Single-cell RNA sequencing reveals evolution of immune landscape during glioblastoma progression.

Glioblastoma (GBM) is an incurable primary malignant brain cancer hallmarked with a substantial protumorigenic immune component. Knowledge of the GBM immune microenvironment during tumor evolution and standard of care treatments is limited. Using single-cell transcriptomics and flow cytometry, we unveiled large-scale comprehensive longitudinal changes in immune cell composition throughout tumor progression in an epidermal growth factor receptor-driven genetic mouse GBM model. We identified subsets of proinflammatory microglia in developing GBMs and anti-inflammatory macrophages and protumorigenic myeloid-derived suppressors cells in end-stage tumors, an evolution that parallels breakdown of the blood-brain barrier and extensive growth of epidermal growth factor receptor+ GBM cells. A similar relationship was found between microglia and macrophages in patient biopsies of low-grade glioma and GBM. Temozolomide decreased the accumulation of myeloid-derived suppressor cells, whereas concomitant temozolomide irradiation increased intratumoral GranzymeB+ CD8+T cells but also increased CD4+ regulatory T cells. These results provide a comprehensive and unbiased immune cellular landscape and its evolutionary changes during GBM progression.

Inhibition of the epigenetically activated miR-483-5p/IGF-2 pathway results in rapid loss of meningioma tumor cell viability.

PURPOSE: Meningioma is the most common primary central nervous system tumor often causing serious complications, and presently no medical treatment is available. The goal of this study was to discover miRNAs dysregulated in meningioma, and explore miRNA-associated pathways amenable for therapeutic interventions. METHODS: Small RNA sequencing was performed on meningioma tumor samples to study grade-dependent changes in microRNA expression. Gene expression was analyzed by chromatin marks, qRT-PCR and western blot. miRNA modulation, anti-IGF-2 neutralizing antibodies, and inhibitors against IGF1R were evaluated in a tumor-derived primary cultures of meningioma cells. RESULTS: Meningioma tumor samples showed high, grade-dependent expression of miR-483-5p, associated with high mRNA and protein expression of its host gene IGF-2. Inhibition of miR-483-5p reduced the growth of cultured meningioma cells, whereas a miR-483 mimic increased cell proliferation. Similarly, inhibition of this pathway with anti-IGF-2 neutralizing antibodies reduced meningioma cell proliferation. Small molecule tyrosine kinase inhibitor blockade of the IGF-2 receptor (IGF1R) resulted in rapid loss of viability of cultured meningioma tumor-derived cells, suggesting that autocrine IGF-2 feedback is obligatory for meningioma tumor cell survival and growth. The observed IGF1R-inhibitory IC50 for GSK1838705A and ceritinib in cell-based assays along with the available pharmacokinetics data predicted that effective drug concentration could be achieved in vivo as a new medical treatment of meningioma. CONCLUSION: Meningioma cell growth is critically dependent on autocrine miR-483/IGF-2 stimulation and the IGF-2 pathway provides a feasible meningioma treatment target.

Green Discoloration of Human Postmortem Brains: Etiologies and Mechanisms of Discoloration.

ABSTRACT: A variety of gross discolorations of human postmortem brains is occasionally encountered and can have diagnostic implications. We describe 3 cases of green discoloration of the human brain observed on postmortem examination. Two patients who succumbed shortly after administration of methylene blue (MB) showed diffuse green discoloration that was detectable as early as 24 hours and was seen for at least 48 hours after MB administration. Green discoloration was largely in cortical and deep gray matter structures with relative sparing of the white matter. In contrast, a patient with severe hyperbilirubinemia who died after intracerebral hemorrhage showed localized bright green bile stained brain parenchyma in the areas surrounding the hemorrhage. We highlight the distinct patterns of discoloration in different causes of green brain discoloration, including MB, bile staining, and hydrogen sulfide poisoning. Recognition of these patterns by practicing pathologists can be used to differentiate between these etiologies and allow correct interpretation in both the medical and forensic autopsy settings.

A high-grade glioma with SOS1 amplification.

