bluuebunny/crossref_metadata_2025 huggingface dataset:
EXTH-35. SYNERGISTIC EFFECT OF TARGETING THIOREDOXIN REDUCTASE (TRX1) AND DEPLETION OF GLUTATHIONE SYSTEM (GSH) IN GLIOBLASTOMA STEM CELLS
Authors: Jamali Fatemeh , Daniel Paul , Petrecca Kevin , Abdulkarim Bassam , Sabri Siham
Published: December 2020

Glioblastoma (GBM), the most common and advanced malignant primary brain tumor in adults remains incurable. GBM tumor recurrence occurs within a short time reflecting the failure to eradicate chemo-radioresistant GBM stem cells (GSCs). GSCs alter the redox system including Thioredoxin (Trx) and glutathione (GSH) systems to counteract increased reactive oxygen species (ROS). We previously showed the role of O6-methylguanine-DNA methyltransferase (MGMT) in response to PRIMAMET, a drug that targets the TP53 tumor suppressor gene and decrease Thioredoxin reductase1 (TRxR1) levels and further identified a positive relationship between MGMT and TrxR1 in established GBM cell lines isogenic for MGMT. Auranofin (Au), an orally available ROS-inducing FDA-approved drug is a potent irreversible inhibitor of TrxR1. The effect of Au on GSCs and the potential relationship between TrXR1, MGMT and p53 specifically in GSCs remain unknown. We hypothesized that increased ROS levels in GSCs might affect their drug resistant phenotype. we investigated the cytotoxic effects of Au on GSCs with known MGMT and P53 status and the mechanisms underlying these effects. Our results suggest that Au exerts strong cytotoxic effects in GSCs within a micromolar range. These effects were associated with increased ROS levels, decreased TrXR1, MGMT, phosphorylation of ERk1/2, activation of p53 and increased apoptosis, we also used a knockdown strategy to assess the role of p53 and showed that increased sensitivity to Au for p53-knockdown. We showed the role of ROS in response to Au using ROS inducer L-Buthionine Sulfoxamine (L-BSO), a GSH inhibitor, and ROS scavenger N-Acetylcysteine (NAc). L-BSO combined with Au drastically decreased the IC50 within a nanomolar range suggesting the crucial role of both Trx and GSH systems in GSCs redox balance. Increased ROS with concomitant GSH depletion using L-BSO might circumvent drug-induced oxidative stress and overcome drug resistance in MGMT-positive and negative GSCs
EXTH-54. ENHANCED SENSITIVITY OF HUMAN GLIOMA CELLS FOR TEMOZOLOMIDE (TMZ) BY COMBINING THERAPY WITH HEAT SHOCK PROTEIN 90
Authors: Sharma Pratibha , Mahadevan Lakshmi Shree K , Argall Aaron , Xu Jihong , Sampath Deepa , Puduvalli Vinay
Published: December 2020

BACKGROUND

Heat-shock protein 90 (HSP90) is a molecular chaperone involved in the conformational maturation of many client proteins that regulate cell proliferation, survival, and apoptosis. Due to the limited solubility of natural Hsp90 inhibitors, synthetic inhibitors with a more potent impact are being developed. In this study we examined the biological activity of a potent synthetic small molecule Hsp90 inhibitor, SNX-5422 (PF-04929113)and assessed its ability of to inhibit the growth of glioma and to synergize with temozolomide. We also examined the ability of SNX-5422 to cross the blood brain barrier (BBB) and to achieve target inhibition in vivo.

METHODS

Using a combination of in vitro techniques, the effect of SNX-5422 on the biological impact and HSP90 client protein signaling were studied in glioma lines and patient-derived glioma stem like cells. Its efficacy as a single agent or in combination with TMZ was also assessed in vitro. To assess SNX-5422 ability to cross blood brain barrier, brain and plasma pharmacokinetics was performed in non-tumor bearing mice.

RESULTS

SNX-5422 exhibited potent growth inhibition in both glioma cells and GSCs with an IC50 range of 100-500nM, and inhibited pro-survival signal kinases, phospho-Akt, p-ERK1/2 and p-S6 following treatment in GSC262 and GSC811. This was accompanied by accumulation of apoptotic cells following SNX-5422 exposure. Combination studies with TMZ showed a synergestic impact on glioma cell proliferation. Pharmacokinetics studies showed a significant drug penetrance into the intact brain further supported by elevated levels of HSP70 (molecular maker for HSP90 inhibition) by IHC.

CONCLUSIONS

SNX-5422 is effective in downregulating Hsp90 client proteins required for glioma cell survival. In addition, SNX-5422 inhibits tumor growth by promoting apoptosis through modulation of several key signaling pathways and sensitizes glioma cells to TMZ. Given also that SNX-5422 crosses BBB, it warrants further investigation as a clinical agent for treatment of gliomas.
EXTH-60. CHARACTERIZATION OF THE ONCOLYTIC ADENOVIRUS DELTA-24-RGD AS THERAPEUTIC AGENT FOR THE TREATMENT OF THE PEDIATRIC EMBRYONAL BRAIN TUMORS AT/RT AND CNS-PNET
Authors: Garcia-Moure Marc , González-Huarriz Marisol , Laspidea Virginia , Marrodán Lucía , Gomez-Manzano Candelaria , Fueyo Juan , Patiño-García Ana , Alonso Marta M
Published: December 2020

