Haploinsufficiency of phosphodiesterase 10A activates PI3K/AKT signaling independent of PTEN to induce an aggressive glioma phenotype.

Glioblastoma is universally fatal and characterized by frequent chromosomal copy number alterations harboring oncogenes and tumor suppressors. In this study, we analyzed exome-wide human glioblastoma copy number data and found that cytoband 6q27 is an independent poor prognostic marker in multiple data sets. We then combined CRISPR-Cas9 data, human spatial transcriptomic data, and human and mouse RNA sequencing data to nominate PDE10A as a potential haploinsufficient tumor suppressor in the 6q27 region. Mouse glioblastoma modeling using the RCAS/tv-a system confirmed that Pde10a suppression induced an aggressive glioma phenotype in vivo and resistance to temozolomide and radiation therapy in vitro. Cell culture analysis showed that decreased Pde10a expression led to increased PI3K/AKT signaling in a Pten-independent manner, a response blocked by selective PI3K inhibitors. Single-nucleus RNA sequencing from our mouse gliomas in vivo, in combination with cell culture validation, further showed that Pde10a suppression was associated with a proneural-to-mesenchymal transition that exhibited increased cell adhesion and decreased cell migration. Our results indicate that glioblastoma patients harboring PDE10A loss have worse outcomes and potentially increased sensitivity to PI3K inhibition.

Both YAP1-MAML2 and constitutively active YAP1 drive the formation of tumors that resemble NF2 mutant meningiomas in mice.

YAP1 is a transcriptional coactivator regulated by the Hippo signaling pathway, including NF2. Meningiomas are the most common primary brain tumors; a large percentage exhibit heterozygous loss of chromosome 22 (harboring the NF2 gene) and functional inactivation of the remaining NF2 copy, implicating oncogenic YAP activity in these tumors. Recently, fusions between YAP1 and MAML2 have been identified in a subset of pediatric NF2 wild-type meningiomas. Here, we show that human YAP1-MAML2-positive meningiomas resemble NF2 mutant meningiomas by global and YAP-related gene expression signatures. We then show that expression of YAP1-MAML2 in mice induces tumors that resemble human YAP1 fusion-positive and NF2 mutant meningiomas by gene expression. We demonstrate that YAP1-MAML2 primarily functions by exerting TEAD-dependent YAP activity that is resistant to Hippo signaling. Treatment with YAP-TEAD inhibitors is sufficient to inhibit the viability of YAP1-MAML2-driven mouse tumors ex vivo. Finally, we show that expression of constitutively active YAP1 (S127/397A-YAP1) is sufficient to induce similar tumors, suggesting that the YAP component of the gene fusion is the critical driver of these tumors. In summary, our results implicate YAP1-MAML2 as a causal oncogenic driver and highlight TEAD-dependent YAP activity as an oncogenic driver in YAP1-MAML2 fusion meningioma as well as NF2 mutant meningioma in general.

Comparison of tumor-associated YAP1 fusions identifies a recurrent set of functions critical for oncogenesis.

YAP1 is a transcriptional coactivator and the principal effector of the Hippo signaling pathway, which is causally implicated in human cancer. Several YAP1 gene fusions have been identified in various human cancers and identifying the essential components of this family of gene fusions has significant therapeutic value. Here, we show that the YAP1 gene fusions YAP1-MAMLD1, YAP1-FAM118B, YAP1-TFE3, and YAP1-SS18 are oncogenic in mice. Using reporter assays, RNA-seq, ChIP-seq, and loss-of-function mutations, we can show that all of these YAP1 fusion proteins exert TEAD-dependent YAP activity, while some also exert activity of the C'-terminal fusion partner. The YAP activity of the different YAP1 fusions is resistant to negative Hippo pathway regulation due to constitutive nuclear localization and resistance to degradation of the YAP1 fusion proteins. Genetic disruption of the TEAD-binding domain of these oncogenic YAP1 fusions is sufficient to inhibit tumor formation in vivo, while pharmacological inhibition of the YAP1-TEAD interaction inhibits the growth of YAP1 fusion-expressing cell lines in vitro. These results highlight TEAD-dependent YAP activity found in these gene fusions as critical for oncogenesis and implicate these YAP functions as potential therapeutic targets in YAP1 fusion-positive tumors.

