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Background: Alzheimer’s disease neuropathologic change (ADNC) is defined by the progression of both hyperphosphorylated-tau (p-tau) and amyloid-β (Aβ) and is the most common underlying cause of dementia worldwide. Primary age-related tauopathy (PART), an Aβ-negative tauopathy largely confined to the medial temporal lobe, is increasingly being recognized as an entity separate from ADNC with diverging clinical, genetic, neuroanatomic, and radiologic profiles. Objective: The specific clinical correlates of PART are largely unknown; we aimed to identify cognitive and neuropsychological differences between PART, ADNC, and subjects with no tauopathy (NT). Methods: We compared 2,884 subjects with autopsy-confirmed intermediate-high stage ADNC to 208 subjects with definite PART (Braak stage I–IV, Thal phase 0, CERAD NP score “absent”) and 178 NT subjects from the National Alzheimer’s Coordinating Center dataset. Results: PART subjects were older than either ADNC or NT patients. The ADNC cohort had more frequent neuropathological comorbidities as well as APOE ɛ4 alleles than the PART or NT cohort, and less frequent APOE ɛ2 alleles than either group. Clinically, ADNC patients performed significantly worse than NT or PART subjects across cognitive measures, but PART subjects had selective deficits in measures of processing speed, executive function, and visuospatial function, although additional cognitive measures were further impaired in the presence of neuropathologic comorbidities. In isolated cases of PART with Braak stage III-IV, there are additional deficits in measures of language. Conclusion: Overall, these findings demonstrate underlying cognitive features specifically associated with PART, and reinforce the concept that PART is a distinct entity from ADNC.

Background: The strongest risk factor for the development of Alzheimer’s disease (AD) is age. The progression of Braak stage and Thal phase with age has been demonstrated. However, prior studies did not include cognitive status. Objective: We set out to define normative values for Alzheimer-type pathologic changes in individuals without cognitive decline, and then define levels that would qualify them to be resistant to or resilient against these changes. Methods: Utilizing neuropathology data obtained from the National Alzheimer’s Coordinating Center (NACC), we demonstrate the age-related progression of Alzheimer-type pathologic changes in cognitively normal individuals (CDR = 0, n = 542). With plots generated from these data, we establish standard lines that may be utilized to measure the extent to which an individual’s Alzheimer-type pathology varies from the estimated normal range of pathology. Results: Although Braak stage and Thal phase progressively increase with age in cognitively normal individuals, the Consortium to Establish a Registry for Alzheimer’s Disease neuritic plaque score and Alzheimer’s disease neuropathologic change remain at low levels. Conclusion: These findings suggest that an increasing burden of neuritic plaques is a strong predictor of cognitive decline, whereas, neurofibrillary degeneration and amyloid-β (diffuse) plaque deposition, both to some degree, are normal pathologic changes of aging that occur in almost all individuals regardless of cognitive status. Furthermore, we have defined the amount of neuropathologic change in cognitively normal individuals that would qualify them to be “resilient” against the pathology (significantly above the normative values for age, but still cognitively normal) or “resistant” to the development of pathology (significantly below the normative values for age).

Alzheimer disease (AD) is currently the leading cause of cognitive decline and dementia worldwide. Recently, studies have suggested that other neurodegenerative comorbidities such as limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC), Lewy body disease (LBD), and cerebrovascular disease frequently co-occur with Alzheimer disease neuropathologic change (ADNC) and may have significant cognitive effects both in isolation and synergistically with ADNC. Herein, we study the relative clinical impact of these multiple neurodegenerative pathologies in 704 subjects. Each of these pathologies is relatively common in the cognitively impaired population, while cerebrovascular pathology and ADNC are the most common in cognitively normal individuals. Moreover, while the number of concurrent neuropathologic entities rises with age and has a progressively deleterious effect on cognition, 44.3% of cognitively intact individuals are resistant to having any neurodegenerative proteinopathy (compared to 15.2% of cognitively impaired individuals) and 83.5% are resistant to having multiple concurrent proteinopathies (compared to 64.6% of cognitively impaired individuals). The presence of at least 1 APOE ε4 allele was associated with impaired cognition and the presence of multiple proteinopathies, while APOE ε2 was protective against cumulative proteinopathies. These results indicate that maintenance of normal cognition may depend on resistance to the development of multiple concurrent proteinopathies.

