bluuebunny/crossref_metadata_2025_split huggingface dataset:
DDEL-08. NOVEL COMBINATION THERAPY USING PI3KINASE INHIBITION AND IMMUNE BASED THERAPY FOR THE TREATMENT OF GLIOBLASTOMA MULTIFORME
Authors: Fonkem Ekokobe , Rogers Karen newell , Tobin Richard , Das Mita , Bowen Sara , Tadipatri Ramya , Healey Debbie , Quarles Christopher , Clark John 
Published: November 2022

Abstract
Hurdles to effective treatments for glioblastoma multiforme (GBM), the most aggressive form of brain cancer, are resistance to chemotherapy, radiation, and immune checkpoint inhibitors. GBMs, like other “difficult to treat” tumors, often over-utilize the phosphatidyl inositol 3 kinase (PI3K) pathway for survival, cell growth, and cell division, conferring both chemotherapy and radiation resistance. Furthermore, the PI3K pathway has been shown to modulate expression of Major Histocompatibility Complex (MHC) molecules, key components of immune recognition. Based on these observations, we examined the potential of a novel, small molecule PI3K inhibitor GCT.Glio.1 (NPT520-337), which was designed to cross the blood brain barrier, to increase the sensitivity of GBM to immune based therapies and radiation. We hypothesized that targeting PI3K would result in growth arrest and increase cell surface expression of MHC molecules and the PD-L1 checkpoint target. Treatment of GL261 mouse and human U251 GBM cell lines with GCT.Glio.1 caused growth arrest at the G2/M checkpoint, increased the cell surface expression of PD-L1 and MHC class II, and synergized with radiation to cause growth arrest and cell death. Based on these results we designed and performed in vivo animal studies, implanting luciferase-flagged GL261 into the caudate nucleus of C57BL6 mice. We treated the animals orally with GCT.Glio.1 followed 24 hours later by anti-PD1 therapy in repeating cycles. The treatments significantly delayed progression of the tumor when compared to no treatment or either treatment alone, with several animals exhibiting complete regression as measured by MRI and bioluminescence. In conclusion, these results indicate that GCT.Glio.1 may sensitize GBM to immune checkpoint inhibitor and/or radiation therapies. Based on our encouraging pre-clinical data and early results from pre-clinical pharmacology and safety studies, we anticipate filing a pre-Investigational New Drug application (pre-IND) as the next step toward our goal of a clinical trial using this combination therapy.
DDEL-19. TREATMENT ADHERENCE OF SELUMETINIB AMONG PATIENTS DIAGNOSED WITH NEUROFIBROMATOSIS TYPE I AND PLEXIFORM NEUROFIBROMA IN THE UNITED STATES
Authors: Yang Xiaoqin , Gao Chi , Ahsan Sama , Dettling Theresa , Gu Yuqian , Banatwala Azeem , Cheng Wendy 
Published: November 2022

Abstract

INTRODUCTION
Selumetinib is the only FDA-approved (April 2020) treatment for pediatric patients with neurofibromatosis type 1 (NF1) and symptomatic inoperable plexiform neurofibroma (PN). Real-world information on selumetinib treatment patterns is lacking. Our study assessed treatment adherence among pediatric patients prescribed selumetinib using a large health claims database.

METHODS
Eligible patients aged 2-21 years with ≥ 1 selumetinib prescription fill in 4/2019-1/2022 (1st fill defines index date), ≥ 6 months of eligibility pre index (baseline), ≥ 3 months of eligibility post index (observation period) and no clinical trial participation were identified from the Clarivate® DRG® Real World Data Repository. Baseline patient characteristics were summarized. Adherence to selumetinib during observation period was evaluated using medication possession ratio (MPR) among patients with ≥ 2 prescription fills and proportion of days covered (PDC) over fixed time periods. Proportion of adherent patients (≥ 80% MPR or PDC) were reported.

