bluuebunny/crossref_metadata_2025 huggingface dataset:
EXTH-03. COMBINED TOP1 AND PARP INHIBITION ENFORCES GENOMIC INSTABILITY AND CELL DEATH IN PTEN-DEFICIENT GLIOBLASTOMA
Authors: Kim Olga , Butler Madison , Pang Ying , Yu Guangyang , Merchant Mythili , Ranjan Alice , Gilbert Mark , Pommier Yves , Wu Jing
Published: November 2021

BACKGROUND

Glioblastoma is an aggressive brain tumor with high mortality. The development of new therapies is critical for improving patient outcomes. LMP400, a novel topoisomerase I (TOP1) inhibitor, traps TOP1 cleavage complexes, thereby generating DNA damage. Poly(ADP-ribose) polymerase (PARP) is involved in DNA repair responses triggered by TOP1 inhibition. Niraparib is a potent PARP inhibitor that can cross the blood-brain barrier. Loss of phosphatase and tensin homolog (PTEN) occurs in 40% of GBM patients and is known to promote DNA damage repair deficiency. Here, we hypothesize that PTEN loss presents a vulnerability to a combined induction of DNA damage and inhibition of repair mechanisms.

METHODS

Human glioblastoma cells (U251, SNB-75, SF-295, LN18) and patient-derived glioblastoma stem cells (GSC923 and GSC827) were treated with LMP400 and/or Niraparib. Cell viability and apoptosis were examined using Celigo image cytometer and Annexin V/PI assay at 72h after treatment. Single clones after PTEN knockdown using shRNA were isolated after puromycin selection. For planned studies of PTEN knockout, sgRNA plasmids targeting PTEN will be transiently transfected and GFP-positive single KO clones will be isolated. PTEN will be restored in PTEN-null cells using lentiviral transduction.

RESULTS

CRISPR-Cas9 KO screening in GSC923 cells suggests that LMP400 is unlikely a substrate for ABC transporters. LMP400 and Niraparib synergistically induced cytotoxic effects in U251, SF-295, GSC923, GSC827 cells lacking PTEN expression. Combined LMP400/Niraparib led to increased expression of gamma-H2AX, cleaved caspase 3 and PARP, indicative of enhanced DNA damage and cell death.

CONCLUSION

LMP400 and Niraparib act synergistically to target PTEN-deficient glioblastoma by inducing DNA damage and cell death. These results will be further verified in isogenic cells in vitro as well as in vivo in a mouse model driven by PTEN deletion which would strongly support a novel therapeutic strategy in a subset of glioblastoma with PTEN loss.
EXTH-09. TUMOR PHARMACOKINETICS, PHARMACODYNAMICS AND RADIATION SENSITIZATION IN PATIENT-DERIVED XENOGRAFT MODELS OF GLIOBLASTOMA TREATED WITH THE AURORA KINASE A INHIBITOR LY3295668
Authors: Mehta Shwetal , Tovmasyan Artak , Tien An-Chi , Holter Michael , Hopkins Barbara , Margaryan Tigran , Chang Yu-Wei , Himes Sarah , Elliott Mackenna , Melendez Ernesto Luna , Pennington-Krygier Chelsea , White Connor , Molloy Jennifer , Liu Miao , Knight William , Sanai Nader
Published: November 2021

Cell-cycle deregulation is at the crux of all malignancies, including glioblastoma (GBM). Aurora Kinase A (AURKA) plays a central role in G2/M transition and faithful chromosome segregation. In this study, we evaluated the pharmacokinetics, pharmacodynamics, and radiation sensitization properties of LY3295668, a highly specific AURKA inhibitor, in orthotopic patient-derived xenograft (PDX) models of GBM. Mice with intracranial tumors were randomized to 50 mg/kg LY3295668 PO BID x 4 days vs. placebo. LY3295668 levels in plasma and contrast-enhancing tumor tissue were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Unbound fractions were determined by equilibrium dialysis. Immunohistochemistry was performed to assess levels of pAURKA (T288), phospho-Histone H3 (pHH3), and cleaved caspase 3 (CC3). For survival studies, mice with intracranial tumors were randomized to four cohorts – vehicle, radiotherapy, LY3295668 monotherapy, and LY3295668 plus radiotherapy. The median unbound concentration of LY3295668 was 270.88 nmol/L and 22.33 nmol/kg in plasma and tumor tissue, respectively – significantly higher than the biochemical IC50 of LY3295668 for AURKA inhibition (0.8 nM). A decrease in pHH3(+) cells (0.8% vs. 6.4%, p=0.036) indicated drug-induced mitotic arrest and was accompanied by an increase in CC3(+) cells (6.4% vs. 8.0%, p=0.67). Combination of LY3295668 with radiotherapy prolonged survival compared to either therapy alone in orthotopic GBM PDX models. LY3295668 is well tolerated, achieves pharmacologically-relevant unbound concentrations in GBM PDX models, and is associated with significant target modulation. Preclinical combination of LY3295668 with radiation therapy leads to synergistic effects and supports future clinical study of this multimodal strategy in glioblastoma patients.
EXTH-17. A FOCUSED ULTRASOUND BLOOD BRAIN BARRIER DISRUPTION MODEL TO TEST THE INFLUENCE OF TIGHT JUNCTION GENES TO TREAT BRAIN TUMORS
Authors: Iyer Jayashree , Akkad Adam , Tang Nanyun , Berens Michael , Zenhausern Frederic , Gu Jian
Published: November 2021

