bluuebunny/crossref_metadata_2025 huggingface dataset:
CTNI-68. EFFICACY OF TTFIELDS IN ELDERLY PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA (GBM) – SUB-GROUP ANALYSIS OF THE EF-14 TRIAL
Authors: Ram Zvi , Kim Chae-Yong , Zhu Jay-Jiguang
Published: December 2020

BACKGROUND

Tumor Treating Fields (TTFields) are an anti-mitotic, regional treatment that utilizes low intensity alternating electric fields delivered non-invasively to the tumor using a portable medical device. In the EF-14 phase 3 study leading to FDA approval, TTFields significantly extended survival in newly diagnosed GBM when added to maintenance temozolomide (TMZ). Elderly GBM patients usually have worse prognosis and often receive only partial treatment for the disease. This sub-group analysis examined the effects of TTFields in the elderly population (≥65 years of age) enrolled in the EF-14 study.

METHODS

All 134 elderly patients (≥65 years of age) from the EF-14’s intent-to-treat population were included in the analysis, Overall survival (OS) and progression-free survival (PFS), as well as adverse event frequency and severity were compared between the TMZ/TTFields arm and the TMZ alone arm.

RESULTS

The median age was 69 (range: 65–83), median KPS was 90%, and 69% were male. Median PFS from randomization was 6.5 months versus 3.9 months in the TMZ/TTFields versus TMZ alone arms, respectively (hazard ratio [HR], 0.47 [95%CI 0.30, 0.74] P< 0.0236). Median OS was 17.4 months versus 13.7 months in the TMZ/TTFields versus TMZ alone arm, respectively (HR 0.51 [CI 0.33, 0.77] P< 0.020). Serious adverse events (SAEs) were reported in 39% of patients treated with TMZ/TTFields and in 33% of patients treated with TMZ alone. None of the SAEs were considered related to TTFields but attributed to TMZ or to the underlying disease. Grades 1–2 skin AEs related to TTFields were observed in 51% of patients.

CONCLUSION

Consistent with the overall outcome of the EF-14 study, elderly patients treated with TMZ/TTFields showed significantly better OS compared to patients on TMZ alone, and without increase in grade III or IV toxicity.
CTNI-69. PRECISION NEURO-ONCOLOGY TREATMENT GUIDED BY NEXT GENERATION SEQUENCING (NGS)-BASED COMPREHENSIVE GENOMIC PROFILING: REAL WORLD EXPERIENCE IN HONG KONG
Authors: Lam Tai-Chung , Chen Shu Jen , Tan Kien Thiam , Li Lai Fung , Pu Jenny K S
Published: December 2020

BACKGROUND

The development of next generation sequencing (NGS) based comprehensive genomic profiling (CGP) has enabled identification of druggable somatic mutations in brain tumours. This cohort reviewed the efficacy of CGP-guided precision treatment in a tertiary neuro-oncology centre.

METHODOLOGY

From May 2017 to May 2020, CGP were arranged for 43 patients. All patients had exhausted conventional treatments or received CGP for clinical trial screening. Targeted deep NGS was used to assess the mutational status, single nucleotide variant, small insertions and deletions and copy number variant of 440 cancer-related genes.

RESULTS

The diagnoses of the 43 patients were GBM (n=23), high grade glioma (n=11), brain metastases (n=4), chordoma (n=3), atypical choroid plexus papilloma (n=1) and meningioma (n=1). In most of the patients (42/43, 97.7%), CGP identified at least one druggable targets with a median of 3. Based on the CGP, 27 patients received precision treatment (62.7%). Among these, 14 were GBM and 6 were other high grade glioma. Treatment given included PARP inhibitors, immunotherapy, multi-kinase inhibitor, selective CDK4/6 inhibitor and mTOR inhibitor. Clinical benefit was achieved in 20 patients out of 27 (74%), including 2 complete response (7.4%), 9 partial response (33.3%) and 9 stable disease (33.3%). The median progression free survival (PFS) were 183 days [95% confident intervals (CI): 81–302 days]. For GBM/high grade glioma patients, median PFS was 125 days [95% CI: 52–215] and six-month PFS was 32.7%. Treatment toxicity was mild except two patients developed grade 3 complications and one grade 5 complication (fatal neutropenic fever). For the 16 patients who did not receive precision treatment, one had no druggable target identified, nine were still stable on standard therapies, 6 were too weak when CGP was available.

CONCLUSION

CGP guided precision treatment for selected, advanced neuro-oncological patients yielded modest clinical efficacy and satisfactory safety profile in real world setting.
CTNI-74. PHASE 3 TRIDENT TRIAL: CONCOMITANT RADIATION THERAPY (RT) AND TEMOZOLOMIDE +/- TUMOR TREATING FIELDS (TTFIELDS) IN NEWLY DIAGNOSED GLIOBLASTOMA
Authors: Shi Wenyin , Kleinberg Lawrence , Jeyapalan Suriya A , Goldlust Samuel , Nagpal Seema , Combs Stephanie E , Roberge David , Nishigawa Ryo , Grossman Rachel , Glas Martin
Published: December 2020

BACKGROUND

Tumor treating fields (TTFields) is a non-invasive, regional antimitotic treatment approved as a standard-of-care for newly diagnosed glioblastoma (ndGBM). In the EF-14 Phase 3 trial, TTFields (200 kHz) plus temozolomide (TMZ) significantly increased survival of ndGBM patients without increasing systemic toxicity. TTFields-related AEs were mainly skin AEs. In preclinical models, TTFields increase the therapeutic effects of radiation therapy (RT). A pilot study showed that TTFields concomitant with RT and TMZ is well tolerated. The benefit of concomitant TTFields with RT and TMZ will be tested in the TRIDENT trial.