Atypical teratoid/rhabdoid tumors (AT/RTs) and primitive neuroectodermal tumors of the central nervous system (CNS-PNET) are rare pediatric brain tumors affecting mainly infants and young children. Current therapies for these diseases are inefficient and often cause severe side effects; thus, new therapeutic strategies are urgently needed. Here, we evaluate the anti-tumor effect of the Delta-24-RGD oncolytic adenovirus in preclinical models of CNS-PNET and AT/RT. In vitro, the virus infects and efficiently replicates in different cell culture models of AT/RT and CNS-PNET, inducing a dose-dependent cytotoxic effect (IC50 values below 1 PFU/cell) and the release of immunogenic cell death stimuli. Survival studies in mice bearing orthotopic AT/RTs (supra and infratentorial) or CNS-PNETs demonstrate the therapeutic benefit of a single Delta-24-RGD intratumoral administration (107 or 108 PFU). In virus-treated mice, median overall survival increased between 50–300% (depending on the model), obtaining up to 60% of long-term survivors. Intra-ventricular injection of Delta-24-RGD hinders the development of secondary AT/RT spinal lesions. Moreover, response to the treatment was observed even delaying viral administration up to 30 days after tumor engraftment; thus, demonstrating therapeutic benefit even in animals challenged with large well-established tumor masses. The effect of the oncolytic virus was also assessed in an immunocompetent environment using hCD34+ humanized NSG-SGM3 mice. In this model, Delta-24-RGD significantly extended overall survival (from 23 to 24 days in AT/RT model and from 28 to 55 days in CNS-PNET) with no signs of toxicity associated with inflammation. Immunophenotyping of Delta-24-RGD treated tumors by flow cytometry, RNAseq and multiplexed histology revealed that Delta-24-RGD contributes to generate a pro-inflammatory status, allowing the infiltration of immune cells and the trigger of an antitumor immune response. In conclusion, these results demonstrate that Delta-24-RGD could be a feasible therapeutic choice for AT/RT and CNS-PNET, paving the way for upcoming clinical trials.
EXTH-64. SMALL GTPASES IN MENINGIOMAS: PROLIFERATION, MIGRATION, SURVIVAL, POTENTIAL TREATMENT AND INTERACTIONS
Authors: Kesseler Christoph , Kahr Julian , Waldt Natalie , Stroscher Nele , Liebig Josephine , Angenstein Frank , Kirches Elmar , Mawrin Christian
Published: December 2020

PURPOSE

To evaluate the role of the small GTPases RhoA, Rac1 and Cdc42 in meningiomas as therapeutic targets and their interactions in meningiomas.

EXPERIMENTAL DESIGN

We analyzed expression of GTPases in human meningioma samples and meningioma cell lines of various WHO grades. Malignant IOMM-Lee meningioma cells were used to generate shRNA mediated knockdowns of GTPases RhoA, Rac1 or Cdc42 and to study knockdown effects on proliferation and migration, as well as analysis of cell morphology by confocal microscopy. The same tests were used to investigate effects of the two inhibitors Fasudil and EHT-1864 of malignant IOMM-Lee, KT21 and benign Ben-Men cells and the effects of these drugs on IOMM-Lee knockdown cells. The effects of GTPase knockdowns and Fasudil treatment were studied in terms of overall survival by intracranial xenografts of mice. Potential interactions of GTPases regarding NF2, mTOR and FAK-Paxillin were examined.

RESULTS

Small GTPases were upregulated in meningiomas of higher tumor grades. Reduced proliferation and migration could be achieved by GTPase knockdown in IOMM-Lee cells. Additionally, the ROCK-inhibitor Fasudil and Rac1-inhibitor EHT-1864 reduced proliferation in different meningioma cell lines and reduced proliferation and migration independent of GTPase knockdowns/status. Moreover, overall survival in vivo could also be increased by knockdowns of RhoA and Rac1 as well as Fasudil treatment. GTPase expression was affected dependent on the NF2 status but effects were not very distinct, indicating that NF2 is not strongly involved in GTPase regulation in meningiomas. In terms of mTOR and FAK-Paxillin signaling, each GTPase changes those pathways in a different manner.

CONCLUSION

Small GTPases are important effectors in meningioma proliferation and migration in vitro as well as survival in vivo and their inhibition should be considered as potential treatment option.
EXTH-65. USING METHYLATION PROFILES TO GUIDE THE REPURPOSING OF CHEMOTHERAPIES AGAINST HIGH-RISK MENINGIOMAS
Authors: Tran Anh , Scholtens Denise , Zhang Lyndsee , Pokorny Jenny , Baran Aneta , Sahm Felix , Aldape Kenneth , James Charles , Horbinski Craig
Published: December 2020

Meningioma is the most common primary brain tumor with nearly thirty thousand new cases in the US every year. While most meningiomas grow slowly, hence categorized as benign, they can still impact brain structures and result in disability or lethality. Currently, there is no widely accepted chemotherapy for meningioma, 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 identified associations of methylation at individual CpG sites as detected by the Illumina 450k platform with PFS. Subsequently, we 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 PFS (positive hazard ratios (HRs)) and with longer PFS (negative HRs) at FDR-adjusted p < 0.05. Using Cytoscape/Reactome FI app, 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 sixteen meningioma cell lines tested ranged from 0.8nM to 4.4mM, which partially corresponded to the growth rates of these 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.
EXTH-68. STUDY THE SYNERGISTIC EFFECT OF FOCUSED ULTRASOUND AND RADIATION THERAPY FOR BRAIN TUMOR TREATMENT
Authors: Huang Chiungyin , Wei Kuochen
Published: December 2020

The standard treatment of malignant brain tumor is surgical resection followed by adjuvant chemo/radiotherapy. However, in spite of these aggressive treatments, tumor may still recur and resulting in poor survival. In solid tumors, the hypoxia condition presented in most of tumor area may contribute to treatment failure in both adjuvant therapies. It had been proven that systemic delivered oxygen may not sufficient for ionizing radiation to produce cytotoxic effect. A recent study reported using focused ultrasound combined with oxygen-contained microbubbles prior to radiation significantly increased the oxygen content in breast cancers and statistically improved animal survival. Therefore, providing sufficient oxygen in tumor area may be beneficial for radiation therapy. To study the potential role of such strategy for brain tumor treatment, we used focused ultrasound to treat brain tumor bearing animals before radiation therapy. As compared with non-ultrasound treatment groups, the tumor growth rate was significantly inhibited, and the animal survival is prolonged. We also analysis the gene expression changes, reveal some potential pathway that may involve in the process. Furthermore, we found focused ultrasound combined with non-oxygen-containing microbubbles also represented similar results, demonstrate the focused ultrasound induced cerebral vascular permeability increment may also contribute to the radiation therapy effect for brain tumor treatment.
EXTH-77. ONC201 EXHIBITS PASSIVE DIFFUSION AND BROAD DISTRIBUTION IN THE CENTRAL NERVOUS SYSTEM
Authors: Morrow Sara , Prabhu Varun , Tarapore Rohinton S , Theerman Gina , Lake Leah , Guo Ailan , Stogniew Martin , Allen Joshua
Published: December 2020

