Unmethylated MGMT Promoter Research Articles

Macrophage polarization-related gene signature for risk stratification and prognosis of survival in gliomas.

Macrophage polarization plays an essential role in tumour immune cell infiltration and tumour growth. In this study, we selected a series of genes distinguishing between M1 and M2 macrophages and explored their prognostic value in gliomas. A total of 170 genes were included in our study. The CGGA database was used as the training cohort and the TCGA database as the validation cohort. The biological processes and functions were identified by GO and KEGG analysis. Kaplan-Meier analysis was used to compare survival differences between groups. Importantly, we built a risk score model using Cox regression analysis based on the CGGA and verified it in the TCGA database and our sequencing data. Patients with gliomas in the high-risk group were associated with high pathologic grade, IDH WT status, MGMT promoter unmethylation, 1p19q non-codeletion and prone to have a poor outcome. GEPIA results revealed that CD300C, CNRIP1 and MYO1F are the most related genes of immune infiltrations. The differential expression of these genes between low-grade gliomas and glioblastomas was confirmed by q-RT-PCR. Macrophage polarization-related gene signatures can predict the malignancy and outcome of patients with gliomas and might act as a promising target for glioma immunotherapy in the future.

MGMT protein expression is a reliable predictive biomarker for temozolomide-containing chemotherapy in osteosarcoma.

The prognosis of patients with osteosarcoma who experience recurrence or progression (R/P) is extremely poor, and more effective and less toxic therapies are needed. In the current study, the clinical data of osteosarcoma patients who experienced R/P were retrospectively analyzed to verify the reliability of O-6-methylguanine-DNA methyltransferase (MGMT) protein expression or MGMT promoter methylation for predicting the response to off-label temozolomide (TMZ)-containing chemotherapy. Of the 30 evaluable patients, 9 (30%) showed no/low MGMT protein expression, whereas all 16 evaluable patients had unmethylated MGMT promoter irrespective of MGMT protein expression levels. Twenty-three patients received TMZ-containing chemotherapy for measurable lesions (n = 14) or as adjuvant therapy following resection of recurrent lesions (n = 9). Among 14 patients with radiologically measurable lesions, the objective response rate was higher in the MGMT no/low-expression group (50.0%) than in the MGMT intermediate/high-expression group with borderline significance (0%, p = 0.066). The 6-month progression-free survival (PFS) rate in patients with radiologically measurable lesions was significantly higher in the MGMT no/low-expression group (50.0%) than in the MGMT intermediate/high-expression group (0%, p = 0.036). In the multivariate analysis of the 23 patients receiving TMZ-containing chemotherapy, MGMT expression and disease status before TMZ-containing chemotherapy were significantly associated with PFS. No severe adverse effects were observed during TMZ-containing chemotherapy. MGMT protein expression, but not MGMT promoter methylation, could predict a favorable outcome in patients receiving TMZ-containing chemotherapy.

No benefit from TMZ treatment in glioblastoma with truly unmethylated MGMT promoter: Reanalysis of the CE.6 and the pooled Nordic/NOA-08 trials in elderly glioblastoma patients.

The treatment of elderly/ frail patients with glioblastoma is a balance between avoiding undue toxicity, while not withholding effective treatment. It remains debated, whether these patients should receive combined chemo-radiotherapy with temozolomide (RT/TMZ→TMZ) regardless of the O6-methylguanine DNA methyltransferase gene promoter (MGMTp) methylation status. MGMT is a well-known resistance factor blunting the treatment effect of TMZ, by repairing the most genotoxic lesion. Epigenetic silencing of the MGMTp sensitizes glioblastoma to TMZ. For risk-adapted treatment, it is of utmost importance to accurately identify patients, who will not benefit from TMZ treatment. Here, we present a reanalysis of the clinical trials CE.6 and the pooled NOA-08 and Nordic trials in elderly glioblastoma patients that compared RT to RT/TMZ→TMZ, or RT to TMZ, respectively. For 687 patients with available MGMTp methylation data, we applied a cutoff discerning truly unmethylated glioblastoma, established in a pooled analysis of 4 clinical trials for glioblastoma, with RT/TMZ→TMZ treatment, using the same quantitative methylation-specific MGMTp PCR assay. When applying this restricted cutoff to the elderly patient population, we confirmed that glioblastoma with truly unmethylated MGMTp derived no benefit from TMZ treatment. In the Nordic/NOA-08 trials, RT was better than TMZ, suggesting little or no benefit from TMZ. For evidence-based treatment of glioblastoma patients validated MGMTp methylation assays should be used that accurately identify truly unmethylated patients. Respective stratified management of patients will reduce toxicity without compromising outcomes and allow testing of more promising treatment options.

Supramaximal resection: retrospective study on IDH-wildtype Glioblastomas based on the new RANO-Resect classification.

