Tumor Heterogeneity and Drug Resistance Mutations Using ctDNA in Metastatic EGFR Mutation-Positive Lung Adenocarcinoma: A Case Report

For advanced non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations, EGFR tyrosine kinase inhibitors (TKIs) have been approved as the standard therapy and shown clinical benefits. However, the emergence of drug resistance is inevitable. Tumor heterogeneity was often observed by imaging method to evaluate the progression of primary and metastatic lesions. Tissue biopsy was also unlikely to accurately capture the complete genomic landscape from a single tissue sample. Recently, genomic characterization of circulating tumor DNA (ctDNA) offer an opportunity to reveal the clonal dynamics throughout the course of a patient’s illness and provide comprehensive genomic landscape of tumors to assess tumor heterogeneity. Here, we reported a lung adenocarcinoma (LADC) with EGFR mutations who was treated with sequential EGFR TKIs. The CT image of the patient’s different lesions suggested that dynamic change of tumor heterogeneity had occurred. Targeted next-generation sequencing (NGS) analysis of ctDNA revealed dynamic changes of mutational profiles between the primary and metastatic tumors to discover tumor evolution to guide treatment decision-making.