Citations

Abstract The 2021 WHO classification redefined glioblastoma IDH-wildtype (GBM), integrating histopathological and tumor molecular features. Diffuse astrocytic glioma lacking histologic features of necrosis and microvascular proliferation are classified as (molecular) GBM if the tumor is IDH- and H3-wildtype and has one or more additional tumor molecular alterations: TERT promoter mutation, EGFR amplification, or +7/-10. Due to the absence of histopathological features of classic GBM and presentation without enhancement on MRI in approximately 50% of cases, molecular GBM frequently resemble low-grade IDH-mutant gliomas. We hypothesized that MRI-based deep learning models could distinguish IDH-mutant glioma from molecular GBM. We retrospectively identified 97 individuals with molecular GBM, who were matched to 97 individuals with IDH-mutant glioma by age, sex, year of diagnosis, and enhancement on MRI. Of the 97 IDH-mutant gliomas, 51% were 1p/19q codeleted, 42% grade 2, 47% grade 3, and 10% grade 4. Preoperative postcontrast T1-weighted (T1C) and T2-weighted (T2) MRI sequences were used to train a 3D-DenseNet121 model. The model was validated on an independent prospective set of 150 IDH-mutant gliomas and 71 molecular GBM. The MRI-based deep learning model achieved an area under the receiver operator curve (AUC) of 0.75 (95% CI: 0.68-0.82) in the prospective validation set. Sex-stratified AUCs were 0.72 (95% CI: 0.59-0.85) for females and 0.76 (95% CI: 0.68-0.85) for males. Age stratified AUCs were 0.71 (95% CI: 0.60-0.83) for patients under 55 years of age and 0.64 (95% CI: 0.50-0.79) for patients older than 55. These results suggest that discriminative MRI features of IDH-mutant glioma and molecular GBM exist and can be identified from deep learning models. However, radiographic ambiguity exists and underscores the need for further optimization of the deep learning architecture or by integrating additional non-invasive modalities. For example, future work entails integrating germline variants into the model, including rs55705857, which is a causal variant for IDH-mutant glioma. With further validation and integration of multi-modal data, a noninvasive tool may support more personalized decision-making.

Abstract IDH-wildtype diffuse astrocytic gliomas with lower-grade histological features alongside specific genomic alterations (e.g., TERT promoter mutation, EGFR amplification, gain Chr7/loss Chr10) are presently diagnosed as glioblastoma, IDH-wildtype (GBM) under WHO 2021 criteria. Previous analyses categorized these into “early/evolving” or “surgically undersampled” GBMs. However, it remains unclear whether these tumors share identical clinical and prognostic features with histologic GBM. Data from IDH-wt molecular GBMs across six institutions were aggregated. Astrocytic IDH-wt tumors of any grade that lacked necrosis or microvascular proliferation on initial histopathology yet exhibited molecular alterations consistent with WHO 2021 GBM diagnosis, were included. Recursive partitioning analysis (RPA) was used to categorize patients into risk groups based on overall survival (OS). Among the 264 patients included, the median age was 60 years (IQR: 51-67), with 162 (61%) being male. Additionally, 210 (80%) were diagnosed since 2016, and 216 (82%) received chemoradiation plus adjuvant temozolomide (GBM-SOC). The median follow-up period was 3.9 years (95% CI: 3.4, 4.6). Identified univariate risk factors for worse survival included older age, biopsy-only status, EGFR amplification, absence of initial adjuvant treatment, low post-operative KPS, and tumor histologic grade of 3. RPA divided patients into four distinct survival groups (p<0.0001). The “best” risk group comprised lower grade (<=2) tumors (n=58, median OS (mOS): 40 months (95% CI: 33, NA)). The “second best” group included Grade 3 patients receiving GBM-SOC without steroids during initial RT (n=139, mOS: 25 months (95% CI: 22, 28)). The “second worst” group encompassed Grade 3 patients who were on steroids during initial RT while receiving GBM-SOC (n=38, mOS: 15 months (95% CI: 13, 20)). The “worst” group contained Grade 3 tumors that had not undergone SOC (n=29, mOS: 9 months (95% CI: 4, 26)). These data show that histologic features and treatment are strong indicators of patient outcomes.