Increased HOXA5 expression provides a selective advantage for gain of whole chromosome 7 in IDH wild-type glioblastoma.

Glioblastoma is the most frequently occurring and invariably fatal primary brain tumor in adults. The vast majority of glioblastomas is characterized by chromosomal copy number alterations, including gain of whole chromosome 7 and loss of whole chromosome 10. Gain of whole chromosome 7 is an early event in gliomagenesis that occurs in proneural-like precursor cells, which give rise to all isocitrate dehydrogenase (IDH) wild-type glioblastoma transcriptional subtypes. Platelet-derived growth factor A (PDGFA) is one gene on chromosome 7 known to drive gliomagenesis, but, given its location near the end of 7p, there are likely several other genes located along chromosome 7 that select for its increased whole-chromosome copy number within glioblastoma cells. To identify other potential genes that could select for gain of whole chromosome 7, we developed an unbiased bioinformatics approach that identified homeobox A5 (HOXA5) as a gene whose expression correlated with gain of chromosome 7 and a more aggressive phenotype of the resulting glioma. High expression of HOXA5 in glioblastoma was associated with a proneural gene expression pattern and decreased overall survival in both human proneural and PDGF-driven mouse glioblastoma. Furthermore, HOXA5 overexpression promoted cellular proliferation and potentiated radioresistance. We also found enrichment of HOXA5 expression in recurrent human and mouse glioblastoma at first recurrence after radiotherapy. Overall, this study implicates HOXA5 as a chromosome 7-associated gene-level locus that promotes selection for gain of whole chromosome 7 and an aggressive phenotype in glioblastoma.

Diffuse Pediatric-type High-grade Glioma Arising in an Ovarian Mature Cystic Teratoma.

Immature neuroectodermal tissue can be found in the ovary as part of an immature teratoma or as part of a teratoma with malignant neuroectodermal transformation. Such lesions may closely resemble central nervous system tumors, but their biologic similarity is unclear. We describe an 18-yr-old female who presented with abdominal pain caused by an ovarian mass with widespread metastases. Histology showed a primitive, high-grade tumor arising in the background of a mature teratoma. The tumor was SOX10 positive, with focal expression of GFAP, S100, NSE, and synaptophysin. Molecular analysis demonstrated co-amplification of PDGFRA and KIT , alterations common in high-grade gliomas. By whole-genome methylation profiling, it clustered into the "diffuse pediatric-type high-grade glioma, RTK1 subtype, subclass c" group. Despite progressing through 2 lines of chemotherapy with widespread metastatic disease, she achieved an excellent response to chemotherapy directed toward aggressive germ cell tumors. This case emphasizes the importance of immunohistochemical, genomic, and epigenetic analyses to accurately classify these exceedingly rare tumors and determine the optimal therapy.

When a dermatopathologist encounters the ultra-rare: A case series of superficial soft tissue/cutaneous myxopapillary ependymomas.

Myxopapillary ependymoma (MPE) is an uncommon variant of ependymoma, almost exclusively seen in conus medullaris or filum terminale. MPE can be diagnostically challenging, especially when arising extra-axially. Here we report 5 cases of superficial soft tissue/cutaneous MPE, identified across three tertiary institutions. All patients were female and three of them (3/5, 60%) were children (median age 11 years, range 6-58 years). The tumors presented as slow-growing masses of the sacrococcygeal subcutaneous soft tissues, occasionally identified after minor trauma and clinically favored to be pilonidal sinuses. Imaging showed no neuraxis connection. Macroscopically, tumors were well-circumscribed, lobulated, and solid and microscopically they exhibited typical histopathology of MPE, at least focally. Two of the tumors (2/5, 40%) showed predominantly solid or trabecular architecture with greater cellular pleomorphism, scattered giant cells, and increased mitotic activity. All tumors (5/5, 100%) showed strong diffuse immunohistochemical expression of GFAP. One tumor clustered at the category "ependymoma, myxopapillary" by methylome analysis. Two patients (2/5, 40%) had local recurrence at 8 and 30 months after the initial surgery. No patients developed metastases during the follow-up period (median 60 months, range 6-116 months). Since a subset of extra-axial MPEs behaves more aggressively, timely and accurate diagnosis is of paramount importance.

