bluuebunny/crossref_metadata_2025 huggingface dataset:
DDRE-32. SETD2 HISTONE METHYLTRANSFERASE MUTATION STATUS PREDICTS TREATMENT RESPONSE IN GLIOBLASTOMA: STRATEGIES TO OVERCOME CHEMORESISTANCE
Authors: Goldstein Michael , Gabriel Nishanth , Inkman Matthew , Zhang Jin , Dahiya Sonika
Published: November 2021

A major challenge in GBM treatment is tumor resistance to radiation and chemotherapy. A hallmark of GBM is the frequent mutation of epigenetic modifiers resulting in alteration of epigenetic signaling pathways. However, the effect of epigenetic signaling on chemotherapy response in GBM remains unknown. SETD2 is a histone methyl transferase that facilitates H3K36 tri-methylation. Here, we unveil the role of SETD2 mutations that frequently occur in GBM in tumor resistance to temozolomide chemotherapy. Targeted sequencing of the SETD2 gene in GBM tumor samples revealed that SETD2 mutations are associated with reduced overall survival in patients with methylated MGMT (methyl-guanine methyl transferase) promotor who received temozolomide. Consequently, we demonstrate that loss of SETD2 results in reduced H3K36me3 levels and a profound temozolomide resistance in GBM cells. MGMT-deficient tumors can acquire chemoresistance due to disrupted mismatch repair (MMR), a DNA repair pathway that converts primary temozolomide-induced DNA lesions into toxic DNA double-strand breaks. Strikingly, we found that SETD2 loss abrogates the expression of the MMR factor MSH6 indicating that chemoresistance in SETD2-deficient cells us due to disrupted MMR. Mechanistically, we show that SETD2 regulates MMR by promoting transcription of the MSH6 gene in GBM. Epigenetic modifiers have specific antagonists capable of reversing chromatin alterations induced by these modifiers. This provides a unique opportunity to restore chemotherapy response in SETD2-mutant GBM by targeting the antagonists of SETD2. We demonstrate that combined targeting of H3K36me3-specific histone de-methylases KDM4A and NO66 restores H3K36me3 levels along with MSH6 expression and sensitivity to temozolomide in SETD2-deficient GBM cells. Thus, our findings establish SETD2 mutation as a novel molecular marker predictive of chemotherapy response in GBM and provide a framework for a novel approach to overcome chemotherapy resistance in this malignant brain tumor by targeting an epigenetic pathway.
DDRE-39. REPURPOSING CHEMOTHERAPIES AGAINST HIGH-RISK MENINGIOMAS WITH GUIDANCE BY METHYLATION PROFILES
Authors: Tran Anh , Wang Wenxia , Scholtens Denise , Zhang Lyndsee , Pokorny Jenny , Wang Yufen , Baran Aneta , Sahm Felix , Aldape Kenneth , James David , Horbinski Craig
Published: November 2021

Meningioma is the most common primary brain tumor with nearly thirty thousand new cases in the US every year. While most meningiomas are categorized as benign, they can still impact brain structures and result in disability or lethality. Currently, there is no widely accepted chemotherapy, and our understanding of the disease’s molecular characteristics is very limited. In this study, we aimed to identify druggable molecular targets for repurposing of chemotherapies against meningiomas. We analyzed previously published dataset of 493 meningioma patients by Felix Sahm et al (Lancet Oncology, 2017) for association with progression-free survival (PFS) and searched for candidate drugs targeting the pathways linked to poor patient prognosis. Our analyses indicated 981 genes for which methylation of mapped CpG sites was found to be consistently associated with shorter or longer PFS at FDR-adjusted p < 0.05. Using Cytoscape/Reactome FI software, we cross-referenced current cancer drugs that target these and identified docetaxel and raloxifene hydrochloride as potential candidates. In our vitro study, docetaxel caused apoptotic cell death in established and primary patient meningioma lines of various grades. IC50s of docetaxel in the seventeen meningioma cell lines tested ranged from 0.8nM to 4.4mM, which partially corresponded to the growth rates of these cells. As monotherapy, the effects of docetaxel on meningioma were attenuated by multidrug resistance protein 1 (ABCB1) and Cytochrome P450 1B1 (CYP1B1). Docetaxel at 2µM augment double-stranded DNA damage caused by irradiation in vitro, leading to increased cell death. In animal model, low doses of docetaxel and radiation therapy had synergistic effects, increasing survival of mice intracranially implanted with human meningioma cells. Our study will advance our understanding of molecular pathways driving meningioma and identify potential targeted therapies to bridge the current gap in treatment of the disease.
DDRE-50. INVESTIGATING THE ROLE OF LonP1 IN GLIOBLASTOMA TUMOR PROGRESSION
Authors: Douglas Christopher , Bota Daniela , Di Kaijun , Das Bhaskar , Lepe Javier
Published: November 2021

Glioblastoma (GBM), a WHO grade IV brain cancer, exhibits strong treatment resistance and a high rate of reoccurrence, which gives it a dismal prognosis, a 5% survival rate in the first 5 years. LonP1, a mitochondrial master regulator, can drive metabolic transformation, cytokine production, EMT, and treatment resistance in various cancer types, but its role in GBM remains unexplored. Our research group has previously shown that LonP1 is overexpressed in human malignant gliomas, particularly glioblastoma, and that this is associated with disease prognosis. Here, we present findings that demonstrate that LonP1 seems to drive enhanced tumor progression, invasiveness, angiogenesis in different high grade glioblastomas based on TCGA-subtype. Furthermore, in collaboration with Professor Bhaskar Das, we have validated a lead compound, BT317, with on-target inhibition of LonP1 protease activity. BT317 has enhanced activity against glioma stem cell lines (GSC) and has demonstrated low toxicity and efficacy in an intracranial xenograft model. This preliminary data highlights the potential of using combinatorial, pharmacological LonP1 and proteasome inhibition as a novel strategy for targeting specific subtypes of GBM.
EPID-04. THE NATURAL HISTORY OF NEUROFIBROMATOSIS-1, THE MONTEFIORE EXPERIENCE
Authors: Lin Tiffany , Dalvi Nagma
Published: November 2021

