Tumor microenvironment in a minipig model of spinal cord glioma

BACKGROUND

Spinal cord glioma (SCG) is considered an orphan disease that lacks effective treatment options with margins that are surgically inaccessible and an overall paucity of literature on the topic. The tumor microenvironment is a critical factor to consider in treatment and modeling design, especially with respect to the unresectable tumor edge. Recently, our group developed a high-grade spinal cord glioma (SCG) model in Göttingen minipigs.

METHODS

Immunofluorescence and ELISA were performed to explore the microenvironmental features and inflammation cytokines in this minipig SCG model. Protein carbonyl assay and GSH/GSSG assay were analyzed in the core and edge lesions in the minipig SCG model. The primary core and edge cells proliferation rate were shown in vitro, and the xenograft model in vivo.

RESULTS

We identified an elevated Ki-67 proliferative index, vascular and pericyte markers, CD31 and desmin in the tumor edge as compared to the tumor core. In addition, we found that the tumor edge demonstrated increased pro-inflammatory and gliomagenic cytokines including TNF-α, IL-1β, and IL-6. Furthermore, the mediation of oxidative stress is upregulated in the tumor edge. Hypoxic markers had statistically significant increased staining in the tumor core, but were notably still present in the tumor edge. The edge cells cultures derived from SCG biopsy also demonstrated an increased proliferative rate compared to core cell cultures in a xenotransplantation model.

CONCLUSIONS

Our study demonstrates heterogeneity in microenvironmental features in our minipig model of high-grade SCG, with a phenotype at the edge showing increased oxidative stress, proliferation, inflammatory cytokines, neovascularization, and decreased but present staining for hypoxic markers. These findings support the utility of this model as a means for investigating therapeutic approaches targeting the more aggressive and surgically unresectable tumor border.

Using Brain Tumor MRI Structured Reporting to Quantify the Impact of Imaging on Brain Tumor Boards

Multidisciplinary tumor boards (TB) are an essential part of brain tumor care, but quantifying the impact of imaging on patient management is challenging due to treatment complexity and a lack of quantitative outcome measures. This work uses a structured reporting system for classifying brain tumor MRIs, the brain tumor reporting and data system (BT-RADS), in a TB setting to prospectively assess the impact of imaging review on patient management. Published criteria were used to prospectively assign three separate BT-RADS scores (an initial radiology report, secondary TB presenter review, and TB consensus) to brain MRIs reviewed at an adult brain TB. Clinical recommendations at TB were noted and management changes within 90 days after TB were determined by chart review. In total, 212 MRIs in 130 patients (median age = 57 years) were reviewed. Agreement was 82.2% between report and presenter, 79.0% between report and consensus, and 90.1% between presenter and consensus. Rates of management change increased with increasing BT-RADS scores (0-3.1%, 1a-0%, 1b-66.7%, 2-8.3%, 3a-38.5%, 3b-55.9, 3c-92.0%, and 4-95.6%). Of 184 (86.8%) cases with clinical follow-up within 90 days after the tumor board, 155 (84.2%) of the recommendations were implemented. Structured scoring of MRIs provides a quantitative way to assess rates of agreement interpretation alongside how often management changes are recommended and implemented in a TB setting.

Immune niches in brain metastases contain TCF1+ stem-like T cells, are associated with disease control and are modulated by preoperative SRS

The CD8+ T-cell response is prognostic for survival outcomes in several tumor types. However, whether this extends to tumors in the brain, an organ with barriers to T cell entry, remains unclear. Here, we analyzed immune infiltration in 67 brain metastasis (BrM) and found high frequencies of PD1+ TCF1+ stem-like CD8+ T-cells and TCF1- effector-like cells. Importantly, the stem-like cells aggregate with antigen presenting cells in immune niches, and niches were prognostic for local disease control. Standard of care for BrM is resection followed by stereotactic radiosurgery (SRS), so to determine SRS's impact on the BrM immune response, we examined 76 BrM treated with pre-operative SRS (pSRS). pSRS acutely reduced CD8+ T cells at 3 days. However, CD8+ T cells rebounded by day 6, driven by increased frequency of effector-like cells. This suggests that the immune response in BrM can be regenerated rapidly, likely by the local TCF1+ stem-like population.

MODL-28. DEVELOPING A STRATEGY FOR MODELING HIGH-GRADE GLIOMA IN GӦTTINGEN MINIPIGS

BACKGROUND

The current literature does not describe a reproducible large animal model of intracranial high-grade glioma (HGG). Prior work has demonstrated the feasibility of inducing HGG de-novo in rodents by targeting specific oncogenic pathways. Here we report our approach to the production of supratentorial HGG in a series of minipigs through lentiviral gene transfer and subsequent initial characterization of a porcine glioma cell line.

METHODS

Four minipigs received injections into the subcortical white matter using a combination of lentiviral vectors expressing platelet-derived growth factor beta (PDGF-B), HRAS, and shRNA-p53. Animals underwent behavioral monitoring through porcine neurobehavioral scoring (PNS) and veterinary monitoring. Magnetic resonance imaging (MRI) was conducted at endpoint prior to necropsy. Post-mortem tissue biopsies underwent tissue culture and neuropathologic evaluation with hematoxylin and eosin (H&E) staining, immunohistochemistry, and immunofluorescent staining. Data are presented using appropriate statistical tests where relevant and descriptive statistics.

