Epithelioid glioblastoma with microglia features: potential for novel therapy

The Significance of BRAF Mutation in the Epithelioid Glioblastoma Subtype: A Systematic Literature Review and a Case Report with a Unique Intraventricular Topography

Epithelioid glioblastoma (E-GBM) is an exceedingly rare subtype of isocitrate dehydrogenase (IDH)-wildtype glioblastoma, first included in the WHO 2016 classification and characterized by a dominant population of epithelioid cells. Its histological and molecular defining features remain troublesome. The significance of BRAF mutations to pathological diagnosis and surgical outcome has drawn increasing attention given their promising potential for future adjuvant therapies. Herein, we describe a unique case of an E-GBM in the atrium of the left lateral ventricle and comprehensively analyze the importance of BRAF status in a cohort of 211 E-GBMs from the literature. Our patient was a 40-year-old man with occipital pain. His brain MRI revealed a large intraventricular tumor at the same location as a signal change found 10 years earlier with no additional follow-up. He underwent gross total tumor removal followed by conventional adjuvant treatment. Histopathological diagnosis was consistent with IDH-wildtype E-GBM WHO grade 4 with pleomorphic xanthoastrocytoma-like areas. BRAF p.V600 mutation was demonstrated in the tumoral genetic study. In the cohort analyzed, male patients predominated (63%), the median age was 32 years old, and the 5-year survival rate following diagnosis was 4.2%. BRAF mutations were found in 60.3% of the tumors overall, with this rate increasing to 78.3% in young adults (19-49 years, P < .001). Presence of BRAF mutations associated with tumor progression (P = .001), the event usually leading to death (P < .001). In conclusion, our study supports the importance of genetic BRAF p.V600 mutation analysis because its presence not only points to an E-GBM diagnosis but may also promote tumor progression.

Infantile Rosai-Dorfman Disease With Isolated Brain Lesions Disseminated to the Parenchyma and Intraventricular Ependyma, Alteration of Leukocytes as a Promotion Factor in Immune Defense, and New Proposals: A Case Report and Literature Review

The patient is a one-year-old girl referred to the hospital for an enlarged head after a 1.5-month history of two falls, followed by polydipsia, polyuria, and slow movement and growth. Three subsequent magnetic resonance imaging (MRI) examinations of the brain revealed nodular lesions disseminated in the brain parenchyma and intraventricular ependyma, resulting in obstructive hydrocephalus. Thoracic and abdominopelvic sonography showed no additional lesions. The preliminary diagnosis was a primary or metastatic neoplasm or infection. A biopsy of a lesion in the right frontal lobe was taken. The histological examination revealed features of Rosai-Dorfman disease (RDD), consisting of limited perivascular lymphoplasma cell infiltration with intervening sheets of proliferated histiocytes, with some of the histiocytes showing endocytosis of a single intact lymphocyte (emperipolesis).

Human dendritic cell subsets in the glioblastoma-associated microenvironment

Glioblastoma (GBM) is the most aggressive type of glioma (Grade IV). The presence of cytotoxic T lymphocyte (CTLs) has been associated with improved outcomes in patients with GBM, and it is believed that the activation of CTLs by dendritic cells may play a critical role in controlling the growth of GBM. DCs are professional antigen-presenting cells (APC) that orchestrate innate and adaptive anti-GBM immunity. DCs can subsequently differentiate into plasmacytoid DCs (pDC), conventional DC1 (cDC1), conventional (cDC2), and monocyte-derived DCs (moDC) depending on environmental exposure. The different subsets of DCs exhibit varying functional capabilities in antigen presentation and T cell activation in producing an antitumor response. In this review, we focus on recent studies describing the phenotypic and functional characteristics of DC subsets in humans and their respective antitumor immunity and immunotolerance roles in the GBM-associated microenvironment. The critical components of crosstalk between DC subsets that contribute significantly to GBM-specific immune responses are also highlighted in this review with reference to the latest literature. Since DCs could be prime targets for therapeutic intervention, it is worth summarizing the relevance of DC subsets with respect to GBM-associated immunologic tolerance and their therapeutic potential.

