Differential tractography and whole brain connectometry in primary motor area gliomas resection: A feasibility study.

OBJECTIVE: Establish the evolution of the connectome before and after resection of motor area glioma using a comparison of connectome maps and high-definition differential tractography (DifT). METHODS: DifT was done using normalized quantitative anisotropy (NQA) with DSI Studio. The quantitative analysis involved obtaining mean NQA and fractional anisotropy (FA) values for the disrupted pathways tracing the corticospinal tract (CST), and white fiber network changes over time. RESULTS: We described the baseline tractography, DifT, and white matter network changes from two patients who underwent resection of an oligodendroglioma (Case 1) and an IDH mutant astrocytoma, grade 4 (Case 2). CASE 1: There was a slight decrease in the diffusion signal of the compromised CST in the immediate postop. The NQA and FA values increased at the 1-year follow-up (0.18 vs. 0.32 and 0.35 vs. 0.44, respectively). CASE 2: There was an important decrease in the immediate postop, followed by an increase in the follow-up. In the 1-year follow-up, the patient presented with radiation necrosis and tumor recurrence, increasing NQA from 0.18 in the preop to 0.29. Fiber network analysis: whole-brain connectome comparison demonstrated no significant changes in the immediate postop. However, in the 1-year follow up there was a notorious reorganization of the fibers in both cases, showing the decreased density of connections. CONCLUSIONS: Connectome studies and DifT constitute new potential tools to predict early reorganization changes in a patient's networks, showing the brain plasticity capacity, and helping to establish timelines for the progression of the tumor and treatment-induced changes.

Mutant IDH inhibitors induce lineage differentiation in IDH-mutant oligodendroglioma.

A subset of patients with IDH-mutant glioma respond to inhibitors of mutant IDH (IDHi), yet the molecular underpinnings of such responses are not understood. Here, we profiled by single-cell or single-nucleus RNA-sequencing three IDH-mutant oligodendrogliomas from patients who derived clinical benefit from IDHi. Importantly, the tissues were sampled on-drug, four weeks from treatment initiation. We further integrate our findings with analysis of single-cell and bulk transcriptomes from independent cohorts and experimental models. We find that IDHi treatment induces a robust differentiation toward the astrocytic lineage, accompanied by a depletion of stem-like cells and a reduction of cell proliferation. Furthermore, mutations in NOTCH1 are associated with decreased astrocytic differentiation and may limit the response to IDHi. Our study highlights the differentiating potential of IDHi on the cellular hierarchies that drive oligodendrogliomas and suggests a genetic modifier that may improve patient stratification.

Association of Clinical, Tumor, and Treatment Characteristics With Seizure Control in Patients With IDH1/2-Mutant Lower-Grade Glioma.

BACKGROUND AND OBJECTIVES: Patients with IDH1/2-mutant lower-grade glioma have a high frequency of seizures. We aimed to investigate the correlations between seizures and tumor/patient characteristics and the impact of surgery and adjuvant treatments (AT) on seizure control along the disease trajectory. METHODS: We retrospectively included patients with IDH1/2-mutant lower-grade glioma who underwent surgery at the neurosurgery divisions of the University of Turin and Milan and were treated at the Division of Neuro-Oncology of Turin. Inclusion criteria were a diagnosis according to the 2021 WHO Classification and presentation with seizures; exclusion criteria were presence of CDKN2A/B homozygous deletion, intense/ring contrast enhancement on MRI at presentation, and small tissue biopsy. We evaluated seizure freedom for 2 months after surgery, 6 months from starting observation or AT, at recurrence, and for 6 months after treatments of recurrence. RESULTS: We included 150 patients. There were 77 (51%) and 31 (21%) patients with IDH-mutant/1p19q-codeleted grade 2 and 3 oligodendroglioma and 30 (20%) and 12 (8%) with IDH-mutant grade 2 and 3 astrocytoma, respectively. Total resection was accomplished in 68 (45%). Seventy-five patients (50%) received AT while the remaining 75 were observed with MRI. After 6 months after AT, 28 of 29 patients (96.5%) displayed seizure reduction, 5 of 28 (18%) being seizure-free. 66 of 124 patients (53%) had seizures at recurrence. After 6 months after second-line treatments, 60 of 66 patients (91%) had seizure reduction, 11 (17%) being seizure-free. In multivariable analyses, grade 3 histology positively correlated with seizure freedom at 2 months after surgery (OR 3.5, 1.4-8.9, p = 0.008), 6 months after AT (OR 9.0, 1.5-54.9, p = 0.017), and 6 months after treatment of recurrence (OR 4.9, 1.5-16.5, p = 0.009). Adjuvant radiotherapy reduced seizures at recurrence in a univariate analysis (OR 0.14, 0.03-0.7, p = 0.020). Patients with seizure freedom after surgery and AT displayed longer progression-free survival (PFS) (65, 24.5-105, vs 48 months, 32-63.5, p = 0.037). DISCUSSION: This study analyzed seizure control in patients with IDH1/2-mutant lower-grade glioma across multiple time points. Grade 3 correlated with better seizure control throughout the entire disease trajectory, and seizure freedom after surgery and AT correlated with a longer PFS regardless of tumor grade. These results could serve as an external control arm in clinical trials evaluating the efficacy on seizures of antitumor agents in patients with IDH-mutant lower-grade glioma.