Treating primary or metastatic tumors in the brain (glioblastomas, melanoma, lung cancer, breast cancer) proves challenging by virtue of the protective function of the blood brain barrier (BBB). The tight junction proteins (TJPs) binding the specialized endothelial cells of the BBB largely contribute to the limited permeability of cancer-therapeutic drugs. In both preclinical and clinical models, low intensity focused ultrasound (LIFU) coupled with microbubbles has been proven to safely and transiently open the BBB. Despite this method being established, potential genetic influences on the durability and vulnerability of tight junctions to LIFU have not been elucidated, nor have the determinants of tight junction repair post LIFU been thoroughly investigated. We report the development of an ultrasound transparent organ-on-chip model populated by iPSC-derived endothelial cells (iPSC-EC) co-cultured with astrocytes. We aim to probe the contributions of various tight junction genes to barrier integrity along with the subsequent protein topology involved in reassembly post ultrasound. Thus, this model serves to determine parameters for ultrasound disruption for precision opening of the BBB. The BBB-On-Chip was successfully fabricated and assembled with an optimized technique that has an 80% yield of leak-free devices, with stable cavitation post nanobubble injection. Furthermore, Western blots show expression of claudin-5, a key TJP, in our iPSC-ECs. We have also demonstrated by confocal microscopy that another component of the TJP complex, ZO-1, can be visualized at iPSC-derived cell junctions. Further benchmarking of device-ultrasound interactions, successful iPSC differentiation, tight junction formation, and fabrication of nanobubbles and their assistance in ultrasound BBB disruption will be presented. Efforts are underway to characterize the contributions of tight junction genes and their variations to the integrity and disruption of the BBB.
EXTH-29. DUAL TGFB AND PD1 BLOCKADE PROMOTES GERMINAL-CENTER B-CELL IMMUNE RESPONSES AGAINST GLIOBLASTOMA
Authors: Dapash Mark , Hou David , Castro Brandyn , Rashidi Aida , Zhang Peng , Stupp Roger , Miska Jason , Lesniak Maciej , Chang Catalina
Published: November 2021

In contrast to other malignancies such as melanoma and sarcoma, Glioblastoma (GBM) remains difficult to treat with immunotherapies. Recent studies have shown that positive immunotherapeutic responses are mediated by the accumulation of germinal-center-like B cells which are predictive of survival in patients treated with neoadjuvant PD1 blockade. In contrast, GBM-associated B-cells are scarce and the establishment of germinal-center like cells have not been observed. This study seeks to identify how B-cells are driven towards their immunosuppressive phenotypes in GBM and how this prevents immunotherapeutic efficacy. Utilizing single-cell RNA sequencing (scRNA-seq) in a CT2A murine glioma model, TGFb receptors 1 and 3 were identified as the most highly expressed inhibitory receptors on GBM-associated B cells. Furthermore, using scRNA-seq, TGFb1 was identified as the most highly expressed immunosuppressive cytokine in the TME, which was produced principally by tumor-associated myeloid cells (TAMCs). Inhibiting the myeloid compartment using intracranial anti-Gr1 antibody in combination with PD1 blockade resulted in B-cells exhibiting greater proliferation and differentiation into memory B-cells in addition to germinal-center-like B-cells. Further demonstrating B-cell functional reprogramming, autologous T cells isolated from spleens exhibited greater proliferation and robust anti-tumor cytotoxicity when cocultured with tumor-associated B-cells from the dual treatment group. Finally, inhibiting a5b8 integrin, a key complex in releasing active TGFb, increased tumor-infiltrating proliferating B-cells and conferred a long-term survival benefit in the CT2A murine model. Our results demonstrate that the immunosuppressive TME of GBM is influenced by the vital interplay between B-cells and the TME through TGFb signaling. This study highlights the potential therapeutic benefits of targeting the TGFb signaling pathway in conjunction with the current standard of care for GBM.
EXTH-39. DUAL CHLOROTOXIN CAR AND MGMT ΓΔ T CELLS FOR DRUG RESISTANT IMMUNOTHERAPY OF GLIOBLASTOMA MULTIFORME
Authors: Ding Lei , Lamb Lawrence
Published: November 2021

While recent advances in immunotherapies have shown promise in extracranial tumors, Glioblastoma Multiforme (GBM) has remained challenging. We have previously developed a novel approach to the treatment of primary GBM by combining simultaneous intracranial administration of gene-modified γδ T cells expressing O-6-Methylguanine-DNA Methyltransferase (MGMT) and standard temozolomide (TMZ) chemotherapy. To further improve tumor targeting and the efficacy of the γδ T cell against GBM, we modified γδ T cells with a CAR using chlorotoxin (CLTX), a small peptide derived from scorpion venom that specifically binds the glioma-specific chloride channel, as binding domains (CLTX-CARs). MGMTp140k was co-expressed within the same CLTX-CAR vectors to confer TMZ resistance to the CAR-T cells. We optimized the CAR constructs as CLTX-CD8a-CD28TM-CD28co-CD3z-P2A-MGMT and the activation of CD69 was verified in CLTX-CAR transduced Jurkat T cells with GBM cell co-culture. We further tested dual-CLTX-CAR constructs with 2x CLTX peptide as binding domains (dCLTX-CAR) and demonstrated dCLTX-CAR-Jurkat T cells can activate T cells efficiently with improved persistence compared to the mono-CLTX-CAR-Jurkat T cells 3 weeks after transduction (84% vs 37%). In order to preserve the powerful innate-recognition properties of γδ T cells, we developed CLTX-CARs without CD3z activation domain (NoZ-CLTX-CAR) to mitigate activation induced cell death (AICD) and tonic signaling issues. NoZ-CLTX-CAR-Jurkat T cells showed no CD69 activation with GBM cells co-culture and superior CAR-T persistence compared to CLTX-CARs with a CD3z signaling domain. Furthermore, we were able to efficiently transduce (up to 70% transduction efficiency) γδ T cells with NoZ-dCLTX-CAR lentiviral which demonstrated enhanced cytotoxicity against GBM cells compare to non-transduced control γδ T cells. Our approach of combining the dCLTX-CAR and TMZ resistance will be further validated in animal model experiments and could be a potential candidate for clinical development for GBM.
EXTH-41. IMPROVING THE RADIOSENSITIVITY OF DIFFUSE INTRINSIC PONTINE GLIOMAS (DIPG) BY TARGETING HYPOXIA AND MITOCHONDRIAL METABOLISM
Authors: Shen Han , Chang Cecilia , Ing Prunella , Cook Kristina , McKelvey Kelly , Lai Joey , Gloss Brian , Prior Victoria , O'Neill Geraldine , Blackburn Anneke , Gee Harriet , Hau Eric
Published: November 2021

