bluuebunny/crossref_metadata_2025 huggingface dataset:
SURG-30. SURGICAL RESECTION OF PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA: IMPACT OF PATIENT SELECTION ON OVERALL SURVIVAL
Authors: Schellekes Nadav , Barbotti Arianna , Abramov Yael , Sitt Razi , Meco Francesco Di , Ram Zvi , Grossman Rachel
Published: December 2020

OBJECTIVE

A possible prolonged survival after surgical resection for primary central nervous system lymphoma (PCNSL) lesions in selected patients has been suggested, but selection criteria for surgery, especially for solitary lesions, have never been established.

METHODS

We retrospectively searched our patient database for records of adult patients (≥18 years) who were diagnosed and treated for a solitary lesion of PCNSL between 2005 and 2019. Patients were divided into groups according to whether they underwent surgical resection or needle biopsy. Statistical analyses were performed in an attempt to identify variables affecting outcome and possible survival advantage and to characterize subgroups of patients who would benefit from resection of their tumor compared to undergoing biopsy only.

RESULTS

113 patients with a solitary lesion of PCNSL were identified, 36 underwent surgical resection and 77 a diagnostic stereotaxic biopsy only. Pre-operative risk factors were found to include age > 70 years ([HR] 9.61, 95% [CI] 2.42-38.11, p=0.001) and deep seated lesions (adjusted HR 3.33, 95% CI 1.13-9.84, p=0.030). Having a postoperative Karnofsky Performance Scale (KPS) under 80 (adjusted HR 3.21, 95% CI 1.05-9.77, p=0.040) or surgical-site infections (adjusted HR 4.27, 95% CI 1.18-15.47, p=0.027) were significant postoperative risk factors. In a subgroup analysis, patients with a superficial tumor who underwent surgical resection had significantly longer survival times compared with those who underwent needle biopsy (median survival 34.3 months versus 8.9 months, p=0.014). Patients under 70 years who had a superficial tumor and underwent surgical resection had significantly prolonged survival, with a median survival of 35.0 months versus 8.9 months in patients from the same group who underwent needle biopsy (p=0.007).

CONCLUSION

Specific subgroups of patients with a solitary PCNSL lesion might gain a survival benefit from surgical resection compared to undergoing only a diagnostic biopsy.
SURG-31. SURGICAL OUTCOME ANALYSES ON 244 CENTRAL NERVOUS SYSTEM HEMANGIOBLASTOMA
Authors: Takami Hirokazu , Burns Terry C , Parney Ian
Published: December 2020

BACKGROUND

Surgical resection of the central nervous system hemangioblastoma is often challenging, with vascular-rich nature and surrounding critical structures. von Hippel-Lindau (VHL) disease cases make the management more difficult with repeated surgeries required for multiple lesions. Here we investigated the surgical outcome of CNS HGBs on a large cohort to clarify the clinical and radiological parameters pertaining to the surgical success.

METHODS

Retrospective analysis of consecutive, neurosurgically managed CNS HGB at Mayo Clinic, 1988-2018.

RESULTS

Total 244 surgeries were performed for 172 patients. Gross total resection (GTR) was achieved in 90.0%, which was lower in cases brainstem lesions (78.3%) and was associated with the tumor, especially solid-portion volume (p=0.017). Intraoperative blood loss correlated with the size of solid portions, and the transfusion was performed in 7.5%. Postoperative complication was observed in 52.2%, including new/worsening neurological deficit in 45.4%, wound complication in 9.1% and systemic complication in 4.0%. Postoperative rehabilitation was introduced in 61.7% of the patients, which was statistically associated with age, non-GTR and tumor location (brainstem and spine) on multivariate analysis (p=0.0031, 0.027 and 0.0066, respectively). Treatment-free survival was longer in VHL (vs sporadic) cases and GTR (vs non-GTR) cases, and multivariate analysis showed GTR was the only factor associated with treatment-free survival (p=0.0015).

CONCLUSIONS

Surgery for CNS HGBs was shown to be challenging, with abundant intraoperative bleeding and high risk of postoperative complications necessitating rehabilitation. GTR of the lesion is of utmost importance, which increases the chance of long treatment-free survival as well as favorable direct postoperative clinical course.
TAMI-14. NANOPARTICLE DELIVERY OF PD-L1 CRISPR/CAS9 PLASMID DNA FOR ANTI-GLIOBLASTOMA IMMUNOTHERAPY
Authors: Fierro Javier , Tran An , Factoriza Chris , Chin Brandon , Dou Huanyu
Published: December 2020

Glioblastoma multiforme (GBM) is a devastating cancer that develops from astrocytes in the brain. GBM is fast acting and kills 90% of patients within 5 years. Several immunotherapies have been developed to treat GBM, however, major challenges still persist. For example, checkpoint proteins such as programmed cell death protein 1 (PD-1) and its ligand, programmed death ligand 1 (PD-L1), are upregulated in GBM cells to evade the immune system. Targeting PD-L1 for genetic knockdown is thus a promising avenue for the treatment of GBM. However, PD-L1 protein inhibitors have been shown to cause immune overreaction and toxicity, therefore requiring new technologies. CRISPR/Cas9 gene editing has been widely used for the study and treatment of many diseases, but has not been extensively studied for the treatment of GBM. The main challenge is developing a gene delivery platform for the delivery of CRISPR/Cas9 plasmid DNA (pDNA). Many viral vectors have been used for the delivery of pDNA, but unfortunately are associated with high toxicity. Nanotechnology is emerging as a new platform for the delivery of pDNA as it shows high transfection efficiency with low cytotoxicity. We developed a cationic core-shell nanoparticle (NP) capable of carrying CRISPR/Cas9 pDNA. This plasmid contains multiple guide RNA (gRNA) expression cassettes for the knockdown of PD-L1. PDL1gRNA-CRISPR/Cas9pDNA-NPs were taken up by U87 cells within 30 minutes, and entered into the nucleus at 2 hours. The effective delivery of PDL1gRNA-CRISPR/Cas9pDNA-NPs led to the expression of PD-L1 gRNA and Cas9 enzyme, and the knockdown of PD-L1. Regulation of immune balance was determined after PD-L1 knockdown in vitro and in vivo. Our study shows the potential of NP-based PDL1gRNA-CRISPR/Cas9 delivery as an anti-GBM immunotherapy for clinical applications.
TAMI-30. LOCAL TARGETING OF NAD+ SALVAGE PATHWAY ALTERS THE IMMUNE TUMOR MICROENVIRONMENT AND ENHANCES CHECKPOINT IMMUNOTHERAPY IN GLIOBLASTOMA
Authors: Li Ming , Kirtane Ameya , Kiyokawa Juri , Nagashima Hiroaki , Traverso Giovanni , Cahill Daniel , Wakimoto Hiroaki
Published: December 2020

