Mutant Gliomas Research Articles

IDH Mutations in Glioma: Molecular, Cellular, Diagnostic, and Clinical Implications

In 2021, the World Health Organization classified isocitrate dehydrogenase (IDH) mutant gliomas as a distinct subgroup of tumors with genetic changes sufficient to enable a complete diagnosis. Patients with an IDH mutant glioma have improved survival which has been further enhanced by the advent of targeted therapies. IDH enzymes contribute to cellular metabolism, and mutations to specific catalytic residues result in the neomorphic production of D-2-hydroxyglutarate (D-2-HG). The accumulation of D-2-HG results in epigenetic alterations, oncogenesis and impacts the tumor microenvironment via immunological modulations. Here, we summarize the molecular, cellular, and clinical implications of IDH mutations in gliomas as well as current diagnostic techniques.

A multi-center, clinical analysis of IDH-mutant gliomas, WHO Grade 4: implications for prognosis and clinical trial design.

Mutations in the Isocitrate Dehydrogenase (IDH) genes, IDH1 or IDH2, define a group of adult diffuse gliomas associated with a younger age at diagnosis and better prognosis than IDH wild-type glioblastoma. Within IDH mutant gliomas, a small fraction of astrocytic tumors present with grade 4 histologic features and poor prognosis. In molecular studies, homozygous deletion of CDKN2A/B is independently predictive of poor prognosis and short survival. As a consequence, 2021 WHO classification now also recognizes this molecular feature, CDKN2A/B deletion, as sufficient for classifying an astrocytoma as IDH-mutant, WHO Grade 4, regardless of histological grading. Here, we investigate outcomes of patients with WHO Grade 4 IDH-mutant astrocytoma both with and without CDKN2A/B deletion, to compare these groups and evaluate clinical and radiographic factors that contribute to survival. We retrospectively identified 79 patients with IDH-mutant astrocytoma with CDKN2A/B deletion detected at initial diagnosis across five international institutions as well as a comparison group of 51 patients with IDH-mutant, astrocytoma, histologically Grade 4 without detectable CDKN2A/B deletion. We assembled clinical and radiographic features for all patients. We find that CDKN2A/B deletion was associated with significantly worse overall survival (OS; p = 0.0004) and progression-free survival (PFS; p = 0.0026), with median OS of 5.0 years and PFS of 3.0 years, compared to 10.1 and 5.0 years for tumors with a grade 4 designation based only on histologic criteria. Multivariate analysis confirmed CDKN2A/B deletion as a strong negative prognosticator for both OS (HR = 3.51, p < 0.0001) and PFS (HR = 2.35, p = 0.00095). In addition, in tumors with CDKN2A/B deletion, preoperative contrast enhancement is a significant predictor of worse OS (HR 2.19, 95% CI 1.22-3.93, p = 0.0090) and PFS (HR = 1.74, 95% CI = 1.02-2.97, p = 0.0420). These findings underscore the severe prognostic impact of CDKN2A/B deletion in IDH-mutant astrocytomas and highlight the need for further refinement of tumor prognostic categorization. Our results provide a key benchmark of baseline patient outcomes for therapeutic trials, underscoring the importance of CDKN2A/B status assessment, in addition to histologic grading, in clinical trial design and therapeutic decision-making for IDH-mutant astrocytoma patients.

Symptom management in isocitrate dehydrogenase mutant glioma

Abstract According to the 2021 World Health Organization classification of CNS tumors, gliomas harboring a mutation in isocitrate dehydrogenase (mIDH) are considered a distinct disease entity, typically presenting in adult patients before the age of 50 years. Given their multiyear survival, patients with mIDH glioma are affected by tumor and treatment-related symptoms that can have a large impact on the daily life of both patients and their caregivers for an extended period of time. Selective oral inhibitors of mIDH enzymes have recently joined existing anticancer treatments, including resection, radiotherapy, and chemotherapy, as an additional targeted treatment modality. With new treatments that improve progression-free and possibly overall survival, preventing and addressing daily symptoms becomes even more clinically relevant. In this review we discuss the management of the most prevalent symptoms, including tumor-related epilepsy, cognitive dysfunction, mood disorders, and fatigue, in patients with mIDH glioma, and issues regarding patient’s health-related quality of life and caregiver needs in the era of mIDH inhibitors. We provide recommendations for practicing healthcare professionals caring for patients who are eligible for treatment with mIDH inhibitors.

