IDH1 Mutations Research Articles

Outcomes of patients with acute myeloid leukemia and bone marrow fibrosis.

The outcomes of patients with acute myeloid leukemia (AML) and bone marrow fibrosis (MF) are not well defined. The study objectives were to evaluate the degrees of MF in AML, and corresponding response rates and outcomes. We performed a retrospective review of 2302 patients with AML. We annotated the clinical and molecular characteristics, response to therapy, and survival outcomes of patients with bone marrow fibrosis. Overall, 492 patients (21.4%) had a reported microscopic evaluation of MF: 344 (69.9%) had MF grade 0-1 and 148 (30.1%) had MF grade 2-3. Patients with MF 2-3 had a higher proportion of complex cytogenetics (39.2% vs. 24.7%, p = 0.002) JAK2 mutations (25.7% vs. 18%, p = 0.07) and lower proportion of IDH2 (16.9% vs. 25.9%, p = 0.03) and CEBPA (15.5% vs. 27.6%, p = 0.006) mutations. 64% were treated with low-intensity chemotherapy (LIT) and 36.1% with intensive chemotherapy (IT). The complete remission (CR)/CR with incomplete count recovery (CRi) rates were 63.5% with IC versus 37.9% with LIT (p = 0.007). In patients aged 60 or older 4-week mortality was 12.5% with IC vs. 9.3% with LIT (p = 0.8). The median overall survival (OS) was 14.2 with MF 0-1 versus 7.5 months with MF 2-3 (p < 0.005). In patients aged 60 or older with MF 2-3 median OS was 6.5 months with IT versus 7.0 months with LIT (p = 0.19). In a multivariate analysis, grade 2-3 MF (HR 2.0, 95%CI 1.59-2.51) was the strongest prognostic factor for survival. In summary, grade 2-3 MF in AML is associated with worse outcomes.

RETROSPECTIVE ANALYSIS OF GLIOBLASTOMA OUTCOMES

Background Glioblastoma (GBM) is one of the most aggressive brain cancers, with a median overall survival (OS) of about 15 months. This retrospective study focuses on 144 GBM cases treated over 12 years in our clinic in Romania, analyzing factors affecting progression-free survival (PFS) and OS, including genetic markers and treatment modalities. Methods This study involved patients treated between 2012 and 2024 at the National Institute of Neurology and Neurovascular Diseases in Bucharest. The cohort included 144 patients, with variables such as age, gender, tumor location, IDH mutation status, Karnofsky Performance Status (KPS), and genetic markers (MGMT methylation and EGFR amplification) analyzed. Survival outcomes were evaluated using Kaplan-Meier curves and log-rank tests. Results - Patient Demographics: The cohort included 64 males (44.4%) and 80 females (55.6%) with a mean age of 60.7 years. - Tumor Characteristics: The most common tumor location was the frontal lobe (31.9%), followed by multilobular GBM (26.3%). Right-side tumors were more prevalent (51.3%). - Genetic Markers: MGMT promoter was methylated in 46 patients (31.9%), and EGFR was amplified in 76 patients (52.7%). - Treatment Modalities: 105 patients (72.9%) received chemotherapy with temozolomide (TMZ), and 116 patients (80.5%) underwent radiotherapy. - Survival Outcomes: Median PFS was 5 months, and median OS was 8.5 months. Kaplan-Meier survival curves indicated significantly increased OS in patients with MGMT methylation undergoing chemotherapy (p&lt;0.005) and radiotherapy (p&lt;0.005). Similarly, OS was significantly higher in patients without EGFR amplification receiving chemotherapy (p&lt;0.005) and radiotherapy (p&lt;0.005). Conclusion The study emphasizes the importance of MGMT methylation and EGFR amplification in predicting survival outcomes in GBM patients. Immediate postoperative adjuvant therapy significantly improves PFS and OS. The findings underscore the need for coordinated care and timely access to adjuvant therapies to enhance survival rates in GBM patients. Second surgical interventions also showed a survival benefit, highlighting their potential role as salvage therapy in recurrent GBM cases.

IDH1 R132H and TP53 R248Q Mutations Modulate Glioma Cell Migration and Adhesion on Different ECM Components

Mutations in IDH1 and TP53 have a significant impact on glioma prognosis and progression; however, their roles in tumor cell invasion in terms of interactions with particular components of the extracellular matrix (ECM) are still unclear. Using gene editing protocol based on CRISPR-Cas 9 with cytidine deaminase, we introduced point mutations into U87MG glioblastoma cells to establish modified cell lines with heterozygous IDH1 R132H, homozygous TP53 R248Q and heterozygous IDH1 R132H, homozygous TP53 R248Q genotypes. A comparative study of cell migration on major ECM components was carried out by high-content microscopy. IDH1 R132H mutation introduced to U87MG glioblastoma cells was shown to decrease the migration speed on Matrigel and collagen IV substrates compared to the wild-type. This data were supported by cell adhesion quantification via the lateral shift assay performed by atomic force microscopy (AFM). TP53 R248Q mutation increased cell adhesion to various substrates and significantly promoted cell migration on hyaluronic acid and chondroitin sulfate but did not change the migration rates on laminin and collagens IV and I. A double-mutant genotype produced by consequently introducing IDH1 R132H and TP53 R248Q to parental glioblastoma cells was characterized by the highest migration among all the cell lines, with particularly faster motility on chondroitin sulfate. These findings underscore the complex interactions between glioma cells, with the most important driver mutations and specific ECM components regulating cancer cell migration, offering valuable insights for potential therapeutic targets in glioma treatment.