The aggressive primary brain tumor glioblastoma (GBM) is characterized by aberrant metabolism that fuels its malignant phenotype. Diverse genetic sub-types of malignant glioma are sensitive to selective inhibition of the NAD+ salvage pathway enzyme nicotinamide phosphoribosyltransferase (NAMPT). However, the potential impact of NAD+ depletion on the brain tumor microenvironment has not been elaborated. In addition, systemic toxicity of NAMPT inhibition remains a significant concern. Here, we show that microparticle-mediated intratumoral delivery of NAMPT inhibitor GMX1778 induces specific immunological changes in the tumor microenvironment of murine GBM, characterized by upregulation of immune checkpoint PD-L1, recruitment of CD3+, CD4+ and CD8+ T cells and reduction of M2-polarized immunosuppressive macrophages. NAD+ depletion and autophagy induced by NAMPT inhibitors mediated the upregulation of PD-L1 transcripts and cell surface protein levels in GBM cells. NAMPT inhibitor modulation of the tumor immune microenvironment was therefore combined with PD-1 checkpoint blockade in vivo, significantly increasing the survival of GBM bearing animals. Thus, the therapeutic impacts of NAMPT inhibition extended beyond neoplastic cells, shaping surrounding immune effectors. Microparticle delivery and release of NAMPT inhibitor at the tumor site offers a safe and robust means to alter an immune tumor microenvironment that could potentiate checkpoint immunotherapy for glioblastoma.
TAMI-35. AUTOPHAGY MEDIATED LIPID CATABOLISM FACILITATES GLIOMA PROGRESSION TO OVERCOME BIOENERGETIC CRISIS
Authors: Wang Chenran , Haas Michael , Yeo Syn , Paul Ritama , Yang Fuchun , Vallabhapurapu Subrahmanya , Qi Xiaoyang , Plas David R , Guan Jun-Lin
Published: December 2020

Activation of mTORC1 plays a significant role in cancer development and progression. However, the metabolic mechanisms to sustain mTORC1 activation in stressed cancer cells are still underappreciated. Autophagy, one downstream process of mTORC1, is proposed to be suppressed under the condition of mTORC1 hyper-activation. Interestingly, we recently revealed higher autophagy activity in various Tsc-deficient tumor cells with mTORC1 hyper-activity. Nevertheless, the functions and mechanisms of autophagy in regulating mTORC1 in cancer cells are not well understood. In this study, we revealed a strong association of altered mRNA levels in mTORC1 upstream and downstream genes with poor prognosis of glioma patients. Our metabolic and molecular studies indicated that autophagy mediated lipid catabolism was essential to sustain mTORC1 activity in glioma cells under energy stresses. We found that autophagy inhibitors or fatty acid oxidation (FAO) inhibition in combination with 2-Deoxy-D-glucose (2DG) decreased oxidative phosphorylation, ATP production, mTORC1 activity, and survival of glioma cells in vitro. Consistently, the combination of chloroquine (CQ) or FAO inhibitors with 2DG effectively suppressed the progression of xenografted glioma with mTORC1 hyperactivation in mice. This study established a novel autophagy/lipid degradation/FAO/ATP pathway that maintains high mTORC1 signaling and tumor progression in brain cancer cells under energy stresses. The requirement of lipophagy in brain cancers may provide an opportunity to develop new molecular therapeutic targets to counteract mTORC1 for tumor progression.
TAMI-40. TUMOR MICROBIOME AND GLIOBLASTOMA (GBM)
Authors: Yust-Katz Shlomit , Gigi Elinor , Rosenberg Deborah , Kanner Andrew A , Laviv Yoseph , Benouaich-Amiel Alexandra , Siegal Tali , Barda Adva Levi , Straussman Ravid
Published: December 2020

Bacteria have been found to play major roles in many physiologic/disease processes including cancer. The presence of bacteria within brain tumors has never been explored. The aim of this study was to examine the microbiome of Glioblastoma. A cohort of 40 glioblastoma samples (FFPE), from two medical centers served for DNA extraction using a specialized extraction protocol that includes a bead beating step to ensure complete bacterial DNA recovery. A set of negative controls was introduced at different steps of the assay to identify and monitor contaminating bacterial DNA. We measured the levels of bacterial DNA in the samples using a RT-qPCR assay, amplifying the bacterial 16S rRNA gene and detected bacterial DNA in over 40% of the samples. To characterize the bacterial taxa that are present in GBM tumors, we applied 16S DNA sequencing on the samples. After implementing a stringent set of filters on the sequencing data, eliminating contaminating signal, we detected a total of 22 bacterial taxa in GBM tumors. To visualize bacteria in GBM tissues and learn about their localization within the tissue we used immunohistochemistry staining with anti-lipopolysaccharide (LPS) and anti-lipoteichoic acid (LTA) antibodies detecting gram negative and gram positive bacteria (correspondingly). Bacteria were also visualized by staining bacterial RNA using a 16S rRNA in situ hybridization assay. Staining of a human GBM tissue microarray (TMA) containing 32 cases of GBM showed that the majority of cases stained positive for LPS and ~40% were positive for 16S rRNA staining. Bacterial LPS and 16S rRNA were localized mainly inside the tumor cells. Our study demonstrates, for the first time, that bacteria or bacterial components are present in human Glioblastoma tumors. We are currently expanding our study cohort in order to better define the bacteria found within glioblastoma samples and assess their possible effects
TAMI-47. EVALUATION OF THE EFFECT OF MICROENVIRONMENTAL STRESSES ON GLIOMA STEMNESS IN VITRO AND EX VIVO
Authors: Pantazopoulou Vasiliki , Berg Tracy , Pietras Alexander
Published: December 2020

