Author Correction: Vorasidenib and ivosidenib in IDH1-mutant low-grade glioma: a randomized, perioperative phase 1 trial

Isocitrate dehydrogenase-mutant (IDHmut) gliomas are a distinct subset of diffuse gliomas in younger adults, including WHO Grade 2–3 oligodendrogliomas and astrocytomas, as well as a subset of Grade 4 astrocytomas. The recent INDIGO trial demonstrated the efficacy of Vorasidenib (Vora), a targeted mIDH inhibitor, in non-enhancing, treatment-naïve, low-grade (Grade II) IDHmut gliomas, leading to FDA approval in August 2024. However, nearly one-half of patients in the trial demonstrated progression at ~20 months and response rates in MRI contrast-enhancing and/or high-grade gliomas remain limited. This underscores the urgent need to (1) understand sensitivity and resistance mechanisms to Vora and (2) develop salvage therapies for a broader range of IDHmut glioma patients. A major obstacle is the scarcity of clinically relevant, patient-derived IDHmut models, particularly from low-grade gliomas. To address these limitations, we developed NanoGlio, a nanoliter-volume organoid platform, enabling rapid generation of patient-derived IDHmut glioma models and assessment of Vora sensitivity within 14-21 days. We established NanoGlio cultures from five Grade 2, one Grade 3, and four Grade 4 IDHmut cases—three with both enhancing and non-enhancing regions—as well as five IDH wild-type controls. Growth and morphology in NanoGlio varied by WHO grade: low-grade tumors grew slowly with lower cellularity, while high-grade IDHmut tumors proliferated rapidly. Vora induced morphological changes in low-grade and non-enhancing high-grade organoids but increased proliferation in enhancing high-grade organoids. Bulk RNA sequencing showed that NanoGlio recapitulates 15 of the top 20 pathways altered in clinical IDH inhibitor trials, with trends in gene expression changes closely mirroring those observed in patient samples. Vora treatment induced upregulation of neural function- and tumor suppression-associated genes, such as NPTX1, SPOCK2, SEZ6, NR1D1, OPCML and SNAP25, in IDHmut organoids. Future work will incorporate single-cell RNA sequencing to refine differentiation trajectories and uncover resistance mechanisms.

Lower grade gliomas frequently harbor mutations in isocitrate dehydrogenase (IDH), which define biologically distinct tumor subtypes. Although IDH-mutant and IDH-wildtype gliomas share similar histological morphology, they display markedly different metabolic profiles that may be exploited for targeted therapy. In this study, we investigated therapeutic approaches tailored to these metabolic differences. Using capillary electrophoresis–mass spectrometry, we compared the metabolomes of engineered IDH-wildtype and IDH-mutant glioma cell models. IDH-mutant cells exhibited elevated asparagine levels and reduced glutamine and glutamate levels compared with IDH-wildtype cells. These differences were corroborated in vivo by proton magnetic resonance spectroscopy of 130 patients with diffuse gliomas, showing lower glutamine and glutamate in IDH-mutant tumors. Pharmacological depletion of asparagine with L-asparaginase, which converts asparagine to aspartate, preferentially inhibited the growth of IDH-wildtype glioma cells, and this effect was potentiated by inhibition of asparagine synthetase. In contrast, inhibition of glutamate dehydrogenase 1 (GLUD1), the enzyme catalyzing the conversion of glutamate to α-ketoglutarate, selectively suppressed proliferation of IDH-mutant glioma cells by inducing reactive oxygen species accumulation and apoptosis. In vivo, L-asparaginase suppressed tumor growth in xenografted IDH-wildtype gliomas, whereas GLUD1 inhibition significantly reduced tumor growth in IDH-mutant glioma xenografts. These findings reveal distinct amino acid metabolic vulnerabilities defined by IDH mutation status and identify L-asparaginase and GLUD1 inhibition (via R162) as promising, mutation-specific therapeutic strategies. L-asparaginase demonstrated potent antitumor activity against IDH-wildtype gliomas, while GLUD1 inhibition selectively suppressed IDH-mutant gliomas both in vitro and in vivo. These results highlight the clinical potential of targeting amino acid metabolism in gliomas and provide a strong rationale for translating these mutation-specific approaches into future clinical trials.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40478-025-02193-8.