OXPHOS mediators in acute myeloid leukemia patients: Prognostic biomarkers and therapeutic targets for personalized medicine.

Despite significant advances in comprehending its tumorigenic role, the prognostic and therapeutic potential of targeting oxidative phosphorylation (OXPHOS) in acute myeloid leukemia (AML) remain obscure. The prognostic value of ~ 200 mitochondrial/OXPHOS genes as candidate biomarkers was examined in AML patients over ~ 10 years follow-up using Kaplan-Meier and Cox regression analyses. Furthermore, the transcript levels of the assessed markers were inspected in healthy bone marrow tissues and the dependencies of AML cells on the assessed genes were examined. Elevated levels of NADH:ubiquinone oxidoreductase subunit A6 (NDUFA6), succinate dehydrogenase complex flavoprotein subunit A (SDHA), solute carrier family 25 member 12 (SLC25A12), electron transfer flavoprotein subunit beta (ETFB), carnitine palmitoyltransferase 1A (CPT1A) and glutathione peroxidase 4 (GPX4) were associated with poor overall survival of AML patients. SLC25A12, ETFB and CPT1A were overexpressed in AML compared to healthy tissues. Cytochrome B5 type A (CYB5A)high, SLC25A12high and GPX4high AML patients displayed higher levels of circulating and engrafted blasts compared to low-expressing cohorts. NPM1 and SRSF2 mutations were frequent in SDHAlow and CPT1Alow AML patients respectively. FLT3-ITD, NPM1 and IDH1 mutations were prevalent in CPT1Ahigh AML patients. FLT3-ITD AMLs were more dependent on OXPHOS. This study identifies NDUFA6 and SDHA as novel companion prognostic biomarkers which might present a rational strategy for personalized therapy of AML patients.

The prognostic impact of CDKN2A/B hemizygous deletions in IDH-mutant glioma.

Homozygous deletions of CDKN2A/B are known to predict poor prognosis in gliomas, but the impact of hemizygous deletions is less clear. This study aimed to evaluate the prognostic significance of hemizygous CDKN2A/B deletions in IDH-mutant low-grade astrocytomas and oligodendrogliomas. Tissue samples diagnosed as astrocytoma, IDH-mutant and oligodendroglioma, IDH-mutant, 1p/19q co-deleted CNS WHO grade 2 and 3 were collected from the archives of the Institute of Neuropathology in Heidelberg. DNA methylation analysis was performed on formalin-fixed paraffin-embedded (FFPE) samples. Evaluation of the CDKN2A/B locus was performed by visual inspection of copy-number plots derived from methylation-array data for each case. Hemizygous and homozygous losses were assessed in relation to whole chromosomal or larger segmental losses and gains in the chromosomal profile. Survival probabilities were assessed using the Kaplan-Meier method. A total of 334 low-grade glioma cases were identified, including 173 astrocytomas and 161 oligodendrogliomas. Hemizygous deletions in CDKN2A/B (37/173 in astrocytomas, 15/161 in oligodendrogliomas) did not confer significantly worse survival outcomes compared to CDKN2A/B wildtype cases in neither low grade astrocytoma (log-rank p= 0.2556; HR 2.29, 95% CI [0.76; 6.40], p= 0.135) nor oligodendroglioma (log-rank p= 0.2760; HR 0.17; 95% CI [0.01; 5.05]; p= 0.305), regardless of CNS WHO grade, which was further demonstrated on a subgroup of astrocytoma, IDH mutant CNS WHO 4 cases (log-rank p= 0.1680; HR 4.55, 95% CI [0.88; 24.51], p= 0.0689). Hemizygous CDKN2A/B deletions do not significantly worsen OS or PFS in IDH-mutant astrocytomas and oligodendrogliomas, CNS WHO grade 2 and 3.

IMMU-13. TRANS-SPECIES STUDY OF IDH-MUTANT REPLICATION-REPAIR DEFICIENT HIGH-GRADE GLIOMAS (RRD-HGG) AND RESPONSE TO COMBINED TARGETED AND IMMUNOTHERAPY: AN IRRDC STUDY

