Astrocytoma Research Articles

TREATMENT OPTIONS FOR RECURRENT MALIGNANT DIFFUSE ASTROCYTOMA (WHO GRADE IV)

Objectives We present the case of a 37-year-old female who underwent partial resection in 2018 for a diffuse fibrillary astrocytoma (WHO II) that invaded almost the entire right cerebral hemisphere. The patient followed conventional radiotherapy and chemotherapy. She presents after 6 years of regularly follow-ups with left hemiparesis, intracranial hypertension syndrome and tumor recurrence on MRI. The patient underwent another surgical intervention and the new histopathological diagnosis was diffuse astrocytoma grade IV. Therapeutic options for these patients are limited considering the fact that a gross total resection or a conventional re-irradiation could impact the quality of life. Therefore, exploring new therapeutic methods, such as targeted molecular therapy like EGFR antagonists or proteasome inhibitors, or proton therapy, should be considered. Material and Methods We conducted extensive research in two public medical databases for information related to the molecular pathways and management of primary and recurrent malignant astrocytoma and relevant articles were selected. Subsequently, we correlated this information with our direct experience in our case and discussed the observed results. Results Treatment modalities for these patients include reintervention, re-irradiation and second line chemotherapeutics. In relapsing cases the goal of reintervention is both to alleviate symptoms and obtain tumoral tissue for immunohistochemical analysis for identification of the new mutations. Conventional re-irradiation for large lesions carries high risks of producing both short-term and long-term side effects, impacting the quality of life. Alternatively, proton therapy minimizes the risk of adverse events due to Bragg peak reducing the irradiation of the surrounding tissue. Conclusions Genetic characterization of these lesions can facilitate targeted molecular therapy and help in establishing the prognosis. Re-irradiation of malignant astrocytomas with proton therapy is an effective treatment measure allowing for comparable tumor control to conventional radiotherapy.

Surrogate immunohistochemistry markers in adult gliomas – Experience in a tertiary care hospital

Objectives: The recent World Health Organization classification has recommended the usage of surrogate immunohistochemical markers for molecular classification of gliomas. However, only a few studies have attempted to study the expression of the entire panel of markers. The current study was undertaken to study the association of recognized surrogate immunohistochemical markers (isocitrate dehydrogenase 1 [IDH-1], alpha-thalassemia mental retardation X-linked [ATRX] and p53) in different histological lineages and grades of adult gliomas. Materials and Methods: This study was conducted on 118 cases of adult gliomas diagnosed on histopathology over a 2-year duration in a tertiary care hospital. The expression of surrogate immunohistochemistry markers (IDH-1, ATRX, and p53) in these cases was studied. Statistical analysis: Descriptive statistical analysis with the Statistical Package for the Social Science system version 17.0. Results: The frequency of IDH-1 positivity was significantly higher in oligodendrogliomas (OG: 76.5%; oligoastrocytoma: 100%) versus astrocytoma (AS) (grades 2 and 3: 48.1%). It was also significantly higher in diffuse gliomas (grades 2 and 3) versus glioblastomas (64% vs. 16.9%). Among IDH-mutant diffuse gliomas, ATRX loss was significantly higher in AS versus OGs (84.6% vs. 7.7%). P53 overexpression correlated significantly with histological subtype (AS 2,3: 55.6% vs. OG: 5.9%). Conclusions: The surrogate immunohistochemical panel of IDH-1, ATRX, and p53 showed significant association with distinct histopathological subtypes and is helpful in molecular stratification. Cut-offs of ≥ 10% nuclear positivity for p53 and 50% loss of nuclear ATRX expression showed a good correlation.

Practical Nomograms and Risk Stratification System for Predicting the Overall and Cancer-specific Survival in Patients with Anaplastic Astrocytoma

ObjectiveAnaplastic astrocytoma (AA) is an uncommon primary brain tumor with highly variable clinical outcomes. Our study aimed to develop practical tools for clinical decision-making in a population-based cohort study. MethodsData from 2997 patients diagnosed with AA between 2004 and 2015 were retrospectively extracted from the Surveillance, Epidemiology, and End Results (SEER) database. The LASSO and multivariate Cox regression analyses were applied to select factors and establish prognostic nomograms. The discriminatory ability of these nomogram models was evaluated using the concordance index (C-index) and receiver operating characteristic curve (ROC). Risk stratifications were established based on the nomograms. ResultsSelected 2997 AA patients were distributed into the training cohort (70%, 2097) and the validation cohort (30%, 900). Age, household income, tumor site, extension, surgery, radiotherapy, and chemotherapy were identified as independent prognostic factors for both overall survival (OS) and cancer-specific survival (CSS). In the training cohort, our nomograms for OS and CSS exhibited good predictive accuracy with C-index values of 0.752 (95% CI: 0.741–0.764) and 0.753 (95% CI: 0.741–0.765), respectively. Calibration and DCA curves showed that the nomograms demonstrated considerable consistency and satisfactory clinical utilities. With the establishment of nomograms, we stratified AA patients into high- and low-risk groups, and constructed risk stratification systems for OS and CSS. ConclusionsWe constructed two predictive nomograms and risk classification systems to effectively predict the OS and CSS rates in AA patients. These models were internally validated with considerable accuracy and reliability and might be helpful in future clinical practices.