RESULTS

Two pigs received 50ul injections and reached endpoint by the end of post-operative week 1 and 2. Two pigs received 25 ul injections and were asymptomatic until a pre-determined endpoint of 4 weeks. MRI scans at endpoint demonstrated contrast enhancing, mass forming lesions at the site of injection with evidence of hemorrhage and perilesional edema, consistent with high-grade glioma. On H&E staining high-grade glioma growth was identified in 100% of animals. We observed immunopositivity for tumor markers GFAP, OLIG2, NG2, SOX2, and PDGFRA, as well as redox markers, and microenvironmental features consistent with high-grade glioma. Porcine glioma cell cultures were found to have significantly greater proliferative rate compared to control, and demonstrated GFAP, OLIG2, PDGFRA, and CD68 immunopositivity.

CONCLUSIONS

Lentiviral gene transfer represents a feasible strategy for glioma modeling in the Gӧttingen minipig. With our described methodology, we present a realistic strategy for reproducible modeling of intracranial glioma as a platform for preclinical neurosurgical development programs.

Abstract 1609: Oxidative stress triggers tumor edge progression of tumor microenvironment in the minipig spinal cord glioma model

Oxidative stress is exerted by reactive oxygen species (ROS) that accumulate due to an imbalance between ROS generation and elimination, which impacts cellular metabolism and consequently tumorigenesis in the tumor microenvironment. Recently, our group has developed a spinal cord glioma (SCG) model in Göttingen minipigs. However, the mechanism of how SCGs balance redox and thereby modulate cellular proliferation is unclear. Here, we demonstrated that the NRF2/NQO1 signaling, known to mediate oxidative stress, is upregulated in unresectable SCG cells infiltrating at the leading edge compared with the core cells. Moreover, pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, were significantly elevated in the edge SCG cells. Immunohistochemistry demonstrated positive staining for a higher Ki-67 proliferative index, GFAP, SOX2 and Olig2 in the edge cells compared to the core cells. The oxidative metabolic heterogeneity of immune and stromal cell subtypes among tumor samples was also explored. Hence, our study demonstrated the tumor microenvironment and involvement of the NRF2/NQO1 pathway for redox homeostasis in our minipig SCG model, which can be used to explore targets of the pre-clinical treatment investigations in SCG.

Citation Format: Kecheng Lei, Muhibullah S. Tora, Stewart G. Neill, Purva P. Nagarajan, Thais Federici, Peter Canoll, Nicholas M. Boulis. Oxidative stress triggers tumor edge progression of tumor microenvironment in the minipig spinal cord glioma model [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 1609.

Impact of systemic therapy regimen on survival of PCNSL

2070

Background: Primary CNS Lymphoma (PCNSL) is a rare and often fatal disease. Treatment includes multi-agent systemic therapy with a backbone of high-dose methotrexate (HD-MTX). Despite multiple drug and radiotherapy combinations for induction and consolidation treatment there remains no clear standard of care. The purpose of this analysis is to evaluate how varying treatment approaches impacted clinical outcomes at our institution. Methods: Data retrospectively collected for 95 consecutive patients with PCNSL pathologically confirmed from 2002 to 2021. Primary endpoint was OS with secondary endpoints of PFS and LC. Progression based on RANO criteria. Kaplan-Meier analyses, Log-rank test and Cox proportional hazard models used for time to event endpoints. MVA by backward selection applying an alpha of 0.2 for associations with 1st line chemo agents, number of cycles of HD-MTX (>6 or 0-5), size of enhancing tumor at presentation, CSF cytology, type of surgery (biopsy, STR, or GTR), and use of WBRT. Results: Most patients had KPS >70 (64.2%), were HIV negative (89.5%), and had no history of solid organ transplant (95.8%). Diagnosis was made by biopsy (73.7%) or resection (GTR 13.7%, STR 12.6%). 54.3% had <14 cc contrast-enhancing tumor volume (median 12.6 cc, range 0.5 - 67.8 cc) and 48.6% had single enhancing lesion. Of the 62 patients treated first line with at least 1 cycle of HD-MTX, 61.3% were treated with HD-MTX + Rituximab (R) and 33.9% with HD-MTX + R + temozolomide (TMZ). With or after induction HD-MTX, 1-3 patients received one or a combination of cytarabine, thiotepa, procarbazine, vincristine, carmustine, or ASCT. Of the 60 patients with evaluable CSF, 30.0% had positive cytology. IT chemotherapy (ITc) was administered to 12 patients (5 with + cytology, 4 with - cytology, 3 with unknown cytology). WBRT for consolidation after chemotherapy used for 3 patients and as monotherapy for 9 patients. 2-year OS and PFS rate was 50.1% (95% CI 38.6%-60.5%) and 38.5% (95% CI 27.9%-49.0%). On MVA, > 6 cycles of MTX was associated with superior OS, PFS, and LC. For patients receiving any chemotherapy, addition of R was associated with inferior OS while ITc was associated with improved OS, PFS, and LC (Table). There was no OS association on MVA with TMZ, GTR, consolidation WBRT, or size or number of initial lesions (p>0.05). Conclusions: Completion of induction HD-MTX and use of ITc was associated with better outcomes in this population. Incorporation of R into 1st line therapy was associated with worse OS. Survival remained poor throughout the study period, underscoring importance of further innovation. [Table: see text]

Distinct phenotypic states and spatial distribution of CD8+ T cell clonotypes in human brain metastases

Metastatic disease in the brain is difficult to control and predicts poor prognosis. Here, we analyze human brain metastases and demonstrate their robust infiltration by CD8⁺ T cell subsets with distinct antigen specificities, phenotypic states, and spatial localization within the tumor microenvironment. Brain metastases are densely infiltrated by T cells; the majority of infiltrating CD8⁺ T cells express PD-1. Single-cell RNA sequencing shows significant clonal overlap between proliferating and exhausted CD8⁺ T cells, but these subsets have minimal clonal overlap with circulating and other tumor-infiltrating CD8⁺ T cells, including bystander CD8⁺ T cells specific for microbial antigens. Using spatial transcriptomics and spatial T cell receptor (TCR) sequencing, we show these clonally unrelated, phenotypically distinct CD8⁺ T cell populations occupy discrete niches within the brain metastasis tumor microenvironment. Together, our work identifies signaling pathways within CD8⁺ T cells and in their surrounding environment that may be targeted for immunotherapy of brain metastases.

