methylguanine-DNA Methyltransferase Promoter Methylation Research Articles

MGMT promoter methylation prediction based on multiparametric MRI via vision graph neural network.

Glioblastoma (GBM) is aggressive and malignant. The methylation status of the -methylguanine-DNA methyltransferase (MGMT) promoter in GBM tissue is considered an important biomarker for developing the most effective treatment plan. Although the standard method for assessing the MGMT promoter methylation status is via bisulfite modification and deoxyribonucleic acid (DNA) sequencing of biopsy or surgical specimens, a secondary automated method based on medical imaging may improve the efficiency and accuracy of those tests. We propose a deep vision graph neural network (ViG) using multiparametric magnetic resonance imaging (MRI) to predict the MGMT promoter methylation status noninvasively. Our model was compared to the RSNA radiogenomic classification winners. The dataset includes 583 usable patient cases. Combinations of MRI sequences were compared. Our multi-sequence fusion strategy was compared with those using single MR sequences. Our best model [Fluid Attenuated Inversion Recovery (FLAIR), T1-weighted pre-contrast (T1w), T2-weighted (T2)] outperformed the winning models with a test area under the curve (AUC) of 0.628, an accuracy of 0.632, a precision of 0.646, a recall of 0.677, a specificity of 0.581, and an F1 score of 0.661. Compared to the winning models with single MR sequences, our ViG utilizing fused-MRI showed a significant improvement statistically in AUC scores, which are FLAIR (), T1w (), T1wCE (), and T2 (). Our model is superior to challenge champions. A graph representation of the medical images enabled good handling of complexity and irregularity. Our work provides an automatic secondary check pipeline to ensure the correctness of MGMT methylation status prediction.

Proteomic and metabolomic analyses illustrate the mechanisms of expression of the O6 -methylguanine-DNA methyltransferase gene in glioblastoma.

Glioblastoma (GBM) has been reported to be the most common high-grade primary malignant brain tumor in clinical practice and has a poor prognosis. O6 -methylguanine-DNA methyltransferase (MGMT) promoter methylation has been related to prolonged overall survival (OS) in GBM patients after temozolomide treatment. Proteomics and metabolomics were combined to explore the dysregulated metabolites and possible protein expression alterations in white matter (control group), MGMT promoter unmethylated GBM (GBM group) or MGMT promoter methylation positive GBM (MGMT group). In total, 2745 upregulated and 969 downregulated proteins were identified in the GBM group compared to the control group, and 131 upregulated and 299 downregulated proteins were identified in the MGMT group compared to the GBM group. Furthermore, 131 upregulated and 299 downregulated metabolites were identified in the GBM group compared to the control group, and 187 upregulated and 147 downregulated metabolites were identified in the MGMT group compared to the GBM group. The results showed that 94 upregulated and 19 downregulated proteins and 20 upregulated and 16 downregulated metabolites in the MGMT group were associated with DNA repair. KEGG pathway enrichment analysis illustrated that the dysregulated proteins and metabolites were involved in multiple metabolic pathways, including the synthesis and degradation of ketone bodies, amino sugar and nucleotide sugar metabolism. Moreover, integrated metabolomics and proteomics analysis was performed, and six key proteins were identified in the MGMT group and GBM group. Three key pathways were recognized as potential biomarkers for recognizing MGMT promoter unmethylated GBM and MGMT promoter methylation positive GBM from GBM patient samples, with areas under the curve of 0.7895, 0.7326 and 0.7026, respectively. This study provides novel mechanisms to understand methylation in GBM and identifies some biomarkers for the prognosis of two different GBM types, MGMT promoter unmethylated or methylated GBM, by using metabolomics and proteomics analyses.

Brain Tumor Radiogenomic Classification of O6-Methylguanine-DNA Methyltransferase Promoter Methylation in Malignant Gliomas-Based Transfer Learning.

Artificial Intelligence (AI) is the subject of a challenge and attention in the field of oncology and raises many promises for preventive diagnosis, but also fears, some of which are based on highly speculative visions for the classification and detection of tumors. A brain tumor that is malignant is a life-threatening disorder. Glioblastoma is the most prevalent kind of adult brain cancer and the 1 with the poorest prognosis, with a median survival time of less than a year. The presence of O6 -methylguanine-DNA methyltransferase (MGMT) promoter methylation, a particular genetic sequence seen in tumors, has been proven to be a positive prognostic indicator and a significant predictor of recurrence.This strong revival of interest in AI is modeled in particular to major technological advances which have significantly increased the performance of the predicted model for medical decision support. Establishing reliable forecasts remains a significant challenge for electronic health records (EHRs). By enhancing clinical practice, precision medicine promises to improve healthcare delivery. The goal is to produce improved prognosis, diagnosis, and therapy through evidence-based sub stratification of patients, transforming established clinical pathways to optimize care for each patient's individual requirements. The abundance of today's healthcare data, dubbed "big data," provides great resources for new knowledge discovery, potentially advancing precision treatment. The latter necessitates multidisciplinary initiatives that will use the knowledge, skills, and medical data of newly established organizations with diverse backgrounds and expertise.The aim of this paper is to use magnetic resonance imaging (MRI) images to train and evaluate your model to detect the presence of MGMT promoter methylation in this competition to predict the genetic subtype of glioblastoma based transfer learning. Our objective is to emphasize the basic problems in the developing disciplines of radiomics and radiogenomics, as well as to illustrate the computational challenges from the perspective of big data analytics.