Can the metabolic characteristics of diffuse glioma on <sup>11</sup>C-methionine PET/CT serve as a marker of its IDH status? Cross sectional study

INTRODUCTION: Since 2016, molecular markers, in particular, mutations in isocitrate dehydrogenase (IDH) 1 and 2, have been introduced as a classifying feature of cerebral gliomas that provided superior prognostication. The search for non-invasive biomarkers of the molecular profile of gliomas is necessary to improve the quality of preoperative diagnostics, identify patients with good and poor prognosis and determine treatment tactics.OBJECTIVE: Was to study the relationship between the IDH genotype of diffuse cerebral gliomas and metabolic biomarkers according to the results of PET/CT with [11C]methionine.MATERIALS AND METHOD: The results of PET/CT with 11C-methionine were identified to a retrospective analysis of 260 patients aged 18 to 75 years (median 40 years) with untreated cerebral glioma. Based on histological and molecular genetic studies of the surgical material including the determination of a mutation in the isocitrate dehydrogenase 1 (IDH1132H) gene, diffuse gliomas were classified according to the 2016 WHO classification of CNS tumors. Metabolic biomarkers included the calculation of tumor-to-brain ratio of 11С-methionine (TBRmax, TBRpeak and TBRmean) as well as the metabolic tumor volume (MTV). Statistics. Non-parametric tests were performed to compare the differences among patient groups. ROC curve analysis was performed to screen the optimal parameter and its best cutoff value for the discrimination of glioma genotype. All data analyses were performed using “Statistica 10,0” and “MedCalc” ststistical software. p-values less than 0.05 were considered statistically significant.RESULTS: According to the 2016 WHO classification astrocytic and oligodendroglial tumors of the adult type were divided into three groups: astrocytic gliomas with a mutation in the IDH1 gene (IDH1 mut) (n=95), astrocytic gliomas without a mutation in the IDH1 gene (IDH1 wild type — IDH1 wt) (n=103), and IDH1-mutant oligodendrogliomas (n=62). Significant differences in all ratios between the three molecular groups of gliomas were established. TBRmax cutoff of 2.27 differentiated between IDH1 wt and IDH1 mut gliomas with a sensitivity of 61% and a specificity of 77% (area under curve — AUC 0.752). When considering subgroups of gliomas that are homogeneous in terms of the IDH1 status or Grade, the dependence of TBR on the glioma histotype and grading was additionally established. In IDH1 mut oligodendrogliomas, TBR was significantly higher than in mutant astrocytomas, and in IDH1 wt astrocytomas, significant differences in TBR were established between Grade 2 and Grade 3–4. TBRmax was not a predictor of glioma type according to the WHO 2016 classification due to significant overlap of individual of TBR values. But TBRmax allowed diagnosing a cluster of malignant gliomas, including glioblastoma and astrocytoma Grade 3 IDH wt, as well as oligodendroglioma Grade 3 IDH1 mut, with a sensitivity of 65% and a specificity of 89% (AUC 0.848) at a cutoff of TBR=2.7. A strong correlation between the three tumor-to-brain ratios allows any ratio to be used in diagnostics. There were no significant differences in MTV between molecular types of gliomas.DISCUSSION: Distinguishing glioma types based on the 2016 WHO classification of the CNS tumors on the basis of 11Cmethionine uptake seems to be not reliable due to many factors that affect its uptake. In astrocytomas high TBR is associated with malignant grade and wild type IDH1 gene. However, the lack of differences in TBR between these astrocytomas and Grade 3 IDH1-mutant oligodendrogliomas does not allow one to predict the IDH1 status of the tumor in the absence of other radiological signs of the glioma histotype. The absence of differences in TBR between Grade 2 and Grade 3 astrocytomas IDH1 mut supports the view that they are considered as a single subgroup of lower grade gliomas. CONCLUSION: PET/CT with 11C-methionine has limited potential to assess the IDH status of diffuse gliomas. High TBR is associated with malignant glioma with wild-type IDH1 gene or oligodendroglial structure.