Neurofibromatosis type 1 (NF1) is a genetic disorder with varying phenotypes that can affect many organ systems. Notably, it has significant clinical variability involving different systems in each individual. Manifestations may also develop and evolve with age. Although current literature has looked into the prevalence of the manifestations of NF1, few have compared the prevalence in populations of diversity. The objective of our study is to describe the clinical manifestations of NF1 seen in an urban neurocutaneous clinic that serves a diverse ethnic and socioeconomic population. We intend to see how the clinical manifestations of our patients compare to what is reported and to better understand the clinical impact and prognoses of NF1 in this population. We performed a retrospective study of patients in our neurocutaneous clinic from May 2014 to December 2020. Of the 89 that fit study criteria, we had a majority of Hispanic and Black patients. We compared our data to two recent NF1 natural history studies, Boulanger et al. and Cnossen et al., using chi-square or Fisher exact test. Results showed that we had a lower incidence of cutaneous neurofibromas (23.6% vs the reported 40%) and lisch nodules (32.6% vs the reported 50%), but a higher incidence of symptomatic plexiform neurofibromas (48.3% vs the reported 25%) and CNS tumors requiring intervention (4.5% vs estimated 2% in compared studies). This may indicate that our population is at higher risk for more serious complications. We speculate that socioeconomic and ethnic diversity may be the driver behind these differences. Our center has also initiated treatment using MEK inhibitors in indicated patients. Due to the differences in clinical manifestations and more severe complications, we recommend closer surveillance in diverse populations. We also advocate for further research in the application of MEK inhibitors beyond second-line therapy.
EPID-06. ASSOCIATIONS BETWEEN GERMLINE GENETIC VARIANTS AND OVERALL SURVIVAL IN PATIENTS WITH GLIOMA
Authors: Potnis Kunal , Ostrom Quinn , Claus Elizabeth
Published: November 2021

BACKGROUND

In addition to somatic genetic variation in tumors, germline genetic variation can better define cancer susceptibility risk, guide therapy, and predict survival. Most prior research into associations between germline genetic variants and survival outcomes in patients with glioma has been limited by small sample sizes and to high-grade glioma only. This study is the first to use data from Brigham and Women’s Hospital (BWH) and to include both low-grade and high-grade glioma cases to explore associations between germline genetic variants and overall survival.

METHODS

This study included 211 patients enrolled at BWH from April 2010 to January 2020. Ninety-two candidate germline genetic variants were identified via literature review. Fifty-five variants with minor allele frequency >0.05 were included preliminarily, for which bivariate Cox proportional hazards regression models were employed. Twenty-two variants with P< 0.5 were included in the final multivariable model, adjusted for patient sex, age, race, and glioma grade. Stratified sub-analyses were also conducted by sex. Associations were considered statistically significant at P< 0.05.

RESULTS

Among all patients, homozygous C/C genotype at rs17655 (ERCC5 gene) was significantly associated with worse overall survival (hazard ratio=2.61, P=0.0095). Among females only, worse survival was associated with homozygous T/T genotype at rs1381057 (POLQ, hazard ratio=2.58, P=0.046). Among males only, heterozygous status for the A genotype at rs487848 (POLQ, hazard ratio=0.31, P=0.018) and the A genotype at rs1468923 variant (PIK3CA, hazard ratio=0.51, P=0.016) were associated with improved survival.

CONCLUSION

We identified statistically significant associations between overall survival and four variants in genes involved in DNA repair and the PIK3 pathway, three of which were sex-specific. Our results contribute to improving patient stratification in glioma and may lead to increased targeting of treatment strategies.
EPID-09. VARIATION IN GLIOMA INCIDENCE AMONG US HISPANICS BY GEOGRAPHIC REGION OF ORIGIN
Authors: Walsh Kyle , Bondy Melissa , Kruchko Carol , Huse Jason , Amos Christopher , Barnholtz-Sloan Jill , Ostrom Quinn
Published: November 2021

BACKGROUND

Glioma incidence is 25% lower in U.S. Hispanics than in White non-Hispanics. The US Hispanic population is diverse and registry-based analyses may mask incidence differences associated with geographic/ancestral origins.

METHODS

County-level glioma incidence data in U.S. Hispanics were retrieved from the Central Brain Tumor Registry of the United States (CBTRUS), which includes data from the Centers for Disease Control’s National Program of Cancer Registries and the National Cancer Institute’s Surveillance, Epidemiology, and End Results program and covers ~100% of the U.S. population. American Community Survey (ACS) data were used to determine county-level proportion of the Hispanic population of Mexican/Central American origin, Caribbean origin (Puerto Rican, Cuban, Dominican), or other origin. Incidence rate ratios (IRRs) were generated to assess the association of glioma incidence in Hispanics with predominant origin group.

RESULTS

Compared to Hispanics living in predominantly Caribbean-origin counties, Hispanics in predominantly Mexican/Central American-origin counties were at lower age-adjusted risk of glioma (IRR=0.83; P< 0.0001), glioblastoma (IRR=0.86; P< 0.0001), diffuse and anaplastic astrocytoma (IRR=0.78; P< 0.0001), oligodendroglioma (IRR=0.82; P< 0.0001), ependymoma (IRR=0.88; P=0.0121), and pilocytic astrocytoma (IRR=0.76; P< 0.0001). Associations were consistent in children and adults, and when using more granular regions of origin. However, Central American origin was associated with modestly increased incidence of several lower-grade glioma histologies. Associations were only partially attenuated after adjusting for state-level estimated of European admixture in Hispanics using 23andMe data.

