BIOM-33. TEMPORAL HETEROGENEITY OF DNA METHYLATION SUBCLASSES BETWEEN MATCHED NEWLY DIAGNOSED AND RECURRENT IDH-WILDTYPE GLIOBLASTOMA

Abstract Spatiotemporal heterogeneity is a major factor contributing to the devastating prognosis of isocitrate-dehydrogenase (IDH)-wildtype glioblastoma. Genome-wide DNA methylation profiling allows stratification into several subgroups IDH-wildtype glioblastoma, which were shown have spatial in newly diagnosed tumors. However, temporal and its clinical relevance remains inconclusive. Tumor tissue obtained from first recurrence surgery 31 patients with glioblastoma was subjected profiling. profiles analyzed for correlated data, survival outcome copy number variations. In addition, deconvolution immune cells unsupervised hierarchical clustering using pairwise Pearson correlation coefficients 10.000 most variable CpG features performed. Of all matched tumor tissue, 4 (12.9%) had non-matching brain classifier output at recurrence. Within remaining 27 patients, transition dominant subclass observed 8 (29.6%) glioblastomas frequent mesenchymal (62.5%). A more likely after incomplete removal contrast-enhanced parts (p = 0.04). location, adjuvant treatment, time between primary did not influence transition. Immune cell proportions purity or specific sites Survival analyses revealed comparable without Our findings demonstrate subclasses 29.6% We identified factors showed that impact outcome. possible must be taken consideration future targeted therapies