RESULTS
73 eligible patients were identified with mean age of 13.0 (standard deviation [SD]: 4.7) years, 54.8% male, 65.8% with commercial insurance, and 31.5% with Medicaid. The most common baseline treatment was pain medication (23.3%). The mean (SD) Quan Charlson Comorbidity Index was 0.9 (1.3) and the most common NF1 PN-related comorbidities were attention-deficit hyperactivity disorder (11.0%) and headaches (6.8%). The mean (SD) MPR was 86.0% (19.8%) and 71.2% of patients were adherent (MPR ≥ 80%). At 60, 90 and 120 days, the mean PDC was 79.6%, 73.0% and 68.4%, respectively; and the proportion of adherent patients (PDC ≥ 80%) was 56.2%, 56.2% and 48.6%, respectively. Analyses assessing PDC at 150 and 180 days indicated slightly under half of patients remained adherent.

CONCLUSION
Mean adherence to selumetinib was high; about half to three-quarters of NF1 PN pediatric patients were adherent to selumetinib--a clinically important finding given the generally low medication adherence rates in pediatric patients.
DDDR-06. NEUROFIBROMATOSIS TUMOR SUPPRESSORS COOPERATIVELY DRIVE TUMOR DE-DIFFERENTIATION AND MEK INHIBITOR RESISTANCE IN PERIPHERAL NERVOUS SYSTEM TUMORS
Authors: Vasudevan Harish , Payne Emily , Delley Cyrille , Sale Matthew , Liu S John , Lastella Sydney , Lucas Calixto-Hope , Eaton Charlotte , Casey-Clyde Tim , Magill Stephen , Chen William , Reddy Alyssa , Braunstein Steve , Perry Arie , Jacques Line , Pekmezci Melike , Abate Adam , McCormick Frank , Raleigh David 
Published: November 2022

Abstract
Schwann cell derived tumors comprising schwannomas, neurofibromas, and malignant peripheral nerve sheath tumors (MPNSTs) are the most common cancers of the peripheral nervous system and often arise in patients with neurofibromatosis type-1 (NF-1) or type-2 (NF-2). NF-1 is caused by loss of NF1, a negative regulator of Ras signaling, and NF-2 is caused by loss of NF2, a pleiotropic tumor suppressor with numerous functions including inhibition of PAK signaling. However, whether functional interactions exist between the NF1 and NF2 tumor suppressors remain unclear. More broadly, there are currently no effective molecular therapies for patients with Schwann cell tumors beyond the MEK inhibitor selumetinib to treat neurofibromas in patients with NF-1. Here, we integrate DNA methylation profiling, whole exome sequencing, bulk and single-cell RNA sequencing, biochemistry, and pharmacology across human samples, cell lines, and mouse xenografts to identify cellular de-differentiation as a driver of malignant transformation and selumetinib resistance. Single nuclear RNA-sequencing of human neurofibromas (n = 3) or MPNSTs (n = 3) revealed a total of 13 cell types with increased proliferating, de-differentiated tumor cell populations in MPNST samples. Single cell RNA-sequencing of MPNST mouse xenografts revealed persistence of de-differentiated cell populations in selumetinib treated samples compared to vehicle control, suggesting cellular de-differentiation underlies treatment resistance. A genome-wide CRISPRi screen for mediators of selumetinib response in NF1 deficient neurofibroma cells revealed NF2 loss drives selumetinib resistance. Consistently, NF2 suppression in NF1 deficient neurofibroma cells caused Schwann cell de-differentiation and activation of PAK, a serine threonine kinase. Translationally, a small molecule PAK inhibitor in combination with selumetinib formed an effective therapy in mouse MPNST xenografts. In sum, we elucidate a paradigm of de-differentiation driving malignant transformation and treatment resistance in Schwann cell tumors, uncovering a functional link between the NF1 and NF2 tumor suppressors that sheds light on a novel therapeutic vulnerability.
DDDR-10. INHIBITING INSULIN SIGNALING REVERSES RESISTANCE TO PI3K-MTOR INHIBITORS IN AGGRESSIVE PEDIATRIC HIGH-GRADE GLIOMAS
Authors: Gatesman Taylor , Halligan Katharine , Halbert Matthew , Stanton Ann-Catherine , Cruz Andrea , Golbourn Brian , Pollack Ian F , Mack Stephen C , Agnihotri Sameer 
Published: November 2022