Abstract BACKGROUND AND AIMS IDH-mutant gliomas comprise &amp;lt;10% of HGG in children. RRD-HGG comprise 5-10% of childhood HGG, demonstrate high mutation burden (TMB) and respond to immune-checkpoint inhibition (ICI). The impact of RRD within childhood IDH-mutant gliomas, and effective therapeutic options for these patients are not well-established. METHODS Clinical and multi-omic analyses were performed on IDH mut -RRD-HGG registered to the IRRDC and the Toronto glioma taskforce. Tumor development and genomic data were studied from a novel IDH mut -RRD-HGG immunocompetent mouse model. Outcome following ICI and targeted therapy were evaluated. RESULTS RRD was detected in &amp;gt;60% of childhood IDH mut -HGG. IDH1-mutations were detected in 20% of RRD-HGG. All patients with IDH mut -RRD-HGG (n=49) harboured germline variants in MMR genes (CMMRD: 65%, Lynch: 35%). Contrary to sporadic IDH mut -gliomas, &amp;gt;91% were WHO-grades 3/4. Diffuse/multifocal disease involving the frontal lobe was frequent. TMB (median: 28 mutations/Mb) was lower than IDH-wildtype RRD-HGG (p&amp;lt;0.05). POLE/POLD1 mutations were absent. TP53 and ATRX were frequent somatic hits. Copy number changes, particularly CDKN2A/2B loss, were common. IDH-mutation contributed to an immune-suppressed microenvironment, with lower CD8-T-cell infiltration (immunohistochemistry) and tumor-inflammation scores (transcriptome; p&amp;lt;0.05). A novel mouse model (Olig2-Cre+/Msh2LoxP/LoxP/LSL-Idh1R132H/+) demonstrated similar TMB, diffuse cerebral involvement, slower growth, and lesser immune infiltrates as compared with IDH-wildtype RRD-HGG models, and provided opportunity for therapeutic testing. RRD contributed to poor survival in IDHmut-gliomas (p&amp;lt;0.001). Despite hypermutation, ICI monotherapy resulted in inferior survival in IDH mut -RRD-HGG vs IDH-wildtype RRD-HGG (p&amp;lt;0.05). Five patients developed metachronous IDH mut -RRD-HGG while on anti-PD1 treatment for IDH-wildtype RRD-HGG, suggesting intrinsic ICI-resistance. Ivosidenib (IDH-inhibitor) demonstrated objective response in 4/8 IDH mut -RRD-HGG. Furthermore, for IDH mut -RRD-HGG on ICI treatment, the addition of ivosidenib prolonged survival at 12-months in comparison to those without IDH-inhibition (p=0.01) CONCLUSIONS Hypermutant RRD-HGG with IDH1;p.R132H harbour unique immuno-biology and do not respond to anti-PD1 monotherapy. The addition of IDH-inhibition demonstrated favourable responses, supporting need for evaluation of the combination in clinical trials.

RADT-38. CLINICAL, MOLECULAR AND IMAGING FEATURES ASSOCIATED WITH LONG TERM SURVIVAL IN GLIOBLASTOMA PATIENTS

Abstract INTRODUCTION Glioblastoma (GBM) is the most common malignant brain tumor in adults and has poor prognosis despite standard of care treatment. Nevertheless, certain patients surpass survival expectations. This study seeks to identify the clinical, molecular, and imaging characteristics of GBM associated with extended patient survival. METHODS In this retrospective cohort study, we examined records of adult GBM patients (WHO 2016 classification) treated at Thomas Jefferson University Hospital from 2010 to 2023. Exclusion criteria included a preoperative Karnofsky Performance Status (KPS) below 60 and treatment with hypo-fractionated radiation therapy. Patients were categorized into two groups: short-term survivors (STS), who survived less than 36 months from diagnosis, and long-term survivors (LTS), who survived more than 36 months. We reviewed patient charts and pathology reports for comprehensive clinical and molecular data. For radiomics analysis, tumor segmentation was performed using CaPTk software on the initial diagnostic MRI (T1 pre and post-contrast, FLAIR and T2 sequences). The relationship between overall survival of more than three years was analyzed with univariable logistic models for potential predictors using R statistical software. RESULTS Of the cohort of 210 patients, 37 (17.6%) survived beyond three years. The median age at diagnosis was 55 years (range; 29-79) Twenty-two patients were male and 15 were female. Twenty-two percent had IDH mutation and 65% had MGMT methylation. Factors associated with long-term survival included younger age at diagnosis (p =0.007), MGMT hypermethylation (p =0.019), IDH mutation (p=0.001), absence of TERT mutation (p = 0.002), higher average number of adjuvant temozolomide cycles (10 vs. 5; p = 0.005), and smaller volume of enhancing tumor on T1 post-contrast imaging segmentation (p=0.022). But there was no significant difference in FLAIR abnormality or necrotic core volumes between the groups. CONCLUSION In our cohort of GBM patients, patients diagnosed at a younger age, MGMT hypermethylation, IDH mutation, absence of TERT mutation, receiving more cycles of adjuvant temozolomide treatment, and smaller enhancing tumor volume on preoperative T1 post-contrast imaging were associated with longer survival. Future research involving larger cohorts and validation of our findings is needed.

