bluuebunny/crossref_metadata_2025 huggingface dataset:
BIOM-41. GENETIC MARKERS CORRELATED WITH PROGRESSION-FREE SURVIVAL TIMES IN GLIOBLASTOMA PATIENTS UNDERGOING TREATMENT WITH TUMOR TREATING FIELDS
Authors: Monson Caitlin , Tipps Megan , Jackson Kelsey , Tierney Meghan , Banerji Nilanjana , Trusheim John
Published: December 2020

INTRODUCTION

Despite advances in surgical approaches, followed by chemo-radiotherapy protocols, the overall prognosis for patients with glioblastoma remains poor. Clinical trials have demonstrated that the use of low intensity alternating electric fields, known as Tumor Treating Fields (TTFields), via the Optune™ device extends overall survival times when combined with standard chemotherapy. However, the response to TTFields varies across patients, and it is currently unclear why some patients show increased time to tumor progression with TTFields treatment while others do not. One possible answer lies in the biological diversity of the tumors themselves. Genetic alterations are known to impact survival times and chemotherapy sensitivity in glioblastoma, suggesting that certain markers may also predict responsiveness to TTFields. Here, we compare the genetic profile of primary glioblastoma tumors with progression times in patients receiving TTFields treatment.

METHODS

Patients with primary glioblastoma who chose treatment with the Optune™ device were prospectively enrolled and a sample from their primary tumor resection was sent for FoundationONE CDx™ testing. Genetic alteration results, including mutation burden and copy number alterations, were then compared with clinical data and tumor progression times.

RESULTS

Mutations and/or copy number changes in genes that regulate cell growth/proliferation, apoptosis, and interactions with DNA were among the most common alterations observed in our cohort. For patients that recurred within 12 months, we found a common pattern of alterations that includes CDKN2A/2B co-deletion, MTAP deletion, and PIK3 mutations. This pattern was not observed in patients that recurred after 12 months.

CONCLUSION

The identification of genetic markers that predict treatment responsiveness may help direct patients toward optimal treatment options. Ongoing work is aimed at expanding our sample size, correlating these genetic markers with overall patient survival, and determining if this pattern of expression is specifically related to TTFields treatment response.
BIOM-44. GENOMIC PREDICTORS OF ADVERSE EVENTS IN NEWLY DIAGNOSED IDH-WILDTYPE GLIOBLASTOMA
Authors: Jane Lim-Fat Mary , Rahman Rifaquat , Muzikansky Alona , Woodward Eleanor , Whorral Sydney , Allen Marie , Touat Mehdi , Iorgulescu Bryan , Youssef Gilbert , Chukwueke Ugonma , Mcfaline-Figueroa Jose , Nayak Lakshmi , Lee Eudocia , Reardon David , Huang Raymond , Beroukhim Rameen , Bi Wenya Linda , Ligon Keith , Wen Patrick
Published: December 2020

BACKGROUND

Adverse outcomes including lymphopenia, thromboembolism (VTE), pseudoprogression and seizures cause significant morbidity in glioblastoma (GBM) patients. The association between genomic biomarkers and adverse outcomes in IDH-wildtype (IDH-wt) GBM needs to be further validated.

METHODS

We identified 1,011 consecutive adult patients with histologically confirmed GBM with OncoPanel testing (capture-based next-generation sequencing of 447 cancer-associated genes) at Dana-Farber Cancer Institute from 2013–2019. IDH-mutant patients and those without consistent follow-up at DFCI were excluded. Seizure at presentation, lymphopenia (absolute lymphocyte count < 1.0x109/L) at the beginning and end of chemoradiation, VTE, radiographic pseudoprogression (< 6 months of RT end) and early progression (< 6 months since completing RT) were identified retrospectively as adverse events. Single nucleotide variants and indels of relevant genes (Tier 1 or 2 mutations) and copy number analysis were derived. Variables were compared using Wilcoxon rank-sum test or Fisher’s Exact test with p< 0.05 indicating statistical significance.

RESULTS

Among 557 patients included, 198/508 (39%) had MGMT-methylated GBMs. Seizure at presentation occurred in 176/542 (32%) and was more common in TP53- or RB1-mutant GBM. Pre-RT 83/338 (25%), but not post-RT lymphopenia (249/367, 68%), was associated with PIK3CA mutation. VTE was detected in 74/509 (15%) during follow-up and was associated with mutations in PIK3CA and POLE. Pseudoprogression was noted in 43/457 (9%) of patients and was not associated with MGMT status or genomic alterations. Early progressive disease occurred in 33% of patients and was associated with unmethylated MGMT, PIK3CA, STAG2 and PTPN11 mutations. Median overall survival for the entire cohort was 17.5 months.

CONCLUSION

PIK3CA mutations were associated with baseline lymphopenia, risk of VTE and early progression in this cohort. Genomic biomarkers may help identify patients at higher risk of select adverse events in IDH-wt GBM. This could benefit patients through tailoring of supportive care and prophylactic therapies.
BIOM-54. A RAPID GENOTYPING PANEL FOR SENSITIVE AND SPECIFIC SEGREGATION OF CNS PATHOLOGIES
Authors: Gupta Mihir , Burns Evan , Georgantas Nicholas , Thierauf Julia , Nayyar Naema , Burns Ryan , Velarde Jose , Brastianos Priscilla , Dietrich Jorg , Marble Hetal , Lennerz Jochen , Romero Javier , Tateishi Kensuke , Cahill Daniel , Shankar Ganesh
Published: December 2020

