High-grade Astrocytomas Research Articles

PATH-09. THE IMPACT OF MISMATCH REPAIR DEFICIENCY ON GLIOMAS IN CHILDREN, ADOLESCENTS, AND YOUNG ADULTS; A MULTI-CENTRIC, COLLABORATIVE STUDY LED BY THE IRRDC AND GLIOMA TASKFORCE

Abstract BACKGROUND Primary mismatch repair deficiency (pMMRD) is a pan-cancer mechanism caused by somatic mutations or inherited as part of Lynch Syndrome (LS) or constitutional mismatch repair deficiency (CMMRD). PMMRD results in universal hypermutation and microsatellite instability leading to chemoradiation resistance but sensitivity to immunotherapy. The prevalence of pMMRD in gliomas of children, adolescents, and young adults (CAYA), and the impact of germline inheritance is unknown. METHODS We harnessed functional genomic tools across population-based (Toronto), and multiple institutional (SJ, CBTN) cancer databases (n=1276) to determine the prevalence, subgroups, and impact of germline mutations in pMMRD gliomas. RESULTS Data from Toronto, SJ and CBTN reveals prevalence of 10%, 5% and 5% in pediatric high-grade gliomas (HGG). Molecularly, pMMRD is absent in gliomas harboring pediatric-type fusions, BRAF-V600E, and histone mutations, but enriched in HGG harboring IDH and TP53 mutations. In AYA (n=660), pMMRD was detected in 5% of IDH-WT and IDH-mutant high-grade astrocytomas, but notably absent in all oligodendrogliomas and other low-grade gliomas. Across this entire CAYA dataset, all except one pMMRD gliomas harbored germline MMR mutations (97%). Strikingly, LS predominated over CMMRD with significant difference in age of glioma onset (LS: 29-years versus CMMRD: 11-years; p< 0.001, IRRDC dataset). Survival analysis (Kaplan-Meier) confirmed the poor overall survival (OS) for pMMRD and other pediatric subtypes of HGG (3-year OS < 25%). In contrast, IDH-mutant pMMRD HGG have significantly worse OS than IDH-mutant non-pMMRD counterparts. Remarkably, immunotherapy significantly improves survival not only in children, but also for AYA patients with refractory pMMRD HGG (3-year OS > 50%). CONCLUSION This large study demonstrates that pMMRD drives a significant proportion of HGG across CAYA with an alarming impact of germline predisposition. Specifically, unrecognized AYA LS patients with MMRD HGG. These findings support universal screening for MMRD in HGG to identify patients for surveillance and immunotherapy.

Synchronous contralateral low-grade oligodendroglioma and high-grade IDH-mutant astrocytoma.

Synchronous contralateral low-grade oligodendroglioma and high-grade IDH-mutant astrocytoma.

Systematic Review of WHO Grade 4 Astrocytoma in the Cerebellopontine Angle: The Impact of Anatomic Corridor on Treatment Options and Outcomes.

Background Despite advances in multimodal oncologic therapies and molecular genetics, overall survival (OS) in patients with high-grade astrocytomas remains poor. We present an illustrative case and systematic review of rare, predominantly extra-axial World Health Organization (WHO) grade 4 astrocytomas located within the cerebellopontine angle (CPA) and explore the impact of anatomic location on diagnosis, management, and outcomes. Methods A systematic review of adult patients with predominantly extra-axial WHO grade 4 CPA astrocytomas was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines through December 2022. Results Eighteen articles were included comprising 21 astrocytomas: 13 exophytic tumors arising from the cerebellopontine parenchyma and 8 tumors originating from a cranial nerve root entry zone. The median OS was 15 months with one-third of cases demonstrating delayed diagnosis. Gross total resection, molecular genetic profiling, and use of ancillary treatment were low. We report the only patient with an integrated isocitrate dehydrogenase 1 (IDH-1) mutant diagnosis, who, after subtotal resection and chemoradiation, remains alive at 40 months without progression. Conclusion The deep conical-shaped corridor and abundance of eloquent tissue of the CPA significantly limits both surgical resection and utility of device-based therapies in this region. Prompt diagnosis, molecular characterization, and systemic therapeutic advances serve as the predominant means to optimize survival for patients with rare skull base astrocytomas.