Mutations in isocitrate dehydrogenase ( IDH) 1 are high-frequency events in low-grade glioma and secondary glioblastoma, and IDH1 mutant gliomas are vulnerable to interventions. Metabolic reprogramming is a hallmark of cancer. In this study, comprehensive metabolism investigation of clinical IDH1 mutant glioma specimens was performed to explore its specific metabolic reprogramming in real microenvironment. Massive metabolic alterations from glycolysis to lipid metabolism were identified in the IDH1 mutant glioma tissue when compared to IDH1 wild-type glioma. Of note, tricarboxylic acid (TCA) cycle intermediates were in similar levels in both groups, with more pyruvate found entering the TCA cycle in IDH1 mutant glioma. The pool of fatty acyl chains was also reduced, displayed as decreased triglycerides and sphingolipids, although membrane phosphatidyl lipids were not changed. The lower fatty acyl pool may be mediated by the lower protein expression levels of long-chain acyl-CoA synthetase 1 (ACSL1), ACSL4, and very long-chain acyl-CoA synthetase 3 (ACSVL3) in IDH1 mutant glioma. Lower ACSL1 was further found to contribute to the better survival of IDH1 mutant glioma patients based on the The Cancer Genome Atlas (TCGA) RNA sequencing data. Our research provides valuable insights into the tissue metabolism of human IDH1 mutant glioma and unravels new lipid-related targets.

The discovery of the IDH1 R132H (IDH1 mut) mutation in low-grade glioma and the associated change in function of the IDH1 enzyme has increased the interest in glioma metabolism. In an earlier study, we found that changes in expression of genes involved in the aerobic glycolysis and the TCA cycle are associated with IDH1 mut. Here, we apply proteomics to FFPE samples of diffuse gliomas with or without IDH1 mutations, to map changes in protein levels associated with this mutation. We observed significant changes in the enzyme abundance associated with aerobic glycolysis, glutamate metabolism, and the TCA cycle in IDH1 mut gliomas. Specifically, the enzymes involved in the metabolism of glutamate, lactate, and enzymes involved in the conversion of α-ketoglutarate were increased in IDH1 mut gliomas. In addition, the bicarbonate transporter (SLC4A4) was increased in IDH1 mut gliomas, supporting the idea that a mechanism preventing intracellular acidification is active. We also found that enzymes that convert proline, valine, leucine, and isoleucine into glutamate were increased in IDH1 mut glioma. We conclude that in IDH1 mut glioma metabolism is rewired (increased input of lactate and glutamate) to preserve TCA-cycle activity in IDH1 mut gliomas.

Establishing causal links between genetic polymorphisms and increased heritable risk of developing brain cancer is a major challenge. The non-coding single nucleotide polymorphism rs55705857 (A >G) is associated with a ~6-fold increased risk to develop IDH-mutant low-grade glioma (LGG). The rs55705857 G allele has a minor allele frequency of only ~5% in the general population but is found in ~40% of patients with IDH-mutant LGG and patients carrying risk-alleles are diagnosed on average 7-12 years earlier than those carrying non-risk A alleles. This makes rs55705857 one of the highest reported genetic associations with cancer, comparable with inherited BRCA1 gene mutations and the risk of developing breast cancer or other familial glioma genes such as NF1/2, CDKN2A or p53. To generate a LGG mouse model, we combined clonal activation of IDH1R132H with mutations of Trp53 and Atrx, which resulted in the development of LGG-like brain tumors in 25% of mice. Mutating the highly conserved, orthologous mouse rs55705857 locus to mimic the human risk allele dramatically accelerated tumor development from 463 to 172 days and increased penetrance to 75%. The resulting tumors exhibit elevated R-2-hydroxyglutarate levels, well-differentiated fibrillary neoplastic histology and metabolic rewiring, recapitulating histopathological and molecular hallmarks of human LGG. Mechanistically, we show that the rs55705857 locus resides within a brain-specific enhancer, which shows enhanced activity in IDH-mutant tumors. In addition, we found that the risk allele disrupts OCT2/4 binding, allowing increased interaction with the Myc promoter and increased Myc expression. The hyperactive chromatin status combined with the tissue specificity of this enhancer explains the cooperativity between mutant IDH and rs55705857 and why rs55705857 is associated specifically with IDH-mutant glioma, but not other cancers. Overall, we generated new LGG mouse models, which provide insights into the pathophysiology of this deadly disease and shed light into the heritable predisposition to LGG development.