NCOG-30. FACTORS ASSOCIATED WITH COGNITIVE IMPAIRMENT IN LONG-TERM IDH-MUTANT GLIOMA SURVIVORS

Abstract BACKGROUND Cognitive deficits are less frequent in patients with IDH mutant (IDHm) than wild-type glioma at time of diagnosis, but less is known about factors that influence cognition for long-term survivors. We evaluated long-term neuropsychological outcomes of patients with IDHm glioma. METHODS Patients with IDHm glioma who underwent clinical neuropsychological assessment at Massachusetts General Hospital 3+ years after diagnosis were included and compared to a previously published cohort of IDHm patients tested prior to surgery/diagnosis (Wefel et al., 2016). RESULTS Sixty-three patients were included for analysis (54% male; median age 45 [range 21-75], 16 years of education, and 7 years from diagnosis [range 3-28]). Thirty-eight patients (60%) had astrocytoma and 24 (40%) had oligodendroglioma; 28 (44%) were grade 2, 31 (49%) grade 3, and 4 (6%) grade 4. Fifty-five patients (87%) received radiation and 51 (81%) received chemotherapy. Cognitive impairment (defined as Z score ≤-1.5 on at least two tests) was present in 30 patients (48%) and was associated with lower scores in neurologic aspects of quality of life (QoL; p&amp;lt;0.01), grade 3/4 relative to grade 2 (p=0.01), older age (p=0.03), left-sided lateralization (p=0.02), and less education (p=0.01). Prior radiation (p=0.07) and photon relative to proton radiation (p=0.06) trended toward poorer function. Tumor type, disease duration, and extent of resection were not significant factors (p&amp;gt;0.05). Compared to the pre-diagnosis IDHm cohort, impairment was significantly more common on tests of processing speed and language. Learning/memory, executive, and visuospatial function trended toward more frequent impairment but were not significant. Attention had comparable frequency of impairment. CONCLUSIONS In this cohort of IDHm glioma survivors, neurocognitive deficits were common, related to QoL, and associated with some expected clinical factors, but not length of survival. These findings emphasize the need for future research on interventions aimed at supporting patients’ neurocognitive abilities and QoL.

BIOM-32. GENOMIC DETERMINANTS OF DIFFUSELY INFILTRATIVE GLIOMATOSIS CEREBRI PATTERN

Abstract Gliomatosis cerebri (GC), though no longer a distinct pathological entity in WHO 2021, is a unique and aggressive phenotype of diffuse gliomas with extensive and widespread infiltration. GC can present as primary de novo or secondary after treatment. We aimed to study the genomic determinants of GC. We identified 72 GC cases from 2013-2023 at MD Anderson Cancer Center. Cases were confirmed by detailed radiographic review. This included 57 glioblastoma (79%), 13 IDH mutant astrocytoma (18%), 1 IDH mutant oligodendroglioma (1.4%), and 1 high-grade astrocytoma with piloid features (1.4%). 53/72 (73.6%) were primary and 19/72 (26.4%) were secondary GC. We used 40 patients without the GC pattern as controls. Among glioblastoma GC cases and in comparison with controls, mutations in PTEN and EGFR were significantly associated with the GC pattern: 18/57 (32%) vs 3/38 (7.9%), p-value=0.01 and 23/57 (40%) vs 6/38 (16%), p-value=0.013, respectively. This held true in primary but not secondary GC. Out of 20 most commonly mutated genes in GC, mutations in EGFR, TERT, and MDM4 were associated with worse PFS: p-value=0.004, p-value=0.007, p-value=0.013, respectively and mutations in TERT and MDM4, but not EGFR, were associated with worse OS: p-value=0.003, p-value=0.015, respectively. Secondary GC was associated with IDH mutation compared to control non-GC cases: 8/19 (42%) vs 2/40 (5%), p-value=0.001. As expected, IDH mutation was associated with improved PFS, p-value&amp;lt;0.001 and OS, p-value=0.003 in GC. No genes were significantly associated with laterality of GC. We found novel associations between PTEN and EGFR mutations and the GC phenotype and IDH mutation with the occurrence of secondary GC after treatment. While MDM4 is not associated with outcomes in gliomas, we show that MDM4 mutation is associated with poor survival in GC. These findings shed light into molecular basis of GC and need to be further validated in larger studies.

SURG-23. ESTABLISHMENT OF AN APPROPRIATE GLIOMA SURGERY SYSTEM CONSIDERING MOLECULAR AND FUNCTIONAL BOUNDARIES

Abstract Gliomas are invasive tumors and cannot be cured by surgery. But surgical removal has also been proven to affect treatment outcomes. Recent advances in molecular diagnostics have identified IDH mutations, especially in lower grade gliomas, allowing the identification of so-called molecular boundaries. It is conceivable that expanded resection to the molecular border may improve treatment outcome. On the other hand, extended resection may be incompatible with functional preservation. In such cases, it is also important to consider that the impact of surgery on treatment outcome has also been proven to vary by glioma genotype. While total resection has a significant prognostic impact on survival in astrocytomas with IDH mutations, the impact on survival in oligodendrogliomas that are sensitive to chemoradiotherapy and, conversely, in high-grade tumors without IDH mutations is lower than in the former. Therefore, it is important to determine the extent of removal after considering the tumor type. In general, various surgical support devices such as surgical navigation systems, fluorescent diagnosis using 5ALA, intraoperative electrophysiological monitoring, awake functional brain mapping, and intraoperative MRI are applied during glioma surgery. In addition to these, we have developed a surgical system that also focuses on tumor subtypes by introducing preoperative tumor type prediction using AI imaging and intraoperative rapid genetic diagnosis. We have further developed intraoperative rapid genetic diagnosis to identify genetic mutations around the tumor, enabling the detection of molecular boundaries. It is now possible to remove as much as possible, considering the molecular boundary, while paying sufficient attention to preservation of brain functions. Gliomas are intractable diseases, but their treatment outcomes have steadily improved over time. We are now in an era of a tailor-made surgery based on a variety of data. Implementing “appropriate surgical procedures” we aim at further improvement of treatment outcomes.

