Diagnosis of glioma tumors using circulating cell-free DNA

Introduction

Gliomas are the most frequent brain tumors, making up about 30% of all brain and central nervous system tumors. Existing standard diagnostic technique for glioma tumor includes tissue biopsy, which is a highly invasive and hence a risky technique for the patient’s survival. ‘Liquid biopsy’ is a new and recently developed non-invasive cancer diagnostic technique, which includes use of circulating cell-free DNA (cfDNA) fragments for tracing tumor markers.

Our goal is to do comprehensive study between distinct types of glioma cancer tumors and cfDNA of respective patients, to elucidate the scope of cfDNA in liquid biopsy.

Methods

We collected 17 glioma patient’s tumor biopsy, plasma and buffy coat samples, plus 14 healthy person`s plasma and buffy coat samples. Tumor DNA was isolation from tumor biopsy, cfDNA from patient’s plasma and healthy person`s plasma, germline DNA was isolated from patient`s and healthy person`s buffy coat samples, then deeply sequenced on Illumina HiSeq 2500. NGS data was analyzed to find out SNVs as well as structural variants and copared between cfDNA, tumor DNA and WBC DNA.

Results

We have successfully detected glioma specific mutations such as IDH1, IDH2, PDGFRA, NOTCH1, PIK3R1 and TP53, on cfDNA isolated from glioma patient`s plasma and could relate this mutations to the different tumor grades of glioma.

Discussion

This study may help in developing liquid biopsy technique for glioma tumor diagnosis and in its prognosis for monitoring the glioma treatment by non-invasive approach, and will eventually help physicians to decide right treatment on appropriate time.