H3.3K27M Mutation Promotes The Migration and Invasion of Glioma Cells By Activating β-Catenin/USP1 Signaling

H3.3K27M is a newly identified molecular pathology marker in glioma and is especially correlated with the malignancy of diffuse intrinsic pontine glioma (DIPG). In recent years, accumulating research has revealed that other types of glioma also contain the H3.3K27M mutation. However, the role of H3.3K27M in high-grade adult glioma, which is the most malignant glioma, has not been investigated. In this study, we focused on exploring the expression and function of H3.3K27M in high-grade adult glioma patients. We found that H3.3K27M is partly highly expressed in high-grade glioma tissues. Then, we introduced H3.3K27M into H3.3 wild-type glioma cells, U87 cells and LN229 cells. We found that H3.3K27M did not regulate the growth of glioma in vitro and in vivo; however, the survival of mice with transplanted tumors was significantly reduced. Further investigation revealed that H3.3K27M expression mainly promoted the migration and invasion of glioma cells. Moreover, we certified that H3.3K27M overexpression enhanced the protein levels of ꞵ-catenin and p-ꞵ-catenin, the protein and mRNA levels of ubiquitin-specific protease 1 (USP1), and the protein level of enhancer of zeste homolog 2 (EZH2). Importantly, the ꞵ-catenin inhibitor XAV-939 significantly attenuated the upregulation of the aforementioned proteins. Overall, the H3.3K27M mutation is present in a certain proportion of high-grade glioma patients and facilitates a poor prognosis by promoting the metastasis of glioma by regulating the ꞵ-catenin/USP1/EZH2 pathway.

BIOM-43. CROSS-PLATFORM ROBUSTNESS IN THE GLUCOCORTICOID RESPONSE PHARMACODYNAMIC BIOMARKER

The neutrophil dexamethasone methylation index (NDMI) is an algorithm-based biomarker to assess individuals’ exposures to dexamethasone, a synthetic glucocorticoid commonly administered for inflammation. Cortisol is the main endogenous glucocorticoid that controls vital processes including the immune response and lipid and carbohydrate metabolism. Variations in the NDMI score reflect individuals’ sensitivities of exposures to both exogenous and endogenous glucocorticoids, and this biomarker was trained using elastic net regression on Illumina’s most recent DNA methylation beadarray, the EPIC array, which contains 850,000 cytosine-guanine (CpG) sites. While technology for microarray research continues to advance over time, researchers are capable of conducting more comprehensive epigenome-wide association studies (EWAS). However, many studies are still run and archived using Illumina’s historical 450K platform with approximately 450,000 CpGs, and there are fewer published databases using the 850K EPIC array. To evaluate the cross-platform bioinformatic comparability, we performed elastic net regression modeling using predictors available in the 450K to train the NDMI. Among the 135 pre-surgery glioma cases from the UCSF Immune Profiles Study (IPS), NDMI scores between the 450K and 850K model were strongly correlated (r = 0.99, p < 0.0001). In the 311 controls from the UCSF Adult Glioma Study (AGS), similar correlations were observed (r = 0.96, p < 0.0001). We observe that NDMI remains a robust tool using historical 450K data and conclude that this algorithmic tool is capable of detecting the variations in individuals’ responses to dexamethasone.

Safety and Efficacy of Procarbazine and Lomustine Chemotherapy as a Salvage Treatment for Recurrent Adult Glioma

PurposeWhile procarbazine, lomustine, and vincristine (PCV) chemotherapy is considered a salvage option for adult glioma, whether vincristine included in this regimen is beneficial is uncertain due to its potential toxicity and uncertain efficacy. In this study, we evaluated the safety and efficacy of PC chemotherapy in contrast with those of PCV chemotherapy. MethodsUsing electronic medical records, all patient with adult recurrent glioma who received PC or PCV chemotherapy between 2009 and 2020 at Seoul St. Mary’s Hospital or St. Vincent’s Hospital were examined retrospectively. A total of 59 patients met our eligibility criteria. Among them, 15 patients received PC chemotherapy (PC group) and 44 patients received PCV chemotherapy (PCV group). ResultsThe PC group presented a significantly lower hematology toxicity (anemia: 6.7% vs. 45.5%; p = 0.02 and thrombocytopenia: 20.0% vs. 70.4%; p < 0.001). Also, the clinical impacts of PC chemotherapy, including delay of a cycle, dose reduction, discontinuation of drug(s), or total cessation of chemotherapy, were significantly less frequent (26.7% vs. 68.2%; p = 0.012). The overall survival of PC group was significantly longer than that of PCV group (396 vs. 232 days; p = 0.042), while there was no significant difference in progression-free survival between two groups (284.5 vs. 131 days; p = 0.077). ConclusionThis is the first comparative study to suggest that PC chemotherapy leads to less toxicity than PCV chemotherapy without loss of clinical efficacy in patients with recurrent adult glioma. Further prospective and larger studies are needed to validate our findings.