TTFields Prolonged the PFS of Epithelioid Glioblastoma Patient: A Case Report

Epithelioid glioblastoma (EGBM, classified as glioblastoma, IDH wild type, grade 4 according to the fifth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) (WHO CNS5)) is a highly aggressive malignancy, with a median progression-free survival (mPFS) of about 6 months in adults. The application of tumor-treating fields (TTFields, possessing anti-cancer capabilities via anti-mitotic effects) in the maintenance of temozolomide (TMZ) chemotherapy showed a benefit for prolonging the mPFS of newly diagnosed glioblastoma (GBM) for patients for up to 6.9 months in the EF-14 clinical trial (NCT00916409). However, studies focusing on the effect of TTFields in EGBM treatment are very limited due to the rarity of EGBM. Here, we have reported a case of a 28-year-old male (recurrent left-sided limb twitching for 1 month and dizziness for 1 week) diagnosed with EGBM. A right frontal lobe occupancy was detected by magnetic resonance imaging (MRI), and a total tumor resection was performed. Meanwhile, a postoperative histopathology test, including immunohistochemistry and molecular characterization, was conducted, and the results revealed a BRAF V600E mutation, no co-deletion of 1p and 19q, and negative O-6-methylguanine DNA methyltransferase (MGMT) promoter methylation. Then, chemoradiotherapy was conducted, and TTFields and TMZ were performed sequentially. Notably, a long-term PFS of 34 months and a Karnofsky Performance Scale (KPS) of 90 were achieved by the patient on TTFields combined with TMZ, whose average daily usage of TTFields was higher than 90%.

Primary cerebral epithelioid angiosarcoma: a case report

BACKGROUND

Primary cerebral epithelioid angiosarcoma (PCEA) is a rare malignant tumor of the central nervous system. To the best of our knowledge, only three cases have been reported in the English language literature thus far.

CASE PRESENTATION

Here, we report a fourth case in a 73-year-old man admitted for headache. Radiological examination revealed a mass in the right occipital lobe, which was removed by right occipital craniotomy. Histopathological examination revealed epithelioid angiosarcoma. The patient received radiotherapy after resection but survived for only nine months due to recurrence of the tumor and his declining further surgery.

CONCLUSIONS

In this report, we add to the knowledge base on this exceedingly rare tumor, review the small number of relevant cases published previously, and analyze and summarize the clinical and pathological characteristics, treatment options and prognosis of this cancer.

Dimorphic glioblastoma with glial and epithelioid phenotypes: Clonal evolution and immune selection

Purpose

Epithelioid glioblastoma is an unusual histologic variant of malignant glioma. The present study investigates both the genomic and transcriptomic determinants that may promote the development of this tumor.

Methods

Whole-exome sequencing (WES) and whole-transcriptome sequencing (WTS) were performed on an epithelioid glioblastoma, along with a specific bioinformatic pipeline to generate electronic karyotyping and investigate the tumor immune microenvironment. Microdissected sections containing typical glioblastoma features and epithelioid morphology were analyzed separately using the same methodologies.

Results

An epithelioid glioblastoma, with immunopositivity for GFAP, Olig-2, and ATRX but negative for IDH-1 and p53, was identified. The tumor cell content from microdissection was estimated to be 85-90% for both histologic tumor components. WES revealed that both glioma and epithelioid sections contained identical point mutations in PTEN, RB1, TERT promoter, and TP53. Electronic karyotype analysis also revealed similar chromosomal copy number alterations, but the epithelioid component showed additional abnormalities that were not found in the glioblastoma component. The tumor immune microenvironments were strikingly different and WTS revealed high levels of transcripts from myeloid cells as well as M1 and M2 macrophages in the glioma section, while transcripts from CD4+ lymphocytes and NK cells predominated in the epithelioid section.

Conclusion

Epithelioid glioblastoma may be genomically more unstable and oncogenically more advanced, harboring an increased number of mutations and karyotype abnormalities, compared to typical glioblastomas. The tumor immune microenvironment is also different.