Abstract 4731: Targeting Lon protease as novel strategy to treat aggressive IDH mutant diffuse malignant astrocytoma

Abstract While isocitrate dehydrogenase (IDH) wild-type and mutant malignant astrocytoma (IDHwt, IDHmt) are diffuse CNS tumors that have a high degree of parallelism with one another, including microvascular proliferation and necrosis, the IDHwt tumors clinically presents with a higher tumor grade and thus poorer prognosis and survival rate. Isocitrate dehydrogenase mutation (IDH) hinders the hypoxia response in gliomas and promotes an advantageous reduction in both tumor growth and treatment resistance. Since recurrence is high, adequate characterization and identification of potential novel molecular targets in IDHmt mutant diffuse glioma is integral for developing new therapeutic strategies for better control of tumor burden and, thus, improved outcomes. Our previous published work has shown that the hypoxia responsive LONP1 mitochondrial protease is involved in glioma growth and treatment resistance and that LONP1 inhibitors can augment the effect of chemotherapy in IDHwt models. Here, we highlight the downstream activity of LONP1 via the NRF2 pathway and how synergistically, along with the IDH mutation, LONP1 overexpression can promote the subsequent proneural to mesenchymal transition (PMT) induced by stress and other tumor microenvironment signals. By characterizing the interplay between LONP1 and IDH mutation in in-vitro models, we demonstrate that oxidative stress modulates both PMT and TMZ drug resistance. When translated to an in-vivo patient-derived, intracranial orthotopic xenograft model, LONP1 overexpression is associated with decreased survival.Based on our findings, future clinical translation includes the possibility of using LONP1 as a novel target to optimize the standard of care treatment in IDH mutant diffuse astrocytoma. Citation Format: Christopher Douglas, Shashi Jain, Naomi Lomeli, Thao Vu, James Pham, Daniela A. Bota. Targeting Lon protease as novel strategy to treat aggressive IDH mutant diffuse malignant astrocytoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4731.

Update for astrocytomas: medical and surgical management considerations.

Astrocytomas include a wide range of tumors with unique mutations and varying grades of malignancy. These tumors all originate from the astrocyte, a star-shaped glial cell that plays a major role in supporting functions of the central nervous system (CNS), including blood-brain barrier (BBB) development and maintenance, water and ion regulation, influencing neuronal synaptogenesis, and stimulating the immunological response. In terms of epidemiology, glioblastoma (GB), the most common and malignant astrocytoma, generally occur with higher rates in Australia, Western Europe, and Canada, with the lowest rates in Southeast Asia. Additionally, significantly higher rates of GB are observed in males and non-Hispanic whites. It has been suggested that higher levels of testosterone observed in biological males may account for the increased rates of GB. Hereditary syndromes such as Cowden, Lynch, Turcot, Li-Fraumeni, and neurofibromatosis type 1 have been linked to increased rates of astrocytoma development. While there are a number of specific gene mutations that may influence malignancy or be targeted in astrocytoma treatment, O 6-methylguanine-DNA methyltransferase (MGMT) gene function is an important predictor of astrocytoma response to chemotherapeutic agent temozolomide (TMZ). TMZ for primary and bevacizumab in the setting of recurrent tumor formation are two of the main chemotherapeutic agents currently approved in the treatment of astrocytomas. While stereotactic radiosurgery (SRS) has debatable implications for increased survival in comparison to whole-brain radiotherapy (WBRT), SRS demonstrates increased precision with reduced radiation toxicity. When considering surgical resection of astrocytoma, the extent of resection (EoR) is taken into consideration. Subtotal resection (STR) spares the margins of the T1 enhanced magnetic resonance imaging (MRI) region, gross total resection (GTR) includes the margins, and supramaximal resection (SMR) extends beyond the margin of the T1 and into the T2 region. Surgical resection, radiation, and chemotherapy are integral components of astrocytoma treatment.

A novel program of infiltrative control in astrocytomas: ADAM23 depletion promotes cell invasion by activating γ-secretase complex.

Infiltration is a life-threatening growth pattern in malignant astrocytomas and a significant cause of therapy resistance. It results in the tumor cell spreading deeply into the surrounding brain tissue, fostering tumor recurrence and making complete surgical resection impossible. We need to thoroughly understand the mechanisms underlying diffuse infiltration to develop effective therapies. We integrated in vitro and in vivo functional assays, RNA sequencing, clinical, and expression information from public data sets to investigate the role of ADAM23 expression coupling astrocytoma's growth and motility. ADAM23 downregulation resulted in increased infiltration, reduced tumor growth, and improved overall survival in astrocytomas. Additionally, we show that ADAM23 deficiency induces γ-secretase (GS) complex activity, contributing to the production and deposition of the Amyloid-β and release of NICD. Finally, GS ablation in ADAM23-low astrocytomas induced a significant inhibitory effect on the invasive programs. Our findings reveal a role for ADAM23 in regulating the balance between cell proliferation and invasiveness in astrocytoma cells, proposing GS inhibition as a therapeutic option in ADAM23 low-expressing astrocytomas.

Cell signaling activation and extracellular matrix remodeling underpin glioma tumor microenvironment heterogeneity and organization.