Glioblastoma is the highest-grade glioma and most aggressive brain tumor, affecting both adults and children. Treatment includes surgery followed by chemotherapy, most frequently in the form of temozolomide treatment, radiation and in some cases by application of tumor-treating fields. Tumor recurrence is very common and is driven by cells exhibiting a treatment-resistant cancer stem cell phenotype, located in specific niches, namely the hypoxic and perivascular niche. While previous studies have delved into the role of the microenvironment in supporting glioma stemness and therapy resistance, little is known about how the stromal cells themselves respond to microenvironmental stresses. Here, we show that one cell type of the tumor microenvironment, the astrocyte, becomes activated after treatment with radiation, temozolomide or hypoxia in vitro, showing an increase in GFAP and Vimentin expression as well as morphological changes. Activated astrocytes also change their secretome, secreting cytokines such as IL6, IL7, CCL2 and CCL8, all associated with worse prognosis in several patient cohorts. Importantly, conditioned medium or extracellular matrix from activated astrocytes induce stemness features in glioma cells, measured by increased side population or radiation resistant fractions. To evaluate our findings in a more relevant model, we use an ex vivo organotypic culture system for brain sections from our experimental mouse model of glioma. Cultures are maintained for up to 21 days in 21%, 5% or 1% O2 with a high proportion of surviving tumor and stromal cells. We intend to use the ex vivo system to evaluate the effect of microenvironmental stresses on glioma stemness. Our study suggests that the tumor microenvironment that has been exposed to stressors such as radiation, chemotherapy or hypoxia is important in maintaining stemness and therefore treatment resistance in glioblastoma. Further research is required to address these stress-induced changes and provide better treatment options for glioblastoma patients.
TAMI-52. G-CSF SECRETED BY EPIGENETICALLY REPROGRAMMED MUTANT IDH1 GLIOMA STEM CELLS, REVERSES THE MYELOID CELLS’-MEDIATED IMMUNOSUPPRESSIVE TUMOR MICROENVIRONMENT
Authors: Alghamri Mahmoud , Avvari Ruthvik , Thalla Rohit , Zhang Li , Ventosa Maria , Taher Ayman , Núñez Felipe , Heth Jason , Orringer Daniel , Lowenstein Pedro , Castro Maria
Published: December 2020

Mutation in isocitrate dehydrogenase (mIDH) is the main genetic lesion that defines clinical glioma subtypes and prognosis. This gain of function mutation is associated with the production of the oncometabolite, R-2-hydroxyglutarate, that inhibits α-ketoglutarate dependent enzymes such as TET2 and the Jumonji-C domain containing demethylases. The resultant epigenetic modifications elicit profound effects on the tumor biology and on the glioma-infiltrating immune cells. Here, we report that in genetically engineered mouse glioma models(1), IDH1 mutation caused an expansion of tumor infiltration granulocytes. Upon phenotypic and functional characterization, we uncovered that granulocytes in mIDH1 glioma express low level of immunosuppressive molecules and did not inhibit T-cell function. Single-cell sequencing revealed that these granulocytes are heterogeneous and composed of three distinct populations; neutrophils, pre-neutrophils, and a small fraction of immunosuppressive PMN-MDSCs. Moreover, primary human gliomas showed a higher cellular fraction exhibiting the PMN-MDSCs gene signature in wtIDH1 tumors than the mIDH1 tumors. The mechanism by which mIDH1 mediates non-immune suppressive granulocytes expansion involves epigenetic reprogramming which leads to enhanced expression of granulocyte colony-stimulating factor (G-CSF) in stem-like cells. High G-CSF gene expression is correlated with favorable patient outcome solely in LGG-astrocytoma with mIDH1. Thus, G-CSF represents a potential therapeutic that can be harnessed to improve immunotherapeutic responses in wild type IDH1 glioma patients.
TAMI-53. THE ONCOMETABOLITE D-2HG INDUCE INFLAMMATORY ASTROGLIOSIS CAUSING NEUROTOXICITY AND SEIZURES IN IDH MUTATED GLIOMA
Authors: Behringer Simon , Ravi Vidhya , Joseph Kevin , Beck Juergen , Schnell Oliver , Heiland Dieter
Published: December 2020

The role of tumor-associated astrocytes in the microenvironment of glioma has long been underestimated but is moving into the focus of current research. We explored the role of reactive astrocytes in IDH-mutated glioma using RNA-sequencing of purified astrocytes and microglia and single-nucleus RNA-sequencing of infiltrating tumor regions. Mapping of the transcriptional phenotype of astrocytes along developmental and reactive trajectories revealed an inflammatory transformation of IDH-mutated associated astrocytes. The major proportion of astrocytes is marked by complement-activation similar to findings in neuroinflammatory diseases. A human neocortical slices model with injected IDH-mutated patient-derived cells or D-2HG treatment (+/- microglia depletion) was used to map shared and unique transcriptional adaptation in astrocytes promoted by either tumor cells or metabolic alteration. High-dimensional electrophysiological profiling was used to investigate alterations in neural response to tumor-induced microenvironmental transformation. We showed that 2HG alone promote the inflammatory pattern of astrocytes, which causes neurotoxicity and seizures in our neocortical slice model. Depletion of microglia rescued the neurotoxicity suggesting that microglia predominantly drive inflammatory astrogliosis as a response to metabolic alteration the tumor environment. We showed that neurotoxic astrogliosis induced by the oncometabolite D-2HG via distinct microglia activation promote the evolution of frequently observed seizures in IDH-mutated glioma patients.
TAMI-64. PHYSICAL STRESSES IN BRAIN TUMORS
Authors: Kumar Ashwin , Nia Hadi , Datta Meenal , Chatterjee Sampurna , Ferraro Gino , Nahed Brian , Jain Rakesh
Published: December 2020