The prognostic value of the extent of resection in the management of Glioblastoma is a long-debated topic, recently widened by the 2022 RANO-Resect Classification, which advocates for the resection of the non-enhancing disease surrounding the main core of tumors (supramaximal resection, SUPR) to achieve additional survival benefits. We conducted a retrospective analysis to corroborate the role of SUPR by the RANO-Resect Classification in a single center, homogenous cohort of patients. Records of patients operated for WHO-2021 Glioblastomas at our institution between 2007 and 2018 were retrospectively reviewed; volumetric data of resected lesions were computed and classified by RANO-Resect criteria. Survival and correlation analyses were conducted excluding patients below near-total resection. 117 patients met the inclusion criteria, encompassing 45 near-total resections (NTR), 31 complete resections (CR), and 41 SUPR. Median progression-free and overall survival were 11 and 15months for NTR, 13 and 17months or CR, 20 and 24months for SUPR, respectively (p < 0.001), with inverse correlation observed between survival and FLAIR residual volume (r -0.28). SUPR was not significantly associated with larger preoperative volumes or higher rates of postoperative deficits, although it was less associated with preoperative neurological deficits (OR 3.37, p = 0.003). The impact of SUPR on OS varied between MGMT unmethylated (HR 0.606, p = 0.044) and methylated (HR 0.273, p = 0.002) patient groups. Results of the present study support the validity of supramaximal resection by the new RANO-Resect classification, also highlighting a possible surgical difference between tumors with methylated and unmethylated MGMT promoter.

Abstract CT044: A phase 0/1b study of AZD1390 plus radiotherapy in newly-diagnosed, MGMT-unmethylated glioblastoma patients

Abstract Background: ATM inhibition has been hypothesized to potentiate the effects of radiation by preventing acute phase DNA damage repair, and a Phase 1 trial of this combination in patients with GBM is ongoing (NCT03423628). To test this hypothesis, this Phase 0/1b study evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) of AZD1390, a first-in-class ATM inhibitor, in combination with radiation in newly-diagnosed GBM patients (NCT05182905). Methods: Presumed newly-diagnosed GBM patients received 3 days of AZD1390 prior to planned resection at 4-6 or 23-25 hours following the final dose. Tumor tissue, cerebrospinal fluid (CSF), and plasma were collected. Total and unbound drug concentrations were measured using validated LC-MS/MS methods. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase. ATM inhibition was assessed via ex vivo tissue radiation, quantifying pRAD50 levels compared to non-radiated control. Patients exceeding the PK threshold (2 nM unbound drug levels in Gd-non-enhancing tumor region) with unmethylated MGMT promoter were eligible for the expansion phase of study drug, combining AZD1390 with 6 weeks of radiotherapy. Results: Seventeen patients were enrolled into the study. All tested patients (n=14) exceeded the PK threshold and qualified for the expansion phase. Three patients were excluded from the PK analysis due to dosing deviation (n=1) and non-GBM diagnosis (n=2). The mean unbound concentration of AZD1390 in Gd-nonenhancing tumor was 12.4 and 4.4 pmol/g, respectively, for the 4-6 and 23-25-hours cohort. Following 5Gy ex vivo radiation of surgical specimen, pRAD50 expression was significantly suppressed in AZD1390 treated patients compared to untreated controls (median 0.2% for 4-6-hours cohorts and 1.9% for 23-25-hours cohort vs 32.3% for control cohort, average 99% and 95% reduction, respectively, p&amp;lt;0.01 for both cohorts vs control). As of 11/30/2023, 3 patients with unmethylated MGMT promoter are undergoing therapeutic dosing of AZD1390 plus radiotherapy, with median clinical follow-up of 2.3 months. Conclusion: AZD1390 is well-tolerated in newly-diagnosed GBM patients, achieving pharmacologically relevant concentrations in Gd-nonenhancing tumor tissue, and substantially suppressing radiation-induced increases in pRAD50 levels. These data are the first in GBM patients demonstrating AZD1390-mediated pharmacodynamic and pharmacokinetic response. Citation Format: Nader Sanai, Siddhi Desai, Tigran Margaryan, Jennifer Molloy, Costanza LoCascio, Mackenna Elliott, Jocelyn Harmon, Amy Hong, Ernesto Luna Melendez, John Wanebo, Kelly Braun, William Kennedy, Michael Garcia, Wonsuk Yoo, Artak Tovmasyan, An-Chi Tien, Shwetal Mehta. A phase 0/1b study of AZD1390 plus radiotherapy in newly-diagnosed, MGMT-unmethylated glioblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT044.

Abstract CT127: A macrophages-based immunotherapy of solid tumors microenvironment: Preliminary results of the TEM-GBM_01 study