Abstract BACKGROUND The phase III ECOG-ACRIN E3F05 trial tested whether combined therapy with radiation and concomitant followed by adjuvant temozolomide is more effective than radiation alone in patients with grade II gliomas. The study incorporated 1p/19q analysis but predated assessment of IDH mutational status. We previously reported that the addition of temozolomide to radiotherapy significantly improved overall survival in grade II gliomas, with similar hazard ratios in co-deleted (0.56) and non-codeleted (0.53) tumors. Herein we incorporate the results of DNA methylation profiling to examine outcomes in IDHmt, non-codeleted subjects as well as co-deleted ones. METHODS All 172 subjects underwent 1p/19q co-deletion analysis as a stratification factor, 1p and 19q deletion analysis was performed on formalin-fixed paraffin-embedded (FFPE) gliomas by Fluorescent In Situ Hybridization (FISH) following standard methods, 97/172 (56.3%) had tissue with 60% or more tumor content available for DNA methylation profiling using Heidelberg classifier v12 and Bethesda Classifier 2.0 to ascertain classification as IDH mutant glioma and alternative evaluation of 1p/19q co-deletion status. RESULTS Of the 172 subjects, 74 (43.0%) had 1p/19q codeletion by FISH, 38 (22.1%) were IDHmt without codeletion, 14 (8.1%) were IDHwt, and 46 (26.7%) were non-codeleted with unknown IDH status (these include n=4 pts originally classified as 1p/19q undetermined). With a median follow-up of 130 months, the addition of TMZ to RT improved OS in patients with IDHmt, non-codeleted tumors (HR 0.15 (0.03-0.74)) and 10-year OS from 39% to 80%. In codeleted tumors, the addition of TMZ improved OS (HR 0.51 (0.19-1.42)) and 10-year OS from 68% to 90%. CONCLUSION The addition of temozolomide to radiation improves overall survival in both co-deleted and IDHmt, non-co-deleted grade II gliomas.

Abstract The WHO 2021 classification of central nervous system tumors incorporated molecular markers to better define diffuse glioma subgroups. We analyzed array-based copy number, targeted next-generation sequencing, germline genotyping, and Illumina EPIC array methylation data from 404 primary IDH-mutant astrocytomas to further understand the relationship between copy number and outcomes. Loss of chromosome arm 13q was associated with poor overall survival after adjusting for age, sex, tumor grade, and treatment status (hazard ratio [HR]=2.04 (95% confidence interval: 1.25-3.33), p=0.004). Chromosome 13q loss was also significantly associated with the total number of copy number alterations (p<0.001). Loss of arm 11p was associated with poor survival in the adjusted analysis (HR=2.29 (1.38-3.79), p=0.001). Unsupervised clustering of the raw copy number data identified 12 clusters, where each cluster was defined by distinct copy number alteration(s). Clusters that contained 13q loss exhibited worse overall survival compared to other clusters. The clusters were significantly associated with age at diagnosis (p=0.015), tumor grade (p<0.001) and copy number complexity (p<0.001). The clusters with a high proportion of grade 4 tumors and with the highest complexity had the poorest overall survival. These findings highlight the prognostic relevance of chromosome 13q and 11p losses in IDH-mutant astrocytomas and support the integration of additional copy number alterations into molecular classification frameworks of IDH-mutant astrocytomas to improve risk stratification and patient management.