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Human brain metastases (BrMs) are well infiltrated by CD8⁺ T cells

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Exhausted CD8⁺ T cells in BrMs have little TCR overlap with other infiltrating cells

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Bystander CD8⁺ T cells inhabit BrMs and adopt a resident progenitor-like phenotype

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Spatial TCR sequencing shows CD8⁺ T cell localization is linked to phenotypic state

Acanthamoeba castellanii encephalitis in a patient with AIDS: a case report and literature review

Amoebic encephalitis is a rare cause of CNS infection for which mortality exceeds 90%. We present the case of a 27-year-old man with AIDS who presented to a hospital in Atlanta (Georgia, USA) with tonic-clonic seizures and headache. His clinical condition deteriorated over several days. Brain biopsy revealed lymphohistiocytic inflammation and necrosis with trophozoites and encysted forms of amoebae. Immunohistochemical and PCR testing confirmed Acanthamoeba castellanii encephalitis, typically described as granulomatous amoebic encephalitis (GAE). No proven therapy for GAE is available, although both surgical and multiagent antimicrobial treatment strategies are often used. Most recently, these include the antileishmanial agent miltefosine. Here we review all cases of GAE due to Acanthamoeba spp in people with HIV/AIDS identified in the literature and reported to the Centers for Disease Control and Prevention. We describe this case as a reminder to the clinician to consider protozoal infections, especially free-living amoeba, in the immunocompromised host with a CNS infection refractory to traditional antimicrobial therapy.

Lentiviral-Induced Spinal Cord Gliomas in Rat Model

Intramedullary spinal cord tumors are a rare and understudied cancer with poor treatment options and prognosis. Our prior study used a combination of PDGF-B, HRAS, and p53 knockdown to induce the development of high-grade glioma in the spinal cords of minipigs. In this study, we evaluate the ability of each vector alone and combinations of vectors to produce high-grade spinal cord gliomas. Eight groups of rats (n = 8/group) underwent thoracolumbar laminectomy and injection of lentiviral vector in the lateral white matter of the spinal cord. Each group received a different combination of lentiviral vectors expressing PDGF-B, a constitutively active HRAS mutant, or shRNA targeting p53, or a control vector. All animals were monitored once per week for clinical deficits for 98 days. Tissues were harvested and analyzed using hematoxylin and eosin (H&E) and immunohistochemical (IHC) staining. Rats injected with PDGF-B+HRAS+sh-p53 (triple cocktail) exhibited statistically significant declines in all behavioral measures (Basso Beattie Bresnahan scoring, Tarlov scoring, weight, and survival rate) over time when compared to the control. Histologically, all groups except the control and those injected with sh-p53 displayed the development of tumors at the injection site, although there were differences in the rate of tumor growth and the histopathological features of the lesions between groups. Examination of immunohistochemistry revealed rats receiving triple cocktail displayed the largest and most significant increase in the Ki67 proliferation index and GFAP positivity than any other group. PDGF-B+HRAS also displayed a significant increase in the Ki67 proliferation index. Rats receiving PDGF-B alone and PDGF-B+ sh-p53 displayed more a significant increase in SOX2-positive staining than in any other group. We found that different vector combinations produced differing high-grade glioma models in rodents. The combination of all three vectors produced a model of high-grade glioma more efficiently and aggressively with respect to behavioral, physiological, and histological characteristics than the rest of the vector combinations. Thus, the present rat model of spinal cord glioma may potentially be used to evaluate therapeutic strategies in the future.

Functioning Crooke Cell Adenomas: Case Series and Literature Review

BACKGROUND

Crooke cell adenomas (CCA) are rare potentially aggressive pituitary adenomas. Data regarding prevalence and clinical course is sparse.

METHODS

Methods consisted of a retrospective review of 59 consecutive functioning corticotroph adenomas (FCA) operated between October 2017-November 2020, and a literature review of CCA publications since 1991.

RESULTS

The prevalence of CCA among FCA at our institution was 8.5% (5/59). In the 4 other surgical cases series, prevalence of CCA ranged between 0%-6.8%. Our patients, 4 women and 1 man, mean age 46±11 years, presented with hypercortisolism (3/5), vision loss (1/5) and incidentally (1/5). All patients had elevated ACTH (151±54 pg/ml) and urinary free cortisol (830±796.5 μg/day) levels. Radiologically, 3 tumors were macroadenomas and 2 had cavernous sinus invasion. All patients achieved biochemical remission at 3 months postoperatively. One patient with a giant pituitary adenoma underwent fractionated radiation for residual tumor. During follow-up (range: 3.1-31.0 months), no patients had evidence of radiological or biochemical recurrence. The literature review (3 case series) and 21 case reports identified 22 FCA with outcome data. Additional treatments included reoperation (50%), radiation (59%), bilateral adrenalectomy (23%) and Temozolomide (36%).

CONCLUSION

We report a higher CCA prevalence among functioning ACTH-adenomas after the implementation of 2017 WHO classification. In our series and the literature, most CCAs were macroadenomas with high ACTH levels. Postoperative outcomes were excellent in our series, while some cases from the literature were refractory to standard treatments. Larger clinical and molecular studies are needed to identify patients at risk.