Abstract Glioblastoma multiforme (GBM) is an incurable tumor affecting the central nervous system. The reported median survival in the unfavorable patients′ subgroup with unmethylated MGMT promoter is 12.7 months with less than the 15% of patient surviving up to 2–years. Despite immunotherapies being able to slow or eradicate numerous tumors, none so far have extended survival in GBM. Using genetically modified autologous CD34+ HSPCs, we developed an advance medicinal product, (Temferon) designed to deliver interferon–α2 within the TME by Tie–2 expressing macrophages (TEMs). Temferon is currently in the clinic in a Phase 1/2a dose-escalation non-randomized open label study in newly diagnosed GBM with unmethylated MGMT. The study aims to evaluate the short– (up to 90 days) and long– (up to 2 years) term tolerability and safety of 5 escalating doses in up to 27 GBM patients. Following a sub–myeloablative conditioning regimen (Thiotepa + BCNU or Thiotepa + Busulfan or Busulfan alone), up to 3 million Temferon cells/kg are administered with a fixed dose of non–manipulated CD34+ supporter cells As of 27th July 2023, 21 GBM patients in 7 cohorts received incremental Temferon doses and 5 patients were still alive with a 17 months median OS and a 8.3 months median PFS (95% CI) post surgery. To date, no DLTs have been identified. In all patients, rapid engraftment and fast hematological recovery have been observed within 2 weeks from the transplantation. Grade 4 or 5 serious adverse events (n=7 patients), were mostly attributed to the conditioning chemotherapy, but steroid usage or disease progression were also listed. 1 SUSAR (persistent GGT elevation) occurred. The higher transduced cells proportion in the BM was observed 30 days after Temferon with a chimerism for the highest dose tested up to 40%, still detectable in the long–term. Very low IFNα concentrations were detected in the plasma, indicating a tight vector expression regulation. 7 patients underwent second surgery and genetically engineered cells were detected (in 85%) within the bulk tumor lesion (&amp;gt;3% in 3 patients). IFN–responsive genes (IGS) were up–regulated, suggesting a local IFNα release by TEMs. In 1 patient, a stable lesion, compared to a synchronous, progressing lesion, had a higher proportion of T cells &amp; TEMs, an increased IGS e and myeloid re–programming. TCR blood and tumor sample sequencing showed a post–treatment increase of peripherally expanded clones frequency in the tumor samples, as evidence of a crosstalk between peripheral and tumor T cell repertoires . These data corroborate the initial evidence on safety and tolerability of Temferon and suggest that Temferon has potential to counteract disease progression in patients affected by unmethylated MGMT GBM. Clinical Trial Registry (if applicable): NCT03866109 Citation Format: Francesca Farina, Bernhard Gentner, Gaetano Finocchiaro, Marica Eoli, Alessia Capotondo, Elena Anghileri, Matteo Barcella, Valentina Brambilla, Matteo Carrabba, Valeria Cuccarini, Quintino Giorgio D'alessandris, Francesco DiMeco, Valeria Ferla, Paolo Ferroli, Filippo Gagliardi, Federico Legnani, Stefania Mazzoleni, Alessandro Olivi, Roberto Pallini, Marco Saini, Luigi Naldini, Carlo Russo, Fabio Ciceri. A macrophages-based immunotherapy of solid tumors microenvironment: Preliminary results of the TEM-GBM_01 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT127.

Identification of TMZ resistance-associated histone post-translational modifications in glioblastoma using multi-omics data.

Glioblastoma multiforme (GBM) is among the most aggressive cancers, with current treatments limited in efficacy. A significant hurdle in the treatment of GBM is the resistance to the chemotherapeutic agent temozolomide (TMZ). The methylation status of the MGMT promoter has been implicated as a critical biomarker of response to TMZ. To explore the mechanisms underlying resistance, we developed two TMZ-resistant GBM cell lines through a gradual increase in TMZ exposure. Transcriptome sequencing of TMZ-resistant cell lines revealed that alterations in histone post-translational modifications might be instrumental in conferring TMZ resistance. Subsequently, multi-omics analysis suggests a strong association between histone H3 lysine 9 acetylation (H3K9ac) levels and TMZ resistance. We observed a significant correlation between the expression of H3K9ac and MGMT, particularly in the unmethylated MGMT promoter samples. More importantly, our findings suggest that H3K9ac may enhance MGMT transcription by facilitating the recruitment of the SP1 transcription factor to the MGMT transcription factor binding site. Additionally, by analyzing single-cell transcriptomics data from matched primary and recurrent GBM tumors treated with TMZ, we modeled the molecular shifts occurring upon tumor recurrence. We also noted a reduction in tumor stem cell characteristics, accompanied by an increase in H3K9ac, SP1, and MGMT levels, underscoring the potential role of H3K9ac in tumor relapse following TMZ therapy. The increase in H3K9ac appears to enhance the recruitment of the transcription factor SP1 to its binding sites within the MGMT locus, consequently upregulating MGMT expression and driving TMZ resistance in GBM.

Pyrosequencing Analysis of O-6-Methylguanine-DNA Methyltransferase Methylation at Different Cut-Offs of Positivity Associated with Treatment Response and Disease-Specific Survival in Isocitrate Dehydrogenase-Wildtype Grade 4 Glioblastoma.

The O-6-methylguanine-DNA methyltransferase (MGMT) gene is a critical guardian of genomic integrity. MGMT methylation in diffuse gliomas serves as an important determinant of patients' prognostic outcomes, more specifically in glioblastomas (GBMs). In GBMs, the absence of MGMT methylation, known as MGMT promoter unmethylation, often translates into a more challenging clinical scenario, tending to present resistance to chemotherapy and a worse prognosis. A pyrosequencing (PSQ) technique was used to analyze MGMT methylation status at different cut-offs (5%, 9%, and 11%) in a sample of 78 patients diagnosed with IDH-wildtype grade 4 GBM. A retrospective analysis was provided to collect clinicopathological and prognostic data. A statistical analysis was used to establish an association between methylation status and treatment response (TR) and disease-specific survival (DSS). The patients with methylated MGMT status experienced progressive disease rates of 84.6%, 80%, and 78.4% at the respective cut-offs of 5%, 9%, and 11%. The number was considerably higher when considering unmethylated patients, as all patients (100%), regardless of the cut-off, presented progressive disease. Regarding disease-specific survival (DSS), the Hazard Ratio (HR) was HR = 0.74 (0.45-1.24; p = 0.251); HR = 0.82 (0.51-1.33; p = 0.425); and HR = 0.79 (0.49-1.29; p = 0.350), respectively. Our study concludes that there is an association between MGMT unmethylation and worse TR and DSS. The 9% cut-off demonstrated a greater potential for patient survival as a function of time, which may shed light on the future need for standardization of MGMT methylation positivity parameters in PSQ.

