MGMT Promoter Research Articles

PATH-30. CLINICAL OUTCOMES AND PREDICTIVE BIOMARKERS FOR IDH-WILDTYPE GLIOBLASTOMAS DEVELOPING HYPERMUTATION FOLLOWING TEMOZOLOMIDE TREATMENT

Abstract Current standard of care for IDH-wildtype glioblastoma (GBM) includes maximal safe resection, adjuvant radiation, and chemotherapy with the alkylating agent temozolomide. A subset of gliomas treated with temozolomide develop somatic hypermutation with a predominance of C>T transitions due to the alkylation effects on DNA. However, the frequency of occurrence, clinical ramifications, and predictive biomarkers for developing temozolomide-induced hypermutation (TMZ-HM) in GBM are unknown. Here we performed comprehensive histopathologic, genomic, and epigenomic evaluation of paired initial and recurrent GBM from 106 patients. Seven patients (7%) developed hypermutation at time of first recurrence, while an additional five patients (5%) developed hypermutation at a subsequent recurrence. Patients who developed TMZ-HM had a significantly longer interval between initial surgery and first recurrence (27.8 vs. 9.9 months, p<0.001). In contrast to IDH-mutant gliomas where TMZ-HM is associated with poor prognosis, those patients with IDH-wildtype GBM who developed TMZ-HM had significantly longer overall survival from both initial surgery (67.9 vs. 20.3 months, p<0.001) and from time of recurrence after development of hypermutation (30.9 vs. 9.5 months, p=0.001). There was no difference in oncogenic alteration frequency in initial GBM that subsequently developed TMZ-HM. However, 4 specific CpG sites out of 12 total interrogated sites in the promoter region of MGMT (a DNA repair enzyme) and 5 specific CpG sites in the promoter region of KCNQ1DN (a negative regulator of c-Myc) were significantly more hypermethylated in those GBM that developed TMZ-HM. We then generated a weighted risk score across these CpG sites that can be used to prospectively identify GBM likely to develop TMZ-HM associated with favorable survival. In summary, patients with GBM that develop TMZ-HM follow a more favorable clinical course, and specific MGMT and KCNQ1DN promoter hypermethylation patterns could serve as a biomarker to identify these patients who may potentially benefit from extended alkylating chemotherapy treatment.

Loss of O6-methylguanine DNA methyltransferase (MGMT) in macrophages alters responses to TLR3 stimulation and enhances DNA double-strand breaks and mitophagy

Loss of O6-methylguanine DNA methyltransferase (MGMT) in macrophages alters responses to TLR3 stimulation and enhances DNA double-strand breaks and mitophagy

DDDR-45. INVESTIGATING TEMOZOLOMIDE RESISTANCE IN GLIOBLASTOMA USING A CLINICALLY RELEVANT DOSING REGIMEN

Abstract The standard of care of management for glioblastoma, the most common primary malignant brain tumor in adults, involves maximal safe surgical resection followed by adjuvant chemoradiotherapy and six cycles of adjuvant temozolomide (TMZ). Approximately half of all treated patients develop chemoresistance to TMZ. The evolution of chemoresistance to temozolomide in vitro has historically involved continuous exposure to drug, as opposed to clinical dosing schedules, which involve five days of treatment followed by 23 days of recovery. Thus, in this study, we examined the emergence of chemoresistance to TMZ in vitro, using a clinical dosing regimen. Temozolomide dose response to RN1, an MGMT promoter unmethylated, IDH-wildtype, patient-derived glioblastoma cell line, was determined using cell titer glo. Cells were treated with TMZ for five days, followed by 23 days of recovery, in cycles. In each subsequent cycle, the dose of TMZ used was adjusted to previous cycle’s IC50, the concentration at which 50% of cell growth is inhibited. This protocol was repeated over three rounds. Cells treated with TMZ, as compared to the DMSO-treated control population, gradually acquired chemoresistance with a continuous increase in IC50. Our protocol therefore highlights how a clinically relevant dosing regimen may help capture the trajectory by which chemoresistance emerges, also allowing for the exploration of the molecular mechanisms underlying this phenomenon.