Abstract Pediatric high-grade gliomas (pHGG) are aggressive primary brain neoplasms with a dismal prognosis, making them the leading cause of brain tumor-related deaths in children. pHGGs occur in specific anatomical locations at specific ages underscoring their origin in neurodevelopment and the critical importance of the brain tumor microenvironment. Many pHGGs originate from oligodendroglial precursor cells (OPCs) and, like OPCs, neuronal activity promotes the proliferation of pHGGs. Neuronal activity drives pHGG growth through electrochemical communication with pHGG cells. In turn, pHGGs increase neuronal excitability and remodel functional neural circuits. The interconnected network of glioma cells and neurons is fundamental to pHGG progression. Using single-nuclei RNA sequencing of mice harboring murine H3K27M-altered Diffused Midline Glioma (DMG), we observed gene expression changes indicating an increase in axonogenesis processes in glioma-associated neurons (GANs), primarily driven by EphA signaling. EphA4, EphA5, and EphA7 are overexpressed in GANs while the ligand, EphrinA1, is overexpressed in H3K27M gliomas. Performing in vitro neurite outgrowth and co-culture assays, we observed increased axonogenesis in neurons in the presence of DMG cells and DMG-conditioned media. We developed a two-color in vivo imaging method to study neuron-glioma interactions over time in freely behaving mice enabling us to record the frequency, pattern, and synchronicity of calcium transients in neurons, glioma cells, and their coactivity, giving us a comprehensive view of the changes in neuron-glioma circuit dynamics over time. We have observed increasing neuronal activity and synchronicity throughout the disease. We have also observed that gliomas also exhibit increased levels of activity and synchronicity as the tumor progresses. We verified our findings through longitudinal in vivo local field potential recordings, finding an increase in all power bands, especially in high-gamma activity over time. Ongoing experiments will test how glioma-induced axonogenesis contributes to the observed evolution of malignant circuit dynamics over time. Taken together, our data shows as gliomas progress, the neuron-glioma malignant circuitry evolves through axonogenesis driven by EphA signaling.

Abstract BACKGROUND Tumor Treating Field (TTF) therapy exerts antineoplastic effects through application of alternating electrical fields that disrupt mitotic machinery and induce DNA damage and activation of cell cycle checkpoints. However, despite extensive utilization in clinical practice for the management of glioblastoma, molecular markers for TTF sensitivity have proven elusive. METHODS To assess impact of molecular alterations on TTF response, we evaluated our institutional cohort of IDH wild type glioblastomas (n=449) for whom chromosomal microarray data was available. RESULTS A total of 142 patients were found to have undergone TTF treatment (31.6%) with improved overall survival (OS) (p=0.0049, univariate analysis). We assessed TTF treatment responses when stratified by alterations in the MDM2/4-TP53 axis, as well as the CDK4/6-RB1 axis, given well-described roles for these pathways on cellular responses to DNA damage and mitotic stressors. On univariate analysis, MDM2/4 amplified tumors treated with TTFs demonstrated significantly improved OS compared to untreated tumors (p=0.0012), and while MDM2/4-unaltered, TP53 intact tumors showed OS benefit from TTFs (p=0.0192), TP53-altered tumors did not demonstrate such benefit (p=0.6591). We confirmed these findings with multivariate Cox regression after adjusting for age and sex, where TTF therapy improved OS in MDM2/4 amplified tumors (HR 0.3881, p=0.0062) and a signal towards improved OS was seen in TP53 intact tumors (HR 0.7552, p=0.0509) but no such benefit was seen in TP53-altered tumors (HR 1.0025, p=0.9916). TTF therapy appeared to demonstrate improved OS in CDK4/6 amplified tumors (p=0.0116) on univariate analysis, with continued signal towards this effect on multivariate Cox regression (HR 0.5975, p=0.0870). CONCLUSIONS TP53 intact status and MDM2/4 amplification may represent previously unappreciated molecular markers for sensitivity to TTF therapy in IDH wild type glioblastoma. Confirmatory work with multi-institutional collaborations and evaluation of other potential prognostic factors are currently underway.