Abstract
Primary central nervous system (CNS) tumors are now the most common cause of childhood cancer–related deaths. Pediatric high-grade gliomas (pHGGs) are among the most lethal brain tumors with a 5-year survival rate of only 20%. MYCN pHGGs represent one subgroup with an unmet need for therapeutics. MYCN belongs to the family of MYC transcription factors that regulate numerous cancer hallmarks such as proliferation, apoptosis, and metabolism. While no direct inhibitors of MYCN are in clinical trial, current strategies focus on targeting the MYCN mediated transcriptional machinery or cell cycle regulators. Lack of relevant pHGG models for pre-clinical testing contribute to limited therapeutic efficacy. To address these knowledge gaps, we developed a novel mouse model of MYCN pHGG using the FLEx-Cre switch system, whereby neural stem cells are selectively delivered with MYCN cDNA and shRNA targeting the tumor suppressor genes p53 and Pten and form tumors in vivo. We identified that this model harbors hyper-activation of the PI3K/AKT/mTOR signaling pathway. We demonstrate that dual PI3K-mTOR blood brain barrier penetrant inhibitors are effective in reducing pHGG growth and MYCN protein levels. Because treatment-resistance is a fundamental feature of pHGGs, we developed a novel drug-resistance model of MYCN pHGG as a mechanistic tool to identify relevant resistance mechanisms. Using transcriptome analysis, we identified the insulin growth factor signaling pathway as our top mechanism of resistance. We hypothesized that MYCN is a critical driver of pHGG and can be effectively targeted via dual inhibition of PI3K-mTOR and IGF/Insulin signaling pathways. We tested next generation inhibitors of IGF and PI3K/mTOR pathways and performed genetic and pharmacological assays in our MYCN pHGG and human MYCN pHGG cells. Inhibition of both pathways in our MYCN pHGG model and human MYCN cells were synergistic, leading to significant decreases in cell growth and MYCN signaling.
DDDR-11. TREATING DIPG WITH A MITOCHONDRIALLY TARGETED PLATINUM(IV)-BASED PRODRUG
Authors: Raghavan Sudhir , Sharpe Martyn , Baskin David 
Published: November 2022

Abstract

Diffuse intrinsic pontine glioma (DIPG) is a universally fatal childhood cancer of the brain with 5-year survival rates of &lt; 2%. Despite the introduction of conventional chemotherapy and radiotherapy, improvements in survival have been marginal and long-term survivorship is rare. We previously developed MP-Pt(IV), monoamine oxidase B (MAOB) sensitive, mitochondrial targeting platinum-(IV) based prodrug derived from the chemotherapeutic cisplatin. MP-Pt(IV) is well tolerated and is highly effective in a mice xenograft GBM brain tumour model. Unlike in GBM, the expression levels of MAOB in DIPG are unknown. We tested MP-Pt(IV) against DIPG to test whether DIPG exhibit a similar sensitivity to mitochondrially targeted Pt(IV)-based prodrugs.

METHODS
In-vitro cell growth inhibition studies were conducted on DIPG cells using MP-Pt(IV). Labeling studies were carried out with MitoSox, MitoTracker, and H2DCFAM. Oxygen consumption studies were performed to show mitochondrial targeting. Clonogenic survival assay and scratch assay were performed.

RESULTS
MP-Pt(IV) shows potent growth inhibition of DIPG in cell culture studies. Mechanistic studies indicate mitochondrial targeting of the prodrug. Significant increases in cellular super-oxide and hydrogen peroxide levels are observed upon MP-Pt(IV) treatment. Oxygen consumption studies confirm mitochondrial targeting of MP-Pt(IV). MP-Pt(IV) strongly inhibits clonogenic survival and cell migration in treated cells.