Solid stress, distinct from fluid pressure, is a physical force contained in and transmitted by solid components of the brain tumor, including cells and the matrix they produce. Solid stress has been shown to promote tumor progression, and decrease anticancer therapy efficacy. This is especially relevant in brain tumors, as the rigid skull results in these trapped forces, increasing intracranial pressure, and potentially leading to other complications, including neuronal cell death. Here we present a novel method of quantifying these physical stresses in situ in both mice (glioblastoma [U87], brain metastasis [BT474], and ependymoma models) and patients. Briefly, following a craniotomy, mechanical forces that include solid stress are released, which causes the tissue to deform in peaks (areas under compression) and valleys (areas originally under tension). This tissue deformation is imaged via high-resolution ultrasound, and analysed via custom code to produce an accurate 3D model of the entire mouse brain, including the tumour region. For human samples, a pre-operative MRI is used to generate a detailed 3D model of the human brain. During surgery, the trapped physical stresses results in a bulge of the dura post craniotomy, which is mapped via Brainlab. These deformations are analysed in an identical fashion to the murine model. We further show that in the brain metastases model, chemotherapy reduces compression stresses by 51%. Further, our technique results in fast processing time (~ 15 minutes), and has the potential to prevent the need for intraoperative MRI based on position simulations. As such, solid stress measurements provide a new class of mechanical biomarkers that can be correlated to clinical outcomes for predictive and prognostic value.
TMOD-06. MALIGNANT TRANSFORMATION OF PLEXIFORM NEUROFIBROMAS IN AN NF1 MUTANT MOUSE MODEL OF SPINAL IRRADIATION
Authors: Nakamura Jean , Laurent Danny , Smith Abbi , Bessler Waylan , Clapp Wade , Horvai Andrew
Published: December 2020

PURPOSE

Understanding the relationships between ionizing radiation (IR) and carcinogenesis, as well as other variables, including genetic background and sex, may minimize risks of transformation from benign to aggressive cancers while maintaining treatment efficacy. We aim to understand the relationship between IR, tumor microenvironments, and effect of sex on malignant transformation using a conditional knockout mouse model of Neurofibromatosis type 1 (NF1).

METHODS

Conditional knockout mouse models of plexiform neurofibromas (PeriCre+; Nf1fl/fl and PeriCre+; Nf1fl/-, n = 172) were treated with 0 Gy; 3 Gy x 5; 3 Gy x 10 of focal, fractionated spinal irradiation (SI) and aged until signs of illness. Histopathological analysis was performed on images from H&E-stained FFPE peripheral nerve tissues.

RESULTS

SI affected the survival of mice in a dose-dependent manner, with a significant decrease at 30Gy (median survival 254 and 218 days for 0 Gy and 30 Gy, p < 0.01, Log-rank test). Male mice had reduced overall survival at 15 and 30 Gy (median survival 368, 278 and 245 days for 0, 15 and 30Gy, p < 0.01, Log-rank test), but not in female mice, indicating sex-specific radiosensitivity. Differences in tumour microenvironments did not affect mouse survival after SI. Histopathological analysis is ongoing (43 out of 76 FFPE samples analyzed). Preliminary findings showed a total of 43 malignancies ranging from plexiform neurofibromas (PNs) to high-grade malignant peripheral nerve sheath tumours (MPNSTs). Increasing histologic aggressiveness was observed in higher SI doses, with high-grade MPNST (2.3%) exclusively found in mice irradiated at 30 Gy.

CONCLUSION

We present a novel mouse model to study malignant transformation in the context of NF1. Preliminary findings suggest increased malignant transformation at high doses of SI.
TMOD-14. CREATION OF A GENETICALLY ENGINEERED MOUSE MODEL OF ANAPLASTIC ASTROCYTOMA DRIVEN BY THE IDH1-R132H ONCOGENE
Authors: Shi Diana , Wang Adam , Gao Wenhua , Khanal Januka , Levitt Michael , Jennings Rebecca , Bonal Dennis , Signoretti Sabina , Nguyen Quang-De , Cahill Daniel , Abdullah Kalil , Ligon Keith , Kaelin William , McBrayer Samuel
Published: December 2020