Identification of characteristics that determine behavioral and personality changes in adult glioma patients

Background Glioma patients may experience behavioral and personality changes (BPC), negatively impacting their lives and that of their relatives. However, there is no clear definition of BPC for adult glioma patients, and here we aimed to determine which characteristics of BPC are relevant to include in this definition. Methods Possible characteristics of BPC were identified in the literature, and presented to patients and (former) caregivers in an online survey launched via the International Brain Tumour Alliance. Participants indicated the relevance for each characteristic, the three characteristics with most impact on their life, and missing characteristics. A cluster analysis and discussions with experts provided input to categorize characteristics and propose a definition for BPC. Results Completed surveys were obtained from 140 respondents; 35% patients, 50% caregivers and 15% unknown. Of 49 proposed characteristics, 35 were reported as relevant by at least 25% (range:7-44%) of respondents. Patients and caregivers rated different characteristics as most important. Common characteristics included in the top 10 of both patients and caregivers were lack of motivation, change in being socially active, not able to finish things and change in level of irritation. No characteristics were reported missing by ≥5 respondents. Three categories of BPC were identified: (1) emotions, needs and impulses (2) personality traits, and (3) poor judgement abilities. Conclusion The work resulted in a proposed definition for BPC in glioma patients, for which endorsement from the neuro-oncological community will besought. A next step is to identify or develop an instrument to evaluate BPC in glioma patients.

ECOA-10. Integrated genomic and clinical analysis of BRAF-mutated glioma in adults

BRAF alterations are recognized as a significant driver of disease in pediatric low-grade glioma (pLGG) but the implications of BRAF alterations on the natural history and response to treatment are unclear in adult glioma. We characterized the molecular and clinical features of a multi-institutional cohort of adults with BRAF-mutated gliomas. We identified patients with glioma containing BRAF alterations on sequencing in multi-institutional cohorts (Dana-Farber/Brigham Cancer Center, Johns Hopkins Hospital, GENIE, TCGA). BRAF alterations were grouped into previously defined classes: I (V600E; RAS-independent/dimerization-independent), II (RAS-independent/dimerization-dependent), III (RAS-dependent/dimerization-dependent) in addition to BRAF copy number gains, fusions, and other. We interrogated 289 BRAF-altered gliomas (199 patients &gt;=18yrs, 90 patients &lt;18yrs; range 0-85yrs), and observed histopathologic and molecular differences between BRAF-altered gliomas in adults versus pediatric patients. Amongst adults, the most common BRAF alterations were Class I followed by copy number gains, with glioblastoma (GBM) the most prevalent histology. In comparison, pediatric gliomas in our cohort frequently harbored Class I mutations followed by BRAF fusions, with primarily pilocytic astrocytoma and pLGG histologies. Principal component analysis and correlation analysis revealed molecular features associated with gliomas of different BRAF alterations and histologies, including mutation of NF1, a negative regulator of RAS, which was significantly associated with class II/III BRAF alterations (64.3%) and not observed in BRAFV600E-mutated gliomas (0%, n=62) (p&lt;0.0001). Demographic and molecular features were evaluated for correlates for adult glioma risk stratification. Comparative survival analysis showed no significant difference between adult GBM harboring Class I compared to other BRAF alterations, whereas young adult age (18-35yrs) was associated with improved outcomes (p&lt;0.05). Among 86 GBM patients with detailed clinicopathologic data, 7 received RAF-targeted therapy, with variable clinical response. This cohort of BRAF-altered adult gliomas demonstrates a broad range of molecular alterations with implications for treatment sensitivity and patient risk stratification.

Loss of H3K27 trimethylation is frequent in IDH1-R132H but not in non-canonical IDH1/2 mutated and 1p/19q codeleted oligodendroglioma: a Japanese cohort study

Oligodendrogliomas are defined by mutation in isocitrate dehydrogenase (NADP(+)) (IDH)1/2 genes and chromosome 1p/19q codeletion. World Health Organisation diagnosis endorses testing for 1p/19q codeletion to distinguish IDH mutant (Mut) oligodendrogliomas from astrocytomas because these gliomas require different treatments and they have different outcomes. Several methods have been used to identify 1p/19q status; however, these techniques are not routinely available and require substantial infrastructure investment. Two recent studies reported reduced immunostaining for trimethylation at lysine 27 on histone H3 (H3K27me3) in IDH Mut 1p/19q codeleted oligodendroglioma. However, the specificity of H3K27me3 immunostaining in this setting is controversial. Therefore, we developed an easy-to-implement immunohistochemical surrogate for IDH Mut glioma subclassification and evaluated a validated adult glioma cohort. We screened 145 adult glioma cases, consisting of 45 IDH Mut and 1p/19q codeleted oligodendrogliomas, 30 IDH Mut astrocytomas, 16 IDH wild-type (Wt) astrocytomas, and 54 IDH Wt glioblastomas (GBMs). We compared immunostaining with DNA sequencing and fluorescent in situ hybridization analysis and assessed differences in H3K27me3 staining between oligodendroglial and astrocytic lineages and between IDH1-R132H and non-canonical (non-R132H) IDH1/2 Mut oligodendroglioma. A loss of H3K27me3 was observed in 36/40 (90%) of IDH1-R132H Mut oligodendroglioma. In contrast, loss of H3K27me3 was never seen in IDH1-R132L or IDH2-mutated 1p/19q codeleted oligodendrogliomas. IDH Mut astrocytoma, IDH Wt astrocytoma and GBM showed preserved nuclear staining in 87%, 94%, and 91% of cases, respectively. A high recursive partitioning model predicted probability score (0.9835) indicated that the loss of H3K27me3 is frequent to IDH1-R132H Mut oligodendroglioma. Our results demonstrate H3K27me3 immunohistochemical evaluation to be a cost-effective and reliable method for defining 1p/19q codeletion along with IDH1-R132H and ATRX immunostaining, even in the absence of 1p/19q testing.