Association of MGMT Promoter and Enhancer Methylation with Genetic Variants, Clinical Parameters, and Demographic Characteristics in Glioblastoma.

The response of glioblastoma (GBM) patients to the alkylating agent temozolomide (TMZ) vitally depends on the expression level of the repair protein O6-methylguanine-DNA methyltransferase (MGMT). Since MGMT is strongly regulated by promoter methylation, the methylation status of the MGMT promoter has emerged as a prognostic and predictive biomarker for GBM patients. By determining the methylation levels of the four enhancers located within or close to the MGMT gene, we recently found that enhancer methylation contributes to MGMT regulation. In this study, we investigated if methylation of the four enhancers is associated with SNP rs16906252, TERT promoter mutations C228T and C250T, TERT SNP rs2853669, proliferation index Ki-67, overall survival (OS), age, and sex of the patients. In general, associations with genetic variants, clinical parameters, and demographic characteristics were caused by a complex interplay of multiple CpGs in the MGMT promoter and of multiple CpGs in enhancer regions. The observed associations for intragenic enhancer 4, located in intron 2 of MGMT, differed from associations observed for the three intergenic enhancers. Some findings were restricted to subgroups of samples with either methylated or unmethylated MGMT promoters, underpinning the relevance of the MGMT promoter status in GBMs.

NIMG-69. LEPTOMENINGEAL METASTASES IN IDH-WILDTYPE GLIOBLASTOMAS REVISITED: COMPREHENSIVE ANALYSIS OF INCIDENCE, RISK FACTORS, AND PROGNOSIS BASED ON POSTCONTRAST FLAIR IMAGING

Abstract BACKGROUND To comprehensively investigate the incidence, risk factors, and prognosis of leptomeningeal metastases (LM) in isocitrate dehydrogenase (IDH)-wildtype glioblastoma patients. METHODS Total 913 IDH-wildtype glioblastoma patients with complete molecular information on IDH mutation and MGMT promoter methylation status were enrolled between 2004 and 2022. LM diagnosis was performed with MRI including postcontrast FLAIR and CSF cytology. Logistic regression analysis for LM development at initial diagnosis and recurrence was performed with clinical, surgical, imaging, and molecular data. The overall survival (OS) was compared between patients with and without LM. RESULTS The incidence of LM was 21.8% (199 patients) among patients with IDH-wildtype glioblastoma, with 11.5% (105 patients) at initial diagnosis, and 10.3% (94 patients) at recurrence. Male sex (odds ratio [OR]: 1.74, P = 0.017), MGMT promoter unmethylation (OR: 1.48, P = 0.048), nonlobar location (OR: 2.27, P &amp;lt; 0.001), and presence of necrosis (OR: 3.64, P &amp;lt; 0.001) were independent predictors of LM at initial diagnosis, whereas ventricular opening during surgery (OR: 2.96, P &amp;lt; 0.001) was the only independent predictor of LM at recurrence. The median OS was 16.2 months (interquartile range [IQR]: 9.6-30.4) in patients with LM and 19.3 months (IQR: 12.1-38.5) in patients without LM (log-rank test; P = 0.001). CONCLUSION The incidence of LM is high in patients with IDH-wildtype glioblastoma. Aggressive clinical, imaging, and molecular factors are correlated with LM at initial diagnosis, whereas ventricular entry warrant imaging surveillance for LM at recurrence. The prognosis of LM is not discouraging as expected, and promote reconsideration of focused clinical trials.

CTNI-31. TREATMENT BENEFIT IN PATIENTS AGED 80 YEARS OR OLDER WITH BIOPSY-PROVEN AND NON-RESECTED GLIOBLASTOMA IS DEPENDENT ON MGMT PROMOTER METHYLATION STATUS

Abstract PURPOSE Glioblastoma is associated with especially poor outcome in the elderly. It is unclear if patients aged ≥ 80 years benefit from tumor-specific therapy as opposed to receiving best supportive care (BSC) only. METHODS Patients with IDH-wildtype glioblastoma (WHO 2021), aged ≥ 80 years, and diagnosed by biopsy between 2010 and 2022 were included. Patient characteristics and clinical parameters were assessed. Uni- and multivariate analyses were performed. RESULTS 76 patients with a median age of 82 (range 80–89) and a median initial KPS of 80 (range 50–90) were included. Tumor-specific therapy was initiated in 52 patients (68%). 22 patients (29%) received temozolomide monotherapy, 23 patients (30%) were treated with radiotherapy (RT) alone and 7 patients (9%) received combination therapies. In 24 patients (32%), tumor-specific therapy was omitted in lieu of BSC. Overall survival (OS) was longer in patients receiving tumor-specific therapy (5.4 vs. 3.3 months, p&amp;lt;0.001). Molecular stratification showed that the survival benefit was owed to patients with MGMT promoter methylation (MGMTpos) who received tumor-specific therapy as opposed to BSC (6.2 vs. 2.6 months, p&amp;lt;0.001), especially to those with better clinical status and no initial polypharmacy. Patients with unmethylated MGMT promoter (MGMTneg) did not benefit from tumor-specific therapy (3.6 vs. 3.7 months, p=0.18). In multivariate analyses, better clinical status and MGMT promoter methylation were associated with prolonged survival (p&amp;lt;0.01 and p=0.01). CONCLUSION Benefit from tumor-specific treatment in patients with newly diagnosed glioblastoma aged ≥ 80 years might be restricted to MGMTpos patients, especially to those with good clinical status and no polypharmacy.