Microglia and Brain Macrophages as Drivers of Glioma Progression

Evidence is accumulating that the tumour microenvironment (TME) has a key role in the progression of gliomas. Non-neoplastic cells in addition to the tumour cells are therefore finding increasing attention. Microglia and other glioma-associated macrophages are at the centre of this interest especially in the context of therapeutic considerations. New ideas have emerged regarding the role of microglia and, more recently, blood-derived brain macrophages in glioblastoma (GBM) progression. We are now beginning to understand the mechanisms that allow malignant glioma cells to weaken microglia and brain macrophage defence mechanisms. Surface molecules and cytokines have a prominent role in microglia/macrophage-glioma cell interactions, and we discuss them in detail. The involvement of exosomes and microRNAs forms another focus of this review. In addition, certain microglia and glioma cell pathways deserve special attention. These "synergistic" (we suggest calling them "Janus") pathways are active in both glioma cells and microglia/macrophages where they act in concert supporting malignant glioma progression. Examples include CCN4 (WISP1)/Integrin α6β1/Akt and CHI3L1/PI3K/Akt/mTOR. They represent attractive therapeutic targets.

Glioma targeted therapy: insight into future of molecular approaches

Gliomas are the common type of brain tumors originating from glial cells. Epidemiologically, gliomas occur among all ages, more often seen in adults, which males are more susceptible than females. According to the fifth edition of the WHO Classification of Tumors of the Central Nervous System (WHO CNS5), standard of care and prognosis of gliomas can be dramatically different. Generally, circumscribed gliomas are usually benign and recommended to early complete resection, with chemotherapy if necessary. Diffuse gliomas and other high-grade gliomas according to their molecule subtype are slightly intractable, with necessity of chemotherapy. However, for glioblastoma, feasible resection followed by radiotherapy plus temozolomide chemotherapy define the current standard of care. Here, we discuss novel feasible or potential targets for treatment of gliomas, especially IDH-wild type glioblastoma. Classic targets such as the p53 and retinoblastoma (RB) pathway and epidermal growth factor receptor (EGFR) gene alteration have met failure due to complex regulatory network. There is ever-increasing interest in immunotherapy (immune checkpoint molecule, tumor associated macrophage, dendritic cell vaccine, CAR-T), tumor microenvironment, and combination of several efficacious methods. With many targeted therapy options emerging, biomarkers guiding the prescription of a particular targeted therapy are also attractive. More pre-clinical and clinical trials are urgently needed to explore and evaluate the feasibility of targeted therapy with the corresponding biomarkers for effective personalized treatment options.

Clinicopathological characteristics and treatment outcomes of epithelioid glioblastoma

Epithelioid glioblastoma is a new variant of glioblastoma that has been recently recognized in the 2016 WHO classification of brain tumors. Given the rarity of epithelioid glioblastoma, the clinical characteristics, pathological features, radiological findings, and treatment outcomes are still not well characterized. Therefore, we identified eighty-four epithelioid glioblastoma cases to investigate these characteristics and identify the possible prognostic factors of survival. There were 55 male and 29 female patients with a mean age of 33.6 years. Headache (77.3%) was the most common clinical symptom, and other common symptoms included nausea or vomiting (34%), dizziness (20.5%), seizures (13.6%), and limb weakness (13.6%). Most lesions (88.1%) were located in cerebral lobes, especially in the frontal lobe and temporal lobe. One hundred percent of the patients were IDH1 wild-type (75/75) and INI-1 positive (58/58), and 57.3% (47/82) of patients harbored BRAF^V600E mutation. The median overall survival (OS) of all patients was 10.5 months. Patients who received chemotherapy (p = 0.006) or radiotherapy (p = 0.022) had a longer survival than patients who did not. In addition, the K-M curve showed that the BRAF^V600E mutation status was not associated with survival (p = 0.724). These findings may assist clinicians with better understanding and management of epithelioid glioblastoma.