Oligodendroglioma, IDH-mutant and 1p/19q-codeleted-prognostic factors, standard of care and chemotherapy, and future perspectives with neoadjuvant strategy.

Oligodendroglioma, IDH-mutant and 1p/19q-codeleted is known for their relative chemosensitivity and indolent clinical course among diffuse gliomas of adult type. Based on the data from phase 3 clinical trials, the standard of post-surgical care for those tumors is considered to be initial chemoradiotherapy regardless of histopathological grade, particularly with PCV. However, partly due to its renewed definition in late years, prognostic factors in patients with those tumors are not well established. Moreover, the survival rate declines over 15 years, with only a 37% OS rate at 20 years for grade 3 tumors, even with the current standard of care. Given that most of this disease occurs in young or middle-aged adults, further improvements in treatment and management are necessary. Here, we discuss prognostic factors, standard of care and chemotherapy, and future perspectives with neoadjuvant strategy in those tumors.

The development of a custom RNA-sequencing panel for the identification of predictive and diagnostic biomarkers in glioma.

PURPOSE: Various molecular profiles are needed to classify malignant brain tumors, including gliomas, based on the latest classification criteria of the World Health Organization, and their poor prognosis necessitates new therapeutic targets. The Todai OncoPanel 2 RNA Panel (TOP2-RNA) is a custom-target RNA-sequencing (RNA-seq) using the junction capture method to maximize the sensitivity of detecting 455 fusion gene transcripts and analyze the expression profiles of 1,390 genes. This study aimed to classify gliomas and identify their molecular targets using TOP2-RNA. METHODS: A total of 124 frozen samples of malignant gliomas were subjected to TOP2-RNA for classification based on their molecular profiles and the identification of molecular targets. RESULTS: Among 55 glioblastoma cases, gene fusions were detected in 11 cases (20%), including novel MET fusions. Seven tyrosine kinase genes were found to be overexpressed in 15 cases (27.3%). In contrast to isocitrate dehydrogenase (IDH) wild-type glioblastoma, IDH-mutant tumors, including astrocytomas and oligodendrogliomas, barely harbor fusion genes or gene overexpression. Of the 34 overexpressed tyrosine kinase genes, MDM2 and CDK4 in glioblastoma, 22 copy number amplifications (64.7%) were observed. When comparing astrocytomas and oligodendrogliomas in gene set enrichment analysis, the gene sets related to 1p36 and 19q were highly enriched in astrocytomas, suggesting that regional genomic DNA copy number alterations can be evaluated by gene expression analysis. CONCLUSIONS: TOP2-RNA is a highly sensitive assay for detecting fusion genes, exon skipping, and aberrant gene expression. Alterations in targetable driver genes were identified in more than 50% of glioblastoma. Molecular profiling by TOP2-RNA provides ample predictive, prognostic, and diagnostic biomarkers that may not be identified by conventional assays and, therefore, is expected to increase treatment options for individual patients with glioma.