Imipridone ONC201 is an investigational agent in phase II clinical trials for H3 K27M-mutant diffuse midline glioma with evidence of durable objective responses and clinical symptom improvements as a single agent. The systemic pharmacokinetics of ONC201 and its ability to achieve target concentrations in supratentorial glioblastoma have been demonstrated in clinical trials; however, its clearance and distribution in midline structures and other areas of the central nervous system (CNS) haven’t been evaluated. A quantitative whole-body autoradiography study was conducted in Long-Evans rats with a single dose of [14C]-ONC201. [14C]-ONC201-related material was rapidly distributed throughout the body, with concentrations peaking at 1h for most tissues. The endocrine, metabolic/excretory, ocular and gastrointestinal tract tissues contained the highest distribution of [14C]-ONC201-derived radioactivity. Importantly, [14C]-ONC201 material was distributed evenly across brain substructures, including the meninges and midline structures of the brain; all tissues had a half-life of 1.4–7.9h, with the exception of the meninges (2397.3h). Given the uniform distribution throughout the CNS, we evaluated the permeability and efflux potential of ONC201 in bidirectional transport assays using human Caco-2 cell monolayers. ONC201 displayed high permeability in the apical to basolateral direction with apparent permeability values of 23–31×10–6 cm/s at 7–700μM. In the basolateral to apical direction, apparent permeability values were 11–24 × 10–6 cm/s. The efflux ratio values were 0.46–0.79 for ONC201, suggesting that ONC201 is not a substrate of efflux transporters. However, ONC201 exerted inhibitory potential on MDR1- (90.6%) and BCRP-mediated (81.6%) transport at 200mM. In summary, ONC201 exhibits passive diffusion without being effluxed, which may enable its rapid and wide distribution throughout the CNS. This distribution profile suggests that the compound may achieve therapeutic concentrations throughout the CNS with oral administration and that investigation of additional CNS tumors will not be hindered by drug delivery to specific anatomic structures.
IMMU-03. EFFECT OF COMBINING IRRADIATION AND ANTI-CD47 TREATMENT ON THE PHAGOCYTOSIS OF NORMAL BRAIN CELLS
Authors: Hamrick Forrest , Youssef Osama , Cheshier Samuel
Published: December 2020

Immunotherapy using CD47 blockade has shown promise in treating adult and pediatric malignant primary central nervous system tumors. We recently demonstrated that irradiation significantly enhanced anti-CD47-dependent phagocytosis of high-grade glioma cells in vitro. Furthermore, mice engrafted with high-grade human glioma that received anti-CD47 combined with irradiation showed a significant increase in the survival rate and a significant decrease in tumor growth than those that received a single treatment. However, the use of irradiation may result in potential toxicity to normal CNS cells that are not susceptible to macrophage phagocytosis in anti-CD47 monotherapy. We have now extended these studies to test the effect of combining anti-CD47 and irradiation on macrophage-mediated phagocytosis of central nervous system cells. We analyzed phagocytosis of normal human neural stem cells exposed to different irradiation doses in combination with anti-CD47 treatment to assess for the potential toxicity that uniquely exists with this treatment combination.
IMMU-18. INTERPLAY BETWEEN IDH1 AND ATRX MUTATIONS GOVERN INNATE IMMUNE RESPONSES IN GLIOMAS
Authors: Hariharan Seethalakshmi , Bowie Michelle , Hostettler Janell , Roso Kristen , He Yiping , Roskoski Martin A , Charbonneau Casey , Keir Stephen , Brown Michael , Irvin David , Zhang Gao , Gromeier Matthias , Huse Jason , Ashley David
Published: December 2020

Innate-based immunotherapies are becoming increasingly important for treating brain tumor patients. About 50% of WHO grade II and III gliomas carry mutations in IDH1 and ATRX genes. Mutant IDH1 results in the production of 2-hydroxyglutarate, an oncometabolite that promotes global metabolic and epigenetic alterations. ATRX is a SWI-SNF chromatin remodeling protein that is involved in cell cycle regulation and maintenance of genomic stability. Both IDH1 and ATRX mutations have been implicated in dysfunctional immune signaling in cancer cells. However, the interplay between these mutations in mediating innate immune responses has not been investigated in gliomas. We have derived human and mouse glioma cell lines carrying mutations in IDH1 (IDH1R132H) and/or ATRX, which we then used to generate both immune competent and nude mice models. Treating the ATRX knockout (KO) cell lines with dsRNA-based innate stimuli led to an early induction in phospho-IRF3, and late induction in phospho-STAT1 and ISG15, suggesting that ATRX deletion may enable a potent activation of type I interferon production and sensitize glioma cells to dsRNA-based innate stimuli. Our syngeneic murine glioma models confirm a survival advantage for mice carrying ATRX-KO tumors. These tumors also exhibit enhanced infiltration of T-cells and expression of activated macrophage markers. On the other hand, presence of IDH1R132H led to a suppression in baseline expression of key innate immune players, which could be rescued by the mutant IDH1 inhibitor, BAY-1436032. Cells harboring IDH1R132H and ATRX-KO retained sensitivity to dsRNA indicating that IDH1R132H does not dampen the ATRX KO-mediated sensitivity to dsRNA. Our models are under evaluation with a combination of BAY-1436032 and clinically relevant dsRNA-based innate therapies. Our data indicates the presence of an interplay between IDH1 and ATRX mutations that may regulate innate signaling in gliomas. Understanding the mechanisms governing this interplay may aid in designing therapies that exploit this interplay.
IMMU-21. THE COMBINATION OF DELTA-24-ACT WITH AN IMMUNE CHECKPOINT INHIBITOR RESULTS IN ANTI-GLIOMA EFFECT AND IMMUNE MEMORY
Authors: Puigdelloses Montserrat , Laspidea Virginia , Garcia-Moure Marc , De la Nava Daniel , Hambardzumyan Dolores , Chen Zhihong , Labiano Sara , Fueyo Juan , Gomez-Manzano Candelaria , de Larraya Jaime Gállego-pérez , M Alonso Marta
Published: December 2020