Despite the high prevalence of IDH1-R132H mutations in lower grade gliomas, the ability to study this mutation in vivo has been hampered by a lack of faithful mouse models. Therefore, we used a CRISPR/Cas9- and AAV-based strategy to create a genetically engineered mouse model (GEMM) of astrocytoma driven by IDH1-R132H that recreates the genetic landscape of human IDH1 mutant astrocytoma. IDH1 mutations in astrocytomas often co-occur with mutations in TP53, ATRX, and either PIK3R1 or PIK3CA. Using human astrocytes immortalized via expression of telomerase (which phenocopies ATRX loss) and HPV E6 and E7 oncoproteins (which phenocopy p53 and pRb loss, respectively), we found that PIK3R1 and IDH1 oncogenes cooperate to promote anchorage-independent cell growth in vitro and orthotopic brain tumor formation in vivo. These data identified a combination of clinically relevant mutations that we hypothesized could be leveraged to cause spontaneous astrocytoma formation in mice. To simultaneously engineer Idh1, Pik3ca, Tp53, and Atrx mutations in mouse brain tissue, we intracranially injected adeno-associated virus (AAV) expressing Cre recombinase and sgRNAs targeting murine Atrx and Tp53 genes into four mouse strains with the following conditional alleles: 1) LSL-Cas9; 2) LSL-Cas9; LSL-Pik3caH1047R, 3) LSL-Cas9; LSL-Idh1R132H, and 4) LSL-Cas9; LSL-Idh1R132H; LSL-Pik3caH1047R. Grade III anaplastic astrocytomas preferentially formed 9-14 months after injecting the mice carrying both the Idh1 and Pik3ca conditional alleles. These astrocytomas harbored all intended mutations, expressed astrocytoma lineage markers, and displayed elevated (R)-2-hydroxyglutarate, the oncometabolite produced by mutant Idh1. To create an additional model with shorter tumor latency, we transplanted glioma stem-like cells derived from our GEMM into recipient mice to produce Idh1 mutant astrocytoma allografts. These allografts provide a tractable platform for preclinical therapeutic studies. Taken together, our findings show that IDH1 and PI3K oncoproteins cooperate to promote gliomagenesis and unveil new genetically faithful mouse models of mutant IDH1-driven astrocytoma.
TMOD-29. ESTABLISHMENT OF PATIENT-DERIVED XENOGRAFTS FROM RARE PRIMARY BRAIN TUMORS
Authors: Kijima Noriyuki , Nakajima Yoshikazu , Kanematsu Daisuke , Shofuda Tomoko , Higuchi Yuichiro , Suemizu Hiroshi , Mori Kanji , Kodama Yoshinori , Mano Masayuki , Sasaki Atsushi , Inoue Takeshi , Hirato Junko , Kishima Haruhiko , Kanemura Yonehiro
Published: December 2020

Patient derived xenografts are essential tools for translational research and preclinical development of novel therapeutic strategies of primary brain tumors. Recent advances in genomics of primary brain tumors revealed molecular classification of primary brain tumors, thus establishment of patient derived xenografts from each subtype of primary brain tumors is urgently needed. However, currently available patient derived xenografts are limited and are from specific subtype of primary brain tumors such as glioblastoma IDH wild type. In this study, we aim to establish patient derived xenografts from primary brain tumors with various molecular characteristics, especially rare primary brain tumors. We got primary brain tumor tissues from patients, dissociated those tissue into single cells, and orthotopically injected those cells into NOD/Shi-scid IL2Rγ KO mouse. We successfully established rare patient-derived xenografts from atypical teratoid rhabdoid tumor and CNS Ewing sarcoma family tumor with CIC alteration, which is recently described as new entity of primitive neuroectodermal tumors of the CNS. We also analyzed histopathological characteristics of these xenografts and found that each xenograft well recapitulated histopathological features of original patients’ resected tumors. These xenografts have advantages for translational research and preclinical development of novel therapeutic strategies for rare primary brain tumors. In addition, further efforts are needed to establish other types of rare primary brain tumors.
LTBK-01. INO-5401 AND INO-9012 DELIVERED INTRAMUSCULARLY (IM) WITH ELECTROPORATION (EP) IN COMBINATION WITH CEMIPLIMAB (REGN2810) IN NEWLY DIAGNOSED GLIOBLASTOMA
Authors: Reardon David A , Brem Steven , Desai Arati Suvas , Bagley Stephen Joseph , Kurz Sylvia Christine , De La Fuente Macarena Ines , Nagpal Seema , Welch Mary Roberta , Hormigo Adilia , Forsyth Peter , Mandell Jacob , Khagi Simon , Aiken Robert , Walbert Tobias , Lieberman Frank , Portnow Jana , Batiste James , Carroll Nicholas , Sylvester Albert , Campbell Patricia , Lowy Israel , Dolgoter Alex , Boyer Jean , Kraynyak Kimberly , Morrow Matthew P , McMullan Trevor , Weiner David B , Skolnik Jeffrey
Published: December 2020

BACKGROUND

Novel T cell-enabling therapies, in combination with checkpoint inhibition, may improve OS in GBM. INO-5401 (synthetic DNA plasmids encoding hTERT, WT-1, PSMA) plus INO-9012 (synthetic DNA plasmid encoding IL-12), and the PD-1 immune checkpoint inhibitor cemiplimab, is given to patients with newly diagnosed GBM to evaluate tolerability, efficacy and immunogenicity.

METHODS

Phase I/II, single arm, 2 cohort study (A: MGMT unmethylated, B: MGMT methylated). Primary endpoint is safety; efficacy and immunogenicity are secondary. Nine mg INO-5401 plus 1 mg INO-9012 (every 3 weeks x 4 doses, then Q9W) is given IM with EP by CELLECTRA® 2000 with cemiplimab (350 mg IV Q3W). RT is given as 40 Gy over 3 weeks. TMZ is given with radiation (all patients), and adjuvantly (Cohort B only).

RESULTS

Fifty-two subjects enrolled: 32 in Cohort A; 20 in Cohort B. 35% women; median age 60 years (19–78 years). The adverse event profile is consistent with single-agent (INO-5401, INO-9012, EP and cemiplimab) reported events. OS at 12 months was 84.4% (Cohort A) and 85% (Cohort B). OS at 18 months in Cohort A is 50% (95% CI 31.9 - 68.1); median OS is 17.9 months (14.5 - NR); Cohort B OS18 and median OS will be presented. Tumor gene transcripts at diagnosis confirmed expression of INO-5401 antigens. Peripheral immune responses following INO-5401 revealed antigen-specific T cell responses by Interferon gamma ELISpot and flow cytometry, including cytokine production and expansion of antigen specific CD8+T cells with lytic potential.