EPCO-07. INTEGRATING SPATIALLY RESOLVED MULTI-OMICS DATA TO UNCOVER DYSFUNCTIONAL METABOLISM DRIVEN NETWORKS THAT ENHANCE INFILTRATION OF DIFFUSE GLIOMAS

Abstract BACKGROUND Diffuse infiltration is an aggressive feature of high-grade gliomas with survival implications. The contribution of crosstalk between non-neoplastic and neoplastic cells to tumor infiltration remains largely understudied due to the lack of profiling techniques that retain spatial information. Spatial multi-omic profiling is a promising approach to comprehensively analyze transcript-omics, prote-omics and metabol-omics on the same tissue section while preserving information about the spatial organization of cells. Integration of these spatial studies allows for inferring the consequences of complex cell-cell communication underlying tumor infiltration. We hypothesize that the glioma edge is enriched with pro-infiltration ligands-receptors driving tumor infiltration. Strategies that disrupt these ligand-receptor networks may suppress glioma infiltration and improve clinical outcomes. METHODS We utilized a glioma tissue micro-array (TMA) to establish the neoplastic and non-neoplastic heterogeneity in the GBM infiltration edge. Each TMA slide consists of pathologist annotated tumor core and edge samples of Glioblastoma (IDH Wildtype, WHO Grade 4; n=10), Diffuse Astrocytoma (IDH Mutant, WHO Grade 3; n=3), Oligodendroglioma (IDH mutant, WHO Grade 2; n=5) and 2 non-brain control samples. We performed spatial multi-omics profiling on adjacent sections of the TMA using 10x Xenium spatial transcriptomics, imaging mass cytometry (IMC) and mass spectrometry imaging (MSI). Integration, visualization, and quantification of the spatial data was done on VisioPharm. RESULTS In GBM, we identified candidate mRNA transcripts and proteins for ligands enriched at the infiltrating edge (compared to tumor core; p&amp;lt;0.0001) that correlated with a poor progression free survival (PFS; r2=0.22). These candidate ligands were also significantly enriched at the edge of oligodendroglioma WHO Grade 2 and astrocytoma WHO Grade 3. CONCLUSIONS Spatial multi-omics profiling on a TMA consisting of Glioma WHO grades 2-4 identified differentially expressed and targetable pro-tumor infiltration ligands associated with lower PFS in GBM. Functional studies to uncover the role of metabolites enriched at the glioma edge for the expression of the identified pro-infiltration ligands are ongoing.

STEM-10. NEURAL PROGENITOR CELL MARKERS IN IDH MUTANT AND IDHWT GLIOMAS

Abstract INTRODUCTION Single-cell RNA sequencing (scRNA-seq) has helped to elucidate the cellular composition of cancer and its microenvironment. Recent scRNA-seq studies have highlighted the heterogeneity of glioblastoma (GBM). Moreover, single-cell GBM analyses have proposed resemblance of GBM cells to radial glia and outer radial glia, supporting the hypothesis that remnants of developmental tissue get reactivated in cancer. A recent study isolated neural progenitor cells (NPCs) from developing fetal human brain (gestational week 17–19) and classified NPCs based on their expression of THY1, CD24 and EGFR. Ventricular radial glia are THY1- CD24-EGFR+ whereas outer radial glia are THY1- CD24-EGFR-. Early neuron precursors are CD24+THY1-EGFR+ and glial progenitor cells (GPCs) are THY1+EGFR+. GPCs give rise to THY1+EGFR+PDGFRA+ pre-oligodendrocyte progenitor cells. The importance of EGFR in NPCs again highlights the resemblance to glioma. METHODS We aimed to apply the classification above to IDH mutant astrocytoma and oligodendroglioma as well as IDHwt glioblastoma samples. We used three publicly available datasets: Wang (paired 74 IDHwt primary and recurrent samples), Tirosh (6 primary oligodendroglioma samples) and Venteicher (10 primary IDH mutant astrocytoma). RESULTS In IDH mutant astrocytoma, 82.63% of cells express THY1+ (mostly EGFR+PDGFRA+) and 10.76% of cells are THY1-CD24-EGFR+. In oligodendroglioma, 75% of cells are THY1+ (mostly EGFR+PDGFRA+) and 12.07% are THY1-CD24-EGFR+. In IDHwt EGFR amplified primary GBM samples, 87.5% of cells are THY1-CD24-EGFR+. This percentage drops to 70.4% in the recurrent setting. THY1-CD24-EGFR- cells increase from 9.7% to 23.1% at recurrence. In IDHwt EGFRwt primary GBM samples, 48.6% of cells are THY1-CD24-EGFR+ and 44.15% are THY1-CD24-EGFR-. In the recurrent setting, 43.26% of cells are THY1-CD24-EGFR+ and 49.58% are THY1-CD24-EGFR-. CONCLUSION IDH mutant gliomas and IDHwt glioblastoma express different progenitor cell markers and may have a different cell of origin. THY1 is highly expressed in IDH mutant gliomas.