VALIDATION OF 2HG-TARGETTED MR SPECTROSCOPY FOR IDENTIFYING IDH-MUTANT GLIOMAS

Abstract AIMS Diffuse gliomas, the most common adult primary brain tumour, are classified by their histological and molecular characteristics and genetic profile. Isocitrate dehydrogenase (IDH) mutant gliomas correlate with longer mean survival and progression-free survival time. In tumour cells, IDH mutations lead to metabolic changes and the production of oncometabolite 2-hydroxyglutarate (2HG). MR spectroscopy (MRS) can assess metabolic changes in disease states in-vivo and non-invasively. In this study, we demonstrate a validation pathway for two advanced MRS methods to be used as IDH-mutation biomarkers in clinic. METHOD Simulated, phantom, and healthy volunteer experiments were performed to optimise and validate three MRS sequences tuned for measuring 2HG. A PRESS sequence was used with TR/TE of 2500/97 ms aiming at the 2HG peaks around 2.25 ppm. An edited PRESS sequence, named MEGA-PRESS, tailored to 2HG 4.02 ppm peak was used with TR/TE of 3000/68 ms, 128 averages, and with editing pulses at 1.9 and 7.5 ppm. A long TE semi-LASER MRS sequence, with improved voxel localisation, was also used (TR/TE: 2500/110 ms). RESULTS Simulations were performed to find optimised sequence parameters and to develop basis sets for analysing the phantom and healthy volunteer acquisitions. Tumour-mimicking phantoms with variable concentrations of 2HG and cystathionine were created and validated with 800 MHz NMR spectroscopy. Phantoms were then used to assess the sensitivity and specificity of the MRS for 2HG and cystathionine. MEGA-PRESS proved Synthetic in-vivo 2HG spectra, combined from healthy volunteers and simulated or phantom-2HG spectra, were used to assess the spectral quality needed to reliably measure 2HG. CONCLUSION MEGA-PRESS proved to be the most robust MRS method and demonstrated accurate and precise measurement of phantom and synthetic 2HG with acceptable SNR. Clinical validation of the technique will need to be performed on LGG patient population, and the overall accuracy will be compared with patient IDH mutation status.

Fractal dimension and lacunarity measures of glioma subcomponents are discriminative of the grade of gliomas and IDH status.

Since the overall glioma mass and its subcomponents-enhancing region (malignant part of the tumor), non-enhancing (less aggressive tumor cells), necrotic core (dead cells), and edema (water deposition)-are complex and irregular structures, non-Euclidean geometric measures such as fractal dimension (FD or "fractality") and lacunarity are needed to quantify their structural complexity. Fractality measures the extent of structural irregularity, while lacunarity measures the spatial distribution or gaps. The complex geometric patterns of the glioma subcomponents may be closely associated with the grade and molecular landscape. Therefore, we measured FD and lacunarity in the glioma subcomponents and developed machine learning models to discriminate between tumor grades and isocitrate dehydrogenase (IDH) gene status. 3D fractal dimension (FD3D) and lacunarity (Lac3D) were measured for the enhancing, non-enhancing plus necrotic core, and edema-subcomponents using preoperative structural-MRI obtained from the The Cancer Genome Atlas (TCGA) and University of California San Francisco Preoperative Diffuse Glioma MRI (UCSF-PDGM) glioma cohorts. The FD3D and Lac3D measures of the tumor-subcomponents were then compared across glioma grades (HGGs: high-grade gliomas vs. LGGs: low-grade gliomas) and IDH status (mutant vs. wild type). Using these measures, machine learning platforms discriminative of glioma grade and IDH status were developed. Kaplan-Meier survival analysis was used to assess the prognostic significance of FD3D and Lac3D measurements. HGG exhibited significantly higher fractality and lower lacunarity in the enhancing subcomponent, along with lower fractality in the non-enhancing subcomponent compared to LGG. This suggests that a highly irregular and complex geometry in the enhancing-subcomponent is a characteristic feature of HGGs. A comparison of FD3D and Lac3D between IDH-wild type and IDH-mutant gliomas revealed that mutant gliomas had ~2.5-fold lower FD3D in the enhancing-subcomponent and higher FD3D with lower Lac3D in the non-enhancing subcomponent, indicating a less complex and smooth enhancing subcomponent, and a more continuous non-enhancing subcomponent as features of IDH-mutant gliomas. Supervised ML models using FD3D from both the enhancing and non-enhancing subcomponents together demonstrated high-sensitivity in discriminating glioma grades (~97.9%) and IDH status (~94.4%). A combined fractal estimation of the enhancing and non-enhancing subcomponents using MR images could serve as a non-invasive, precise, and quantitative measure for discriminating glioma grade and IDH status. The combination of 2-hydroxyglutarate-magnetic resonance spectroscopy (2HG-MRS) with FD3D and Lac3D quantification may be established as a robust imaging signature for glioma subtyping.