QLTI-04. UPDATE ON HIGH-GRADE GLIOMA PATIENTS TREATED WITH TTFIELDS FROM NANFANG HOSPITAL IN CHINA

Abstract OBJECTIVE Tumour-treating fields (TTFields) have changed the first-line clinical practice of glioblastoma worldwide due to their promising therapeutic efficacy. The aim of this study was to investigate the clinical efficacy of TTFields therapy for HGG in Nanfang Hospital, China. In 2023 ASNO we reported PFS.Now we reporte update about OS from our single center study. METHODS From January 2019 to December 2022, a total of 25 patients with newly diagnosed HGG (ndHGG) treated with TTFields were retrospectively included in our study. Among these patients, 9 patients received concurrent radiochemotherapy in combination with TTFields and 16 patients received non-concurrent chemoradiotherapy in combination with TTFields. The primary endpoint of the study was mPFS and mOS (Kaplan-Meier method used to estimate PFS and OS survival curves). Secondary endpoint was the influences about KPS score in PFS and OS. RESULTS The 25 ndHGG patients treated with TTFields included nine males and sixteen females with a mean age of 47.1 years (12-68). Gross total resection (GTR) was performed in eighteen patients. Twenty-one patients were IDH wild type, eleven patients showed methylation of the MGMT promoter. Followed up until January 2024, the median PFS was 13.3 months [95% CI: 11.33-15.2] with TTFields combined and 4.0 months (95% CI, 3.8-4.4) without TTFields treatment in EF-14.Median OS was 26.53 months [95% CI:19.47-33.57] with TTFields and 16.0 months (95% CI, 3.8-4.4) control in EF-14. In the KPS stratification, OS was 27.5 months (95% CI: 22.95-32.1) vs 4.3 months (95% CI: 0-11.2), p=0.0001. The OS of patients with concurrent chemoradiotherapy combined with TTFields vs. without concurrent chemoradiotherapy combined with TTFields was 26.5 months (95% CI: 24.33-28.7) vs 21.2 (95% CI: 3.1-39.3) months, p=0.59. CONCLUSIONS TTFields therapy is an effective treatment for HGG. In this study the addition of TTFields resulted in a statistically significant improvement in PFS and OS.

PATH-26. MIDLINE INVOLVEMENT IS ASSOCIATED WITH ABERRANT RB1 SIGNALING IN PATIENTS WITH GRADE 4 IDH-MUTANT ASTROCYTOMA

Abstract BACKGROUND The prognostic factors impacting the survival of grade 4 IDH-mutant astrocytoma treated with standard radiation/temozolomide are not well-described. METHODS A retrospective cohort was generated of all patients diagnosed at Mayo Clinic with grade 4 IDH-mutant astrocytoma (2021 WHO Classification) on initial diagnosis between 2002-2023, and who received standard radiation/temozolomide. The impact of patient, tumor and molecular variables on overall survival (OS) and progression-free survival (PFS) was evaluated using survival analyses and Cox regression models. RESULTS Fifty-eight patients were identified. The median age was 36 years, 64% were male and 93% were white. The median follow up was 3.3 years. The median OS and PFS were 6.9 years and 2.4 years, respectively. CDKN2A/B homozygous deletion significantly reduced both OS (2.5 years vs NR, HR=3.9, p=0.0168) and PFS (1.4 vs 4.5 years, HR=4.2, p=0.0005). Midline involvement (brainstem, basal ganglia, thalamus, cerebellum or corpus callosum) also significantly reduced both OS (2.4 vs 12.8 years, HR=7.0, p=0.0014) and PFS (1.4 vs 4.5 years, HR=4.8, p=0.0002). MGMT promoter hypermethylation showed a trend toward significance for PFS (p=0.082) but did not impact OS. Age, sex, tumor size, ATRX immunohistochemistry and tumor-treating field therapy did not impact survival outcomes. Multivariable analyses revealed that PFS remained significantly impacted by both CDKN2A/B homozygous deletion (HR=3.5, p=0.0051) and midline involvement (HR=3.1, p=0.0125). A significant association between CDKN2A/B homozygous deletion and midline involvement was unexpectedly observed (53% if midline, 24% if non-midline; χ2=4.3, p=0.037). Exploratory analyses revealed that 15/15 (100%) of patients with midline involvement demonstrated aberration in RB1 signaling (CDKN2A/B homozygous deletion, n=8; CDKN2A/B hemizygous deletion or loss of heterozygosity, n=6; CDK4 amplification, n=1). CONCLUSION CDKN2A/B homozygous deletion and midline involvement independently impact PFS in patients with grade 4 IDH-mutant astrocytoma treated with standard radiation/temozolomide. Furthermore, midline involvement may be associated with aberrant RB1 signaling.

