BIOS-05. SANGER SEQUENCING AND COPY-NUMBER ALTERATION ANALYSIS WITH MLPA CAN CLINICALLY CLASSIFY IDH-WILD-TYPE LOWER-GRADE ASTROCYTOMA

Abstract

Abstract The IDH-wild-type lower-grade astrocytomas are a heterogeneous entity. According to 2021 WHO classification, IDH-wild-type astrocytomas with any of the following factors show poor prognosis: combination of chromosome 7 gain and 10 loss (+7/-10), and/or EGFR amplification, and/or TERT promoter (TERTp) mutation. Multiplex ligation-dependent probe amplification (MLPA) can detect copy number alterations with a reasonable cost. The purpose of this study was to find precise and cost-effective method for stratifying the prognosis of IDH-wild-type astrocytomas. Sanger sequencing, MLPA, and quantitative methylation-specific PCR were performed for 42 IDH-wild-type lower-grade astrocytomas surgically treated at Kyoto University Hospital, and overall survival was analyzed for 40 patients. Of the 42 IDH-wild-type astrocytomas, 21 were classified as grade 4 in 2021 WHO classification and all of them had either TERTp mutation or EGFR amplification. Kaplan-Meier analysis confirmed the prognostic significance of 2021 WHO Classification, and WHO grade was also prognostic. Cox regression hazard model identified PTEN loss and PDGFRA amplification as independent significant prognostic indicators (Risk ratio of 9.75, p< 0.001 and 13.9, p=0.002). The classification recommended by 2021 WHO Classification could be completed using Sanger sequencing and MLPA. Survival analysis revealed PTEN and PDGFRA were significant prognostic factors for IDH-wild-type lower-grade astrocytomas.