The genomic profiling and MAMLD1 expression in human and canines with Cushing's disease

BACKGROUND

Cushing's disease (CD) is defined as hypercortisolemia caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (corticotroph PA) that afflicts humans and dogs. In order to map common aberrant genomic features of CD between humans and dogs, we performed genomic sequencing and immunostaining on corticotroph PA.

METHODS

For inclusion, humans and dog were diagnosed with CD. Whole exome sequencing (WES) was conducted on 6 human corticotroph PA. Transcriptome RNA-Seq was performed on 6 human and 7 dog corticotroph PA. Immunohistochemistry (IHC) was complete on 31 human corticotroph PA. Corticotroph PA were compared with normal tissue and between species analysis were also performed.

RESULTS

Eight genes (MAMLD1, MNX1, RASEF, TBX19, BIRC5, TK1, GLDC, FAM131B) were significantly (P < 0.05) overexpressed across human and canine corticotroph PA. IHC revealed MAMLD1 to be positively (3+) expressed in the nucleus of ACTH-secreting tumor cells of human corticotroph PA (22/31, 70.9%), but absent in healthy human pituitary glands.

CONCLUSIONS

In this small exploratory cohort, we provide the first preliminary insights into profiling the genomic characterizations of human and dog corticotroph PA with respect to MAMLD1 overexpression, a finding of potential direct impact to CD microadenoma diagnosis. Our study also offers a rationale for potential use of the canine model in development of precision therapeutics.

MRI Imaging Characteristics of Glioblastoma with Concurrent Gain of Chromosomes 19 and 20

Glioblastoma (GBM) is the most common and deadly primary brain tumor in adults. Some of the genetic variations identified thus far, such as IDH mutation and MGMT promotor methylation, have implications for survival and response to therapy. A recent analysis of long-term GBM survivors showed that concurrent gain of chromosomes 19 and 20 (19/20 co-gain) is a positive prognostic factor that is independent of IDH mutation status. In this study, we retrospectively identified 18 patients with 19/20 co-gain and compared their imaging features to a control cohort without 19/20 co-gain. Imaging features such as tumor location, size, pial invasion, and ependymal extension were examined manually. When compared without further genetic subclassification, both groups showed similar imaging features except for rates of pial invasion. When each group was subclassified by MGMT promotor methylation status however, the two groups showed different imaging features in a number of additional ways including tumor location, size, and ependymal extension. Our results indicate that different permutations of various genetic mutations that coexist in GBM may interact in unpredictable ways to affect imaging appearance, and that imaging prognostication may be better approached in the context of the global genomic profile rather than individual genetic alterations.

Gene expression signature to predict radiation response in lower-grade gliomas

2019

Background: Standard of care for lower-grade glioma (LGG) is maximal safe resection and risk-adaptive adjuvant therapy. While patients who benefit the most from adjuvant chemotherapy have been elucidated in prospective randomized studies, comparable insights for adjuvant radiotherapy (RT) are lacking. We sought to identify and validate patterns of gene expression that are associated with differential outcomes among LGG patients treated by RT from two large genomics databases. Methods: Patients from The Cancer Genome Atlas (TCGA) with LGG (WHO grade II–III gliomas) treated by surgery and adjuvant RT were randomized 1:1 to a training set or an internal validation set. Using patients in the training set, association between gene expression from resected tumor and progression-free survival (PFS) as well as overall survival (OS) was evaluated with adjustment for clinicopathologic covariates. A genomic risk score (GRS) was then constructed from the expression levels of top genes also screened for involvement in glioma carcinogenesis. The prognostic value of GRS was subsequently validated in the internal validation set of TCGA and a second distinct database, compiled by the Chinese Glioma Genome Association (CGGA). Results: From TCGA, 289 patients with LGG received adjuvant RT alone (38 grade II, 30 grade III) or chemoradiotherapy (CRT) (51 grade II, 170 grade III) between 2009 and 2015. From CGGA, 178 patients with LGG received adjuvant RT alone (40 grade II, 13 grade III) or CRT (41 grade II, 84 grade III) between 2004 and 2016. The genes comprising GRS are MAP3K15, MAPK10, CCL3, CCL4, and ADAMTS1, involved in MAP kinase activity, T cell chemotaxis, and cell cycle transition. High GRS, defined as having a GRS in the top third, was significantly associated with worse outcomes independent of age, sex, glioma histology, WHO grade, IDH mutation, 1p/19q co-deletion, and chemotherapy status in the training set (OS HR 2.74, P < 0.001; PFS HR 1.61, P = 0.014). These findings were further validated in the internal validation set (OS HR 1.84, P = 0.015; PFS HR 1.58, P = 0.027) and again in the CGGA external validation set (OS HR 1.72, P = 0.001). Association between GRS and outcomes was observed only among patients who received RT (RT alone or CRT), in both TCGA and CGGA. Conclusions: This study successfully identified an expression signature of five genes that stratified outcomes among LGG patients who received adjuvant RT, with two rounds of validation leveraging independent genomics databases. Expression levels of the highlighted genes were associated with survival only among patients whose treatments included RT, but not among those with omission of RT, suggesting that expression of these genes may be predictive of radiation treatment response. While additional prospective studies are warranted, interrogation of these genes to determine high/low GRS may be considered in the multidisciplinary management of LGGs.

Comparatıve assessment of thermal ınjury ınduced by bıpolar electrocautery systems ın a porcıne model

Background

Bipolar electrocautery systems used during neurosurgical procedures have been shown to induce thermal injury to surrounding tissue. The goal of this study was to compare the thermal injury induced by two different systems commonly used in neurosurgical procedures (Silverglide by Stryker Corporation and SpetzlerMalis by Codman Neuro), with that of a newly introduced device (TRIOwand by NICO Corporation).