NCOG-42. SPEECH-SPECIFIC ERRORS IN LEXICAL RETRIEVAL PREDICT GLIOMA MOLECULAR FEATURES

Abstract Recent work confirms that low and high-grade gliomas, remodel neural circuits which influence speech production. The extent to which speech kinetics and category of speech error during lexical retrieval may predict glioma molecular features remains unknown. Here, we extracted audiovisual speech production from 550 patients totaling over 26,400 individual stimuli to identify correlations with glioma molecular features including IDH, TERT, 1p19q co-deletion, and CDK2AB. Nonparametric statistics were used for analysis. IDH wild-type tumors were more likely to be temporoparietal, while IDH mutant tumors were more likely to be insular (p=0.02). Patients with IDH wild-type glioblastoma exhibited more errors (8.23 vs 3.79, p=0.02), with a higher occurrence of anomia (p=0.004), circumlocution (p=0.034) and general delay (p=0.04) when compared with IDH mutant WHO grade 4 astrocytoma. Binomial logistic regression identified lexical retrieval anomia, circumlocution, and initiation delays as an independent predictor of having an IDH wild-type tumor. Within the IDH mutant group, anomia (p=0.03) and articulation (p=0.014) errors were associated with malignant molecular features (after controlling for prognostic variables such as tumor volume). Binomial logistic regression identified articulation or anomia for picture naming as an independent risk predictor for WHO grade 2 gliomas with greater risk molecular features (based on Ki67 and CDK2AB). Distinct patterns of language errors were observed in patients with IDH wild-type and IDH mutant tumors. Further work is required to elucidate the functional and biological correlates of these findings.

DDDR-26. IDENTIFICATION OF MODULATORS OF IDH INHIBITOR SENSITIVITY INIDH-MUTATED DIFFUSE GLIOMAS

Abstract Driver mutations in IDH1 and IDH2 characterize a substantial proportion of lower-grade diffuse gliomas in adults. Mutated IDH molecules cause the accumulation of D-2-hydroxyglutarate (D-2-HG), which perturbs many cellular functions, including metabolism, epigenetic regulation, and the ability to differentiate. This is notably associated with DNA and histone hyper-methylation. Recently, the newly developed IDH inhibitor, vorasidenib, was shown to delay tumor progression and the need for additional treatment in the groundbreaking INDIGO clinical trial. Nevertheless, the responses to vorasidenib were variable between patients, and so far have been established only for less aggressive disease. In addition, it is unclear to what extent vorasidenib can cause tumor regression. This highlights the need to identify molecules and pathways that control IDH inhibitor sensitivity. Towards this goal, we generated a new mouse model that combines Idh1R132H and Trp53 loss-of-function, targeted to oligodendrocyte progenitors. All the mutant mice develop diffuse gliomas that recapitulate the cardinal features of the corresponding human disease. We established multiple cell lines from these tumors, which retained expression of mutant IDH. The cells robustly produced D-2-HG, which was concentration-dependently suppressed by vorasidenib. Accordingly, vorasidenib could lower DNA methylation, and induce the expression of mature glial cell markers. To identify determinants of vorasidenib sensitivity, we performed genome-wide loss-of-function CRISPR/Cas9 functional genomics screens. In those experiments, targeting genes associated with astrocyte differentiation or Notch signaling enhanced cell fitness in the presence of vorasidenib, consistent with the anticipated effects of the drug on inducing cell differentiation. Conversely, vorasidenib-treated cells were more sensitive to the loss of regulators of cell growth and metabolism, and of some epigenetic regulators. These studies point to strategies that may enhance the efficacy of IDH inhibitors for the treatment of IDH mutated gliomas.

BIOM-61. CSF CTDNA ANALYSIS OF PATIENTS WITH DIFFUSE GLIOMAS REVEALS DIAGNOSTIC MOLECULAR ALTERATIONS

Abstract There is a critical need for better strategies to diagnose and monitor patients with diffuse gliomas. Liquid biopsies are less invasive than tissue biopsies and are amenable to serial collection at multiple timepoints. However, analysis of circulating tumor DNA (ctDNA) in cerebrospinal fluid (CSF) in patients with diffuse gliomas remains underutilized in clinical practice due to technical challenges and a scarcity of studies demonstrating clinical utility. We evaluated ctDNA in 49 CSF samples from patients with various types of diffuse gliomas with a next generation sequencing (NGS) panel interrogating 613 cancer-related genes. Cell-free DNA concentration obtained from CSF (0.4-5mL) ranged from 0.009 to 60ng/µL. Input DNA concentration ranged from 0.12-30ng. Mutations were detected in 29/49 (59.2%) samples including 22/49 (44.9%) with single nucleotide changes, 14/49 (28.6%) with copy number changes, and 1 fusion (2.0%). The majority of samples without mutations detected (n=20) had suboptimal DNA input (&amp;lt;30ng): 17/20 (85%). We identified diagnostic alterations in CSF including mutations in IDH1 (3/5 IDH-mutant gliomas), TERTp and EGFR amplification (7/34 glioblastomas), H3-3A (4/6 pediatric high-grade gliomas). Some of these mutations, in combination with other clinical parameters, allowed us to identify specific CNS tumor types based on the 2021 WHO classification of CNS tumors, resulting in the reclassification of 2 patients. Matched tumor tissue sequencing results were available for 23/49 (46.9%) patients and the results showed good concordance with CSF ctDNA analysis. In summary, our results suggest that the NGS analysis of CSF-ctDNA can provide clinically relevant information in patients with diffuse gliomas.