Chronic traumatic encephalopathy (CTE) is a tauopathy associated with repetitive mild head impacts characterized by perivascular hyperphosphorylated tau (p-tau) in neurofibrillary tangles (NFTs) and neurites in the depths of the neocortical sulci. In moderate to advanced CTE, NFTs accumulate in the hippocampus, potentially overlapping neuroanatomically with primary age-related tauopathy (PART), an age-related tauopathy characterized by Alzheimer disease-like tau pathology in the hippocampus devoid of amyloid plaques. We measured p-tau burden using positive-pixel counts on immunohistochemically stained and neuroanatomically segmented hippocampal tissue. Subjects with CTE had a higher total p-tau burden than PART subjects in all sectors (p = 0.005). Within groups, PART had significantly higher total p-tau burden in CA1/subiculum compared to CA3 (p = 0.02) and CA4 (p = 0.01) and total p-tau burden in CA2 trended higher than CA4 (p = 0.06). In CTE, total p-tau burden in CA1/subiculum was significantly higher than in the dentate gyrus; and CA2 also trended higher than dentate gyrus (p = 0.01, p = 0.06). When controlling for p-tau burden across the entire hippocampus, CA3 and CA4 had significantly higher p-tau burden in CTE than PART (p lt; 0.0001). These data demonstrate differences in hippocampal p-tau burden and regional distribution in CTE compared to PART that might be helpful in differential diagnosis and reveal insights into disease pathogenesis.

Purpose: Metabolism within the tumor microenvironment (TME) represents an increasing area of interest to understand glioma initiation and progression. Stable isotope tracing is a technique critical to the study of tumor metabolism. Cell culture models of this disease are not routinely cultured under physiologically relevant nutrient conditions and do not retain cellular heterogeneity present in the parental TME. Moreover, in vivo, stable isotope tracing in intracranial glioma xenografts, the gold standard for metabolic investigation, is time consuming and technically challenging. To provide insights into glioma metabolism in the presence of an intact TME, we performed stable isotope tracing analysis of patient-derived, heterocellular Surgically eXplanted Organoid (SXO) glioma models in human plasma-like medium (HPLM). Methods: Glioma SXOs were established and cultured in conventional media or transitioned to HPLM. We evaluated SXO cytoarchitecture and histology, then performed spatial transcriptomic profiling to identify cellular populations and differential gene expression patterns. We performed stable isotope tracing with15N2-glutamine to evaluate intracellular metabolite labeling patterns. Results: Glioma SXOs cultured in HPLM retain cytoarchitecture and cellular constituents. Immune cells in HPLM-cultured SXOs demonstrated increased transcription of immune-related signatures, including innate immune, adaptive immune, and cytokine signaling programs.15N isotope enrichment from glutamine was observed in metabolites from diverse pathways, and labeling patterns were stable over time. Conclusion: To enable ex vivo, tractable investigations of whole tumor metabolism, we developed an approach to conduct stable isotope tracing in glioma SXOs cultured under physiologically relevant nutrient conditions. Under these conditions, SXOs maintained viability, composition, and metabolic activity while exhibiting increased immune-related transcriptional programs.

Background IDH mutations are thought to represent an early oncogenic event in glioma evolution, found with high penetrance across tumor cells, however in rare cases IDH mutation may exist only in a small subset of the total tumor cells (subclonal IDH-mutation). Methods We present two institutional cases with subclonal IDH1 R132H mutation. In addition, two large publicly-available cohorts of IDH-mutant astrocytomas were mined for cases harboring subclonal IDH mutations (defined as tumor cell fraction (TCF) with IDH mutation ≤0.67) and the clinical and molecular features of these subclonal cases were compared to clonal IDH-mutant astrocytomas. Results Immunohistochemistry (IHC) performed on two institutional WHO grade 4 IDH-mutant astrocytomas revealed only a minority of tumor cells in each case with IDH1 R132H mutant protein, and next-generation sequencing (NGS) revealed remarkably low IDH1 variant allele frequencies compared to other pathogenic mutations, including TP53 and/or ATRX. DNA methylation classified the first tumor as high-grade IDH-mutant astrocytoma with high confidence (0.98 score). In the publicly-available datasets, subclonal IDH mutation was present in 3.9% of IDH-mutant astrocytomas (18/466 tumors). Compared to clonal IDH-mutant astrocytomas (n=156), subclonal cases demonstrated worse overall survival in grades 3 (p=0.0106) and 4 (p=0.0184). Conclusions While rare, subclonal IDH1 mutations are present in a subset of IDH-mutant astrocytomas of all grades, which may lead to a mismatch between IHC results and genetic/epigenetic classification. These findings suggest a possible prognostic role of IDH mutation subclonality, and highlight the potential clinical utility of quantitative IDH1 mutation evaluation by IHC and NGS.