Identification of MGMT Downregulation Induced by miRNA in Glioblastoma and Possible Effect on Temozolomide Sensitivity.

Glioblastoma multiforme (GBM) remains one of the tumors with the worst prognosis. In recent years, a better overall survival (OS) has been described in cases subjected to Gross Total Resection (GTR) that were presenting hypermethylation of Methylguanine-DNA methyltransferase (MGMT) promoter. Recently, also the expression of specific miRNAs involved in MGMT silencing has been related to survival. In this study, we evaluate MGMT expression by immunohistochemistry (IHC), MGMT promoter methylation and miRNA expression in 112 GBMs and correlate the data to patients' clinical outcomes. Statistical analyses demonstrate a significant association between positive MGMT IHC and the expression of miR-181c, miR-195, miR-648 and miR-767.3p between unmethylated cases and the low expression of miR-181d and miR-648 and between methylated cases and the low expression of miR-196b. Addressing the concerns of clinical associations, a better OS has been described in presence of negative MGMT IHC, in methylated patients and in the cases with miR-21, miR-196b overexpression or miR-767.3 downregulation. In addition, a better progression-free survival (PFS) is associated with MGMT methylation and GTR but not with MGMT IHC and miRNA expression. In conclusion, our data reinforce the clinical relevance of miRNA expression as an additional marker to predict efficacy of chemoradiation in GBM.

A Multimodal Knowledge-Based Deep Learning Approach for MGMT Promoter Methylation Identification.

Glioblastoma Multiforme (GBM) is considered one of the most aggressive malignant tumors, characterized by a tremendously low survival rate. Despite alkylating chemotherapy being typically adopted to fight this tumor, it is known that O(6)-methylguanine-DNA methyltransferase (MGMT) enzyme repair abilities can antagonize the cytotoxic effects of alkylating agents, strongly limiting tumor cell destruction. However, it has been observed that MGMT promoter regions may be subject to methylation, a biological process preventing MGMT enzymes from removing the alkyl agents. As a consequence, the presence of the methylation process in GBM patients can be considered a predictive biomarker of response to therapy and a prognosis factor. Unfortunately, identifying signs of methylation is a non-trivial matter, often requiring expensive, time-consuming, and invasive procedures. In this work, we propose to face MGMT promoter methylation identification analyzing Magnetic Resonance Imaging (MRI) data using a Deep Learning (DL) based approach. In particular, we propose a Convolutional Neural Network (CNN) operating on suspicious regions on the FLAIR series, pre-selected through an unsupervised Knowledge-Based filter leveraging both FLAIR and T1-weighted series. The experiments, run on two different publicly available datasets, show that the proposed approach can obtain results comparable to (and in some cases better than) the considered competitor approach while consisting of less than 0.29% of its parameters. Finally, we perform an eXplainable AI (XAI) analysis to take a little step further toward the clinical usability of a DL-based approach for MGMT promoter detection in brain MRI.

Immunohistochemical Expression of PD-L1 and IDH1 with Detection of MGMT Promoter Methylation in Astrocytoma

Programmed death ligand 1 (PD-L1) expression was suggested as a poor prognostic predictor for glioblastoma. While isocitrate dehydrogenase (IDH) has been linked to enhanced overall survival in glioma cells. In glioblastoma patients receiving treatment with alkylating drugs, the methylguanine-DNA methyltransferase (MGMT) promoter's methylation status has been discovered as a potent and distinct predictor of good survival. In this study, we aimed to investigate the expression rate of PD-L1, IDH1, and MGMT methylation in patients with different grades of astrocytoma. The present retrospective study retrieved the data and archived paraffin blocks of 60 cases of astrocytoma. Immunohistochemical evaluation was done to assess the expressions of PD-L1 and IDH1, Methylation-specific-PCR was used to investigate the MGMT promoter. This study included astrocytoma grade II 18% (11/60), grade III 22% (13/60), grade IV 60% (36 cases). PD-L1 expression was detected in 82% of all studied cases (49/60) while IDH1 mutant astrocytoma were 73% (44/60) & methylation was reported in 58.3% (35 cases). High grade astrocytoma showed highrer expression of PD-L1 & IDH1 but with insignificant correlation (p=0.989). There is a relatively high expression of PD-L1 and IDH1 in patients with astrocytoma. More than half of the patients presented with MGMT promoter methylation. Further studies with larger sample size are required to investigate the association between these biomarkers and characteristics of patients with astrocytoma.