BCAS1 defines a heterogeneous cell population in diffuse gliomas.

Oligodendrocyte precursor markers have become of great interest to identify new diagnostic and therapeutic targets for diffuse gliomas, since state-of-the-art studies point towards immature oligodendrocytes as a possible source of gliomagenesis. Brain enriched myelin associated protein 1 (BCAS1) is a novel marker of immature oligodendrocytes and was proposed to contribute to tumorigenesis in non-central nervous system tumors. However, BCAS1 role in diffuse glioma is still underexplored. This study analyzes the expression of BCAS1 in different tumor samples from patients with diffuse gliomas (17 oligodendrogliomas; 8 astrocytomas; 60 glioblastomas) and uncovers the molecular and ultrastructural features of BCAS1+ cells by immunostaining and electron microscopy. Our results show that BCAS1+ cells exhibit stellate or spherical morphology with similar ultrastructural features. Stellate and spherical cells were detected as isolated cells in all studied gliomas. Nevertheless, only stellate cells were found to be proliferative and formed tightly packed nodules with a highly proliferative rate in oligodendrogliomas. Our findings provide a comprehensive characterization of the BCAS1+ cell population within diffuse gliomas. The observed proliferative capacity and distribution of BCAS1+ stellate cells, particularly in oligodendrogliomas, highlight BCAS1 as an interesting marker, warranting further investigation into its role in tumor malignancy.

Reliable detection of genetic alterations in cyst fluid DNA for the diagnosis of brain tumors.

PURPOSE: Liquid biopsy of cyst fluid in brain tumors has not been extensively studied to date. The present study was performed to see whether diagnostic genetic alterations found in brain tumor tissue DNA could also be detected in cell-free DNA (cfDNA) of cyst fluid in cystic brain tumors. METHODS: Cyst fluid was obtained from 22 patients undergoing surgery for a cystic brain tumor with confirmed genetic alterations in tumor DNA. Pathological diagnoses based on WHO 2021 classification and diagnostic alterations in the tumor DNA, such as IDH1 R132H and TERT promoter mutation for oligodendrogliomas, were detected by Sanger sequencing. The same alterations were analyzed by both droplet digital PCR (ddPCR) and Sanger sequencing in cyst fluid cfDNA. Additionally, multiplex ligation-dependent probe amplification (MLPA) assays were performed to assess 1p/19q status, presence of CDKN2A loss, PTEN loss and EGFR amplification, to assess whether differentiating between astrocytomas and oligodendrogliomas and grading is possible from cyst fluid cfDNA. RESULTS: Twenty-five genetic alterations were found in 22 tumor samples. All (100%) alterations were detected in cyst fluid cfDNA by ddPCR. Twenty of the 25 (80%) alterations were also detected by Sanger sequencing of cyst fluid cfDNA. Variant allele frequency (VAF) in cyst fluid cfDNA was comparable to that of tumor DNA (R = 0.62, Pearson's correlation). MLPA was feasible in 11 out of 17 (65%) diffuse gliomas, with close correlation of results between tumor DNA and cyst fluid cfDNA. CONCLUSION: Cell-free DNA obtained from cyst fluid in cystic brain tumors is a reliable alternative to tumor DNA when diagnosing brain tumors.

Rise of oligodendroglioma hypermutator phenotype from a subclone harboring TP53 mutation after TMZ treatment.