Tumor cells thrive by adapting to the signals in their microenvironment. To adapt, cancer cells activate signaling and transcriptional programs and migrate to establish micro-niches, in response to signals from neighboring cells and non-cellular stromal factors. Understanding how the tumor microenvironment evolves during disease progression is crucial to deciphering the mechanisms underlying the functional behavior of cancer cells. Multiplex immunohistochemistry, spatial analysis and histological dyes were used to identify and measure immune cell infiltration, cell signal activation and extracellular matrix deposition in low-grade, high-grade astrocytoma and glioblastoma. We show that lower grade astrocytoma tissue is largely devoid of infiltrating immune cells and extracellular matrix proteins, while high-grade astrocytoma exhibits abundant immune cell infiltration, activation, and extensive tissue remodeling. Spatial analysis shows that most T-cells are restricted to perivascular regions, but bone marrow-derived macrophages penetrate deep into neoplastic cell-rich regions. The tumor microenvironment is characterized by heterogeneous PI3K, MAPK and CREB signaling, with specific signaling profiles correlating with distinct pathological hallmarks, including angiogenesis, tumor cell density and regions where neoplastic cells border the extracellular matrix. Our results also show that tissue remodeling is important in regulating the architecture of the tumor microenvironment during tumor progression. The tumor microenvironment in malignant astrocytoma, exhibits changes in cell composition, cell signaling activation and extracellular matrix deposition during disease development and that targeting the extracellular matrix, as well as cell signaling activation will be critical to designing personalized therapy.

RADT-16. CLINICAL OUTCOMES FOR HIGH RISK WHO GRADE II GLIOMA PATIENTS TREATED WITH UPFRONT TMZ-BASED CHEMORADIOTHERAPY

Abstract OBJECTIVE RTOG 9802 demonstrated improved survival using chemoradiotherapy (CRT) over radiotherapy (RT) alone for WHO Grade II gliomas (LGG) using PCV with RT. We analyze our retrospective dataset of predominantly temozolomide (TMZ)-based CRT in LGG patients who would have been eligible for RTOG 9802. METHODS Retrospective review of LGG patients (2000–2017) treated at a single institution (67 patients). Histologies included oligodendroglioma(OD), astrocytoma(AC) or astrocytoma (OA). Those who received upfront RT +/- chemotherapy were included. The CRT cohort (n=40) consisted primarily of TMZ (n=36) administered concurrently with RT. 27 patients received RT alone. RT for both cohorts consisted of a median dose of 54 Gy (range 50.4 - 54 Gy). 65/67 patients had “high risk” LGG as defined by RTOG 9802 criteria. Kaplan Meier analysis was used to assess overall survival (OS) and progression free survival (PFS). RESULTS 5-year PFS for patients receiving CRT was 64% vs. 44% in those receiving RT alone (log rank p=0.009). Difference in PFS due to chemotherapy was driven by AC histology (57% vs. 21% PFS at 5 years, log rank p=0.002) while OD/OA PFS was not statistically altered (79% vs. 72% PFS at 5 years, p=0.21). 5-year OS for patients receiving CRT was 76% vs. 69% in those receiving RT alone (p=0.11). Cox Proportional Hazards analysis showed that use of upfront CRT (HR=0.4, p=0.009) was the only factor that decreased the risk of earlier progression. CONCLUSION Use of upfront, predominantly TMZ-based CRT, has a PFS benefit over RT alone in a population of WHO grade II gliomas. This benefit appears to be driven by AC histology and also appears to extend beyond the “very high risk” cohort from RTOG 0424 to include the “high risk” group from RTOG 9802.

NIMG-71. REAL-WORLD ASSESSMENT OF IDH1 INHIBITOR IVOSIDENIB IN IDH MUTANT LOWER GRADE GLIOMAS – THE JOHNS HOPKINS EXPERIENCE

Abstract BACKGROUND As clinical trials are ongoing to establish the role of IDH inhibitors in the treatment of lower-grade gliomas, long-term data is not yet available. Hence, here we share our real-world experience with off-label ivosidenib. METHODS In this single-institution retrospective analysis, we included chemo/radiotherapy-naïve, gadolinium non-enhancing WHO Grade 2/3 IDH1-mutated astrocytomas (AS) and oligodendrogliomas (OG) that were treated with off-label ivosidenib for ≥ 5 months for active tumor growth. We performed semi-automated volumetric analyses on T2/FLAIR images in 3D Slicer v4.11. Annualized growth-rates before and on ivosidenib were calculated, and time to initial response (reduction in growth-rate), growth arrest (growth-rate ≤ 0cc/yr) and shrinkage in patients with confirmatory data available (≥ 1 confirmatory follow-up scan). Progression-free survival (PFS), at 6 and 12 months were assessed (progression defined as ≥ 40% volume increase per RANO 3D). RESULTS We studied 12 patients (2F, median age 46yrs [range 26-60], 8/4 AS/OG; 4 grade 3) with an average of 17.2 months (5-33) follow-up on ivosidenib. Eleven (92%) patients had confirmatory data. Response rate was 82% (9/11) with median time of 4.9 (3.5-6.3) months to initial response and 11.1 (4.1-21.4) months to growth arrest. Growth arrest occurred 3-folds faster in OG than in AS (4.2±0.8 vs.12.5±4.2 months, p=0.014). Mean best response was 11.4±12.8% volume reduction, after a median of 12.1±9.3 months on ivosidenib. Mean PFS was 24.4 months (CI95%18.8-29.9). PFS-6 and PFS-12 were 91%, and 88% (7/8), respectively. No major toxicity was noted. There were 3 discontinuations, two for radiographic progression, one for increased seizure frequency. CONCLUSIONS In this small cohort, ivosidenib was well-tolerated with a high response rate; however, responses took up to a year to become evident and seemingly faster in oligodendrogliomas. These data suggest that ivosidenib might require more than 5 months of commitment and volumetrics may help the detection of early response.

