survival in patients with EGFR-mutated NSCLC. However, the rarity of bilateral pneumothorax among adverse events necessitates further research on its potential fatality rate. Patient concerns: A 72-year-old man diagnosed with stage IV (T2NxM1) NSCLC with the 21L858R mutation of the EGFR gene received osimertinib treatment. Unfortunately, 10 weeks after osimertinib treatment, the patient developed severe interstitial lung disease and pneumothorax. Thus, osimertinib treatment was discontinued, and prednisolone (160 mg/day) and supportive treatment were administered. Diagnoses: Osimertinib-induced severe interstitial lung disease and pneumothorax. Interventions: Osimertinib treatment was discontinued, and prednisolone (160 mg/day) and supportive treatment were administered. Outcomes: The bilateral pneumothorax was difficult to correct and the patient eventually died. Lessons: Osimertinib-induced pneumothorax occurred approximately 10 weeks after receiving the drug and had severe cough and chest tightness as initial symptoms. In addition, the incidence of drug-induced pneumothorax increases in patients treated with osimertinib when combined with underlying respiratory diseases.