CONCLUSIONS

Glioma incidence in U.S. Hispanics differs significantly in association with the geographic origins of the Hispanic community, with those of Mexican/Central American origin at significantly reduced risk relative to those of Caribbean origin. U.S. Hispanics are culturally, socioeconomically, and genetically diverse. Although classified as a single ethnic group in most registry data, more granular analytic approaches could advance cancer epidemiology and disparities research.
EPID-14. EPIDEMIOLOGY OF ADULT PITUITARY TUMORS IN THE U.S. ACCORDING TO THE 2017 WHO CLASSIFICATION OF ENDOCRINOLOGY TUMOURS
Authors: Castellanos Luz , Gutierrez Catherine , Smith Timothy , Iorgulescu Bryan
Published: November 2021

INTRODUCTION

Among adult intracranial tumors, the pituitary represents a frequent site of origin. We examine their contemporary epidemiology with a particular focus on uncommon pituitary tumor types.

METHODS

Adult patients presenting with pituitary or sellar tumors between 2004-2017 were identified from the U.S. National Cancer Database (comprising >70% of newly-diagnosed cancers). Their epidemiology was assessed in the context of the 2017 WHO Classification of Endocrine Tumours.

RESULTS

12.5% of adult intracranial tumors arose in the pituitary region. 113,352 adults with pituitary tumors were identified. Histopathological diagnosis was obtained in only 59% of cases, in which 93% were pituitary adenomas and 6% were craniopharyngiomas. Among craniopharyngiomas, 71% were adamantinomatous and 29% were papillary, between which there were no differences in age, sex, or tumor size—however, papillary craniopharyngiomas were less common among Black nonHispanic patients (p< 0.001). Among the remaining 1% (n=680) of pituitary tumors, posterior pituitary tumors comprised 21%, chordomas 16%, meningiomas 15%, pituitary carcinomas 11%, GCTs 10%, hematolymphoid 8%, other mesenchymal and stromal 7%, neuronal/paraneuronal 6%, and schwannoma 4%. Meningiomas (84%), mesenchymal/stromal (64%), and neuronal/paraneuronal (64%) tumors displayed a female predominance, whereas GCTs (75%) and pituitary carcinomas (62%) exhibited a male predominance. Age at diagnosis, tumor size, and race/ethnicity varied widely across uncommon tumor types. We further examined the subtypes of uncommon pituitary tumors: for sellar chordomas, 19% were chordoid and none were dedifferentiated; for sellar meningiomas, 94% were grade I; for pituitary GCTs, 79% were pure germinomas; for hematolymphoid, 52% were DLBCL, 11% were plasmacytomas, and 9% were Langerhans cell histiocytosis; for neuronal/paraneuronal, 64% were gangliocytomas; and for mesenchymal tumors, 53% were vascular and 16% were SFTs/HPCs.

CONCLUSIONS

Using national registry data, we provide a detailed dissection of the epidemiology of adult pituitary tumors, with a particular focus on examining uncommon pituitary tumor types in the context of WHO2017.
EPID-17. COMPARATIVE EPIDEMIOLOGY OF PRIMARY BRAIN TUMORS AMONG ADOLESCENTS AND YOUNG ADULTS (AYA)
Authors: Lamba Nayan , Iorgulescu Bryan
Published: November 2021

INTRODUCTION

We utilized national registry data to evaluate the unique epidemiology of primary adolescent and young adult (AYA) brain tumors according to the WHO2016 classification.

METHODS

AYA patients (15≤age≤39) presenting between 2004-2017 with a brain tumor were identified by ICD-O-3 coding from the National Cancer Database (comprising >70% of newly-diagnosed cancers in the U.S.), and compared to pediatric and adult populations. Epidemiology and overall survival (estimated by Kaplan-Meier techniques and multivariable Cox regression) were assessed by WHO2016 tumor type.

RESULTS

108,705 AYA brain tumor patients were identified (56.9% female), compared to 23,928 pediatric (46.8% female) and 748,272 adult (55.6% female) patients. Among the 69.4% of AYA brain tumors with pathological diagnosis, diffuse gliomas (31.4%), sellar tumors (19.2%), and meningiomas (15.3%) predominated in both sexes. Diffuse glioma (31.4%), sellar (19.2%), cranial nerve (7.3%), and mesenchymal non-meningothelial (4.1%) tumors represented a greater proportion of AYA brain tumors than in either pediatric or adult populations. A majority of all intracranial GCTs (59.2%) and neuronal & mixed neuronal-glial tumors (51.6%) presented during AYA. Although the prevalence of diffuse gliomas was similar between AYAs and adults, AYA gliomas were more likely to be grade 2-3 astrocytomas (38.9% vs 14.3%) and oligodendrogliomas (19.3% vs 4.3%) than in adults. GBMs represented 76.0% of adult diffuse gliomas vs. only 25.7% of AYA diffuse gliomas, but with a similar prevalence of MGMT promoter methylation (40.8% vs 38.4%). Notably, 50.7% of AYA PCNSLs were associated with HIV/AIDS, vs only 7.1% in adults (p< 0.001).

CONCLUSIONS

The distribution, epidemiology, and survival outcomes of primary brain tumors in the AYA population are distinct from their pediatric and adult counterparts. Notably, AYA infiltrative gliomas were more often of lower grade than adults and AYA PCNSL were far more likely to be associated with HIV/AIDS. Primary brain tumors in AYA patients require specialized management.
EPID-19. CONDUCTING A NATIONWIDE BRAIN TUMOR EPIDEMIOLOGY STUDY IN AN LMIC: A MULTI-INSTITUTIONAL EXPERIENCE
Authors: Baig Erum , Shah Mashal , Bajwa Mohammad Hamza , Laghari Altaf Ali , Akhunzada Naveed Zaman , Bin-Anis Saad , Khalid Usman , Qadeer Namra , Lutfi Areeb , Tahir Izza , Bajwa Rameen , Rashid Huzaifa , Sadia Haleema , Ghazi Kinzah , Gillani Mishal , Siddiqi Sameen , Enam Syed Ather
Published: November 2021