Abstract BACKGROUND Chromosomal instability is a well-recognized hallmark of tumorigenesis. However, it is not known how markers for chromosomal instability, such as total distance of DNA altered or total copy number variations (CNV), affect survival, particularly in IDH wild type glioblastoma. Additionally, whether alterations in pathways that impact cellular responses to chromosomal instability, such as the TP53 or RB1 axis, influence survival, similarly remain poorly understood. METHODS To better characterize potential prognostic impact of markers of chromosomal instability on patient outcomes, we assessed the Mayo Clinic cohort of IDH wild type glioblastomas (n=449) for whom chromosomal microarray data was available. RESULTS We found that while total distance of DNA altered on microarray analysis was not associated with overall survival (OS) (p=0.4030, univariate analysis), the least altered tumors (stratified by quartiles) when assessed by numbers of CNVs demonstrated improved OS (p=0.0057, univariate analysis). We next evaluated alterations in the MDM2/4-TP53 signaling axis, as well as the CDKN2A/B-CDK4/6-RB1 axis, as both amplifications and losses impacting these pathways have been well characterized in adult diffuse gliomas. While TP53 status was not predictive of OS (p=0.1504, univariate analysis), amplification of MDM2 or MDM4 was predictive of decreased OS (p=0.0071, univariate analysis). We also found that tumors without alterations in the CDKN2A/B-CDK4/6-RB1 axis had improved OS when compared to altered tumors (p<0.0001, univariate analysis). Multivariate Cox regression analysis, adjusting for age and sex, confirmed prognostic impact of MDM2/4 amplification status (HR 1.4090, p=0.0370) and CNV status (HR 0.6798, p=0.00312) on OS. CONCLUSIONS CNV status and MDM2/4 amplification represent previously unappreciated molecular markers for prognostication in IDH wild type glioblastoma. Further work is underway to confirm our findings through multi-institutional collaborations and to account for additional potential prognostic factors.

Abstract Telomere length variation is a hallmark of genomic instability, however, its role in shaping the structural variant (SV) landscape of diffuse astrocytoma remains poorly understood. In this study, we employed Oxford Nanopore long-read sequencing to investigate the association between SVs and chromosome arm-specific telomere length in a clinical patient cohort consisting of n = 20 individuals diagnosed with an IDH mutant astrocytoma. Oxford Nanopore long-read sequencing was performed to a depth of ~20-40× coverage. SVs were identified using Sniffles, copy number alterations were assessed using DNAcopy and chromosome arm-specific telomere length was estimated with Telogator. Statistical analyses were conducted to assess associations between telomere dynamics, structural variation, and copy number changes. Astrocytoma genomes exhibited a broad spectrum of structural variants, including deletions and insertions, with significant enrichment in the short arms of acrocentric chromosomes. A subset of samples demonstrated markedly shorter telomeres relative to the overall cohort, accompanied by an increased burden of structural variants, particularly duplications and inversions, suggesting enhanced genomic instability. Notably, a prominent accumulation of deletion and insertion SVs was observed near chromosome ends and centromeres, highlighting the (sub)telomeric and peri(centromeric) regions as SV hotspots. Statistical modeling revealed a significant association between telomere length and arm-specific variation, including telomeric deletions, inversions, and copy number losses. In summary, our findings reveal a previously underappreciated link between SVs and telomere length in astrocytomas. Genomic rearrangements caused by telomere shortening may represent critical drivers of genome instability and could serve as novel biomarkers for disease progression.