Oligodendrogliomas characterized and defined by 1p/19q co-deletion are slowly growing tumors showing better prognosis than astrocytomas. TP53 mutation is rare in oligodendrogliomas while the vast majority of astrocytomas harbor the mutation, making TP53 mutation mutually exclusive with 1p/19q codeletion in lower grade gliomas virtually. We report a case of 51-year-old woman with a left fronto-temporal oligodendroglioma that contained a small portion with a TP53 mutation, R248Q, at the initial surgery. On a first, slow-growing recurrence 29 months after radiation and nitrosourea-based chemotherapy, the patient underwent TMZ chemotherapy. The recurrent tumor responded well to TMZ but developed a rapid progression after 6 cycles as a malignant hypermutator tumor with a MSH6 mutation. Most of the recurrent tumor lacked typical oligodendroglioma morphology that was observed in the primary tumor, while it retained the IDH1 mutation and 1p/19q co-deletion. The identical TP53 mutation observed in the small portion of the primary tumor was universal in the recurrence. This case embodied the theoretically understandable clonal expansion of the TP53 mutation with additional mismatch repair gene dysfunction leading to hypermutator phenotype. It thus indicated that TP53 mutation in oligodendroglioma, although not common, may play a critical role in the development of hypermutator after TMZ treatment.

Exploiting nanopore sequencing for characterization and grading of IDH-mutant gliomas.

The 2021 WHO Classification of Central Nervous System Tumors recommended evaluation of cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) deletion in addition to codeletion of 1p/19q to characterize IDH-mutant gliomas. Here, we demonstrated the use of a nanopore-based copy-number variation sequencing (nCNV-seq) approach to simultaneously identify deletions of CDKN2A/B and 1p/19q. The nCNV-seq approach was initially evaluated on three distinct glioma cell lines and then applied to 19 IDH-mutant gliomas (8 astrocytomas and 11 oligodendrogliomas) from patients. The whole-arm 1p/19q codeletion was detected in all oligodendrogliomas with high concordance among nCNV-seq, FISH, DNA methylation profiling, and whole-genome sequencing. For the CDKN2A/B deletion, nCNV-seq detected the loss in both astrocytoma and oligodendroglioma, with strong correlation with the CNV profiles derived from whole-genome sequencing (Pearson correlation (r) = 0.95, P < 2.2 × 10-16 to r = 0.99, P < 2.2 × 10-16 ) and methylome profiling. Furthermore, nCNV-seq can differentiate between homozygous and hemizygous deletions of CDKN2A/B. Taken together, nCNV-seq holds promise as a new, alternative approach for a rapid and simultaneous detection of the molecular signatures of IDH-mutant gliomas without capital expenditure for a sequencer.

Profiling of circulating glial cells for accurate blood-based diagnosis of glial malignancies.

Here, we describe a blood test for the detection of glial malignancies (GLI-M) based on the identification of circulating glial cells (CGCs). The test is highly specific for GLI-M and can detect multiple grades (II-IV) and subtypes including gliomas, astrocytomas, oligodendrogliomas, oligoastrocytomas and glioblastomas, irrespective of gender and age. Analytical validation of the test was performed as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Real-world performance characteristics of the test were evaluated in four clinical (observational) studies. The test has high analytical sensitivity (95%), specificity (100%) and precision (coefficient of variation [CV] = 13.7% for repeatability and CV = 23.5% for within laboratory precision, both at the detection threshold) and is not prone to interference from common drugs and serum factors. The ability of the test to detect and differentiate GLI-M from non-malignant brain tumours (NBT), brain metastases from primary epithelial malignancies (EPI-M) and healthy individual donors (HD) was evaluated in four clinical cohorts. Across these clinical studies, the test showed 99.35% sensitivity (95% confidence interval [CI]: 96.44%-99.98%) and 100% specificity (95% CI: 99.37%-100%). The performance characteristics of this test support its clinical utility for diagnostic triaging of individuals presenting with intracranial space-occupying lesions (ICSOL).

Immunohistochemical analyses of neural stem cell lineage markers in normal feline brains and glial tumors.