CONCLUSIONS

INO-5401 + INO-9012, a novel DNA plasmid immunotherapy, demonstrates acceptable risk/benefit and generates robust systemic immune responses to encoded tumor antigens when administered with cemiplimab and RT/TMZ in newly diagnosed GBM patients. Overall survival is encouraging. Clinical trial information: NCT03491683.
ATRT-08. A PHASE II STUDY OF CONTINUOUS LOW DOSE PANOBINOSTAT IN PAEDIATRIC PATIENTS WITH MALIGNANT RHABDOID TUMORS/ATYPICAL TERATOID RHABDOID TUMORS
Authors: Wood Paul , Desai Jayesh , Waldeck Kelly , Cain Jason , Gottardo Nick , Strong Robyn , Kinross Kathryn , Carr Michelle , Jones Janelle , Wong Lily , Ziegler David , Hansford Jordan , Michael Michael , Ashley David
Published: December 2020

BACKGROUND

Panobinostat treatment has been shown to terminally differentiate malignant rhabdoid tumor (MRT)/atypical teratoid rhabdoid tumors (ATRT) in pre-clinical models. This is an open label, phase II study of panobinostat in patients with newly diagnosed or relapsed MRT/ATRT. AIMS: To assess the anti-tumor activity of low dose, continuous panobinostat, its associated toxicities, the biological activity of low dose panobinostat by measuring histone acetylation status in peripheral mononuclear cells (PMNC), and markers of differentiation in fresh tumor tissue specimens.

METHODS

Following cycles of induction and consolidation chemotherapy and/or radiation treatment, patients were enrolled and commenced on panobinostat as a continuous daily oral dose starting at 10mg/m2 following a three-week wash out period between therapies. Real-time acetylation status, measuring acetylated H4 on PMNC, was performed to determine the pharmacodynamics of panobinostat. Patients were monitored for drug toxicities with the possibility of dose reductions in decrements of 2mg/m2.

RESULTS

Six patients with newly diagnosed ATRT/MRT and one patient with relapsed MRT have been enrolled to date. The average age at enrollment was 2.5 years. Currently, six patients (85.7%) remain on study with a mean treatment duration of 170 days (range 44–327 days). One patient was removed from study at day 44 due to disease progression. The main dose-limiting toxicity observed to date has been myelosuppression. Panobinostat, at a dose of 10mg/m2, caused significant acetylation of H4 in PMNC.

CONCLUSIONS

Treatment with panobinostat appears to be well tolerated in infants with MRT/ATRT, with successful real-time pharmacodynamic assessment of H4 acetylation.
ATRT-13. DIFFERENT CELLS OF ORIGIN PAVE THE WAY FOR MOLECULAR HETEROGENEITY IN RHABDOID TUMORS
Authors: Graf Monika , Interlandi Marta , Moreno Natalia , Holdhof Dörthe , Melcher Viktoria , Kastrati Dennis , zu Hörste Gerd Meyer , Dugas Martin , Frühwald Michael C , Albert Thomas K , Schüller Ulrich , Kerl Kornelius
Published: December 2020

Rhabdoid tumors (RT) are rare but highly aggressive pediatric neoplasms. These tumors carry homozygous loss-of-function alterations of SMARCB1 in almost all cases with an otherwise low mutational load. RT arise at different intracranial (ATRT) as well as extracranial (MRT) anatomical sites. Three main molecular subgroups (ATRT-SHH, ATRT-TYR, ATRT-MYC) have been characterized for ATRT which are epigenetically and clinically diverse, while MRT show remarkable similarities with ATRT-MYC distinct from ATRT-SHH and ATRT-TYR. Even though there are hypotheses about various cells of origin among RT subgroups, precursor cells of RT have not yet been identified. Previous studies on the temporal control of SMARCB1 knockout in genetically engineered mouse models have unveiled a tight vulnerable time frame during embryogenesis with regard to the susceptibility of precursor cells to result in RT. In this study, we employed single-cell RNA sequencing to describe the intra- and intertumoral heterogeneity of murine ATRT-SHH and -MYC as well as extracranial MYC tumor cells. We defined subgroup-specific tumor markers for all RT classes but also observed a notable overlap of gene expression patterns in all MYC subgroups. By comparing these single-cell transcriptomes with available single-cell maps of early embryogenesis, we gained first insights into the cellular origin of RT. Finally, unsupervised clustering of published human RT methylation data and healthy control tissues confirmed the existence of different cells of origin for intracranial SHH tumors and MYC tumors independent of their anatomical localizations.
ATRT-15. LY6D – A CANDIDATE FOR NANOPARTICLE-BASED TARGETED THERAPIES OF ATRT
Authors: Hagemeier Lea , Sönksen Marthe , Moreno Natalia , Ettlinger Romy , Bunzen Hana , Kerl Kornelius
Published: December 2020

Atypical Teratoid Rhabdoid Tumors (ATRT) are aggressive brain malignancies of the infant. Despite intensive multimodal therapy, the overall prognosis remains poor, making investigations on targeted therapies crucial. Arsenic trioxide (ATO) is known to inhibit cell growth of ATRT in vitro and in vivo but its efficacy in solid tumors is limited by its adverse effects. We aimed to characterize whether a nanoparticle-based drug delivery could overcome these limitations. Therefore metal-organic frameworks containing ATO (MOF-ATO) were constructed. To improve drug specificity further, we searched for unique proteins on the surface of ATRT, in order to create antibody-drug-conjugates out of MOF-ATO and an ATRT-specific ligand. ATRT are marked by a biallelic loss of SMARCB1, which results in an activation of the repressive histone methyltransferase EZH2. After chemical inhibition of EZH2 with GSK126, a mass spectrometric based screening for differentially expressed surface proteins was performed. Treatment with ATO, as well as MOF-ATO and GSK126 each reduces the cell viability of ATRT cell lines. It results in a cell cycle arrest and an induction in apoptosis, being analysed via MTT test and flow cytometry. GSK126 treatment causes a significant upregulation of several cell surface proteins, upon them the Lymphocyte antigen 6 family member D (LY6D). Being rarely expressed on other human cells, this protein is an interesting candidate. An antibody-drug-conjugate consisting of MOF-ATO and LY6D-ligands could be a promising approach for future targeted therapies of ATRT.
ATRT-21. RHABDOID PREDISPOSITION SYNDROME: REPORT OF MOLECULAR PROFILES AND TREATMENT APPROACH IN THREE CHILDREN WITH SYNCHRONOUS ATYPICAL TERATOID/RHABDOID TUMOR AND MALIGNANT RHABDOID TUMOR
Authors: Shatara Margaret , Gupta Ajay , Arja Mohamed H Abu , Conley Suzanne E , Patel Priyal , Boué Daniel R , Pierson Christopher R , Thomas Diana L , Meyer Erin K , Shah Summit H , Jones Jeremy , Martin Lisa , McAllister Aaron , Schieffer Kathleen M , Varga Elizabeth A , Leraas Kristen , Lichtenberg Tara , LaHaye Stephanie , Miller Katherine E , Magrini Vincent , Wilson Richard K , Cottrell Catherine E , Mardis Elaine R , Aldrink Jennifer H , Auletta Jeffery J , Pindrik Jonathan , Leonard Jeffrey R , Osorio Diana S , Finlay Jonathan L , Ranalli Mark , AbdelBaki Mohamed S
Published: December 2020