Background Tumor invasion, a hallmark of malignant gliomas, involves reorganization of cell polarity and changes in the expression and distribution of scaffolding proteins associated with polarity complexes. The scaffolding proteins of the DLG family are usually downregulated in invasive tumors and regarded as tumor suppressors. Despite their important role in regulating neurodevelopmental signaling, the expression and functions of DLG proteins have remained almost entirely unexplored in malignant gliomas. Methods Western blot, immunohistochemistry, and analysis of gene expression were used to quantify DLG members in glioma specimens and cancer datasets. Over-expression and knockdown of DLG5, the highest-expressed DLG member in glioblastoma, were used to investigate its effects on tumor stem cells and tumor growth. qRT-PCR, Western blotting, and co-precipitation assays were used to investigate DLG5 signaling mechanisms. Results DLG5 was upregulated in malignant gliomas compared to other solid tumors, being the predominant DLG member in all glioblastoma molecular subtypes. DLG5 promoted glioblastoma stem cell invasion, viability, and self-renewal. Knockdown of this protein in vivo disrupted tumor formation and extended survival. At the molecular level, DLG5 regulated Sonic Hedgehog (Shh) signaling, making DLG5-deficient cells insensitive to Shh ligand. Loss of DLG5 increased the proteasomal degradation of Gli1, underlying the loss of Shh signaling and tumor stem cell sensitization. Conclusions The high expression and pro-tumoral functions of DLG5 in glioblastoma, including its dominant regulation of Shh signaling in tumor stem cells, reveal a novel role for this protein that is strikingly different from its proposed tumor-suppressor role in other solid tumors.

Background Historically, creating patient-derived models of lower-grade glioma (LGG) has been challenging, contributing to few experimental platforms that support laboratory-based investigations of this disease. Although organoid modeling approaches have recently been employed to create in vitro models of high-grade glioma (HGG), it is unknown whether this approach can be successfully applied to LGG. Methods In this study, we developed an optimized protocol for the establishment of organoids from LGG primary tissue samples by utilizing physiologic (5%) oxygenation conditions and employed it to produce the first known suite of these models. To assess their fidelity, we surveyed key biological features of patient-derived organoids using metabolic, genomic, histologic, and lineage marker gene expression assays. Results Organoid models were created with a success rate of 91% (n = 20/22) from primary tumor samples across glioma histological subtypes and tumor grades (WHO Grades 1–4), and a success rate of 87% (13/15) for WHO Grade 1–3 tumors. Patient-derived organoids recapitulated stemness, proliferative, and tumor-stromal composition profiles of their respective parental tumor specimens. Cytoarchitectural, mutational, and metabolic traits of parental tumors were also conserved. Importantly, LGG organoids were maintained in vitro for weeks to months and reanimated after biobanking without loss of integrity. Conclusions We report an efficient method for producing faithful in vitro models of LGG. New experimental platforms generated through this approach are well positioned to support preclinical studies of this disease, particularly those related to tumor immunology, tumor-stroma interactions, identification of novel drug targets, and personalized assessments of treatment response profiles.

Primary age-related tauopathy (PART) is a neurodegenerative pathology with features distinct from but also overlapping with Alzheimer disease (AD). While both exhibit Alzheimer-type temporal lobe neurofibrillary degeneration alongside amnestic cognitive impairment, PART develops independently of amyloid-β (Aβ) plaques. The pathogenesis of PART is not known, but evidence suggests an association with genes that promote tau pathology and others that protect from Aβ toxicity. Here, we performed a genetic association study in an autopsy cohort of individuals with PART (n = 647) using Braak neurofibrillary tangle stage as a quantitative trait. We found some significant associations with candidate loci associated with AD (SLC24A4, MS4A6A, HS3ST1) and progressive supranuclear palsy (MAPT and EIF2AK3). Genome-wide association analysis revealed a novel significant association with a single nucleotide polymorphism on chromosome 4 (rs56405341) in a locus containing three genes, including JADE1 which was significantly upregulated in tangle-bearing neurons by single-soma RNA-seq. Immunohistochemical studies using antisera targeting JADE1 protein revealed localization within tau aggregates in autopsy brains with four microtubule-binding domain repeats (4R) isoforms and mixed 3R/4R, but not with 3R exclusively. Co-immunoprecipitation in post-mortem human PART brain tissue revealed a specific binding of JADE1 protein to four repeat tau lacking N-terminal inserts (0N4R). Finally, knockdown of the Drosophila JADE1 homolog rhinoceros (rno) enhanced tau-induced toxicity and apoptosis in vivo in a humanized 0N4R mutant tau knock-in model, as quantified by rough eye phenotype and terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) in the fly brain. Together, these findings indicate that PART has a genetic architecture that partially overlaps with AD and other tauopathies and suggests a novel role for JADE1 as a modifier of neurofibrillary degeneration.