Spark in the darkness: Discovering action potentials in brain tumors

Gliomas exhibit significant molecular diversity and poor prognosis. In this issue of Cancer Cell, Curry etal. apply Patch-seq on human glioma samples uncovering hybrid cells with glial and neuronal features, capable of firing action potentials in isocitrate dehydrogenase mutant gliomas. These findings highlight the importance of neural features in tumor biology and progression.

Hexosaminidase B-driven cancer cell-macrophage co-dependency promotes glycolysis addiction and tumorigenesis in glioblastoma

Glycolytic metabolic reprogramming in cancer is regulated by both cancer intrinsic variations like isocitrate dehydrogenase 1 (IDH1) status and non-cancerous microenvironment components like tumor associated macrophages (TAMs). However, the detailed mechanism remains elusive. Here, we identify hexosaminidase B (HEXB) as a key regulator for glycolysis in glioblastoma (GBM). HEXB intercellularly manipulates TAMs to promote glycolysis in GBM cells, while intrinsically enhancing cancer cell glycolysis. Mechanistically, HEXB elevation augments tumor HIF1α protein stability through activating ITGB1/ILK/YAP1; Subsequently, HIF1α promotes HEXB and multiple glycolytic gene transcription in GBM cells. Genetic ablation and pharmacological inhibition of HEXB elicits substantial therapeutic effects in preclinical GBM models, while targeting HEXB doesn’t induce significant reduction in IDH1 mutant glioma and inhibiting IDH1 mutation-derived 2-hydroxyglutaric acid (2-HG) significantly restores HEXB expression in glioma cells. Our work highlights a HEXB driven TAMs-associated glycolysis-promoting network in GBM and provides clues for developing more effective therapies against it.

Association of immunoglobulin E levels with glioma risk and survival.

Previous epidemiologic studies have reported an association of serum immunoglobulin E (IgE) levels with reduced glioma risk, but the association between IgE and glioma prognosis has not been characterized. This study aimed to examine how sex, tumor subtype, and IgE class modulate the association of serum IgE levels with glioma risk and survival. We conducted a case-control study using participants from the University of California, San Francisco Adult Glioma Study (1997-2010). Serum IgE levels for total, respiratory and food allergy were measured in adults diagnosed with glioma (n=1319) and cancer-free controls (n=1139) matched based on age, sex, and race and ethnicity. Logistic regression was adjusted for patient demographics to assess the association between IgE levels and glioma risk. Multivariable Cox regression adjusted for patient-specific and tumor-specific factors compared survival between the elevated and normal IgE groups. All statistical tests were 2-sided. Elevated total IgE was associated with reduced risk of IDH-wildtype (RR=0.78, 95% CI: 0.71-0.86) and IDH-mutant glioma (RR=0.73, 95% CI: 0.63-0.85). In multivariable Cox regression, positive respiratory IgE was associated with improved survival for IDH-wildtype glioma (RR=0.79, 95% CI: 0.67-0.93). The reduction in mortality risk was significant in females only (RR=0.75, 95% CI: 0.57-0.98) with an improvement in median survival of 6.9 months (P<.001). Elevated serum IgE was associated with improved prognosis for IDH-wildtype glioma, with a more pronounced protective effect in females than males, which has implications for the future study of IgE-based immunotherapies for glioma.