DIPG is the leading cause of brain tumor-related death in children. Radiotherapy is the only treatment that offers transient benefit and provides palliative care. DIPGs are hypo-perfused with tumor cells being exposed to hypoxia, a potent barrier to effective radiotherapy. Reducing the oxygen consumption rate (OCR) is therefore a potential strategy to reduce tumor hypoxia. We therefore performed a high-throughput screening with 1963 FDA-approved drugs that could reduce tumor hypoxia and OCR, thereby improving radiosensitivity of DIPGs. A subset of anti-diabetic drugs was identified, with phenformin amongst the most potent. It significantly reduced OCR in a panel of DIPG cultures and subsequently suppressed hypoxia in 3-dimensional DIPG neurosphere models that mimic the hypoxic microenvironment. In addition, phenformin demonstrated greater anti-tumor activity and radiosensitizing effect with much lower doses compared with metformin, a less potent biguanide that improved radiosensitivity of DIPG in a patient-derived xenograft (PDX) model in our previous study. The effect of phenformin was further enhanced by combining a second drug dichloroacetate that simultaneously attenuated phenformin-induced acidification rate. Specifically, the combination of phenformin and dichloroacetate induced higher levels of hypoxia inhibition, reactive oxygen species, DNA damage and apoptosis. RNA sequencing demonstrated significant changes induced by the combination treatment in cell-cycle, DNA repair, unfolded protein response and alternative energetic pathways. These changes were further validated by PCR array and western blotting at mRNA and protein levels. In addition, two master regulators that enhance the metabolic capacity of tumor cells through increased glycolysis thus contributing to radioresistance, HIF-1α and c-Myc, were also significantly suppressed by combination treatment. Ultimately, the triple combination of phenformin, DCA and irradiation demonstrated the most potent efficacy in inducing DNA damage, apoptosis and clonogenic inhibition in DIPG cultures. This promising triple combination therapy is currently being tested in our PDX cohort in vivo.
EXTH-49. FOCUSED ULTRASOUND AND 5-ALA MEDIATED ELIMINATION OF DIFFUSE MIDLINE GLIOMA
Authors: Schaab Luana , Ferry Yann , Ozdas Mehmet , Kritzer Bettina , Mourabit Sulayman , Marcus Stuart , Nazarian Javad
Published: November 2021

Diffuse midline glioma (DMG) is a devastating and incurable childhood brain cancer. With a median survival of only 9 to 11 months, over 90% of children affected by DMG die within two years of diagnosis. Despite decades of research and a growing understanding of the biology of these tumors, there have been no advancements in therapies for DMGs. Tumor heterogeneity and diffuse infiltration in inoperable brain regions make these tumors uniquely difficult to manage both surgically and pharmacologically. Therefore, there is an urgent need for the exploration of novel treatment regimens. Focused Ultrasound (FUS) is an emerging technology with significant clinical potentials. Sonodynamic therapy (SDT) is an up-and-coming treatment strategy aiming to non-invasively eliminate tumor cells by acting through compounds known as sonosensitizers, which render tumor cells sensitive to ultrasound energy. Recently, 5-Aminolevulinic acid (5-ALA), an FDA-approved molecule, has been proposed as a sono-sensitizing agent. 5-ALA mediated SDT prolonged survival in C6 rat glioma models by selective elimination of tumor cells upon sonication. Mechanistically, it is thought that 5-ALA uptake and metabolic conversion into Protoporphyrin IX (PpIX) occurs preferentially in tumor cells due to differential activity of enzymes involved in heme metabolism. Here, we investigated SDT in DMG cells treated with 5-ALA. PpIX fluorescence increased linearly up to 24 h upon 5-ALA treatment and accumulated significantly more (1.6-fold, p < 0.01) when compared to C6 cells. Consequently, FUS sonication of 5-ALA treated DMG cells at 250 kHz significantly (p < 0.05) decreased DMG cell viability compared to treatment with 5-ALA or FUS alone. Here, we show the first 5-ALA mediated sonodynamic effect in DMG cells, leading to enhanced cell death. Our findings provide a rationale for considering clinical investigation of 5-ALA mediated sonodynamic therapy in DMG.
EXTH-52. SYSTEMIC AND BRAIN PHARMACOKINETICS OF THE AMP-ACTIVATED PROTEIN KINASE SELECTIVE INHIBITOR SBI-0206965 AS A POTENTIAL THERAPEUTIC AGENT FOR THE TREATMENT OF GLIOBLASTOMA MULTIFORME
Authors: Desai Janki , Gawali Mruniya , Karve Aniruddha , Gudelsky Gary , Sallans Larry , Dasgupta Biplab , Seibel William , Desai Pankaj
Published: November 2021

PURPOSE

AMP-activated protein kinase (AMPK) is a molecular hub for cellular metabolic control. Recent evidence suggests that AMPK is a “druggable” novel target for the treatment of Glioblastoma Multiforme (GBM). However, AMPK-inhibitory compounds are largely limited to compound C, which has a poor selectivity profile. SBI-0206965 is a diaminopyrimidine derivative that directly inhibits AMPK with 40-fold greater potency and markedly lower kinase promiscuity than compound C. The current studies provide insights into systemic pharmacokinetics and plasma to brain partitioning of SBI-0206965.

METHODS

We conducted an intracerebral microdialysis study employing jugular vein-cannulated Sprague Dawley rats (males, 6- 8 weeks). Serial brain extracellular fluid (ECF) and venous blood samples were collected up to 10 hrs following intraperitoneal administration of SBI-0206965 (25 mg/kg). These samples were then quantitated for SBI-0206965 levels using a LC/MS method (Thermo Scientific LTQ-FT™, Ionization: Electrospray Ionization; positive ion). PK analysis was performed using the Non–Compartmental Analysis (Phoenix® WinNonlin 8.2 Certara USA, Inc.).

