Noninvasive Diagnosis and Molecular Phenotyping of Breast Cancer through Microbead‐Assisted Flow Cytometry Detection of Tumor‐Derived Extracellular Vesicles

Abstract Blood‐based detection and molecular phenotyping are highly desired for the early diagnosis and dynamic monitoring of cancer. Extracellular vesicles (EVs) carry molecular information from the cells of origin and are biomarkers of cancer. However, the detection and molecular analysis of EVs has been challenging due to their nanoscaled size. Here, an assessment of the detection and molecular phenotyping of serum EVs based on microbead‐assisted flow cytometry is established. The clinical utility of this method is validated in the diagnosis and human epidermal growth factor receptor 2 (HER2) phenotyping of breast cancer. Good correlation between the status of epithelial cell adhesion molecule (EpCAM) and HER2 expression in EVs and in the cells of origin is found. Both EpCAM+ and HER2+ EVs are demonstrated to be effective diagnostic markers of breast cancer with high sensitivity and specificity. EV‐based HER2 phenotyping is consistent with tissue‐based HER2 phenotyping by immunohistochemistry and can be used as a surrogate for the invasive tissue assessments. The microbead‐assisted flow cytometry assessment of EVs enables rapid and noninvasive detection and molecular phenotyping of cancer and would help to personalized treatment and cancer survival.