Primary central nervous system lymphoma (PCNSL) remains challenging to diagnose due to nonspecific clinical and radiologic features and low diagnostic yields of cerebrospinal fluid (CSF) studies. We sought to characterize the diagnostic approach of suspected PCNSL, in order to improve clinical workflow. We first reviewed 1,007 new brain lesions of unknown etiology that included PCNSL in the radiologic differential diagnosis. The most common final diagnoses included high-grade glioma (28.2%) and PCNSL (14.6%). Diagnostic biopsies were frequently performed for high-grade glioma (100%) and PCNSL (94.4%), while CSF was frequently sampled for PCNSL (78.7%). We next identified 159 patients with an established new diagnosis of PCNSL. CSF studies were non-diagnostic in 86.7% of cases, whereas biopsy was positive in 93%. However, intraoperative histopathology was inconclusive for PNCSL in 54.5%, likely contributing to 22% of patients undergoing surgical resection. These challenges resulted in 12 days median time to treatment initiation, and readmission for further workup or treatment initiation in 27% of patients. These results indicated the need for a rapid, sensitive and specific platform to segregate PCNSL and glioma using CSF and tissue samples. We developed a qPCR-based assay to genotype the MYD88 L265P hotspot mutation from CSF and plasma within 80 minutes of sample acquisition. Results were concordant with orthogonal DNA sequencing in extracts from 87 archived specimens, with detection limits of 490pg of input genomic DNA and 0.15% mutant allele frequency. When performed simultaneously with assays for TERT promoter, IDH1/2, H3F3A and BRAF point mutations, the resulting panel accurately segregated PCNSL and adult diffuse glioma molecular diagnoses in 87 archived specimens and 19 prospective liquid biopsies, including cases of lymphoma and glioma. We propose that inclusion of targeted analysis of these mutually exclusive recurrent molecular alterations characterizing gliomas and PCNSL will facilitate rapid, sensitive diagnosis from solid and liquid biopsies.
BIOM-56. THE INTEGRATION OF A LIQUID BIOPSY PROGRAM INTO THE CARE OF PEDIATRIC BRAIN TUMOR PATIENTS
Authors: Miller Alexandra , Szalontay Luca , Ahmad Hamza , Bouvier Nancy , Rodriguez-Sanchez Irene , Bale Tejus , Benayed Ryma , Arcila Maria , Donzelli Maria , Dunkel Ira , Gilheeney Stephen , Khakoo Yasmin , Kramer Kim , Sait Sameer Farouk , Souweidane Mark , Mellinghoff Ingo , Karajannis Matthias
Published: December 2020

Pediatric CNS tumors remain the leading cause of cancer-related death in children and adolescents. Safe sampling of tumor tissue for diagnostic purposes may be difficult if not impossible. Detection of minimal residual or recurrent disease prior to definitive clinical or radiographic progression may allow earlier initiation of novel therapies and ultimately improve overall survival. Given the rarity of serial sampling of tumor tissue, our understanding of molecular evolution in response to therapy remains limited. Recent technological advances have led to the development of “liquid biopsy” assays, which detect cell-free DNA (cfDNA) in blood, cerebrospinal fluid (CSF) or other bodily fluids. Here, we report our initial clinical experience with the recently established MSK Kids pediatric neuro-oncology liquid-biopsy program at Memorial Sloan Kettering Cancer Center (MSKCC) using MSK-IMPACT, which is clinically validated by the New York State Department of Health for CSF cell-free DNA (cfDNA)vprofiling. All CSF samples were collected as part of clinical care, and results reported to both clinicians and patients/families. Samples from 29 unique patients were sequenced. Histopathology included high-grade glioma (5); low-grade glioma (2); medulloblastoma (8); pineoblastoma (3); retinoblastoma (4); other (7). CSF cfDNA could be detected in 18/42 samples (43%) and 12/29 patients (34%). CSF cfDNA was more commonly detected in higher-grade, disseminated tumors such as high-grade glioma (60%), medulloblastoma (38%), and pineoblastoma (100%). Low-grade lesions without leptomeningeal involvement did not result in detectable CSF cfDNA shedding (86% were negative). In a subset of patients, MSK-IMPACT identified previously unrecognized molecular actionable targets (e.g. BRAF-KIAA1549 fusion); or the detection of “minimal residual disease” prior to the detection of tumor recurrence by conventional diagnostics, impacting clinical care decisions. Future directions include integration of CSF cfDNA into prospective clinical trials as a correlative biomarker.
BIOM-61. FUNCTIONAL DIAGNOSTIC TESTING OF LIVE-CELL DRUG RESPONSE USING 3D PATIENT DERIVED GLIOBLASTOMA SPHEROIDS ON THE INCUCYTE PLATFORM
Authors: Malinowski Seth , Touat Mehdi , Stockslager Max , Giglio Ross , Geduldig Jack , Sinai Claire , Pelton Kristine , Reardon David , Wen Patrick , Chow Kin Hoe , Manalis Scott , Ligon Keith
Published: December 2020

Three-dimensional patient derived cultures hold great potential for use as personalized functional diagnostics, enabling more accurate preclinical evaluations of drug treatments compared to conventional cell lines. Optical imaging of live cells allows for continuous, time lapsed measurements, and can provide drug response data based on rich phenotypic changes of cell cultures. However, current imaging techniques based on 2D microscopy evaluation aren’t readily adaptable to evaluate the drug response of intact spheroids, which may better represent the in vivo environment and retain critical cellular interactions within the tumor microenvironment. Using the IncuCyte live cell imaging platform, we successfully imaged a large cohort (n = 77) of patient derived glioblastoma spheroid cultures and evaluated whether changes in sphere volume could be used as a direct measure of treatment response. Improving on the default Incucyte analysis software, we developed an R data processing pipeline better suited for spheroid measurements, which quantified the heterogeneity in GBM baseline spheroid growth, and calculated a drug response score based on spheroid changes in response to DNA damaging agents (TMZ as an example). Compared to conventional viability measurements, this novel 3D drug response score was found to accurately identify both drug sensitive and resistant spheroids and showed robust concordance with genomic biomarkers of response (NGS and MGMT promoter methylation) and patient outcomes. Additionally, we coupled the 3D drug score with known genetic data to explore other key pathways and genes involved in TMZ response. We provide here novel analysis methods and public code (Github) to advance the use of IncuCyte spheroid measurements, and deconvolute 3D spheroid drug response into a quantifiable statistic. These methods are adaptable to freshly isolated patient cells for rapid evaluation of treatment response in GBM patients while remaining widely applicable to other cancers such as pancreatic, colon, and non-cancer organoids/spheroids with 3D growth.
CBIO-02. COMPREHENSIVE ANALYSIS OF MECHANISMS AND MOLECULAR TARGETS FOR BREAST CANCER LEPTOMENINGEAL METASTASIS
Authors: Kijima Noriyuki , Achiha Takamune , Nakagawa Tomoyoshi , Hirayama Ryuichi , Kinoshita Manabu , Kagawa Naoki , Kishima Haruhiko
Published: December 2020