RESULTS

Plasma and ECF peak concentrations (Cmax) were 7.15 µM and 0.68 µM, whereas the time to peak (Tmax) were 0.5 and 1 hr, respectively. The plasma and brain ECF elimination half-lives were 1.5 and 3 hours, respectively. Plasma protein binding of SBI-0206965 was 82%. A comparison of the brain ECF Cmax and area under the curve (AUC) to corresponding plasma values suggested that the brain partitioning of the compound was 10-18%. When corrected for unbound fraction in plasma the AUC ratio was 0.86. Thus, these studies show that SBI-0206965 has adequate brain penetration. Further studies are now in progress to assess selectivity of SBI-0206965 for AMPK expressing cell lines, efficacy against patient-derived GBM and PK in tumor-bearing mice.

CONCLUSION

Results from this study will help to design optimal dosing regimen of SBI-0206965 in our efforts to explore AMPK as a GBM-specific drug target.
EXTH-53. ANTI-ROBO1 CAR T CELLS EFFECTIVELY TARGET MALIGNANT BRAIN CANCER
Authors: Chokshi Chirayu R , Brakel Benjamin , Rossotti Martin A , Venugopal Chitra , Salim Sabra , Bloemberg Darin , Vora Parvez , Henry Kevin A , Singh Sheila K
Published: November 2021

No standardized treatment exists for patients with recurrent glioblastoma (GBM). Given the aggressive nature of the disease and difficulty in modeling tumor recurrence, minimal efforts have been made to design rational therapies against it. The roundabout guidance receptor 1 (ROBO1) protein is involved in axonal guidance during neurodevelopment and is aberrantly upregulated in glioma where it mediates glioma cell migration. Here, we present that ROBO1 is highly expressed on the surface of malignant and treatment-refractory brain tumor initiating cells (BTICs), prompting the development of an anti-ROBO1 CAR-T cell therapy. Using the binding region of a single-domain antibody targeting ROBO1, we developed second-generation anti-ROBO1 CAR-T cells specific and effective against ROBO1-expressing BTICs. Upon antigen exposure, anti-ROBO1 CAR-T cells upregulated markers of activation and degranulation. Additionally, treatment of orthotopic and patient-derived brain tumor xenograft models with anti-ROBO1 CAR-T cells resulted in reduced tumor burden and prolonged survival, demonstrating the therapy’s therapeutic potential for treating neoplastic brain malignancies.
EXTH-54. PHOTODYNAMIC ONCOLYTIC VIROTHERAPY INCORPORATING GENETICALLY ENGINEERED PHOTOSENSITIZER KILLERRED FOR THE TREATMENT OF CENTRAL NERVOUS SYSTEM MALIGNANCIES
Authors: Shimizu Kazuhide , Kahramanian Andranik , Wakimoto Hiroaki
Published: November 2021

BACKGROUND

Photodynamic therapy (PDT) is a targeted cancer therapy utilizing tumor-specific accumulation of photosensitizers and generation of reactive oxygen species (ROS) upon receiving specific light. The deadly CNS malignancies, high-grade gliomas and malignant meningioma, represent excellent candidates for this therapeutic method due to accessibility to light irradiation at the time of surgery. On the other hand, oncolytic virotherapy using a genetically engineered oncolytic herpes simplex virus (oHSV), has been intensively investigated as a multi-mechanistic therapy against these tumors. One of the advantages of oHSV is its ability to incorporate therapeutic transgenes. Our study aims to address our hypothesis that incorporating KillerRed, the first fully genetically encoded photosensitizing fluorescent protein, into oHSV will establish photodynamic oncolytic virotherapy that enhances tumoricidal efficacy as a novel treatment approach to CNS neoplasms.

METHOD

The optical properties of the intracellular KillerRed protein expressed in cells were determined by scanning by a multi-mode microplate reader to determine the optimal irradiation wavelength. In vitro efficacy of KillerRed-mediated PDT was tested using human glioblastoma and malignant meningioma cell lines. oHSV G47delta expressing KillerRed was constructed by a bacterial artificial chromosome-based method. KillerRed-transduced cells were confirmed to express red fluorescence, followed by irradiation by an amber color LED. Cell death and viability were assessed by DAPI staining and MTS assay, respectively. ROS generation post light treatment was assessed by DCF-DA cellular ROS assay.

RESULTS

KillerRed had an excitation peak at 580-585nm in transduced cells. Light irradiation by an amber LED after infection with G47delta-KillerRed induced increased cell growth inhibition and death compared with virus infection without light or light alone. Increased ROS production was observed following KillerRed PDT.

CONCLUSION

G47delta-KillerRed enables a combination of oncolytic virus therapy and PDT to augment tumor killing. This approach is being tested in in vivo mouse models using potent focused laser irradiation.
EXTH-60. PRECLINICAL STUDY OF PAMIPARIB, A CNS-PENETRANT PARP INHIBITOR, IN IDH1/2 MUTATED GLIOMAS
Authors: Hong Christopher , Sundaram Ranjini , Bindra Ranjit
Published: November 2021