456P Real-world data of IDH mutant gliomas in Spain, a RETSINE: GEINO study

456P Real-world data of IDH mutant gliomas in Spain, a RETSINE: GEINO study

Valproic acid targets IDH1 mutants through alteration of lipid metabolism

Histone deacetylases (HDACs) have a wide range of targets and can rewire both the chromatin and lipidome of cancer cells. In this study, we show that valproic acid (VPA), a brain penetrant anti-seizure medication and histone deacetylase inhibitor, inhibits the growth of IDH1 mutant tumors in vivo and in vitro, with at least some selectivity over IDH1 wild-type tumors. Surprisingly, genes upregulated by VPA showed no enhanced chromatin accessibility at the promoter, but there was a correlation between VPA-downregulated genes and diminished promoter chromatin accessibility. VPA inhibited the transcription of lipogenic genes and these lipogenic genes showed significant decreases in promoter chromatin accessibility only in the IDH1 MT glioma cell lines tested. VPA inhibited the mTOR pathway and a key lipogenic gene, fatty acid synthase (FASN). Both VPA and a selective FASN inhibitor TVB-2640 rewired the lipidome and promoted apoptosis in an IDH1 MT but not in an IDH1 WT glioma cell line. We further find that HDACs are involved in the regulation of lipogenic genes and HDAC6 is particularly important for the regulation of FASN in IDH1 MT glioma. Finally, we show that FASN knockdown alone and VPA in combination with FASN knockdown significantly improved the survival of mice in an IDH1 MT primary orthotopic xenograft model in vivo. We conclude that targeting fatty acid metabolism through HDAC inhibition and/or FASN inhibition may be a novel therapeutic opportunity in IDH1 mutant gliomas.

The effects of BMP2 and the mechanisms involved in the invasion and angiogenesis of IDH1 mutant glioma cells

PurposeThis study investigated the effect of an isocitrate dehydrogenase 1 (IDH1) mutation (mutIDH1) on the invasion and angiogenesis of human glioma cells.MethodsDoxycycline was used to induce the expression of mutIDH1 in glioma cells. Transwell and wound healing assays were conducted to assess glioma cell migration and invasion. Western blotting and cell immunofluorescence were used to measure the expression levels of various proteins. The influence of bone morphogenetic protein 2 (BMP2) on invasion, angiogenesis-related factors, BMP2-related receptor expression, and changes in Smad signaling pathway-related proteins were evaluated after treatment with BMP2. Differential gene expression and reference transcription analysis were performed.ResultsSuccessful infection with recombinant lentivirus expressing mutIDH1 was demonstrated. The IDH1 mutation promoted glioma cell migration and invasion while positively regulating the expression of vascularization-related factors and BMP2-related receptors. BMP2 exhibited a positive regulatory effect on the migration, invasion, and angiogenesis of mutIDH1-glioma cells, possibly mediated by BMP2-induced alterations in Smad signaling pathway-related factors.After BMP2 treatment, the differential genes of MutIDH1-glioma cells are closely related to the regulation of cell migration and cell adhesion, especially the regulation of Smad-related proteins. KEGG analysis confirmed that it was related to BMP signaling pathway and TGF-β signaling pathway and cell adhesion. Enrichment analysis of gene ontology and genome encyclopedia further confirmed the correlation of these pathways.ConclusionMutation of isocitrate dehydrogenase 1 promotes the migration, invasion, and angiogenesis of glioma cells, through its effects on the BMP2-driven Smad signaling pathway. In addition, BMP2 altered the transcriptional patterns of mutIDH1 glioma cells, enriching different gene loci in pathways associated with invasion, migration, and angiogenesis.

The IDH paradox: Meta-analysis of alkylating chemotherapy in IDH-wild type and -mutant lower grade gliomas.