Highly Multiplexed Spatially Resolved Proteomic and Transcriptional Profiling of the Glioblastoma Microenvironment Using Archived Formalin-Fixed Paraffin-Embedded Specimens.

Glioblastoma is a heterogeneous tumor for which effective treatment options are limited and often insufficient. Few studies have examined the intratumoral transcriptional and proteomic heterogeneity of the glioblastoma microenvironment to characterize the spatial distribution of potential molecular and cellular therapeutic immunooncology targets. We applied an integrated multimodal approach comprised of NanoString GeoMx Digital Spatial Profiling, single-cell RNA-seq (scRNA-seq), and expert neuropathologic assessment to characterize archival formalin-fixed paraffin-embedded glioblastoma specimens. Clustering analysis and spatial cluster maps highlighted the intratumoral heterogeneity of each specimen. Mixed cell deconvolution analysis revealed that neoplastic and vascular cells were the prominent cell types throughout each specimen, with macrophages, oligodendrocyte precursors, neurons, astrocytes, and oligodendrocytes present in lower abundance and illustrated the regional distribution of the respective cellular enrichment scores. The spatial resolution of the actionable immunotherapeutic landscape showed that robust B7H3 gene and protein expression was broadly distributed throughout each specimen and identified STING and VISTA as potential targets. Lastly, we uncovered remarkable variability in VEGFA expression and discovered unanticipated associations between VEGFA, endothelial cell markers, hypoxia, and the expression of immunoregulatory genes, indicative of regionally distinct immunosuppressive microdomains. This work provides an early demonstration of the ability of an integrated panel-based spatial biology approach to characterize and quantify the intrinsic molecular heterogeneity of the glioblastoma microenvironment.

Expanded analysis of high-grade astrocytoma with piloid features identifies an epigenetically and clinically distinct subtype associated with neurofibromatosis type 1.

High-grade astrocytoma with piloid features (HGAP) is a recently recognized glioma type whose classification is dependent on its global epigenetic signature. HGAP is characterized by alterations in the mitogen-activated protein kinase (MAPK) pathway, often co-occurring with CDKN2A/B homozygous deletion and/or ATRX mutation. Experience with HGAP is limited and to better understand this tumor type, we evaluated an expanded cohort of patients (n = 144) with these tumors, as defined by DNA methylation array testing, with a subset additionally evaluated by next-generation sequencing (NGS). Among evaluable cases, we confirmed the high prevalence CDKN2A/B homozygous deletion, and/or ATRX mutations/loss in this tumor type, along with a subset showing NF1 alterations. Five of 93 (5.4%) cases sequenced harbored TP53 mutations and RNA fusion analysis identified a single tumor containing an NTRK2 gene fusion, neither of which have been previously reported in HGAP. Clustering analysis revealed the presence of three distinct HGAP subtypes (or groups = g) based on whole-genome DNA methylation patterns, which we provisionally designated as gNF1 (n = 18), g1 (n = 72), and g2 (n = 54) (median ages 43.5 years, 47 years, and 32 years, respectively). Subtype gNF1 is notable for enrichment with patients with Neurofibromatosis Type 1 (33.3%, p = 0.0008), confinement to the posterior fossa, hypermethylation in the NF1 enhancer region, a trend towards decreased progression-free survival (p = 0.0579), RNA processing pathway dysregulation, and elevated non-neoplastic glia and neuron cell content (p < 0.0001 and p < 0.0001, respectively). Overall, our expanded cohort broadens the genetic, epigenetic, and clinical phenotype of HGAP and provides evidence for distinct epigenetic subtypes in this tumor type.

Capturing evolving definitions of 12 select rare CNS tumors: a timely report from CBTRUS and NCI-CONNECT.