Leptomeningeal metastasis from solid cancer is a devastating state for cancer patients. Leptomeningeal metastasis is diagnosed either by cerebrospinal fluid cytology and/or magnetic resonance imaging (MRI). However, it remains unclear as to whether tumor cells attached to leptomeninges are the same from floating tumor cells in cerebrospinal fluid (CSF). In this study, we aim to analyze the differences between tumor cells attached to leptomeninges and floating cells in CSF by xenograft models. We used breast cancer cell line, MDA-MB-231, labelled with green fluorescent protein (GFP) and luciferase. We injected those cells into right lateral ventricle of NOD/Shi-scid IL2Rγ KO mice. When the mice got any signs of tumor, we dissected spinal cord and got CSF from mice. We sorted tumor cells by flow cytometry and extracted RNA from the sorted tumor cells from spinal cord and CSF, respectively. We analyzed transcriptome differences between tumor cells from spinal cord and CSF by RNA sequencing. We found that extracellular matrix related proteins were highly upregulated while cell growth related proteins were downregulated in tumor cells from spinal cord compared with those from CSF. These results suggest that tumor cells attached to leptomeninges have different transcriptome profiles from floating tumor cells in CSF and extracellular matrix related proteins could be therapeutic targets for breast cancer leptomeningeal metastasis.
CBIO-08. ASTROCYTE SENESCENCE CONTRIBUTES TO SEX DIFFERENCES IN GLIOBLASTOMA INCIDENCE AND OUTCOME
Authors: Broestl Lauren , Rhee Gina , Grandison Lucia , Sponagel Jasmin , Kfoury Najla , Hill Cameron , Rubin Joshua
Published: December 2020

Sex differences in incidence and outcome are consistently observed in cancer, including in the most common malignant brain tumor – glioblastoma (GBM). Women are less likely to develop GBM and have a survival advantage compared to men. Previous research from our lab identified the proteins Rb, p16, and p21 as key mediators of female protection against cellular transformation. Strikingly, these proteins are all primary components of the senescence response, a potent cell-intrinsic anti-cancer mechanism that results in permanent cell cycle arrest, preventing proliferation of damaged cells. We hypothesized that sex differences in GBM incidence and outcome are mediated by differences in senescence induction after DNA damage in male and female cells. Using both wildtype astrocytes and a GBM model, we found that females have a lower threshold for senescence induction in response to oxidative stress, telomere shortening, and treatment with chemotherapy or radiation. Following irradiation, female GBM model cells had higher levels of p21 expression, and p21 levels correlated with the percentage of senescent cells. Knocking out p21 eliminated sex differences in the senescence response following irradiation. Achieving a better understanding of mechanisms of senescence and how they differ in male and female cells could advance development of senescence-directed therapies and potentially improve treatment for brain tumors.
CBIO-10. REDUCED IRON EXPORT FUNCTIONS IN A CELL INTRINSIC MANNER TO DRIVE GLIOBLASTOMA GROWTH
Authors: Troike Katie , Mulkearns-Hubert Erin , Silver Daniel , Connor James , Lathia Justin
Published: December 2020

Glioblastoma (GBM), the most common primary malignant brain tumor in adults, is characterized by invasive growth and poor prognosis. Iron is a critical regulator of many cellular processes, and GBM tumor cells have been shown to modulate expression of iron-associated proteins to enhance iron uptake from the surrounding microenvironment, driving tumor initiation and growth. While iron uptake has been the central focus of previous investigations, additional mechanisms of iron regulation, such as compensatory iron efflux, have not been explored in the context of GBM. The hemochromatosis (HFE) gene encodes a transmembrane glycoprotein that aids in iron homeostasis by limiting cellular iron release, resulting in a sequestration phenotype. We find that HFE is upregulated in GBM tumors compared to non-tumor brain and that expression of HFE increases with tumor grade. Furthermore, HFE mRNA expression is associated with significantly reduced survival specifically in female patients with GBM. Based on these findings, we hypothesize that GBM tumor cells upregulate HFE expression to augment cellular iron loading and drive proliferation, ultimately leading to reduced survival of female patients. To test this hypothesis, we generated Hfe knockdown and overexpressing mouse glioma cell lines. We observed significant alterations in the expression of several iron handling genes with Hfe knockdown or overexpression, suggesting global disruption of iron homeostasis. Additionally, we show that knockdown of Hfe in these cells increases apoptosis and leads to a significant impairment of tumor growth in vivo. These findings support the hypothesis that Hfe is a critical regulator of cellular iron status and contributes to tumor aggression. Future work will include further exploration of the mechanisms that contribute to these phenotypes as well as interactions with the tumor microenvironment. Elucidating the mechanisms by which iron effulx contributes to GBM may inform the development of next-generation targeted therapies.
CBIO-13. EPIGENETIC DEREGULATION OF NUCLEAR TRANSLOCATION - A NOVEL MECHANISM FOR TREATMENT RESISTANCE IN GLIOBLASTOMA
Authors: Nguyen Thi Tham , Rajakannu Premnath , Pham Minh Diêu Thanh , Weman Leo , Jucht Alexander , Van Dommelen Kristof , Hegi Monika
Published: December 2020