Our group has demonstrated that IDH1/2 mutated gliomas harbor intrinsic homologous recombination (HR) defects mediated by the oncometabolite, 2-HG, rendering them sensitive to PARP inhibitors. Here, we studied the efficacy of pamiparib, a CNS-penetrant PARP inhibitor with potent PARP trapping ability, in combination with temozolomide (TMZ) and radiation therapy (RT) in IDH1/2 mutated gliomas. We also studied the pharmacokinetics of BGB290 to demonstrate CNS penetrance. We performed a series of DNA repair functional studies with in vitro short- and long-term viability assays, as well as in vivo studies utilizing an orthotopically injected rat glioma model with bioluminescence. Pharmacokinetics was measured with a previously validated LCMS/MS technique. Short-term and long-term viability assays in paired isogenic IDH1 wildtype and mutant cell lines showed the IDH1 mutation conferred enhanced sensitivity to pamiparib with several-fold decreases in IC50, as well as TMZ and RT as expected. Combination treatment with pamiparib and TMZ or RT also demonstrated synergistic interactions in these same cell lines, dependent upon IDH1 mutation status. An ELISA assay confirmed PARylation inhibition by pamiparib at the nanomolar range in a dose-dependent manner. Pharmacokinetic analysis demonstrated favorable CNS penetration with tumor:plasma ratios ( >0.20) observed with low (3 mg/kg) and high (6 mg/kg) doses of pamiparib, orally administered BID to rats harboring intrinsic rat glioma intracranial tumors. These levels persisted between 2 and 8 hours after last dosing. Pamiparib also selectively penetrated tumors over normal brain with normal brain:plasma ratios under 0.20. These data suggest pamiparib may selectively target IDH1/2 mutated gliomas and act synergistically with TMZ and RT to exploit intrinsic HR defects associated with these tumors. Pharmacokinetic analysis suggest favorable CNS penetration after standard bid oral administration. As such, these results lay the groundwork for study of pamiparib with TMZ and/or RT in patients with IDH1/2 mutated gliomas.
EXTH-71. FUNCTIONAL GENOMICS IDENTIFIES EPIGENETIC REGULATORS AS NOVEL THERAPEUTIC TARGETS FOR SONIC HEDGEHOG MEDULLOBLASTOMA
Authors: Tsiami Foteini , Piccioni Federica , Root David , Bandopadhayay Pratiti , Segal Rosalind , Tabatabai Ghazaleh , Merk Daniel
Published: November 2021

Medulloblastoma (MB) is among the most common malignant pediatric brain tumors. Among its four molecularly heterogeneous clinical variants, sonic hedgehog (SHH) subgroup comprises 30% of all MBs and is characterized by constitutive activation of the canonical SHH signaling pathway. Although Smoothened (Smo) inhibition has emerged as a promising therapeutic target for this tumor entity, primary or acquired resistance impedes its clinical efficacy. Thus, further insight into the molecular mechanisms underlying acquired resistance to Smo inhibition are urgently needed to overcome this challenge. Here, we performed a genome-wide CRISPR/Cas9 knockout screen in a murine and a human SHH-MB cell line, SMB21 and DAOY, respectively, in order to unravel tumor-specific genetic vulnerabilities. Our data provide functional evidence that SMB21 cells highly depend on key members of the SHH pathway such as Smo and Gli1 for their survival. In contrast, none of those positive regulators of SHH signaling scored in DAOY cells, suggesting that they are not a faithful human model of this tumor subtype. Of note, functional genomics identified SMB21-context specific essentialities beyond the SHH pathway that include epigenetic regulators such as Dnmt1, Smarca5 and Smarca4. Further in vitro pharmacological validations demonstrate that Dnmt1 inhibition is efficacious in clinically relevant concentrations in SHH-associated cell lines, both sensitive and resistant to Smo inhibition, suggesting novel therapeutic avenues for SHH-MB. By employing genome-scale knockout screens in murine cell lines faithfully recapitulating the biology of human SHH-MB, we aim to decipher synthetic lethal interactors for Dnmt1 inhibitors that could potentially serve as a combinatorial treatment approach for SHH-MB. Finally, genetic ablation and pharmacological inhibition of epigenetic regulators will be evaluated in in vivo mouse models of SHH-MB. Summarizing, our data highlight the potential of inhibitors of epigenetic regulators in SHH-MB sensitive, as well as resistant to Smo inhibition.
EXTH-76. DEVELOPING THE NOVEL COMBINATION THERAPY OPTIONS FOR CANCER THERAPY USING TUMOR TREATING FIELDS TOGETHER WITH THE CHEMO AGENTS TARGETING THE REPLICATION STRESS PATHWAY
Authors: Karanam Narasimha Kumar , Story Michael
Published: November 2021

Tumor Treating Fields (TTFields) as a component of cancer therapy has been shown to provide significant clinical benefit. The disruption of mitosis was identified as the first mechanism of action, however, a novel role for TTFields outside of mitosis where TTFields downregulates the Fanconi’s Anemia genes and proteins results in replication stress and reduced DNA repair capacity. Given these results we hypothesized that TTFields would increase the sensitivity of tumor cells to chemotherapy agents that increase replication stress. An analysis of agents that target replication stress in different ways was initiated. PARP1: Targeting PARP1 protects DNA breaks by recruiting DNA repair and checkpoint proteins to the sites of damage. Using the PARP1 inhibitor olaparib followed by radiation resulted in synergistic cell killing compared to radiation or olaparib alone or in combination. Etoposide: Etoposide forms a ternary complex with topoisomerase II and prevents re-ligation of DNA strands to elicit DNA strand breaks and replication stress. When combined with TTFields cell killing increased synergistically vs. etoposide alone. AZD6738: ATR is an essential kinase regulator of the replication checkpoint that plays a critical role in safeguarding genome integrity from replication stress. The advantage of combining TTFields with the ATR inhibitor-AZD6738 was tested for cell killing and the combination vs. AZD6738 was found to be synergistic. Irinotecan: Irinotecan traps topoisomerase I- DNA in a ternary cleavage complex and inhibits the initial cleavage reaction and re-ligation steps resulting in increased replication stress. Irinotecan and TTFields was tested and found to be highly effective at tumor cell killing. Collectively, our results suggest that it is likely of considerable clinical benefit to combine TTFields with chemotherapy agents that cause replication stress. This notion may explain the results of a number of clinical trials and suggests that there may be novel TTFields/replication stress-inducing chemotherapy agent combinations worth exploring.
QOLP-09. AUTONOMY DURATION AS ANALYZED BY KPS ≥ 70 CUMULATIVE TIME IN PATIENTS WITH BIOPSY-ONLY GLIOBLASTOMA (BO-GBM). A SUB-ANALYSIS OF THE TIMONE COHORT
Authors: Harlay Vincent , Loundou Anderson , Boucard Céline , Petrirena Gregorio , Barrie Maryline , Campello Chantal , Autran Didier , Padovani Laeticia , Figarella Dominique , Boissonneau Sébastien , Dufour Henry , Baumstark Karine , Tabouret Emeline , Chinot Olivier
Published: November 2021

BACKGROUND

Maintenance of autonomy is a crucial and understudied issue for glioblastoma patients whose outcome is poor. Biopsy-only glioblastoma (BO-GBM) present with short survival and independence is of particular importance. Our objective was to explore their functional outcome.