Oncolytic viruses have become promising therapeutic candidates to treat gliomas. Our group has developed Delta-24-ACT, an oncolytic adenovirus armed with the positive costimulatory ligand 4-1BBL which is capable to trigger the activation of T cells and thereby increase their antitumor immune response. Here we evaluate the anti-glioma effect of Delta-24-ACT alone or in combination with an immune checkpoint inhibitor. We observed that Delta-24-ACT was able to infect and kill murine glioma (GL261-5 and CT-2A) and also human glioma cell lines (U87-MG and U251-MG), while maintaining its replication in the latter. Of importance, Delta-24-ACT infection resulted in 4-1BBL expression on the membrane of glioma cells. Moreover, this ligand was functional and was able to stimulate CD8 lymphocytes in vitro, suggesting the potential of Delta-24-ACT to trigger an effective immune response. Furthermore, in vivo Delta-24-ACT showed anti-tumour effect in two murine glioma models by significantly increasing the median survival time and leading to long-term survivors. Mechanistic studies demonstrated an increase of the T cell infiltration and the activation of different immune cell populations by flow cytometry and a decrease of proliferative cells and tumour vessels by immunohistochemistry on FFPE brain samples. Importantly, the infiltrating lymphocytes also showed signs of exhaustion increasing the amount of IL-10 and the expression of PD-1. To overcome this exhaustion we combined Delta-24-ACT with an anti-PD-1 antibody. Evaluation of this combination in vivo further increased the median survival time of treated tumor-bearing mice and resulted in 50% long-term survivors. Rechallenge studies with the same cell line showed that combination treatment effectively protected these animals of developing tumors and therefore, the acquisition of immune memory. In summary, our data demonstrated that Delta-24-ACT induces a potent anti-tumour effect in vitro and in vivo as a result of the recruitment of immune cell populations modulating the immunosuppressive tumour microenvironment of glioma.
IMMU-23. CLINICAL AND IMMUNOLOGICAL CHARACTERIZATION OF IMMUNE CHECKPOINT MOLECULE LIGHT IN HUMAN GLIOMAS
Authors: Han Mingzhi , Li Xingang
Published: December 2020

BACKGROUND

Dysregulation of immune checkpoint molecules leads to immune evasion in human tumors but has become a viable target for tumor therapy. Here, we examined expression of LIGHT (TNFSF14), an immune checkpoint molecule, in human glioblastoma (GBM) to assess its potential as a molecular target for treatment.

METHODS

Molecular and clinical data from publicly available genomic databases containing WHO grade II-IV human glioma cases were analyzed. Immunohistochemistry was applied to assess LIGHT protein levels in primary tumor sections. Statistical analysis was performed using Matlab and R language.

FINDINGS

LIGHT was found to be elevated in aggressive gliomas, particularly in the mesenchymal molecular subtype and isocitrate dehydrogenase (IDH) wild-type GBM. LIGHT exhibited potential as a prognostic marker based on Cox regression and nomogram models. LIGHT displayed intra-tumor heterogeneity and was more highly expressed in peri-necrotic and microvascular regions. Gene ontology and pathway analysis revealed enrichment of LIGHT in multiple immune regulatory processes. Finally, in cell lineage analysis, LIGHT was found to be tightly associated with several infiltrating immune and stromal cell types which localized to the tumor microenvironment.

INTERPRETATION

Our data highlights the importance of LIGHT in the development of GBM and as a potential molecular target in combination with current immune checkpoint blockades for treatment of GBM.
IMMU-28. INDUCTION OF TERTIARY LYMPHOID STRUCTURE-LIKE T-CELL CLUSTERS BY DELIVERY OF A NOVEL GENE COMBINATION INTO AN IMMUNOCOMPETENT MOUSE MODEL OF GLIOBLASTOMA
Authors: Downey Kira , Hegde Bindu , Chheda Zinal , Zhang Jason , Okada Hideho
Published: December 2020