In a genome-wide DNA methylation analysis of glioblastoma we identified aberrant methylation of the HIV-1 Tat interactive protein 2 (HTATIP2) gene promotor. This was strongly correlated with downregulation of HTATIP2 gene expression, suggesting a potential tumor suppressor function in glioblastoma. HTATIP2 has been shown to inhibit nuclear translocation through interaction with β-importins. We hypothesize that deregulation of HTATIP2 expression inhibits nuclear entry of cancer-relevant proteins, thereby disturbing their specific function in the nucleus. We identified N-Methylpurine-DNA Glycosylase (MPG) as a potential cancer relevant candidate with the observation of nuclear and/or cytoplasmic localization in glioblastoma. MPG is a DNA repair protein that recognizes DNA lesions (N7-meG, N3-meA) and initiates base excision repair. We have shown that nuclear MPG expression contributes to resistance of glioblastoma to treatment with the alkylating agent temozolomide. Here we investigated the effect of HTATIP2 on cellular localization of MPG using (i) an inducible system (TET-ON) to express HTATIP2 in non-expressing glioblastoma cells, and (ii) HTATIP2-targeting siRNAs to knock down HTATIP2 in cells with endogenous expression. Results from confocal microscopy or Imagestream analyses showed a significant cytoplasmic retention of MPG in presence of HTATIP2, while knock-down of HTATIP2 resulted in nuclear MPG localization. Cytoplasmic retention of MPG in the presence of HTATIP2 was associated with a significant increase in γ-H2Ax signal after treatment with the alkylating agent: methyl methanesulfonate (MMS), suggesting increase in DNA damage. Mechanistically, we found that HTATIP2 co-localizes with importin β1, and excludes MPG localization. Furthermore, HTATIP2 displayed a similar effect on cytoplasmic retention of MPG as pharmacologic inhibition of Importin β 1. Taken together, these results suggest that epigenetic silencing of HTATIP2 may increase nuclear localization of MPG, thereby increasing the capacity of the tumor cells to repair treatment related lesions and thereby contributing to treatment resistance.
CBIO-20. MOLECULAR MECHANISMS OF OLIG2 TRANSCRIPTION FACTOR IN GLIOBLASTOMA
Authors: Saito Norihiko , Sato Sho , Hiramoto Yu , Fujita Satoshi , Nakayama Haruo , Hayashi Morito , Ito Keisuke , Sakurai Takatoshi , Iwabuchi Satoshi
Published: December 2020

Oligodendrocyte lineage transcription factor 2 (OLIG2) promotes proliferation of normal neural stem/progenitor cells and glioma cells. However, the mechanisms underlying the regulation of OLIG2 remain largely unknown. Here, we show that a comprehensive analysis of the critical gene regulatory networks involving OLIG2 in glioma initiating cell (GIC) lines. In vitro differentiation studies showed that proneural GIC lines possess the potential to differentiate into astrocytic, neuronal, and oligodendrocytic lineages, whereas mesenchymal GICs exhibited limited potential for neural lineage differentiation following retinoic acid induction. We also showed that CDK2-mediated OLIG2 phosphorylation stabilizes OLIG2 protein from proteasomal degradation. Phosphorylated OLIG2 binds to the E-Box regions of p27 promoter and represses p27 transcription, which in turn activates CDK2 in positive feedback manner. CDK2-mediated OLIG2 phosphorylation promotes cell cycle progression, cell proliferation, and tumorigenesis. OLIG2 inhibition disrupted cell cycle control mechanism by decreasing CDK2 and elevating apoptosis-related molecules. Inhibition of CDK2 activity disrupted OLIG2-CDK2 interactions and attenuated OLIG2 protein stability.　In addition, OLIG2-high glioma initiating cells are highly sensitive to CDK2 inhibitor treatment, indicating that OLIG2 can be a biomarker for personalized treatment for glioblastoma patients with CDK2 inhibitors. In conclusion, we have identified OLIG2-CDK2 interactions in glioma stem cells that can be targeted by CDK2 inhibitors and this may allow the selection of patients with high likelihood of responding to this therapy.
CBIO-21. H3F3A G34R/V MUTATIONS INDUCE CHROMOSOMAL INSTABILITY AND PROMOTE PEDIATRIC HIGH-GRADE GLIOMA FORMATION
Authors: Day Charles , Grigore Florina , Langfald Alyssa , Robinson James , Hinchcliffe Edward
Published: December 2020

Histone H3.3 G34R/V mutations are drivers of pediatric high-grade glioma (pHGG). However, the mechanism(s) responsible for G34R/V induced tumorigenesis are unclear. We observed that pHGG cells with H3.3 G34 mutations have significantly reduced phosphorylation at H3.3 S31 as compared to H3.3 WT cell lines. And, in vitro, G34 mutation completely blocks H3.3 S31 phosphorylation by Chk1 – the kinase responsible for S31 phosphorylation. During early mitosis, phospho-S31 is enriched in the chromosomal pericentromere; which plays a vital structural role in chromosome segregation. Over-expression of GFP-H3.3 G34R or non-phosphorylatable GFP-H3.3 S31A in chromosomally stable cell lines results in a significant increase in chromosome mis-segregations. Likewise, H3.3 G34V pHGG derived cells showed a higher frequency of mis-segregation than H3.3 WT cells. During cell division, phospho-S31 is lost in late anaphase. However, when chromosome missegregation occurs, phospho-S31 spreads to the chromosome arms where it stimulates p53 accumulation in G1 – thus acting as a sensor to suppress the proliferation of aneuploid cells. Here we show that cells expressing mutant G34 fail to arrest following mis-segregation, despite having WT p53. Taken together this work demonstrates that the H3.3 G34R/V mutations are sufficient to transform normal, diploid cells into proliferative, chromosomally instable cells. To determine if this process contributes to tumorigenesis, we expressed WT H3.3, H3.3-G34R or H3.3-S31A in a mouse model of pHGG. H3.3 WT controls developed low-grade tumors and all survived 80 days. Mice with H3.3-G34R or H3.3-S31A developed low- and high-grade tumors. And 78% and 50% of H3.3-G34R and H3.3-S31A mice, respectively, survived to 80 days. Our work suggests that H3.3 G34R/V drives chromosomal instability through the suppression of H3.3 S31 phosphorylation AND that chromosomal instability is a contributing driver of glioma formation in G34 mutant tumors.
CBIO-22. p53 GAIN-OF-FUNCTION MUTATIONS DRIVE SEX SPECIFIC EFFECTS ON GLIOMA TUMORIGENESIS
Authors: Rockwell Nathan , Warrington Nicole , Rubin Joshua
Published: December 2020