Numerous recent studies have demonstrated that the vast majority of IDH-wildtype astrocytomas with WHO grade II/III histology have clinical outcomes equivalent to IDH-wildtype glioblastomas. This has called into question the existence of an IDH-wildtype lower-grade astrocytoma (LGA) category, and the cIMPACT-NOW study group has suggested 3 molecular features which, if present, warrant upgrading IDH-wildtype LGA to glioblastoma: EGFR amplification, 7+/10-, and TERT promoter mutation. Herein, we evaluate the clinical, histologic, and molecular features of IDH-wildtype low-grade astrocytomas, defined here as infiltrative adult astrocytoma lacking histologic features of glioblastoma (microvascular proliferation and/or necrosis), IDH1/2 mutation, and all 3 of the cIMPACT-NOW update 3 factors. Compared with their counterparts with cIMPACT-NOW features of glioblastoma (LGA-C+; n = 108), IDH-wildtype LGAs lacking these features (LGA-C0; n = 36) occur in significantly younger patients, are more frequently WHO grade II, have less total copy number variation distributed across the entire genome, less frequent homozygous deletion of CDKN2A, less frequent PTEN and PIK3CA alterations, and more frequent NF1 alterations. These results suggest that although rare, a "true" IDH-wildtype LGA category does exist, and has distinct clinical and molecular features consistent with relatively beneficial clinical outcomes in these patients.

Background Myxopapillary ependymoma (MPE) is a heterogeneous disease regarding histopathology and outcome. The underlying molecular biology is poorly understood, and markers that reliably predict the patients’ clinical course are unknown. Methods We assembled a cohort of 185 tumors classified as MPE based on DNA methylation. Methylation patterns, copy number profiles, and MGMT promoter methylation were analyzed for all tumors, 106 tumors were evaluated histomorphologically, and RNA sequencing was performed for 37 cases. Based on methylation profiling, we defined two subtypes MPE-A and MPE-B, and explored associations with epidemiological, clinical, pathological, and molecular characteristics of these tumors. Results MPE-A occurred at a median age of 27 years and were enriched with tumors demonstrating papillary morphology and MGMT promoter hypermethylation. Half of these tumors could not be totally resected, and 85% relapsed within 10 years. Copy number alterations were more common in MPE-A. RNA sequencing revealed an enrichment for extracellular matrix and immune system-related signatures in MPE-A. MPE-B occurred at a median age of 45 years and included many tumors with a histological diagnosis of WHO grade II and tanycytic morphology. Patients within this subtype had a significantly better outcome with a relapse rate of 33% in 10 years (P = 3.4e-06). Conclusions We unraveled the morphological and clinical heterogeneity of MPE by identifying two molecularly distinct subtypes. These subtypes significantly differed in progression-free survival and will likely need different protocols for surveillance and treatment.

Clinical symptoms correlate with underlying neurodegenerative changes in the vast majority of people. However, an intriguing group of individuals demonstrate neuropathologic changes consistent with Alzheimer disease (AD) yet remain cognitively normal (termed “resilient”). Previous studies have reported less overall neuronal loss, less gliosis, and fewer comorbidities in these individuals. Herein, NanoString GeoMx™ Digital Spatial Profiler (DSP) technology was utilized to investigate protein expression differences comparing individuals with dementia and AD neuropathologic change to resilient individuals. DSP allows for spatial analysis of protein expression in multiple regions of interest (ROIs) on formalin-fixed paraffin-embedded sections. ROIs in this analysis were hippocampal neurofibrillary tangle (NFT)-bearing neurons, non-NFT-bearing neurons, and their immediate neuronal microenvironments. Analyses of 86 proteins associated with CNS cell-typing or known neurodegenerative changes in 168 ROIs from 14 individuals identified 11 proteins displaying differential expression in NFT-bearing neurons of the resilient when compared to the demented (including APP, IDH1, CD68, GFAP, SYP and Histone H3). In addition, IDH1, CD68, and SYP were differentially expressed in the environment of NFT-bearing neurons when comparing resilient to demented. IDH1 (which is upregulated under energetic and oxidative stress) and PINK1 (which is upregulated in response to mitochondrial dysfunction and oxidative stress) both displayed lower expression in the environment of NFT-bearing neurons in the resilient. Therefore, the resilient display less evidence of energetic and oxidative stress. Synaptophysin (SYP) was increased in the resilient, which likely indicates better maintenance of synapses and synaptic connections. Furthermore, neurofilament light chain (NEFL) and ubiquitin c-terminal hydrolase (Park5) were higher in the resilient in the environment of NFTs. These differences all suggest healthier intact axons, dendrites and synapses in the resilient. In conclusion, resilient individuals display protein expression patterns suggestive of an environment containing less energetic and oxidative stress, which in turn results in maintenance of neurons and their synaptic connections.