IDH-wild type (-wt) status is a prerequisite for the diagnosis of glioblastoma (GBM); however, IDH-wt gliomas with low-grade or anaplastic morphology have historically been excluded from GBM trials and may represent a distinct prognostic entity. While alkylating agent chemotherapy improves overall survival (OS) and progression-free survival (PFS) for IDH-wt GBM and also IDH-mutant gliomas, irrespective of grade, the benefit for IDH-wt diffuse histologic lower-grade gliomas is unclear. We performed a meta-analysis of randomized clinical trials for World Health Organization (WHO) grades 2-3 gliomas (2009 to present) to determine the effect of alkylating chemotherapy on IDH-wt and -mutant gliomas using a random-effects model with inverse-variance pooling. We identified 6 trials with 1204 patients (430 IDH-wt, 774 IDH-mutant) that evaluated alkylating chemoradiotherapy versus radiotherapy alone, allowing us to perform an analysis focused on the value of adding alkylating chemotherapy to radiotherapy. For patients with IDH-wt tumors, alkylating chemotherapy added to radiotherapy was associated with improved PFS (HR:0.77 [95% CI: 0.62-0.97], P = .03) but not OS (HR:0.87 [95% CI: 0.64-1.18], P = .17). For patients with IDH-mutant tumors, alkylating chemotherapy added to radiotherapy improved both OS (HR:0.52 [95% CI: 0.42-0.64], P < .001) and PFS (HR = 0.47 [95% CI: 0.39-0.57], P < .001) compared to radiotherapy alone. The magnitude of benefit was similar for IDH-mutant gliomas with or without 1p19q-codeletion. Alkylating chemotherapy reduces mortality by 48% and progression by 53% for patients with IDH-mutant gliomas. Optimal management of IDH-wt diffuse histologic lower-grade gliomas remains to be determined, as there is little evidence supporting an OS benefit from alkylating chemotherapy.

The biological significance of tumor grade, age, enhancement, and extent of resection in IDH-mutant gliomas: How should they inform treatment decisions in the era of IDH inhibitors?

The 2016 and 2021 World Health Organization 2021 Classification of central nervous system tumors have resulted in a major improvement in the classification of isocitrate dehydrogenase (IDH)-mutant gliomas. With more effective treatments many patients experience prolonged survival. However, treatment guidelines are often still based on information from historical series comprising both patients with IDH wild-type and IDH-mutant tumors. They provide recommendations for radiotherapy and chemotherapy for so-called high-risk patients, usually based on residual tumor after surgery and age over 40. More up-to-date studies give a better insight into clinical, radiological, and molecular factors associated with the outcome of patients with IDH-mutant glioma. These insights should be used today for risk stratification and for treatment decisions. In many patients with IDH-mutant grades 2 and 3 glioma, if carefully monitored postponing radiotherapy and chemotherapy is safe, and will not jeopardize the overall outcome of patients. With the INDIGO trial showing patient benefit from the IDH inhibitor vorasidenib, there is a sizable population in which it seems reasonable to try this class of agents before recommending radio-chemotherapy with its delayed adverse event profile affecting quality of survival. Ongoing trials should help to further identify the patients that are benefiting from this treatment.

METB-01. EFFECTS OF H3.3G34V MUTATION ON GENOMIC H3K36 AND H3K27 METHYLATION PATTERNS IN ISOGENIC PEDIATRIC GLIOMA CELLS

Abstract BACKGROUND Histone H3.3 mutation (H3F3A) occurs in 50% of cortical pediatric high-grade gliomas (pHGGs). This mutation replaces glycine 34 with arginine or valine (G34R/V), impairing SETD2 activity (H3K36-specific trimethyltransferase). Consequently, reduced H3K36me3 is observed on H3.3G34V nucleosomes relative to wild-type, contributing to genomic instability and driving a distinct gene expression signature associated with tumorigenesis. However, it is not known if this differential H3K36me3 enrichment is due to H3.3G34V mutant protein alone. Therefore, we set to elucidate the effect of H3.3G34V mutant protein in pediatric glioma on H3K36me3, H3K27me3 and H3.3 enrichment in vitro. METHODS Experiments were conducted using an established H3.3G34V mutant patient-derived pediatric high-grade glioma cell line (KNS42), and Histone H3.3 wild-type human astrocytes (NHAs). Lentiviral delivery of a doxycycline-inducible RNAi vector targeted against H3F3A was transduced to KNS42 cells to knock down H3.3G34V protein expression. Cell lines were then compared via ChIP-Seq, Western Blot, proliferation and viability studies. RESULTS We found that the doxycycline-inducible shRNA knockdown of mutant H3F3A encoding the H3.3G34V protein resulted in loss of H3.3G34V enrichment and increased H3K36me3 enrichment throughout the genome. After knockdown, H3.3G34V enrichment was preserved at loci observed to have the greatest H3.3G34V and H3K36me3 enrichment prior to knockdown. Induced expression of mutant H3.3G34V protein in vitro was insufficient to induce genomic H3K36me3 enrichment patterns observed in H3.3G34V mutant glioma cells. We also observed strong co-enrichment of H3.3G34V and wild-type H3.3 protein, as well as greater H3K27me3 enrichment, in cells expressing H3.3G34V. CONCLUSIONS Our study demonstrates the effects of H3.3G34V mutant protein on genomic H3K36me3, H3K27me3 and H3.3 enrichment patterns in isogenic cell lines. Further studies examining the impact of theses findings are therefore underway.