The lack of conventional lymphatic drainage to and from the brain parenchyma restricts the capacity of the peripheral immune system to recognize and respond to glioma antigens. In some peripheral solid tumor types and central nervous system autoimmunity, the spontaneous development of tertiary lymphoid structures (TLS) with varying degrees of organization have been observed in human patients and mice following chronic inflammation. In the cancer setting, presence of TLS are generally associated with improved prognosis, especially when they are characterized by intratumoral infiltration of CD8+ T-cells. We aimed to induce the development of TLS in vivo, utilizing our SB28 glioblastoma model which is sparsely infiltrated by lymphocytes. As a proof-of-concept study, we stably transduced SB28 with a combination of several TLS-stimulating factors that we’ve identified and injected these cells into the brain parenchyma of syngeneic C57BL/6J mice. A combination of the chemoattractant and lymphoid follicle-stimulating cytokines LIGHT, CCL21, IL-7, and IL-17 produced substantial infiltration of CD8+CD3+ T-cells into the tumor and nearby parenchyma. However, this combination was also associated with accelerated tumor growth. A modified gene combination including LIGHT, CCL21, and IL-7 promoted CD8+CD3+ T-cell infiltration by flow cytometry, T-cell clustering by immunofluorescence analysis, and inhibited tumor burden compared with the control as measured by bioluminescent imaging. There was also evidence of increased lymphatic vasculature around the margins of T-cell clustering as demonstrated by LYVE-1 staining. Together, these analyses highlight a role for these factors in stimulating the recruitment and clustering of T-cell to the glioblastoma microenvironment in a TLS-like phenomenon. Future studies will evaluate whether the recruitment of other lymphocytes and stromal cells to these TLS-like clusters can promote T-cell memory and persistence. Ultimately, we aim to provide these factors utilizing a gene delivery method that will prove translatable to the clinic and complementary to existing T-cell therapies.
IMMU-41. HIGH-THROUGHPUT RETRIEVAL OF THERAPEUTIC T CELL RECEPTORS FROM GLIOMA
Authors: Lindner Katharina , Tan Chin Leng , Bozza Matthias , Sanghvi Khwab , Poschke Isabel , Harbottle Richard , von Deimling Andreas , Wick Wolfgang , Sahm Felix , Platten Michael , Green Edward W , Bunse Lukas
Published: December 2020

Gliomas are tumors with low mutational burden with the majority of them being resistant to checkpoint inhibition due to few immunogenic antigens. Multicenter vaccine trials targeting personalized neoantigens in gliomas demonstrated feasibility and illustrated the challenges of retrieving neoepitope-specific T cells based on the prediction of immunogenic neoepitopes. Here we took an entirely different T cell-centric approach and established a single cell sequencing-based high-throughput T cell receptor (TCR) retrieval platform, exploiting the therapeutic potential of spontaneous intratumoral T cell clonotypes for the development of adoptive cell therapy. We conducted direct ex vivo TCR single cell sequencing from freshly sorted human glioma-infiltrating T cell samples. High fidelity PCR was established to clone TCRs from single cell libraries directly into episomal expression vectors further optimized for T cell therapy. In parallel to standard therapy, patient-derived xenografts were developed and characterized. Tumor-reactivity of retrieved TCRs was demonstrated against patient-derived cell lines. Collectively, we provide a novel sequencing-based platform for high-throughput identification and validation of endogenous glioma-targeting TCRs and demonstrate their therapeutic applicability.
IMMU-45. CUSTOMIZED LIPID NANOPARTICLES DELIVER NUCLEIC ACIDS TO IMMUNE CELLS IN BRAIN TUMORS
Authors: Grippin Adam , Wummer Brandon , Mendez-Gomez Hector , Wildes Tyler , Dyson Kyle , Dobson Jon , Mitchell Duane , Sayour Elias
Published: December 2020

BACKGROUND

Brain tumors are notoriously difficult to treat in part due to their isolation behind the blood brain barrier and their power to suppress antitumor immune responses. We have previously reported cationic liposome formulations capable of delivering immune modulatory nucleic acids to immune cells in various peripheral organs, but there is currently no reliable method to deliver nucleic acids into brain tumors without direct injection into the tumor site.

OBJECTIVE

Here, we report the development of a customized lipid nanoparticle to deliver immune modulatory nucleic acids to immune cells in brain tumors.

APPROACH

Cationic liposomes composed of varying lipid combinations were evaluated for their ability to deliver functional mRNA and siRNA to innate immune cells in vitro and in intracranial tumor models. Nucleic acids were labelled with Cy3 to monitor particle distribution in vivo.

RESULTS

Lipids composed of DOTAP and cholesterol selectively delivered mRNA and siRNA to intracranial GL261 and KR158b tumors. Interestingly, these particles selectively delivered these nucleic acids to CD45+ white blood cells with minimal delivery to CD45- tumor cells or normal brain tissue. Encapsulation of siRNA blocking programmed death ligand 1 (PDL1) significantly reduced PDL1 expression on innate immune cells in brain tumors, with the greatest effects on tumor-associated macrophages. Co-administration of systemic checkpoint blockade with intravenous administration of these lipid nanoparticles bearing PDL1 siRNA enabled systemic and intratumoral checkpoint blockade, leading to 37% long term survivorship in an otherwise fatal intracranial tumor model.

CONCLUSIONS

Our customized lipid nanoparticles enable potent intratumoral immune modulation via delivery of nucleic acids to immune cells in brain tumors.
IMMU-46. LINEAGE DEPLETED HEMATOPOIETIC STEM CELLS POTENTIATE IMMUNE CHECKPOINT RESPONSE TO ANTI-PD1 AND ANTI-CD276 IN MURINE GLIOMA
Authors: Larkin Trisha , Cruz Marjorie , Flores Catherine
Published: December 2020

INTRODUCTION

Glioblastoma multiforme (GBM) is a malignant brain tumor with rapid growth and infiltration, high treatment resistance, and dismal survival. Intratumoral heterogeneity and poor CNS penetration contribute to treatment resistance. Flores et al. demonstrated that hematopoietic stem cell transfer could reprogram gene expression within the tumor microenvironment, sensitizing glioma-bearing mice to treatment with immune checkpoint blockade. The objectives of this study are to expand on the role of HSCs in potentiating efficacy to immune checkpoint blockade with anti-PD1 and anti-CD276.

METHODS

KR158B murine glioma cells were implanted into the caudate nucleus of C57BL/6 mice. Hematopoietic stem cells were derived from naïve syngeneic mice and lineage depleted using the CliniMacs system. On Day 5, HSCs (105cells) were administered. Anti-CD276 and PD-1 monoclonal antibodies were administered every five days for a total of four dose administrations. Mice to allocated to no treatment, anti-CD276 only, or HSCs with or without PD1 and anti-CD276. Groups were followed for survival. Data was analyzed with GraphPad Prism.

