Early detection of cancer using extracellular vesicle-based liquid biopsy enhanced by priming agents - Project Summary Cancer is one of the leading causes of death, attributed to nearly 10 million deaths per year worldwide, and its growing incidence represents a significant global health issue. Early detection of cancer is one of the most significant clinical interventions that improve clinical outcomes in patients with cancer. Blood biopsy-based tests are a promising frontier for detecting molecular-level information of cancers in a minimally invasive way. One common blood biopsy analyte is circulating tumor DNA (ctDNA), for which tests have been developed for detection of various DNA-level features. However, ctDNA-based tests are incapable of providing molecular information past DNA-level changes, such as changes in transcriptome, protein expression, or cell population, which are all often important for clinical decision making. Tumor-derived extracellular vesicles (tEVs) can carry a variety of biomarkers, including mRNA, and are potentially powerful liquid biopsy analytes to provide information on transcriptional and expression status of cancers. Yet tEVs, like other liquid biopsy analytes, face challenges of low abundance and tumor fraction, which limit their clinical use. To address this, our lab has recently shown that administration of nanoparticle “priming agents” can transiently delay clearance of ctDNA, increasing its abundance in circulation and the sensitivity of ctDNA-based diagnostic tests. The overarching goal of the proposed work is to test whether priming agents can increase recovery of tEVs from blood biopsy and thus improve the sensitivity of tests based on tEV-derived mRNA (tEV-mRNA) quantification. Aim 1 will develop novel priming agents targeting different EV markers involved in the uptake of EVs to delay their clearance. This will be accomplished through in-house formulation of priming agents, and studying the activity of these priming agents using in vitro models and in vivo models with exogenously delivered fluorescent EVs. Aim 2 will demonstrate that our novel priming agents can increase tumor-derived EV recovery from multiple in vivo cancer models. Aim 3 will characterize the effect of priming agents on quantification of clinically-relevant gene transcripts from tEV-mRNA. A custom digital droplet PCR assay will be established to quantify copy number of transcripts for key genes expressed in breast and prostate cancer. This work has the potential to realize novel paradigms for methods for early detection of cancer and to lay the groundwork for minimally invasive blood biopsy tests to detect and monitor cancer at the transcriptome level across a wide variety of cancer types.