Methods

A farm swine underwent craniectomy and durotomy with subsequent exposure of cortical brain tissue. Electrocoagulation for the duration of 3 s was conducted with three different bipolar systems under comparable power settings. The maximal depth of thermal injury and mean area of injury in Hematoxylin and Eosin stained slides were quantified using Image J. The tissues were evaluated for vacuolization and ischemic damage. One-way ANOVA followed by post hoc Tukey test was utilized for statistical analysis. Alpha level was set at 0.05.

Results

TRIOwand lesions showed less depth of injury when compared to both Spetzler-Malis (P < 0.001) and Silverglide lesions (P = 0.048). Silverglide lesions showed significantly less depth of injury when compared to SpetzlerMalis lesions (P < 0.001). The injury area induced by the TRIOwand was significantly less than that of Spetzler-Malis (P < 0.001) and Silverglide systems (P < 0.001). Ischemic changes and vacuolization were seen in all three groups.

Conclusion

Thermal damage is induced to varying extents by all bipolar systems. In this porcine model and under the conditions tested, bipolar cauterization with the TRIOwand resulted in less depth and decreased mean area of injury. Further studies are needed to characterize the injury caused by different bipolar systems with other settings and under surgical conditions in humans.

Co-Occurrence Conundrum: Brain Metastases from Lung Adenocarcinoma, Radiation Necrosis, and Gliosarcoma

Non-small cell lung cancer (NSCLC) commonly presents with metastasis to the brain. When brain metastases are treated with stereotactic radiosurgery (SRS), longitudinal imaging to monitor treatment response may identify radiation necrosis, metastasis progression, and/or another primary brain malignancy. A 60-year-old female with metastatic NSCLC involving the brain underwent treatment with systemic therapy and SRS. While some brain metastases resolved, two remaining sites evolved to resemble radiation necrosis on magnetic resonance imaging and spectroscopy. One of those sites was later confirmed to be radiation necrosis after receding with steroids and bevacizumab. The other lesion continued to enlarge and was then surgically resected, pathologically proven to be a gliosarcoma. When scan findings diverge among multiple treated disease sites, imaging should be cautiously interpreted in conjunction with clinical information as well as early surgical consultation for biopsy consideration, especially when there is suspicion of unusual or superimposed pathologies.

YAP/TAZ Transcriptional Coactivators Create Therapeutic Vulnerability to Verteporfin in EGFR-mutant Glioblastoma

PURPOSE

Glioblastomas (GBMs), neoplasms derived from glia and neuroglial progenitor cells, are the most common and lethal malignant primary brain tumors diagnosed in adults, with a median survival of 14 months. GBM tumorigenicity is often driven by genetic aberrations in receptor tyrosine kinases, such as amplification and mutation of EGFR.

EXPERIMENTAL DESIGN

Using a Drosophila glioma model and human patient-derived GBM stem cells and xenograft models, we genetically and pharmacologically tested whether the YAP and TAZ transcription coactivators, effectors of the Hippo pathway that promote gene expression via TEA domain (TEAD) cofactors, are key drivers of GBM tumorigenicity downstream of oncogenic EGFR signaling.

RESULTS

YAP and TAZ are highly expressed in EGFR-amplified/mutant human GBMs, and their knockdown in EGFR-amplified/mutant GBM cells inhibited proliferation and elicited apoptosis. Our results indicate that YAP/TAZ-TEAD directly regulates transcription of SOX2, C-MYC, and EGFR itself to create a feedforward loop to drive survival and proliferation of human GBM cells. Moreover, the benzoporphyrin derivative verteporfin, a disruptor of YAP/TAZ-TEAD-mediated transcription, preferentially induced apoptosis of cultured patient-derived EGFR-amplified/mutant GBM cells, suppressed expression of YAP/TAZ transcriptional targets, including EGFR, and conferred significant survival benefit in an orthotopic xenograft GBM model. Our efforts led us to design and initiate a phase 0 clinical trial of Visudyne, an FDA-approved liposomal formulation of verteporfin, where we used intraoperative fluorescence to observe verteporfin uptake into tumor cells in GBM tumors in human patients.

CONCLUSIONS

Together, our data suggest that verteporfin is a promising therapeutic agent for EGFR-amplified and -mutant GBM.

Genomic copy number variation correlates with survival outcomes in WHO grade IV glioma

Allele-specific copy number analysis of tumors (ASCAT) assesses copy number variations (CNV) while accounting for aberrant cell fraction and tumor ploidy. We evaluated if ASCAT-assessed CNV are associated with survival outcomes in 56 patients with WHO grade IV gliomas. Tumor data analyzed by Affymetrix OncoScan FFPE Assay yielded the log ratio (R) and B-allele frequency (BAF). Input into ASCAT quantified CNV using the segmentation function to measure copy number inflection points throughout the genome. Quantified CNV was reported as log R and BAF segment counts. Results were confirmed on The Cancer Genome Atlas (TCGA) glioblastoma dataset. 25 (44.6%) patients had MGMT hyper-methylated tumors, 6 (10.7%) were IDH1 mutated. Median follow-up was 36.4 months. Higher log R segment counts were associate with longer progression-free survival (PFS) [hazard ratio (HR) 0.32, p < 0.001], and overall survival (OS) [HR 0.45, p = 0.01], and was an independent predictor of PFS and OS on multivariable analysis. Higher BAF segment counts were linked to longer PFS (HR 0.49, p = 0.022) and OS (HR 0.49, p = 0.052). In the TCGA confirmation cohort, longer 12-month OS was seen in patients with higher BAF segment counts (62.3% vs. 51.9%, p = 0.0129) and higher log R (63.6% vs. 55.2%, p = 0.0696). Genomic CNV may be a novel prognostic biomarker for WHO grade IV glioma patient outcomes.