PURPOSE: Incidence, prevalence, and survival are population-based statistics describing cancer burden. The National Cancer Institute's (NCI) Comprehensive Oncology Network Evaluating Rare CNS Tumors (NCI-CONNECT) specializes in tumor biology and outcomes for 12 rare CNS tumor types selected for their importance in adults, research interest, or potential for targeted treatment. The aim of this study was to update incidence, prevalence, and survival statistics for these tumors. METHODS: The Central Brain Tumor Registry of the United States (CBTRUS) database, a combined dataset of Centers for Disease Control and Prevention's (CDC) National Program of Cancer Registries (NPCR) and NCI's Surveillance, Epidemiology and End Results (SEER) data, was used to calculate average annual age-adjusted incidence rates (AAAIR) per 100,000 population overall and by sex, race-ethnicity, and age for diagnosis years 2008-2019. Incidence time trends were calculated for diagnosis years 2004-2019. NPCR data were used to calculate relative survival rates. Point prevalence on December 31, 2019 was estimated using annual age-specific incidence and survival. RESULTS: AAAIR was 1.47 per 100,000 for these tumors combined, with highest incidence in ependymomas (AAAIR = 0.41/100,000). Most tumor types were more common in males, adults (ages 40 + years) or children (ages < 15 years), and non-Hispanic White individuals. Ependymomas were the most prevalent tumor type (19,320 cases) followed by oligodendrogliomas (14,900 cases). Ependymomas had the highest five-year survival (90.6%) and primary CNS sarcomas the lowest (7.7%). CONCLUSIONS: These data provide means to measure the impact of clinical care and evaluate new therapies and the evolving histopathology definitions in rare CNS tumor types.

Classification and Grading of Central Nervous System Tumors According to the World Health Organization 5th Edition.

The World Health Organization (WHO) released the 5th edition of its classification of central nervous system (CNS) tumors in 2021. Advances in the landscape of molecular tumor pathophysiology prompted major revisions to the previous edition released in 2016, some of which were first introduced by the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy-Not Official WHO (cIMPACT-NOW). The 2021 classification system integrates newly gained molecular insights to guide changes in tumor taxonomy and nomenclature, introduces several new types of tumors, and expands the use of molecular testing for diagnosis and grading, with a particular impact on adult-type and pediatric-type gliomas, ependymomas, and embryonal tumors. These updates aim to promote clear and accurate diagnoses, yield more reliable prognostic information, and enable the selection of optimal therapies. Familiarity with these changes will be of great importance for clinicians involved in the management of CNS tumor patients.

Platelet-derived growth factor beta is a potent inflammatory driver in paediatric high-grade glioma.

Paediatric high-grade gliomas (HGGs) account for the most brain tumour-related deaths in children and have a median survival of 12-15 months. One promising avenue of research is the development of novel therapies targeting the properties of non-neoplastic cell-types within the tumour such as tumour associated macrophages (TAMs). TAMs are immunosuppressive and promote tumour malignancy in adult HGG; however, in paediatric medulloblastoma, TAMs exhibit anti-tumour properties. Much is known about TAMs in adult HGG, yet little is known about them in the paediatric setting. This raises the question of whether paediatric HGGs possess a distinct constituency of TAMs because of their unique genetic landscapes. Using human paediatric HGG tissue samples and murine models of paediatric HGG, we demonstrate diffuse midline gliomas possess a greater inflammatory gene expression profile compared to hemispheric paediatric HGGs. We also show despite possessing sparse T-cell infiltration, human paediatric HGGs possess high infiltration of IBA1+ TAMs. CD31, PDGFRß, and PDGFB all strongly correlate with IBA1+ TAM infiltration. To investigate the TAM population, we used the RCAS/tv-a system to recapitulate paediatric HGG in newborn immunocompetent mice. Tumours are induced in Nestin-positive brain cells by PDGFA or PDGFB overexpression with Cdkn2a or Tp53 co-mutations. Tumours driven by PDGFB have a significantly lower median survival compared to PDGFA-driven tumours and have increased TAM infiltration. NanoString and quantitative PCR analysis indicates PDGFB-driven tumours have a highly inflammatory microenvironment characterized by high chemokine expression. In vitro bone marrow-derived monocyte and microglial cultures demonstrate bone marrow-derived monocytes are most responsible for the production of inflammatory signals in the tumour microenvironment in response to PDGFB stimulation. Lastly, using knockout mice deficient for individual chemokines, we demonstrate the feasibility of reducing TAM infiltration and prolonging survival in both PDGFA and PDGFB-driven tumours. We identify CCL3 as a potential key chemokine in these processes in both humans and mice. Together, these studies provide evidence for the potent inflammatory effects PDGFB has in paediatric HGGs.