Very little research has been conducted on brain tumor epidemiology in Pakistan and a few studies that do exist provide regional data only. Conducting population based epidemiological studies in low-and-middle income countries (LMICs) like Pakistan can be particularly challenging due to limited resources, poor clinical and research infrastructure, unreliable or incomplete hospital records and a lack of standardization across the health care system. Population-wide studies and registries play an important role in cancer epidemiology and can help identify the current magnitude of cancer burden and its likely future evolution, allowing for better planning of prevention, diagnosis, management, and rehabilitation. This paper describes our experience in designing and conducting Pakistan Brain Tumor Epidemiology Study (PBTES), a first-ever nationwide study carried out to assess the distribution of brain tumors in Pakistan. In addition to the aforementioned obstacles, we were also faced with the global health crisis caused by the COVID-19 pandemic and had to promptly adjust our study accordingly. Other investigators conducting epidemiological studies in LMICs with similarly challenging and constricting settings could benefit from our experiences.
EPID-20. THE RISING INCIDENCE AND PREVALENCE OF BRAIN TUMOURS: A CANADIAN EPIDEMIOLOGICAL STUDY
Authors: Voisin Mathew , Sasikumar Sanskriti , Mansouri Alireza , Zadeh Gelareh
Published: November 2021

BACKGROUND

Primary malignant brain tumours account for over one third of all brain tumours and are associated with high morbidity and mortality. The purpose of this paper is to estimate the rate and trends of incidence and prevalence for primary malignant CNS tumours in Canada from 1992 to 2017.

METHODS

An epidemiological study using publicly available data from Statistics Canada: Canadian Cancer Registry (CCR) from 1992 to 2017 for all of Canada was conducted. Incidence and prevalence per 100,000, age-standardized incidence, and age-standardized prevalence per 100,000 person-years of primary malignant CNS tumours were calculated and stratified by sex and age: pediatric (0-19), adult (20-64), and elderly ( >64) populations.

RESULTS

During the study period, incidence and prevalence increased by 27.3% and 28.8%, respectively. Males accounted for 56% of all diagnoses and experienced decreased survival compared to females one year after diagnosis (p-value = 0.04). Age-standardized rates of incidence and prevalence were highest in elderly populations.

CONCLUSIONS

Overall, the incidence of primary malignant CNS tumours has increased from 1992 to 2017 with males and the elderly disproportionately affected. Increased healthcare resources and awareness are needed to better identify and deliver evidence-based care for these patients.
EPID-25. DISTANCE TRAVELED FOR BRAIN TUMOR CARE IN PAKISTAN: AN LMIC PERSPECTIVE
Authors: Bajwa Mohammad Hamza , Shah Mashal , Baig Erum , Tahir Izza , Ghazi Kinzah , Bajwa Rameen , Laghari Altaf Ali , Bin-Anis Saad , Akhunzada Naveed Zaman , Gilani Jaleed , Jawed Noyan , Khalid Usman , Qadeer Namra , Lutfi Areeb , Rashid Huzaifa , Sadia Haleema , Gillani Mishal , Consortium Pakistan Brain Tumor , Siddiqi Sameen , Enam Syed Ather
Published: November 2021

INTRODUCTION

Global oncology development within LMICs (low- and middle-income countries) requires bridging gaps in healthcare systems. Brain tumor care in Pakistan is currently sparse and concentrated in urban centers. Distance traveled to a hospital dictates a patient’s access to care, neurosurgical access, and continuity of care through adjuvant chemoradiotherapy and primary care providers can be disrupted if patients cannot overcome the barriers due to extensive distances traveled.

METHODS

Data was collected as part of the Pakistan Brain Tumor Epidemiology Study (PBTES) regarding patients with brain tumors who underwent surgical procedures in 2019 at private and public major neurosurgical centers across Pakistan. Using patient addresses, we used a mapping software to calculate the distance traveled by each patient to the primary hospital. Analysis was done using appropriate statistical methods.

RESULTS

Out of 2403 patients, the mean distance traveled across the country was 240 km. The longest distance traveled within Pakistan was from Skardu to Karachi (2002 km) for resection of a pituitary adenoma (28 hours via car). Only 48% of patients were able to reach their primary hospital within 50 km. 52% of patients had to travel more than 50 km, and 18% had to travel upwards of 500 km to reach their primary hospital. Additionally, 101 patients traveled to Pakistan from other countries for brain tumor surgery (98 patients from Afghanistan [mean distance traveled: 723.6 km], 3 patients from Syria, Oman, and Sudan).

CONCLUSION

Prior studies have described a cut-off of 50 km as an acceptable limit for distance from the primary hospital in cancer patients for optimal follow-up and outcomes, which is achieved by only 48% of brain tumor patients in Pakistan. Most patients have poor access to surgical care for brain tumors, further compounded by repeat traveling for follow-ups and chemoradiotherapy.
IMMU-06. COMBINATORIAL IMMUNE CHECKPOINT INHIBITORS FOR TARGETED INTRATUMORAL DELIVERY IN GBM
Authors: Sanders Stephanie , Herpai Denise , Debinski Waldemar
Published: November 2021

Glioblastoma (GBM) is an immunologically cold tumor. Using single cell sequencing of CD45+ cells we confirmed that T cells are present within GBM samples. These T cells are positive for exhaustion markers such as LAG3 and TIGIT, as well as CTLA4 and PD1 checkpoint receptors. Modulating T cell activity through use of immune checkpoint inhibitors (ICIs) has shown efficacy in the treatment of a variety of solid tumors, and the combination of anti-CTLA4 and anti-PD1 ICIs has shown increased efficacy over use of a single therapeutic. Additionally, targeting ICIs to the tumor cells may increase efficacy of this treatment. We therefore constructed a combinatorial ICI redirected to GBM via interleukin 13 receptor alpha 2 (IL13RA2), a receptor over-expressed on the majority of GBM cells but not normal brain. The first component of the construct, labeled with a histidine tag, targets CTLA4 while the second component, tagged with a StrepII tag, targets PD1. The tags added to the constructs will allow for purification of a combinatorial heterodimer simultaneously targeting PD1, CTLA4 and IL13RA2. We purified individual components via fast protein liquid chromatography (FPLC) using a proteinG column followed by a HisTrap or StrepTrap column. We obtained a recombinant, targeted multivalent ICI at > 95% purity. We found that these constructs are able to bind their target receptors via ELISA in which the Kd values ranged from picomolar to low nanomolar range. Additionally, our constructs bind their target on live cells by flow cytometry. We next designed a heterodimeric construct which can combinatorially target CTLA4 and PD1 while also directing the ICI therapy to GBM. These constructs in conjunction with other immune stimulants like cytotoxic therapies are intended to facilitate the interaction between T cells and GBM tumor cells directly in a tumor microenvironment.
IMMU-09. HUMAN MICROBIOTA INFLUENCE THE EFFICACY OF IMMUNOTHERAPY IN A MOUSE MODEL OF GLIOBLASTOMA
Authors: Dees Kory , Koo Hyunmin , Humphreys James , Hakim Joseph , Crossman David , Crowley Michael , Nabors L Burt , Benveniste Etty , Morrow Casey , McFarland Braden
Published: November 2021