METHODS

TRIDENT is an international phase III randomized trial comparing standard RT with TMZ vs the triple combination of RT/TMZ with concomitant TTFields. RT is delivered through the TTFields arrays. Patients in both arms will receive maintenance TTFields/TMZ. TTFields (200 KHz) will be delivered >18 hours/day using Optune. Patients will continue TTFields treatment until second recurrence. Patients with pathologically confirmed ndGBM, ≥ 18 years, KPS ≥ 70, either sex, post-surgery or biopsy, and amenable for RT/TMZ therapy will be stratified by extent of resection and MGMT promoter methylation status. The primary endpoint is overall survival (OS). Secondary end points: progression free survival (PFS; RANO), 1- and 2-year survival rates, overall radiological response (ORR; RANO), progression-free survival (PFS6M, PF12M, PFS2Y); severity and frequency of AEs (CTCAE V5.0); pathological changes in resected GBM tumors post treatment; quality of life (EORTC QLQ-C30); and correlation of OS to TTFields compliance. The hypothesis is that concomitant TTFields/RT/TMZ will significantly improve OS versus RT/TMZ. Sample size (N=950; 475/arm) will detect a HR< 0.8 with 5% type I error. Survival will be measured from the time of randomization until date of death. At the time of analysis, patients lost to follow-up or still on protocol follow-up will be censored at the last date known to be alive.
CTNI-75. A PILOT CLINICAL TRIAL OF OROTECAN (VAL-413), A NOVEL ORAL DOSAGE FORMULATION OF IRINOTECAN: IMPLICATIONS FOR PEDIATRIC BRAIN TUMORS
Authors: Brown Dennis , Bacha Jeffrey , Wagner Lars , Leggas Markos , Kanekal Sarath , Lopez Lorena , Sankar Neil
Published: December 2020

Tumors of the brain and of the central nervous system (CNS) are the most common solid tumors in children. Intravenous irinotecan hydrochloride (IRN-IV) is approved for the treatment of adult colorectal cancer. IRN-IV is also used off-label in a wide range of treatment regimens for recurrent adult and pediatric tumors including glioblastoma, pediatric glioma and medulloblastoma. Recently, commercially available IRN-IV has been administered orally (IRN-IVPO) in pediatric patients to reduce intravenous administration-related side effects, improve convenience and reduce clinic time and costs. Unfortunately, the poor palatability of this preparation leads to poor compliance, especially in pediatric patients. VAL-413 is novel formulation developed to improve tolerability of oral irinotecan. The current study (NCT04337177) evaluates the safety and pharmacokinetics of VAL-413 administered with temozolomide for treatment of recurrent pediatric solid tumors. METHODS: Up to 20 patients ≥ 1 to ≤ 30 years of age with recurrent pediatric solid tumors will be enrolled. The primary objective is to establish the recommended phase II dose of VAL-413 when given in combination with temozolomide. Secondary objectives include characterization of the pharmacokinetics of VAL-413 vs. IRN-IVPO, evaluating palatability of VAL-413, assessing the toxicity profile of VAL-413 in combination with temozolomide, and assessment of tumor response. Toxicity is evaluated based on CTCAEv5 and tumor response based on RECISTv1.1. An update on the progress of this trial will be presented.
CTNI-76. PHASE 2 CLINICAL TRIAL OF VAL-083 IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GBM
Authors: Chen Zhong-ping , Guo Cheng-Cheng , Yang Qun-ying , Wu Shao-xiong , Li Jia-Wei , Bacha Jeffrey , Johnson Greg , Langlands John , Schwartz Richard , Kwan Claire , Kanekal Sarath , Steino Anne , Lopez Lorena , Brown Dennis
Published: December 2020