Electromechanical Characterization of Human Brain Tissues: A Potential Biomarker for Tumor Delineation.

Accurate identification of surgical margins in brain tumors is of significant prognostic importance. Despite the availability of methods such as 5-ALA and image guidance, recognizing tumor boundary is highly subjective, dependant on recognizing subtle changes in tissue characteristics including texture and color to aid distinction. Design and development of a semi-automated system integrated with MEMS-based electromechanical sensors to enable an objective and reliable method of distinguishing tumors from normal brain tissue. Simultaneous electrical impedance and viscoelastic characterization of three types of freshly excised gliomas (glioblastoma (GBM), astrocytoma (AST), and oligodendroglioma (OLI)) (N = 8 each) and seventeen different normal brain regions (N = 6 each) obtained postmortem. The electrical impedance of gliomas (462±56Ω) was found to be significantly lower than corresponding normal (1267±515Ω) regions at 100kHz (p = 7.46e-11). The difference in the impedance between individual tumor types and corresponding normal regions was also statistically significant (p = 1e-8), suggesting accurate tumor delineation. There were distinct differences in the viscoelastic relaxation responses of high-grade and low-grade gliomas. White matter regions demonstrated higher impedance and faster stress relaxation compared to grey matter regions as a characteristic of their structural composition. We demonstrate that simultaneous electromechanical characterization of brain tumors and normal brain tissues can be an effective biomarker for tumor delineation, grading, and studying heterogeneity between the brain regions. The observations suggest the potential use of the technology in a clinical setting to achieve gross total resection and improve treatment outcomes by helping surgeons perform real-time risk evaluation during surgery.

Clinical Outcomes in High Risk WHO Grade II Glioma Patients Treated with Upfront TMZ-Based Chemoradiotherapy

<h3>Purpose/Objective(s)</h3> The RTOG 9802 study demonstrated improved survival with use of chemoradiotherapy (CRT) over radiotherapy (RT) alone for WHO Grade II gliomas (LGG). PCV chemotherapy, utilized in that trial, is less commonly used in the U.S. and is associated with significant toxicity. We analyze our retrospective dataset of predominantly temozolomide (TMZ)-based CRT in LGG patients who would have been eligible for RTOG 9802. <h3>Materials/Methods</h3> Retrospective review of LGG patients (2000–2017) in a single institution pathology database was performed. Patients with histologies that included oligodendroglioma (OD), astrocytoma (AC) or astrocytoma (OA) who received upfront RT +/- chemotherapy were included in the analysis. We identified 67 eligible patients during this interval. Characteristics including age>40, RTOG high-risk features (age≥40 at time of diagnosis OR lack of a gross total resection (GTR)), tumor size>6 cm, tumor crossing midline, pathology (n= 37 AC, 20 OD, or 9 OA), presence of neurologic deficit at diagnosis, and utilization of RT and chemotherapy were determined. The CRT cohort (n=40) consisted primarily of TMZ (n=36) administered concurrently with RT. 27 patients received RT alone. RT for both cohorts consisted of a median dose of 54 Gy (range 50.4 - 54 Gy). 65/67 patients had "high risk" LGG as defined by RTOG 9802 criteria. Kaplan Meier analysis was used to assess overall survival (OS) and progression free survival (PFS). <h3>Results</h3> 5-year PFS for patients receiving CRT was 64% vs. 44% in those receiving RT alone (log rank p=0.009). This PFS curve shows increased separation of curves after 2 years similar to what was seen in RTOG 9802. Difference in PFS due to chemotherapy was driven by AC histology (57% vs. 21% PFS at 5 years, log rank p=0.002) while OD/OA PFS was not statistically altered with the addition of chemotherapy (79% vs. 72% PFS at 5 years, p=0.21). 5-year OS for patients receiving CRT was 76% vs. 69% in those receiving RT alone (p=0.11), with the CRT arm not yet reaching median survival<b>.</b> Cox Proportional Hazards analysis revealed that patients with astrocytoma (HR=6.14, p=0.0034), neurological deficit at presentation (HR=2.37, p=0.023) and tumor>6 cm (HR=-2.69, p=0.03) had an increased risk of death. Cox Proportional Hazards analysis showed that use of upfront CRT (HR=0.4, p=0.009) was the only factor that decreased the risk of earlier progression. Patients with AC (HR=3.21, p-0.018) or neurological deficit at presentation (HR=2.49, p=0.01) had increased risk of progression. <h3>Conclusion</h3> Use of upfront predominantly TMZ-based CRT has a PFS benefit over RT alone in a population of WHO grade II gliomas. This benefit of upfront TMZ-based CRT, a regimen generally significantly less toxic than PCV and better tolerated, appears to extend beyond the "very high risk" cohort from RTOG 0424 to include the "high risk" group from RTOG 9802, indicating a potential role for TMZ in a larger subset of LGG patients than previously-thought. This benefit appears to be driven by AC histology.