Although immunotherapy works well in glioblastoma (GBM) pre-clinical mouse models, the therapy has unfortunately not demonstrated efficacy in humans. In melanoma and other cancers, the composition of the gut microbiome has been shown to determine responsiveness or resistance to immune checkpoint inhibitors (anti-PD-1). Most pre-clinical cancer studies have been done in mouse models using mouse gut microbiomes, but there are significant differences between mouse and human microbial gut compositions. To address this inconsistency, we developed a novel humanized microbiome (HuM) model to study the response to immunotherapy in a pre-clinical mouse model of GBM. We used five healthy human donors for fecal transplantation of gnotobiotic mice. After the transplanted microbiomes stabilized, the mice were bred to generate five independent humanized mouse lines (HuM1-HuM5). Analysis of shotgun metagenomic sequencing data from fecal samples revealed a unique microbiome with significant differences in diversity and microbial composition among HuM1-HuM5 lines. Interestingly, we found that the HuM lines responded differently to anti-PD-1. Specifically, we demonstrate that HuM2 and HuM3 mice are responsive to anti-PD-1 and displayed significantly increased survival compared to isotype controls, while HuM1, HuM4, and HuM5 mice are resistant to anti-PD-1. These mice are genetically identical, and only differ in the composition of the gut microbiome. In a correlative experiment, we found that disrupting the responder HuM2 microbiome with antibiotics abrogated the positive response to anti-PD-1, indicating that HuM2 microbiota must be present in the mice to elicit the positive response to anti-PD-1 in the GBM model. The question remains of whether the “responsive” microbial communities in HuM2 and HuM3 can be therapeutically exploited and applicable in other tumor models, or if the “resistant” microbial communities in HuM1, HuM4, and HuM5 can be depleted and/or replaced. Future studies will assess responder microbial transplants as a method of enhancing immunotherapy.
IMMU-11. SELECTIVE ENRICHMENT OF SUPPRESSED IMMUNE CELLS IN THE TUMOR MICROENVIRONMENT CORRELATES WITH ESTABLISHMENT OF DISTINCT IMMUNOLOGIC NICHES IN HUMAN GLIOBLASTOMAS CONTACTING THE LATERAL VENTRICLE
Authors: Bartkowiak Todd , Brockman Asa , Mobley Bret , Mistry Akshitkumar , Barone Sierra , Hayes Madeline , Roe Caroline , Sinnaeve Justine , Leelatian Nalin , Greenplate Allison , Chambless Lola , Thompson Reid , Weaver Kyle , Irish Jonathan , Ihrie Rebecca
Published: November 2021

Glioblastomas (GBM) account for 60% of adult primary brain tumors. With few advances in therapeutics, median overall survival remains 15-months post-diagnosis. Immunotherapies may provide therapeutic benefit in GBM patients; however, no predictive immune features currently inform therapeutic stratification in GBM. We have shown that, independently of known prognosticators, radiographic tumor contact with the lateral ventricle (C-GBM) correlates with 7-months worse prognosis compared to patients with ventricle non-contacting GBM (NC-GBM). This study sought to characterize the GBM immune microenvironment and identify targetable mechanisms of immunosuppression correlating with worse outcomes in C-GBM. Primary glioblastoma specimens were resected in accordance with the Declaration of Helsinki (IRB #131870). Twelve patients presented with C-GBM and thirteen with NC-GBM. Machine learning tools applied to mass cytometry data characterized tumor-infiltrating immune populations and identified biomarkers correlating with C-GBM and patient survival. C-GBM tumors were enriched in blood-derived macrophages compared to NC-GBM (19 ± 8% vs. 6 ± 2%; p< 0.001) and depleted in lymphocytes (2.9 ± 1% vs. 7.6 ± 2%; p< 0.001) and tissue-resident microglia (1.8 ± 0.3% vs. 7 ± 3%; p< 0.001). Further, T cells in C-GBM co-expressed the checkpoint receptors PD-1 and TIGIT, suggesting acute T cell exhaustion. Multiplex immunohistochemistry (mxIHC) on matched FFPE tissue provided spatial context to risk-stratifying immune populations, and defined structured immunological niches within the TME. Macrophage-tumor niches were most common (36%), followed by T cell-microglia-tumor niches (26%). Within niches, T cell-T cell interactions were more prevalent (log odds ratio = 0.90) whereas T cell-macrophage interactions were less prevalent (log odds ratio = -1.61). These findings suggest that factors within the periventricular space may influence antitumor immunity within tumors, and identify clinically targetable immune biomarkers in glioblastoma. Notably, radiologic assessment of lateral ventricle contact by standard-of-care MRI may guide clinical trial design for immunotherapies in neuro-oncology.
IMMU-15. INVESTIGATING CD8 T CELL EXHAUSTION STATES GLIOBLASTOMA
Authors: Polania Jessica Waibl , Tomaszweski William , Hoyt-Miggelbrink Alexandra , Woroniecka Karolina , Fecci Peter
Published: November 2021

BACKGROUND

Glioblastoma (GBM) is the most common primary brain cancer in adults and remains universally lethal. Median survival remains a bleak 15-17 months from time of diagnosis, and current immunotherapeutic efficacy continues to be hindered by the robust immunosuppression present in the GBM microenvironment. T cells, critical for tumor clearance, are particularly affected, and many take on a functionally exhausted phenotype within the tumor. Importantly, two exhaustion states, progenitor and terminal, have been identified in models of chronic infection and cancer. This distinction is particularly relevant, as progenitor exhausted T cells can respond favorably to immune checkpoint blockade, while terminally exhausted T cells are resistant. To date, the dynamics and characteristics of these exhausted populations in GBM remain unclear.