Proton MR spectroscopy shows improved performance to segregate high-grade astrocytoma subgroups when defined with the new 2021 World Health Organization classification of central nervous system tumors.

The 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors prioritizes isocitrate dehydrogenase (IDH) mutation to define tumor types in diffuse gliomas, in contrast to the 2016 classification, which prioritized histological features. Our objective was to investigate the influence of this change in the performance of proton MR spectroscopy (1H-MRS) in segregating high-grade diffuse astrocytoma subgroups. Patients with CNS WHO grade 3 and 4 diffuse astrocytoma, known IDH mutation status, and available 1H-MRS were retrospectively retrieved and divided into 4 groups based on IDH mutation status and histological grade. Differences in 1H-MRS between groups were analyzed with the Kruskal-Wallis test. The points on the spectrum that showed the greatest differences were chosen to evaluate the performance of 1H-MRS in discriminating between grades 3 and 4 tumors (WHO 2016 defined), and between IDH-mutant and IDH-wildtype tumors (WHO 2021). ROC curves were constructed with these points, and AUC values were calculated and compared. The study included 223 patients with high-grade diffuse astrocytoma. Discrimination between IDH-mutant and IDH-wildtype tumors showed higher AUC values (highest AUC short TE, 0.943; long TE, 0.864) and more noticeable visual differences than the discrimination between grade 3 and 4 tumors (short TE, 0.885; long TE, 0.838). Our findings suggest that 1H-MRS is more applicable to classify high-grade astrocytomas defined with the 2021 criteria. Improved metabolomic robustness and more homogeneous groups yielded better tumor type discrimination by 1H-MRS with the new criteria. The 2021 World Health Organization classification of brain tumors empowers molecular criteria to improve tumor characterization. This derives in greater segregation of high-grade diffuse astrocytoma subgroups by MR spectroscopy and warrants further development of brain tumor classification tools with spectroscopy. • The new 2021 updated World Health Organization classification of central nervous system tumors maximizes the role of molecular diagnosis in the classification of brain tumors. • Proton MR spectroscopy performs better to segregate high-grade astrocytoma subgroups when defined with the new criteria. • The study provides additional evidence of improved metabolic characterization of brain tumor subgroups with the new criteria.

JS08.4.A LINEAR GRADING COEFFICIENT REVEALS EMBRYONIC DEVELOPMENT GENE SIGNATURE AS TREATMENT-INDEPENDENT PROGNOSTIC FACTOR IN IDH-MUTANT ASTROCYTOMA

Abstract BACKGROUND Diffuse gliomas are classified into grade II/III and grade IV IDH-mutant (IDHmt) astrocytoma based on histology and homozygous deletion of the CDKN2AB locus, according to the 2021 WHO classification. There is considerable variation in prognosis within these classification groups and we therefore sought to identify features that might aid further tumor grading. MATERIAL AND METHODS RNA sequencing was performed on IDHmt astrocytomas included in the CATNON trial and overlaid with previously generated genome-wide methylation data. This dataset was extended by multi-omics data from the TCGA and GLASS-NL studies, where the latter was used for validation. For all datasets, only IDHmt astrocytomas were selected. We defined a linear grading coefficient (LGC) based on calibrated DNA methylation-based probability scores and performed differential gene expression (DGE) regression analysis on the LGC. Statistical analyses were intersected across the CATNON and TCGA cohorts ("discovery set") and validated on the primary-recurrent GLASS-NL dataset. Single-nucleus RNA-sequencing (snRNAseq) data of high-grade IDHmt astrocytomas was used to explore the source of expression signals. RESULTS DGE regression analysis revealed that higher-grade IDHmt tumors (high LGC) exhibited mRNA upregulation of key embryonic developmental transcription factors (HOXA/C/D, NKX, PAX, and TBX). Although the vast majority of CpG sites in LGC high tumors were hypomethylated, homeobox genes were strongly hypermethylated in our discovery set. All HOX gene clusters showed gene-ordered (differential) expression where e.g. HOXD10>D9>D8>D4>D1 and HOXA3>A7>A9>A13 suggesting derepression of enhancer sequences up/downstream of the gene cluster. Our expression-based gene signature was positively correlated with, but not limited to, the G-CIMP-low subtype and homozygous CDKN2AB deletion. More than half of the genes from the HOX gene family were part of our signature. Our embryonic development signature was prognostic (log-rank test) on both the discovery (CATNON: p < 0.0005, TCGA: p < 0.0005) and validation set (GLASS-NL: p < 0.005). As our signature was developed on molecular data from the first resection its prognostic value is treatment-independent. SnRNAseq on high-grade IDHmt astrocytomas indicated expression of embryonic development genes from tumor cells, which was not restricted to cells from the stemness program. CONCLUSION Our study highlights upregulation of embryonic development genes as potential molecular mechanism associated with the malignant progression of IDH-mutant astrocytomas.