Genetic driver mutations introduced in identical cell-of-origin in murine glioblastoma reveal distinct immune landscapes but similar response to checkpoint blockade.

Glioblastoma (GBM) is the most aggressive primary brain tumor. In addition to being genetically heterogeneous, GBMs are also immunologically heterogeneous. However, whether the differences in immune microenvironment are driven by genetic driver mutation is unexplored. By leveraging the versatile RCAS/tv-a somatic gene transfer system, we establish a mouse model for Classical GBM by introducing EGFRvIII expression in Nestin-positive neural stem/progenitor cells in adult mice. Along with our previously published Nf1-silenced and PDGFB-overexpressing models, we investigate the immune microenvironments of the three models of human GBM subtypes by unbiased multiplex profiling. We demonstrate that both the quantity and composition of the microenvironmental myeloid cells are dictated by the genetic driver mutations, closely mimicking what was observed in human GBM subtypes. These myeloid cells express high levels of the immune checkpoint protein PD-L1; however, PD-L1 targeted therapies alone or in combination with irradiation are unable to increase the survival time of tumor-bearing mice regardless of the driver mutations, reflecting the outcomes of recent human trials. Together, these results highlight the critical utility of immunocompetent mouse models for preclinical studies of GBM, making these models indispensable tools for understanding the resistance mechanisms of immune checkpoint blockade in GBM and immune cell-targeting drug discovery.

Multimodal single-cell analysis reveals distinct radioresistant stem-like and progenitor cell populations in murine glioma.

Radiation therapy is part of the standard of care for gliomas and kills a subset of tumor cells, while also altering the tumor microenvironment. Tumor cells with stem-like properties preferentially survive radiation and give rise to glioma recurrence. Various techniques for enriching and quantifying cells with stem-like properties have been used, including the fluorescence activated cell sorting (FACS)-based side population (SP) assay, which is a functional assay that enriches for stem-like tumor cells. In these analyses, mouse models of glioma have been used to understand the biology of this disease and therapeutic responses, including the radiation response. We present combined SP analysis and single-cell RNA sequencing of genetically-engineered mouse models of glioma to show a time course of cellular response to radiation. We identify and characterize two distinct tumor cell populations that are inherently radioresistant and also distinct effects of radiation on immune cell populations within the tumor microenvironment.

Incorporating genomic signatures into surgical and medical decision-making for elderly glioblastoma patients.

Glioblastoma (GBM) is the most common type of malignant primary brain tumor in adults. It is a uniformly fatal disease (median overall survival 16 months) even with aggressive resection and an adjuvant temozolomide-based chemoradiation regimen. Age remains an independent risk factor for a poor prognosis. Several factors contribute to the dismal outcomes in the elderly population with GBM, including poor baseline health status, differences in underlying genomic alterations, and variability in the surgical and medical management of this subpopulation. The latter arises from a lack of adequate representation of elderly patients in clinical trials, resulting in limited data on the response of this subpopulation to standard treatment. Results from retrospective and some prospective studies have indicated that resection of only contrast-enhancing lesions and administration of hypofractionated radiotherapy in combination with temozolomide are effective strategies for optimizing survival while maintaining baseline quality of life in elderly GBM patients; however, survival remains dismal relative to that in a younger cohort. Here, the authors present historical context for the current strategies used for the multimodal management (surgical and medical) of elderly patients with GBM. Furthermore, they provide insights into elderly GBM patient-specific genomic signatures such as isocitrate dehydrogenase 1/2 (IDH1/2) wildtype status, telomerase reverse transcriptase promoter (TERTp) mutations, and somatic copy number alterations including CDK4/MDM2 coamplification, which are becoming better understood and could be utilized in a clinical trial design and patient stratification to guide the development of more effective adjuvant therapies specifically for elderly GBM patients.

Application of the condensed protocol for the NIA-AA guidelines for the neuropathological assessment of Alzheimer's disease in an academic clinical practice.