RTID-05. TRIAL IN PROGRESS: DOSE-FINDING STUDY AND EVALUATION OF [177LU]LU-DOTA-TATE IN COMBINATION WITH STANDARD OF CARE IN NEWLY DIAGNOSED GLIOBLASTOMA AND AS A SINGLE AGENT IN RECURRENT GLIOBLASTOMA

Abstract Patients with glioblastoma have a poor prognosis despite extensive efforts to develop new treatments. Standard of care for newly diagnosed patients is surgery followed by radiotherapy plus temozolomide. However, temozolomide only provides a clinical benefit to patients who have glioblastomas with a methylated O(6)-methylguanine-DNA methyltransferase (MGMT) gene promotor. Disease recurrence is inevitable and subsequent treatments have poor outcomes due to limited efficacy and a lack of established therapeutic regimens. [68Ga]Ga-DOTA-TATE is a radioligand imaging agent that selectively binds to somatostatin receptors (SSTRs) and is used with positron emission tomography (PET) for the molecular imaging of SSTR-positive neuroendocrine tumors. Glioblastoma tumoral PET scans have shown moderate uptake of [68Ga]Ga-DOTA-TATE. The radioligand therapy [177Lu]Lu-DOTA-TATE has the same SSTR-targeted ligand and demonstrated promising clinical activity in a pilot study in patients with Grade III/IV gliomas. This Phase 1b open-label dose-finding study (NCT05109728) will determine the recommended [177Lu]Lu-DOTA-TATE dose in three different groups of glioblastoma (newly diagnosed with methylated MGMT promoter [group 1], newly diagnosed with unmethylated MGMT promoter [group 2], and recurrent disease [group 3]). All participants will be scanned with [68Ga]Ga-DOTA-TATE imaging during screening and, for each group, approximately 15 participants will be enrolled in consecutive cohorts of 3–6 participants. All participants will receive up to 6 administrations of [177Lu]Lu-DOTA-TATE (initial dose 150 mCi with 3 provisional dose levels up to 250 mCi) using the Bayesian Optimal Interval design. Group 1 will receive [177Lu]Lu-DOTA-TATE every 4 weeks with concomitant radiotherapy and temozolomide, followed by temozolomide maintenance. Group 2 will receive [177Lu]Lu-DOTA-TATE every 4 weeks for 3 doses with radiotherapy then every 3 weeks as a single agent. Group 3 will receive [177Lu]Lu-DOTA-TATE only, every 3 weeks. The primary endpoint is incidence of dose limiting toxicity. Secondary endpoints include overall objective status (modified RANO criteria), progression free survival, overall survival and safety.

140P Retrospective review of actionable IDH mutations and MGMT promoter methylation among CNS tumors

In the revised World Health Organization (WHO) Classification of Tumors of the Central Nervous System, molecular genetic alterations have been incorporated to the classic histology of primary brain tumors (PBT), including isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) mutations and methylation of the O6 -methylguanine-DNA methyltransferase promoter (MGMT). The IDH mutation is associated with a better prognosis in patients with glioma, independently of histological parameters and tumor grade. MGMT methylation silences the MGMT gene and reduces the ability of tumor cells to repair damage caused by temozolomide and other alkylating agents.

Quantitative Analysis of the MGMT Methylation Status of Glioblastomas in Light of the 2021 WHO Classification.

Simple SummaryThe status of a DNA repair protein called MGMT is a prognostic marker in patients with glioblastomas, the most frequent malignant brain tumor. Epigenetic silencing of this gene predicts increased sensitivity to chemotherapy. Silencing is assessed by analyzing modifications, so-called methylation, of a certain gene region. Whereas most studies report such information only in a qualitative manner, quantitative testing might provide additional information. The aim of our study was to determine a quantitative threshold for better survival among patients with glioblastomas. Among 321 patients suffering from glioblastoma, we found better survival in patients with glioblastomas that have ≥16% methylation of a particular region of the MGMT gene. Above 16% methylation, we found no additional benefit with increasing degree of methylation. We suggest using this threshold for selection in clinical trials and for patient counseling.Background: Glioblastomas with methylation of the promoter region of the O(6)-methylguanine-DNA methyltransferase (MGMT) gene exhibit increased sensitivity to alkylating chemotherapy. Quantitative assessment of the MGMT promoter methylation status might provide additional prognostic information. The aim of our study was to determine a quantitative methylation threshold for better survival among patients with glioblastomas. Methods: We included consecutive patients ≥18 years treated at our department between 11/2010 and 08/2018 for a glioblastoma, IDH wildtype, undergoing quantitative MGMT promoter methylation analysis. The primary endpoint was overall survival. Results: A total of 321 patients were included. Median overall survival was 12.6 months. Kaplan–Meier and adjusted Cox regression analysis showed better survival for the groups with 16–30%, 31–60%, and 61–100% methylation. In contrast, survival in the group with 1–15% methylation was similar to those with unmethylated promoter regions. A secondary analysis confirmed this threshold. Conclusions: Better survival is observed in patients with glioblastomas with ≥16% methylation of the MGMT promoter region than with <16% methylation. Survival with tumors with 1–15% methylation is similar to with unmethylated tumors. Above 16% methylation, we found no additional benefit with increasing methylation.

