Circulating tumor extracellular vesicles to monitor metastatic prostate cancer genomic and transcriptomic evolution

Extracellular vesicles (EVs) secreted by tumors are abundant in plasma, but their potential for multi-omic profiling remains widely unexplored. Here, we pursued next-generation sequencing of circulating EV-DNA and EV-RNA in metastatic prostate cancer (mPC), using a range of in-vitro and in-vivo models, validating our findings in 35 mPC patients with longitudinal samples collected during androgen receptor signaling inhibitor (ARSI) therapy. EV-DNA copy-number (CN) profiles matched same-patient biopsies and ctDNA (p<0.001) and EV-DNA tumor fraction (TF) associated with shorter time to progression. We developed a novel approach for studying mRNA in circulating EVs (RExCuE), showing high correlation between EV-RNA and tumor biopsies (r>0.7, p<0.001). EV-RNAseq signatures at 4 weeks of therapy associated with clinical responses. Last, we derived a specific signature of ARSI response in EV-RNA in vivo that predicted response to therapy. In conclusion, EV profiling enables the study of mPC evolution at transcriptomics level in liquid biopsies.