CONCLUSIONS
We demonstrate that MP-Pt(IV) is highly effective in DIPG in vitro and is a good candidate for testing in a DIPG xenograft animal model and further development.
DDDR-16. GBP3-STING INTERACTION IN GLIOBLASTOMA COORDINATES AUTOPHAGY, ANTI-OXIDATIVE, AND DNA REPAIR PROGRAMS IN RESPONSE TO TEMOZOLOMIDE
Authors: Li Ming , Chen Clark 
Published: November 2022

Abstract

INTRODUCTION
Guanylate-binding proteins (GBPs) are a group of dynamin-related large (~65 kDa) GTPases expressed in response to interferon and mediate intracellular immunity. In contrast to the Ras- or Rho family of small GTPases (~20 kDa) or the trimeric GTPases, little is known about the function of GBPs beyond their role in innate cellular immunity.

METHODS
Informatic analysis of clinically annotated glioblastoma datasets, laboratory studies of protein-protein interaction, functional characterization after depletion or exogenous expression

RESULTS
Of the seven known members of human GBPs, only GBP3 showed significant up-regulation in response to temozolomide, the standard-of-care DNA-alkylating chemotherapy for glioblastoma. Importantly, high levels of glioblastoma GBP3 expression was associated with worsened survival after temozolomide treatment. Consistent with this observation, exogenous expression of GBP3 induced temozolomide resistance in independent patient-derived glioblastoma neurosphere lines, while GBP3 silencing conferred temozolomide sensitivity, both in vitro and in vivo. This sensitivity was associated with the accumulation of cytoplasmic DNA fragments, suggesting the involvement of STING. Supporting this hypothesis, the N-terminal of GBP3 physically interacted with STING to prevent proteasome-mediated degradation of STING. Since cytoplasmic DNA bound STING activates key transcriptional programs, we profiled transcription programs requiring both GBP3 and STING expression and identified an autophagy program mediated by p62 (autophagy), a defense program against oxidative insults mediated by nuclear factor erythroid 2 like 2 (NFE2L2, NRF2), and a DNA repair program mediated by O6-methylguanine-DNA-methyltransferase (MGMT). These programs were previously shown to play central roles in cellular resistance to DNA alkylating agents.

CONCLUSION
In addition to its central role in innate immunity, GBP3 mediates cellular response to DNA damage through coordination of autophagy, anti-oxidative, and DNA repair programs.
DDDR-18. COMPREHENSIVE PROTEOMIC PROFILING OF BRAFV600E GLIOMA CELLS SHOWS UPREGULATION OF GLYCOLYSIS AND TCA CYCLE PROTEINS AFTER COMBINED MTOR AND MAP KINASE PATHWAY BLOCKADE
Authors: Alaali Lujain , Raabe Eric , Maxwell Micah , Eberhart Charles , Zhang Hui 
Published: November 2022

Abstract
Low-grade gliomas (LGG) are slow-growing tumors that affect neurologic function by pressing on the surrounding parts of the brain. Pediatric low-grade glioma (pLGG) is the most common childhood brain tumors. Patients with pLGG often have a significant life-long disabilities. The most common mutations in pLGG are in the mitogen-activated protein kinase (MAPK) pathway including tumor suppressor neurofibromin (NF1), and the oncogene BRAF. BRAF activates MEK1/2, which activates of ERK1/2, leading to tumorigenesis. BRAFV600E mutation results in the activation segment of the kinase “monomeric form of BRAF”, leading to constitutive activation of MAP kinase and mTOR pathways Combination treatment of TAK228 (mTOR inhibitor) and trametinib (MEK1/2 inhibitor), suppressed both mTOR and MAP kinase pathways and inhibited BRAFV600E glioma tumor growth. To further investigate and understand the molecular mechanism of TAK228 and trametinib combinatorial efficacy, we performed comprehensive proteomic analysis of BRAFV600E glioma tumors treated with TAK228 and trametinib. We found increased levels of many proteins in the glycolysis and TCA cycle. Specifically we found increases at the protein level in citrate synthase, aconitase and malate dehydrogenase in the TCA cycle. In glycolysis, we observed increased glucose transporter expression (SLC2A1), increased hexokinase 2, and increased GAPDH. Upregualtion of these proteins may represent attempts to bypass the effects of mTOR and MAP kinase blockade on the activity of these pathways. We are currently performing flux metabolic profiling using uniformly labeled glucose to assess the activity of the pathways after combined mTOR and MAP kinase blockade. Our results may increase our understanding of how glioma cells use glucose and how mTOR and MAP kinase pathway inhibition affects basic metabolic pathways in glioma cells.
DDDR-19. NEXT-GENERATION PI3K INHIBITOR FOR GLIOBLASTOMA TREATMENT
Authors: Hutchings Kasen , Pridham Kevin , Liu Min , Sheng Zhi 
Published: November 2022