Glioma monitoring via longitudinal intracranial cerebrospinal fluid cell-free DNA.

2053 Background: Current methods for glioma treatment response assessment are limited. This study aimed to assess the technical and clinical feasibility of molecular profiling using intracranial CSF from patients with gliomas during their disease course. Methods: Adults with gliomas were recruited for longitudinal intracranial CSF collection using 1) Ommaya reservoirs, from which CSF would be sampled on at least two separate occasions, or 2) CSF collection from other clinically indicated CSF access devices, such as ventriculoperitoneal (VP) shunts. Patients were followed until their last visit or present time for ongoing participants. For this initial cfDNA feasibility study, CSF was collected from Ommaya reservoirs in four patients and from an existing VP shunt in one patient. cfDNA was then extracted and analyzed using two sequencing platforms, PredicineCARE for cancer variant profiling and PredicineSCORE for low-pass whole genome sequencing (LP-WGS). This analysis generated genomic aberration profiles and genome-wide copy number burden (CNB) score. Results: Five patients (2 females, 3 males; median age: 40 years, range 32-64 years) underwent longitudinal intracranial CSF collection via Ommaya reservoirs (n=4) or VP shunt (n=1). In total, thirty-five CSF samples were obtained (median volume: 3.80 mL; 0.5-5 mL), with 30 samples (85.7%) yielding sufficient cfDNA for variant profiling and LP-WGS. Our initial findings suggest that tumor fraction increased by 6.28x and 2.87x with radiographic progression in two patients. Tumor fraction decreased by 0.08x and 0.04x in two patients with paired immediate pre-versus-post chemoradiation samples. Despite ongoing pseudoprogression in one patient, tumor fraction decreased to unmeasurable levels from a post-resection baseline of 0.26. Patient-specific tumor-associated variant allelic frequencies (VAFs), including TP53, PTEN, TERT, and CDKN2A/B, decreased within individual patients after resection and chemoradiation. In two patients with isocitrate dehydrogenase (IDH) mutant gliomas, decreasing IDH1 VAF after resection correlated with decreased CSF D-2-hydroxyglutarate (D-2-HG) levels (0.64x and 0.62x, respectively, for the first patient, and 0.01x and 0.07x for the other patient). Both CSF IDH1 VAF and CSF D-2-HG increased in the patient who had radiographic progression (2.56x and 9.21x, respectively). Moreover, CNB decreased below the limit of quantification during treatment and increased above the limit at progression. Conclusions: Longitudinal CSF cfDNA can feasibly be obtained via CSF access devices in patients with gliomas during their disease course. Ongoing studies will evaluate hypotheses generated in this case series regarding how longitudinal CSF cfDNA could be utilized to sensitively detect changes in disease burden. Clinical trial information: NCT04692337 ; NCT04692324 .

A phase II, open label, single arm study of nivolumab for recurrent or progressive IDH mutant gliomas with prior exposure to alkylating agents.

A phase II, open label, single arm study of nivolumab for recurrent or progressive IDH mutant gliomas with prior exposure to alkylating agents.

Retrospective study of ivosidenib for patients with recurrent IDH mutant gliomas.

