Development of biofluid-based molecular diagnostic tests for
cancer is an important step towards
tumor characterization and real-time monitoring in a minimally invasive fashion. Extracellular vesicles (EVs) are released from
tumor cells into body fluids and can provide a powerful platform for
tumor biomarkers because they carry
tumor proteins and
nucleic acids. Detecting rare point mutations in the background of wild-type sequences in biofluids such as blood and cerebrospinal fluid (CSF) remains a major challenge. Techniques such as BEAMing (beads,
emulsion, amplification, magnetics) PCR and droplet digital PCR (ddPCR) are substantially more sensitive than many other assays for mutant sequence detection. Here, we describe a novel approach that combines biofluid EV
RNA and BEAMing RT-PCR (EV-BEAMing), as well droplet digital PCR to interrogate mutations from
glioma tumors. EVs from CSF of patients with
glioma were shown to contain mutant IDH1 transcripts, and we were able to reliably detect and quantify mutant and wild-type IDH1
RNA transcripts in CSF of patients with
gliomas. EV-BEAMing and EV-ddPCR represent a valuable new strategy for
cancer diagnostics, which can be applied to a variety of biofluids and
neoplasms.Molecular
Therapy-
Nucleic Acids (2013) 2, e109; doi:10.1038/mtna.2013.28; published online 23 July 2013.