Monocentric evaluation of Ki-67 labeling index in combination with a modified RPA score as a prognostic factor for survival in IDH-wildtype glioblastoma patients treated with radiochemotherapy

PurposeThe prognosis for glioblastoma patients remains dismal despite intensive research on better treatment options. Molecular and immunohistochemical markers are increasingly being investigated as understanding of their role in disease progression grows. O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation has been shown to have prognostic and therapeutic relevance for glioblastoma patients. Other markers implicated in tumor formation and/or malignancy are p53, Alpha thalassemia/mental retardation syndrome X-linked (ATRX), Epidermal Growth Factor Receptor splice variant III (EGFRvIII), and Ki-67, with loss of nuclear ATRX expression and lower Ki-67 index being associated with prolonged survival. For p53 and EGFRvIII the data are contradictory. Our aim was to investigate the markers mentioned above regarding progression-free (PFS) and overall survival (OS) to evaluate their viability as independent prognostic markers for our patient collective.MethodsIn this retrospective study, we collected data on patients undergoing radiotherapy due to isocitrate dehydrogenase (IDH) wildtype glioblastoma at a single university hospital between 2014 and 2020.ResultsOur findings confirm Ki-67 labeling index ≤ 20% as an independent prognostic factor for prolonged PFS as well as MGMT promoter methylation for both prolonged PFS and OS, in consideration of age and Eastern Cooperative Oncology Group (ECOG) status, chemotherapy treatment, and total radiation dose for PFS as well as additionally sex, resection status, and receipt of treatment for progression or recurrence for OS. Additionally, Ki-67 labeling index ≤ 20% showed a significant correlation with prolonged OS in univariate analysis. Modification of the recursive partitioning analysis (RPA) score to include Ki-67 labeling index resulted in a classification with the possible ability to distinguish long-term-survivors from patients with unfavorable prognosis.ConclusionMGMT promoter methylation and Ki-67 labeling index were independent predictors of survival in our collective. We see further studies pooling patient collectives to reach larger patient numbers concerning Ki-67 labeling index as being warranted.

Associations among smoking, IDH mutations, MGMT promoter methylation, and grading in glioma: a cross-sectional study

Background Several molecular markers have important roles in glioma management. Mutations in the isocitrate dehydrogenase (IDH) gene are associated with the grading and prognosis of glioma. Methylation in the promoter region of the O (6)-methylguanine-DNA methyltransferase (MGMT) gene is an important determinant of glioma sensitivity to alkylating agents. Studies in various cancers indicated that IDH1 mutations and MGMT promoter methylations were associated with smoking habits. However, these associations in gliomas are still unclear. Accordingly, this study aimed to examine the association among smoking, IDH1 mutations, MGMT promoter methylation, and grading in glioma patients. Methods Patients were recruited from Dr. Sardjito General Hospital (a referral hospital in Yogyakarta and Central Java region) and its network hospitals. Genomic DNA was extracted from formalin-fixed paraffin-embedded samples or fresh glioma tissues. Identification of IDH1 mutation was performed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) or DNA sequencing. Methylation-specific real-time PCR was performed to identify MGMT promoter methylation status. Smoking status was obtained by history taken from the patient or family members. Results In total, 122 patients were included in this study. As many as 35 patients (28.7%) had a smoking history. Most smokers (57.1%) smoke less than ten cigarettes per day. However, most of them (68.8%) have been smoking for more than 20 years. Smoking patients have a significantly higher proportion of high-grade glioma than non-smokers (80% vs. 55.2%, p=0.01). Among 122 patients, 24 (19.7%) of them carried IDH1 mutation. Smoking patients have a significantly higher proportion of IDH1 mutation compared with non-smokers (31.4% vs. 14.9%, p&lt;0.001). No significant association was found between intensity and duration of smoking with IDH1 mutations and glioma grading. No significant association was found between smoking and MGMT promoter methylation. Conclusions In glioma patients, smoking is associated with IDH1 mutations and grading but not with MGMT promoter methylation.