MATERIAL AND METHODS

A regional glioma SIRIC cohort was conducted at CHU Timone in 2014-2017 and we retrospectively reviewed the BO-GBM subgroup. We prospectively collected age, tumoral surface, treatment allocated and completed, and survival outcome. Functional independence was analyzed as a cumulative time of Karnofsky performance status (KPS) ≥ 70 from the date of diagnosis until death. We analyzed potential factors associated to time with KPS ≥ 70.

RESULTS

Among 535 patients enrolled in the cohort, surgery was restricted to biopsy in 139 patients (BO-GBM). Mean tumoral surface measured on gadolinium-enhanced T1-weighted MRI was 1198 mm2 (min: 65; max: 4515mm2). Forty-seven patients were referred to radiotherapy-temozolomide (RT-TMZ), 75 considered unfitted for RT received chemotherapy upfront (CT-UF), and 17 patients were referred to palliative care. Median OS was 7.5 months (95%CI: 6.0-9.2), 14.0 months (95%CI: 9.7-18.7) and 6.0 months (95%CI: 4.6-7.7) for BO-GBM, RT-TMZ and CT-UF respectively. At diagnosis, 81 (58.3%) patients presented with self-care capacity (KPS ≥ 70%). For these patients, median time of autonomy preservation was 7.6 months (95%CI: 6.1-9.0). Median time of autonomy preservation differed according to treatment modalities: it was 8.6 months (95%CI: 5.9-11.3) versus 6.3 months (95%CI: 2.9-9.7) for RT-TMZ versus CT-UF group respectively (p< 0.001). In multivariate analysis, time with KPS ≥ 70 was correlated with age (p=0.001) and KPS at diagnosis (p< 0.001).

CONCLUSION

Patients with inoperable GBM referred to radiotherapy-temozolomide present a valuable duration of functional independence, although shorter in patients not referred to RT. Duration of functional independence could be considered in addition to PFS and OS for treatment evaluation in patients with GBM.
QOLP-16. PATIENT-REPORTED SELECTION FOR INCIDENTAL FINDINGS IN A COMPREHENSIVE GENOMIC TRIAL: A DANISH SINGLE INSTITUTION EXPERIENCE FROM THE COPENHAGEN GLIOBLASTOMA COHORT
Authors: Nørøxe Dorte Schou , Poulsen Hans , Lassen Ulrik
Published: November 2021

INTRODUCTION

Participation in clinical trials is a high priority in the neuro oncology community and requires an informed, signed consent. However, patient information is increasingly complex as many trials include comprehensive molecular analyses and, according to Danish legislation, must include a statement about incidental findings. Incidental findings can range from variants of unknown significance to pathogenic variants in the mismatch repair-genes (MMR) and BRCA1-2. Pathogenic variants have been reported in 1-18% of cancers and can have significant influence for the patient and family. Patients with glioblastoma (GBM) can have impaired cognitive function, both due to GBM and due to morbidity after surgery. This can limit access to clinical trials as some patients might not understand the study information. We investigated whether patients were interested in participating in a comprehensive genomic trial and where they marked their preference of information for incidental findings.

PATIENTS AND METHODS

108 consents from a published study from the Copenhagen Glioblastoma Cohort were examined. The study period was 2016-2019 and included whole exome- and RNA sequencing. The consent included three alternatives to receive information about incidental findings; 1) none, 2) if incidental findings could be treated or future disease be prevented or 3) full information even though no treatment or prevention existed.

RESULTS

A total of 108/111 (97.3%) patients consented to participate. Each category was marked as follows: 33 (30.6%) marked 1), 24 (22.2%) marked 2) and 45 patients (41.7%) marked 3), respectively. Six consents were N/A as either two or no boxes were marked. No pathogenic incidental findings were identified.

CONCLUSION

We found a high interest in trial participation despite of complex study information. Information about incidental findings was spread between groups with majority of patients interested in receiving full information, suggesting that complex information does not hinder participation in molecular-based trials for GBM patients.
QOLP-19. FINANCIAL TOXICITY AND DISTRESS DURING THE COVID-19 PANDEMIC IN PEOPLE LIVING WITH PRIMARY BRAIN TUMORS
Authors: Leeper Heather , Vera Elizabeth , Acquaye Alvina , Briceno Nicole , Choi Anna , Christ Alexa , Grajkowska Ewa , Jammula Varna , Levine Jason , Lindsley Matthew , Reyes Jennifer , Roche Kayla , Rogers James , Timmer Michael , Boris Lisa , Burton Eric , Lollo Nicole , Panzer Marissa , Penas-Prado Marta , Pillai Valentina , Polskin Lily , Theeler Brett , Wu Jing , Gilbert Mark , Armstrong Terri
Published: November 2021