Copy number assessment in the genomic analysis of CNS neoplasia: An evidence-based review from the cancer genomics consortium (CGC) working group on primary CNS tumors

The period from the 1990s to the 2010s has witnessed a burgeoning sea change in the practice of surgical neuropathology due to the incorporation of genomic data into the assessment of a range of central nervous system (CNS) neoplasms. This change has since matured into the adoption of genomic information into the definition of several World Health Organization (WHO)-established diagnostic entities. The data needed to accomplish the modern diagnosis of CNS neoplasia includes DNA copy number aberrations that may be assessed through a variety of mechanisms. Through a review of the relevant literature and professional practice guidelines, here we provide a condensed and scored overview of the most critical DNA copy number aberrations to assess for a selection of primary CNS neoplasms.

Abstract 3721: Improved fitting of HRMAS NMR spectra for ex vivo metabolomic analysis of glioma tissue

Gliomas are aggressive brain tumors with high rates of treatment resistance and low survival rates. High-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy can quantify metabolite concentrations in glioma tissue, but most analysis techniques require manual peak selection and integration that prevents accurate and reliable quantitation of overlapping peaks and large macromolecule baselines. Our goal was to compare the effectiveness of operator-independent LCModel analysis of glioma spectra acquired from free induction decay (FID) and Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences.

HRMAS NMR spectra were acquired using FID and CPMG sequences from 14 histologically-confirmed glioma tissue samples (WHO grade II (n=5), III (n=5), and IV (n=4)) collected during surgical resection from human brain tumor patients. Metabolite concentration ratios and Cramer-Rao lower bounds (CRLBs) were estimated using LCModel. Metabolite CRLBs were compared using a paired two sample t-test. Differences in concentrations as a function of WHO grade were determined with ANOVA and Tukey-Kramer post-hoc tests. Significance was determined by p&lt;.05.

Metabolite CRLBs for lactate and myo-inositol were significantly lower for CPMG compared to FID spectra (p&lt;.05). Most metabolites could be quantified with LCModel from spectra acquired with CPMG where many metabolites acquired with the FID sequence were not detected. For example, lactate was quantifiable from 3 of the spectra acquired with FID compared to 12 spectra with CPMG. The use of the CPMG sequence reduces quantification errors by eliminating confounding baseline signals. LCModel facilitates improved separation of overlapping resonances compared to manual peak integration, supporting the use of operator-independent methods for metabolic spectral analysis.

Comparison of metabolite concentrations as a function of WHO grade revealed significant differences in lactate and glutamine plus glutamate normalized to creatine (p&lt;.05). 2-hydroxyglutarate (2-HG) was also detected in 9 out of 13 isocitrate dehydrogenase (IDH)-mutated samples using both sequences. IDH-mutated tissue should produce 2-HG; however, these results are promising as 2-HG can be difficult to quantify in 1D NMR due to spectral overlap.

In conclusion, LCModel can reliably quantify HRMAS spectra acquired with the CPMG sequence but is less reliable with the FID sequence. Increases in lactate and glutamine plus glutamate concentrations as a function of tumor grade were consistent with previous results using HRMAS for glioma metabolic analysis, and 2-HG was detected in 1D HRMAS spectra acquired with both sequences. We expect that improved spectral fitting will contribute to future NMR-based metabolomics studies in glioma.

Note: This abstract was not presented at the meeting.

Citation Format: Selin Ekici, Ren Geryak, Stewart G. Neill, Hui-Kuo Shu, Candace C. Fleischer. Improved fitting of HRMAS NMR spectra for ex vivo metabolomic analysis of glioma tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3721.

The Intriguing Case of a Double Pituitary Adenoma

BACKGROUND

When distinct pituitary hypersecretory manifestations coexist, the differential diagnosis includes plurihormonal or double pituitary adenomas. We describe a rare case of hypercortisolemia and hyperprolactinemia caused by 2 noncontiguous adenomas that required 2 surgeries.

CASE DESCRIPTION

A 37-year-old woman presented with 6 months of weight gain, amenorrhea, joint pain, leg swelling, and skin changes. She received prednisone for possible systemic lupus erythematosus. Four months later, she presented with headaches and new-onset diabetes with glucose >1000 mg/dL. Work-up revealed a right-sided 1.1-cm pituitary adenoma and prolactin level of 152.9 ng/mL (normal: 3-27 ng/mL). She was advised to stop the prednisone, start bromocriptine, and see a pituitary specialist. Examination revealed centripetal obesity, supraclavicular and dorsocervical fat pads, violaceous wide striae, bilateral leg edema, and galactorrhea. Workup confirmed adrenocorticotrophic hormone-dependent Cushing syndrome, with a central-to-peripheral gradient on inferior petrosal sinus sampling bilaterally. Transsphenoidal adenenomectomy yielded an adenoma diffusely positive for prolactin. Postoperatively prolactin normalized, hypercortisolemia persisted, and magnetic resonance imaging findings raised suspicion for a 2-mm microadenoma. The patient underwent a second operation when an adrenocorticotrophic hormone-positive adenoma was identified. After 4 years, both hypersecretory syndromes remain in biochemical remission.

CONCLUSIONS

A complete clinical and biochemical evaluation is necessary in patients with pituitary adenomas. Repeat surgery may be necessary for noncontiguous double adenomas.