Diffuse Midline Gliomas With Histone H3 K27M Mutation in Adults and Children: A Retrospective Series of 164 Cases.

Diffuse midline glioma, H3 K27M-mutant (H3 K27M-mt DMG), is a rare and highly aggressive tumor that is more common in children than in adults. Few studies have compared the differences between pediatric and adult patients with this rare tumor. We here report our retrospective study of 94 adult and 70 pediatric cases of diffuse midline glioma. Surgical tumor samples were analyzed by routine histopathology and immunohistochemistry for H3 K27M, IDH1 R132H, ATRX, p53, OLIG2, glial fibrillary acidic protein, and Ki-67; Sanger sequencing for hot mutation spots in genes including H3F3A, HIST1H3B, IDH1, IDH2, TERT, and BRAF; and methylation-specific polymerase chain reaction for O 6 -methylguanine DNA methyltransferase promoter methylation. The most frequent anatomic locations in adult and pediatric patients were the thalamus and brainstem, respectively. Molecular profiling revealed higher frequencies of ATRX loss and H3.3 mutation in adult than in pediatric H3 K27M-mt DMGs. TERT promoter mutations and O 6 -methylguanine DNA methyltransferase promoter methylation were not detected in pediatric patients but were present in a few adult patients. During the follow-up period, 93/122 patients (70.1%) died from the disease, with a median survival time of 10.5 months (range: 1 to 104 mo). Kaplan-Meier analyses demonstrated that the prognosis was better for adult patients than the pediatric cohort (P=0.0003). Multivariate analyses indicated that patient age, primary tumor size, status of ATRX expression, and Ki-67 index were independent prognosticators. The present study showed that there were differences between adult and pediatric H3 K27M-mt DMGs in terms of the anatomic location of tumor, molecular changes, and prognosis.

RADT-15. FIRST EXPERIENCE WITH MAXIMAL SAFE RESECTION AND GAMMATILE BRACHYTHERAPY AS TREATMENT FOR RECURRENT GLIOBLASTOMA

Abstract INTRODUCTION Gammatile (GT) is a recently FDA-cleared brachytherapy platform with 131Cs seeds imbedded into a resorbable collagen carrier for surgically targeted radiation delivery. We report the first experience for recurrent glioblastoma patients who underwent GT treatment following surgical resection. METHODS Twenty-two consecutive patients with 23 isocitrate dehydrogenase (IDH) wild-type glioblastomas (14 second; eight third recurrence) who underwent intra-operative MRI/5-ALA guided maximal safe resection followed by GT placement were prospectively followed. There were 6 methylguanine-DNA-methyltransferase promoter methylated (MGMTm) and 17 unmethylated (MGMTu) glioblastomas. RESULTS The median hospital stay was one day (range:1-15 days). There was one 30-day readmission (4.5%) for a cerebrospinal fluid leak from the incision site, which resolved with lumbar drainage. There were no other wound complications. One patient (4.5%) suffered new post-operative seizure. Eight patients experienced worsened neurological deficit (8/22 or 36%). While all deficits improved by the 30-day follow-up, 7 of these 8 patients suffered KPS decline due to persistent deficits. There was one 30-day mortality (4.5%) from intracranial hemorrhage secondary to heparinization for an ischemic limb. The median follow-up after GT placement for the remaining 21 patients was 296 days (range:111-931 days). Six months local control (LC) was achieved in ~75% of the patients irrespective of MGMT status. Median overall survival (OS) was 715 days for the MGMTu patients, and not reached (&amp;gt;1000 days) for MGMTm patients. These outcomes compared favorably to the published literature (LC: 3-49%; OS MGMTu: 135-285 days; OS MGMTm: 174-564 days) and an age, KPS, extent of resection matched glioblastoma cohort who underwent maximal safe resection without GT at our institution (LC: 52%; OS MGMTu: 462 days; OS MGMTm: 821 days; p=0.0089 and p=0.0271, respectively when compared to the GT treated patients). CONCLUSION This clinical experience supports the safety and efficacy of GT brachytherapy as a treatment option for recurrent glioblastomas.