Approximately 60% of glioblastoma multiforme (GBM) patients possess an unmethylated methylguanine DNA-methyltransferase (MGMT) promoter region, which confers a limited response to standard-of-care treatment with temozolomide (TMZ), resulting in shorter median survival when compared to patients with methylated MGMT promoter. VAL-083 is a novel bi-functional DNA targeting agent that induces inter-strand cross-links at N7-guanine, leading to DNA double-strand breaks and ultimately cell death. VAL-083 circumvents MGMT-mediated TMZ resistance in vitro and in vivo. A Phase 2 study has been initiated for VAL-083 in newly diagnosed MGMT unmethylated GBM. The study has 2 stages: Stage 1 is a dose-escalation safety and tolerability phase to confirm the phase 2 dose of VAL-083 when administered concurrently with radiation therapy (RT). Patients received VAL-083 at 20, 30, or 40 mg/m2/day x 3 days every 21 days along with standard radiation treatment (RT) (2 Gy/day, 5 days/week). The dose escalation stage is complete, and 30 mg/m2/day of VAL-083 in combination with RT was generally safe and well-tolerated. Stage 2 comprises an expansion phase to enroll up to 20 additional patients at the 30 mg/m2/day of VAL-083 in combination with RT. As of June 2, 2020, all patients have been enrolled, with a total of 29 patients in the study, and 25 patients receiving 30 mg/m2/day VAL-083. Of the 29 patients enrolled, 27 have completed their prospectively planned MRI scans and had their initial assessment for tumor response. Two additional patients died prior to their post-cycle 3 MRI. Consistent with our prior experience, myelosuppression was the most common adverse event. Three patients have experienced dose-limiting toxicities - one (1/3; 33%) at the 40 mg/m2/day and two (2/25; 8%) at the 30 mg/m2/day dose. Further safety and efficacy updates will be presented at the meeting. Clinicaltrials.gov identifier: NCT03050736.
CTNI-77. EF-19, A POST-APPROVAL REGISTRY STUDY OF TUMOR TREATING FIELDS (TTFIELDS) IN RECURRENT GLIOBLASTOMA (rGBM)
Authors: Zhu Jay-Jiguang , O’Donnell Robert T , Goldlust Samuel , Ram Zvi
Published: December 2020

BACKGROUND

Tumor Treating Fields (TTFields) are an anti-mitotic therapy of alternating electric fields delivered non-invasively to the tumor. In phase 3 studies leading to FDA-approvals, TTFields plus temozolomide (TMZ) significantly extended survival in newly diagnosed GBM, and achieved comparable survival to best standard of care (BSC) as monotherapy in recurrent GBM (rGBM). The EF-19 study evaluated efficacy of TTFields vs BSC in rGBM in post-approval real-life setting.

METHODS

This registry trial (192 rGBM patients, >21 yrs, KPS > 70) were treated with TTFields (200 kHz, >18h/day). Primary endpoint was overall survival (OS); secondary endpoints were OS in the per protocol (PP) population, time to treatment failure and adverse events (AEs). The registry data were compared to OS of all 117 patients in EF-11 BSC group (Stupp EJC 2012). The sample size (N=192) was based on non-inferiority log-rank test with two-sided alpha (0.05), 80% power, HR of 1.0 comparing TTFields to control with an upper one-sided 95% CI of HR < 1.375.

RESULTS

Median OS with TTFields versus EF-11 BSC was 7.4 versus 6.4 months, p=0.053; HR = 0.64 (95%CI 0.46–0.91, Cox-test P=0.012). Median OS (PP) with TTFields versus EF-11 BSC was 8.1 months versus 6.5 months; p=0.045; HR 0.65. OS was significantly higher TTFields as the 95% CI upper limit of HR was lower than the pre-defined threshold of 1.375. The overall incidence of AEs was lower with TTFields than EF-11 BSC (67% vs. 95%). The median time to treatment failure was longer in the TTFields arm (3.3 months (95% CI 2.6, 3.9) versus BSC arm (1.6 months; 95% CI 1.1, 1.9); HR=0.53 (95% CI 0.41, 0.68, p< 0.0001). Skin AE was the most common AE in the TTFields arm.

CONCLUSION

The results of the EF-19 registry study confirm the effectiveness and safety of TTFields monotherapy in rGBM.
CTNI-78. A PEDIATRIC AND YOUNG ADULT PHASE I DOSE ESCALATION SAFETY STUDY OF BXQ-350 FOR REFRACTORY SOLID AND CENTRAL NERVOUS SYSTEM TUMORS
Authors: Setty Bhuvana , AbdelBaki Mohamed , DeWire Mariko , Cripe Timothy , Curry Rich
Published: December 2020

BACKGROUND

BXQ-350 is a novel agent composed of the multifunctional, lysosomal activator protein Saposin C (SapC) and dioleoyl- phosphatidylserine (DOPS) and has demonstrated antitumor effects in both in vitro and in vivo preclinical models. Many tumors, including high-grade glioma and diffuse intrinsic pontine glioma (DIPG), and cells of tumor vasculature have aberrantly-exposed phosphatidylserine (PS)-rich domains on the cell surface. BXQ-350 is an anti-tumor agent in development from Bexion Pharmaceuticals, Inc. that selectively targets tumor cell PS, particularly those translocated to the outer leaflet of the plasma membrane in tumor cells. BXQ-350 activates and participates in various cellular processes, including apoptosis and necrosis, and may also exhibit novel mechanisms leading to cell death that require further investigation.

METHODS

Nine refractory solid (2) and central nervous system (7) tumor patients (5F:4M, age 4–23 years of age) were enrolled in a 2-site dose escalation Phase I first-in-pediatric trial (NCT03967093) which completed in 2019. All patients received at least one dose of BXQ-350 which was administered as an intravenous infusion. Dosing began at 1.8 mg/kg and escalated to the highest planned dose level of 3.2mg/kg.

RESULTS

There were no BXQ-350-related serious adverse events, dose limiting toxicities or withdrawals. The highest planned dose of 3.2 mg/kg was achieved safely but a maximum tolerated dose was not established. One osteosarcoma patient had progressive disease prior to completing cycle one of treatment and was removed from trial. Eight patients (DIPG-3, HGG-1, GBM-1, Pineoblasotoma-1, Ependymoma-1, Osteosarcoma-1) completed at least one cycle, with one DIPG patient completing cycle five.