CTNI-49. PRECISION MEDICINE CLINICAL TRIAL FOR ADULT PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract Salvage therapies for recurrent glioblastoma (rGBM) have limited efficacy, with median overall survival of 9 months (OS-9) and 6-month progression-free survival (PFS-6) of 10-25%. Given GBM’s molecular heterogeneity, targeting a single molecular abnormality in isolation has consistently failed as a strategy, and precision combination approaches are needed. An initial 15-patient cohort evaluated the feasibility and safety of treating patients with rGBM with an individualized treatment regimen; we added a second 15-patient expansion cohort to improve the power of preliminary efficacy assessment. Patients underwent clinically indicated surgery with genomic profiling using the UCSF500 targeted DNA sequencing panel. Each personalized treatment regimen combined up to 4 FDA-approved drugs, including one cytotoxic agent, as determined by consensus discussion at an individualized molecular tumor board for each patient. Bevacizumab was not utilized in these combinations. The primary objective of the combined 30-patient cohort was efficacy of individualized treatment regimens by OS-9; secondary objectives included safety and additional efficacy measures including PFS-6. Median age was 53 years (range 32-71). Of 30 patients, 18 were male, 23 were enrolled at first recurrence, 29 had IDH-wildtype glioblastoma, 1 had IDH-mutant astrocytoma, and 10 had MGMT promoter methylation. A total of 12 FDA-approved drugs were used in 18 combinations; the most common regimen prescribed was lomustine, afatinib, and abemaciclib (7; 23%,); second-most common was temozolomide, olaparib, and afatinib (4; 13%). OS-9 of the combined cohort was 70% (95% CI 0.55 – 0.89) and PFS-6 was 27% (95% CI 0.15 – 0.48), with median OS of 11.6 months (95% CI 9.7 – 16.7) and median PFS of 3.7 months (95% CI 2.0 – 5.5).While overall efficacy was modest, implementation of individualized treatment regimens in a timely fashion was safe and feasible for patients with surgically resectable rGBM. Analysis is ongoing to assess whether specific genomic profiles or treatment regimens were particularly efficacious.

To Use or Not to Use: Temozolomide in Elderly Patients with IDH Wild-type MGMT Promoter Unmethylated Glioblastoma Treated with Radiotherapy

To Use or Not to Use: Temozolomide in Elderly Patients with IDH Wild-type MGMT Promoter Unmethylated Glioblastoma Treated with Radiotherapy

CTNI-44. NCT03643549 PHASE IB/II TRIAL: EFFICACY, SAFETY, AND BIOLOGICAL MECHANISMS OF OBJECTIVE RESPONSES IN RECURRENT GBM PATIENTS WITH UNMETHYLATED MGMT PROMOTER TREATED WITH SEQUENTIAL BORTEZOMIB AND TEMOZOLOMIDE

Abstract BACKGROUND Glioblastoma (GBM) is amongst the deadliest malignancies in adults, but especially for patients with unmethylated MGMT promoter (uMGMT) who gain limited benefit from the standard treatment. We previously demonstrated that proteosome inhibitor bortezomib (BTZ), inhibited NFkB activation,depleted MGMT protein and sensitized uMGMT GBM cells to Temozolomide (TMZ). Thus, a phase I/II trial testing sequential combination BTZ+TMZ was launched to investigate safety and clinical benefit. METHODS Recurrent GBM patients with uMGMT promoter, progressing ≥12 weeks after radiotherapy, KPS≥70 and radiologically measurable lesions were enrolled. The trial was powered for n=63 patients compared with n=102 historical controls. Patients received BTZ 1.3mg/m² IV on days 1, 4, and 7 of each 4-week cycle, starting on day 3 with oral 200mg/m² TMZ for 5 days/week. Whole exome sequencing (WES) of tumor DNA was conducted to identify genetic changes and LC-MS/MS used to asses proteomic changes in plasma collected during treatment. RESULTS As of January 2024, 54 patients (median 55y (25-70); 38 males, 16 females) were treated. The median KPS 90 (range 70-100) and NANO score was 1 (range 0-7). QoL was preserved, with mild /moderate adverse events. Adjusted analyses showed overall survival (OS) of 16.2 months compared to 8.4 months for uMGMT control patients, HR0.48, 95%CI[1.057-2.74],P=0.028. Objective radiological responses stable disease or better were observed in 22% (12/54) patients. Survival from recruitment was 10.5 months for responders vs. 4.8 months for rest of cohort, P=0.054 HR2.55, 95%CI[0.984-5.94]. Preliminary data indicate 78% (7/9) of responders harboured amplified EGFR vs. 38% in rest-of-the patients. The responders differentially expressed proteins critical for cellular processes, including ADAMTSL4, NCAM1, AZGP1, MMP2, CD163, and IL6ST. CONCLUSION Sequential BTZ+TMZ therapy is safe, effective and showed clinical benefit. EGFR amplification may be a predictive biomarker for response through NFκB activation, that is targeted by BTZ thereby depleting MGMT protein and enhancing treatment efficacy. Sequential BTZ+TMZ treamtment may represent additional treatment option at recurrence.