Malignant transformation in low-grade astrocytoma for long-term monitoring.

Malignant transformation (MT) of low-grade astrocytoma (LGA) produces a poor prognosis in benign tumors. Currently, variables linked with MT of LGA have proven equivocal. The present study aims to evaluate the risk variables, indicating that LGA gradually differentiates to malignant astrocytoma. Retrospective cohort analysis of LGA patients was performed. Both univariate and multivariate studies were used to discover variables connected to MT using the Cox regression method. As a result, the cumulative incidence of MT for each covariate survival curve was built after the final model. In the current study, 115 individuals with LGA were included in the analysis, and MT was found in 16.5% of cases. In the case of MT, 68.4% of patients progressed to glioblastoma, whereas 31.6% progressed to anaplastic astrocytoma. Significant factors included supratentorial tumor (hazard ratio (HR) 3.41, 95% CI 1.18-12.10), midline shift > 5 mm (HR 7.15, 95% CI 2.28-34.33), and non-total resection as follows: subtotal resection (HR 5.09, 95% CI 0.07-24.02), partial resection (HR 1.61, 95% CI 1.09-24.11), and biopsy (HR 2.80, 95% CI 1.18-32.52). In individuals with LGA, MT dramatically altered the disease's natural history to a poor prognosis. The present study's analysis of the clinical features of patients indicated supratentorial LGA, a midline shift greater than 5 mm, and the degree of resection as risk factors for MT. The more extensive the resection, the greater the reduction in tumor load and MT. In addition, more molecular study is necessary to elucidate the pathophysiology of MT.

3D-volumetric assessment of response to ivosidenib in IDH-mutant gliomas.

2063 Background: Isocitrate Dehydrogenase (IDH) mutant gliomas represent a distinct class of primary brain tumors. Mutant IDH is a driver mutation implicated in gliomagenesis and a potential therapeutic target. Ivosidenib, an inhibitor of mutant IDH1, is currently being evaluated to treat gliomas. In the present study we assess our single-institutional experience with the off-label use of ivosidenib to reduce tumor growth rate in patients with IDH mutant gliomas. Methods: We have longitudinally analyzed the imaging of patients with histology-proven radio- and chemotherapy-naïve IDH-mutant WHO Grade 2 and 3 astrocytomas (AS) and oligodendrogliomas (OG) treated with off-label ivosidenib between 2019 and 2022. First, each patients’ FLAIR images were anonymized, bias-corrected, co-registered and semi-automatically segmented for volumetric analysis using 3D Slicer 4.11. MR acquisition dates were hidden, and the order of scans was randomized to prevent expectation bias. Volumetric trends and PFS were analyzed. Progressive disease was defined as a ≥40% increase in volume from baseline as per modified RANO criteria. Results: Eleven patients were included in the analysis (median age 46 years [range 26-62], 2F, 8AS/3OG, 7 Grade 2). Mean±SD follow-up time on ivosidenib was 16.1±15.5 months. Tumor volume reduction was noted in 82% of patients at least at one time point. Average volume change at best response was -11.4±12.8%. Mean time to best response was 12.1±9.3 months. PFS-6 and PFS-12 were 91% (n = 11), and 88% (n = 8), respectively. Mean PFS was 24.4 months (CI95% 18.8-29.9). Median PFS was not reached. Patients older than 45 years had significantly higher volume reduction compared to younger patients (18.9±6.3% vs. -2.4±13.2%;-p = 0.047, 2-tailed T-test). Ivosidenib was discontinued in in 2 patients for 2D radiographic changes, and in one for increased seizure frequency. Conclusions: The use of ivosidenib in treatment-naïve gliomas was associated with a high response rate; however, on average it required longer than a year to achieve best response. In this cohort, older patients had higher volume reduction. The drug was well tolerable. Further analysis of an expanded cohort is underway.