Primary brain tumor (PBT) patients experience high symptom burden and functional limitations, which may be impacted by the economic strain and mood disturbance during the COVID-19 pandemic. We assessed financial toxicity and associated patient reported outcomes (PROs) after one year of lockdown in a cohort of PBT patients. Patient and disease characteristics and PROs including FACIT-COST, MDASI-Brain Tumor, PROMIS-Anxiety/Depression short forms, and EQ-5D-3L were collected from 7/2020 to 5/2021 from participants in our Natural History Study. Descriptive statistics, Pearson correlations, and independent samples t-tests evaluated PRO relationships. The cohort included 112 PBT patients: 57% male, 87% white, mean age = 47 (range 25 – 80). Majority were married (65%), completed ≥ 4-year college degree (73%), earned annual family income ≥ $50,000 (68%) and living with a high-grade glioma (72%) complicated by recurrence (51%). Using FACIT-COST, 56% reported some financial hardship due to illness with a mean FACIT-COST of 28.3 (SD = 11.3, range: 0 - 44). Half of patients reported feeling moderately to extremely anxious or depressed. Non-Whites and Hispanics as well as those not currently working reported worse financial toxicity compared to White non-Hispanics and individuals currently working (21.4 vs 29.8 and 25.7 vs 30.4, respectively). Worse financial toxicity scores strongly correlated with worse overall symptom burden (r = -0.55) and interference (r = -0.42), worse anxiety (r = -0.39) and depression scores (r = -0.44), and worse overall HRQOL scores (r = –0.33)[all p< .01]. This is the first report of FACIT-COST in PBT patients to our knowledge and demonstrates that non-White individuals living with high grade glioma who are not currently working due to their tumor reported worse financial toxicity which was strongly correlated with higher symptom burden and interference with lower HRQOL. Future studies to assess financial toxicity longitudinally and post-pandemic using the FACIT-COST are needed.
QOLP-24. COMBATING EMOTIONAL DISTRESS AND SOCIAL ISOLATION IN PEDIATRIC BRAIN TUMOR FAMILIES: A CASE STUDY OF A NATIONAL NONPROFIT’S IMPLEMENTATION OF A PEER INTERVENTION TO IMPROVE QUALITY OF LIFE
Authors: Riley Kathy
Published: November 2021

Interpersonal and emotional support issues present some of the deepest and most pervasive challenges for patients and families. In the Pediatric Brain Tumor Foundation’s 2018 Community Health Needs Assessment report (n=900), family survey respondents cited patient anxiety and depression as the greatest challenge patients face in nearly one in three cases, with isolation lagging not far behind. Beyond patients, interpersonal and emotional issues represent the dominant category of challenges for families as well. Many parents stated they felt guilty thinking about their problems, as the patient’s suffering far exceeded their own, and nearly half reported often neglecting their own well-being at considerable personal cost. To combat these interpersonal and emotional support issues, the Pediatric Brain Tumor Foundation launched a national intervention in 2020 titled the Peer to Peer Mentoring Program. The program matches patients or family members with trained mentor volunteers who have experience facing the challenges that come with a pediatric brain tumor diagnosis. The theoretical framework used to design the intervention is the Social Support theory. This theory is based on the work of House (1981) who defines social support as the functional content of relationships and categorizes four broad types of supportive behaviors: emotional support, instrumental support, informational support and appraisal support (Glanz, Rimer & Viswanath, 2008). The case study explores the technology platform employed to track matches; how matches are made; how mentors are recruited and trained; how mentees are recruited; and how mental health support is provided to mentors. Analysis of peer meeting logs elucidates key themes that emerge in peer encounters as well as key program challenges and how they are being overcome. This theoretical and practical presentation will define the interpersonal and emotional support issues families face, describe the peer intervention’s goals and objectives, and report on insights gained and outcomes achieved.
QOLP-31. QUALITY OF LIFE OF PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA DURING TTFIELDS THERAPY IN ROUTINE CLINICAL CARE: FIRST RESULTS OF THE TIGER STUDY
Authors: Bähr Oliver , Tabatabai Ghazaleh , Fietkau Rainer , Goldbrunner Roland , Glas Martin
Published: November 2021

OBJECTIVE

Current interdisciplinary treatment strategies for glioblastoma (GBM) outside clinical trials include maximally safe resection, followed by radiation and chemotherapy. The results of the positive phase III trial EF-14, adding Tumor Treating Fields (TTFields) to temozolomide (TMZ) maintenance therapy, brought an additional treatment method to clinical routine. The TIGER (TTFields In GErmany in Routine Clinical Care) study documents the use of TTFields in routine clinical care with a focus on health-related quality of life (HRQoL) within 4 months after starting therapy, treatment compliance and duration.

METHODS

This multi-center, prospective, non-interventional study in Germany (NCT03258021) included ndGBM patients eligible for TTFields therapy. Following their consent, patients received a comprehensive introduction to the therapy and baseline demographic data were collected. Information on TTFields therapy decision was evaluated based on a dedicated TTFields questionnaire at baseline in both arms; follow-up information on how patients handle the therapy was collected two months after TTFields treatment start. HRQoL was assessed in patients deciding for TTFields therapy at baseline and at 2 and 4 months using the EORTC-QLQ-C30/BN-20 questionnaires.

RESULTS

Between August 2017 and November 2019, 710 patients (259 female/451 male) were enrolled at 81 participating centers. The mean age was 58.5 years (range: 19.0-85.0; Cut-off: August 31, 2020). The overall baseline characteristics of the study group reflects a typical GBM population. Of these, 582 (82%) decided to start TTFields; 128 (18%) refused TTFields treatment. HRQoL did not decline during TTFields therapy except for itchy skin, comparable to the EF-14 trial. A detailed analysis of the cohort as well as their reported QoL will be presented.

CONCLUSION

The TIGER study is the largest non-interventional trial on the use of TTFields in routine clinical care. The use of TTFields in patients with ndGBM did not impair HRQoL during the follow-up period, except for more itchy skin.
QOLP-37. MOOD DISTURBANCE IN PATIENTS WITH CENTRAL NERVOUS SYSTEM (CNS) TUMORS DURING THE COVID-19 PANDEMIC
Authors: Polskin Lily , Pillai Valentina , Vera Elizabeth , Acquaye Alvina , Briceno Nicole , Choi Anna , Christ Alexa , Grajkowska Ewa , Jammula Varna , Leeper Heather , Levine Jason , Lindsley Matthew , Reyes Jennifer , Roche Kayla , Rogers James , Timmer Michael , Boris Lisa , Burton Eric , Lollo Nicole , Panzer Marissa , Penas-Prado Marta , Theeler Brett , Wu Jing , Gilbert Mark , Armstrong Terri , King Amanda
Published: November 2021

BACKGROUND

Primary CNS tumors are associated with uncertainty likely contributing to mood disturbance that is common throughout the disease trajectory. The intersection of the COVID-19 pandemic with a CNS tumor diagnosis may further impact the anxiety/depression experienced in this population. This study assessed key anxiety/depression symptoms in patients with CNS tumors prior to and during the COVID year.