P20.12.B DNA METHYLATION PROFILING OF ADULT SPINAL GLIAL TUMOURS; RESULTS FROM A LARGE SINGLE CENTRE STUDY

Abstract BACKGROUND Glial tumours can occur in any central nervous system location, including the spinal cord. Although rare, spinal gliomas can represent a significant diagnostic challenge and are recognised as separate tumour types in the WHO classification. MATERIAL AND METHODS This study used DNA methylation profiling to characterise adult spinal glial tumours from a large neurosurgical centre, exploring relative frequencies, and the value of this technique in diagnostic workflows. A search in our laboratory information management system (2006-2021) identified 116 tumours, from patients aged 17.2-79.2 years. Diagnoses included ependymomas (all grades/subtypes) and other high- or low-grade gliomas (HGG/LGG). Extrinsic tumours (metastases, meningiomas, schwannomas) were excluded. DNA underwent methylation profiling (Illumina EPIC BeadArrays, n=116). iDat files were processed using the brain tumour classifier (MNP v12.5 R package), classifying cases against a reference cohort (n=2,800). Longitudinal (n=8) and poor QC cases (n=3) were excluded. RESULTS 83% (n=87) classified as an ependymoma (myxopapillary ependymoma (EPN_MPE, n=44), spinal ependymoma (n=43), spinal subependymoma (n=1)). We identified HGGs that were not diagnosed histologically (diffuse midline glioma, H3 K27-altered (n=2), high-grade astrocytoma with piloid features (n=1)) and 41% of cases (n=18/44) diagnosed histologically as an ependymoma, CNS WHO grade 2, classified as EPN_MPE. LGGs were less frequent (pilocytic astrocytoma (n=3), pleomorphic xanthoastrocytoma (n=1), rosette-forming glioneuronal tumour (n=1)). 9% (n=9) did not classify with existing methylation classes. Copy number analysis revealed subtype-specific changes, including prognostic alterations. CONCLUSION In conclusion, this single-centre study highlights the crucial role of DNA methylation profiling as part of diagnostic workflows for spinal glial tumours.

JS09.8.A COMPARATIVE PROGNOSTIC VALUE OF O-(2-[18F]-FLUOROETHYL)-L-TYROSINE PET IMAGING AND DCE MRI BLOOD VOLUME IMAGING IN PATIENTS WITH SUSPECTED RECURRENT IDH-WILDTYPE HIGH-GRADE GLIOMA