EPCO-24. WHAT SCRNA SEQUENCING TAUGHT US ABOUT MGMT EXPRESSION IN GLIOBLASTOMA

Abstract INTRODUCTION The promoter methylation status of O-6-methylguanine-DNA methyltransferase (MGMTp) is an established predictive and prognostic marker in GBM. Previous studies showed that the expression of MGMT based on immunohistochemistry was variable and lacked association with survival. This in part is because non-tumor cells including endothelial cells and macrophages express MGMT. Advanced technologies such as single-cell RNA (scRNA) sequencing have helped to elucidate the cellular composition of cancer and its microenvironment. scRNA sequencing allows to assess gene expression level in tumor cells specifically. METHODS We used publicly available data from two recent IDHwt GBM scRNA studies that included MGMTp methylation status data to explore and uncover details about MGMT expression at the single-cell level: CPTAC (13 primary samples) and Neftel (20 primary samples). RESULTS In the CPTAC study, MGMT gene expression ranged from 0.19%-1.43% in the MGMTp methylated group (median 0.82%), and from 2.17%-28.36% in the MGMTp unmethylated group (median 5.7%). It therefore appears that 2% is a reasonable expression cutoff to predict the MGMTp methylation status based on scRNA data. In the Neftel study, MGMT expression ranged from 0-1.26% in the MGMTp methylated group (median 0.59%), and from 0.3-27.67% in the MGMTp unmethylated group (median 12.44%). Three unmethylated samples (out of 16) did not follow the 2% rule. It is unclear if this is due to simply inaccurate annotation of these samples. Moreover, the Neftel paper did not specify the method used to detect MGMTp methylation. Alternatively, could it be that truly MGMTp unmethylated samples can have low MGMT expression? Could this explain why some unmethylated MGMTp GBM patients surpass the expected survival? Interestingly, gene set enrichment analysis shows that MGMT expressing cells are enriched with mesenchymal genes, whereas MGMT negative cells are enriched with proneural genes. CONCLUSION Fewer than 2% of GBM cells express MGMT if MGMTp is methylated.

PATH-31. COMPLETE TUMOR DISAPPEARANCE ON BRAIN MRI AFTER STANDARD CHEMORADIATION THERAPY FOR A MOLECULAR GLIOBLASTOMA

Abstract INTRODUCTION Glioblastoma (GBM) is the most aggressive brain tumor. The WHO CNS5 classification has newly incorporated three molecular criteria in diagnosing molecular GBM, including a concurrent gain of chromosome 7 and loss of chromosome 10 (+7/-10), TERT promoter mutation, or EGFR amplification. Despite new classification, the Stupp protocol remains the standard of care for all GBMs. However, it is unclear if the treatment response of the molecular GBM with low grade features is the same as the limited response of the traditional histopathological GBM. CASE REPORT A 74-year-old male presented in August of 2023 with new onset left-sided facial numbness. The numbness resolved spontaneously that day. Brain MRI was notable for a diffuse left frontal T2/Flair hyperintense lesion extending across the corpus callosum into the right frontal lobe without definite enhancement. Brain biopsy from 8 sites of the tumor demonstrated a subset of areas with mild hyper-cellularity, suggesting a low-density infiltrating glioma. However, TERT promoter mutation (-124C>T), was detected along with wild-type IDH1, supporting molecular GBM. Studies also found unmethylated MGMT gene promotor. Brain MRIs after 3 and 6 months showed no tumor progression. The patient has remained asymptomatic apart from baseline mild forgetfulness. He was started on the 6-week standard concomitant temozolomide and radiation therapy. Follow-up brain MRI after the above treatment showed complete imaging resolution of the tumor. DISCUSSION It is very rare for complete imaging resolution of GBM on brain MRI after standard 6-week chemoradiation therapy. Our case suggests that molecular GBM with low-grade features on imagine and pathology might have a better response to the standard treatment than traditional histopathological GBM even though the molecular GBM patient has unfavorable prognostic factors such as unmethylated MGMT and older age (>70 years old). Our experience emphasizes the heterogenous response of molecular GBM to the current standard treatment.

Development and validation of a clinical risk model for postoperative outcome in newly diagnosed glioblastoma: a report of the RANO resect group.