RESULTS

The combination of lineage depleted HSCs + anti-CD276led to increased median survival when compared to the survival of mice treated with anti-CD276 monotherapy with the mice who received the combination surviving for a median of 62 days versus 36 days (p = 0.001, CI 0.204 to 1.655). The combination of HSCs + PD-1 therapy led to increased median survival of 60 days and long-term survivors, replicating prior findings from our group. Mice treated with HSC transfer, anti-B7-H3, and anti-PD-1 demonstrated a median survival of 76 days (p = 0.037).

CONCLUSION

We demonstrate a compounded survival effect when anti-B7-H3 and anti-PD1 were administered together with lineage depleted HSCs, suggesting an expanded avenue for overcoming treatment resistance. Future studies will be important to characterize the immune effects of combinatorial immune checkpoint administration with adjuvant HSC transfer.
IMMU-48. CD4+ T CELLS RESTRICT MEDULLOBLASTOMA GROWTH AND DISSEMINATION
Authors: Eisemann Tanja , Wechsler-Reya Robert
Published: December 2020

The immune system serves as a powerful defense not only against pathogens and parasites but also against neoplastic cells. Emerging immunotherapies that boost the activity of tumor-reactive immune cells or counteract immune suppressive mechanisms have shown promising effects in certain types of cancer. However, the success of immunotherapy for brain tumors has been limited, highlighting the need for a better understanding of the immune microenvironment in these tumors. Our previous studies have shown that T cells critically affect growth of the pediatric brain tumor medulloblastoma. In particular, depletion of CD4+ T cells results in more aggressive growth of medulloblastoma cells and allows these cells to metastasize to the spinal cord. The anti-tumoral effects of CD4+ T cells are not due to their function as helpers for CD8+ cytotoxic T cells, since CD8+ T cell depletion did not enhance tumor growth to the same extent as CD4+ T cell depletion. To test whether CD4+ T cells can recognize MHC class II molecules on tumor cells and attack these cells directly, we generated tumors from MHC class II knockout mice. Surprisingly, depletion of CD4+ cells in these animals still enhanced tumor growth and metastasis. These results suggest that CD4+ T cells regulate medulloblastoma growth and metastasis in a manner that is independent of CD8+ T cells and independent of MHC-II on tumor cells. Ongoing studies are aimed at elucidating the mechanisms by which CD4+ T cells regulate medulloblastoma growth, including the antigen-presenting cells that activate them and the effector cells responsible for killing tumor cells following their activation. These studies will advance our understanding of the immune microenvironment in medulloblastoma and allow us to design more effective therapies for controlling tumor growth and metastasis.
INNV-02. RADIOGRAPHIC CHARACTERISTICS AND STEROID USAGE IN LASER INTERSTITIAL THERMAL THERAPY VERSUS MEDICAL MANAGEMENT FOR BIOPSY-PROVEN RADIATION NECROSIS AFTER STEREOTACTIC RADIOSURGERY OF BRAIN METASTASES
Authors: Srinivasan Ethan , Sankey Eric , Grabowski Matthew , Griffin Andrew , Howell Elizabeth , Otvos Balint , Tsvankin Vadim , Atik Ahmet , Joshi Krishna , Barnett Gene , Fecci Peter , Mohammadi Alirezza
Published: December 2020

INTRODUCTION

Radiation necrosis (RN) occurs in 9–14% of patients after stereotactic radiosurgery (SRS) for brain metastases (BM). Medical management (MM) with steroids is a common first-line therapy, with variable response and numerous side effects, especially regarding immunotherapy. Laser interstitial thermal therapy (LITT) has been introduced as an efficacious, steroid-reducing alternative, however limited data exists comparing LITT to MM.

METHODS

Patients with biopsy-proven RN after SRS for BM who received LITT or MM at two academic centers were retrospectively reviewed. Treatment failure was defined as radiographic progression that necessitated a change in management. Measurements of total (TLV) and contrast-enhancing lesion volume (ceLV) were obtained from MRI by semi-automated analysis using the BrainLab iPlan Cranial 3.0 software.

RESULTS

Eighty-one patients were followed for 11.7 (4.3–27.0) months and 57 (70%) received LITT. Steroid cessation occurred at a median of 37 days post-LITT compared to 162 days after MM (p< 0.01). Treatment failure occurred in 5% of LITT patients at 4.0 (3.2–4.8) months and 13% of MM patients at 4.4 (4.1–5.3) months (p >0.05). Patients were 3.2 times more likely to be weaned off steroids when treated with LITT compared to MM (p< 0.01), when controlled for age, pre-operative ceLV, and post-operative seizure on multivariate analysis. Both groups demonstrated decreasing TLV and ceLV between baseline and last follow-up MRI. At 6–9 months, the LITT cohort demonstrated a -59% change in ceLV compared to -7% with MM (p >0.05). The LITT cohort demonstrated a significant decrease in ceLV between scans at 0–2 and 6–9 months (p< 0.01). The MM group did not demonstrate a statistically significant decrease in ceLV until 12 months.

CONCLUSION

This study suggests that LITT for RN significantly reduces the time to steroid cessation, and earlier radiographic response to treatment by LITT. Large, prospective trials are needed to validate these findings.
INNV-03. EFFICACY AND LONG-TERM OUTCOMES IN THE MANAGEMENT OF LARGE BRAIN METASTASIS (≥ 4 CM3) USING 2-STAGED STEREOTACTIC RADIOSURGERY (2-SSRS): AN INTERNATIONAL STUDY
Authors: Hori Yusuke , Yomo Shoji , Wei Wei , Avecillas-Chasin Josue , Barnett Gene , Suh John , Chao Samuel , Murphy Erin , Mohammadi Alireza , Angelov Lilyana
Published: December 2020

INTRODUCTION

Stereotactic radiosurgery (SRS) for brain metastases results in time-to-local failure (TTLF) that significantly correlates with target volume and prescription dose. For large brain metastases (LBM), defined as ≥ 4 cm3, SRS monotherapy can result in < 40% local control (LC) rates. To overcome the TTLF limitations in the management of LBM, 2-staged SRS (2-SSRS) has demonstrated 6-month LC rates of 85–90%. This international multi-institutional study represents the largest series of patients with LBM managed with 2-SSRS.