The molecular alterations underlying progression of low-grade glial/glioneuronal tumors remain to be elucidated. We present a case of a 56-year-old male with an enhancing left temporal lobe tumor. Histology revealed a high-grade glioma adjacent to a low-grade glioneuronal component with abundant Rosenthal fibers, focal eosinophilic granular bodies, and CD34-positive neurons. The tumor was negative for IDH1 (R132H), BRAF-V600E, and the KIAA1549-BRAF fusion. Comparative genomic hybridization detected a large amplification (> 15 copies) of the Son of Sevenless 1 (SOS1) gene, a component of the MAPK pathway. Although activating mutations in the MAPK pathway occur frequently in gliomas and glioneuronal tumors, SOS1 gene amplification has not been reported previously. This case indicates another potential mechanism for MAPK activation in glial tumors.

Granular cell tumor of the infundibulum: a systematic review of MR-radiography, pathology, and clinical findings.

INTRODUCTION: Granular cell tumors (GCTs) of the infundibulum are rare in practice and literature, resulting in a lack of evidence-based standard of care. We present two characteristic cases from our institution and perform a systematic review of the existing literature to further elucidate the presentation of this tumor and guide management. METHODS: A systematic literature search was conducted according to PRISMA guidelines, yielding 42 total individual reported GCTs suitable for evaluation. Available clinical presentation, magnetic resonance imaging (MRI) characteristics, pathology, surgical approaches, and outcomes were charted. We measured frequencies of clinical characteristics and performed an outcome comparison of open versus endoscopic surgical treatment. RESULTS: In this pooled dataset, GCT incidence was higher in females than males (3:1). Clinical presentation peaked in the fourth decade with tumor-related symptoms. MRI appearance was characterized by T1 isointensity (50%) and T2 hypointensity or isointensity (52%) with gadolinium contrast enhancement (74%). Histopathology demonstrated positive staining for PAS, PAS-D, S100, CD68, and TTF1. In a simple uncontrolled analysis, patients who underwent endoscopic surgery experienced more symptom improvement (p = 0.006) and lower incidence of new diabetes insipidus postoperatively (p = 0.047) versus patients who underwent open microsurgery. CONCLUSIONS: This first comprehensive review of GCTs of the infundibulum corroborates existing data and adds significant new MR-radiological information to the literature, notably a typical tumor appearance of T1 isointensity, T2 iso- to hypointensity, and gadolinium contrast enhancement. Future prospective studies should be conducted to validate our findings.

Biphasic IDH1 phenotype in a diffusely infiltrating glioma: implications for pathogenesis, treatment and prognosis.

Recent studies suggest isocitrate dehydrogenase 1 (IDH1) mutations are early events in gliomagenesis, given their frequent occurrence in low-grade gliomas, diffuse expression within neoplastic cells, and lack of evidence for preceding TP53 mutations or 1p/19q co-deletion. We present an infiltrating glioma with mixed oligoastroglial morphology and biphasic molecular phenotype. Areas resembling oligodendroglioma by histology expressed mutant IDH1-R132H, and strong ATRX, Olig2, and PDGFR-α by immunohistochemistry. In contrast, astrocytic areas completely lacked the IDH1-R132H mutation, showed loss of nuclear ATRX expression, and only weakly expressed Olig2 and PDGFR-α. Co-deletion of 1p/19q was evident throughout, while p53 expression was largely negative. This case suggests that 1p/19q co-deletion may rarely precede IDH1 mutations or that IDH1 mutations may be secondarily lost, as demonstrated by IDH1-R132H positive and negative cells in a glioma with diffuse 1p/19q co-deletion. The uniquely biphasic molecular phenotype of this tumor supports the rare existence of true mixed oligoastrocytomas that may have significant prognostic and therapeutic implications. The case highlights the variable sequence of key molecular aberrations in gliomagenesis and the difficulty of targeting treatment to genetic profiles in inherently heterogeneous neoplasms.

Identification of a small molecule that induces ATG5-and-cathepsin-l-dependent cell death and modulates polyglutamine toxicity.