RESULTS

In an orthotopic murine model of GBM, progenitor and terminal exhausted CD8 T cells were identified by flow cytometry as PD1+SLAMF6+ and PD1+TIM3+, respectively. Using a time-course approach, we detected progenitor exhaustion by day 8 in the tumor, but not in draining lymph nodes. Additionally, we show that the frequency of progenitor exhaustion is highest during early tumor progression, while terminal exhaustion is the most abundant in more advanced tumors ( >14 days). Functional differences between subsets were evaluated via intracellular staining of IFNγ, TNFα, granzyme B, and Ki67. Terminally exhausted T cells displayed higher cytotoxic molecule expression than progenitor exhausted T cells, similar to what has been documented in melanoma models.

CONCLUSIONS

Our findings identify T cell exhaustion subsets within GBM that require further investigation and may be relevant to overcome current barriers to immunotherapeutic efficacy.
IMMU-27. LONG TERM STABILIZATION OF RECURRENT HIGH-GRADE GLIOMA WITH PD-1 INHIBITOR PEMBROLIZUMAB IN TWO CASES
Authors: Moldenhauer Matthew , Du Steven , Fu Dan , Myung Joon , Bota Daniela , Kong Xiao-Tang
Published: November 2021

INTRODUCTION

Despite PD-1 inhibition having success in many cancers, it has uncertain effects in brain tumors. We report two cases of recurrent high-grade gliomas that have remained stable for over one year since starting pembrolizumab.

CASE REPORTS

Case 1: A 59-year-old male was diagnosed with glioblastoma (GBM) without MGMT methylation or IDH mutation in late 2018 after surgery. He received radiation and temozolomide (TMZ) followed by adjuvant TMZ before tumor progression. He underwent second tumor debulking with recurrent GBM on pathology with negative PD-L1 expression. He started carboplatin. Progression was noticed after 7 to 8 cycles. Pembrolizumab was added. Tumor was stabilized. Carboplatin was completed after total 12 cycles and the patient has continued single agent of pembrolizumab for more than one year with stable brain MRIs. The patient has survived for 24 months since recurrence and 30 months since diagnosis. Case 2: A 53-year-old male had a brain tumor discovered on MRI in 2012 and received no treatment until resection in 2014. In 2016, he underwent second tumor debulking and was diagnosed with anaplastic oligodendroglioma with negative PD-L1 expression. He received radiation followed by PCV regimen. 17 months since diagnosis, he had first tumor progression on PCV. TMZ was started. 22 months since diagnosis, bevacizumab was initiated due to further growth. 33 months since diagnosis, pembrolizumab was added due to new lesions after 12-months of bevacizumab therapy. His tumor was stabilized. Bevacizumab was eventually discontinued. He has continued single agent pembrolizumab for 6 months so far. His tumor has been stable for 22 months since starting pembrolizumab. Survival has been 38 months from first recurrence and 7 years since tissue diagnosis.

DISCUSSION

These cases demonstrate the potential effects of anti-PD-1 immunotherapy in stabilizing recurrent high-grade glioma with combination of other treatment agents followed by single agent as maintenance therapy.
IMMU-39. EVALUATION OF CD317-TARGETING CAR T CELLS AS A NOVEL IMMUNOTHERAPEUTIC STRATEGY AGAINST GLIOBLASTOMA
Authors: Hänsch Lena , Peipp Matthias , Myburgh Renier , Silginer Manuela , Weiss Tobias , Gramatzki Dorothee , Vasella Flavio , Manz Markus , Weller Michael , Roth Patrick
Published: November 2021

Glioblastoma remains one of the deadliest cancers despite aggressive treatment, which is why novel therapeutic approaches are urgently needed. Chimeric antigen receptor (CAR) T cell therapy has demonstrated significant success in the field of hematological malignancies. However, treating glioblastoma with this type of therapy is more difficult for several reasons such as the lack of suitable target antigens. Here, we generated a second-generation CAR construct targeting the transmembrane protein CD317 (BST-2, HM1.24), which is expressed by human glioma cell lines in vitro as well as in vivo. We demonstrate strong anti-glioma activity of CD317-CAR T cells against different glioma target cells with varying CD317 expression levels. Glioma cells harboring a CRISPR/Cas9-mediated CD317 knockout were not susceptible for these CAR T cells, demonstrating their target antigen-specificity. CD317 is also expressed on T cells and transduction with a CD317-directed CAR impaired expansion of T cells due to residual CD317 expression and subsequent fratricide. Therefore, we silenced CD317 in the transduced T cells by co-expressing the CAR construct with a specific shRNA, which significantly increased the viability, proliferation and cytotoxicity of the CAR T cells. Finally, we observed strong anti-glioma activity of CD317-CAR T cells in clinically relevant orthotopic xenograft glioma mouse models resulting in prolonged survival of CAR T cell-treated animals. Taken together, these data reveal a promising role of CD317 as a novel target for CAR T cell therapy in glioblastoma and warrant further evaluation of this strategy in clinical neuro-oncology.
IMMU-40. IMMUNE PROFILING OF MATCHED PRIMARY AND RECURRENT GLIOBLASTOMA TUMORS IDENTIFIED CD64 AS A NEGATIVE PREDICTOR FOR SURVIVAL
Authors: Shekarian Tala , Ritz Marie-Françoise , Martins Tomàs , Schmassmann Philip , Hutter Gregor
Published: November 2021

BACKGROUND

To target tumor-induced immune evasion mechanisms of glioblastoma for clinical research, we aimed at characterizing the immunological changes in patient-matched treatment-naïve and recurrent GBM samples.