BackgroundPatients with IDH-mutant gliomas often experience seizures that significantly affect their quality of life and outcome. Seizure activity may be the result of dysregulation of excitatory (glutamate, Glu) and inhibitory (gamma-aminobutyric acid, GABA) neurotransmitters in peritumoral tissue. A non-invasive measurement of Glu (in combination with glutamine, termed Glx) and GABA is feasible with proton magnetic resonance spectroscopy (1H-MRS). The aim of this study was to determine whether IDH-mutant glioma patients with seizures exhibit altered Glx and GABA levels compared to patients without seizures.MethodsWe conducted a prospective study involving 23 glioma patients (15 with, 8 without seizures), who underwent single-voxel 1H-MRS using the MEGA-PRESS sequence. 1H-MRS data were collected from volumes of tissues in the tumor/peritumoral regions and parietal cortex used as control. Metabolite ratios (Glx/Cr, GABA/Cr, Glx/GABA) were analyzed and correlated with seizure presence and other clinical-pathological parameters. Longitudinal 1H-MRS data in a subset of 10 patients were also acquired.ResultsAt first study, the Glx/GABA ratio was significantly higher in the tumor/peritumoral tissue of patients with seizures compared to those without (P = .023). Longitudinal data confirmed this finding, showing consistently elevated Glx/GABA values in patients with seizures. Moreover, patients taking two or more antiseizure medications had significantly higher Glx/GABA ratios and lower GABA/Cr ratios in the peritumoral region.ConclusionGlioma patients with seizures have an altered balance of Glx and GABA in tumor/peritumoral tissue, supporting the hypothesis that neurotransmitter imbalances contribute to seizure activity. 1H-MRS may provide non-invasive biomarkers for identifying neurotransmitter dysregulation in glioma-related epilepsy.

Malignant transformation (MT) is commonly seen in IDH-mutant gliomas. There has been a growing research interest in revealing its underlying mechanisms and intervening prior to MT at the early stages of the transforming process. Here we established a unique pair of matched 3D cell models: 403L, derived from a low-grade glioma (LGG), and 403H, derived from a high-grade glioma (HGG), by utilizing IDH-mutant astrocytoma samples from the same patient when the tumor was diagnosed as WHO grade 2 (tumor mutational burden (TMB) of 3.96/Mb) and later as grade 4 (TMB of 70.07/Mb), respectively. Both cell models were authenticated to a patient’s sample retaining endogenous expression of IDH1 R132H. DNA methylation profiles of the parental tumors referred to LGG and HGG IDH-mutant glioma clusters. The immunopositivity of SOX2, NESTIN, GFAP, OLIG2, and beta 3-Tubulin suggested the multilineage potential of both models. 403H was more prompt to cell invasion and developed infiltrative HGG in vivo. The differentially expressed genes (DEGs) from the RNA sequencing analysis revealed the tumor invasion and aggressiveness related genes exclusively upregulated in the 403H model. Pathway analysis showcased an enrichment of genes associated with epithelial-mesenchymal transition (EMT) and Notch signaling pathways in 403H and 403L, respectively. Mass spectrometry-based targeted metabolomics and hyperpolarized (HP) 1-13C pyruvate in-cell NMR analyses demonstrated significant alterations in the TCA cycle and fatty acid metabolism. Citrate, glutamine, and 2-HG levels were significantly higher in 403H. To our knowledge, this is the first report describing the development of a matched pair of 3D patient-derived cell models representative of MT and temozolomide (TMZ)-induced hypermutator phenotype (HMP) in IDH-mutant glioma, providing insights into genetic and metabolic changes during MT/HMP. This novel in vitro model allows further investigation of the mechanisms of MT at the cellular level.Graphic