Neural stem cell (NSC) lineage cells have not been fully identified in feline brains, and the NSC-like nature of feline glial tumors has not been determined. In this study, 6 normal cat brains (3 newborn and 3 older cats) and 13 feline glial tumors were analyzed using immunohistochemical NSC lineage markers. The feline glial tumors were subjected to immunohistochemical scoring followed by hierarchical cluster analysis. In newborn brains, glial acidic fibrillary protein (GFAP)/nestin/sex-determining region Y-box transcription factor 2 (SOX2)-immunopositive NSCs, SOX2-immunopositive intermediate progenitor cells, oligodendrocyte transcription factor 2 (OLIG2)/platelet-derived growth factor receptor-α (PDGFR-α)-immunopositive oligodendrocyte precursor cells (OPCs), OLIG2/GFAP-immunopositive immature astrocytes, and neuronal nuclear (NeuN)/ß-3 tubulin-immunopositive mature neuronal cells were observed. The apical membrane of NSCs was also immunopositive for Na+/H+ exchanger regulatory factor 1 (NHERF1). In mature brains, the NSC lineage cells were similar to those of the newborn brains. A total of 13 glial tumors consisted of 2 oligodendrogliomas, 4 astrocytomas, 3 subependymomas, and 4 ependymomas. Astrocytomas, subependymomas, and ependymomas were immunopositive for GFAP, nestin, and SOX2. Subependymomas and ependymomas showed dot-like or apical membrane immunolabeling for NHERF1, respectively. Astrocytomas were immunopositive for OLIG2. Oligodendrogliomas and subependymomas were immunopositive for OLIG2 and PDGFR-α. Feline glial tumors also showed variable immunolabeling for ß-3 tubulin, NeuN, and synaptophysin. Based on these results, feline astrocytomas, subependymomas, and ependymomas appear to have an NSC-like immunophenotype. In addition, astrocytomas, subependymomas, and ependymomas have the characteristics of glial, oligodendrocyte precursor, and ependymal cells, respectively. Feline oligodendrogliomas likely have an OPC-like immunophenotype. In addition, feline glial tumors may have multipotential stemness for differentiation into neuronal cells. These preliminary results should be validated by gene expression analyses in future studies with larger case numbers.

Long-Term Tumor Control Following Targeted Alpha Therapy (TAT) of Low-Grade Gliomas (LGGs): A New Treatment Paradigm?

The median survival time has been reported to vary between 5 and 8 years in low-grade (WHO grade 2) astrocytoma, and between 10 and 15 years for grade 2 oligodendroglioma. Targeted alpha therapy (TAT), using the modified peptide vector [213Bi]Bi/[225Ac]Ac-DOTA-substance P, has been developed to treat glioblastoma (GBM), a prevalent malignant brain tumor. In order to assess the risk of late neurotoxicity, assuming that reduced tumor cell proliferation and invasion should directly translate into good responses in low-grade gliomas (LGGs), a limited number of patients with diffuse invasive astrocytoma (n = 8) and oligodendroglioma (n = 3) were offered TAT. In two oligodendroglioma patients, TAT was applied as a second-line treatment for tumor progression, 10 years after targeted beta therapy using [90Y]Y-DOTA-substance P. The radiopharmaceutical was locally injected directly into the tumor via a stereotactic insertion of a capsule-catheter system. The activity used for radiolabeling was 2-2.5 GBq of Bismuth-213 and 17 to 35 MBq of Actinium-225, mostly applied in a single fraction. The recurrence-free survival times were in the range of 2 to 16 years (median 11 years) in low-grade astrocytoma (n = 8), in which TAT was administered following a biopsy or tumor debulking. Regarding oligodendroglioma, the recurrence-free survival time was 24 years in the first case treated, and 4 and 5 years in the two second-line cases. In conclusion, TAT leads to long-term tumor control in the majority of patients with LGG, and recurrence has so far not manifested in patients with low-grade (grade 2) astrocytomas who received TAT as a first-line therapy. We conclude that targeted alpha therapy has the potential to become a new treatment paradigm in LGG.

Tumor heterogeneity and tumor-microglia interactions in primary and recurrent IDH1-mutant gliomas.