Abstract BACKGROUND Quantitative blood volume (BV) imaging using dynamic T1-weighted contrast enhanced (DCE) perfusion MRI may be of diagnostic value in patients with suspected recurrent high-grade glioma, but the association of DCE BV measurements with survival is not known. The aim of the study was to compare the prognostic information of DCE BV measurements with that of O-(2-[18F]-fluoroethyl)-L-tyrosine ([18F]FET) PET imaging in treated IDH wildtype high-grade astrocytoma and glioblastoma (2016 WHO classification). MATERIAL AND METHODS A total of 94 hybrid [18F]FET PET/MRI scans with DCE from unique adult patients were retrospectively analysed. Scans were obtained after surgery/biopsy (n=94) and radiotherapy (n=93) due to variable suspicion of residual or progressive disease. In each scan the visually BV positive (VOLBV), the [18F]FET PET avid (VOLFET) and the contrast-enhancing (VOLCE) volumes were delineated, and fractional tumour volumes (fVOL) within VOLCE, as well as maximal BV (BVmax) and maximal [18F]FET tumour-to-background ratio (TBRmax) were determined. Accuracy for prediction of 6-month progression free survival and 1 year overall survival were assessed by logistics regression. Associations with overall survival were assessed for each parameter by Cox proportional hazard analysis. RESULTS In a univariate analysis, adjusted for age and MGMT, both VOLCE, and all [18F]FET and DCE BV derived metrics were predictive of both 6 month progression free survival, 1 year survival and overall survival. ROC AUC for prediction of 6 month progression free survival and 1 year overall survival tended to be higher for [18F]FET derived metrics, but ROC AUC values were not significantly different between any [18F]FET and DCE BV derived metrics. In Cox models for overall survival (adjusting for age, MGMT and VOLCE) only TBRmax and VOLBV had independent prognostic value among [18F]FET PET and DCE BV derived metrics, respectively. In a final model including both TBRmax and VOLBV, only TBRmax remained significant.. CONCLUSION DCE BV and [18F]FET PET derived metrics provides prognostic information independent of age, MGMT status and contrast enhancing tumour volume in treated glioblastoma, with volume of increased BV and [18F]FET TBRmax providing strongest associations with overall survival. Accounting for functional imaging biomarkers may be important in balancing future randomized clinical trials.

Molecular profiling of pre- and post-treatment pediatric high-grade astrocytomas reveals acquired increased tumor mutation burden in a subset of recurrences

Diffuse gliomas are a heterogeneous category of primary central nervous system tumors. Due to their infiltrative growth precluding complete surgical resection, most diffuse high-grade gliomas are treated with adjuvant chemotherapy and radiation. Recurrent/progressive diffuse gliomas may show genetic differences when compared to the primary tumors, giving insight into their molecular evolution and mechanisms of treatment resistance. In adult-type diffuse gliomas with or without isocitrate dehydrogenase gene mutations, tumor recurrence/progression can be associated with mutations in genes encoding DNA mismatch repair proteins, leading to a dramatic increase in tumor mutation burden. This phenomenon is closely linked to treatment with the DNA alkylating agent temozolomide, a mainstay of adult diffuse glioma chemotherapeutic management. Post-treatment mismatch repair deficiency and acquired high tumor mutation burden is relatively unexplored in pediatric patients who have recurrent high-grade gliomas. Here, we report a molecular and histological analysis of an institutional cohort of eleven pediatric patients with paired initial and recurrent high-grade astrocytoma samples with intervening temozolomide treatment. We identified three cases with evidence for increased tumor mutation burden at recurrence, including two cases of diffuse hemispheric glioma H3 G34-mutant (one previously reported). We also show that molecular analysis by next-generation DNA sequencing and DNA methylation-based profiling enabled an integrated diagnosis per 2021 World Health Organization criteria in 10 of 11 cases (91%). Our findings indicate that increased tumor mutation burden at post-treatment recurrence is relevant in pediatric-type diffuse high-grade gliomas. Diffuse hemispheric glioma H3 G34-mutant may be particularly susceptible to this phenomenon.

Role of Wilms’ tumor 1 in diagnosis and grading of astrocytomas

Background: Wilms’ tumor 1 (WT1) mutation has recently been detected in gliomas. Growing data indicate that WT1 mutation plays a causal role in gliomagenesis and is overexpressed in most glioblastomas. Emerging immunotherapy targeting WT1 has shown to be effective in resistant glioblastomas in clinical trials. WT1 expression and its potential utility in various grades of astrocytomas is still unclear and needs further elucidation. The evaluation of WT1 can be done by molecular or immunohistochemical methods. As immunohistochemistry is easier with wider routine use, immunoexpression of this biomarker was studied. Aims and Objectives: This study aimed to evaluate WT1 immunoexpression across different histological grades of astrocytomas and differentiate low-grade astrocytomas from reactive astrogliosis. Materials and Methods: This was an observational prospective study on 54 cases of astrocytomas. Results: In the present study a total of 54 cases have been diagnosed as astrocytomas. Grade IV was the most common (31%) followed by grade II (44%). WT1 score correlated with histological tumor grades (P<0.001) with a higher score in a higher grade. It was also observed that different tumor grades depicted two distinct expression patterns. WT1 score and pattern were valuable in differentiating high- and low-grade astrocytomas. Conclusion: This study supports the oncogenic role of WT1 in astrocytomas. WT1 was found to be valuable in distinguishing different grades of astrocytomas. The scoring and distinctive patterns of WT1 can aid in distinguishing high-grade and low-grade astrocytomas. However, one needs to be careful in pilocytic astrocytomas in which there is a mixed expression. WT1, therefore, appears to be an attractive immunohistochemistry (IHC) marker to be used concomitantly with other IHC markers in astrocytomas. In addition, the frequent expression of WT1 in astrocytomas supports its promising role in immunotherapy and its potential to guide patient selection for targeted immunotherapy.