Non-apoptotic cell death mechanisms are largely uncharacterized despite their importance in physiology and disease [1]. Here we sought to systematically identify non-apoptotic cell death pathways in mammalian cells. We screened 69,612 compounds for those that induce non-canonical cell death by counter screening in the presence of inhibitors of apoptosis and necrosis. We further selected compounds that require active protein synthesis for inducing cell death. Using this tiered approach, we identified NID-1 (Novel Inducer of Death-1), a small molecule that induces an active, energy-dependent cell death in diverse mammalian cell lines. NID-1-induced death required components of the autophagic machinery, including ATG5, and the lysosomal hydrolase cathepsin L, but was distinct from classical macroautophagy. Since macroautophagy can prevent cell death in several contexts, we tested and found that NID-1 suppressed cell death in a cell-based model of Huntington's disease, suggesting that NID-1 activates a specific pathway. Thus the discovery of NID-1 identifies a previously unexplored cell death pathway, and modulating this pathway may have therapeutic applications. Furthermore, these findings provide a proof-of-principle for using chemical screening to identify novel cell death paradigms.

Intracranial Metastasis of Extracranial Chondrosarcoma: Systematic Review With Illustrative Case.

BACKGROUND: Cerebral chondrosarcoma metastases are rare and aggressive neoplasms. The rarity of presentation has precluded rigorous analysis of diagnosis, risk factors, treatment, and survival. We analyzed every reported case through exhaustive literature review. We further present the first case with Maffucci syndrome. METHODS: Three databases, PubMed, Embase, and Google Scholar, and crossed references were queried for cerebral chondrosarcoma metastases. Extracted variables included demographics, risk factors, tumor characteristics, interventions, and outcomes. Univariate and multivariate analyses were performed. RESULTS: Fifty-six patients were included from 1,489 literature results. The average age at brain metastasis was 46.6±17.6 years and occurred at a median of 24±2.8 months from primary diagnosis. Primary tumor histology (dedifferentiated 5.0±1.5 months, mesenchymal 24±3.0 months, conventional 41±7.4 months, p<0.05) and grade (low grade 54±16.7 months vs. high-grade 10±6.4 months, p<0.001) correlated with time interval until brain metastasis. A multiple enchondromatosis syndrome occurred in 13.2% of cases. At time of brain metastases diagnosis, extracranial metastases were identified in 76.2% of cases. Median survival after the development of brain metastasis was 2.0±0.78 months with a 1-year survival of 10.0%. On regression analysis, surgery reduced brain metastasis mortality risk and radiation trended towards reduced mortality risk (surgery: hazard ratio [HR] 0.22, 95% confidence interval [CI] 0.064-0.763, p=0.017; radiation: HR 0.31, 95% CI 0.091-1.072, p=0.064). CONCLUSION: We present a systematic review of cerebral chondrosarcoma metastases. Primary tumor histology and grade correlate with time until cerebral metastasis. Following cerebral metastasis, these tumors have poor prognosis and modestly benefit from surgery.

Driver Mutations Dictate the Immunologic Landscape and Response to Checkpoint Immunotherapy of Glioblastoma.

The composition of the tumor immune microenvironment (TIME) is considered a key determinant of patients' response to immunotherapy. The mechanisms underlying TIME formation and development over time are poorly understood. Glioblastoma (GBM) is a lethal primary brain cancer for which there are no curative treatments. GBMs are immunologically heterogeneous and impervious to checkpoint blockade immunotherapies. Utilizing clinically relevant genetic mouse models of GBM, we identified distinct immune landscapes associated with expression of EGFR wild-type and mutant EGFRvIII cancer driver mutations. Over time, accumulation of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) was more pronounced in EGFRvIII-driven GBMs and was correlated with resistance to PD-1 and CTLA-4 combination checkpoint blockade immunotherapy. We determined that GBM-secreted CXCL1/2/3 and PMN-MDSC-expressed CXCR2 formed an axis regulating output of PMN-MDSCs from the bone marrow leading to systemic increase in these cells in the spleen and GBM tumor-draining lymph nodes. Pharmacologic targeting of this axis induced a systemic decrease in the numbers of PMN-MDSC, facilitated responses to PD-1 and CTLA-4 combination checkpoint blocking immunotherapy, and prolonged survival in mice bearing EGFRvIII-driven GBM. Our results uncover a relationship between cancer driver mutations, TIME composition, and sensitivity to checkpoint blockade in GBM and support the stratification of patients with GBM for checkpoint blockade therapy based on integrated genotypic and immunologic profiles.