A primitive neuronal component is a feature of some glioblastomas but defining molecular alterations of this histologic variant remains uncertain. We performed next-generation sequencing of 1500 tumor related genes on tissue from 9 patients with glioblastoma with a primitive component (G/PN) and analyzed 27 similar cases from the Cancer Genome Atlas (TCGA) dataset. Alterations in the RB pathway were identified in all of our patients’ tumors and 81% of TCGA tumors with the retinoblastoma tumor suppressor gene (RB1) commonly affected. Although RB1 mutations were observed in some conventional glioblastomas, the allelic fractions of these mutations were significantly higher in tumors with a primitive neuronal component in both our and TCGA cohorts (median, 72% vs 25%, p

SUMMARYMutations affecting isocitrate dehydrogenase (IDH) enzymes are prevalent in glioma, leukemia, and other cancers. Although mutant IDH inhibitors are effective against leukemia, they appear less active in aggressive glioma, underscoring the need for alternative treatment strategies. Through a chemical synthetic lethality screen, we discovered that IDH1 mutant glioma cells are hypersensitive to drugs targeting enzymes in the de novo pyrimidine nucleotide synthesis pathway, including dihydroorotate dehydrogenase (DHODH). We developed a genetically engineered mouse model of mutant IDH1-driven astrocytoma and used it and multiple patient-derived models to show that the brain-penetrant DHODH inhibitor BAY 2402234 displays monotherapy efficacy against IDH mutant gliomas. Mechanistically, this vulnerability selectively applies to de novo pyrimidine, but not purine, synthesis because glioma cells engage disparate programs to produce these nucleotide species and because IDH oncogenes increase DNA damage upon nucleotide pool imbalance. Our work outlines a tumor-selective, biomarker-guided therapeutic strategy that is poised for clinical translation.

The creation of patient-derived cancer organoids represents a key advance in preclinical modeling and has recently been applied to a variety of human solid tumor types. However, conventional methods used to assess cellular viability in tissue specimens are poorly suited for the evaluation of cancer organoids because they are time-intensive and involve tissue destruction. To address this issue, we established a suite of 3-dimensional patient-derived glioma organoids, treated them with chemoradiotherapy, stained organoids with non-toxic cell dyes, and imaged them using a rapid laser scanning confocal microscopy method termed “Apex Imaging”. We then developed and tested a fragmentation algorithm to quantify heterogeneity in the topography of the organoids as a potential surrogate marker of viability. This algorithm, SSDquant, provides a 3-dimensional visual representation of the organoid surface and a numerical measurement of the sum-squared distance (SSD) from the derived mass center of the organoid. We tested whether SSD scores correlate with traditional immunohistochemistry-derived cell viability markers (cellularity and cleaved caspase 3 expression) and observed statistically significant associations between them using linear regression analysis. Our work describes a quantitative, non-invasive approach for the serial measurement of patient-derived cancer organoid viability, thus opening new avenues for the application of these models to studies of cancer biology and therapy.

A wide variety of benign and malignant tumors can arise from different structures in the orbital and peri-orbital area, affecting the eye and the optic nerve. This spectrum of tumors includes primary and metastatic carcinomas, lymphomas, melanomas, soft tissue tumors, and primary tumors of the retina, optic disc, and optic nerve. These also extend to relatively rare entities such as solitary fibrous tumor and meningioma of the orbit and optic nerve, which can present with very similar clinical and radiologic features, although the tumor grades, treatment plans, and outcomes can vary widely. In this report, we present two clinical cases of solitary fibrous tumor [central nervous system (CNS) World Health Organization (WHO) grade 2 and 3) and compare their clinical presentation, radiologic and histologic features, treatment, and clinical outcomes to a group of three orbital meningiomas (CNS WHO grade 1 and 2). In the context of these five cases of orbital lesions, we review the current clinical, pathologic, and radiologic literature on orbital tumors, focusing primarily on solitary fibrous tumors and meningiomas, along with an expanded discussion on the diagnostic criteria of both entities, as well as the treatment and prognosis of these lesions.

Mutations affecting isocitrate dehydrogenase (IDH) enzymes are prevalent in glioma, leukemia, and other cancers. Although mutant IDH inhibitors are effective against leukemia, they seem to be less active in aggressive glioma, underscoring the need for alternative treatment strategies. Through a chemical synthetic lethality screen, we discovered that IDH1-mutant glioma cells are hypersensitive to drugs targeting enzymes in the de novo pyrimidine nucleotide synthesis pathway, including dihydroorotate dehydrogenase (DHODH). We developed a genetically engineered mouse model of mutant IDH1-driven astrocytoma and used it and multiple patient-derived models to show that the brain-penetrant DHODH inhibitor BAY 2402234 displays monotherapy efficacy against IDH-mutant gliomas. Mechanistically, this reflects an obligate dependence of glioma cells on the de novo pyrimidine synthesis pathway and mutant IDH's ability to sensitize to DNA damage upon nucleotide pool imbalance. Our work outlines a tumor-selective, biomarker-guided therapeutic strategy that is poised for clinical translation.