AIMS: In response to concerns regarding resource expenditures required to implement fully the 2012 National Institute on Aging and the Alzheimer's Association (NIA-AA) Sponsored Guidelines for the neuropathological assessment of Alzheimer's disease (AD), we previously developed a sensitive and cost-reducing condensed protocol (CP) at the University of Washington (UW) Alzheimer's Disease Research Center (ADRC) that consolidated the recommended NIA-AA protocol into fewer cassettes requiring fewer immunohistochemical stains. The CP was not designed to replace NIA-AA protocols, but instead to make the NIA-AA criteria accessible to clinical and forensic neuropathology practices where resources limit full implementation of NIA-AA guidelines. METHODS AND RESULTS: In this regard, we developed practical criteria to instigate CP sampling and immunostaining, and applied these criteria in an academic clinical neuropathological practice. During the course of 1 year, 73 cases were sampled using the CP; of those, 53 (72.6%) contained histological features that prompted CP work-up. We found that the CP resulted in increased identification of AD and Lewy body disease neuropathological changes from what was expected using a clinical history-driven work-up alone, while saving approximately $900 per case. CONCLUSIONS: This study demonstrates the feasibility and cost-savings of the CP applied to a clinical autopsy practice, and highlights potentially unrecognised neurodegenerative disease processes in the general ageing community.

Clival paragangliomas: a report of two cases involving the midline skull base and review of the literature.

Head and neck paragangliomas are rare neuroendocrine tumors that arise from paraganglion cells of the parasympathetic nervous system. Paragangliomas arising from the midline skull base have only rarely been reported. Surgery is the mainstay of treatment and adjuvant radiation is often recommended. These tumors can rarely secrete metanephrines and normetanephrines which can complicate operative management. Here we present two cases of clival paragangliomas with unique clinical presentations and review the previous literature on skull base paragangliomas.

Clinicopathologic characteristics of metastatic esophageal carcinoma isolated to the pineal region: A case report and review of the literature.

Metastasis to the pineal region is a rare event, and esophageal adenocarcinoma metastatic to the pineal region is exceptionally rare, with only two cases reported in the current literature. Here, we characterize a third case of metastatic esophageal adenocarcinoma to the pineal region, and compare clinicopathological characteristics among all three cases. The three patients were men, with ages at neurological presentation ranging from 48 to 65years. Time from initial esophageal adenocarcinoma diagnosis to development of neurologic symptoms ranged from 12 to 23months. Neuroimaging in all cases showed an isolated enhancing pineal region mass with sizes ranging from 1.8 to 2.2cm. All cases were believed to have local control of esophageal disease prior to metastatic sequela, with initial treatment including esophageal resection with or without chemoradiation therapy. No cases had evidence of primary site disease progression at time of metastatic presentation, nor were there signs of other sites of metastasis. All patients underwent tumor excision and were referred for subsequent radiotherapy. Overall, all three cases demonstrate similar demographics, histology, and clinical presentations. In the appropriate clinical setting it is important to keep esophageal metastasis in the differential diagnosis, particularly in the setting of isolated pineal lesions.

Immunohistochemical profiling including beta-catenin in conjunctival melanocytic lesions.

Conjunctival melanocytic lesions encompass a group of clinically diverse, benign to malignant, neoplasms that may contain overlapping histopathological features, making definitive diagnosis challenging in some cases. In this series, we compared multiple immunohistochemical (IHC) markers in 11 conjunctival nevi, 10 primary acquired melanosis (PAM) lesions, and 11 conjunctival melanomas. Immunostains included the melanocytic markers HMB-45 and Melan-A, as well as the proliferative marker Ki-67. Loss of beta-catenin expression has been associated with more aggressive clinical disease in cutaneous melanoma, but its status in conjunctival melanocytic lesions is not known, therefore we incorporated beta-catenin immunohistochemical staining in our study. In this series, conjunctival melanomas had a higher Ki-67 proliferative index and HMB-45 immunoreactivity than did PAM lesions and conjunctival nevi (P<0.001). Melan-A was highly expressed in all 3 groups. Beta-catenin was more strongly expressed in melanomas and nevi than in PAM (P<0.001). There was high inter-grader reliability (Kappa=0.53). Overall, IHC labeling of HMB-45 and Ki-67 is increased in conjunctival melanomas compared to PAM or conjunctival nevi. Beta-catenin, an IHC marker previously unstudied in conjunctival melanocytic lesions, is not preferentially expressed in benign lesions and may play a different role in conjunctival atypia than it does in cutaneous melanoma.