Establishing a Robust Molecular Taxonomy for Diffuse Gliomas of Adulthood

Cellular Density in Adult Glioma, Estimated with MR Imaging Data and a Machine Learning Algorithm, Has Prognostic Power Approaching World Health Organization Histologic Grading in a Cohort of 1181 Patients

BACKGROUND AND PURPOSE

Recent advances in machine learning have enabled image-based prediction of local tissue pathology in gliomas, but the clinical usefulness of these predictions is unknown. We aimed to evaluate the prognostic ability of imaging-based estimates of cellular density for patients with gliomas, with comparison to the gold standard reference of World Health Organization grading.

MATERIALS AND METHODS

Data from 1181 (207 grade II, 246 grade III, 728 grade IV) previously untreated patients with gliomas from a single institution were analyzed. A pretrained random forest model estimated voxelwise tumor cellularity using MR imaging data. Maximum cellular density was correlated with the World Health Organization grade and actual survival, correcting for covariates of age and performance status.

RESULTS

A maximum estimated cellular density of >7681 nuclei/mm2 was associated with a worse prognosis and a univariate hazard ratio of 4.21 (P < .001); the multivariate hazard ratio after adjusting for covariates of age and performance status was 2.91 (P < .001). The concordance index between maximum cellular density (adjusted for covariates) and survival was 0.734. The hazard ratio for a high World Health Organization grade (IV) was 7.57 univariate (P < .001) and 5.25 multivariate (P < .001). The concordance index for World Health Organization grading (adjusted for covariates) was 0.761. The maximum cellular density was an independent predictor of overall survival, and a Cox model using World Health Organization grade, maximum cellular density, age, and Karnofsky performance status had a higher concordance (C = 0.764; range 0.748-0.781) than the component predictors.

CONCLUSIONS

Image-based estimation of glioma cellularity is a promising biomarker for predicting survival, approaching the prognostic power of World Health Organization grading, with added values of early availability, low risk, and low cost.

Toward a standard pathological and molecular characterization of recurrent glioma in adults: a Response Assessment in Neuro-Oncology effort

Regardless of subtype, diffuse gliomas of adulthood are characterized by inexorable progression through treatment. Cancer recurrence in the context of therapy is by no means unique to gliomas. For many tumors residing outside the central nervous system (CNS), tissue-based analyses are routinely employed to document the molecular and cellular features of disease recurrence. Such interventions are inconsistently applied for gliomas, however, and lack rigorous standardization when they are. While many of the reasons underlying these discrepancies reflect pragmatic realities inherent to CNS disease, the suboptimal employment of histological and molecular assessment at recurrence nevertheless represents a missed opportunity to proactively guide patient management and increase knowledge. Herein, we address this quandary by pairing a succinct description of the histological, biological, and molecular characteristics of recurrent glioma with recommendations for how to better standardize and implement quality pathological assessment into patient management. We hope this review will prompt thoughtful revision of standard operating procedures to maximize the utility of glioma re-biopsy.

Nobiletin inhibits invasion via inhibiting AKT/GSK3β/β-catenin signaling pathway in Slug-expressing glioma cells

Epithelial-mesenchymal transition (EMT) is a pivotal event in tumor progression during which cancer cells undergo dramatic changes acquiring highly invasive properties. In this study, we found that nobiletin, a polymethoxylated flavone, suppressed migration and invasion in both U87 and U251 glioma cells. Expression of epithelial markers (E-cadherin and occludin) was upregulated; mesenchymal markers (N-cadherin, fibronectin) and the transcriptional factor Slug were downregulated after nobiletin treatment. Transforming growth factor β (TGF-β) was applied to stimulate EMT and the results showed that nobiletin not only influenced basal level cell migration but also prevented TGF-β-triggered migration and EMT, with the AKT/GSK3β/β-catenin signaling pathway greatly involved. Furthermore, nobiletin remarkably diminished TGF-β-induced β-catenin nuclear translocation and the binding to the Slug promoter. It is worth noting that nobiletin almost blocked invasion in Slug-expressing U87 and U251 cells, and only exhibiting faint effect on non-Slug-expressing U343 glioma cells. Reinforced Slug expression in U343 cells by transfecting Slug plasmid was significantly attenuated by nobiletin, demonstrating the essential role of Slug in the anti-metastasis effect of nobiletin. Nobiletin repressed tumor growth in vivo and abrogated EMT in nude mice bearing U87-Luc xenografts, as demonstrated by Xenogen IVIS imaging and immunohistochemistry assay. Our findings suggested that nobiletin might have a great potential for treating glioblastoma.