Isocitrate dehydrogenase 1 (IDH1) mutations occur in most lower-grade glioma, and not only drive gliomagenesis but are associated with longer patient survival and improved response to temozolomide (TMZ). To investigate the possible causative relationship between these events, we introduced wild-type (WT) or mutant IDH1 into immortalized, untransformed human astrocytes, then monitored transformation status and TMZ response. TMZ-sensitive parental cells exhibited DNA damage (gamma-H2AX foci) and a prolonged G2 cell cycle arrest beginning 3 days after TMZ (100 µM, 3hr) exposure and persisting for greater than 4 days. The same cells transformed by expression of mutant IDH1 exhibited a comparable degree of DNA damage and cell cycle arrest, but both events resolved significantly faster in association with increased, rather than decreased, clonogenic survival. The increases in DNA damage processing, cell cycle progression, and clonogenicity were unique to cells transformed by mutant IDH1, and were not noted in cells transformed by WT IDH1 or an oncogenic form (V12H) of Ras. Similarly these effects were not noted following introduction of mutant IDH1 into Ras-transformed cells or established GBM cells. TMZ-induced DNA double strand breaks are repaired in human cells by the process of homologous recombination (HR), and consistent with this observation, the increased TMZ resistance in mutant IDH1-transformed cells was associated with increased HR. Furthermore, the effects of mutant IDH1 on the response to TMZ could be reversed by the genetic or pharmacologic suppression of the HR DNA repair protein RAD51. These results show that mutant IDH1 drives a unique set of transformative events that indirectly enhance HR and facilitate repair of TMZ-induced DNA damage and TMZ resistance. The results also suggest that inhibitors of HR may be a viable means to enhance TMZ response in IDH1 mutant glioma.

BACKGROUND Seizures and epilepsy affect quality of life and may contribute to tumor progression in glioma patients. Previous studies highlighted potential targets, including IDH mutations and gene expression changes in epileptic and peritumoral tissue. Here, we analyzed gene expression patterns associated with seizures in IDH-mutant gliomas and IDH wild-type glioblastoma (GBM) across a large cohort. METHODS Glioma samples underwent NGS and WTS at Caris Life Sciences (Phoenix, AZ). Gene expression and gene set enrichment analysis (GSEA) (normalized enrichment score reported and FDR < 0.25 considered significant) were compared between epilepsy and non-epilepsy groups, with epilepsy identified by having ICD-10 codes G40 or G41 in the insurance claims data. RESULTS Oligodendroglioma (n = 318, 65.7% epileptic), astrocytoma grade 2/3 (n = 673, 70.4% epileptic), astrocytoma grade 4 (n = 247, 68.8% epileptic), and GBM (n = 4371, 55.6% epileptic) cases were identified. In astrocytomas, MYC targets (NES = 1.91), MTORC1 signaling (NES = 1.37), and DNA and stress response (NES = 1.62) and UV response (NES = 1.52) were enriched in epilepsy, while pathways associated with oxidative phosphorylation (NES = -4.07), fatty acid metabolism (NES = -2.02), and protein secretion (NES = -2.01) were enriched in the non-epileptic group. In GBM, pathways involved in cell growth, division, metabolism, and stress regulation—including MYC targets (NES = 2.15), mTOR signaling (NES = 1.62), and the G2/M checkpoint (NES = 2.03)—were enriched in epilepsy. In the non-epileptic group, pathways for immune activation, tissue remodeling, and cancer progression (e.g., EMS (NES = -2.49) and KRAS signaling (NES = -2.23)) were enriched. The oligodendroglioma cohort showed no significant pathway enrichment by epilepsy status, likely due to minimal underlying biological differences. CONCLUSIONS Gene expression patterns differed by epilepsy status and IDH mutation in glioma. Future studies will explore targets for seizure control and tumorigenesis.

