Temporal Heterogeneity of Resistance Mechanisms to EGFR-TKI Identified in a Patient With Lung Adenocarcinoma and Sarcomatoid Transformation

Sarcomatoid transformation is a relatively rare mechanism of epidermal growth factor receptor tyrosine kinase inhibitor resistance; however, the molecular features and survival outcomes after transformation remain largely unknown. We have reported the alternate occurrence of MET amplification and EGFR T790M mutation under drug selection pressure in a patient with gefitinib-treated lung adenocarcinoma with sarcomatoid transformation. The identification of these dynamic molecular resistance mechanisms allowed for successful application of targeted therapies, which prolonged the patient's survival time after transformation to 16 months. The present case suggests the presence of highly heterogeneous drug-driven molecular features after sarcomatoid transformation. In addition, targeted therapies might promote the survival outcomes for patients with sarcomatoid transformation. (C) 2020 The Author(s). Published by Elsevier Inc.