Following surgery, patients with newly diagnosed glioblastoma frequently enter clinical trials. Nuanced risk assessment is warranted to reduce imbalances between study arms. Here, we aimed (I) to analyze the interactive effects of residual tumor with clinical and molecular factors on outcome and (II) to define a postoperative risk assessment tool. The RANO resect group retrospectively compiled an international, seven-center training cohort of patients with newly diagnosed glioblastoma. The combined associations of residual tumor with molecular or clinical factors and survival were analyzed, and recursive partitioning analysis was performed for risk modeling. The resulting model was prognostically verified in a separate external validation cohort. Our training cohort compromised 1003 patients with newly diagnosed isocitrate dehydrogenase-wildtype glioblastoma. Residual tumor, O6-methylguanine DNA methyltransferase (MGMT) promotor methylation status, age, and postoperative KPS were prognostic for survival and incorporated into regression tree analysis. By individually weighting the prognostic factors, an additive score (range, 0-9 points) integrating these four variables distinguished patients with low (0-2 points), intermediate (3-5 points), and high risk (6-9 points) for inferior survival. The prognostic value of our risk model was retained in treatment-based subgroups and confirmed in an external validation cohort of 258 patients with glioblastoma. Compared to previously postulated models, goodness-of-fit measurements were superior for our model. The novel RANO risk model serves as an easy-to-use, yet highly prognostic tool for postoperative patient stratification prior to further therapy. The model may serve to guide patient management and reduce imbalances between study arms in prospective trials.

Marine-Derived Therapeutics for the Management of Glioblastoma: A Case Series and Comprehensive Review of the Literature

Introduction: Glioblastoma is a fatal intracranial neoplasm that is refractory to treatment, with inevitable disease recurrence and progression to death. Marine-derived compounds, including those found in nutraceutical products, may provide therapeutic benefit in the setting of glioblastoma. We present two patient cases whose courses demonstrate a compelling role for marine-derived products in the management of glioblastoma. Cases: Case 1 describes a patient with MGMT promoter unmethylated glioblastoma who went on to complete standard of care chemoradiation along with concurrent use of a majority sea cucumber (MSC) blend known as SeaCare® (SeaCare, Torrington, CT, USA). Her survival of over 2 years significantly exceeds the recognized median survival time of glioblastoma. Case 2 describes a patient with a complicated course who experienced dramatic improvement after the initiation of the MSC blend, with an exceptional survival time of over 4 years post-diagnosis. Discussion: The mechanisms of marine-derived products that underlie these dramatic clinical effects are likely multifaceted but may hinge on the modification of the tumor immune microenvironment and suppression of tumorigenic effects. Specifically, the change in tumor-associated macrophages (TAMs) within the tumor microenvironment is central to this complex interplay. Conclusions: Ultimately, the use of marine products in the treatment of glioblastoma may present a novel and promising therapeutic strategy that warrants further investigation.

Efficacy of Adding Veliparib to Temozolomide for Patients With MGMT-Methylated Glioblastoma

The prognosis for patients with glioblastoma is poor following standard therapy with surgical resection, radiation, temozolomide, and tumor-treating fields. To evaluate the combination of veliparib and temozolomide in glioblastoma based on preclinical data demonstrating significant chemosensitizing effects of the polyadenosine diphosphate-ribose polymerase 1/2 inhibitor veliparib when combined with temozolomide. Patients with newly diagnosed glioblastoma with MGMT promoter hypermethylation who had completed concomitant radiation and temozolomide were enrolled between December 15, 2014, and December 15, 2018, in this Alliance for Clinical Trials in Oncology trial. The data for this analysis were locked on April 21, 2023. Patients were randomized and treated with standard adjuvant temozolomide (150-200 mg/m2 orally, days 1-5) combined with either placebo or veliparib (40 mg orally, twice daily, days 1-7) for 6 cycles. The primary end point for the phase 3 portion of the trial was overall survival (OS). There were 322 patients randomized during the phase 2 accrual period and an additional 125 patients randomized to complete the phase 3 accrual, for a total of 447 patients in the final phase 3 analysis. The median (range) age for patients was 60 (20-85) years and 190 patients (42.5%) were female. The median OS was 24.8 months (90% CI, 22.6-27.7) for the placebo arm and 28.1 months (90% CI, 24.3-33.3) for the veliparib arm (P = .17). The difference in survival did not meet the prespecified efficacy end point. However, there was a separation of the survival curves that favored the veliparib arm over 24 to 48 months of follow-up. The experimental combination was well tolerated with an acceptable elevation in grade 3 or 4 hematologic toxic effects. This trial found that adding veliparib to adjuvant temozolomide did not significantly extend OS in patients with newly diagnosed, MGMT-hypermethylated glioblastoma. ClinicalTrials.gov Identifier: NCT02152982.

