PATH-29. Rapid gene analysis for intraoperative decision-making during removal of diffuse glioma

Abstract The 5th edition of the World Health Organization (WHO) Classification of Tumours of Central Nervous System (CNS) tumours (WHO CNS 5) introduced subclassification of tumors using important molecular markers. In adult-type diffuse gliomas, Isocitrate dehydrogenase (IDH) mutation and telomerase reverse transcriptase (TERT) promoter mutations play pivotal roles in molecular classification. Herein, we aimed to develop a rapid genotyping system using a GeneSoC based on real-time polymerase chain reaction (PCR) with microfluidic thermal cycling, which enables 50-cycles PCR within 20 minutes. To determine analysis condition, we analyzed frozen tumor tissues derived from 67 cases and artificial DNA vector using this system. We could detect at least 5% variant allele frequency of IDH R132H mutation or TERT promoter C228T/C250T mutation. Next, we analyzed 117 cases intra-operatively using this system. After tumor collection we could obtain genotyping of IDH1 R132H for 21.86 minutes or those of TERT C228T/C250T for 24.72 minutes, respectively (n=10). Sensitivity and specificity of IDH1 R132H are 0.979 and 0.984, respectively. Also, those of TERT promoter C228T/C250T are 1.000 and 1.000, respectively. These mutations could be detected within approximately 25 minutes after collection of tumor tissue, intra-operatively. This system is effective for intraoperative diagnosis of astrocytoma, IDH-mutant and oligodendroglioma, IDH-mutant and 1p/19q-codeleted during removal of lower grade diffuse glioma. Also, during removal of diffuse glioma with IDH mutation, we could detect tumor boundary where the IDH1 R132H status turned out to be wild-type, intra-operatively. A rapid genotyping system using GeneSoC might be effective not only for the intra-operative diagnosis of diffuse glioma but also for detection of tumor boundary.