The isocitrate dehydrogenase (IDH) gene is recurrently mutated in adult diffuse gliomas. IDH-mutant gliomas are categorized into oligodendrogliomas and astrocytomas, each with unique pathological features. Here, we use single-nucleus RNA and ATAC sequencing to compare the molecular heterogeneity of these glioma subtypes. In addition to astrocyte-like, oligodendrocyte progenitor-like, and cycling tumor subpopulations, a tumor population enriched for ribosomal genes and translation elongation factors is primarily present in oligodendrogliomas. Longitudinal analysis of astrocytomas indicates that the proportion of tumor subpopulations remains stable in recurrent tumors. Analysis of tumor-associated microglia/macrophages (TAMs) reveals significant differences between oligodendrogliomas, with astrocytomas harboring inflammatory TAMs expressing phosphorylated STAT1, as confirmed by immunohistochemistry. Furthermore, inferred receptor-ligand interactions between tumor subpopulations and TAMs may contribute to TAM state diversity. Overall, our study sheds light on distinct tumor populations, TAM heterogeneity, TAM-tumor interactions in IDH-mutant glioma subtypes, and the relative stability of tumor subpopulations in recurrent astrocytomas.

Glioma with cribriform plate involvement in 6 dogs.

Distinct patterns of local infiltration are a common feature of canine oligodendroglioma and astrocytoma, and typically involve the surrounding neuroparenchyma, ventricles, or leptomeninges. Infiltration of adjacent extraneural sites is rare and has not been well documented in veterinary medicine. Here we describe 6 canine gliomas with cribriform plate involvement (compression or infiltration) and caudal nasal invasion confirmed by neuroimaging, autopsy, and/or histology. All affected dogs were adults (9-12-y-old), and 3 were brachycephalic. Clinical signs were associated with the brain tumor, with no respiratory signs reported. Magnetic resonance imaging in 2 patients revealed a rostral intraparenchymal telencephalic mass with extension into the cribriform plate. All dogs were euthanized. Gross changes consisted of poorly demarcated, white or pale-yellow, soft, and, in oligodendrogliomas, gelatinous, intraparenchymal masses that expanded the rostral portions of the telencephalon and adhered firmly to the ethmoid bone and cribriform plate. Gliomas were classified as high-grade oligodendrogliomas (4 cases) and high-grade astrocytomas (2 cases) based on histology and immunohistochemistry for OLIG2 and GFAP. In all cases, there was evidence of cribriform plate invasion and, in one case, additional invasion of the caudal nasal cavity.

Evaluation of chromosome 1p/19q deletion by Fluorescence in Situ Hybridization (FISH) as prognostic factors in malignant glioma patients on treatment with alkylating chemotherapy.

BACKGROUND: Either deletion or co-deletion of chromosomal arms 1p or 19q is a characteristic and early genetic event in oligodendroglial tumors that is associated with a better prognosis and enhanced response to therapy. Information of 1p/19q status is now regarded as the standard of care when managing oligodendroglial tumors for therapeutic options in anticipation of the increased survival and progression-free survival times associated with it. Keeping this in view, we first time attempted to establish the FISH based detection of 1p/19q deletion in glioma tissue samples to evaluate its role and involvement in the disease. METHOD: Overall 39 glioma cases of different histologies were evaluated by fluorescence in situ hybridization (FISH) technique using specific FISH probes with Olympus BX43 fluorescent microscope to detect chromosomes 1p and 19q or co-deletions therein. RESULTS: Of the 39 glioma samples, overall 27 (69.2%) were found to have deletion either in 1p, 19q or both. Deletions were observed in 23.0%, 7.6% and 38.4% in 1p, 19q and 1p/19q co-deletions respectively. Overall oligidendrioglioma presented with 53.8% (21 of 39) deletions, astrocytoma group showed 12.8% and GBM accounted for 2.5% deletions. Overall survival and disease free survival was seen significantly better in oligidendrioglioma and astrocytoma with deleted tumors as compared to non-deleted ones (p<0.05). CONCLUSION: Allelic losses on 1p and 19q, either discretely or shared, were more frequent in classic oligodendrogliomas than in either astrocytoma or Glioblastoma with better survival and response to therapy.

Anaplastic oligodendroglioma with nasal invasion and systemic metastasis in a dog.