Transcriptomic Characterization of Copper-Binding Proteins for Predicting Prognosis in Glioma.

Copper and copper-binding proteins are key components of tumor progression as they play important roles in tumor invasion and migration, but their associations in gliomas remain unclear. Transcriptomic datasets of glioblastoma, low-grade glioma, and normal brain cortex were derived from the TCGA and GTEX databases. Differentially expressed genes (DEGs) of copper-binding proteins were screened and used to construct a prognostic model based on COX and LASSO regression, which was further validated by the CGGA datasets. The expressions of risk-model genes were selectively confirmed via anatomic feature-based expression analysis and immunohistochemistry. The risk score was stratified by age, gender, WHO grade, IDH1 mutation, MGMT promoter methylation, and 1p/19q codeletion status, and a nomogram was constructed and validated. A total of 21 DEGs of copper-binding proteins were identified and a six-gene risk-score model was constructed, consisting of ANG, F5, IL1A, LOXL1, LOXL2, and STEAP3, which accurately predicted 1-, 3-, and 5-year overall survival rates, with the AUC values of 0.87, 0.88, and 0.82, respectively. The high-risk group had a significantly shorter OS (p < 0.0001) and was associated with old age, wild-type IDH1, a high WHO grade, an unmethylated MGMT promoter, and 1p/19q non-codeletion and had higher levels of immune cell infiltration, cancer-immunity suppressor, and immune checkpoint gene expression as well as a higher TMB. The model based on the genes of copper-binding proteins could contribute to prognosis prediction and provide potential targets against gliomas.

Genome-wide DNA methylation analysis identifies potent CpG signature for temzolomide response in non-G-CIMP glioblastomas with unmethylated MGMT promoter: MGMT-dependent roles of GPR81.

To identify potent DNA methylation candidates that could predict response to temozolomide (TMZ) in glioblastomas (GBMs) that do not have glioma-CpGs island methylator phenotype (G-CIMP) but have an unmethylated promoter of O-6-methylguanine-DNA methyltransferase (unMGMT). The discovery-validation approach was planned incorporating a series of G-CIMP-/unMGMT GBM cohorts with DNA methylation microarray data and clinical information, to construct multi-CpG prediction models. Different bioinformatic and experimental analyses were performed for biological exploration. By analyzing discovery sets with radiotherapy (RT) plus TMZ versus RT alone, we identified a panel of 64 TMZ efficacy-related CpGs, from which a 10-CpG risk signature was further constructed. Both the 64-CpG panel and the 10-CpG risk signature were validated showing significant correlations with overall survival of G-CIMP-/unMGMT GBMs when treated with RT/TMZ, rather than RT alone. The 10-CpG risk signature was further observed for aiding TMZ choice by distinguishing differential outcomes to RT/TMZ versus RT within each risk subgroup. Functional studies on GPR81, the gene harboring one of the 10 CpGs, indicated its distinct impacts on TMZ resistance in GBM cells, which may be dependent on the status of MGMT expression. The 64 TMZ efficacy-related CpGs and in particular the 10-CpG risk signature may serve as promising predictive biomarker candidates for guiding optimal usage of TMZ in G-CIMP-/unMGMT GBMs.

P10.06.B APPLYING TUMOR TREATING FIELDS (TTFIELDS) FOR ENHANCEMENT OF TEMOZOLOMIDE AND LOMUSTINE EFFICACY IN GLIOBLASTOMA CELL LINES