The prognostic and predictive value of O6-methylguanine-DNA methyltransferase promoter (MGMTp) methylation is not well established in isocitrate dehydrogenase (IDH)-mutant gliomas. This study evaluates the survival impact of MGMTp and other clinical, molecular, and radiologic variables in low-grade and high-grade IDH-mutant gliomas. We retrospectively evaluated 520 consecutive adult patients treated for an initial diagnosis of IDH-mutant glioma, of any histological grade, at two large academic institutions. MGMTp methylation was evaluated by methylation-specific polymerase chain reaction (PCR) analysis. Log-rank test and Cox proportional hazards model were applied to evaluate the association of clinical, molecular, and radiological characteristics with overall survival (OS) and progression-free survival (PFS). Median age was 36.6 years; MGMTp was methylated in 70% and unmethylated in 30%. MGMTp methylation was not significantly associated with OS (P = 0.11) or PFS (P = 0.74) on multivariate analyses. Cyclin dependent kinase inhibitor 2A/B (CDKN2A/B) homozygous deletion [HR = 3.26 (1.47, 7.23), P = .006] and an integrated grade 4 classification [HR = 2.08 (1.06, 4.67), P = .048] were strong predictors of OS in astrocytoma, whereas maximal resection [HR = 0.06 (0.01, 0.57), p = 0.016] and radiation [HR = 0.41 (0.18, 0.91), P = .03] were strong prognosticators for PFS in the entire cohort. Maximal resection of the enhancing disease [HR = 0.17 (0.05, 0.96), P = .014] and radiation [HR = 0.47 (0.19, 0.65), P = .046] were strongly associated with PFS in grade 2 and 3 gliomas. MGMTp methylation was not associated with a prognostic or predictive value in our IDH-mutant glioma cohort. CDKN2A/B status and extent of resection were strong predictors of outcomes.

Aim: IDH-mutant lower grade glioma (LGG) has been proven to have a good prognosis. However, its high recurrence rate has become a major therapeutic difficulty. Materials & methods: We combined epigenomic deconvolution and a network analysis on The Cancer Genome Atlas IDH-mutant LGG data. Results: Cell type compositions between recurrent and primary gliomas are significantly different, and the key cell type that determines the prognosis and recurrence risk was identified. A scoring model consisting of four gene expression levels predicts the recurrence risk (area under the receiver operating characteristic curve=0.84). Transcription factor PPAR-α explains the difference between recurrent and primary gliomas. A cell cycle-related module controls prognosis in recurrent tumors. Conclusion: Comprehensive deconvolution and network analysis predict the recurrence risk and reveal therapeutic targets for recurrent IDH-mutant LGG.

High-grade glioma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up

Background: It is well understood that gliomas require vast supply of energy to proliferate, invade and spread. We wished to identify novel biomarkers by comparing normal brain and plasma to high and low grade gliomas using newer techniques in laser ionization mass spectroscopy - precision metabolomics and lipidomics. Methods: Single center IRB approved tissue bank of “normal” brain and plasma (n=6) and IDH wild-type GBM tissue and plamsa (n=29), IDH mutant GBM tissue and plamsa (n=6), Low grade glioma (n=4) tissue and plamsa were analyzed for over 2000 endogenous metbolites and complex lipids. Unbiased clustering and Random Forest plots and pathway analysis were performed with appropriate statsitical analysis (significance p < 0.05). Results: IDH mutant GBM had higher levels of 2-HG, however, plasma 2-HG did not reflect IDH genotype. Changes in glucose and fatty acid utilization were observed in IDH WT and mutant gliomas compared to normal brain tissue. Lipidomics of plasma and tissue of normal and gliomas did not reveal a biomarker reaching statistical significance. Conclusions: We will continue to investigate if plasma and tissue biomarkers including hypotaurine, methionine, branched chain amino acid catabolites and pregnonolone can be used to predict tumor progression, response to treatment and clinical outcomes.