Quality by design engineered, enhanced anticancer activity of temozolomide and resveratrol coloaded NLC and brain targeting via lactoferrin conjugation in treatment of glioblastoma

The most dangerous type of high-grade astrocytoma is glioblastoma multiforme. The objective of the work was to engineer lactoferrin conjugated temozolomide and resveratrol co-loaded NLC for the treatment of glioblastoma using intranasal delivery for brain targeting. Synergistic activity of temozolomide and resveratrol was determined using combination index method and 1:1 ratio was selected. QbD approach was used to formulate and optimize NLC, with minimum particle size, maximum transmittance and entrapment efficiency using Central Composite Rotable Design (CCRD) method. The optimized LTR-NLC had desired average particle size (209.3 nm), narrow PDI along, high percentage transmittance (>95%) and better entrapment efficiency (95.26% of TEM and 87.59% of RES). From ex-vivo permeation studies it was found that the permeation at 24 h was 77.43 %, and 88.55 % from LTR-NLC and 25.76 % and 31.10% from suspension for resveratrol and temozolomide respectively. In comparison to drug suspension, NLC had nearly 3-fold increase in drug penetration. IC50 value was also significantly better in the groups treated with LTR-NLC. Hence it can be concluded that LTR-NLC may be an effective formulation for the treatment of glioblastoma, according to the findings of this investigation.

Usefulness and limitations of intraoperative pathological diagnosis using frozen sections for spinal cord tumors

BackgroundIntraoperative pathological diagnosis has a major influence on the intra- and postoperative management of spinal cord tumors. Thus, the aim of this study was to assess the reliability of intraoperative pathological diagnosis for spinal cord lesions by comparing it with the final pathological diagnosis and to determine its usefulness and limitations. MethodThree-hundred and three consecutive patients (mean age, 53.9 years) with neoplastic spinal cord lesions who underwent initial surgery between 2000 and 2021 were included. The anatomical locations of the spinal cord tumors and the implementation rate of intraoperative pathological diagnosis in each tumor type were evaluated. As the primary outcome, we determined the concordance rates between the intraoperative pathological diagnosis and the final diagnosis. When the intraoperative pathological diagnosis and final diagnosis were the same, the diagnosis was defined as a “match.” Otherwise, the diagnosis was defined as a “mismatch.” ResultsThe overall implementation rate of intraoperative pathological diagnosis was 53%, with implementation rates of 71%, 45%, 47%, and 50% for intramedullary, intradural extramedullary, extradural, and dumbbell tumors, respectively. The overall concordance rate was 87.6%, with concordance rates of 80%, 95%, 75%, and 90% for intramedullary, intradural extramedullary, extradural, and dumbbell tumors, respectively (p < 0.05). The diagnoses of ependymomas, low-grade astrocytomas, and high-grade astrocytomas was occasionally difficult among intramedullary tumors. Among intradural extramedullary tumors, differentiation between grade 1 meningioma and high-grade meningioma was difficult using intraoperative pathological diagnosis. ConclusionsSurgeons must recognize the lower accuracy of intraoperative pathological diagnosis for intramedullary and extradural lesions and make a final decision by considering the intraoperative gross findings, preoperative clinical course, and imaging.

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.