Abstract BACKGROUND Tumor Treating Fields (TTFields) are electric fields that disrupt cellular processes critical for cancer cell viability and tumor progression, ultimately leading to cell death. TTFields therapy concurrent with maintenance temozolomide (TMZ) is approved for treatment of newly-diagnosed glioblastoma (GBM). Recently, benefit was demonstrated in patients with O6-methylguanine DNA methyltransferase (MGMT) promoter methylation for the combination of TMZ with lomustine (CCNU). The addition of adjuvant TTFields to this treatment regimen further improved patient outcomes, leading to a CE mark. The current study aimed to elucidate the mechanism underlying the benefit of this treatment protocol by utilizing GBM cell lines with different MGMT expression status. MATERIAL AND METHODS Human GBM cell lines with different MGMT promoter methylation status [LN-18 (unmethylated MGMT promoter), U-118 MG (partially methylated MGMT promoter), and U-87 MG and LN-229 (methylated MGMT promoter)] were examined for MGMT expression levels. Next, the cells were treated with TTFields (intensity of 0.83 V/cm RMS; frequency of 200 kHz) using the inovitro system. Cell count and colony formation were employed to detect the effectiveness of TTFields concomitant with TMZ and/or CCNU. Western blot allowed the detection of expression levels of DNA repair proteins in control versus TTFields-treated cells. RESULTS The cell lines displayed comparable responses to TTFields and CCNU, while they differed in sensitivity to TMZ according to MGMT expression status. TTFields concomitant with TMZ displayed an additive effect, irrespective of MGMT expression levels. The effect of concomitant TTFields with CCNU was additive in MGMT-expressing cell lines, whereas it trended toward synergy in MGMT-non-expressing cell lines. Expression of proteins from the Fanconi Anemia (FA)-BRCA pathway for DNA repair was downregulated following TTFields application. TTFields concurrent with both TMZ and CCNU provided higher efficacy relative to TMZ plus CCNU or TTFields apart, with additivity in MGMT-expressing cell lines and a tendency toward synergy in MGMT-non-expressing cell lines. CONCLUSION The results support the clinical benefit demonstrated for concomitant TTFields with TMZ plus CCNU, showing that the efficacy of TMZ and CCNU may be enhanced by TTFields, with synergism seen for the latter case in cells not expressing MGMT. The BRCAness state induced by TTFields rationalizes this, as in the absence of MGMT DNA damage induced by CCNU requires the FA-BRCA pathway for repair.

P06.08.A CLINICAL OUTCOME AND TRANSLATIONAL INSIGHTS FROM A PHASE I/II TRIAL WITH THE TUMOR-TARGETING ANTIBODY-CYTOKINE FUSION PROTEIN L19TNF FOR PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract BACKGROUND Treatment options for recurrent glioblastoma are limited and there is a need for novel effective therapies. Cytokine-based therapies are promising cancer immunotherapies that potentially can convert an immunologically “cold” tumor microenvironment into a “hot” one and may trigger potent antitumor immunity. However, the systemic administration of pro-inflammatory cytokines at therapeutically active doses is hampered by toxic side effects. L19TNF is a fully human antibody-cytokine fusion protein, comprising tumor necrosis factor (TNF) fused to the antibody L19 that binds a tumor-specific epitope of fibronectin. This allows targeted delivery of relevant doses of TNF to the tumor while sparing healthy organs. Here, we report the results of a clinical trial with systemically administered L19TNF as monotherapy for patients with recurrent glioblastoma. MATERIAL AND METHODS NCT03779230 was an open-label, non-randomized, multicenter phase I/II clinical trial to investigate the safety and preliminary efficacy of L19TNF monotherapy for patients with IDH-wildtype WHO grade 3/4 glioma at first relapse. L19TNF was administered intravenously in three-week cycles. Tumor responses were assessed by iRANO criteria. Accompanying translational research comprised longitudinal analyses of MRI scans using automated segmentation as well as for five matched paired samples obtained before and after L19TNF tissue immunophenotyping using imaging mass cytometry and mass spectrometry-based proteomics to characterize immunological and molecular effects of the treatment. RESULTS From 2019 - 2020, we enrolled 20 patients (19 WHO Grade 4 and 1 WHO grade 3) from three centers in Switzerland; tumors of 17 patients (85%) had a prognostically unfavorable unmethylated MGMT promoter status. L19TNF could be safely administered at a dose of 13 µg/kg and we did not observe severe adverse events. The median progression-free survival was 2.0 months and the median overall survival was 10.9 months. Using MRI imaging including perfusion maps, we observed that L19TNF led to treatment-associated tumor necrosis within one week of the treatment. Imaging mass cytometry and proteomics from five matched paired samples obtained before and after L19TNF revealed immunophenotypic and molecular changes in tumor tissue, indicating the induction of an anti-tumor immune response and alterations of multiple non-immunological pathways (transcription, translation, cell cycle, proliferation). CONCLUSION The intravenous administration of L19TNF is safe in patients with recurrent glioblastoma and shows pharmacodynamic effects at the tumor site. Ongoing studies investigate L19TNF in combination with temozolomide-based chemoradiation for patients with newly diagnosed glioblastoma (NCT04443010) and in combination with lomustine for patients at first progression (NCT04573192).

KS01.6.A UCPVAX-GLIO: A PHASE II TRIAL EVALUATING THE IMMUNOGENICITY AND EFFICACY OF AN ANTI-TELOMERASE VACCINE IN PATIENTS WITH NEWLY DIAGNOSED GBM