Mechanistic Elucidation of an Anti‐Epileptic for the Treatment of Glioblastoma

Glioblastoma multiforme (GBM) is a highly proliferative grade IV malignant astrocytoma with a 5‐year survival rate of ~5%. The current treatment strategies for GBM including surgery, radiation, and chemotherapy face multiple challenges such as resistance to standard chemotherapeutic temozolomide (TMZ), sensitive location, and presence of blood‐brain barrier that hinders permeation of various chemotherapeutics. The dire need and urgency to develop a new therapeutic for the treatment of GBM led us to explore metabolic vulnerabilities of cancer. Stiripentol (STP) is an FDA approved drug used for the treatment of Dravet’s syndrome (a rare type of epilepsy) and a putative LDH inhibitor that we screened out of many metabolic inhibitors for GBM. STP showed efficacy in cytotoxicity and proliferation assay on U87 and U138 GBM cells. STP also showed efficacy in clonogenic assay and wound healing assay in GBM cells. To further explore and discover the mechanistic target of STP for the treatment of GBM, we performed apoptosis assay, cell cycle assay, and studied the expression of proteins involved in apoptosis, metastasis, and cell signaling. In addition, 3D spheroid study was performed to mimic the tumor microenvironment and the effect of STP was assessed on the same. Next, synergy studies of STP with standard of care TMZ was performed on U87 cells. Cellular toxicity studies were performed to evaluate the safety profile of STP and the combination treatment with TMZ on normal human cells. We will elucidate mechanistic basis of STP anticancer activity in GBM cells and test preclinical potential of STP in tumor xenograft model. Therefore, STP is an effective compound that can augment TMZ for GBM treatment and merits further investigation.

The Diagnostic Significance of CXCL13 in M2 Tumor Immune Microenvironment of Human Astrocytoma.

Background: CXCL13 may act as a mediator of tumor-associated macrophage immunity during malignant progression. Objective: The present study clarifies the clinicopathological significances of CXCL13 and its corresponding trend with M2 macrophage in human astrocytoma. Methods: The predictive potential of CXCL13 was performed using 695 glioma samples derived from TCGA lower-grade glioma and glioblastoma (GBMLGG) dataset. CXCL13 and M2 biomarker CD163 were observed by immunohistochemistry in 112 astrocytoma tissues. Results: An in-depth analysis showed that CXCL13 expression was related to the poor prognosis of glioma patients (p = 0.0002) derive from TCGA analysis. High level of CXCL13 was detected in 43 (38.39%) astrocytoma and CXCL13/CD163 coexpression was expressed in 33 (29.46%) cases. The immunoreactivities of CXCL13 and CXCL13/CD163 were found in the malignant lesions, which were both significantly associated with grade, patient survival, and IDH1 mutation. Single CXCL13 and CXCL13/CD163 coexpression predicted poor overall survival in astrocytoma (p = 0.0039 and p = 0.0002, respectively). Multivariate Cox regression analyses manifested CXCL13/CD163 phenotype was a significant independent prognostic indicator of patient outcome in astrocytoma (CXCL13, p = 0.0642; CXCL13/CD163, p = 0.0368). Conclusion: CXCL13 overexpression is strongly linked to CD163+ M2 infiltration in malignant astrocytoma. CXCL13/CD163 coexpression would imply M2c-related aggressive characteristics existing in astrocytoma progression could also provide predictive trends of patient outcomes.

Risk Factors Associated with Malignant Transformation of Astrocytoma: Competing Risk Regression Analysis.

Background Malignant transformation (MT) of low-grade astrocytoma (LGA) triggers a poor prognosis in benign tumors. Currently, factors associated with MT of LGA have been inconclusive. The present study aims to explore the risk factors predicting LGA progressively differentiated to malignant astrocytoma. Methods The study design was a retrospective cohort study of medical record reviews of patients with LGA. Using the Fire and Gray method, the competing risk regression analysis was performed to identify factors associated with MT, using both univariate and multivariable analyses. Hence, the survival curves of the cumulative incidence of MT of each covariate were constructed following the final model. Results Ninety patients with LGA were included in the analysis, and MT was observed in 14.4% of cases in the present study. For MT, 53.8% of patients with MT transformed to glioblastoma, while 46.2% differentiated to anaplastic astrocytoma. Factors associated with MT included supratentorial tumor (subdistribution hazard ratio [SHR] 4.54, 95% confidence interval [CI] 1.08–19.10), midline shift > 1 cm (SHR 8.25, 95% CI 2.18–31.21), and nontotal resection as follows: subtotal resection (SHR 5.35, 95% CI 1.07–26.82), partial resection (SHR 10.90, 95% CI 3.13–37.90), and biopsy (SHR 11.10, 95% CI 2.88–42.52). Conclusion MT in patients with LGA significantly changed the natural history of the disease to an unfavorable prognosis. Analysis of patients' clinical characteristics from the present study identified supratentorial LGA, a midline shift more than 1 cm, and extent of resection as risk factors associated with MT. The more extent of resection would significantly help to decrease tumor burden and MT. In addition, future molecular research efforts are warranted to explain the pathogenesis of MT.