IntroductionThe portfolio of novel targets to treat Alzheimer’s disease (AD) has been enriched by the AMP-AD program.MethodsA cheminformatics-driven effort enabled identification of existing small molecule modulators for many protein targets nominated by AMP-AD and suitable positive control compounds to be included in the set.ResultsWe have built an annotated set of 171 small molecule modulators, including mostly inhibitors, targeting 98 unique proteins that have been nominated by AMP-AD consortium members as novel targets for AD treatment. These small molecules vary in their quality and should be considered chemical tools that can be used in efforts to validate therapeutic hypotheses, but which would require further optimization. A physical copy of the AD Informer Set can be ordered via the AD Knowledge Portal.DiscussionSmall molecule tools that enable target validation are important tools for the translation of novel hypotheses into viable therapeutic strategies for AD.

Primary age-related tauopathy (PART) is a form of Alzheimer-type neurofibrillary degeneration occurring in the absence of amyloid-beta (Aβ) plaques. While PART shares some features with Alzheimer disease (AD), such as progressive accumulation of neurofibrillary tangle pathology in the medial temporal lobe and other brain regions, it does not progress extensively to neocortical regions. Given this restricted pathoanatomical pattern and variable symptomatology, there is a need to reexamine and improve upon how PART is neuropathologically assessed and staged. We performed a retrospective autopsy study in a collection (n=174) of post-mortem PART brains and used logistic regression to determine the extent to which a set of clinical and neuropathological features predict cognitive impairment. We compared Braak staging, which focuses on hierarchical neuroanatomical progression of AD tau and Aβ pathology, with quantitative assessments of neurofibrillary burden using computer-derived positive pixel counts on digitized whole slide images of sections stained immunohistochemically with antibodies targeting abnormal hyperphosphorylated tau (p-tau) in the entorhinal region and hippocampus. We also assessed other factors affecting cognition, including aging-related tau astrogliopathy (ARTAG) and atrophy. We found no association between Braak stage and cognitive impairment when controlling for age (p=0.76). In contrast, p-tau burden was significantly correlated with cognitive impairment even when adjusting for age (p=0.03). The strongest correlate of cognitive impairment was cerebrovascular disease, a well-known risk factor (pp=0.03) and hippocampal atrophy (p=0.04) were also associated. In contrast, sex, APOE, psychiatric illness, education, argyrophilic grains, and incidental Lewy bodies were not. These findings support the hypothesis that comorbid pathologies contribute to cognitive impairment in subjects with PART. Quantitative approaches beyond Braak staging are critical for advancing our understanding of the extent to which age-related tauopathy changes impact cognitive function.

We present an unusual case of a 60-year-old female who developed subtle, new-onset left upper and lower extremity weakness on day five of perioperative thoracic epidural placement. The onset of a focal neurological deficit after epidural placement usually raises suspicion for the presence of an epidural hematoma, abscess, or traumatic cord lesion. However, in this patient, brain imaging revealed a large, previously undiagnosed intracranial mass. Classically, the risk of mass-related intracranial pressure shifts leading to neurological changes is associated with spinal techniques, including diagnostic lumbar puncture, combined spinal-epidural catheter analgesia, and unintended dural puncture during epidural placement. However, based on this case and our summary of case reports in the literature, we determined that symptom onset associated with an intracranial mass may also arise after apparently uncomplicated epidural placement. Symptom onset in our case series ranged from six hours to ten days and was highly variable depending on tumor location, with reported signs and symptoms including headache, vision changes, focal deficits, or alterations of consciousness. Further studies are required to establish definitive causation between the epidural technique and changes in cerebrospinal fluid pressures leading to symptom onset. Though rare, this is a time-sensitive diagnosis that must be considered for any patient with unexplained neurological findings after neuraxial anesthesia.