CONCLUSION

BXQ-350 was well tolerated with no significant dose-limiting toxicities at the highest planed dose level. A pediatric Phase I trial in newly diagnosed patients is planned for 3rd quarter 2020.
CTNI-79. PRICOTTF TRIAL: A PHASE I/II TRIAL OF TTFIELDS PRIOR AND CONCOMITANT TO RADIOTHERAPY IN NEWLY DIAGNOSED GLIOBLASTOMA
Authors: Kebir Sied , Lazaridis Lazaros , Schmidt Teresa , Oster Christoph , Pierscianek Daniela , Guberina Nika , Kleinschnitz Christoph , Proescholdt Martin , Hau Peter , Grosu Anca-Ligia , Sure Ulrich , Scheffler Björn , Stuschke Martin , Glas Martin
Published: December 2020

OBJECTIVE

Survival rates were significantly improved when adding TTFields to adjuvant chemotherapy with temozolomide in patients with newly diagnosed glioblastoma (nGBM) in the phase 3 EF-14 trial. TTFields therapy is applied at 200 kHz by arrays that are placed at the patients’ scalp. In preclinical studies, the combination of TTFields and radiotherapy demonstrated synergistically enhanced efficacy in GBM cells. Here, we present the PriCoTTF trial, which is currently enrolling nGBM patients and will assess the safety and efficacy of TTFields initiated prior and concomitant to radiochemotherapy.

METHODS

After surgery and complete wound-healing, TTFields therapy will be initiated in newly diagnosed GBM patients. TTFields therapy will continue throughout radiochemotherapy and adjuvant chemotherapy for a total of approximately 9 months. Radiotherapy will be conducted through the arrays, by which TTFields therapy is delivered. Totally, thirty-three patients will be enrolled in two arms. In arm A, 20 adult patients will be enrolled to receive normo-fractionated radiotherapy and in arm B, 13 elderly patients will be treated by hypo-fractionated radiotherapy. The patients will receive chemotherapy according to institutional standard and interdisciplinary tumor conference.

RESULTS

Safety and tolerance based on the frequency of pre-specified treatment-limiting toxicities is defined as primary endpoint of the trial. Secondary endpoints include the frequency of adverse events, progression-free survival (PFS), and overall survival (OS). The trial is currently enrolling patients at four sites in Germany. To date, 13 patients were included (May 2020). Initial practical experiences will be presented.

CONCLUSION

The combination of TTFields and radiotherapy is an encouraging approach to further improve survival of GBM patients. In the presented phase I/II trial, the safety and efficacy of TTFields initiated prior and concomitant to RT in newly diagnosed GBM will be assessed. In addition, initial efficacy data (phase II) can serve as a rationale for a randomized phase III trial.
DDRE-07. DIPG HARBOUR ALTERATIONS TARGETABLE BY MEK INHIBITORS, WITH ACQUIRED RESISTANCE MECHANISMS OVERCOME BY COMBINATORIAL INHIBITION
Authors: Izquierdo Elisa , Carvalho Diana , Mackay Alan , Temelso Sara , Boult Jessica K R , Molinari Valeria , Stubbs Mark , Grabovska Yura , Yu Lu , Choudhary Jyoti , Depani Sarita , o’Hare Patricia , Robinson Simon P , Hubank Michael , Hargrave Darren , Jones Chris
Published: December 2020

The survival of children with diffuse intrinsic pontine glioma (DIPG) remains dismal, with new treatments desperately needed. In the era of precision medicine, targeted therapies represent an exciting treatment opportunity, yet resistance can rapidly emerge, playing an important role in treatment failure. In a prospective biopsy-stratified clinical trial, we combined detailed molecular profiling (methylation BeadArray, exome, RNAseq, phospho-proteomics) linked to drug screening in newly-established patient-derived models of DIPG in vitro and in vivo. We identified a high degree of in vitro sensitivity to the MEK inhibitor trametinib (GI50 16-50nM) in samples, which harboured genetic alterations targeting the MAPK pathway, including the non-canonical BRAF_G469V mutation, and those affecting PIK3R1 and NF1. However, treatment of PDX models and of a patient with trametinib at relapse failed to elicit a significant response. We generated trametinib-resistant clones (62-188-fold, GI50 2.4–5.2µM) in the BRAF_G469V model through continuous drug exposure, and identified acquired mutations in MEK1/2 (MEK1_K57N, MEK1_I141S and MEK2_I115N) with sustained pathway up-regulation. These cells showed the hallmarks of mesenchymal transition, and expression signatures overlapping with inherently trametinib-insensitive primary patient-derived cells that predicted an observed sensitivity to dasatinib. Combinations of trametinib with dasatinib and the downstream ERK inhibitor ulixertinib showed highly synergistic effects in vitro. These data highlight the MAPK pathway as a therapeutic target in DIPG, and show the importance of parallel resistance modelling and rational combinatorial treatments likely to be required for meaningful clinical translation.
DDRE-14. HEMP DERIVED EXTRACELLULAR VESICLES (EVS): A POTENTIAL ANTI-GLIOMA THERAPY
Authors: Azari Hassan , Koopaei Nasser Nassiri , Nouri Mohammad-Zaman , Hall Jesse D , Denslow Nancy D , Schmittgen Thomas D , Reynolds Brent A
Published: December 2020

INTRODUCTION

Extracellular vesicles (EVs) have been harvested from many plant sources, some of which have anti-cancer effects and some could be used as therapeutic nanodelivery vectors. Hemp plant is a natural source of cannabinoids, of which delta 9-tetrahydroxicannabinol (THC) and cannabidiol (CBD) have proven anti-cancer proprieties.