Bisulfite profiling of the MGMT promoter and comparison with routine testing in glioblastoma diagnostics

BackgroundPromoter methylation of the DNA repair gene O6-methylguanine-DNA methyltransferase (MGMT) is an acknowledged predictive epigenetic marker in glioblastoma multiforme and anaplastic astrocytoma. Patients with methylated CpGs in the MGMT promoter benefit from treatment with alkylating agents, such as temozolomide, and show an improved overall survival and progression-free interval. A precise determination of MGMT promoter methylation is of importance for diagnostic decisions. We experienced that different methods show partially divergent results in a daily routine. For an integrated neuropathological diagnosis of malignant gliomas, we therefore currently apply a combination of methylation-specific PCR assays and pyrosequencing.ResultsTo better rationalize the variation across assays, we compared these standard techniques and assays to deep bisulfite sequencing results in a cohort of 80 malignant astrocytomas. Our deep analysis covers 49 CpG sites of the expanded MGMT promoter, including exon 1, parts of intron 1 and a region upstream of the transcription start site (TSS). We observed that deep sequencing data are in general in agreement with CpG-specific pyrosequencing, while the most widely used MSP assays published by Esteller et al. (N Engl J Med 343(19):1350–1354, 2000. https://doi.org/10.1056/NEJM200011093431901) and Felsberg et al. (Clin Cancer Res 15(21):6683–6693, 2009. https://doi.org/10.1158/1078-0432.CCR-08-2801) resulted in partially discordant results in 22 tumors (27.5%). Local deep bisulfite sequencing (LDBS) revealed that CpGs located in exon 1 are suited best to discriminate methylated from unmethylated samples. Based on LDBS data, we propose an optimized MSP primer pair with 83% and 85% concordance to pyrosequencing and LDBS data. A hitherto neglected region upstream of the TSS, with an overall higher methylation compared to exon 1 and intron 1 of MGMT, is also able to discriminate the methylation status.ConclusionOur integrated analysis allows to evaluate and redefine co-methylation domains within the MGMT promoter and to rationalize the practical impact on assays used in daily routine diagnostics.

Identification of an m6A RNA Methylation Regulator Risk Score Model for Prediction of Clinical Prognosis in Astrocytoma.

Astrocytoma (AS) is the most ubiquitous primary malignancy of the central nervous system (CNS). The vital involvement of the N6-methyladenosine (m6A) RNA modification in the growth of multiple human tumors is known. This study entailed probing m6A regulators with AS prognosis to construct a risk prediction model (RS) for potential clinical use. A total of 579 AS patients' (of the Chinese Glioma Genome Atlas,CGGA) data and the expression of 12 published m6A-related genes were included in this study. Cox and selection operator (LASSO) regression analyses for independent prognostic factors and multifactor Cox analysis established an R.S. model to predict the AS patient prognosis. This was subject to verification employing 331 samples from the TCGA data set followed by gene ontology and pathway enrichment study with gene set enrichment analysis (GSEA). The R.S. constructed with three m6A genes inclusive of WTAP, RBM15, and YTHDF2 emerged as independent prognostic factors in AS patients with vital involvement in the advancement and development of the malignancy. In a nutshell, this work reported an m6A-related gene risk model to predict the prognosis of AS patients to pave the way for discerning diagnostic and prognostic biomarkers. Further corroboration employing relevant wet-lab assays of this model is warranted.

A Population-Based Study of Treatment and Survival in Older Glioma Patients

BackgroundPopulation-based analyses of patterns of care and survival of older patients diagnosed with grade II-III oligodendroglioma (OLI) or astrocytoma (AST) can aid clinicians in their understanding and care of these patients.MethodsWe identified patients diagnosed between 2006 and 2015 with primary glioma diagnoses (OLI or AST) who were older than 65 years using the latest release of the Surveillance, Epidemiology, and End Results-Medicare–linked database. Medicare claims were used to identify cancer treatments (surgery, chemotherapy, and radiation therapy) from 2006 to 2016. Kaplan-Meier methodology was used to describe overall survival (OS). Cox proportional hazards regression was used to associate variables of interest, including treatments in a time-dependent manner, with OS. Hazard ratios (HRs) and 95% confidence intervals (CIs) from multivariable, cause-specific competing risk models identified associations with treatments. All statistical tests were 2-sided.ResultsWe identified 1291 patients comprising 158 with OLI, 1043 with AST, and 90 with mixed histologies. Median OS was 6.5 (95% CI = 6.1 to 7.3) months for the overall cohort, 22.6 (95% CI = 13.9 to 33.1) months for OLI, and 5.8 (95% CI = 5.3 to 6.4) months for AST. Patients who received surgery and patients who received both chemotherapy and radiation therapy in combination experienced better OS (HR = 0.87, 95% CI = 0.79 to 0.96, and HR = 0.58, 95% CI = 0.35 to 0.96, respectively). Over the time frame studied, there was a 4.0% increase per year in prescription of chemotherapy (P = .03) and a 2.0% improvement in OS for each calendar year (P = .003).ConclusionsWe provide population-based evidence that patients older than 65 years with grade II-III glioma have experienced increased chemotherapy use as well as improvement in survival over time.