2040 Background: IDH mutant gliomas are the most common primary malignant brain tumors in adults under the age of 50 and accounts for approximately 12% of all glioma diagnoses each year. While lower grade gliomas (LGG) encompassing WHO grades II and III are less aggressive than their higher-grade counterparts, treatment is not curative, and most patients develop tumor recurrence in which there are a paucity of effective treatment options. Mutations in IDH1/ 2 occur upwards of 80% of patients with LGG and drive specific epigenetic programs to dysregulate and impair differentiation leading to tumorigenesis. As such, pharmacologic blockage of IDH mutant enzymes is being actively investigated as potential treatment option. Ivosidenib (AG-120), a second-generation IDH inhibitor, is an FDA approved medication for treatment of IDH-mutated acute myeloid leukemia and has demonstrated safety and clinical activity in patients with progressive IDH mutant gliomas. We explored the efficacy of Ivosidenib in IDH mutant gliomas. Methods: We retrospectively analyzed patients with IDHm gliomas treated with ivosidenib in our institution. We included patients with an IDH1 mutation who received at least one cycle of ivosidenib. Data collected included patient demographics, tumor histology, tumor location, grade, 1p/19q co-deletion, MGMT, CDKN2A, TERT, EGFR, P53, PTEN mutational status, prior treatment history, duration of treatment, toxicities, radiographic response, PFS, and OS. Descriptive statistics were used to summarize patients' characteristics. The distribution of mPFS was estimated by the Kaplan-Meier method. Results: Between April 2010 and December 2023, we identified 33 patients that received ivosidenib. 7 patients received ivosidenib in combination with bevacizumab, 3 patients received ivosidenib in combination with radiation, and 1 patient received ivosidenib and nivolumab. The median age was 52 (range 31-81). 21 (63%) were male. The median lines of medical therapy and radiation/surgery prior to starting ivosidenib were 3.03(range 0-6) and 1.5(range 0-4), respectively. 27(81%) were grade 2, 5(15%) were grade 3, and 1(3%) were grade 4. 19(57%) had 1p/19q co-deletion. As of 12/31/2023, 48%(16) patients were alive. The median PFS was 7.52 months (1-26) and median OS 12.7 months (3-25). 11(33%) patients experienced partial response (PR), 20(60%) experienced stable disease (SD) and 2(6%) demonstrated progressive disease (PD) at 12-week assessment. Nine patients experienced adverse events: grade 1 fatigue (3), grade 1 diarrhea (1), grade 2 fever (1), grade 2 weakness (1), and grade 3 confusion (1). One patient experienced grade 4 lobar hemorrhage thought to be related to concurrent bevacizumab use. Conclusions: Treatment with Ivosidenib therapy was associated with a manageable safety profile. In a subset of patients, there was disease stabilization in heavily pre-treated recurrent IDH mutant gliomas.

NFKBIA deletions reshape the epigenome antithetical to the IDH mutation and indication of prognosis in diffuse gliomas.

2083 Background: Genetic alterations help predict the clinical behavior of diffuse gliomas, but some variability remains uncorrelated. The NFKBIA gene at 14q13.2 encodes IkBa, a protein that regulates the activity of NF-kB in the cytoplasm. Evidence that, in chromatin, nuclear NFKBIA dynamically interacts with histones H2A and H4 to regulate polycomb-dependent transcriptional repression and, thus, stem cell maturation and lineage specification and our characterization of NFKBIA as a tumor suppressor in glioblastoma prompted our investigation of the relationship of NFKBIA deletions to other genetic markers, alterations in the methylome, and the clinical course of gliomas. Methods: We analyzed the genetic profiles of 2,343 WHO grade 2 to 4 diffuse gliomas in multiple clinically well-characterized patient populations, including national randomized phase III consortium trial RTOG 9802, to determine whether incorporation of NFKBIA deletions could enhance the prognostic value of current molecular descriptions. Results: We demonstrate that haploinsufficient deletions of NFKBIA display distinct patterns of occurrence in relation to other genetic markers, including driver mutations IDH, TERT, ATRX, and PTEN, 1p19q codeletion, and CDKN2A/B deletion, and are disproportionally present at recurrence. NFKBIA haploinsufficiency is associated with unfavorable patient outcomes, independent of genetic and clinicopathologic predictors. NFKBIA deletions reshape the DNA and histone methylome antipodal to the IDH mutation. The methylome changes facilitated through NFKBIA deletions engender a transcriptome landscape partly reminiscent of H3K27M mutant pediatric gliomas and are highly enriched for neural stem cell and neurogenesis genes bearing repressive H3K27 marks. Our findings imply that the NFKBIA deletion in adult gliomas and the H3K27M mutation in pediatric diffuse midline gliomas define aggressive disease subtypes that may share an epigenetic state reflecting a common PRC2 loss-of-function phenotype antipodal to the quasi PRC2 gain-of-function phenotype of IDH mutant gliomas and their favorable clinical course. Lower-grade gliomas harboring NFKBIA deletions behave much like high-grade gliomas. In IDH mutant gliomas, NFKBIA deletions are common in tumors with a clinical course similar to that of IDH wildtype tumors. A sparse, easily interpretable, and externally validated nomogram model for estimating individual patient survival in IDH mutant gliomas, incorporating NFKBIA deletion and current best-established genetic and clinicopathologic factors, confirms that NFKBIA deletions predict comparatively brief survival. Conclusions: NFKBIA haploinsufficiency aligns with distinct epigenome changes, portends a poor prognosis, and should be incorporated into clinical models predicting the disease fate of diffuse gliomas.