CTNI-21. PHASE 2 STUDY OF VAL-083 AND RADIOTHERAPY IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GBM

Abstract Approximately 60% of glioblastoma multiforme (GBM) patients possess an unmethylated methylguanine DNA-methyltransferase (MGMT) gene promoter, which confers a limited clinical response to standard-of-care treatment with temozolomide (TMZ), resulting in shorter median survival when compared to patients with a methylated MGMT promoter. VAL-083 is a novel bi-functional DNA targeting agent that induces interstrand DNA cross-links at N7-guanine, leading to DNA double-strand breaks and ultimately cell death. VAL-083 circumvents MGMT-mediated TMZ resistance in vitro and in vivo. A Phase 2 study has been conducted to evaluate efficacy and safety of VAL-083 when administered concurrently with radiation therapy (RT) in newly diagnosed MGMT unmethylated GBM. The study was conducted in 2 stages: Stage 1 was a dose-escalation phase to confirm the dose of VAL-083 in this setting. Patients received VAL-083 at 20, 30, or 40 mg/m2/day x 3 days every 21 days along with standard radiation treatment (RT) (2 Gy/day, 5 days/week for 6 weeks). At the end of this stage, 30 mg/m2/day of VAL-083 in combination with RT was generally safe and well-tolerated. Stage 2 was an expansion phase to enroll up to 20 additional patients at the 30 mg/m2/day of VAL-083 in combination with RT. All patients have been enrolled, with a total of 29 patients in the study, and 25 patients receiving 30 mg/m2/day VAL-083. All 29 patients have completed treatment and patients are in the follow-up phase of the study. Consistent with our prior experience, myelosuppression was the most common adverse event. As of March 2021, 22/29 (75.9%) subjects had disease progression. The median progression free survival for all patients enrolled was 9.3 (95%CI: 6.4-12.0) months. Sixteen (16/29; 55.2%) patients had died, and median overall survival for all patients enrolled was 19.6 (95%CI: 14.0-22.4) months. Further safety and efficacy updates will be presented at the meeting. Clinicaltrials.gov identifier: NCT03050736.

P14.65 Survival in a consecutive series of 467 glioblastoma patients: impact of prognostic factors and recurrent treatment at two independent institutions

Abstract BACKGROUND Glioblastoma (GBM) is an aggressive primary brain tumor with median overall survival (OS) of less than one year in unselected adult patients. There is no standard therapy at recurrence. We aimed to evaluate OS in a consecutive series of GBM patients from Norway’s two largest regional health authorities, compare the effect of physicians’ choice of antineoplastic treatment upon recurrence and identify prognostic and predictive factors. MATERIAL AND METHODS Clinicopathological data from n=467 patients with histologically confirmed GBM diagnosed and treated at Haukeland and Oslo university hospitals from January 2015 to December 2017 was retrospectively collected. Data included tumor location, methylation status of the methylguanine-DNA methyltransferase (MGMT) promoter and mutation of the isocitrate dehydrogenase (IDH) genes, patient age and sex, extent of tumor resection at primary diagnosis, and treatment at first, second and third tumor recurrences. Cox-proportional hazards regression with pairwise analyses adjusted for multiple testing with Scheffé’s post-hoc test were used to adjust effect of multiple risk factors on mortality. RESULTS Median OS was 12.1 months and 21.4 % and 6.8 % of patients were alive at 2 and 5 years, respectively. Treatment at recurrence varied between institutions but did not impact OS (p=0.201). Median time to progression was 8.2 months. Age, MGMT promoter methylation, tumor location and extent of tumor resection were all independent prognostic factors for OS. Patients receiving radiotherapy to 60 Gray with concomitant and adjuvant temozolomide at primary diagnosis had best outcome with median OS of 16.1 months and 9.3% were alive at 5 years. At first recurrence patients eligible for gammaknife/stereotactic radiosurgery (GK/SRS) or surgery, alone or combined with chemotherapy, had superior survival compared to chemotherapy alone (p&amp;lt;0.0001 and p=0.014, respectively). On Scheffé’s post-hoc analyses only GK/SRS was superior to chemotherapy (p=0.01). At second and third recurrence none of the antineoplastic strategies came across as superior or inferior to each other using Cox. On Scheffé’s post-hoc analyses chemotherapy alone and combined with bevacizumab were superior at second recurrence (p=0.008 and p=0.042, respectively) and chemotherapy combined with bevacizumab was superior at third recurrence (p=0.043), compared to no antineoplastic treatment. Our retrospective study is limited by small sample sizes and heterogeneous treatment groups, especially at second and third recurrences, as well as patient selection. CONCLUSION Recurrence treatment differed between the two institutions but there was no difference in OS. Our findings underline the lack of standard therapy upon GBM recurrence and the urgent need for novel therapeutic strategies.

Automated machine learning to predict the co-occurrence of isocitrate dehydrogenase mutations and O6 -methylguanine-DNA methyltransferase promoter methylation in patients with gliomas.