Safety and effectiveness of stereotactic laser ablation for epileptogenic cerebral cavernous malformations

OBJECTIVE

Magnetic resonance (MR) thermography-guided laser interstitial thermal therapy, or stereotactic laser ablation (SLA), is a minimally invasive alternative to open surgery for focal epilepsy caused by cerebral cavernous malformations (CCMs). We examined the safety and effectiveness of SLA of epileptogenic CCMs.

METHODS

We retrospectively analyzed 19 consecutive patients who presented with focal seizures associated with a CCM. Each patient underwent SLA of the CCM and adjacent cortex followed by standard clinical and imaging follow-up.

RESULTS

All but one patient had chronic medically refractory epilepsy (median duration 8 years, range 0.5-52 years). Lesions were located in the temporal (13), frontal (five), and parietal (one) lobes. CCMs induced magnetic susceptibility artifacts during thermometry, but perilesional cortex was easily visualized. Fourteen of 17 patients (82%) with >12 months of follow-up achieved Engel class I outcomes, of which 10 (59%) were Engel class IA. Two patients who were not seizure-free from SLA alone became so following intracranial electrode-guided open resection. Delayed postsurgical imaging validated CCM involution (median 83% volume reduction) and ablation of surrounding cortex. Histopathologic examination of one previously ablated CCM following open surgery confirmed obliteration. SLA caused no detectable hemorrhages. Two symptomatic neurologic deficits (visual and motor) were predictable, and neither was permanently disabling.

SIGNIFICANCE

In a consecutive retrospective series, MR thermography-guided SLA was an effective alternative to open surgery for epileptogenic CCM. The approach was free of hemorrhagic complications, and clinically significant neurologic deficits were predictable. SLA presents no barrier to subsequent open surgery when needed.

Meningioma With Tyrosine-Rich Crystalloids: A Case Report and Review of the Literature

We report a case of fibrous meningioma with tyrosine-rich crystalloid in the frontal lobe of a middle-aged woman. The patient presented with a history of several years of worsening headaches and blurry vision, which progressed to include syncopal episodes and right-sided weakness. Imaging demonstrated a dural-based extra-axial mass arising from the right orbital roof and extending superiorly along the right frontal convexity causing right-to-left midline shift. The patient underwent a craniotomy and operative resection. Tumor architecture and cytology was similar to that of a Schwannian neoplasm, with spindled cells arranged in a fascicular architecture and displaying focal nuclear palisading. Immunohistochemical stains confirmed a diagnosis of fibrous meningioma. Light microscopy demonstrated extracellular deposits of eosinophilic crystalline material parallel to the spindled tumor cells, reminiscent of "tyrosine-rich" crystals described in salivary gland neoplasms. This is the third meningioma featuring tyrosine-rich crystalloid reported in the literature; we also summarize the previous 2 reports.

Molecular impact of selective NFKB1 and NFKB2 signaling on DLBCL phenotype

Diffuse large B-cell lymphoma (DLBCL) has been categorized into two molecular subtypes that have prognostic significance, namely germinal center B-cell like (GCB) and activated B-cell like (ABC). Although ABC-DLBCL has been associated with NF-κB activation, the relationships between activation of specific NF-κB signals and DLBCL phenotype remain unclear. Application of novel gene expression classifiers identified two new DLBCL categories characterized by selective p100 (NF-κB2) and p105 (NF-κB1) signaling. Interestingly, our molecular studies showed that p105 signaling is predominantly associated with GCB subtype and histone mutations. Conversely, most tumors with p100 signaling displayed ABC phenotype and harbored ABC-associated mutations in genes such as MYD88 and PIM1. In vitro, MYD88 L265P mutation promoted p100 signaling through TAK1/IKKα and GSK3/Fbxw7a pathways, suggesting a novel role for this protein as an upstream regulator of p100. p100 signaling was engaged during activation of normal B cells, suggesting p100's role in ABC phenotype development. Additionally, silencing p100 in ABC-DLBCL cells resulted in a GCB-like phenotype, with suppression of Blimp, IRF4 and XBP1 and upregulation of BCL6, whereas introduction of p52 or p100 into GC cells resulted in differentiation toward an ABC-like phenotype. Together, these findings identify specific roles for p100 and p105 signaling in defining DLBCL molecular subtypes and posit MYD88/p100 signaling as a regulator for B-cell activation.

Genomic Analysis in the Practice of Surgical Neuropathology: The Emory Experience

The evaluation of central nervous system tumors increasingly relies on molecular genetic methods to aid in classification, offer prognostic information, and predict response to therapy. Available assays make it possible to assess genetic losses, amplifications, translocations, mutations, or the expression levels of specific gene transcripts or proteins. Current molecular diagnostics frequently use a panel-based approach and whole genome analysis, and generally rely either on DNA sequencing or on hybridization-based methodologies, such as those used in cytogenomic microarrays. In some cases, immunohistochemistry can be used as a surrogate for genetic analysis when the mutation of interest consistently results in overexpression or underexpression of a known protein product. In surgical neuropathology practice, the diagnostic workup of diffuse gliomas, medulloblastomas, low-grade circumscribed gliomas, as well as other diseases, now routinely incorporates the results of genomic studies. Here we summarize our institution's current approach to diagnostic surgical neuropathology, using these contemporary molecular diagnostic applications.

