Non‐invasive analysis of tumor mutation profiles and druggable mutations by sequencing of cell free DNA of Chinese metastatic breast cancer patients

BACKGROUND: Metastatic breast cancer (MBC) remains an incurable disease worldwide. Tumor gene mutations have evolved and led to drug resistance in the treatment course of MBC. However, data on the mutation profiles and druggable genomic alterations of MBC remain limited, particularly among Chinese patients. Our study aimed to depict the mutation profiles and identify druggable mutations in circulating tumor DNA (ctDNA) in Chinese MBC patients. METHODS: Targeted deep sequencing of a 1021‐gene panel was performed on 17 blood samples and 5 available tissue samples from 17 Chinese MBC patients. RESULTS: We identified 60 somatic mutations in 17 blood samples (sensitivity 100%). Somatic mutations were identified in the blood samples of all patients, and 41.18% (7/17) of patients harbored at least one druggable mutation. A high ctDNA level in plasma is associated with shorter progression‐free survival. CONCLUSION: Targeted deep sequencing of cell free DNA is a highly sensitive, noninvasive method to depict tumor mutation profiles, identify druggable mutations in MBC, and predict patient outcome. Our study shed light on the utility of ctDNA as noninvasive “liquid biopsy” in the management of MBC.