Sex differences in malignant brain tumors are well-established: Males exhibit greater incidence and poorer survival. Understanding the biology behind these sex differences requires investigation of the pathways known to drive gliomagenesis. The transcription factor TP53 (p53) is one of the most commonly mutated genes in glioblastoma. Most p53 mutations are missense mutations in the DNA-binding domain that lead to the expression of a full length mutant p53 protein. These mutations can endow p53 with oncogenic gains-of-function through aberrant DNA binding and regulation of noncanonical cancer-promoting target genes. Previously, we analyzed patient mutation data and identified six p53 mutations with sex differences in prevalence. In this study, we developed an in vitro mutant p53 glioma model to investigate the sex specific effects of three p53 point mutations: R175H, Y205C, and Y220C (Mm R172H, Y202C, and Y217C respectively). Male and female astrocytes isolated from p53flox/- mouse pups were transduced with a retrovirus expressing mutant p53, followed by a lentivirus expressing CRE recombinase to remove the endogenous WTp53. We then assessed cell proliferation, clonogenicity, and in vivo tumorigenesis in these cells. All three mutations assayed displayed sex differences in proliferation, with male cells overexpressing p53:Y202C and p53:Y217C growing faster than female cells, and female cells overexpressing p53:R172H growing faster than male cells. Male Y202C and Y217C expressing astrocytes also exhibited a trend toward greater clonogenicity compared to female astrocytes. This observation is supported by higher expression of the stem cell markers SOX2 and NESTIN in the male cells. We performed parallel flank injections of male and female astrocytes expressing each mutation or p53 KO. Only male astrocytes expressing p53:Y202C or p53:Y217C and female astrocytes expressing p53:R172H mutation were able to form tumors in vivo. Together, these data support a sex specific gain-of-function phenotype for three different p53 mutations observed in glioma.
CBIO-23. PROXIMITY-DEPENDENT BIOTIN IDENTIFICATION (BIOID2) INDICATES MEMBRANE TRAFFICKING AND VESICLE TRANSPORT AS A POTENTIAL NOVEL FUNCTION OF EXTRACELLULAR SIGNAL-REGULATED KINASE 5 (ERK5)
Authors: Stanton Ann-Catherine , Koller Antonius , Koncar Robert , Golbourn Brian , Halligan Katharine , Halbert Matthew , Mack Stephen , Pollack Ian , Agnihotri Sameer
Published: December 2020

INTRODUCTION

Pediatric High-Grade Gliomas (PHGG), which include Diffuse Midline Gliomas (DMG), are a leading cause of brain tumor death in children. Our recent work has identified extracellular signal-regulated kinase 5 (ERK5) as a critical mediator of cell survival in DMG, as ERK5 knockdown decreases cell proliferation and extends survival time in orthotopic xenograft mice. Further investigation into the structure of ERK5 shows that it has a kinase domain and, unlike other ERKs, a transactivation domain, and both are important for promoting cell proliferation.

HYPOTHESIS AND METHODS

We hypothesize that identifying interactors and substrates of ERK5 could identify clinically actionable proteins and provide a more mechanistic insight into ERK5 in the progression of PHGGS. To determine protein–protein associations (PPAs), we employed the proximity-dependent biotin identification (BioID2) method and generated inducible ERK5-BioID2 and ERK2-BioID2 constructs to overcome barriers of conventional screening methods for PPAs. ERK2, similar in structure but much more studied than ERK5, was used as a comparison. Using DIPG lines as proof of principle, we performed streptavidin pull down assays for putative biotinylated ERK PPA and followed with mass spectrometry to identify the ERK2 and ERK5 interactomes.

RESULTS

Using data-dependent acquisition (DDA), we identified several unique and common interactors of ERK5 compared to ERK2. Through STRING network and pathway analysis, we identified a novel function of ERK5 with respect to membrane trafficking and vesicle transport. Identification of interactors with ERK5 may lead to effective therapeutic combinations. Our current work is focused on validating these interactions and the function of ERK5 in these biological processes.

CONCLUSIONS

Currently, ERK5 is not as understood as ERK1 or ERK2. Identification of interactors and substrates of ERK5 will further our understanding of PHGG biology, and may lead to identifying druggable targets and pathways.
COVD-01. ADAPTATION OF A GAMMA KNIFE ICON STEREOTACTIC RADIOSURGERY PROGRAM IN THE FACE OF A GLOBAL PANDEMIC
Authors: Wegner Rodney , Horne Zachary , Xu Linda , Yu Alexander , Goss Matthew , Liang Yun , Sohn Jason , Colonias Athanasios , Fuhrer Russell , Karlovits Stephen
Published: December 2020

PURPOSE

The COVID-19 pandemic necessitated drastic and rapid changes throughout the field of radiation oncology, some of which were unique to the discipline of radiosurgery. Available guidelines called for reduced frame use, postponing non-urgent cases, and reducing the number of fractions delivered. Our institution enacted many of these guidelines, and herein we show the resultant effect on patient treatments on our Gamma Knife Icon system.