MATERIAL AND METHODS

Proteins and total RNA were extracted from 15 patient-matched treatment-naïve (primary) and recurrent GBM fresh frozen tumor samples. The expression of genes involved in brain immune responses were compared using Nanostring panels encompassing Cancer and Neuroinflammation genes. Correlation analysis using log2-transformed patient-matched recurrent/primary expression ratio (log2(P/R)) and clinical outcome data (time to relapse and overall survival (OS)) was conducted. Proteomic was conducted to compare total protein expressions. Moreover, immunostaining was performed on a tissue microarray of matched tumor samples to visualize CD64+ cells, CD47+ tumor cells and microglia in order to assess quantitative transcriptome of these specific cell types using GeoMX technology. Functional assays are designed for deciphering phagocytosis induction by factors produced by primary and recurrent tumors.

RESULTS

Genes significantly differentially expressed between primary and recurrent tumors revealed “Antigen presentation” and “Microglia Pathogen Phagocytosis” as the most significant pathways enriched in recurrent tumors. Considering individual genes, a strong negative correlation (R2>0.4) between log2(R/P) and time to relapse and OS was found for 2 genes, FCGR1A (CD64) and CD47. We observed that only CD64 expression levels in recurrent samples also negatively correlated with OS. CD64 and CD47 proteins were quantified by proteomic analysis and log2 (R/P) of their levels also negatively correlated with time to relapse. Immunostaining revealed numerous CD64-positive cells in tumor biopsies resembling bushy or amoeboid microglia.

CONCLUSION

Upregulation of CD64 and CD47 expressions in recurrent GBM was identified as a negative predictor for time to relapse and OS. This suggests an important role of CD64 and CD47 and related inflammation dysregulation in tumor resistance and regrowth. Interfering with CD64-induced functions may represent a novel therapeutic option for GBM.
IMMU-41. NEOADJUVANT PD-1 BLOCKADE INDUCES T CELL AND CDC1 ACTIVATION BUT FAILS TO OVERCOME THE IMMUNOSUPPRESSIVE TUMOR ASSOCIATED MACROPHAGES IN RECURRENT GLIOBLASTOMA
Authors: Lee Alexander , Sun Lu , Mochizuki Aaron , Reynoso Jeremy , Orpilla Joey , Chow Frances , Kienzler Jenny , Everson Richard , Nathanson David , Liau Linda , Cloughesy Timothy , Hugo Willy , Prins Robert
Published: November 2021

In a small phase I clinical trial, neoadjuvant anti-PD-1 (neo-aPD1) improved survival in glioblastoma patients (GBM) and was associated with increased interferon-γ-related gene expression and an associated decrease in cell cycle-related gene expression in the tumor. Despite this, neo-aPD1 was not curative. To better understand how neo-aPD1 alters the GBM tumor microenvironment and to discover new therapeutic axes, we used CyTOF and single-cell RNAsequencing to analyze the tumor-infiltrating immune populations of 70 GBM patients, 20 of whom had received neo-aPD1. In patients treated with neo-aPD1 the proportion and number of tumor-infiltrating T cells increased and these T cells had increased expression of the cytokines CCL5 and XCL1, which promote dendritic cell migration. Among the infiltrating T cells was a population of progenitor exhausted CD8+ T cells expressing the genes TCF, SLAM6, CCR7, IL7R, and GZMB. Single-cell TCR analysis revealed that these CD8+ T cells arose from a population of early activated, cytotoxic T cells that had expanded in the peripheral blood and trafficked into the tumor. Within the tumor-infiltrating myeloid cells, we found that neo-aPD1 upregulated genes in the interferon-γ response pathways; namely genes related to T cell trafficking and immune suppression, such as CD274 (PD-L1), TREM2, GPNMB, and IL10, indicating a maladaptive response by some myeloid cells to the immune response triggered by neo-aPD1. Finally, we identified a new migratory and interferon-γ activated tumor-infiltrating conventional dendritic cell population that was increased with neo-aPD1 and that notably expressed XCR1, the receptor for XCL1. Additionally, our results provide future basis to study if modalities that enhance the T cell:DC axis or that inhibit the inhibitory myeloid populations may improve survival in patients with GBM when used in conjunction with neo-aPD1. In sum, we characterized the immune landscape in GBM and how it changes with neo-aPD1 at single cell resolution.
IMMU-42. OPTIMIZING IMMUNOTHERAPY FOR GLIOMA USING CYTOKINE-ACTIVATED NATURAL KILLER CELLS
Authors: Kerstetter-Fogle Amber , Otegbeye Folashade , Soler David , Harris Peggy , Raghavan Alankrita , Sloan Andrew
Published: November 2021

INTRODUCTION

Glioblastoma multiforme (GBM) is the most common primary central nervous system malignancy associated with a 12-15 month survival after surgery and radio-chemotherapy. Utilizing adoptive cellular immunotherapy using natural killer (NK) cells has developed over the past two decades for a variety of hematologic malignancies. This approach in solid malignancies is limited by questions of cell dose versus tumor burden, insufficient tumor infiltration, and a tumor microenvironment that suppresses NK cell function.

METHODS

We isolated NK cells from healthy volunteers and activated them using IL-2, -15, -12, -18, then perform cytotoxic assays in the presence of glioma stem cells. We also tested the efficacy of the NK cells with intracranial delivery in a pre-clinical murine model of glioma. We tested various concentrations of IL-2 and IL-15 on the cytokine culture platform.

RESULTS

In this study, we demonstrate human NK cells, activated using a cytokine cocktail of interleukins-2, -15, -12, and -18, exert strong cytotoxic events against glioma cell lines. To further examine the efficacy of activated NK cells in vitro, we utilized intracranially xenografted glioma lines and demonstrated a survival benefit with tumor bed injections of these cytokine-activated NK cells (p=0.0089). We were able to confirm that NK cells cultured with low doses (200u IL2; 50ng/ml IL15) of both cytokines are just as effective as higher doses. This is important, as in vivoexhaustion of NK cells stimulated with high doses of either cytokine has been well validated. We also found that low-dose irradiation (4Gy) of glioma cells prior to co-culture with cytokine-activated NK cells promoted increased targeted glioma cell killing within 4 hours(32% cell killing).