ROS1 is a transmembrane receptor tyrosine kinase proto-oncogene that has been shown to have rearrangements with several genes in glioblastoma and other neoplasms, including intrachromosomal fusion with GOPC due to microdeletions at 6q22.1. ROS1 fusion events are important findings in these tumors, as they are potentially targetable alterations with newer tyrosine kinase inhibitors; however, whether these tumors represent a distinct entity remains unknown. In this report, we identify 3 cases of unusual pediatric glioma with GOPC-ROS1 fusion. We reviewed the clinical history, radiologic and histologic features, performed methylation analysis, whole genome copy number profiling, and next generation sequencing analysis for the detection of oncogenic mutation and fusion events to fully characterize the genetic and epigenetic alterations present in these tumors. Two of 3 tumors showed pilocytic features with focal expression of synaptophysin staining and variable high-grade histologic features; the third tumor aligned best with glioblastoma and showed no evidence of neuronal differentiation. Copy number profiling revealed chromosome 6q22 microdeletions corresponding to the GOPC-ROS1 fusion in all 3 cases and methylation profiling showed that the tumors did not cluster together as a single entity or within known methylation classes by t-Distributed Stochastic Neighbor Embedding.

Since the discovery that IDH1/2 mutations confer a significantly better prognosis in astrocytomas, much work has been done to identify other molecular signatures to help further stratify lower-grade astrocytomas and glioblastomas, with the goal of accurately predicting clinical outcome and identifying potentially targetable mutations. In the present study, we subclassify 135 astrocytomas (67 IDH-wildtype and 68 IDH-mutant) from The Cancer Genome Atlas dataset (TCGA) on the basis of grade, IDH-status, and the previously established prognostic factors, CDK4 amplification and CDKN2A/B deletion, within the IDH-mutant groups. We analyzed these groups for total copy number variation (CNV), total mutation burden, chromothripsis, specific mutations, and amplifications/deletions of specific genes/chromosomal regions. Herein, we demonstrate that across all of these tumor groups, total CNV level is a relatively consistent prognostic factor. We also identified a trend towards increased levels of chromothripsis in tumors with lower progression-free survival (PFS) and overall survival (OS) intervals. While no significant differences were identified in overall mutation load, we did identify a significantly higher number of cases with mutations in genes with functions related to maintaining genomic stability in groups with higher mean CNV and worse PFS and OS intervals, particularly in the IDH-mutant groups. Our data further support the case for total CNV level as a potential prognostic factor in astrocytomas, and suggest mutations in genes responsible for overall genomic instability as a possible underlying mechanism for some astrocytomas with poor clinical outcome. Electronic supplementary material The online version of this article (10.1186/s40478-019-0746-y) contains supplementary material, which is available to authorized users.

Proteins complexes that maintain the apico-basal polarity of epithelial cells and organize cell-signaling domains are necessary for normal tissue organization and therefore regarded as tumor suppressors. Accordingly, the scaffolding proteins that form the Scribble polarity complex (SCRIB, LLGL1, and DLG members) are usually downregulated in cancer, in particular in highly aggressive or invasive tumors. Because gliomas arise from non-epithelial precursors that are likely motile before transformation, the expression and functions of these scaffolding proteins in malignant brain tumors has remained almost entirely unexplored. Surprisingly, we have found that one member of the DLG family, DLG5, is highly upregulated in malignant gliomas compared to other solid tumors. Indeed, DLG5 was the predominant DLG member found in all molecular subtypes of glioblastoma (GBM). Knockdown of DLG5 reduced the viability, invasiveness, and self-renewal of GBM stem cells belonging to the proneural and mesenchymal molecular subtypes. As a result, intracranial tumors defficient in DLG5 were smaller and less proliferative than controls, resulting in extended animal survival. At the molecular level, DLG5 knockdown decreased the expression of stemness-related genes (SOX2, NANOG, POU5F1) but increased the expression of LLGL1, a component of the Scribble complex that is associated with neural precursor differentiation. These changes were accompanied by downregulation of Sonic Hedgehog (SHh) signaling, both in vitro and in vivo, which drives GBM cell stemness and proliferation. Moreover, DLG5-deficient GBM stem cells became insensitive to exogenous SHh and were unable to upregulate Gli1 or increase cell invasion in presence of added SHh, compared to control cells. We further confirmed that DLG5 downregulation increased the ubiquitination of Gli1-containing complexes as well as Gli1 proteasomal degradation, providing a suitable mechanism for the loss of SHh signaling and tumor stemness. These results describe for the first time the expression of a DLG family member in malignant gliomas and reveal a novel, polarity-independent, pro-tumoral function of DLG5, which differs from its proposed tumor-suppressor role in other solid tumors. Citation Format: Somanath Kundu, Mohan S. Nandhu, Sharon L. Longo, John A. Longo, Shawn Rai, Lawrence S. Chin, Timothy E. Richardson, Mariano S. Viapiano. The scaffolding protein DLG5 is necessary to maintain Sonic Hedgehog signaling in glioblastoma stem cells and promote tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3167.