Abstract
High-grade gliomas are especially problematic because of the limited treatment options available to patients. The phosphoinositide 3-kinase (PI3K) pathway has become a significant research target within the field of cancer drug discovery due to the pathway’s promotion of cell proliferation and inhibition of apoptosis. While many new PI3K inhibitory medications show promise in preventing cancer growth, many are toxic because they inhibit multiple PI3K catalytic subunit isoforms making these drugs ineffective treatment options. Our novel peptide drug, Selectide-18, overcomes this toxicity by specifically targeting the p110β isoform of PI3K, which was shown to be the most impactful isoform in many cancer types, including several high-grade gliomas. We designed Selectide-18 after discovering an 18-residue motif unique to p110β. Selectide-18 is a mimetic peptide modeled after this motif. Our in silico analyses show that our drug works by binding to the PI3K regulatory subunit, p85α, thus preventing the binding of catalytic subunit p110β and leaving PI3K inactive. These findings were supported by coimmunoprecipitation. Using a PI3K cell-free kinase assay, we confirmed that our drug specifically targets p110β and does not inhibit p110α, p110δ, or p110γ. The IC50 of Selectide-18 was determined to be approximately 100nM using the same PI3K cell-free kinase assay. We tested several drugs in an MTS viability assay, including Selectide-18, a scrambled 18-residue negative control peptide, and PI3K inhibitor GSK2636771 to compare levels of cancer cell viability. Selectide-18 successfully killed glioblastoma cells within lines with high p110β activity. The drug had no effect in cell lines with low p110β activity. In conclusion, Selectide-18 is explicitly tailored for p110β-high gliomas and has shown promise to treat high-grade glioma effectively. We believe this model of peptide drug can usher in a new generation of p110β specific PI3K inhibitors.
DDDR-20. TARGETING THE SELECTIVE VULNERABILITY OF IDH-MUTANT GLIOMA WITH ZOTIRACICLIB
Authors: Pang Ying , Yu Guangyang , Ranjan Alice , Wang Herui , Sergi Zach , Kim Olga , Merchant Mythili , Zhang Meili , Song Hua , Zhang Wei , Davis Dionne , Gilbert Mark , Liu Zhenggang , Wu Jing 
Published: November 2022

Abstract

BACKGROUND
IDH mutations are common in diffuse gliomas and confer an increased dependency on oxidative mitochondrial function. Zotiraciclib, a multi-kinase inhibitor, not only suppresses CDK9-mediated gene transcription process but also causes mitochondrial dysfunction in preclinical models. We investigated the selective activity of zotiraciclib in IDH-mutant gliomas.

METHODS
Cytotoxicity of zotiraciclib was determined in patient-derived glioma cells with/without IDH mutations. Immunoblotting and flow cytometry were used to evaluate the cell death pathways. Real-time ATP production was measured by Seahorse assay.

RESULTS
The EC50 of zotiraciclib in IDH-wt cells was twice as high as in IDH-mutant cells. In low-dose zotiraciclib (15nM)-treated IDH-mutant cells, RNA Pol II phosphorylation and expression of antiapoptotic proteins, including XIAP, MCL-1 and survivin were decreased significantly. Cleaved caspase 3/7, 8, 9 and LC3B were also detected in treated IDH-mutant cells but not in IDH-wt cells, suggesting activation of intrinsic and extrinsic cell apoptosis pathways, and subsequent autophagy of IDH-mutant cells. Low-dose treated IDH-mutant, but not IDH-wt cells, induced decreased expression of a panel of mitochondrial respiration genes, and mitochondrial respiration complexes, cellular ATP depletion and increased ROS production, suggesting a greater disruption of mitochondrial function in zotiraciclib-treated IDH-mutant cells. Zotiraciclib treatment prolonged the survival in mice bearing intracranial IDH-mutant gliomas (30 days in DMSO-treated group vs 33 days in zotiraciclib-treated group, p = 0.01), but not in mice with glioma established with the isogenic IDH-wt glioma cells (18 days in DMSO-treated vs 20 days in zotiraciclib-treated group, p = 0.10).