Efficacy and Low Toxicity of Normo-Fractionated Re-Irradiation with Combined Chemotherapy for Recurrent Glioblastoma—An Analysis of Treatment Response and Failure

Background: Glioblastoma is the most common malignant brain tumor in adults. Even after maximal safe resection and adjuvant chemoradiotherapy, patients normally relapse after a few years or even months. Standard treatment for recurrent glioblastoma is not yet defined, with re-resection, re-irradiation, and systemic therapy playing key roles. Usually, re-irradiation is combined with concurrent chemotherapy, harnessing the radiosensitizing effects of alkylating agents. Methods: A retrospective analysis of 101 patients with recurrent glioblastoma treated with re-irradiation was conducted, evaluating the survival impact of concurrent chemotherapy regimens, as well as prior resection. Patients were subcategorized according to concurrent chemotherapy (temozolomide vs. CCNU vs. combination of both vs. none) and details are given regarding treatment toxicity and patterns of relapse after first- and second-line treatment. Results: Patients were treated with normo-fractionated re-irradiation (with prescription dose of ~40 Gy to the PTV), resulting in a moderate cumulative EQD2 (~100 Gy). The mean overall survival was 11.3 months (33.5 months from initial diagnosis) and mean progression free survival was 9.5 months. Prior resection resulted in increased survival (p < 0.001), especially when gross total resection was achieved. Patients who received concurrent chemotherapy had significantly longer survival vs. no chemotherapy (p < 0.01), with the combination of CCNU and TMZ achieving the best results. Overall survival was significantly better in patients who received the CCNU + TMZ combination at any time during treatment (first or second line) vs. monotherapy only. The treatment of larger volumes (mean PTV size = 112.7 cm3) was safe and did not result in worse prognosis or increased demand for corticosteroids. Overall, the incidence of high-grade toxicity or sequential radionecrosis (5%) was reasonably low and treatment was tolerated well. While second-line chemotherapy did not seem to influence patterns of relapse, patients who received TMZ + CCNU as first-line treatment had a tendency towards better local control with more out-field recurrence. Conclusions: Normo-fractionated re-irradiation appears to be safe and is accompanied by good survival outcomes, even when applied to larger treatment volumes. Patients amenable to undergo re-resection and achieving concurrent systemic therapy with alkylating agents had better OS, especially when gross total resection was possible. Based on existing data and experiences reflected in this analysis, we advocate for a multimodal approach to recurrent glioblastoma with maximal safe re-resection and adjuvant second chemoradiation. The combination of TMZ and CCNU for patients with methylated MGMT promoter yielded the best results in the primary and recurrent situation (together with re-RT). Normo-fractionated RT enables the use of more generous margins and is tolerated well.

Efficacy and safety of bevacizumab combined with temozolomide in the treatment of glioma a systematic review and meta-analysis of clinical trials.

Glioma is the most common malignant brain tumor in neurosurgery. Bevacizumab (BEV) is a monoclonal antibody that inhibits tumors by inhibiting vascular endothelial growth factor and reducing tumor angiogenesis. To evaluate the efficacy and safety of BEV combined with temozolomide (TMZ) in glioma, we performed a meta-analysis. PubMed, Embase, The Cochrane Library, and Web of Science databases were searched for randomized controlled trials comparing survival outcomes between TMZ combined with BEV and TMZ alone as well as cohort studies were included in our study. The primary outcome measures analyzed were overall survival (OS) and progression-free survival (PFS). A total of six randomized controlled trials and four cohort studies with a total of 2515 patients were included in our meta-analysis. The results of meta-analysis suggested that there were no significant improvements in overall survival, but the combination of TMZ and BEV prolonged progression-free survival, improved overall response rate (ORR), and increased the incidence of some adverse reactions, compared with TMZ alone. Subgroup analysis suggested sex, recursive partitioning analysis (RPA) grade, MGMT gene status and radiotherapy combination did not affect the improvement of OS with the combination of the two drugs, and RPA grade did not affect the improvement of PFS with the combination of the two drugs. The combination of TMZ and BEV can improve PFS as well as ORR in patients and has no benefit on OS. At the same time, the adverse reactions during the combination of the two drugs were acceptable.

Whole Genome Sequencing Analysis of Model Organisms Elucidates the Association Between Environmental Factors and Human Cancer Development

Determining a novel etiology and mechanism of human cancer requires extraction of characteristic mutational signatures derived from chemical substances. This study explored the mutational signatures of N-nitroso bile acid conjugates using Salmonella strains. Exposing S. typhimurium TA1535 to N-nitroso-glycine/taurine bile acid conjugates induced a predominance of C:G to T:A transitions. Two mutational signatures, B1 and B2, were extracted. Signature B1 is associated with N-nitroso-glycine bile acid conjugates, while Signature B2 is linked to N-nitroso-taurine bile acid conjugates. Signature B1 revealed a strong transcribed strand bias with GCC and GCT contexts, and the mutation pattern of N-nitroso-glycine bile acid conjugates in YG7108, which lacks O6-methylguanine DNA methyltransferases, matched that of the wild-type strain TA1535, suggesting that O6-methyl-deoxyguanosine contributes to mutations in the relevant regions. COSMIC database-based similarity analysis revealed that Signature B1 closely resembled SBS42, which is associated with occupational cholangiocarcinoma caused by overexposure to 1,2-dichlolopropane (1,2-DCP) and/or dichloromethane (DCM). Moreover, the inflammatory response pathway was induced by 1,2-DCP exposure in a human cholangiocyte cell line, and iNOS expression was positive in occupational cholangiocarcinomas. These results suggest that 1,2-DCP triggers an inflammatory response in biliary epithelial cells by upregulating iNOS and N-nitroso-glycine bile acid conjugate production, resulting in cholangiocarcinoma via DNA adduct formation.