METHODS

Patient reported outcomes (PROs), including the PROMIS Anxiety and Depression Short Forms and EQ-5D-3L, were collected at the time of clinical or telehealth evaluation from the COVID year (March 2020-February 2021) and were compared to assessments through February 2020 (a NOB-normative sample), reflecting what we would typically see in our regular clinic evaluations.

RESULTS

The COVID sample (N = 178) was primarily White (82%), male (55%), median age of 45 (range 18–79), and KPS ³ 90 (50%). The majority had high grade (70%) brain (83%) tumors with ³ 1 prior recurrence (60%) and 25% were on active treatment. Visits were primarily conducted via telehealth (64%) and 20% had progression at assessment. Compared to the NOB-normative sample, patients reported significantly higher depression scores (moderate-severe, 17% vs. 12%, p < 0.05), but not anxiety (18% vs. 16%). Eleven percent reported both moderate-severe anxiety and depressive symptoms (8% pre-COVID). Overall health assessed by the EQ-5D-3L was similar to the normative sample in all dimensions, apart from impact of moderate/extreme mood disturbance, which was more prevalent in the COVID year (53% vs. 43%, p < 0.05%).

CONCLUSION

Patients with CNS tumors are at risk for significant symptoms of depression and anxiety; this risk was heightened during the COVID year. Further evaluation of clinical factors associated with risk are underway. These findings highlight the need for assessments and interventions that can be administered via telehealth to address the mental health needs of this vulnerable population.

Radiobiology
RTID-07. AN INVESTIGATOR-LEAD PHASE II CLINICAL TRIAL OF ACCELERATOR-BASED BNCT FOR REFRACTORY AND RECURRENT HIGH-GRADE MENINGIOMA
Authors: Miyatake Shin-Ichi , Kawabata Shinji , Takai Satoshi , Wanibuchi Masahiko
Published: November 2021

BACKGROUD

Boron neutron capture therapy (BNCT) is tumor-selective particle radiation. We applied this unique technique and achieved excellent clinical results for recurrent and refractory high-grade meningiomas (HGM) using reactor neutron sources (Neuro-Oncology, in press, doi:10.1093/neuonc/noab108). Recently accelerator-based neutron sources (ABNS) was approved for medical device in Japan for refractory H&N cancers.

PURPOSES

Based on these situations, we proposed “A phase II clinical trial using accelerator-based BNCT system for refractory recurrent HGM” for AMED in Japan which is similar to NIH in USA. This proposal was successfully accepted.

DESIGN

We prepared 2 study groups, BNCT test treatment group and control best supportive care group, for RCT. PFS and OS were set-up as primary and secondary endpoints, respectively. Rescue BNCT is allowed for control group patients, if they showed PD during observation. The trial started in August 2019.

METHODS

Twelve BNCT and 6 control subjects will be included. Patients’ eligibility criteria is recurrent HGM after some radiotherapy. Cyclotron-based ABNS system is used for neutron source. Neutron-irradiation time is determined not to exceed to 7.5 Gy-Eq for scalp dose which was referencing preceding phase I trial for malignant gliomas.

PROGRESS

As of March 2021, 13 subjects were included, 9 for BNCT treatment group, 4 for control best supportive care group. All 4 control subjects showed PD during 2 months while 8 out of 9 subjects showed SD or PR during observation period and there is a statistical significance in both groups, by Log-rank and Wilcoxon analyses with p=0.0012 and 0.0020, respectively.

CONCLUSION

We started this RCT and will introduce the interim report of this clinical trial in the meeting. At the SNO meeting we will present further detail of this trial.
SURG-03. FUNCTIONAL OUTCOMES OF LASER INTERSTITIAL THERMAL THERAPY (LITT) VERSUS RESECTION IN THE TREATMENT OF LESIONS IN OR NEAR THE PRIMARY MOTOR CORTEX
Authors: Srinivasan Ethan , Lerner Emily , Edwards Ryan , Huie David , Fecci Peter
Published: November 2021

INTRODUCTION

Laser interstitial thermal therapy (LITT) is a minimally-invasive treatment option for radiographically-progressive (RP) brain metastases. This study compares the functional outcomes of LITT vs resection (RS) for lesions in or near the primary motor cortex (PMC).

METHODS

Retrospective review was performed of patients treated for PMC lesions by LITT or RS. Functional outcomes were graded relative to pre-treatment symptoms and categorized as improved, stable, or worsened at 30, 90, and 180 days post-LITT/RS.

RESULTS

36 patients were identified with median follow-up of 194 days (IQR 72-503), age 64 years (57-72), and estimated baseline KPS 80 (80-90). 35 (98%) had pre-treatment weakness or motor seizure; 15 (42%) received LITT and 21 (58%) RS; all RS were performed with intra-operative motor mapping while LITT were not. All LITT patients were treated for RP lesions (radiation necrosis (RN) or disease progression) vs. 24% of RS patients (p< 0.01). LITT patients trended towards smaller lesions (1.9 cm vs 2.7 cm, p=0.03) and were more likely to show RN (67% vs 5%, p< 0.01) and be discharged home (87% vs 52%, p=0.04), with shorter ICU (0 vs 1 day, p< 0.01) and hospital stays (1 vs. 2 days, p< 0.01). At 30 days, 89% of surviving patients who received RS had stable or improved symptoms, compared to 46% of the LITT cohort (p=0.02). At 90 days, the difference was 88% to 50% (p=0.07), and at 180 days 100% to 80% (p=0.2941).

CONCLUSIONS

In the short term (30 days), patients with PMC lesions have better functional outcomes when treated with RS compared to LITT, while those who survive to the 180-day timepoint experience similar outcomes. These differences are likely due to transient, expected post-LITT edema that subsides with time. Taken together, prognosis and patient priorities are important considerations in the decision between LITT and RS.