Abstract BACKGROUND The Telomerase Reverse Transcriptase (TERT) is activated in 85%-90% of cancers, and glioblastomas (GBM) harbor the highest incidence of activating mutations within its promoter (over 85% of patients). This high expression of TERT in cancers and its role in oncogenesis make TERT a very promising tumor antigen for immunotherapy, especially in GBM. UCPvax is a therapeutic vaccine in which two CD4 helper peptides derived from TERT are mixed with the Montanide adjuvant. This phase IIa trial was designed to test the immunogenicity, safety and efficacy of UCPvax in patients with newly diagnosed GBM. PATIENTS AND METHODS In this first cohort of the UCPvax-glio trial (NCT04280848), patients with unmethylated MGMT non-mutated IDH1 GBM were included if they had a Karnofsky Performance status (KPS) ≥ 70%, a steroid treatment &amp;lt; 10mg/ day equivalent prednisone, and lymphocytes count ≥ 0.8 x 109/L. One month after completion of radiation/ temozolomide (TMZ), patients started UCPvax vaccinations on days 1, 8, 15, 29, 36 and 43, then every two months until tumor progression. Patients did not receive any additional cure of TMZ because of the unmethylated MGMT promoter status. Peripheral blood mononuclear cells were collected before treatment, at 1 and 2 months after treatment, and at each vaccination boost. The primary endpoint was the anti-TERT specific CD4 T-cell response at 2 months using IFN-gamma ELISPOT. Secondary endpoints included safety, progression-free survival (PFS) and overall survival (OS). RESULTS All the 31 patients (median age 60-yr old, median KPS 90%) included in this study received at least one vaccination. Vaccinations were given for 4.5 months on average (min 2- max 14). At baseline, only one patient had a pre-existing anti-TERT CD4 T-cell response (3%). After immunizations, de novo induction and/or amplification of an anti-TERT response were found in 29/30 patients (97%). An epitope spread response against other tumor-associated antigens was detected in 12/25 patients (48%). All patients developed local skin reactions (≤ grade 2), 16 patients complained of transient asthenia (≤grade 2), and 13 patients experienced local pain (≤grade 2). No severe (grade 3-4) toxicity was attributable to the vaccination. In the intent-to-treat population (n = 31), the PFS was 8.9 months (95% CI: 7.6-10.6) and the median OS was 17.9 months (95% CI: 16-23). Two years after diagnosis, 26% of the patients were still alive. OS was significantly improved in the patients developing an epitope spread response vs the others (20.8 versus 14.1 months, respectively, p = 0.03). CONCLUSION s: In this population of unmethylated MGMT GBM patients, UCPVax is highly immunogenic and provides an interesting OS rate. These data strongly support the completion of the second ongoing cohort, assessing UCPvax in combination with TMZ for GBM patients with methylated MGMT promoter status.

Leptomeningeal metastases in glioma revisited: incidence and molecular predictors based on postcontrast fluid-attenuated inversion recovery imaging.

Leptomeningeal metastases (LMs) in glioma have been underestimated given their low incidence and the lack of reliable imaging. Authors of this study aimed to investigate the real-world incidence of LMs using cerebrospinal fluid (CSF)-sensitive imaging, namely postcontrast fluid-attenuated inversion recovery (FLAIR) imaging, and to analyze molecular predictors for LMs in the molecular era. A total of 1405 adult glioma (World Health Organization [WHO] grade 2-4) patients underwent postcontrast FLAIR imaging at initial diagnosis and during treatment monitoring between 2001 and 2021. Collected molecular data included isocitrate dehydrogenase (IDH) mutation, 1p/19q codeletion, H3 K27 alteration, and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. LM diagnosis was performed with MRI including postcontrast FLAIR sequences. Logistic regression analysis for LM development was performed with molecular, clinical, and imaging data. Overall survival (OS) was compared between patients with and those without LM. LM was identified in 228 patients (16.2%), 110 (7.8%) at the initial diagnosis and 118 (8.4%) at recurrence. Among the molecular diagnostics, IDH-wildtype (OR 3.14, p = 0.001) and MGMT promoter unmethylation (OR 1.43, p = 0.034) were independent predictors of LM. WHO grade 4 (OR 10.52, p < 0.001) and nonlobar location (OR 1.56, p = 0.048) were associated with LM at initial diagnosis, whereas IDH-wildtype (OR 5.04, p < 0.001) and H3 K27 alteration (OR 3.39, p = 0.003) were associated with LM at recurrence. Patients with LM had a worse median OS than those without LM (16.7 vs 32.0 months, p < 0.001, log-rank test), which was confirmed as an independent factor on multivariable Cox analysis (p = 0.004). CSF-sensitive imaging aids the diagnosis of LM, demonstrating a high incidence of LM in adult gliomas. Furthermore, molecular markers are associated with LM development in glioma, and patients with aggressive molecular markers warrant imaging surveillance for LM.

Treatment benefit in patients aged 80 years or older with biopsy-proven and non-resected glioblastoma is dependent on MGMT promoter methylation status

PurposeGlioblastoma is associated with especially poor outcome in the elderly. It is unclear if patients aged ≥80 years benefit from tumor-specific therapy as opposed to receiving best supportive care (BSC) only.MethodsPatients with IDH-wildtype glioblastoma (WHO 2021), aged ≥80 years, and diagnosed by biopsy between 2010 and 2022 were included. Patient characteristics and clinical parameters were assessed. Uni- and multivariate analyses were performed.Results76 patients with a median age of 82 (range 80–89) and a median initial KPS of 80 (range 50–90) were included. Tumor-specific therapy was initiated in 52 patients (68%). 22 patients (29%) received temozolomide monotherapy, 23 patients (30%) were treated with radiotherapy (RT) alone and 7 patients (9%) received combination therapies. In 24 patients (32%), tumor-specific therapy was omitted in lieu of BSC. Overall survival (OS) was longer in patients receiving tumor-specific therapy (5.4 vs. 3.3 months, p < 0.001). Molecular stratification showed that the survival benefit was owed to patients with MGMT promoter methylation (MGMTpos) who received tumor-specific therapy as opposed to BSC (6.2 vs. 2.6 months, p < 0.001), especially to those with better clinical status and no initial polypharmacy. Patients with unmethylated MGMT promoter (MGMTneg) did not benefit from tumor-specific therapy (3.6 vs. 3.7 months, p = 0.18). In multivariate analyses, better clinical status and MGMT promoter methylation were associated with prolonged survival (p < 0.01 and p = 0.01).ConclusionBenefit from tumor-specific treatment in patients with newly diagnosed glioblastoma aged ≥80 years might be restricted to MGMTpos patients, especially to those with good clinical status and no polypharmacy.