PROLONGED SURVIVAL IN IDH-WILDTYPE GLIOBLASTOMA: CASE REPORTS, LITERATURE REVIEW AND CURRENT PERSPECTIVES OF MOLECULAR BEHAVIOR

Abstract AIMS Glioblastoma remains one of the most aggressive primary brain tumours, with a median survival of around 12 months despite advances in treatment. However, rare cases of long-term survival challenge this prognosis. The evaluation of age, tumour location, surgical approach and strategies, adjuvant therapy, and molecular behavior provides valuable prognostic and predictive information in patients with glioblastoma. METHOD We present a case report of two patients diagnosed with wild-type glioblastoma who have survived over 10 years post-primary surgery. A review of epidemiological data, preoperative and postoperative radiological reports, surgical approach, and histology reports were studied. Additionally, we review the current literature to explore current nuances in High-Grade Glioma Wild Type prognosis and potential future directions. Three major medical database engines, PubMed (Medline), Scopus (ELSEVIER), and Cochrane were used to conduct a thorough literature search. RESULTS Both patients underwent maximal safe resection followed by the Stupp Protocol, comprising adjuvant chemotherapy with temozolomide and radiotherapy. Our case report highlights two exceptional cases of prolonged survival in Glioblastoma patients, both under 51 years-old at the moment of diagnosis, early diagnosis with isolated lobar lesions, no compromise of deep white matter, and achieving maximal safe resection and functional independence. Molecular analysis revealed specific genetic in common, including IDH Wild Type, p53 mutation, retained ATRX expression, TERT mutation, and MGMT promoter methylation, consistent with a favourable prognosis. Moreover, patients without recurrence often exhibit distinct molecular profiles, such as MGMT promoter methylation, suggesting a potential subtype associated with prolonged survival. CONCLUSION Our case reports and literature review highlight the possibility of prolonged survival in Glioblastoma patients. The age, tumor location at the time of diagnosis, comprehensive treatment approaches, may contribute to improved outcomes. Molecular profiling, particularly assessing genetic mutations and MGMT promoter methylation, holds promise for identifying patients with a higher likelihood of prolonged survival.

MAPPING GLIOMAS: A RADIOGRAPHIC AND SPATIAL ANALYSIS ACCORDING TO THE 2021 WHO CLASSIfiCATION

Abstract AIMS The spatial positioning of gliomas within the brain significantly influences prognosis, potentially mirroring the genetic landscape of their precursor cells. Furthermore, the association between glioma subtypes and their spatial distribution underscores a complex interplay that may illuminate underlying pathogenetic mechanisms. This study explores the intricate relationship between the location of gliomas and their classification according to the 2021 WHO guidelines, aiming to unravel the spatial and genetic nuances that define glioma heterogeneity. METHOD In this study, preoperative anatomical MRI data from 242 glioma patients were meticulously analyzed to elucidate spatial distribution patterns in relation to tumor genetics. The imaging data underwent registration to the MNI-152 standard brain space, facilitating uniform analysis. Subsequent tumor segmentation and division of the brain into 84 distinct subregions allowed for a detailed examination of tumor locations. A statistical analysis was conducted to explore the stereospecific frequency of glioma occurrence across these subregions, correlating findings with tumor grade and pivotal genetic markers, including MGMT promoter methylation, IDH1 mutation, 1p/19q co-deletion, and CDKN2A/B homozygous deletion. RESULTS We developed 21 distinct tumor frequency atlases based on subtypes (Glioblastoma, Oligodendroglioma, Astrocytoma), biomarker status (IDH, 1p19q, MGMT, CDKN2A/B), and grade (2, 3, 4). Employing probability vectors for statistical analysis revealed a significant correlation among different subtypes, locations and overall survival. Furthermore, we used a Visualization tool to build a 3D heatmap for each tumor subtype, more intuitively illustrating spatial correlations. CONCLUSION Our study underscores the prognostic value of tumor location and its correlation with glioma subtypes and patient outcomes, suggesting a potential pathway to personalized treatments. Future efforts will focus on incorporating multi-omics data into spatial radiographic analyses.