TIPS-09 FIRST-IN-HUMAN PHASE 1 TRIAL OF THE SAFETY, TOLERABILITY, PHARMACOKINETICS, AND PRELIMINARY ANTI-TUMOR ACTIVITY OF WSD0922-FU (NCT04197934): TRIAL IN PROGRESS

Abstract WSD0922-Fu is an oral, central nervous system (CNS)-penetrant, small molecule, ATP non-competitive, reversible EGFR inhibitor which potently inhibits EGFR aberrations specific to non-small cell lung cancer (NSCLC) and high-grade astrocytoma (HGA). MC1914 (NCT04197934, sponsored by Wayshine Biopharma and FDA OOPD) is a first-in-human phase 1 dose-escalation trial investigating the safety and tolerability of WSD0922-Fu in patients with EGFR aberrant recurrent HGA and NSCLC. Adult patients with either recurrent EGFR mutant NSCLC with CNS metastases or recurrent EGFR mutant and/or EGFR amplified HGA were initially treated with oral WSD0922-FU, with doses escalated in cohorts based on a standard 3 + 3 design to determine the maximum tolerated dose (MTD). After establishing the MTD, this trial has now activated three dose expansion cohorts. Two of these cohorts evaluate different dose/schedule strategies in independent populations. The NSCLC cohort includes patients with EGFR mutant NSCLC and CNS metastases, and examines the safety, tolerability, plasma pharmacokinetics and preliminary efficacy of continuous WSD0922-Fu dosing (twice daily, seven days per week). The HGA cohort includes patients with EGFRvIII mutant HGA at first recurrence after prior radiation/temozolomide and examines the impact of higher doses of WSD0922-Fu administered intermittently (twice daily, five days per week). The HGA cohort also includes a food-effect study which evaluates the effect of the fed and fasted states on plasma PK. The third cohort (Brain tumor penetration cohort) includes patients with HGA (any EGFR mutation and/or EGFR amplification) who need a surgical resection for recurrent disease. Patients enrolled will be treated pre-operatively with WSD0922-Fu for five days, and tumor PK/PD will be examined in samples obtained from image-registered brain tumor biopsies. WSD0922-Fu therapy will be resumed after post-operative recovery. Patient enrollment to all three dose expansion cohorts is ongoing.

An Unusual Case of Atypical Meningioma Mimicking as High-Grade Astrocytoma: A Case Report

An Unusual Case of Atypical Meningioma Mimicking as High-Grade Astrocytoma: A Case Report

The application of cannabidiol in the treatment of glioblastoma

Glioblastoma multiforme (GBM), a high-grade astrocytoma, is an incurable brain tumor associated with genetic heterogeneity and dysregulated signaling pathways. As alternations of the endocannabinoid system have been demonstrated in GBM cells, the substances affecting its key elements may potentially inhibit tumor progression. Preclinical models indicate that CBD inhibits GBM tumor growth by inhibiting cellular proliferation, migration, and invasion but also promotes autophagy and apoptosis of tumor cells. Moreover, clinical trials indicate the safety and positive results regarding the survival of GBM patients upon cannabinoids treatment. Nevertheless, more human clinical trials with large sample sizes are urgently needed to implement cannabinoids, including CBD, into standard GBM treatment.

“A tumour registry initiative”

BackgroundPublished literature on epidemiological profile of paediatric brain tumours in India is limited. Aim: To present a retrospective analysis of the histological spectrum of 158 paediatric age group central nervous system tumours operated in a single tertiary care hospital in Coastal South India between January 2015 and December 2021. Material and methodsRetrospective analysis of the data regarding frequencies of various primary brain tumours among 158 paediatric patients (<18 years of age). The tumours were categorised according to the revised 4th edition of World Health Organization (WHO) classification of tumours of the Central Nervous system. ResultsPaediatric CNS constituted 8.5% of total intracranial tumours (158/1860) operated in the study period. The mean age of the patients was 10.2 years and a definite male predominance was noted (1.54:1) Astrocytomas, glioneuronal tumours, and neuronal tumours constituted the majority (72/158; 45.6%) followed by embryonal tumours (31/158; 19.6%) and craniopharyngiomas(24/158; 15.4%).Of the glial neoplasms majority were pilocytic and other astrocytic tumours(41.6%), followed by mixed neuroglial tumours (19.4%), diffuse high grade astrocytomas (Grade III/IV) (11.1%), diffuse low -grade astrocytomas (Grade II) (9.7%) and ependymomas (13.8%). Our series also included six meningiomas (3.8%), five germ cell tumours (3.16%), four nerve sheath tumours (2.53%), two choroid plexus tumours (1.26%), two pineal parenchymal tumours (1.26%) and one metastasis from a soft tissue sarcoma from the thigh. Supratentorial tumours (58.2%) were more common than posterior fossa (34.6%) and spinal tumours (7.6%) and visual pathway gliomas accounted for 5.6% of all our tumours. ConclusionsPaediatric central nervous system tumours are more common in boys and in the second decade of life. Astrocytomas are the most common paediatric brain tumours followed by medulloblastomas and craniopharyngiomas. Pediatric tumours affect the supratentorial compartment more often than the infratentorial compartment. The profile of paediatric brain tumours in our series is similar to that reported from other Indian centres as well as most western literature.