HYPOTHESIS

We hypothesized that hemp EVs are enriched in cannabinoids and their application will reduce glioblastoma (GBM) tumor progression.

APPROACH

EVs were isolated from the hemp plant using ultracentrifugation. Nanotracking analysis, electron microscopy and liquid chromatography tandem mass spectrometry (LC-MS/MS) were utilized to characterize EVs. GBM cell lines were cultured in the neuropshere assay to evaluate hemp EVs anti-glioma effects. Fluorescent-labelled EVs were used to evaluate their brain tissue distribution in orthotopic patient-derived GBM xenografts.

RESULTS

Hemp EVs have a median diameter of 112.6nm with a typical lipid-bilayer structure. LC-MS/MS have shown that while cannabidiolic, cannabigerolic, and tetrahydroxicannabinolic acids represent 69.1 ± 2.1%, 19.1 ± 1.6%, 6.5 ± 0.54% of the total cannabinoids in hemp EVs, CBD and THC only make 4.75 ± 0.26%, and 0.5 ± 0.3%. Hemp EVs are potent anti-glioma agents with a 7-day LD-50 of 1.04µM and 2.4µM [based on EVs total cannabinoid content] for KR-158 and L0 GBM lines, respectively. Compared to the vehicle, overnight incubation of L0 cells with 1µM hemp EVs significantly reduced GBM cell migration (630.3 ± 61.43 vs 143.7 ± 8.7). Intranasal administration of hemp EVs led to a widespread distribution in tumor bearing brain including GBM tumor core.

CONCLUSION

Based on these results, hemp EVs with enriched cannabinoid content exert antiglioma effect in-vitro and when delivered intranasally, are widely distributed throughout the brain and within the tumor of PDX animals. Further experiments are ongoing to address the impact of nasally-delivered hemp EVs on tumor progression and compare to the application of purified acidic cannabinoids.
DDRE-30. HIGH-THROUGHPUT DRUG SCREENING OF FDA-APPROVED ANTINEOPLASTIC DRUGS FOR THE TREATMENT OF AGGRESSIVE MENINGIOMAS
Authors: Jungwirth Gerhard , Yu Tao , Liu Fang , Warta Rolf , Unterberg Andreas , Herold-Mende Christel
Published: December 2020

The management of aggressive meningiomas remains challenging due to limited treatment options besides surgical removal and radiotherapy. High recurrence rates and lack of effective chemotherapies may be reasons for the unfavorable prognosis of these patients. Consequently, there is an urgent need to identify effective therapeutic agents. For this purpose, we performed a high-throughput screening utilizing a drug library consisting of 147 FDA-approved antineoplastic drugs on the anaplastic meningioma cell line NCH93 using CellTiter-Glo (Promega). Based on the lowest IC50, the top 5 drugs were selected including Bortezomib, Carfilzomib, Omacetaxine, Ixabepilone, and Romidepsin. Validation of candidate compounds was performed in Ben-Men-1 (grade I), NCH93 (grade III), and IOMM-Lee cells (grade III) using crystal violet assay. Dose-curve analysis revealed IC50 values in the lower nanomolar range for all compounds and all cell lines (0.2 – 16.2 nM). To further substantiate our findings, cell proliferation assessed by manual counting was significantly reduced by up to 90% by each candidate drug at 10xIC50 after 48 h (P < 0.001). Furthermore, cell migration was inhibited up to 60% by all candidate drugs at the respective IC50 (P < 0.05). However, colony formation was only significantly reduced by Bortezomib and Carfilzomib (P < 0.001). The impact of the drugs on cell cycle and apoptosis was analyzed by flow cytometry using Annexin V/PI staining. All candidate drugs induced cell cycle arrest at G0/G1 or G2/M phase (P < 0.001) and subsequently induced apoptosis. Among them, Bortezomib exhibited the most pronounced effect by up to 80% of apoptotic cells (P < 0.001). In summary, by utilizing a high-throughput drug screening we were able to identify Bortezomib, Carfilzomib, Omacetaxine, Ixabepilone, and Romidepsin as potent antineoplastic agents for the treatment of aggressive meningiomas.
DDRE-31. EVALUATION OF HIGHLY POTENT AND SELECTIVE SINGLE-MOLECULE DUAL EGFR/PI3K INHIBITORS IN ADULT AND PEDIATRIC HIGH-GRADE GLIOMA
Authors: Gangadharan Achintyan , Sun Yusha , Bailey Cavan , Carter Trever , Espejo Alexsandra , Whitehead Christopher , Leopold Judith , Chandra Joya
Published: December 2020