Abstract Background Central nervous system (CNS) tumors are a significant cause of morbidity and mortality in sub-Saharan Africa (SSA). To date, no large-scale efforts have focused on brain tumor genetics within this region. This study aimed to assess and map the current neuro-oncology capacity in SSA, including workforce availability and existing services for brain tumor registries and biobanks. The results represent the final analysis representing respondents from 70 healthcare institutions. Methods This cross-sectional study utilized an online survey to collect data from healthcare professionals involved in CNS tumor care across SSA through the Society for Neuro-Oncology SSA (SNOSSA). The survey gathered information on the availability of neuro-oncology practitioners, neuropathology and molecular diagnostic capacity, brain tumor management, cancer registries, and biobanking of specimens. Purposive sampling was used to identify participants, with the questionnaire provided in English, French, and Swahili. Results A total of 145 respondents from 22 countries and 70 healthcare institutions participated. Among the 70 institutions, neurosurgery was available in 89%, anatomic pathology in 74%, and medical oncology in 71%. For radiologic evaluation, 64% of institutions reported having both CT and MRI, while 17% had CT only. Molecular testing through IHC or NGS was available in 46% of institutions. Multidisciplinary tumor boards for CNS cases were present in 86% of institutions. General cancer registries were available in 66% of institutions, while 29% had brain tumor-specific registries, and 10% maintained brain tumor biorepositories. Conclusion This study provides a comprehensive summary of the neuro-oncology capacity in SSA. Next steps are to reach out to institutions who have registries and determine what data are being collected, with the hopes of defining a set of common elements to expand registry efforts across SSA. Similarly, to reach out to institutions that have ongoing brain tumor biobanks and CT/MRI capacity to determine what infrastructure exists.

Importance Adverse events in otolaryngology–head and neck surgery (OHNS) are inconsistently reported. The Clavien-Dindo Classification has been modified and validated in several surgical subspecialties but has yet to be validated in OHNS. Objective To create and validate a modified Clavien-Dindo Classification for OHNS that reflects the severity and duration of harm for complications experienced by patients undergoing OHNS. Design, Setting, and Participants This is a multicenter survey study of subject matter experts (SMEs) from OHNS subspecialties from academic institutions within the US. A literature review identified publications reporting surgical complications in OHNS in the English language between January 2019 and April 2020. Complications were summarized and used to inform a modified Clavien-Dindo Classification. Feedback from internal SMEs was incorporated. Thirty-five clinical vignettes were created, and an electronic survey was sent to SMEs at outside institutions. Each SME was randomly assigned to 1 of 4 groups to evaluate 8 to 9 vignettes. The survey was conducted in September 2023, and data were analyzed from February to May 2024. Exposure Participation in the electronic survey. Main Outcomes and Measures Vignette scores were assessed and the Comprehensive Complication Index (CCI) calculator was used to assess cumulative morbidity. The scale is based on the grading by the Clavien-Dindo Classification and reflects overall morbidity on a scale from 0 (no complication) to 100 (death). Variability of the CCIs between reviewers, the primary outcome, was summarized with the SD. The percentage of reviewers with a high (≥26.2) or low (<26.2) CCI within a vignette was reported. Reliability was summarized using Krippendorff α. Results Of 106 SMEs, 43 (response rate, 40.6%) completed at least 1 vignette. Eighteen of 35 vignettes (51.4%; 95% CI, 34.9%-68.0%) had unanimous high CCI, and 8 of 35 vignettes (22.9%; 95% CI, 8.9%-36.8%) had unanimous low CCI (overall categorical agreement, 74.3%; 95% CI, 59.8%-88.8%). On average, the Krippendorff α was 0.74, indicating moderate reliability. A total of 21 850 OHNS complications were reviewed and categorized as surgical or medical with 12 including subcategorization for specificity. Each category was then assigned a modified OHNS Clavien Dindo classification grade. Conclusions and Relevance In this survey study of OHNS experts, a modified OHNS Clavien-Dindo Classification was developed and validated using case vignettes. The modified Clavien-Dindo Classification provided a granular subcategorization for each complication category and grade, duration of harm, and an overall summary complication score (CCI). Results suggest the modified OHNS Clavien-Dindo Classification reliably differentiated between high-grade and low-grade OHNS complications and could be utilized for assessing surgical outcomes.