No abstract

Background The detection of somatic mutations in cell-free DNA (cfDNA) from liquid biopsy has emerged as a non-invasive tool to monitor the follow-up of cancer patients. However, the significance of cfDNA clinical utility remains uncertain in patients with brain tumors, primarily because of the limited sensitivity cfDNA has to detect real tumor-specific somatic mutations. This unresolved challenge has prevented accurate follow-up of glioma patients with non-invasive approaches. Methods Genome-wide DNA methylation profiling of tumor tissue and serum cell-free DNA of glioma patients. Results Here, we developed a non-invasive approach to profile the DNA methylation status in the serum of patients with gliomas and identified a cfDNA-derived methylation signature that is associated with the presence of gliomas and related immune features. By testing the signature in an independent discovery and validation cohorts, we developed and verified a score metric (the “glioma epigenetic liquid biopsy score” or GeLB) that optimally distinguished patients with or without glioma (sensitivity: 100%, specificity: 97.78%). Furthermore, we found that changes in GeLB score reflected clinicopathological changes during surveillance (e.g., progression, pseudoprogression or response to standard or experimental treatment). Conclusions Our results suggest that the GeLB score can be used as a complementary approach to diagnose and follow up patients with glioma.

Transition metals are essential, but deregulation of their metabolism causes toxicity. Here, we report that the compound NSC319726 binds copper to induce oxidative stress and arrest glioblastoma-patient-derived cells at picomolar concentrations. Pharmacogenomic analysis suggested that NSC319726 and 65 other structural analogs exhibit lethality through metal binding. Although NSC319726 has been reported to function as a zinc ionophore, we report here that this compound binds to copper to arrest cell growth. We generated and validated pharmacogenomic predictions: copper toxicity was substantially inhibited by hypoxia, through an hypoxia-inducible-factor-1α-dependent pathway; copper-bound NSC319726 induced the generation of reactive oxygen species and depletion of deoxyribosyl purines, resulting in cell-cycle arrest. These results suggest that metal-induced DNA damage may be a consequence of exposure to some xenobiotics, therapeutic agents, as well as other causes of copper dysregulation, and reveal a potent mechanism for targeting glioblastomas.

SummaryWe leveraged IDH wild type glioblastomas and derivative neurospheres to define tumor-intrinsic transcription phenotypes. Transcriptomic multiplicity correlated with increased intratumoral heterogeneity and tumor microenvironment presence. In silico cell sorting demonstrated that M2 macrophages/microglia are the most frequent type of immune cells in the glioma microenvironment, followed by CD4 T lymphocytes and neutrophils. Hypermutation associated with CD8+ T cell enrichment. Longitudinal transcriptome analysis of 124 pairs of primary and recurrent gliomas showed expression subtype is retained in 53% of cases with no proneural to mesenchymal transition being apparent. Inference of the tumor microenvironment through gene signatures revealed a decrease in invading monocytes but a subtype dependent increase in M2 macrophages/microglia cells after disease recurrence. All expression datasets are accessible through http://recur.bioinfo.cnio.es/.SignificanceIDH wild type glioblastoma expression phenotypes have been related to tumor characteristics including genomic abnormalities and treatment response. We explored the intratumoral transcriptomic landscape, including a definition of tumor-intrinsic gene expression subtypes and how they relate to the different cellular components of the tumor immune environment. Comparison of matching primary and recurrent gliomas provided insights into the treatment-induced phenotypic tumor evolution. Proneural to mesenchymal transitions have long been suspected but were not apparent, while intratumoral heterogeneity was a predictor of subtype transition upon recurrence. Characterizing the evolving glioblastoma transcriptome en tumor microenvironment aids in designing more effective immunotherapy trials. Our study provides a comprehensive transcriptional and cellular landscape of IDH wild type GBM during treatment modulated tumor evolution.HighlightsNext generation GBM-intrinsic transcriptional subtypes: proneural, classical, mesenchymalM2 macrophages, CD4+ T-lymphocytes and neutrophils dominate glioblastoma microenvironmentSensitivity to radiotherapy may associate with M2 macrophage presenceCD8+ T cells are enriched in hypermutated GBMs at diagnosis and recurrence

SUMMARYHistomorphology and current grading schemes are unable to predict glioma relapse and malignant tumor progression. We reported that the IDH-mutant associated Glioma-CpG Island Methylator Phenotype (G-CIMP) can be further divided into two clinically distinct subtypes independent of histopathological grading (G-CIMP-high and -low) with evidence of correlation with tumor progression. Here we performed a comprehensive epigenomic analysis of 74 longitudinally collected glioma samples (grade II-IV) to understand malignant recurrence from G-CIMP-high to G-CIMP-low. G-CIMP-low recurrence appeared in 12% of all gliomas and resemble IDH-wildtype primary glioblastoma. G-CIMP-low recurrence can be characterized by distinct epigenetic changes at candidate functional tissue enhancers with AP-1/SOX binding elements, stem cell-like epigenomic phenotype, and genomic instability. Finally, we defined a set of candidate biomarker signatures that predict recurrence of G-CIMP-low with clinically relevance on patient outcomes. Our study provides opportunity for refined clinical trial designs and therapeutic targets that limit progression to more aggressive G-CIMP-low phenotype.HIGHLIGHTSIndolent G-CIMP-high progresses to aggressive G-CIMP-low phenotypeIncidence of G-CIMP-low recurrent tumors are 3 times greater than G-CIMP-low primaryG-CIMP-low recurrent tumors share epigenomic features with IDH-wildtype primary GBMPredictive biomarkers of G-CIMP-low progression at primary diagnosis