High grade gliomas (HGG) carry poor prognosis with median survival rates under 15 months post diagnosis. Due to dysregulation of kinase signaling pathways within these tumors, targeted kinase inhibition has been considered as a promising clinical strategy. However in HGG, many single-agent inhibitors of EGFR or PI3K have shown limited response due to activation of compensatory signaling. Single-molecule multikinase inhibitors may decrease resistance, present a single pharmacokinetic dosage profile, and reduce risks of multi-agent toxicities, supporting this strategy over dual drug combination approaches. To test this concept, a panel of inhibitors exploiting known binding modes of structurally-related ATP binding site inhibitors of EGFR/PI3K were synthesized and characterized. Of these, MTX-241 was least likely to act as a substrate for drug efflux proteins such as P-glycoprotein. Treatment of MTX-241 in a panel of eight human adult and pediatric HGG lines showed strong cytotoxic potency measured by growth inhibitory activity, with IC50s in the < 10 µM range. Tumor selectivity of MTX-241 was observed, with normal human astrocytes (NHA) nearly insensitive to MTX-241 even at >100 µM. MTX-241 was significantly more potent than clinically relevant inhibitors targeting EGFR/RTKs (gefitinib, lapatinib, dasatinib, imatinib) or PI3K (alpelisib, idelalisib). Synthesis and evaluation of a new series of compounds based on MTX-241 structure, but optimized for improved stability is ongoing. Our data suggests that a dual inhibitor of EGFR and PI3K, represents a viable therapeutic strategy in adult and pediatric HGG. Future studies will focus on evaluation of in vivo efficacy in tumor bearing mouse models.
EPCO-02. MOLECULAR CHARACTERIZATION OF TWO NOVEL MPNST SUBGROUPS IDENTIFIES THERAPEUTIC OPPORTUNITIES
Authors: Suppiah Suganth , Mansouri Sheila , Mamatjan Yasin , Liu Jeff , Patil Vikas , Bhunia Minu , Mehani Bharati , Suppiah Ying , Karimi Shirin , Singh Olivia , Aldape Kenneth , Largaespada David , Zadeh Gelareh
Published: December 2020

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive Schwann-cell derived sarcomas. These tumors are resistant to all current therapies, with exception to gross total surgical resection, and unresectable or metastatic tumors are considered incurable. Our understanding of the molecular alterations driving malignant transformation is limited, and to date, targeted therapies have proven ineffective. In this study, we leverage multi-platform genomic and epigenomic profiling of human MPNSTs and neurofibromas to identify targetable molecular pathways that lead to malignant transformation. Unsupervised consensus hierarchical clustering of the top 20K most variable methylated probes yielded seven stable and robust subgroups that are clinically relevant. The high-grade MPNSTs formed two distinct methylation-based clusters (MPNST-G1 and MPNST-G2). MPNST-G1 had worse prognosis compared to MPNST-G2 (0.6 years versus 1.4 years, p < 0.05). PTCH1 loss or SMO gain was prevalent in MPNST-G1 compared to MPNST-G2 (75% vs 12.5%, p < 0.05). In addition, MPNST-G1 harbored PTCH1 CpG island promoter hypermethylation in (87.5% vs 12.5%, p < 0.001). Transcriptome profiling recapitulated the two distinct MPNST subgroups. We next demonstrated that that RB1 signaling pathways are aberrant in both MPNST-G1 and MPNST-G2. However, SHH pathway activation is observed in MPNST-G1, while WNT/CCND1/ ß-catenin pathway activation is observed in MPNST-G2. Network-based drug-disease proximity analysis identified SMO inhibitors as a potential FDA approved drug as a potential targeted therapy. To determine if SHH pathway activation is sufficient for malignant transformation, we knocked out PTCH1 in immortalized neurofibroma cells lines. In 3 different cell lines with PTCH1 knockout, we observed induction of a malignant phenotype, with increased cellular proliferation and invasion. Most importantly, in-vitro and in-vivo models confirm that targeting the SHH pathway, with sonidegib, was effective in inhibiting tumor growth proving SMO inhibition to be a novel therapeutic option in these lethal cancers.
EPCO-03. REPORT OF NTRK FUSION IN A PEDIATRIC PATIENT WITH SPINAL GANGLIOCYTOMA
Authors: Gupte Avanti , Toll Stephanie , Marupudi Neena , Gorsi Hamza
Published: December 2020

BACKGROUND

Gangliocytomas are rare WHO grade 1 central nervous system tumors of neuronal/ mixed neuronal-glial classification that most commonly occur in the cerebrum, favoring the temporal lobe. They are also reported in cerebellum in the setting of Lhermite-Duclos disease. Spinal gangliocytomas are exceedingly rare, constituting 3–10% of reported pediatric cases. Maximal safe surgical resection is the mainstay of therapy, as response to irradiation or traditional chemotherapy is variable. Given the rarity of these tumors, little is known about the molecular makeup or the role of targeted therapy in this population.

CASE

Our patient presented as a 7-year-old male with thorocolumbar scoliosis. A magnetic resonance imaging (MRI) of his spine incidentally demonstrated a heterogeneously enhancing, expansile solid and cystic intramedullary thoracic mass from T6 through T11. MRI brain did not show any intracranial mass. He subsequently underwent a laminectomy with laminoplasty for the intramedullary mass. Histopathologic analysis confirmed a WHO grade I gangliocytoma with moderately cellular abnormal central neural tissue composed of irregular clusters and cords of mature-appearing neurons in a coarse neuropil background. Because of the unusual location and presentation of his disease, molecular analysis including DNA and RNA sequencing was performed which revealed a somatic BCR-NTRK2 fusion.