Cerebral Metastases in Appendiceal Cancer: Comprehensive Review and Report of Rare Medullary Carcinoma Histology.

Appendiceal cancer is an extremely rare malignancy, and its metastatic spread to the brain is even more unusual. We describe a 47-year-old female who presented with a rare cerebral appendiceal carcinoma metastasis, a case that is further remarkable for representing the first histologic diagnosis of primary medullary carcinoma in the appendix. Based on a comprehensive review of the English literature using PubMed, Embase, and Google Scholar, only six other cases of cerebral appendiceal metastases have been described.

Cytogenetic and Molecular Characterization of IDH-Wildtype Glioblastomas and Grade 4 IDH-Mutant Astrocytomas with Unusual Histology.

Glioblastoma (GBM) is a highly heterogenous tumor. Though several well-defined histological patterns of GBMs are known, these are infrequent, and the molecular correlates of several of these histological patterns are not well understood. We identified 31 adult-type infiltrating grade 4 gliomas with unusual histology in our institutional archives from 2016 to 2020, including tumors with a preponderant component of giant cell (n = 15), gemistocytes (n = 6), spindle cells (n = 5), small cells (n = 3), and ependymoma-like features (n = 2). We performed molecular and cytogenetic profiles of IDH-wildtype GBMs with unusual histology and compared to 48 tumors with conventional histology. We found that the majority (85%) of giant cell GBM had increased numbers of whole chromosome loss and genomic haploidization compared to conventional GBMs and other variants. Furthermore, we identified a genetically confirmed GBM with prominent ependymal features, indicating that glial tumors with ependymal features should be considered in the differential diagnosis of GBM. We also identified 6 IDH-mutant grade 4 astrocytomas with unusual histology and similar molecular and cytogenetic profiles to conventional appearing grade 4 IDH-mutant astrocytomas. These findings emphasize the role of molecular/cytogenetic analyses in the diagnostic clarification of GBMs with unusual histological patterns, refine the classification of unusual GBMs, and potentially pave the way for personalized therapies.

Primary Central Nervous System Anaplastic Large Cell Lymphoma, ALK Positive.

OBJECTIVES: Primary central nervous system anaplastic large cell lymphoma, anaplastic lymphoma kinase positive (primary CNS ALCL, ALK+) is a rare CNS lymphoma whose description is limited to case reports. These tumors have a variable clinical course, and prognosis is primarily determined by age. We present the largest case series to date of primary CNS ALCL, ALK+, with observational data. METHODS: A retrospective search of multiple academic centers was performed to identify cases of primary CNS ALCL, ALK+. We also performed a review of published cases of primary CNS ALCL, ALK+. Clinical history, radiography, pathology, and genetic testing data were obtained to determine the prognostic implications in the context of clinical course. RESULTS: We identified three cases of primary CNS ALCL, ALK+ from our databases. A literature review identified 30 published reports of 31 individual cases. Clinical features for the combined 34 cases included a median age of 18.5 years, with a male to female ratio of 4.7:1, and the most common symptom was headache. Genetic studies demonstrated an ALK rearrangement by fluorescence in situ hybridization, and a gene fusion assay confirmed an NPM1-ALK gene fusion in one case. CONCLUSIONS: We present the largest case series to date of a rare primary CNS lymphoma with additional diagnostic and clinical information.

Mutant huntingtin alters cell fate in response to microtubule depolymerization via the GEF-H1-RhoA-ERK pathway.

