P.044 Prospective clinical detection of 2-hydroxyglutarate to predict IDH-mutant gliomas using magnetic resonance spectroscopy: preliminary results

Background: With the advent of the 2016 WHO classification of tumours, prognostically distinct subclasses of glioma have been revealed. A subset of gliomas which harbor the isocitrate dehydrogenase (IDH) mutation have a survival advantage. 2-Hydroxyglutarate (2-HG) is a byproduct of faulty IDH metabolism in IDH mutants making it an ideal tumour biomarker. Since pre-operative detection of this metabolite using magnetic resonance spectroscopy (MRS) may yield valuable information for the neurosurgeon, we undertook the first Canadian utility study to detect 2-HG via MRS. Methods: We will recruit 150 patients presenting with a newly suspected glioma. All patients will undergo MRS scans for 2-HG pre-operatively and the neuropathologist will determine IDH status post-operatively based on immunohistochemistry and DNA sequencing. Pre-operative detection of 2-HG will be compared to post-operative IDH status. Results: To date, of 34 eligible subjects, 29 have glioma determined by pathology. Seven of these were IDH-mutant positive by pathology, of which 3 were detected by MRS. One glioma positive for 2-HG on MRS turned out to be IDH mutant negative on pathology. Conclusions: Prospective detection of 2-HG via MRS is feasible in the clinical setting. Additional subjects as well as refinement of our MRS protocol may yield higher sensitivity and specificity of this novel and clinically relevant diagnostic tool.