Colocalization of Cancer Associated Biomarkers on Single Extracellular Vesicles for Early Cancer Detection

Abstract

Detection of cancer early, when it is most treatable, remains a significant challenge due to the lack of diagnostic methods sufficiently sensitive to detect nascent tumors. Early-stage tumors are small relative to their tissue of origin, heterogeneous, and infrequently manifest in clinical symptoms. Detection of their presence is made more difficult by a lack of abundant tumor-specific indicators (i.e., protein biomarkers, circulating tumor DNA, etc.) that would enable detection using a non-invasive diagnostic assay. In addition, many benign conditions manifest in a similar manner, thus discriminating an early-stage cancerous lesion from a benign tumor can present additional challenges and result in unnecessary medical procedures. To overcome these obstacles, we have developed a liquid biopsy assay that interrogates circulating extracellular vesicles (EVs) to detect tumor-specific biomarkers colocalized on the surface of individual EVs. Extracellular vesicles from all cell types, including early-stage tumors, are known to be abundant in blood, are remarkably stable, and serve as a biopsy of their cell of origin. The detection of a colocalized combination of cancer associated biomarkers that provide tumor specificity on the surface of extracellular vesicles enables the discrimination of early- and late-stage cancer from non-malignant conditions.