CONCLUSIONS

These findings suggest that in a clinical study, injection of cytokine-activated NK cells into the glioblastoma tumor bed could be used as adjuvant treatment following either stereotactic radiation or surgical resection.
IMMU-45. COMBINATION OF EGFRVIII CAR T-CELL THERAPY AND PARACRINE GAM MODULATION FOR THE TREATMENT OF GBM
Authors: Martins Tomás A , Ritz Marie-Françoise , Shekarian Tala , Schmassmann Philip , Kaymak Deniz , Bicvic Valentina , Hutter Gregor
Published: November 2021

The GBM immune tumor microenvironment mainly consists of protumoral glioma-associated microglia and macrophages (GAMs). We have previously shown that blockade of CD47, a ‘don't eat me’-signal overexpressed by GBM cells, rescued GAMs' phagocytic function in mice. However, monotherapy with CD47 blockade has been ineffective in treating human solid tumors to date. Thus, we propose a combinatorial approach of local CAR T cell therapy with paracrine GAM modulation for a synergistic elimination of GBM. We generated humanized EGFRvIII CAR T-cells by lentiviral transduction of healthy donor human T-cells and engineered them to constitutively release a soluble SIRPγ-related protein (SGRP) with high affinity towards CD47. Tumor viability and CAR T-cell proliferation were assessed by timelapse imaging analysis in co-cultures with endogenous EGFRvIII-expressing BS153 cells. Tumor-induced CAR T-cell activation and degranulation were confirmed by flow cytometry. CAR T-cell secretomes were analyzed by liquid chromatography-mass spectrometry. Immunocompromised mice were orthotopically implanted with EGFRvIII+ BS153 cells and treated intratumorally with a single CAR T-cell injection. EGFRvIII and EGFRvIII-SGRP CAR T-cells killed tumor cells in a dose-dependent manner (72h-timepoint; complete cytotoxicity at effector-target ratio 1:1) compared to CD19 controls. CAR T-cells proliferated and specifically co-expressed CD25 and CD107a in the presence of tumor antigen (24h-timepoint; EGFRvIII: 59.3±3.00%, EGFRvIII-SGRP: 52.6±1.42%, CD19: 0.1±0.07%). Differential expression analysis of CAR T-cell secretomes identified SGRP from EGFRvIII-SGRP CAR T-cell supernatants (-Log10qValue/Log2fold-change= 3.84/6.15). Consistent with studies of systemic EGFRvIII CAR T-cell therapy, our data suggest that intratumoral EGFRvIII CAR T-cells were insufficient to eliminate BS153 tumors with homogeneous EGFRvIII expression in mice (Overall survival; EGFRvIII-treated: 20%, CD19-treated: 0%, n= 5 per group). Our current work focuses on the functional characterization of SGRP binding, SGRP-mediated phagocytosis, and on the development of a translational preclinical model of heterogeneous EGFRvIII expression to investigate an additive effect of CAR T-cell therapy and GAM modulation.
IMMU-49. DYNAMIC CHANGES AND PROGNOSTIC VALUE OF PERIPHERAL BLOOD LYMPHOCYTE SUBSETS IN INTRACRANIAL GERM CELL TUMORS
Authors: Wang Hairong , Guo Cheng-Cheng , Chen Hongyu , Qun-ying Yang , Chen Zhong-ping
Published: November 2021

OBJECTIVE

This study was designed to retrospectively analyze the dynamic changes of peripheral blood lymphocyte subsets and prognosis among patients with intracranial germ cell tumors.

METHODS

A total of 150 intracranial germ cell tumors patients diagnosed between June 2011 till November 2019 were retrospectively investigated. Peripheral blood total T lymphocytes (CD3+) percentage, T helper/inducible lymphocytes(CD3+CD4+)percentage, T inhibitory/toxic lymphocytes (CD3+CD8+) percentage, B lymphocyte (CD19+) percentage, NK lymphocyte (CD3/CD16+CD56+) percentage, regulatory T cells (CD4+CD25+,CD8+CD25+), and T helper/toxic lymphocyte ratio (CD4+/CD8+ ratio) were quantified by flow cytometry analysis. Clinical information was extracted from the database in Sun Yat-sen University Cancer Center and survival data was confirmed through outpatient visits and telephone follow-up.

RESULTS

T lymphocytes population was increased after anti-tumor treatment, with significant difference of total T lymphocytes (CD3+), inhibitory/toxic T cells (CD3+CD8+) and regulatory T cells (CD4+CD25+ and CD8+CD25+), (p=0.008, p=0.000, p=0.008 and p=0.001 respectively), while B lymphocytes(CD19+) decreased after chemotherapy(p=0.003). The dynamic levels of T lymphocyte and B lymphocyte subpopulation after chemotherapy did not present significant differences between gender, age, and locations of tumors (p >0.05), except CD4+CD25+ T cells in younger children (age< 16 years older) increased significantly than the elder (age >16), p=0.04. Patients with increased CD19+ B cells presented significant suboptimal outcomes compared with the no increased (p=0.024). Similarly, increased CD3+ T cells, CD3+CD8+ T cells, CD4+CD25+ T cells reduced the risk of death (p=0.006, p=0.019, p=0.042 respectively). Multivariate Cox Regression analysis showed: increased CD19+ B cells, p=0.04, HR=1.688, 95%CI=1.025-2.779.

CONCLUSION

After anti-tumor treatment, cell-mediated immunity activated, enhanced, and dominated in anti-tumor response. An increased level of CD19+ subsets was an independent predictor for inferior overall survival. Systemic circulating T cells immunity played an important role and mediating antitumor responses may pave the road for new immunity strategies.