MANAGEMENT OF THE OLDER PATIENT WITH GLIOBLASTOMA IN THE UK: AN INITIAL REPORT FROM THE HISTO-MOL GBM COLLABORATIVE

Abstract AIMS The management of older (>70 years old) patients with glioblastoma is challenging with significant variation in practice. Using the Histo-Mol GBM database we analysed the variation in practice across 11 UK centres. METHOD Biopsy confirmed glioblastoma patients diagnosed between 01/01-31/12/2021 were identified. Descriptive statistics were used to compare demographic, tumour and treatment characteristics, and the Kaplan-Meier method was used to analyse survival, assessed from surgery date. Differences in treatment between centres were assessed using one way ANOVA. RESULTS In 2021, 81/330 (24.5%) patients with glioblastoma were >70. Compared to younger patients, the older cohort had a greater proportion of males (79.0% vs 59.0%, p<0.001), a worse performance status (66.7% vs 79.5% ECOG PS 0-1, p<0.001), and more likely to have MGMT promoter methylation (30.9% vs 22.9%, p=0.027). Most patients received biopsy only (31/81, 38.3%), followed by subtotal resection (85-94% tumour resection) (26/81, 32.1%), whilst 8/81 (9.9%) underwent debulking, 8/81 near-total resection (95-99% tumour resection), and 8/81 gross total resection, with statistically significant variation in resection extent between centres (p=0.031). Adjuvant radiotherapy was used in 56/81 patients (69.1%) with no difference between centres (p=0.220). However, there was a statistically significant difference in radiotherapy regime between centres (p=0.041). 6/81 (7.4%) received conventional chemoradiotherapy, 28/81 (34.6%) hypofractionated chemoradiotherapy, 16/81 (19.8%) hypofractionated radiotherapy alone, 2/81 (2.5%) temozolomide alone both with MGMT promoter methylation, and 21/81 (25.9%) received no oncological treatment. Median progression free survival was 5.9 months and median overall survival (OS) was 7.1 months with no difference between centres (p=0.199 and p=0.083 respectively). Median OS was 8.4 months with conventional fractionation chemoradiotherapy, 11.2 months with hypofractionated chemoradiotherapy, 7.3 months with hypofractionated radiotherapy alone, 1.8 months with temozolomide alone, and 2.5 months with no oncological treatment. CONCLUSION We identify variations in the treatment of elderly glioblastoma patients across the UK, although these do not significantly impact survival.

GLIOBLASTOMA IN THE UK POST WHO CNS 5: INITIAL fiNDINGS FROM THE HISTO-MOL GBM COLLABORATIVE

Abstract AIMS The 2021 World Health Organisation Classification (WHO CNS5) incorporated molecular diagnostic features for glioblastoma for the first time. The Histo-Mol GBM collaborative is conducting a retrospective cohort study evaluating the outcomes of patients prospectively diagnosed with WHO CNS5 IDH wild type glioblastoma. METHOD Biopsy confirmed glioblastoma patients diagnosed between 01/01-31/12/2021 were identified. Demographic, tumour, treatment, and survival data were collected. Descriptive statistics and Kaplan-Meier method were used to describe the cohort and for survival analysis respectively, assessed from surgery date. RESULTS So far, 363 glioblastoma patients were included from 13 centres (range: 11-61 patients/centre). Median age was 63.0, 65.8% were male, 77.4% had an ECOG performance status of 0-1 at diagnosis, and 28/333 had a molecular glioblastoma (8.4%). Biopsy was performed in 106/363 patients (29.2%), and gross total resection in 50/363 (13.8%). Adjuvant radiotherapy was performed in 290/363 (79.9%), and 71/290 (24.5%) had an additional pre-radiotherapy MRI with rapid early progression identified in 30/71 patients (42.3%). 128/269 (47.6%) patients received 2nd line treatment; most commonly systemic therapy (91/128, 71.1%) followed by re-resection (27/128, 21.1%). Second line systemic therapy was primarily lomustine (48/81, 52.7%). Median progression free survival was 7.7 months and median overall survival (OS) was 11.6 months. Median OS was 16.9 months with conventional fractionation chemoradiotherapy (n=169/363, 46.6%), 10.4 months with hypofractionated chemoradiotherapy (n=64/363, 17.6%), and 2.3 months with no oncological treatment (n=57/363, 15.7%). On univariate analysis age, gender, performance status, multifocality, MGMT promoter methylation, surgery extent, radiotherapy type (none, palliative, hypofractionated, conventional fractionation), larger planning target volume (PTV), receiving concurrent temozolomide, and receiving adjuvant temozolomide were statistically significant. On multivariate analysis age, and receiving concurrent temozolomide remained significant. CONCLUSION We describe the initial findings from a large real-world cohort of glioblastoma patients prospectively diagnosed according to WHO CNS5. Survival compares favourably with the practice changing phase 3 clinical trial outcomes.