BACKGROUND

Rhabdoid predisposition syndrome is characterized by germline alterations in SMARCB1 or SMARCA4, leading to synchronous or metachronous central nervous system (CNS) and extra-CNS rhabdoid tumors. Rare survivors have been reported to date.

METHODS

We describe the molecular profiling and treatment regimen of three patients with synchronous atypical teratoid/rhabdoid tumor (ATRT) and malignant rhabdoid tumor of the kidney (MRT-K). All patients underwent radical nephrectomy of the kidney, and gross total resection of the primary CNS tumor was achieved for two patients. An intensive chemotherapy regimen was administered; an induction phase based on the modified Third Intergroup Rhabdomyosarcoma Study (IRS-III) for ATRT followed by a consolidation phase with three cycles of high-dose chemotherapy and autologous hematopoietic progenitor cell rescue, without irradiation. All three patients were enrolled on an institutional comprehensive genomic profiling protocol.

RESULTS

A germline focal 22q deletion, including SMARCB1, was detected in two patients, while the third patient had a maternally-inherited heterozygous frameshift variant in SMARCB1. Somatic loss of heterozygosity of 22q was identified in all patients, resulting in biallelic inactivation of SMARCB1. Divergent tumor subgroups were described using DNA methylation. The three MRT-K samples were classified as MYC subtype. One ATRT was classified as SHH while the other as TYR. One patient is currently three years off-therapy without evidence of disease, while the other two patients have completed the consolidation phase without recurrent disease.

CONCLUSION

Molecular profiling of CNS and extra-CNS rhabdoid tumors revealed different epigenetic subgroups. An intensive multimodal therapeutic approach without irradiation may achieve prolonged survival.
ATRT-30. RETROSPECTIVE ANALYSIS OF CHILDREN WITH ATYPICAL TERATOID RHABDOID TUMOR TREATED ACCORDING TO ACNS0333
Authors: Hoffman Lindsey , Margol Ashley , Faulk Kelly , Hutchins Sara , Friedman Gregory , Reddy Alyssa , Dhall Girish
Published: December 2020

Atypical teratoid rhabdoid tumor (ATRT) is a central nervous system tumor with poor outcome. ACNS0333, a Children’s Oncology Group phase 3 trial, enrolled 65 evaluable patients who received two cycles of induction chemotherapy, three cycles of consolidative high-dose chemotherapy (HDCT), and focal radiation therapy (RT) pre- or post-consolidation. Craniospinal irradiation (CSI) was left to clinician discretion. We retrospectively analyzed medical records of 27 children treated at our institutions according to ACNS0333. Median age at diagnosis was 14 months (range 4–165); 13 (48%) were male. M-stage was M0, M2, and M3 for 18 (66%), 5 (19%), and 4 (15%), respectively. Tumor location was supratentorial (n=14, 52%), infratentorial (n=12, 44%), or both (n=1, 4%). Complete resection was achieved for 17 (63%). All but one completed induction. Of 13 (51%) with residual disease at diagnosis, 5 (36%) and 7 (50%), respectively, exhibited complete and partial response to induction. Three patients progressed on therapy, and six progressed after completion of therapy at a median of 9.7 months. In all, 18 patients completed RT (16 focal/4 CSI and 6 pre-/12 post-consolidation). Three died of therapy-related toxicity (two in primary therapy and one in relapse therapy), and 8 died of disease. Sixteen patients (59%) are alive at a median follow up of 53 months (range 9–114). Of 17 with germline testing, eight (47%) had rhabdoid predisposition syndrome of whom three are alive. At the time of presentation, data for approximately 50 patients is expected, and we will compare outcomes to soon-to-be published data from ACNS0333.
ATRT-32. GENOME-WIDE CRISPR AND SMALL-MOLECULE SCREENS UNCOVER TARGETABLE DEPENDENCIES IN AT/RTs
Authors: Merk Daniel , Hirsch Sophie , Walter Bianca , Häusser Lara , Persky Nicole , Root David , Schüller Ulrich , Tabatabai Ghazaleh
Published: December 2020