An 11-year-old spayed female French bulldog was referred on suspicion of nasal tumor. Anaplastic oligodendroglioma in the olfactory bulb that was suspected to have invaded the nasal cavity was diagnosed from imaging and histopathology. Metastasis to cervical lymph nodes was suspected, with no other metastases identified. The brain-to-nasal lesion and lymph nodes were treated with hypo-fractionated radiation therapy. Nasal congestion soon resolved. About 3 months later, follow-up computed tomography revealed multiple hepatic and splenic masses, which were cytologically suspected as metastatic oligodendroglioma. Nimustine, followed by toceranib phosphate, seemed to have no effect, and the dog died on day 167. Postmortem examination revealed the primary tumor disappearance and systemic metastases. Canine oligodendroglioma can grow outside the cranial vault, and systemically metastasize.

Diagnostic algorithm for pathological evaluation of gliomas in a resource-constrained setting.

Introduction: Gliomas are the most common primary intracranial tumors. The current World Health Organization (WHO) classification of central nervous system tumors recommends integrated histo-molecular diagnosis of gliomas. However, molecular testing is not available in even most of the advanced centers of our country, and histopathology aided with immunohistochemistry (IHC) is still widely used for diagnosis. Immunohistochemical markers such as iso-citrate dehydrogenase1 (IDH1) and Alpha Thalassemia/Mental Retardation Syndrome X-linked (ATRX) can be reliably used for the correct diagnosis, prognosis, and treatment of gliomas. Aim: We aimed to develop a diagnostic algorithm by integrating morphology, IDH1, and ATRX status of gliomas seen in our institute for 1 year. Settings and Design: Analytical cross-sectional study. Materials and Methods: This study included 60 histopathologically confirmed cases of astrocytic (n = 51) and oligodendroglial tumors (n = 9). Clinical, radiological, and histopathological features were noted and tumor grades assigned according to the WHO recommendations. IDH1 and ATRX mutation status was evaluated using IHC. The tumors were divided into three molecular groups on the basis of their IDH1 and ATRX mutation status: (1) Group 1: IDH1 negative and ATRX positive, (2) Group 2: IDH1 positive and ATRX positive, (3) Group 3: IDH1 positive and ATRX negative. Results: The mean age of presentation was 45.0 ± 15.8 years with a male-to-female ratio of 2:1. Seizures, headache, and hemiparesis were the most common modes of presentation. The tumor subtypes studied were glioblastoma (n = 32), anaplastic astrocytoma (n = 7), diffuse astrocytoma (n = 6), oligodendroglioma (n = 6), pilocytic astrocytoma (n = 6), and anaplastic oligodendroglioma (n = 3). IDH1 mutation was present in 26 cases including anaplastic astrocytoma (n = 7), diffuse astrocytoma (n = 6), oligodendroglioma (n = 5), secondary glioblastoma (n = 5), and anaplastic oligodendroglioma (n = 3). ATRX mutation, i. e., loss of ATRX was observed in 17 cases including diffuse astrocytoma (n = 5), anaplastic astocytoma (n = 5), anaplastic oligodendroglioma (n = 3), oligodendroglioma (n = 3), and secondary glioblastoma (n = 1). All six cases of pilocytic astrocytoma were negative for IDH1 and ATRX mutation. There were 34 patients in Group 1 (IDH1- and ATRX +), nine cases in Group 2 (IDH1 + and ATRX +), and 17 patients in Group 3 (IDH1 + and ATRX-). Conclusion: Diagnosis of gliomas should be based on a detailed clinicoradiological and histopathological assessment, followed by genotypic characterization. Evaluation for IDH1and ATRX status has both diagnostic and prognostic value as it helps in differentiating gliomas from reactive gliosis, primary glioblastoma from secondary glioblastoma, and pilocytic astrocytoma (WHO grade I) from diffuse astrocytoma (WHO grade II). Tumors with IDH1 mutations have a better outcome than those with wild-type IDH. IHC can serve as a useful surrogate to conventional molecular tests in resource-constrained settings. By devising an algorithm based on morphological and IHC features, we were able to stratify gliomas into three prognostic subgroups.