DISCUSSION

NTRK gene fusions are known oncogenic drivers, reported with varying frequency in many pediatric and adult tumors. They are reported in < 1% of adult head and neck cancers but greater than 90% of congenital infantile fibrosarcomas. NTRK fusions are seen in pediatric brain tumors like infantile high grade gliomas, however they have not been previously reported in gangliocytoma. As TRK inhibitors are efficacious in treating a number of NTRK-rearranged malignancies, this novel finding provides a therapeutic option for NTRK fusion positive gangliocytoma where complete surgical resection is not safely possible.
EPCO-05. LOSS OF THE H4 LYSINE METHYLTRANSFERASE KMT5B DRIVES INVASION / MIGRATION BY DEPLETING H3K27me3 AT LOCI OTHERWISE RETAINED IN H3K27M MUTANT DIPG CELLS
Authors: Kessler Ketty , Mackay Alan , Molinari Valeria , Tari Haider , Burford Anna , Sottoriva Andrea , Vinci Maria , Jones Chris
Published: December 2020

Diffuse intrinsic pontine glioma (DIPG) and other diffuse midline glioma (DMG) are characterised by K27M mutations in histone H3 variants. The major functional consequence is a global loss of the repressive mark H3K27me3, causing a raft of transcriptional changes promoting tumorigenesis, although certain key loci retain trimethylation, such as CDKN2A/B. We recently identified subclonal loss-of-function mutations in the H4 lysine methyltransferase KMT5B to be associated with an enhanced invasion/migration, but the mechanism by which this occurred was unclear. Here we show by ChIP-seq using patient-derived subclonal DIPG models and CRISPR-Cas9 depletion that loss of KMT5B (or KMT5C) causes a paradoxical increase in global levels of H4K20me3 in promoters and regulatory regions, only ablated by knocking out both enzymes. Loss of KMT5B alone further causes loss of the majority of otherwise retained H3K27me3 loci in DIPG cells, although CDKN2A/B itself was spared. De-repression occurred at bivalent loci marked by H3K4me3 and had elevated gene expression by RNAseq; these were significantly enriched for genes involved in chromatin remodelling and invasion/migration, the latter including MMP9/MMP24. Phenotypic assessment of the models in vitro by high-throughput imaging demonstrated significantly increased invasion and migration in association with either KMT5B or KMT5C loss, but not both. Quantitative proteomic assessment of the secretome identified factors by which a minority of KMT5B-deficient cells may signal to promote motility of the neighbouring populations. These data suggest a previously unrecognised trans-histone (H4/H3) interaction in DIPG cells with a potentially profound effect on their diffusely infiltrating phenotype.
EPCO-07. LEVERAGING TRANSCRIPTOME SEQUENCING AND MATHEMATICAL MODELING TO INVESTIGATE GLIOBLASTOMA-MACROPHAGE INTERACTIONS
Authors: Urcuyo Javier , Hawkins-Daarud Andrea , Massey Susan , Bruce Jeffrey , Canoll Peter , Tran Nhan , Hu Leland , Swanson Kristin
Published: December 2020

Glioblastoma (GBM) is the one of the most aggressive and common primary brain malignancies, with a poor median overall survival of less than 15 months. While the immune system is activated and brain-resident microglia and blood-derived macrophages combat the tumor, the tumor can convert some microglia and macrophages to instead exhibit an immune-suppressive phenotype. These co-opted immune cells are thereby termed ‘glioma-associated microglia and macrophages’ (GAMMs), as they allow for continued tumor growth. However, limited clinical data has been collected to understand this phenomenon. As a result, we have collected spatially-distributed image-localized biopsies from a cohort of patients and performed RNA sequencing on each sample. Correlations between normalized RNA counts of genetic markers for macrophages (i.e., CD68, CD163), tumor populations (i.e., SOX2, OLIG2), and key cell functions (i.e., KI67, CASP3) were analyzed. To further investigate the temporal effects that GAMMs have on GBM growth, we proposed the Proliferation-Invasion-Macrophage (PIM) model. This system of partial differential equations incorporates the proliferative and invasive behavior of GBM, as well as populations for both ‘healthy’ and ‘glioma-associated’ macrophages. By exploring the parameter space, we classified the various dynamics of tumor progression and how they relate to the immune response. With further insights of the interactions between GBM and macrophage populations, we can begin to parameterize the model on a patient-specific basis and provide insights to personalized immunotherapies and other novel immune-targeted treatments.
EPCO-11. IN VIVO FUNCTIONAL GENOMIC SCREEN IDENTIFIES WISP1 AS AN OVEREXPRESSED DRIVER OF GLIOBLASTOMA
Authors: Dasgupta Pushan , Gumin Joy , Pettazzoni Piergiorgio , Barthel Floris , Deem Angela , Dey Prasenjit , Huang-Hobbs Emmet , Sulman Erik , Verhaak Roel , Lang Frederick , Draetta Giulio
Published: December 2020