TMIC-64. EXPLORING ULTRASTRUCTURAL PATHOLOGY IN GLIOMAS: INSIGHTS FROM RECENT STUDIES

Abstract Glioma tumors arise from the glial cells making up to 40% of the brain tumors, and contributing up to 85% of the malignant tumors of the brain. Gliomas are a heterogeneous group of tumors classified based on various factors such as genetics, molecular profiles, etc. Glioblastoma, an aggressive form of gliomas, has incredibly low survival of only 15 months suggesting that thorough research, improved diagnostics, and therapeutics development is needed to improve the outcomes for patients with gliomas. These advancements require a critical analysis of the microenvironment of gliomas to understand the pathophysiology at play. Ultrastructural analysis (UA) using high-resolution electron microscopy offers crucial insights into the cellular and subcellular characteristics of gliomas, revealing organelle abnormalities and confirming molecular alterations. In this review, we focus on the recent developments exploring the ultrastructural pathology of gliomas. UA shows a detailed microenvironment of gliomas to reveal the abnormal presence of lipids in the intra- and extracellular environment of gliomas accompanied by the disrupted structure of the cellular membranes and organelles. The disruptions were noted in the blood vessels of the tumors displaying intriguing details regarding the formation of neovasculature and the absence of typical contents of vessel walls like endothelial cells. A comparative survey of the mitochondrial ultrastructure of gliomas with or without IDH1 mutations also reveals the role of UA in deciphering the impact of different mutations on the microenvironment level. Here, we also discuss the major implications of these findings regarding the research direction, diagnostic modalities, and therapeutic options.

BIOM-28. WHOLE EXOME TUMOR MOLECULAR PROFILING FROM CEREBROSPINAL FLUID (CSF): PRELIMINARY RESULTS OF A PILOT STUDY

Abstract BACKGROUND Tissue sampling for molecular profiling has become an integral part of the diagnosis, prognosis, and management of CNS malignancies. However, many tumors are surgically inaccessible, and even biopsy of accessible lesions conveys some risk, and the possibility of sampling error. We evaluated the accuracy and potential utility of CSF liquid biopsy for identifying mutations in patients with intracranial tumors. METHODS CSF samples were collected from ventricular reservoirs and stored at -80 degrees Celsius until analyzed. Cell-free nucleic acids were extracted, concentrated, and quantified. Samples over 110ng quantification were normalized to 110ng and input into library prep. Library prep was done using v3.5 of Caris Assure and whole exome sequencing in an S2 FC on a Novaseq 6000. Bioinformatic analysis was performed. RESULTS CSF samples were obtained from 20 patients (10 gliomas, 5 CNS lymphomas, 5 metastases), 19 of whom also had tumor specimens available. Two hundred eighty-one mutations were identified: 17 (6.6%) in tumor only, 184 (72.4%) in CSF only, and 80 (31.5%) in both. Key alterations found in CSF include: IDH, TERT, ATRX in gliomas, and MYD88, PIM1, BCL2, TERT in lymphomas. Glioma CSF with IDH1 mutations did not have PTEN mutations (with one exception, in which the CSF was collected 3 years after the tissue). Targetable mutations in metastases included PIK3CA, NF1, and BRCA. CONCLUSION These preliminary results suggest that CSF liquid biopsy may be useful for identifying mutations in primary and metastatic brain tumors. Serial sampling is feasible, and may disclose changes in diagnostic and/or driver mutations over time, with important therapeutic and diagnostic implications. Many mutations were found in CSF alone. CSF may capture the entire molecular landscape of the tumor, overcoming the sampling error inherent in tissue biopsies. Prospective studies are underway to further elucidate the clinical applications of this technique.

NCMP-10. EFFECT OF EXTENT OF RESECTION ON GLIOMA SEIZURE OUTCOMES BASED ON MOLECULAR GROUPS

Abstract INTRODUCTION Increased extent of resection (EOR) is a known predictor of seizure freedom in glioma patients. However, it is unknown how tumor genomic alterations affect EOR-induced seizure control. OBJECTIVE To evaluate the genotype-specific impact of EOR on post-operative seizure control METHODS Records of 553 glioma patients who underwent tumor resection from 2012-2023 were reviewed. All patient tumors were analyzed with next generation sequencing and FISH analysis. The unsupervised machine learning algorithm non-negative matrix factorization (NMF) was used to cluster the genomic data. Clinical variables including extent of resection of contrast enhancing tumor and non-enhancing tumor, temozolomide therapy, and radiation therapy were analyzed using Cox Proportional Hazards models. RESULTS NMF clustering of tumor sequencing data revealed four molecular groups: Group 1 (n=56): CDKN2a loss, EGFR copy number gain or mutation, TERT promoter (TERTp) mutation, and MGMT methylated; Group 2 (n=27): IDH mutation, TP53 mutation, and MGMT methylated; Group 3 (n=60): TP53 mutation, TERTp mutation and MGMT methylated; Group 4 (n=244): MGMT unmethylated. Thresholds in the post-operative residual non-enhancing tumor volume (NETV) were identified which marked the most difference in seizure control. For patients in Group 1, the NETV threshold that led to improved epilepsy outcomes was &amp;lt;94.7 cc (p=0.047), whereas the threshold for Group 4 was &amp;lt;89.1 cc (p=0.016). When analysis was conducted for Group 2, the threshold of 10.2 cc failed to reach significance (p=0.1). Interestingly, the threshold analysis for Group 3 found that having a NETV of &amp;gt; 10.1 cc showed improved seizure outcomes (p=0.016). A multivariable cox proportional hazard analysis found that twelve-month seizure freedom was predictive of better OS in group 1 (HR 0.02, p=0.05) and group 4 (HR 0.21, p=1.63e-9). CONCLUSION Our study reveals clinically distinct molecular groups of glioma that display different seizure responses. This data suggests a tumor-specific approach to aggressiveness of extent of resection in order to achieve optimal seizure control.