METHODS & MATERIALS

In early to mid-March of 2020 our institution rapidly implemented suggested changes according to ASTRO and other consensus guidelines as they relate specifically to stereotactic radiosurgery in the COVID-19 era. We reviewed the GK Icon schedule at our institution between January 01 and April 30, 2020. We documented age, condition treated, technique (frame vs. mask), and number of fractions. We then tabulated and graphed the number of patients, framed cases, and fractions across that time period.

RESULTS

Seventy-seven patients were treated on the GK Icon between January and April 2020, for a total of 231 fractions. The number of unique patients per month varied from 18 (April) to 22 (January). Of the 77 patients only 5 were treated using a frame. The number of fractions per month decreased significantly over time, from 70 in January to 36 in April. Likewise, the percentage of single fraction cases increased from 4.5% per month in January to 67% in April.

CONCLUSIONS

The results presented here show that it is possible to quickly and efficiently change work flows to allow for reduced fractionation and frame use in the time of a global pandemic. Multidisciplinary cooperation and ongoing communication are integral to the success of such programs.
COVD-06. BRAIN TUMOURS AND COVID-19: THE PATIENT AND CAREGIVER EXPERIENCE
Authors: Voisin Mathew , Oliver Kathy , Farrimond Stu , Chee Tess ,   IBTA Senior Advisors, Zadeh Gelareh
Published: December 2020

BACKGROUND

Since the COVID-19 pandemic, thousands of medical procedures and appointments have been cancelled or delayed. The long-term effects of these drastic measures directly on brain tumour patients and their caregivers are unknown. The purpose of this study is to better understand how COVID-19 has affected this vulnerable population on a global scale.

METHODS

An online 79-question survey was developed by the IBTA, in conjunction with the SNO COVID-19 Task Force. The survey was sent to over 120 brain tumour charities and not-for-profits worldwide and disseminated to brain tumour patients and caregivers. All responses were subdivided by patient vs caregiver and by geographical region.

RESULTS

In total, 1989 participants completed the survey from 33 countries, including 1459 patients and 530 caregivers. There were no significant differences in COVID-19 testing rates (p = 0.662) or the number of positive cases for brain tumour patients between regions (p = 0.1068). Caregivers were significantly more anxious than patients (p = < 0.0001). Patients from the Americas were most likely to have lost their jobs due to the pandemic, practiced self-isolation, and received telehealth services (p = < 0.0001). Patients from Europe experienced the most treatment delays (p = 0.0031). Healthcare providers were ranked as the most trusted source of information.

CONCLUSIONS

As a result of COVID-19, brain tumour patients and caregivers have experienced significant stress and anxiety. Healthcare professionals, brain tumour charities, and not-for-profits must ensure that they continue to provide accessible, high-quality care, information, and support in the age of COVID-19.
COVD-13. EFFECTS OF COVID-19 PANDEMIC ON NEUROSURGICAL ONCOLOGY PRACTICES AT INOVA HEALTH SYSTEM: AN INSTITUTIONAL EXPERIENCE
Authors: Dang Danielle , Mugge Luke , Awan Omar , Gunnells Emily , Vaughan Megan , Ziu Mateo
Published: December 2020

INTRODUCTION

Amidst the unprecedented nationwide ban on elective surgeries during the COVID-19 pandemic, concern regarding timely and safe treatment of patients with intracranial tumors has been raised in the neuro-oncology community.

METHODS

A retrospective chart review was performed on all patients who underwent treatment for intracranial tumors from 3/12–7/1 for 2019 and 2020. Dates aligned with declaration of State of Emergency through the multi-phase public re-opening. Primary comparative endpoints included case volume, median time to surgery, chemotherapy, and radiation, and COVID-related mortality.

RESULTS

Overall surgical case volume decreased by 26.6%, while a 46.9% decrease was evident during the ban on elective surgeries. Case reduction occurred only for glial (p= 0.33) and pituitary tumors (p=0.04) where volume was nearly identical for other tumors. Median time to surgery was 2.5 days (range: 0–9) for high-grade glioma patients, 3 days for metastases, 3 days for meningiomas, and 26 days (range: 0–98) for pituitary adenomas, not significantly different from 2019. Time to chemoradiation and planned number of treatments were without significant difference. Among 2,795 Covid-19 patients treated in our institution, only four had brain tumors. Only one patient experienced delayed radiation treatment (three weeks) due to inability to achieve seroconversion prior to planned simulation. Only one COVID-related mortality in our cohort occurred.

DISCUSSION

The pandemic did not significantly delay type and time to treatment for neuro-oncology patients at Inova. With swift implementation of PPE and strict peri-operative testing, we provided standard of care treatment without increases in COVID-19 contraction or mortality. Decreases in overall case volume are likely due to ongoing cultural avoidance of seeking medical care; deferment of endonasal surgery may be attributed to a known greater mortality for ENT procedures. Future patient care challenges include establishing clinical significance of seroconversion for asymptomatic, COVID-19 infected patients without delaying necessary systemic treatment.
COVD-19. COGNITION, CANCER, AND COVID: DELIVERING DIRECT-TO-HOME TELE-NEUROPSYCHOLOGY SERVICES TO NEURO-ONCOLOGY PATIENTS
Authors: Gardner Melissa , Aslanzadeh Farah , Zarrella Giuliana , Braun Sarah , Loughan Ashlee , Parsons Michael
Published: December 2020

BACKGROUND

The COVID-19 pandemic altered the delivery of healthcare services globally with a rapid adoption of telemedicine to meet patient’s needs. Telemedicine is critical for neuro-oncology patients who may be at an increased risk of infection, yet require continuity of care. An important aspect of neuro-oncology care includes neuropsychological assessment, which can be challenging to complete outside of a structured testing environment. Teleneuropsychology (TNP) has been explored under proctored conditions and proven feasible and reliable. Conducting TNP visits directly to the patients’ home (DTH-TNP) had minimal study prior to the pandemic, but was implemented to reduce COVID-19 exposure.