Combining isocitrate dehydrogenase mutation (IDHmut) with O6 -methylguanine-DNA methyltransferase promoter methylation (MGMTmet) has been identified as a critical prognostic molecular marker for gliomas. The aim of this study was to determine the ability of glioma radiomics features from magnetic resonance imaging (MRI) to predict the co-occurrence of IDHmut and MGMTmet by applying the tree-based pipeline optimization tool (TPOT), an automated machine learning (autoML) approach. This was a retrospective study, in which 162 patients with gliomas were evaluated, including 58 patients with co-occurrence of IDHmut and MGMTmet and 104 patients with other status comprising: IDH wildtype and MGMT unmethylated (n=67), IDH wildtype and MGMTmet (n=36), and IDHmut and MGMT unmethylated (n=1). Three-dimensional (3D) T1-weighted images, gadolinium-enhanced 3D T1-weighted images (Gd-3DT1WI), T2-weighted images, and fluid-attenuated inversion recovery (FLAIR) images acquired at 3.0 T were used. Radiomics features were extracted from FLAIR and Gd-3DT1WI images. The TPOT was employed to generate the best machine learning pipeline, which contains both feature selector and classifier, based on input feature sets. A 4-fold cross-validation was used to evaluate the performance of automatically generated models. For each iteration, the training set included 121 subjects, while the test set included 41 subjects. Student's t-test or a chi-square test was applied on different clinical characteristics between two groups. Sensitivity, specificity, accuracy, kappa score, and AUC were used to evaluate the performance of TPOT-generated models. Finally, we compared the above metrics of TPOT-generated models to identify the best-performing model. Patients' ages and grades between two groups were significantly different (p=0.002 and p=0.000, respectively). The 4-fold cross-validation showed that gradient boosting classifier trained on shape and textual features from the Laplacian-of-Gaussian-filtered Gd-3DT1 achieved the best performance (average sensitivity=81.1%, average specificity=94%, average accuracy=89.4%, average kappa score=0.76, average AUC=0.951). Using autoML based on radiomics features from MRI, a high discriminatory accuracy was achieved for predicting co-occurrence of IDHmut and MGMTmet in gliomas. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 3.

CTNI-76. PHASE 2 CLINICAL TRIAL OF VAL-083 IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GBM

Abstract Approximately 60% of glioblastoma multiforme (GBM) patients possess an unmethylated methylguanine DNA-methyltransferase (MGMT) promoter region, which confers a limited response to standard-of-care treatment with temozolomide (TMZ), resulting in shorter median survival when compared to patients with methylated MGMT promoter. VAL-083 is a novel bi-functional DNA targeting agent that induces inter-strand cross-links at N7-guanine, leading to DNA double-strand breaks and ultimately cell death. VAL-083 circumvents MGMT-mediated TMZ resistance in vitro and in vivo. A Phase 2 study has been initiated for VAL-083 in newly diagnosed MGMT unmethylated GBM. The study has 2 stages: Stage 1 is a dose-escalation safety and tolerability phase to confirm the phase 2 dose of VAL-083 when administered concurrently with radiation therapy (RT). Patients received VAL-083 at 20, 30, or 40 mg/m2/day x 3 days every 21 days along with standard radiation treatment (RT) (2 Gy/day, 5 days/week). The dose escalation stage is complete, and 30 mg/m2/day of VAL-083 in combination with RT was generally safe and well-tolerated. Stage 2 comprises an expansion phase to enroll up to 20 additional patients at the 30 mg/m2/day of VAL-083 in combination with RT. As of June 2, 2020, all patients have been enrolled, with a total of 29 patients in the study, and 25 patients receiving 30 mg/m2/day VAL-083. Of the 29 patients enrolled, 27 have completed their prospectively planned MRI scans and had their initial assessment for tumor response. Two additional patients died prior to their post-cycle 3 MRI. Consistent with our prior experience, myelosuppression was the most common adverse event. Three patients have experienced dose-limiting toxicities - one (1/3; 33%) at the 40 mg/m2/day and two (2/25; 8%) at the 30 mg/m2/day dose. Further safety and efficacy updates will be presented at the meeting. Clinicaltrials.gov identifier: NCT03050736.

Glioblastoma Recurrence and the Role of O6-Methylguanine-DNA Methyltransferase Promoter Methylation.

Tumor recurrence in glioblastoma multiforme (GBM) is often attributed to acquired resistance to the standard chemotherapeutic agent, temozolomide (TMZ). Promoter methylation of the DNA repair gene MGMT (O6-methylguanine-DNA methyltransferase) has been associated with sensitivity to TMZ, whereas increased expression of MGMT has been associated with TMZ resistance. Clinical studies have observed a downward shift in MGMT methylation percentage from primary to recurrent stage tumors; however, the evolutionary processes that drive this shift and more generally the emergence and growth of TMZ-resistant tumor subpopulations are still poorly understood. Here, we develop a mathematical model, parameterized using clinical and experimental data, to investigate the role of MGMT methylation in TMZ resistance during the standard treatment regimen for GBM-surgery, chemotherapy, and radiation. We first found that the observed downward shift in MGMT promoter methylation status between detection and recurrence cannot be explained solely by evolutionary selection. Next, our model suggests that TMZ has an inhibitory effect on maintenance methylation of MGMT after cell division. Finally, incorporating this inhibitory effect, we study the optimal number of TMZ doses per adjuvant cycle for patients with GBM with high and low levels of MGMT methylation at diagnosis.