Abstract 3607: An evaluation of NGS to identify gene fusions using RNA from FFPE solid tumor samples

Gene fusions have long been considered strong drivers of cellular transformation, making the accurate and precise assessment of these variants a necessity for any tumor profiling assay. Recent studies have indicated the utility of next-generation sequencing (NGS) for tumor profiling due to increasing data output and decreasing costs of the technology. Unfortunately, because a critical facet of NGS is the evaluation of short DNA fragments, sufficiently covering all possible breakpoint regions (many of which are intronic) has proven difficult and costly. Recent studies have indicated that NGS may prove better at detecting gene fusions using RNA instead of DNA, given the higher probability of breakpoint-spanning reads. This allows for de-novo discovery of fusion partners without knowing the precise breakpoint and guarantees expression of the fusion transcript. To that end, Illumina is developing a novel method for simultaneous library preparation from low input amounts of degraded DNA and RNA from a single FFPE tumor sample. With a turnaround time from nucleic acid to data of less than 4 days, this enrichment-based assay surveys 170 genes for single nucleotide variants and small indels, 57 genes for gene amplifications, 55 genes for fusions and four genes for splice variants. To determine the limit of detection for gene fusions, a panel of different synthetic RNA transcripts were prepared in vitro, pooled at equal molar amounts, and spiked into 20ng of cell line RNA (MCF-7). Fusions were detected over several orders of magnitude down to 1×10-8 picomoles, equivalent to 3 to 15 fusion transcripts per cell. In addition, a similar range of fusion detection was observed when RNA from two different cell lines were mixed, as when RNA from a cell line with high expression of an FGFR2-COL14A1 fusion was mixed in proportional amounts with RNA from a different cell line where FGFR2 is minimally expressed. Importantly, our method allowed for fusion detection from as little as 100 picograms of cell line RNA. We then tested our new method on previously characterized FFPE solid tumor samples harboring known gene rearrangements identified by FISH and other methods. Not only was the NGS method able to detect the majority of previously characterized variants, including EML4-ALK and SDC4-ROS1, it also identified the gene fusions and their uncharacterized fusions partners by combining the non-targeted sequence information gained from using an enrichment-based assay with novel fusion calling algorithms. From this information, we were able to glean new insights into the structure of the rearrangements and how the gene fusions may be involved in tumorigenesis. These results indicate that NGS can identify fusions from the low amounts of degraded RNA from solid tumor samples, identify fusion partners not uncovered by current technologies, and further emphasizes the advantage of NGS in solid tumor profiling.

Citation Format: Julianna Tdr Parks, Luo Byron, Brian Crain, Snedecor June, Zhao Chen, Tingting Du, Gabriel L. Sica, Taofee K. Owonikoko, Stewart G. Neill, Scott Newman, Debra F. Saxe, Jennifer S. LoCoco, Han-Yu Chuang, Charles Lin, Kathryn M. Stephens, Michael R. Rossi, Matthew C. Friedenberg. An evaluation of NGS to identify gene fusions using RNA from FFPE solid tumor samples. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3607.

A systematic pipeline for the objective comparison of whole-brain spectroscopic MRI with histology in biopsy specimens from grade III glioma

The diagnosis, prognosis, and management of patients with gliomas are largely dictated by the pathological analysis of tissue biopsied from a selected region within the lesion. However, the heterogeneous and infiltrative nature of gliomas make it difficult to identify the optimal region for biopsy with conventional magnetic resonance imaging (MRI). This is particularly true for low-grade gliomas, which are often nonenhancing tumors. To improve the management of patients with such tumors, neuro-oncology requires an imaging modality that can specifically identify a tumor's most anaplastic/aggressive region(s) for biopsy targeting. The addition of metabolic mapping using spectroscopic MRI (sMRI) to supplement conventional MRI could improve biopsy targeting and, ultimately, diagnostic accuracy. Here, we describe a pipeline for the integration of state-of-the-art, high-resolution, whole-brain 3-dimensional sMRI maps into a stereotactic neuronavigation system for guiding biopsies in gliomas with nonenhancing components. We also outline a machine-learning method for automated histological analysis that generates normalized, quantitative metrics describing tumor infiltration in immunohistochemically stained tissue specimens. As a proof of concept, we describe the combination of these 2 techniques in a small cohort of patients with grade 3 glioma. With this work, we aim to present a systematic pipeline to stimulate histopathological image validation of advanced MRI techniques, such as sMRI.

Whole-brain spectroscopic MRI biomarkers identify infiltrating margins in glioblastoma patients

BACKGROUND

The standard of care for glioblastoma (GBM) is maximal safe resection followed by radiation therapy with chemotherapy. Currently, contrast-enhanced MRI is used to define primary treatment volumes for surgery and radiation therapy. However, enhancement does not identify the tumor entirely, resulting in limited local control. Proton spectroscopic MRI (sMRI), a method reporting endogenous metabolism, may better define the tumor margin. Here, we develop a whole-brain sMRI pipeline and validate sMRI metrics with quantitative measures of tumor infiltration.

METHODS

Whole-brain sMRI metabolite maps were coregistered with surgical planning MRI and imported into a neuronavigation system to guide tissue sampling in GBM patients receiving 5-aminolevulinic acid fluorescence-guided surgery. Samples were collected from regions with metabolic abnormalities in a biopsy-like fashion before bulk resection. Tissue fluorescence was measured ex vivo using a hand-held spectrometer. Tissue samples were immunostained for Sox2 and analyzed to quantify the density of staining cells using a novel digital pathology image analysis tool. Correlations among sMRI markers, Sox2 density, and ex vivo fluorescence were evaluated.

RESULTS

Spectroscopic MRI biomarkers exhibit significant correlations with Sox2-positive cell density and ex vivo fluorescence. The choline to N-acetylaspartate ratio showed significant associations with each quantitative marker (Pearson's ρ = 0.82, P < .001 and ρ = 0.36, P < .0001, respectively). Clinically, sMRI metabolic abnormalities predated contrast enhancement at sites of tumor recurrence and exhibited an inverse relationship with progression-free survival.

CONCLUSIONS

As it identifies tumor infiltration and regions at high risk for recurrence, sMRI could complement conventional MRI to improve local control in GBM patients.