Brain tumors are the leading cause of cancer-related deaths in children and adolescents. Embryonal brain tumors are a group of high-grade neoplasms which primarily affect young patients, and atypical teratoid rhabdoid tumors (AT/RTs) are the second most common type of tumor within this group. In spite of intensive research efforts and the knowledge of molecular mechanisms driving subgroup-specific heterogeneity within ATRTs, survival estimates stay relatively low as compared to other tumor entities with a median survival of around 17 months. More efficacious and durable therapies are urgently needed to improve the situation of patients. We here used a combination of genome-wide CRISPR dependency screens and small-molecule drug assays to identify genetic vulnerabilities and novel therapeutic targets for this tumor entity. Here, we successfully generated a chemical library that shows preferential activity in AT/RT cell lines, thereby validating our CRISPR approach to identify tumor-specific vulnerabilities. Of note, none of the identified dependencies seemed to be subgroup-specific, suggesting that targets identified here can be used as pan-AT/RT therapeutic avenues. Among others, these include inhibition of EGF signaling and CDK4/6. Our data provide a comprehensive map of dependencies for AT/RTs which will serve as a starting point in the development of targeted therapies for this tumor entity.
COVD-02. COVID-19 AND CHILDHOOD CANCER CARE - THEMATIC ANALYSIS OF PUBLISHED SCIENTIFIC AND CLINICAL LITERATURE
Authors: Barton Chris
Published: December 2020

INTRODUCTION

The SARS-CoV-2 pandemic has affected modern medicine and healthcare provision profoundly. National and regional experiences with COVID-19 have been hugely variable across the globe, reflecting ethnic, governmental, cultural, economic and healthcare differences. This thematic analysis was performed to identify scientific and clinical literature relating to the impact of COVID-19 on children with cancer and treatment.

METHODS

The NHS Evidence portal was used to conduct a healthcare database advanced literature search. Duplicates were removed. Remaining results were screened using clear inclusion and exclusion criteria.

RESULTS

172 results were identified and data extracted. Literature was identified from all 5 continents, with lower and middle income countries well represented. Key themes identified included: 1: Impact on patients already diagnosed, including decreased treatment regimens, impact on outpatient clinics, COVID susceptibility and travel restrictions; 2: Delays in presentation and diagnosis, and national screening programs; 3: The impact of COVID on healthcare professionals; 4: Impact on current and future research; 5: Consequence of global economic crisis on childhood cancer care; 6: Impact on long-term survivorship, late effects and surveillance monitoring.

CONCLUSION

COVID-19 has had a profound effect on health care, and the literature reflects the extent to which communities involved in childhood cancer care have worked together to minimise the impact. It is inevitable that there have been consequences of the pandemic on the treatment of existing patients, and the diagnosis of new ones, but evidence suggest these effects in the short term are minimal. The greatest concerns are for immediate and short-term research conduct.
COVD-03. IMPACT OF COVID-19 ON THERAPY PROVISION FOR CHILDREN WITH CNS TUMOURS
Authors: Hartley Helen , Pizer Barry , Kumar Ram , Owen Joanne , Paisley Helen , White Amillie
Published: December 2020

INTRODUCTION

The COVID-19 pandemic has led to widespread change in the delivery of rehabilitation. The Teenage Cancer Trust reported that 69% of young people with cancer saw their physiotherapist less than usual during the pandemic raising concerns about physiotherapy input.

METHODS

Retrospective analysis of all children’s therapy input managed under the Neuro Oncology Rehabilitation Team (NORT) between 1st April and 30th July 2020. Descriptive analysis of change to physiotherapy provision during this time period by Tertiary and local community services.

RESULTS

49 children were managed under the NORT Therapy Team during this timeframe. 9 children were newly diagnosed with CNS tumours. There was no impact on inpatient therapy provision, 3 had delayed local therapy provision on discharge requiring increased virtual input by the Tertiary centre. 40 children were outpatients managed under the NORT therapy team. 16 children were also receiving regular local physiotherapy input prior to the COVID-19 pandemic. 13 of these children subsequently had their local physiotherapy input suspended during this time period, 8 children were offered virtual input as an alternative by the Tertiary centre, 2 children received increased face to face appointments at the Tertiary centre. 14 of the 24 children managed solely under the Tertiary NORT Therapy Team changed to virtual therapy reviews.

DISCUSSION

There is a clear change in therapy provision as a result of the COVID-19 pandemic. Future research should consider the effectiveness of neurorehabilitation conducted virtually and the impact on physical function of reduced local therapy provision in children with CNS tumours.
DDEL-04. ENGINEERED NANOCARRIERS TO ENHANCE DRUG DELIVERY ACROSS THE BLOOD-BRAIN BARRIER
Authors: Straehla Joelle P , Hajal Cynthia , Safford Hannah , Offeddu Giovanni , Wyckoff Jeffrey , Kamm Roger D , Hammond Paula T
Published: December 2020

Pediatric central nervous system tumors are the leading cause of cancer death in children. Promising therapeutics have been identified, but the ability to deliver an effective concentration to the tumor without causing excessive systemic toxicity remains a challenge. To address this, we leveraged a tunable nanocarrier platform to design a brain-penetrant nanocarrier with preferential uptake into tumor cells over healthy brain cells. First, we used the layer-by-layer technique to iteratively coat liposomes with nanometers-thick layers of oppositely charged polyelectrolytes. To investigate the influence of surface chemistry on cellular trafficking, a panel of layered liposomes was tested for interactions with cancer cell lines, identifying poly-L-aspartic acid and hyaluronic acid as the highest-performing formulations across brain tumor lines. To facilitate nanocarrier transit across the blood-brain barrier (BBB), we developed a click chemistry platform to functionalize the nanocarrier with BBB shuttle ligands. To investigate trafficking in vitro, we utilized a microfluidic brain microvascular model comprising endothelial cells, astrocytes, pericytes, and glioma cells that self-assemble into a perfusable vascular network. We found that nanocarrier size influenced vascular transport, and the addition of BBB shuttle ligands improved transport in the presence of a glioma spheroid. To investigate in vivo nanocarrier trafficking, we performed intravital imaging through a cranial window in anesthetized mice. After intravenous administration, nanocarrier transit across intact brain capillaries was visualized using two photon microscopy, and vessel permeability was quantified over time. Ongoing studies in mice bearing patient-derived xenograft medulloblastoma and glioma tumors are being conducted to further characterize trafficking across tumor-associated vasculature.