CBMT-22. REVERSING THE WARBURG EFFECT BY TARGETING NICOTINAMIDE PHOSPHORIBOSYLTRANSFERASE (NAMPT), THE RATE-LIMITING ENZYME OF NAD+ SALVAGE PATHWAY INCREASES, CHEMOSENSITIVITY TO TEMOZOLOMIDE IN GLIOMA CELLS

Abstract BACKGROUND Glioma cells metabolize glucose primarily through incomplete, non-oxidative glycolysis even in the presence of oxygen (the Warburg effect) which provides a constant supply of substrate for proliferation and generates an acidic environment that favors invasion and immunosuppression. NAMPT, the rate-limiting enzyme of the NAD+ salvage pathway, regulates key metabolic processes preferentially used in glioma energy metabolism. Inhibition of NAMPT could have global impact on glioma cell metabolism and could be a promising strategy for glioma therapy. This study examined the effect of NAMPT inhibition using KPT-9274 and FK866 (NAMPTi) on glycolysis and glioma cell metabolism. METHODS Metabolic changes related to NAMPT inhibition were examined in glioma cell lines and patient derived glioma stem-like cells (GSC). Mass spectrometry was used for metabolic profiles and the generated data was annotated by comparison against an extensive metabolite library to identify relevant metabolites. The Agilent Seahorse assay was utilized to determine treatment-related changes in glycolysis. RESULTS NAMPT inhibition caused NAD, NADH, NADP, NADPH, and ATP depletion in glioma cells. Global metabolomics results showed an accumulation of GMP, IMP, AMP and myo-inositol indicating reprogramming of glioma cell metabolism for de novo purine biosynthesis. Additionally, an accumulation of glucose- and fructose-1,6 bisphosphate in NAMPTi treated cells indicated dysfunctional glycolysis. This was confirmed by the Agilent glycolysis stress test by which NAMPTi-treated glioma cells showed a reduction in glycolysis, glycolytic capacity and reserves. NAMPTi treated cells showed downregulation of LDHA due to NAD depletion. Further, downregulation of LDHA enhanced the chemosensitivity of glioma cells to temozolomide. CONCLUSIONS NAMPTi cause profound disruption of glycolysis, reduced glycolytic capacity and glycolytic reserve in gliomas and GSCs irrespective of O[6]-methylguanine-DNA methyltransferase promoter methylation or IDH1 status. Targeting NAMPT to disrupt the Warburg effect is a novel strategy for developing effective therapies against glioma to overcome heterogeneity.

Risks and Benefits of Glioblastoma Resection in Older Adults: A Retrospective Austrian Multicenter Study

To assess the prognostic profile, clinical outcome, treatment-associated morbidity, and treatment burden of elderly patients with glioblastoma (GBM) undergoing microsurgical tumor resection as part of contemporary treatment algorithms. We retrospectively identified patients with GBM ≥65 years of age who were treated by resection at 2 neuro-oncology centers. Survival was assessed by Kaplan-Meier analyses; log-rank tests identified prognostic factors. The study population included 160 patients (mean age, 73.1 ± 5.1 years), and the median contrast-enhancing tumor volume was 31.0 cm3. Biomarker analyses revealed O(6)-methylguanine-DNA methyltransferase-promoter methylation in 62.7% and wild-type isocitrate dehydrogenase in 97.5% of tumors. The median extent of resection (EOR) was 92.3%, surgical complications were noted in 10.0% of patients, and the median postoperative hospitalization period was 8 days. Most patients (60.0%) received adjuvant radio-/chemotherapy. The overall treatment-associated morbidity was 30.6%. The median progression-free and overall survival were 5.4 months (95% confidence interval [CI], 4.6-6.4 months) and 10.0 months (95% CI, 7.9-11.7 months). The strongest predictors for favorable outcome were patient age ≤73.0 years (P= 0.0083), preoperative Karnofsky Performance Status Scale score ≥80% (P= 0.0179), postoperative modified Rankin Scale score ≤1 (P < 0.0001), adjuvant treatment (P < 0.0001), and no treatment-associated morbidity (P= 0.0478). Increased EOR did not correlate with survival (P= 0.5046), but correlated significantly with treatment-associated morbidity (P= 0.0031). Clinical outcome for elderly patients with GBM remains limited. Nonetheless, the observed treatment-associated morbidity and treatment burden were moderate in the patients, and patient age and performance status remained the strongest predictors for survival. The risks and benefits of tumor resection in the age of biomarker-adjusted treatment concepts require further prospective evaluation.