Identification of a coagulation-related gene signature for predicting prognosis in recurrent glioma.

Recurrent gliomas rapidly progress and have high mortality and poor prognosis in the central nervous system. Therefore, further investigation of prognostic and therapeutic markers is needed. The mRNA expression, clinical data, and coagulation-related genes (CRGs) associated with recurrent glioma were obtained and calculated from the Chinese Glioma Genome Atlas and Kyoto Encyclopedia of Genes and Genomes databases. The significant CRGs were calculated by Weighted gene co-expression network analysis and PPI network. A prediction model was constructed using the least absolute shrinkage and selection operator regression analysis. Recurrent gliomas were stratified into high and low-risk groups based on the median risk score (RS). The Kaplan-Meier curve was used to analyze the difference in overall survival (OS) between these groups, while the receiver operating characteristic (ROC) curve was used to evaluate the accuracy of the gene model at 1-, 3-, and 5-years. Clinical factors, including age, gender, MGMT methylation status, radiotherapy, chemotherapy, and RS, were included in the univariate and multivariate regression analysis. A prognostic nomogram and calibration curve were established based on these factors. Overall, seven CRGs associated with the prognosis were identified, including BTK, ITGB1, GNAI3, CFH, LYN, CFI, and F3. OS and survival rates were lower in the high-risk group compared with the low-risk group. The ROC curve demonstrated the area under the curve values >0.65 at 1-, 3-, and 5-years, confirming the reliability of the prognostic model. The univariate regression analysis indicated that tumor grade (grades 2, 3, and 4), histopathology (GBM or not), chemotherapy, IDH mutation, and 1p19q co-deletion status were independent prognostic indicators. Univariate and multivariate regression analyses indicated that RS was an independent prognostic factor for patients with recurrent glioma. Immune analysis revealed low infiltration of resting dendritic cells and high expression of programmed death receptor 1 in the high-risk group. This study comprehensively investigated the correlation between CRGs and recurrent glioma prognosis, offering crucial insights for further research into glioma recurrence mechanisms and treatment strategies.

PATH-18. CURRENT STATUS OF CANCER GENOMIC PROFILING (CGP) TESTS IN BRAIN TUMOR TREATMENT - COMPLEMENTING BRAIN TUMOR PATHOLOGICAL DIAGNOSIS WITH CGP-

Abstract INTRODUCTION Cancer genomic profiling (CGP) tests are currently used in the search for therapeutic targets and have become an auxiliary tool in diagnosis according to the new WHO classification (WHO 2021), which requires the integration of pathomorphological and molecular diagnostics. Here, we report on brain tumor cases at our institution that underwent CGP testing. METHODS From May 2020 to the present, 27 brain tumor cases that underwent CGP testing at our institution were included in this study. There were 14 males and 13 females, ranging from 18 to 70 years (average 48.4 years). The tests conducted included Foundation One CDx, GeneMineTop, and NCC OncoPanel. RESULTS The cases that underwent CGP testing included 13 cases of glioblastoma IDH-wildtype, 3 cases of astrocytoma, IDH-mutant, grade 4, 4 cases of astrocytoma IDH-mutant, grade 3, 3 cases of oligodendroglioma, 1p/19q codeleted, grade 3, 1 case of astrocytoma, IDH-mutant, grade 2, 1 case of ependymoma, 1 case of pilocytic astrocytoma and 1 case of PitNEC. CGP testing enabled molecular diagnostics such as IDH mutation and TERTp mutation. Based on the results, therapeutic suggestions were possible for 5 out of 25 cases (20%) (BRAF V600E mutation 1 case, IDH1 R132H mutation 1 case, TMB high 3 cases). Checkpoint inhibitors were used in a case with high TMB. Genetic risk assessment by a genetic counselor was conducted for all cases, and one high TMB case was diagnosed as hereditary cancer. A germline pathogenic variant in MSH6 was detected, leading to a diagnosis of Lynch syndrome. CONCLUSION Molecular diagnostics through CGP testing served as an aid in diagnosis according to WHO2021. Cases where drug suggestions were feasible underwent treatment with targeted molecular therapies and checkpoint inhibitor. We experienced cases where hereditary cancer syndromes such as Lynch syndrome were diagnosed through the detection of germline pathogenic variants.