2081 Background: IDH-mutant gliomas are slow-growing infiltrating tumors of astrocytic (AS) or oligodendroglial (OG) origin (WHO grade 2/3). The mutations occur in genes that encode the metabolic enzyme IDH1 or, more rarely, IDH2 and lead to production of 2-hydroxyglutarate (2-HG) that can be measured with optimized in-vivo MRS. Small-molecule IDH inhibitors (IDHi) ivosidenib (inhibits mIDH1 enzyme) and vorasidenib (inhibits mIDH1 and mIDH2 enzymes) showed good tumor penetrance and ~95% 2-HG reduction measured in tumor biopsies. Both ivosidenib and vorasidenib have evidence of responses in tumor growth rate. As volume reductions are often observed, but after a delay of several months, thus an early response biomarker highly desired. The aim of this study was to explore whether MRS measurements of 2-HG can be used to non-invasively monitor response to treatment with IDHmut-inhibiting drugs and compare this response to changes in tumor volume. Methods: 14 patients (Age ≥18y) with a histomolecularly confirmed IDH1 mutated diffuse glioma (AS or OG) received ivosidenib (n = 12) or vorasidenib (n = 2) therapy as part of their routine clinical care. MRI was performed before treatment ( baseline ) and repeated ( follow-up ) with a median on-drug follow-up of 6 months [4, 12 IQR]. Tumors were segmented from FLAIR images in 3D Slicer and volumes were calculated in cm 3 . All MRS data were processed in Osprey with the built-in LCModel fitting module. Comparisons between baseline and follow-up measured metabolite levels were conducted using paired t-tests or (in cases where the normality assumption was not met) non-parametric Wilcoxon tests. Results: We analyzed spectra from 11 patients with both baseline and follow-up sessions. All spectra exhibited characteristic tumor features: reduced total N-acetylaspartate (tNAA) and elevated levels of total choline (tCho), lactate (Lac), and myo-inositol (mI), along with a 2-HG peak at 2.25 ppm that is visibly smaller after treatment. The decrease in 2-HG levels was highly significant (p < 0.001) across all included patients undergoing ivosidenib/vorasidenib therapy, regardless of reference standard. Volumetric assessment revealed tumor growth arrest and a subtle reduction in tumor growth in some individuals. Conclusions: This is the first in-vivo evidence using MRS that ivosidenib/vorasidenib reduces 2-HG. We found that 2-HG levels respond specifically and rapidly to treatment, while volumetric changes manifest slowly and more gradually, consistent with previous studies. This preliminary study suggests that in vivo MRS-derived 2-HG estimates could serve as sensitive and specific biomarkers for monitoring low grade gliomas in vivo in response to small-molecule IDH inhibitor therapy after initiation of treatment. Longitudinal volumetric and radiomic analyses are underway.

Uncontrolled seizures in patients with low grade gliomas have a significant impact on quality of life and morbidity, yet the mechanisms through which these tumors cause seizures remain unknown. Albeit there are multiple features that contribute to tumor related epileptogenesis, IDH mutations are determined to be an independent factor, although the pathogenesis remains poorly understood. Here, we hypothesize that the active metabolite D-2-hydroxyglutarate (D-2-HG) produced by the IDH-mutant enzyme leads to metabolic disruptions in surrounding cortical neurons that consequently promote seizures. We use a complementary study of in vitro cortical cultures and electrographically sorted human cortical tissue from patients (n=5) with IDH-mutant gliomas to test this hypothesis. We demonstrate that D-2-HG leads to increased neuronal spiking activity (p< 0.0001) and promotes a distinct metabolic profile in surrounding neurons and upregulation of mTOR signaling (p< 0.0001), which is consistent in human epileptic cortex compared to peritumoral nonepileptic cortex. Furthermore, increases in neuronal activity are induced by mTOR activation and reversed with mTOR inhibition. Together, our data suggest that metabolic disruptions and mTOR signaling upregulation in the surrounding cortex due to D-2-HG may be a driving event for epileptogenesis in patients with IDH-mutant low grade gliomas.