Practice of IDH1, ATRX, and P53 Immunohistochemistry in Integrated Diagnosis of Adult Diffuse Gliomas: Single Center Study.

Diffuse gliomas exhibit different molecular and genetic profiles with a wide range of heterogeneity and prognosis. Recently, molecular parameters including ATRX, P53, and IDH mutation status or absence or presence of 1p/19q co-deletion have become a crucial part of the diagnosis of diffuse glioma. In the present study, we tried to analyze the routine practice of the above-mentioned molecular markers focusing on the IHC method in cases of adult diffuse gliomas to evaluate their utility in the integrated diagnosis of adult diffuse gliomas. In total, 134 cases of adult diffuse glioma were evaluated. Using the IHC method, 33,12, and 12 cases of IDH mutant Astrocytoma grade 2, 3, 4, and 45 cases of gliobalstoma, IDH wild type, were molecularly diagnosed. By adding the FISH study for 1p/19q co-deletion, 9 and 8 cases of oligodendroglioma grade 2 and 3 also were included. Two IDH mutant cases were negative for IDH1 in IHC but revealed a positive mutation in further molecular testing. Finally, we were not able to incorporate a complete integrated diagnosis in 16/134(11.94%) of cases. The main molecularly unclassified group was histologically high-grade diffuse glial tumors in patients less than 55 years old and negative IDH1 immunostaining. P53 was positive in 23/33 grade 2, 4/12 grade 3, and 7/12 grade 4 astrocytomas, respectively. Four out of 45 glioblastomas showed positive immunostain, and all oligodendrogliomas were negative. In conclusion, a panel of IHC markers for IDH1 R132H, P53, and ATRX significantly improves the molecular classification of adult diffuse gliomas in daily practice and can be used as a tool to select limited cases for co-deletion testing in the low resources area.

Flow Cytometry Identification of Cell Compartments in the Murine Brain.

Glioma can be modelled in the murine brain through the induction of genetically engineered mouse models or intracranial transplantation. Gliomas (oligodendroglioma and astrocytoma) are thought to arise from neuronal and glial progenitor populations in the brain and are poorly infiltrated by immune cells. An improved understanding of oligodendrocytes, astrocytes, and the immune environment throughout tumor development will enhance the analysis and development of brain cancer models. Here, we describe the isolation and analysis of murine brain cell types using a combination of flow cytometry and quantitative RT-PCR strategies to analyze these individual cell populations in vivo.

Oligodendrogliomas tend to infiltrate the frontal aslant tract, whereas astrocytomas tend to displace it.

INTRODUCTION: MR-tractography is increasingly used in neurosurgical practice to evaluate the anatomical relationships between glioma and nearby subcortical tracts. In some patients, the subcortical tracts seem displaced by the glioma, while in other patients, the subcortical tracts seem infiltrated without displacement. At this point, it is unknown whether these different patterns are related to tumor type. The aim of this exploratory study was to investigate whether tumor type is related to the spatial tractography pattern of the frontal aslant tract (FAT) in low-grade gliomas (LGGs). METHODS: In 64 IDH-mutated LGG patients, the FAT was generated using a pipeline for automatic tractography. In 41 patients, the glioma adjoined the FAT, and four blinded reviewers independently assessed the following two dichotomous categories (yes/no): (i) glioma displaces the tract, and (ii) glioma infiltrates the tract. RESULTS: Fisher's exact tests demonstrated strong and significant positive associations between displacement and astrocytomas (p = .002, φ = .497) and infiltration and oligodendrogliomas (p = .004, φ = .484). The interobserver agreement was good for both categories: (i) κ = 0.76 and (ii) κ = 0.71. CONCLUSION: High sensitivity but low specificity for displacement in astrocytomas demonstrates that in the case of an astrocytoma, the tract is most likely displaced, but that displacement in itself is not necessarily predictive for astrocytomas, as oligodendrogliomas may both infiltrate and displace a tract. Overall, these results demonstrate that oligodendrogliomas tend to infiltrate the nearby subcortical tract, whereas astrocytomas only tend to displace it.