METHODS

181 patients with 218 LBM treated with 2-SSRS were retrospectively reviewed. Local failure (LF) was defined as ≥ 71.5% volumetric increase (equivalent to ≥ 20% increase in maximum diameter; RECIST criteria) from smallest volume date. Kaplan-Meier and log-rank tests were used to estimate and compare overall survival (OS) and TTLF; multivariable analysis was performed using Cox regression model.

RESULTS

Median age was 63 years (range: 29‒88), male sex was 50.3% with 34.8% of patients having non-small cell lung cancer. Median follow-up was 13.8 months (range:1.1‒49.4) and median OS was 14.6 months (95%CI: 12.6‒17.0). Median TTLF was 27.9 months (95%CI: 17.9‒NA) with a cumulative 6, 12 and 24-month LC of 91%, 81% and 71%, respectively. Using multivariable analysis, older age (≥ 65 years old; HR 1.58, 95%CI 1.06‒2.35, p=0.02) and larger total volume of concurrent small lesions (> 3 cm3; HR 2.05, 95%CI 1.25‒3.39, p=0.005) negatively impacted OS while younger age (< 65 years old; HR 2.60, 95%CI 1.26‒5.34, p=0.01) and RPA Class 3 (HR 3.10, 95%CI 1.26‒7.65, p=0.01) decreased TTLF. The number of concurrent LBM treated and total volume of the LBM were not significant factors.

CONCLUSIONS

This large multi-institutional dataset demonstrates excellent efficacy and long-term control of LBMs treated with 2-SSRS, which is independent of number or total volume of concurrent LBM.
INNV-20. ELEVATED INTRACRANIAL PRESSURE WITHOUT HYDROCEPHALUS IN PATIENTS WITH NEUROFIBROMATOSIS 2
Authors: Robell Lindsay , Harrison Rebecca , Sinicrope Kaylyn , Slopis John , McCutcheon Ian
Published: December 2020

BACKGROUND

Neurofibromatosis 2 is a tumor predisposition syndrome associated with multiple tumors of the central and peripheral nervous systems. Schwannomas and meningiomas are commonly observed. The occurrence of communicating hydrocephalus in this population has been observed clinically but not characterized in the literature.

METHODS

We present a retrospective case series of patients with NF2 and communicating hydrocephalus followed in the Neurofibromatosis clinic at MD Anderson Cancer Center.

RESULTS

We identified 11 patients in our Neurofibromatosis clinic with symptomatic elevation in intracranial pressure (ICP). All patients presented with worsening headaches, while six patients also presented with visual complaints leading to the diagnosis of elevated ICP. Dedicated venous imaging with either MRV or CTV was available for review in five patients. Occlusion or stenosis of the venous system (dural venous sinuses or internal jugular vein) was seen in nine patients. All patients had evidence of plaque-like meningiomas, and two patients had cervical schwannomas. Only one patient had radiographic evidence of obstructive hydrocephalus. All patients were treated for symptomatic elevated ICP with placement of a ventriculoperitoneal (VP) shunt. Three patients received acetazolamide prior to shunting, while one patient received acetazolamide after shunt placement. Seven (7/11) patients had documented improvement or resolution of headache after VP shunt placement. Two (2/6) patients had documented improvement or resolution of visual complaints.

CONCLUSIONS

We present 11 patients with NF2 who developed symptomatic elevation in ICP, ten patients without evidence of obstructive hydrocephalus and one with obstructive hydrocephalus. We hope to raise awareness of this clinical phenomena, previously uncharacterized in the literature. We propose a multifactorial mechanism involving plaque-like meningiomas, venous sinus stenosis, obstruction of cerebral venous outflow and cervical/jugular schwannomas in the development of symptomatic elevated ICP without evidence of obstructive hydrocephalus in patients with NF2.
INNV-27. BT-LIFE (BRAIN TUMOURS, LIFESTYLE INTERVENTIONS, AND FATIGUE EVALUATION): LESSONS LEARNED FROM RUNNING A NOVEL MULTI-SECTORAL RESEARCH TRIAL
Authors: G Rooney Alasdair , Hewins William , Walker Amie , Withington Lisa , Mackinnon Mairi , Robson Sara , Green Aimee , Anderson Garry , Bulbeck Helen , Torrens Claire , Emerson Julie , Dunlop Jo , Welsh Michelle , McEleney Tracy , Hopcroft Lisa , Wells Mary , McBain Catherine , Chalmers Anthony , Grant Robin
Published: December 2020

BACKGROUND

BT-LIFE is a multi-centre RCT of novel lifestyle coaching treatments for fatigued brain tumour patients. To our knowledge it is also the first example of ‘multi-sectoral research’ to combine healthcare, private, and charity sectors in this population. To maximise learning, the trial team devised a structured reflection opportunity to ask, “What went well and what would we do differently next time?”

METHOD

After trial closedown we convened a six-hour ‘focus group’ for management, principle investigators, research assistants, interventionists, qualitative researchers, trial statisticians, and the funder. Discussion was structured using a ‘timeline’ wall-chart which attendees freely populated with post-it notes summarising learning points from the trial. Minutes were taken in duplicate.

RESULTS

In total n=19 team members contributed. Many points were study-specific and will be used internally to plan a larger trial. Among points of wider interest, examples of success included: using regular teleconferences to co-ordinate a cohesive and highly collaborative team; obtaining secure nhs.net email addresses to facilitate multi-sectoral communication; and the clear value of employing one part-time research assistant per centre instead of relying on busy clinical staff to recruit. General future learning points included: speak to the prospective sponsor and ethical committees when writing the grant application to avoid pitfalls and facilitate faster opening if funding is secured; consider preceding emails with a phone call to ‘lay the ground’ in time-sensitive situations; identify staff training requirements as early as possible and cascade aggressively; and be sensitive to the fact that inter-sectoral attitudes and practices may vary widely and need actively monitored and managed. Therefore frequent and secure communication, pro-active problem-spotting, and inter-sectoral value alignment appear critical for success.