Intra- and Intertumoral Microglia/Macrophage Infiltration and Their Associated Molecular Signature Is Highly Variable in Canine Oligodendroglioma: A Preliminary Evaluation.

The goal of this study was to define the glioma-associated microglia/macrophage (GAM) response and associated molecular landscape in canine oligodendrogliomas. Here, we quantified the intratumoral GAM density of low- and high-grade oligodendrogliomas compared to that of a normal brain, as well as the intratumoral concentration of several known GAM-derived pro-tumorigenic molecules in high-grade oligodendrogliomas compared to that in a normal brain. Our analysis demonstrated marked intra- and intertumoral heterogeneity of GAM infiltration. Correspondingly, we observed significant variability in the intratumoral concentrations of several GAM-associated molecules, unlike what we previously observed in high-grade astrocytomas. However, high-grade oligodendroglioma tumor homogenates (n = 6) exhibited an increase in the pro-tumorigenic molecules hepatocyte growth factor receptor (HGFR) and vascular endothelial growth factor (VEGF), as we observed in high-grade astrocytomas. Moreover, neoplastic oligodendrocytes displayed robust expression of GAL-3, a chimeric galectin implicated in driving immunosuppression in human glioblastoma. While this work identifies shared putative therapeutic targets across canine glioma subtypes (HGFR, GAL-3), it highlights several key differences in the immune landscape. Therefore, a continued effort to develop a comprehensive understanding of the immune microenvironment within each subtype is necessary to inform therapeutic strategies going forward.

HGG-20. NOVEL PAEDIATRIC CASE OF A SPINAL HIGH-GRADE ASTROCYTOMA WITH PILOID FEATURES IN A PATIENT WITH NOONAN SYNDROME

Abstract Noonan Syndrome (NS) is a genetic condition, known to be associated with low grade central nervous system tumours in children but only very rarely associated with high-grade gliomas. Here we describe the first reported case of a spinal high-grade astrocytoma with piloid features (HGAP) in a child with NS. This case presented as a diagnostic and treatment dilemma, prior to comprehensive molecular profiling with whole-genome germline and tumour sequencing, tumour transcriptome sequencing and DNA methylation analysis. The methylation profile was a strong match for HGAP and was critical to establish this child’s diagnosis, as this is an essential diagnostic criteria for confirmation of this relatively new tumour group. Sequencing results identified activation of the MAPK signalling pathway with somatic variants in FGFR1 and NF1 and the previously known germline pathogenic variant in PTPN11. The somatic molecular profile was consistent with those previously reported in other HGAP case series and reports, whereas the germline finding has not been previously described in individuals with this tumour type. This patient’s molecular profile adds to the small group of paediatric cases reported in the literature, continuing to expand our understanding of this new WHO diagnostic category. Confirmation of this rare diagnosis was critical to this child’s management and targetable aberrations were identified, providing alternative therapeutic options. The therapeutic targets included known drivers within the MAPK pathway, but also changes not previously associated with HGAP such as differential expression of VEGFA and PD-L1. Together this case underscores the power of precision medicine from a diagnostic, therapeutic and clinical management perspective, and describes an association between HGAP and NS which has not previously been reported.

First-in-human phase 1 trial of the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of WSD0922-Fu: Initial report from dose escalation cohort.