CONCLUSIONS
There is selective activity of zotiraciclib in IDH-mutated glioma. Low-dose exposure of zotiraciclib induces cell death and suppresses transcriptional process and mitochondrial biogenesis in IDH-mutant glioma, not in IDH-wt tumors. These findings support a clinical trial testing zotiraciclib in IDH-mutated glioma. The treatment efficacy seen even at low concentrations further supports testing it as a single agent, thereby reducing toxicity concerns.
DDDR-22. TRANSLATION OF THE PDGFRA/KIT INHIBITOR AVAPRITINIB FOR PEDIATRIC HIGH-GRADE GLIOMA
Authors: Mayr Lisa , Trissal Maria , Schwark Kallen , Labelle Jenna , Kong Seongbae , Groves Andrew , Supko Jeffrey , Hack Olivia , Marques Joana , Panditharatna Eshini , Dubois Frank , Greenwald Noah , Bandopadhayay Pratiti , Ligon Keith , Furtner-Srajer Julia , Weiler-Wichtl Liesa , Leiss Ulrike , Rosenmayr Verena , Madlener Sibylle , Stepien Natalia , Lötsch-Gojo Daniela , Dorfer Christian , Dieckmann Karin , Azizi Amedeo , Guntner Armin , Palova Hana , Slaby Ondrej , Pokorná Petra , Beroukhim Rameen , Kramm Christof , Jones David T , Štěrba Jaroslav , Mullauer Leonhard , Haberler Christine , Perez Nisha , Kim Sean , Hsieh Anthony , Dimitrijevic Sasa , Skrypek Mary , Martinez Nina , Bowers Daniel , Filbin Mariella , Gojo Johannes , Koschmann Carl 
Published: November 2022

Abstract
Pediatric high-grade glioma (pHGG) is an incurable disease with a median survival of less than 6 months post-progression and no effective targeted therapy. PDGFRA is commonly altered in pHGG, but targeting PDGFRA in this disease has been unsuccessful, likely due to poor central nervous system (CNS) penetrance. Avapritinib is a novel and CNS-penetrant PDGFRA/KIT inhibitor that is FDA-approved for adults with unresectable or metastatic PDGFRA exon 18-mutant gastrointestinal stromal tumor (GIST) and is being studied in CNS tumors. We performed a pre-clinical and clinical assessment to determine the potential suitability of avapritinib therapy in PDGFRA-driven glioma. A multi-institutional cohort genetic analysis revealed PDGFRA amplification and mutation in 10.2% and 6.1% of pHGG, respectively. Additionally, PDGFRA expression in the absence of genetic events was significantly increased in H3K27-altered diffuse midline glioma (DMG) compared to H3-wildtype pHGG. Avapritinib performed well in: (i) mutant PDGFRA enzyme inhibition and wildtype inhibition at high dose, (ii) minimal off-target kinase inhibition, (iii) brain penetration (peak 10 µM), and (iv) proliferation/pPDGFRA reduction in PDGFRA-amplified and mutant pHGG cell lines. Avapritinib treatment in an aggressive PDX model of pHGG resulted in significant survival benefit. We pursued treatment of eight pediatric and young adult HGG patients with avapritinib across seven institutions. Patients were a mixture of local (N = 4) and metastatic disease (N = 4); all patients were post-initial radiation, with 7/8 having progressed on prior treatment. 7/8 patients had PDGFRA amplifications or mutations, and 7/8 had H3K27M mutations. Therapy was generally well-tolerated. 4/8 patients showed radiographic response to avapritinib, with one patient demonstrating complete response of target lesion and remains on therapy. Avapritinib levels in patients’ CSF and brain tumor tissue reached micromolar levels. These results demonstrate that avapritinib is a potent, selective, and CNS-penetrant PDGFRA/KIT inhibitor that is promising for further study in pHGG with relevant alterations.