The "Liquid Biopsy": the Role of Circulating DNA and RNA in Central Nervous System Tumors

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Web End = Curr Neurol Neurosci Rep (2016) 16: 25

DOI 10.1007/s11910-016-0629-6

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Web End = NEURO-ONCOLOGY (LE ABREY, SECTION EDITOR)

The BLiquid Biopsy^: the Role of Circulating DNA and RNA in Central Nervous System Tumors

Ian D. Connolly1,3,6 & Yingmei Li1,3 & Melanie Hayden Gephart1,4 & Seema Nagpal2,5

Published online: 2 February 2016# Springer Science+Business Media New York 2016

Abstract The detection of tumor-derived circulating nucleic acids in patients with cancer, known as the Bliquid biopsy,^ has expanded from use in plasma to other bodily fluids in an increasing number of malignancies. Circulating nucleic acids could be of particular use in central nervous system tumors as biopsy carries a 5-7 % risk of major morbidity. This application presents unique challenges that have limited the use of cell-free DNA and RNA in the diagnosis and monitoring of CNS tumors. Recent work suggests that cerebrospinal fluid may be a useful source of CNS tumor-derived circulating nucleic acids.

In this review, we discuss the available data and future outlook on the use of the liquid biopsy for CNS tumors.

Keywords cfDNA . miRNA . Brain tumor . Liquid biopsy . Circulating tumor cells

AbbreviationsBBB Blood-brain barrier miRNA micro RNAGBM GlioblastomaCNS Central nervous system CSF Cerebral spinal fluid cfDNA Cell-free DNACTCs Circulating tumor cells ddPCR Digital droplet PCR mtDNA Mitochondrial DNA

Introduction

A Bliquid biopsy,^ sampling of a brain tumors genetic profile through access to blood, urine, or cerebral spinal fluid (CSF), would obviate the need for a percutaneous or open biopsy of certain central nervous system (CNS) tumors. A reliable test identifying a specific tumors genetic signature could spare many patients an invasive and potentially morbid CNS procedure. Over the past decade, a wide variety of Bliquid biopsies^ have made their way from the laboratory into the clinical setting: the detection of viral DNA in CSF for the diagnosis of herpes encephalitis in 1990, circulating tumor cells (CTCs) for cancer patients in 2004, and fetal DNA aneuploidy screening for pregnant women in 2011 [13]. These techniques may have additional advantages over the traditional biopsy, including the ability to obtain multiple, sequential...