3109 Background: WSD0922-Fu is an oral, central nervous system (CNS)-penetrant, small molecule, ATP non-competitive, reversible EGFR inhibitor which potently inhibits EGFR aberrations specific to non-small cell lung cancer (NSCLC) and high-grade astrocytoma (HGA). We report initial results of a first-in-human phase 1 dose-escalation trial (NCT04197934) in patients with EGFR aberrant recurrent HGA and NSCLC. Methods: Adult patients with either recurrent EGFR mutant NSCLC with CNS metastases or recurrent EGFR mutant and/or EGFR amplified HGA were enrolled. WSD0922-Fu was orally administered, and dose escalated in cohorts based on a standard 3+3 design to determine the maximum tolerated dose (MTD). Toxicities were graded per CTCAE v5.0 and preliminary efficacy was based on modified RANO criteria or RECIST 1.1 as appropriate. Results: 25 patients (17 HGA, 8 NSCLC) were enrolled and treated in six cohorts (40 mg once daily to 320 mg twice daily, 28-day cycles). The median age was 57 years (range 39-75 years). 24% were female and 36% were ECOG 0. For patients with HGA, all patients were previously treated with radiation and temozolomide; the median number of prior lines of systemic therapy was 1 (range 1-4). For patients with NSCLC, all patients were previously treated with an EGFR inhibitor (prior osimertinib 88%); the median number of prior lines of systemic therapy was 1.5 (range 1-6). The median duration of exposure to WSD0922-Fu among all patients was 54 days (range 2-258 days). The most common (≥25%) treatment-related adverse events included fatigue (68%), acneiform rash (68%), diarrhea (52%), nausea (48%) and pruritis (28%). The frequency of severe AEs was dose dependent. The most common Grade 3+ AEs (≥10%) included lymphopenia (16%), acneiform rash (12%), headache (12%) and diarrhea (12%). The MTD was defined as 160 mg twice daily. At Cycle 1 Day 15 for patients treated at this dose level, the mean terminal elimination half-life (%CV) in the plasma was 31.6 h (102%) (median 14.5 h; range 6.2-78.7 h). The mean Cmax, Tmax, oral clearance at steady state, and AUC (0-12 h) (%CV) were 4513 ng/mL (50%), 2.0 hr (69%), 6.9 L/hr/m2 (42%), and 28084 h*ng/mL (52%), respectively. Oral clearance at steady state was inversely related with dose, suggesting either inhibition or saturation of clearance processes. Among patients treated at MTD or higher dose levels and with available response data, 100% (5/5) of patients with NSCLC demonstrated clinical benefit (SD + PR) while 60% of patients had partial responses (intracranial and extracranial). Furthermore, prolonged stable disease (9 cycles) was observed in a patient with EGFRvIII mutant GBM. Conclusions: The MTD for WSD0922-Fu monotherapy is 160 mg BID. Preliminary efficacy was observed in patients with osimertinib-resistant NSCLC and EGFRvIII mutant HGA. Enrollment to expansion cohorts is ongoing. Clinical trial information: NCT04197934 .

Establishment and characterization of two novel patient-derived lines from canine high-grade glioma.

High-grade glioma is an aggressive cancer that occurs naturally in pet dogs. Canine high-grade glioma (cHGG) is treated with radiation, chemotherapy or surgery, but has no curative treatment. Within the past eight years, there have been advances in our imaging and histopathology standards as well as genetic charactereization of cHGG. However, there are only three cHGG cell lines publicly available, all of which were derived from astrocytoma and established using methods involving expansion of tumour cells in vitro on plastic dishes. In order to provide more clinically relevant cell lines for studying cHGG in vitro, the goal of this study was to establish cHGG patient-derived lines, whereby cancer cells are expanded in vivo by injecting cells into immunocompromized laboratory mice. The cells are then harvested from mice and used for in vitro studies. This method is the standard in the human field and has been shown to minimize the acquisition of genetic alterations and gene expression changes from the original tumour. Through a multi-institutional collaboration, we describe our methods for establishing two novel cHGG patient-derived lines, Boo-HA and Mo-HO, from a high-grade astrocytoma and a high-grade oligodendroglioma, respectively. We compare our novel lines to G06-A, J3T-Bg, and SDT-3G (traditional cHGG cell lines) in terms of proliferation and sensitivity to radiation. We also perform whole genome sequencing and identify an NF1 truncating mutation in Mo-HO. We report the characterization and availability of these novel patient-derived lines for use by the veterinary community.