Anti-telomerase vaccine in patients with newly diagnosed, unmethylated MGMT glioblastoma: A phase II study.

2005 Background: TERT, a subunit of the telomerase complex, is largely expressed in almost all cancers. Among those cancers, glioblastomas (GBM) harbor the highest incidence of activating mutations within the TERT promoter (over 85% of patients). This high incidence underlies the potential role of TERT in oncogenesis, and points out TERT as a highly relevant tumor target in GBM. UCPvax is a therapeutic vaccine composed of two CD4 helper peptides derived from TERT, combined with the montanide adjuvant. We conducted a phase IIa trial to test the immunogenicity, safety and efficacy of UCPvax in patients with newly diagnosed GBM. Methods: Key inclusion criteria were: histologically confirmed, non-mutated IDH1 glioblastoma, unmethylated MGMT promoter status, previous treatment with concomitant radiotherapy and temozolomide (TMZ), Karnofsky Performance status (KPS) ≥ 70%, steroids &lt; 10mg/ day equivalent prednisone, and lymphocytes count ≥ 0.8 x 109/L. One month after completion of radiation/TMZ, patients started UCPvax vaccinations on days 1, 8, 15, 29, 36 and 43, then every two months until tumor progression, without additional cure of TMZ. Peripheral blood mononuclear cells were collected before treatment, at 1 and 2 months after treatment and, at each vaccination boost. The primary endpoint was an anti-TERT specific CD4 T-cell response measured ex vivo in peripheral blood using IFN-gamma ELISPOT at 2 months. Secondary endpoints included safety, overall survival (OS) and progression-free survival (PFS). Results: Thirty-one adult patients (median age 60-yr old, median KPS 90%) were included in this study. All patients received at least one vaccination, and vaccinations were given for 4.5 months on average (min 2– max 14). At baseline, only one patient had a pre-existing anti-TERT CD4 T-cell response (3%). After immunizations, de novo induction and/or amplification of an anti-TERT response were found in 29/30 pts (97%). An epitope spread response against other tumor-associated antigens was detected in 12/25 pts (48%). No severe (grade 3–4) toxicity was attributable to the vaccination. All patients developed local skin reactions (≤ grade 2), 16 patients complained of transient asthenia (≤grade 2), and 13 patients experienced local pain (≤grade 2). In the intent-to-treat population (n=31), the PFS was 8.9 months (95% CI: 7.6–10.6) and the median OS was 17.9 months (95% CI: 16–23). Two years after diagnosis, 26 % of the patients were still alive. OS was significantly improved in the patients developing an epitope spread response vs the others (19.3 vs 15.8 months, respectively, p=0.03). Conclusions: UCPVax is highly immunogenic and provides an interesting OS rate in this population of poor prognosis, unmethylated MGMT GBM patients. These data support further clinical studies of UCPvax in GBM patients. Clinical trial information: NCT04280848 .

AHR, a novel inhibitory immune checkpoint receptor, is a potential therapeutic target for chemoresistant glioblastoma.

This study aims to elucidate the mechanism underlying temozolomide resistance in patients with MGMT promoter hypomethylated glioblastoma, which is correlated with poor prognosis. The objective is to identify therapeutic targets and drugs suitable for temozolomide-resistant glioblastoma patients using big data analysis. In this retrospective study, transcriptome sequencing data from 457 glioblastoma patients, multi-omics data, and single-cell sequencing data were employed to assess the expression pattern, prognostic value, and biological functions of AHR in glioblastoma. The HERB database was utilized to screen for AHR-targeted drugs for glioblastoma treatment. Validation of our findings was conducted using multiplex immunofluorescence staining of clinical samples and T cells and tumor cells co-culture models. Our findings demonstrated that patients with MGMT promoter unmethylation did not benefit from postoperative temozolomide chemotherapy due to resistance arising from DNA repair function and tumor immune response. AHR was found to be expressed in immune cells and exhibited an immunomodulatory role in glioblastoma with MGMT promoter unmethylation. AHR was identified as a potential novel inhibitory immune checkpoint receptor, serving as a therapeutic target for temozolomide-resistant glioblastoma. Furthermore, targeting AHR with Semen aesculi markedly enhanced the cytotoxic effect of T cells on glioma cells. In addition to DNA repair function, the tumor immune response plays a pivotal role in temozolomide resistance of glioblastoma. Herbal compounds targeting AHR may offer an effective treatment for temozolomide-resistant glioblastoma.