Isocitrate Dehydrogenase Inhibitors in Glioma: From Bench to Bedside.

Isocitrate dehydrogenase (IDH) mutant gliomas are a primary malignancy of the central nervous system (CNS) malignancies, most commonly affecting adults under the age of 55. Standard of care therapy for IDH-mutant gliomas involves maximal safe resection, radiotherapy, and chemotherapy. However, despite good initial responses to multimodality treatment, recurrence is virtually universal. IDH-mutant gliomas represent a life-limiting prognosis. For this reason, there is a great need for novel treatments that can prolong survival. Uniquely for IDH-mutant gliomas, the IDH mutation is the direct driver of oncogenesis through its oncometabolite 2-hydroxygluterate. Inhibition of this mutated IDH with a corresponding reduction in 2-hydroxygluterate offers an attractive treatment target. Researchers have tested several IDH inhibitors in glioma through preclinical and early clinical trials. A phase III clinical trial of an IDH1 and IDH2 inhibitor vorasidenib yielded promising results among patients with low-grade IDH-mutant gliomas who had undergone initial surgery and no radiation or chemotherapy. However, many questions remain regarding optimal use of IDH inhibitors in clinical practice. In this review, we discuss the importance of IDH mutations in oncogenesis of adult-type diffuse gliomas and current evidence supporting the use of IDH inhibitors as therapeutic agents for glioma treatment. We also examine unresolved questions and propose potential directions for future research.

Clinical Course after Carmustine Wafer Implantation for Newly Diagnosed Adult-type Diffuse Gliomas; A controlled propensity matched analysis of a single center cohort.

It remains unclear whether combining carmustine wafer (CW) implantation with the standard treatment for adult-type diffuse gliomas is safe and has a prognostic impact. This study aimed to investigate the prognostic value and safety of CW implantation. Adult patients with IDH-wild-type and -mutant gliomas, grades 3-4 treated with surgical resection, radiotherapy, and temozolomide chemotherapy between 2013 and 2023 were surveyed. CWs were implanted except in cases of intraoperative wide ventricle opening or marked preoperative brain swelling. For survival analyses, a case-matched dataset based on propensity score matching (PSM), including multiple factors (patient background, diagnosis, and extent of resection) was generated. Progression-free survival (PFS), overall survival (OS), and frequency of complications of CW implantation (brain edema, infection, and cerebrospinal fluid leakage) were compared between the CW and non-use groups. In total, 127 patients (75 in the CW use group and 52 in the non-use group) were enrolled. Regardless of stratification, no significant differences in PFS and OS were observed between the CW use and non-use groups. The frequency of postoperative brain edema was significantly higher in the CW use group than in the non-use group. An adjusted dataset containing 41 patients in the CW use and nonuse groups was generated. Even after PSM, CW implantation had no prognostic effect. CW implantation with standard treatment demonstrated little beneficial effect for the present strategy of CW use.