CONCLUSION

BT-LIFE provides many useful lessons for anyone interested in running multi-sectoral research.
NCMP-02. CEREBRAL SPINAL FLUID (CSF) PREDICTORS OF DEVELOPING DISSEMINATED NECROTIZING LEUKOENCEPHALOPATHY IN LEPTOMENINGEAL CARCINOMATOSIS (LMC): A SINGLE INSTITUTIONAL REVIEW
Authors: Yu Charles , Lin Irene , Leese Erika , Gatson Na Tosha
Published: December 2020

BACKGROUND

LMC is a rare complication of systemic cancer metastasis to the leptomeninges. Although first described in 1870 treatment options remain few for this rapidly fatal condition commonly excluded from clinical trials and disease site guideline updates. Whole brain radiation therapy (WBRT) and intrathecal (IT) chemotherapy are commonly employed and there is growing evidence for systemic therapies that cross the blood brain barrier. Disseminated necrotizing leukoencephalopathy (DNL) is a self-limited rare treatment-related radiographic finding variably associated with clinical decline and often misdiagnosed as progression or infection. DNL has been reported in patients exposed to IT chemotherapy and CNS irradiation. Our lab recently published improved LMC control with extended survival after standardization of Ommaya clinic IT treatment regimens, although with increased incidence of DNL.

METHODS

We retrospectively analyzed patients with LMC treated with IT chemotherapy after WBRT between 2017 – 2020. We reviewed sequential brain imaging over the treatment course to determine if there were predictive CSF markers associated with the development of DNL.

RESULTS

Of the 41 patients evaluated, 24% (n=10) developed DNL at a median 24-weeks after start of IT chemotherapy and WBRT. Of the patients with radiographically assessed DNL, 80% (n=8) experienced elevated CSF protein and 40% (n=4) had elevated white blood cells within 8-weeks prior to radiographic determination of DNL. Cytology remained benign and glucose was not significantly changed prior to DNL development.

CONCLUSION

Given the poor outcome of LMC, there is a need for treatment standardization and better understanding of treatment-associated radiographic changes. Evaluation of CSF markers to predict impending development of DNL in this treatment population might limit radiographic misdiagnoses and patient clinical decline as well as offer a potential window of opportunity for treatment de-escalation.
NCMP-06. METASTATIC CENTRAL NERVOUS SYSTEM DISEASE SECONDARY TO BURKITT LYMPHOMA IN A PATIENT WITH PRIOR HISTORY OF MELANOMA
Authors: Momah Uju , Brewer Jennifer , Tran Anthony , Shapiro David
Published: December 2020

Sporadic Burkitt’s Lymphoma accounts for only 1–2% of Non Hodgkin’s Lymphoma, and metastasizes to the central nervous system (CNS) is uncommon, occurring in about 13–17% of adult patients. 1 Melanoma is far more likely to metastasize to the CNS, occurring in about 37% of adult patients.2 Here we present the case of a 69 year old Gambian female with a prior medical history of plantar melanoma. She initially presented to her primary care provider with back pain and adenopathy, and was referred to surgical consultation for diagnosis and concern for recurrent melanoma. Her workup revealed metastatic Burkitt’s Lymphoma with disease in the abdomen, lungs and likely CNS involvement. This report chronicles her disease course and approach to management.
NCMP-12. RAPIDLY PROGRESSIVE NEUROPATHIES AS THE SOLE PRESENTATION OF NEUROLYMPHOMATOSIS
Authors: Guillermo Prieto Eibl Pilar , Rayi Appaji , Alnahhas Iyad , Giglio Pierre , Epperla Narendranath
Published: December 2020

Neurolymphomatosis (NL) is a rare and challenging entity characterized by hematological neoplastic infiltration of the peripheral nervous system. Only 40% of the cases have malignant cells on CSF sampling. We present a 52-year-old Caucasian male with primary refractory diffuse large B-cell lymphoma (DLBCL) who relapsed within 3 months of achieving complete remission to R-CHOP. First, he experienced right tongue numbness and lumbar pain. Initial MRI of the face, brain and entire spine, and CSF analysis were unremarkable. Three weeks later, he noticed left facial numbness, dysphonia, and left leg weakness. Neuraxis MRI revealed enhancement of left CN V3 and several cervical, thoracic, and lumbar nerve roots. PET/CT showed increased uptake at L4 nerve root. EMG/NGS showed left L5 denervation. After one week, he further developed new right CN VI palsy, left-sided ptosis, anisocoria, and right arm weakness. Repeat MRI showed worsening enhancement and thickening of multiple cranial nerves, cervical and lumbosacral plexus. Extensive testing for infectious, inflammatory, and paraneoplastic processes was negative. Patient underwent plasmapheresis with no response. Biopsy of nerve root was deferred due to potential permanent deficits that would impair his quality of life. Repeat CSF testing was negative for malignancy and PET/CT showed SUV of 23.8 at L4-5 with multiple new hypermetabolic foci in muscle and ribs. He received R-HD-methotrexate with clinical and radiographic (PET/CT) improvement following 2 cycles. He completed 4 cycles of R-HD methotrexate-based chemotherapy followed by autologous hematopoietic stem cell transplantation. Most of his symptoms resolved and he remained stable for about a year when PET/CT showed disease progression. He subsequently received CAR-T cell therapy with adequate tolerance and remains clinically stable. Even with negative initial imaging and CSF studies, a careful exam and attention to uncommon presentations along with serial advanced imaging (MRI, PET/CT) surveillance are key to early detection and timely treatment.