Abstract 3147: Stereotactic image-guided epigenome profiling reveals a neural stem cell evolutionary origin of diffuse gliomas
Authors: Barthel Floris P. , Verburg Niels , Rockne Russell , Eijgelaar Roelant , Anderson Kevin , Müller Domenique , Branciamore Sergio , Johnson Kevin C. , Wesseling Pieter , Hamer Philip C. de Witt , Verhaak Roel G. 
Published: July 2021

Abstract
Diffuse gliomas are malignant neoplasms originating in the parenchyma of the central nervous system whose cellular origin remains elusive. To determine the cellular and spatiotemporal origin of gliomas, we devised a three-dimensional reconstruction of tumor lineage. We used neuronavigation to acquire eight to twelve image-guided and spatially separated stereotactic biopsy samples from 16 adult patients with a diffuse glioma, which we characterized using DNA methylation arrays. A total of 133 samples were obtained from regions with and without imaging abnormalities. Methylation profiles were analyzed to construct phyloepigenetic trees and subsequently projected on 3D image-derived tumor maps.
Lineage analysis of these evolutionary trees indicated that the sampled gliomas largely evolved stochastically, suggesting that critical tumor drivers were acquired early in time. These results were further validated using 102 multi-region samples from 24 independent patients. Patristic (evolutionary) and cartesian (spatial) distances between pairs of tumor samples from the same patient demonstrated strong correlations, suggesting that this information could be used to determine trajectories of tumor evolution. Evolutionary and spatial distance metrics were combined with histologically obtained and computationally quantified cellularity and proliferation rates to model the direction and magnitude of tumor growth. In order to relate tumor lineage to brain anatomy we mapped patient imaging to a reference space (Montreal Neurological Institute, MNI). Samples mapping to regions of white matter were earlier in tumor lineage when compared to samples mapping to regions of gray matter, suggesting that white matter involvement is an early feature of tumor development. Samples early in tumor lineage were located closer to the ventricles when compared with samples late in lineage, suggesting that tumors grow outward from the ventricular lining. Finally, we used a tumor probability map constructed using imaging from over 500 unrelated patients to associate lineage to tumor probability. Results from this analysis indicated that periventricular areas of high tumor probability coincided with samples early in tumor lineage and cortical areas of low tumor probability coincided with samples late in tumor lineage. Taken together, our phylogeographic analysis of tumor development supports a neural progenitor cell-of-origin model, where neural stem cells in the subventricular zone of the lateral ventricles give rise to mature tumors.
Citation Format: Floris P. Barthel, Niels Verburg, Russell Rockne, Roelant Eijgelaar, Kevin Anderson, Domenique Müller, Sergio Branciamore, Kevin C. Johnson, Pieter Wesseling, Philip C. de Witt Hamer, Roel G. Verhaak. Stereotactic image-guided epigenome profiling reveals a neural stem cell evolutionary origin of diffuse gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3147.