Glioblastoma (GBM) is the most common malignant primary central nervous system (CNS) neoplasm in adults, and has an almost universally poor prognosis. Recently, an emphasis on genetic and epigenetic profiling has revealed a number of molecular features useful in the diagnostic and prognostic classification of GBM, advancing our understanding of the underlying features that make these tumors so aggressive and providing the rationale for the creation of better targeted therapeutics. One such method, DNA methylation profiling, has recently emerged as an important technique for the classification of CNS tumors, with diagnostic accuracy in some cases surpassing traditional methods. However, how DNA methylation profiles change with the course of the disease remains less understood. Here, we present a case of a 30-year-old male with primary IDH-mutant GBM with widespread recurrence and death two years later. Using unsupervised hierarchical clustering of methylation probes, we created a phylogenetic map to trace the tumor path as it spread from the initial biopsy site throughout the right hemisphere, across the corpus callosum to the contralateral hemisphere, and into the brainstem. We identified molecular divergence between the right and left hemisphere GBM samples marked by distinct copy number profile alterations, alterations in specific methylation sites, and regional loss of MGMT promoter methylation, providing a potential mechanism for treatment resistance in this case. In summary, this case both highlights the molecular diversity in GBM, and illustrates a novel use for methylation profiling in establishing a phylogenetic profile to allow for spatial mapping of tumor progression. Supplementary Information The online version contains supplementary material available at 10.1186/s40478-021-01221-7.

Primary age-related tauopathy (PART) is a neurodegenerative entity defined as neurofibrillary degeneration generally restricted to the medial temporal region (Braak stage I-IV) with complete or near absence of diffuse and neuritic plaques. Symptoms range in severity but are generally milder and later in onset than in Alzheimer disease (AD). Recently, an early predilection for neurofibrillary degeneration in the hippocampal CA2 subregion has been demonstrated in PART, whereas AD neuropathologic change (ADNC) typically displays relative sparing of CA2 until later stages. In this study, we utilized a semiquantitative scoring system to evaluate asymmetry of neurofibrillary degeneration between left and right hippocampi in 67 PART cases and 17 ADNC cases. 49% of PART cases demonstrated asymmetric findings in at least one hippocampal subregion, and 79% of the asymmetric cases displayed some degree of CA2 asymmetry. Additionally, 19% of cases revealed a difference in Braak score between the right and left hippocampi. There was a significant difference in CA2 neurofibrillary degeneration (p = 0.0006) and CA2/CA1 ratio (p < 0.0001) when comparing the contralateral sides, but neither right nor left was more consistently affected. These data show the importance of analyzing bilateral hippocampi in the diagnostic evaluation of PART and potentially of other neurodegenerative diseases.

Chromosomal instability due to mutations in genes guarding the stability of the genome is a well-known mechanism underlying tumorigenesis and malignant progression in numerous cancers. The effect of this process in gliomas is mostly unknown with relatively little research examining the effects of chromosomal instability on patient outcome and therapeutic efficacy, although studies have shown that overall/total copy number variation (CNV) is elevated in higher histologic grades and in cases with more rapid progression and shorter patient survival. Herein, we examine a 70-gene mRNA expression signature (CIN70), which has been previously shown to correlate tightly with chromosomal instability, in 2 independent cohorts of IDH-mutant astrocytomas (total n = 241), IDH-wildtype astrocytomas (n = 228), and oligodendrogliomas (n = 128). Our results show that CIN70 expression levels correlate with total CNV, as well as higher grade, progression-free survival, and overall survival in both IDH-mutant and IDH-wildtype astrocytomas. In oligodendrogliomas, these mRNA signatures correlate with total CNV but not consistently with clinical outcome. These data suggest that chromosomal instability is an underlying factor in aggressive behavior and progression of a subset of diffuse astrocytomas. In addition, chromosomal instability may in part explain the poor response of diffuse gliomas to treatment and may serve as a future therapeutic target.

The emergence of three-dimensional human organoids has opened the door for the development of patient-derived cancer organoid (PDO) models, which closely recapitulate parental tumor tissue. The mainstays of preclinical cancer modeling include in vitro cell lines and patient-derived xenografts, but these models lack the cellular heterogeneity seen in human tumors. Moreover, xenograft establishment is resource and time intensive, rendering these models difficult to use to inform clinical trials and decisions. PDOs, however, can be created efficiently and retain tumor-specific properties such as cellular heterogeneity, cell–cell and cell–stroma interactions, the tumor microenvironment, and therapeutic responsiveness. PDO models and drug-screening protocols have been described for several solid tumors and, more recently, for gliomas. Since PDOs can be developed in clinically relevant time frames and share many characteristics of parent tumors, they may enhance the ability to provide precision oncologic care for patients. This review explores the current literature on cancer organoids, highlighting the history of PDO development, organoid models of glioma, and potential clinical applications of PDOs.