Cellular responses to drug treatment show tremendous variations. Elucidating mechanisms underlying these variations is critical for predicting therapeutic responses and developing personalized therapeutics. Using a small molecule screening approach, we discovered how a disease causing allele leads to opposing cell fates upon pharmacological perturbation. Diverse microtubule-depolymerizing agents protected mutant huntingtin-expressing cells from cell death, while being toxic to cells lacking mutant huntingtin or those expressing wild-type huntingtin. Additional neuronal cell lines and primary neurons from Huntington disease mice also showed altered survival upon microtubule depolymerization. Transcription profiling revealed that microtubule depolymerization induced the autocrine growth factor connective tissue growth factor and activated ERK survival signaling. The genotype-selective rescue was dependent upon increased RhoA protein levels in mutant huntingtin-expressing cells, because inhibition of RhoA, its downstream effector, Rho-associated kinase (ROCK), or a microtubule-associated RhoA activator, guanine nucleotide exchange factor-H1 (GEF-H1), all attenuated the rescue. Conversely, RhoA overexpression in cells lacking mutant huntingtin conferred resistance to microtubule-depolymerizer toxicity. This study elucidates a novel pathway linking microtubule stability to cell survival and provides insight into how genetic context can dramatically alter cellular responses to pharmacological interventions.

Prognostic factors in Tumefactive demyelinating lesions: A retrospective study.

INTRODUCTION: Demyelinating lesions occasionally present as mass-like lesions on imaging, raising concern for malignancy. The disease course of such tumefactive demyelinating lesions (TDLs) is still being defined. METHODS: We retrospectively analyzed 21 patients with new-onset neurologic symptoms and mass-like lesions on brain magnetic resonance imaging (MRI), which resulted in biopsy-proven diagnoses of demyelination. 18 patients had a median follow-up of 52 months. The clinical, radiologic and histologic features were associated with disease course. RESULTS: An aggressive disease course (ADC) was noted in 33% of the patients and was associated with an initial largest lesion size ≥35 mm (p = 0.0007), mass effect (p = 0.01) and perilesional edema (p = 0.01) on MRI. Age 30 years and older, at presentation (p = 0.05), as well as the absence of a prior tonsillectomy (p = 0.0128) were also associated with an ADC. CONCLUSIONS: We identified several factors, including initial larger lesion size, mass effect and perilesional edema on MRI, presentation after 30 years of age and the absence of a prior tonsillectomy, that predict an ADC in patients presenting with TDLs. These predictors of disease course can help guide patient follow-up and stratification for intervention.

Neuroglial heterotopia of the middle ear: A case series and systematic literature review.

BACKGROUND: The differential diagnosis for mass forming lesions of the middle ear is broad. While uncommon, neuroglial heterotopias can occur in the middle ear and can be a source of diagnostic confusion for clinician, radiologist, and pathologist alike. METHODS: We identified three cases of neuroglial heterotopia of the middle ear in our institutional archives from 2000 to 2020 and performed extensive histological and immunohistochemical characterization of the three lesions. We conducted a systematic literature review to identify 27 cases published in the English literature between the years 1980 and 2020. Only cases with histological verification of neuroglial heterotopia specifically involving the middle ear were included. We compiled the clinical, radiological, and histopathological findings for all 30 cases. RESULTS: Patients most frequently presented with chronic otitis media (40%), hearing loss (40%), or prior history of ear surgery or trauma (13%). The median age at surgery was 49 years with a male predominance (M:F 2:1); however, a bimodal age distribution was noted with an earlier onset (11 years or younger) in a subset of patients. Immunohistochemical characterization showed mature neuronal and reactive glial populations with low Ki67 proliferation index and chronic inflammatory infiltrates. There was no neuronal dysplasia or glial atypia, consistent with benign, nonneoplastic, mature glioneuronal tissue. CONCLUSION: Immunohistochemical characterization of these lesions and clinical follow-up confirms their benign natural history. Potential etiologies include developmental misplacement, trauma, and chronic inflammation/ reactive changes resulting in sequestered encephalocele.

GCB-type is a favorable prognostic factor in primary CNS diffuse large B-cell lymphomas.