METHODS

We used surveys to examine patient acceptance and clinician feasibility of DTH-TNP at two regionally diverse medical institutions routinely providing neuropsychological assessments services to neuro-oncology patients from April to August 2020, Massachusetts General Hospital (MGH) and Virginia Commonwealth University (VCU).

RESULTS

45 patients voluntarily responded (MGH=30, VCU=15) and 98 percent (MGH=100%, VCU=93%) of respondents were satisfied with the DTH-TNP experience. Nine percent (MGH=7%, VCU=13%) reported challenges (e.g., technological issues) during the appointment. Eighty-nine percent (MGH=90%, VCU=87%) would recommend the virtual visit to others. Patients perceived reduced risk of infection (MGH=77%, VCU=87%) and time traveling to clinic (MGH=87%, VCU=80%) as favorable aspects of DTH-TNP. 43 clinician surveys collected at MGH indicated that clinicians were able to achieve the goal of their appointment in 91% of clinical encounters. Common issues reported by clinicians included trouble connecting (7%) to the telemedicine platform and environmental disruptions (12%).

DISCUSSION

This preliminary data suggests neuro-oncology patients and clinicians find DTH-TNP to be an acceptable and feasible practice, while also recognizing its limitations. This study is limited in that voluntary patient surveys are subject to bias. These results suggest that further study of DTH-TNP (e.g., reliability, validity, and limitations) for neuro-oncology patients is warranted. Future directions are discussed.
COVD-26. TELEPHONE CONSULTATIONS IN NEURO-ONCOLOGY DURING THE COVID-19 PANDEMIC: LEVELS OF PATIENT SATISFACTION AND COMPARISON WITH TRADITIONAL FACE-TO-FACE CONSULTATIONS
Authors: Toman Emma , Goddard Claire , Berki Frederick , Garratt William , Scott Teresa , Sher Zenab , Stevens Andrew , Petrik Vladimir , Ughratdar Ismail , White Anwen , Zisakis Athanasios , Watts Colin , Wykes Victoria
Published: December 2020

INTRODUCTION

Controversy exists as to whether telephone clinics are appropriate in neurosurgical-oncology. The COVID-19 pandemic forced neuro-oncology services worldwide to re-design and at the University Hospitals Birmingham UK, telephone clinics were quickly implemented in select patients to limit numbers of patients attending hospital. It was important to determine how these changes were perceived by patients.

METHODS

A 20-question patient satisfaction questionnaire was distributed to patients who attended neuro-oncology clinic in person (“face-to-face”), or via the telephone. Fisher’s exact test was used to determine significance, which was set at p< 0.05.

RESULTS

Eighty questionnaires were distributed between June 2020 and August 2020. Overall, 50% (n=40) of patients returned the questionnaire, 50% (n=23) of face-to-face and 50% (n=17) telephone patients. Of those who received telephone consultations, 88% (n=15) felt the consultation was convenient, 88% (n=15) were satisfied with their consultation and 18% (n=3) felt they would have preferred to have a face-to-face appointment. Of those who attended clinic in person, 96% (n=22) felt their consultation was convenient, 100% (n=23) were satisfied with their consultation and 13% (n=3) would have preferred a telephone consultation. Within the face-to-face clinic attendees, only 13% (n=3) were concerned regarding the COVID risk associated with attending hospital. There was no significant difference in patient convenience or satisfaction (p=0.565 and p=0.174 respectively) between face-to-face and telephone clinics. There was no significant difference in whether patients would’ve preferred the alternative method of consultation (p > 0.999).

CONCLUSION

Our study suggests that careful patient selection for neuro-oncology telephone clinic is not inferior to face-to-face clinic. Telephone clinic during COVID-19 pandemic proved to be convenient, safe and effective. This global health crisis has transformed telephone neuro-oncology consultations from an experimental innovation into established practice and should be continued beyond the pandemic in select cases.
COVD-29. CONTINUATION OF TEMOZOLOMIDE CHEMOTHERAPY IN A GLIOBLASTOMA PATIENT AFTER RESOLUTION OF COVID-19 PNEUMONIA
Authors: Thakkar Jigisha , Teitcher Michael , Anderson Douglas , Barton Kevin , Melain Edward
Published: December 2020

We present a case of a 33 year-old patient with glioblastoma (IDH wild type, MGMT unmethylated) who was diagnosed with COVID-19 pneumonia while undergoing chemotherapy. The patient did not have any medical comorbidities. He was clinically asymptomatic following surgery, completed concurrent phase of combined chemotherapy and radiation and was undergoing treatment with adjuvant temozolomide. He had radiographic improvement of the brain tumor (decreased size, contrast enhancement and T2 flair) after three cycles of adjuvant temozolomide. However, after cycle three the patient developed fever and abdominal pain. Evaluation in the emergency room revealed low absolute lymphocyte count (0.7 K/MM3), positive COVID-19 point of care test and CT chest revealed patchy peripheral bibasilar ground glass and consolidative opacities compatible with pulmonary infection, with viral etiology such as COVID. Symptoms resolved after 2 weeks. Due to active infection and leucopenia temozolomide was on hold for 1 month. He was considered cleared of infection after resolution of symptoms. Temozolomide was initiated after resolution of leucopenia. Patient continued to do well after administration of subsequent temozolomide cycles and repeat CT chest after 2 months revealed resolution of consolidation and no new areas of consolidation. Temozolomide was safely administered in this patient without reactivation of COVID-19 infection. He did not have any thrombotic events.
CSIG-01. IDENTIFICATION OF PATHOGENESIS-RELEVANT microRNAs IN BRAIN METASTASIS
Authors: Mulcahy Elizabeth , Colon Rossymar , Zhang Ying , Gibert Myron , Kim Jungeun , Devairakkam Eric , Abounader Roger , Fadul Camilo
Published: December 2020

When brain metastasis develops, the prognosis of cancer is dismal. Insights into the biology of the primary cancer and the brain metastasis are necessary to inform more effective and targeted treatments. To study the role of microRNAs in brain metastasis, we performed differential expression profiling of 12 primary tumors and their paired brain metastases using smRNAseq (the 12 primary tumors included three non-small cell carcinomas, three melanomas, three endometrial carcinomas, one breast carcinoma, one thyroid carcinoma and one renal-cell carcinoma). To start, we identified microRNAs that were either highly upregulated or downregulated in the brain metastasis samples as compared to the paired primary tumors. After confirmation with real-time quantitative PCR, we further investigated the top microRNAs from both groups through functional assays performed in cell lines generated from primary melanoma, melanoma lymph node metastasis, and melanoma brain metastasis. From this top-down, patient sample to model cell-line approach we identified two microRNAs that are potentially important regulators in the development of brain metastasis. Characterization of their targets and their interactions may offer a therapeutic opportunity to improve the prognosis of patients with brain metastasis.
CSIG-06. PLATELET DERIVED GROWTH FACTOR RECEPTOR ALPHA AS AN ONCOGENIC DRIVER IN GLIOBLASTOMA
Authors: Berezovsky Artem , Irtenkauf Susan , Transou Andrea , Hasselbach Laura , Mikkelsen Tom , de Carvalho Ana
Published: December 2020

Activated platelet derived growth factor receptor alpha (PDGFRα) is essential for the maintenance of oligodendrocyte progenitors. Differential signaling results from phosphorylation of specific tyrosine residues in the kinase insert (KI) domain present in most RTKs in variable length. Our goal is to identify the molecular contexts in which PDGFRA activation is an essential driver for maintenance of the malignant phenotype in glioblastoma. RNA sequencing was conducted on 13 glioblastoma mouse orthotopic PDXs (n=3/line). PDGFRA mRNA overexpression was observed for 3 glioblastomas: one carrying PDGFRA extrachromosomal (ecDNA) amplification (HF3253) and two non-amplified (Tukey p=0.41, 0.19). Corresponding PDGFRα KI activation (pY754) was observed only for HF3253. To assess activation as an adaptation to microenvironmental pressures, pY754 was quantified by reverse phase protein array on 4 growth conditions (normal, -growth factors, two serum concentrations) for 8 neurospheres. PDGFRɑ activation was highest in growth factor-depleted conditions in the absence of exogenous ligand (Tukey p=0.02). Taking advantage of genomic heterogeneity in HF3253, we isolated cellular lineages with divergent frequencies of PDGFRA ecDNA. PDGFRA copy number (TaqMan) decreased longitudinally. PDX tumors from higher passage had slower tumor growth due to strong selection for initial low frequency PDGFRA ecDNA-amplified clones. IHC showed that the tumors had comparably high total and activated PDGFRα to low passage tumors. Further exploiting intra-tumoral heterogeneity, we have isolated single cell clones. Tumor growth was reduced in 2 ecDNA(-) tumors compared to parental ecDNA(+) (log-rank test p= 3e-3, 1e-3). In contrast to parental, ecDNA(-) tumors demonstrated diffuse tumor morphology and weak PDGFRα activation. The staining index (mean intensity x area) for the ecDNA(-) clones was significantly lower than the ecDNA(+) (1-wayANOVA p=2e-16). We established dependency on PDGFRα signaling in a patient-derived glioblastoma model. Our data demonstrates that detection of ecDNA-amplified PDGFRA has the potential to be a predictive biomarker of future PDGFRɑ-targeted therapies.
CSIG-13. TRPM7 INDUCES TUMORIGENESIS AND STEMNESS THROUGH NOTCH ACTIVATION IN GLIOMA
Authors: Wan Jingwei , Guo Alyssa , Liu Mingli
Published: December 2020

Our group found that the inhibitory effect of TRPM7 on proliferation and invasion of human glioma cell is mediated by multiple mechanisms. TRPM7 regulates miR-28-5p expression, which suppresses cell proliferation and invasion in glioma cells by targeting Ras-related protein Rap1b. In particular, our group found that TRPM7 channels regulate glioma stem cell (GSC) growth/proliferation through STAT3 and Notch signaling. However, which Notch component(s) is crucial for its activity regulated by TRPM7, and its relationship with other GSC markers, such as CD133 and ALDH1, remain unclear. In the current project, we elucidate the mechanisms of TRMP7’s regulation of Notch signaling pathway that contribute to the development and progression of glioma and maintenance of self-renewal and tumorigenicity of GSC using multiple glioma cell lines (GC) with different molecular subtypes and GSCs derived from the GC lines. 1) We first analyzed TRPM7 expression using the Oncomine database (https://www.oncomine.org) and found that the TRPM7 mRNA expression is significantly increased in anaplastic astrocytoma, diffuse astrocytoma, and GBM patients compared to that in normal brain tissue controls. 2) TRPM7 is expressed in GBM, and its channel activity is correlated with Notch1 activation. Inhibition of TRPM7 downregulates Notch1 signaling, while upregulation of TRPM7 upregulates Notch1 signaling. 3) GSC markers, CD133 and ALDH1, are correlated with TRPM7 in GBM. 4) Targeting TRPM7 suppresses the growth and proliferation of glioma cells through G1/S arrests and apoptosis of glioma cells. 5) Targeting Notch1 suppresses the TRPM7-induced growth and proliferation of glioma cells, as well as the expression of GSC markers CD133 and ALDH1. In summary, TRPM7 is responsible for sustained Notch signaling activation, enhanced expression of GSC markers, and regulation of glioma stemness, which contribute to malignant glioma cell growth and invasion. Notch1 and ligand DII4 are key components that contribute GSC stemness.