Primary CNS lymphomas (PCNSLs) are aggressive diffuse large B-cell lymphomas (DLBCLs) limited to the CNS that generally have a poor prognosis. Classification of DLBCL into germinal center B-cell (GCB) and activated B-cell (non-GCB) subtypes has prognostic value in systemic DLBCL, with GCB-type having a better prognosis. The aim of this study was to determine whether GCB versus non-GCB classification in PCNSLs has similar prognostic value. We analyzed clinical, radiological and histologic data from 24 patients with biopsy confirmed DLBCL of the CNS with classification into GCB versus non-GCB subtypes. We found that after a median follow-up of 15 months, only 39% of patients with non-GCB-type PCNS DLBCL were alive, whereas all patients with GCB-type were alive. Non-GCB-type had a median survival of 11 months, whereas all GCB-type patients were alive after a median follow-up of 22 months. As previously reported, we also found that patients younger than 70 years had longer survival (median 29 months) compared to older patients (median 8.8 months). There was no statistically significant difference between the ages, gender, focality, size or location of lesions, or treatment of non-GCB and GCB-type patients. Our findings suggest that classifying PCNSLs into GCB versus non-GCB subtype using the Hans algorithm may help stratify patients into two groups with different prognosis.

A case of statin-associated immune-mediated necrotizing myopathy with atypical biopsy features.

Statin-associated immune-mediated necrotizing myopathy (IMNM) is a rare presentation of a statin-associated myopathy. Patients usually present with muscle weakness and pain in the setting of statin use with elevated creatine kinase (CK) levels and a positive anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) antibody. Muscle biopsies typically show necrosis, CD68+ macrophages, and minimal lymphocytes. We present a case of a 67-year-old woman who had 2 months of progressive weakness and bilateral lower extremity pain after initiating atorvastatin therapy with symptoms persisting after statin cessation. She was found to have high anti-HMGCR antibody titers, and the biopsy of the rectus femoris muscle showed a prominent endomysial inflammatory cell infiltrate with necrotic and regenerative fibers and an atypical extensive inflammatory infiltrate composed of both CD4+ helper T cells and CD8+ cytotoxic T cells. She showed symptom resolution and normalization of CK levels and inflammatory markers with treatment involving a prolonged prednisone taper and a brief course of azathioprine, which was stopped because of the adverse effects.

EGFRvIII tumorigenicity requires PDGFRA co-signaling and reveals therapeutic vulnerabilities in glioblastoma.

Focal amplification of epidermal growth factor receptor (EGFR) and its ligand-independent, constitutively active EGFRvIII mutant form are prominent oncogenic drivers in glioblastoma (GBM). The EGFRvIII gene rearrangement is considered to be an initiating event in the etiology of GBM, however, the mechanistic details of how EGFRvIII drives cellular transformation and tumor maintenance remain unclear. Here, we report that EGFRvIII demonstrates a reliance on PDGFRA co-stimulatory signaling during the tumorigenic process in a genetically engineered autochthonous GBM model. This dependency exposes liabilities that were leveraged using kinase inhibitors treatments in EGFRvIII-expressing GBM patient-derived xenografts (PDXs), where simultaneous pharmacological inhibition of EGFRvIII and PDGFRA kinase activities is necessary for anti-tumor efficacy. Our work establishes that EGFRvIII-positive tumors have unexplored vulnerabilities to targeted agents concomitant to the EGFR kinase inhibitor repertoire.

Progressive Multifocal Leukoencephalopathy After Chimeric Antigen Receptor T-Cell Therapy for Recurrent Non-Hodgkin Lymphoma.

Chimeric antigen receptor (CAR) T-cell therapy targeting cluster of differentiation (CD)19 has had a transformative impact on patient outcomes in a subset of patients with relapsed/refractory non-Hodgkin lymphoma. We present a patient with refractory large B-cell lymphoma in complete remission for 2 years following treatment with CD19-targeted CAR T-cell therapy, who presented with 2 weeks of progressive aphasia. Imaging revealed a left occipital brain lesion and biopsy demonstrated features diagnostic of progressive multifocal leukoencephalopathy. Further evaluation revealed severe hypogammaglobulinemia and a low CD4 count. She was treated with pembrolizumab and intravenous immunoglobulin resulting in decreased cerebrospinal fluid viral load without clinical improvement and died 8 weeks after presentation. This case highlights that there is potential for severe opportunistic infections after CAR T-cell therapy, including fatal progressive multifocal leukoencephalopathy. Strategies to enhance post-treatment immune reconstitution are essential to further harness the unique potency of CAR T-cell therapy.