There is a tremendous need to identify new genetic drivers of glioblastoma which can serve as potential therapeutic targets. In order to find new drivers, we leveraged genomic datasets to conduct a context specific in vivo functional genomic screen of overexpressed and/or amplified genes in GBM. We identified WISP1, a secreted extracellular matrix protein, to be an overexpressed driver in GBM. Overexpression of WISP1 was able to drive tumor growth in various in vivo models. Knockdown of WISP1 with shRNAs resulted in reduced colony formation in vitro and reduced tumor growth in vivo. Rescue experiments validated that the shRNAs were on target. Functional characterization of the protein revealed that the TSP module is necessary for the phenotype. Intriguingly, overexpression of WISP1 lacking the signal peptide module for secretion resulted in a strong phenotype. Co-culture and conditioned medium experiments further supported a secretion independent intracellular role of WISP1 in GBM. Though WISP1 is a secreted protein we have found some basal localization in the cytosol. Overall, we have revealed WISP1 to be a driver of GBM with possible therapeutic potential as a target. This study has expanded our understanding of WISP1 by supporting a new role as a driver in GBM which can function in a non-canonical manner in the cytosol. Overall, we have revealed WISP1 to be a driver of GBM with possible therapeutic potential as a target.
EPCO-13. GENOME-WIDE ASSOCIATION STUDY IN INDIVIDUALS OF ASHKENAZI JEWISH ANCESTRY IDENTIFIES NOVEL RISK LOCI FOR GLIOMA
Authors: Ostrom Quinn , Byun Jinyoung , Amos Christopher , Claus Elizabeth , Bondy Melissa
Published: December 2020

Population stratification, or systematic differences in allele frequencies between subpopulations, can distort the results from genome-wide association studies (GWAS). While GWAS are usually conducted within continental (e.g. European) ancestry groups, sub-groups may have specific population histories that result in enrichment for risk or protective alleles for complex disease. In this analysis, we examined genetic risk for glioma in a US population with predominantly Ashkenazi Jewish (AJ) ancestry. Genotyping data were obtained from three prior glioma case-control studies. Best-guess assignment to one of seven subcontinental European ancestry groups was performed using AIPS (https://github.com/biomedicaldatascience/AIPS). Out of a total of 6,416 cases and 7,441 controls across all three studies, 202 cases (3% of all cases, 63% GBM) and 403 controls (5% of all controls) were assigned to the AJ ancestry group. Unconditional logistic regression was performed for by study (adjusted for age and first two principal components) and then studies were combined using fixed effects meta-analysis. No associations reached genome-wide significance (p< 5x10-8), including those detected in prior pan-European GWAS. A nominally significant association was detected on chromosome 17 in ASPA (rs9904040, MAF=20%, p=2.61x10-6, Odds ratio=2.22 [95% confidence interval=1.59–3.09]) which is in linkage equilibrium (r2=0.0013) with the previously detected glioma risk SNP in TP53 (MAF=0.3% in this analysis, p=0.8801) in the European population. In our prior pan-European meta-analysis (Melin et al., 2017, this SNP was non-significant (p=0.0620). This study failed to replicate many previously identified glioma risk alleles, likely due to diminished power due to small sample size. We did identify a novel risk allele on chromosome 17 in ASPA, which encodes for aspartoacylase (which catalyzes deacylation of N-acetyl_L-aspartic acid). Larger sample sizes identified via targeted recruitment are necessary in order to fully characterize genetic risk for glioma in this population, including assessment of rare (MAF< 5%) risk allele associations.
EPCO-15. TUMOR TREATMENT WITH IONIZING RADIATION IS ASSOCIATED WITH A CLINICALLY RELEVANT DELETION SIGNATURE
Authors: Kocakavuk Emre , Anderson Kevin , Johnson Kevin , Varn Frederick , Amin Samirkumar , Barthel Floris , Verhaak Roel
Published: December 2020

Diffuse gliomas are highly aggressive brain tumors that invariably relapse despite treatment with chemo- and radiotherapy. Treatment with alkylating chemotherapy can drive tumors to develop a hypermutator phenotype. In contrast, the genomic effects of radiation therapy (RT) remain unknown. We analyzed the mutational spectra following treatment with ionizing radiation in sequencing data from 190 paired primary-recurrent gliomas from the Glioma Longitudinal Analysis (GLASS) dataset and 2249 post-treatment metastatic tumors from the Hartwig Medical Foundation. We identified a significant increase in the frequency of small deletions following radiation therapy that was independent of other factors. These novel deletions demonstrated distinct characteristics when compared to pre-existing deletions present prior to RT-treatment and deletions in RT-untreated tumors. Radiation therapy-acquired deletions were characterized by a larger deletion size (GLASS and metastatic cohort, P = 1.2e-02 and P = 8e-11, respectively; Mann-Whitney U test), an increased distance to repetitive DNA elements (P < 2.2e-16, Kolmogorov-Smirnov test) and a reduction in microhomology at breakpoints (P = 3.2e-02, paired Wilcoxon signed-rank test). These observations suggested that canonical non-homologous end joining (c-NHEJ) was the preferred pathway for DNA double strand break repair of RT-induced DNA damage. Furthermore, radiotherapy resulted in frequent chromosomal deletions and significantly increased frequencies of CDKN2A homozygous deletions. Finally, a high burden of RT-associated deletions was associated with worse clinical outcomes (GLASS and metastatic cohort, P = 4.7e-02, HR = 2.59 [95% CI: 1.01, 6.60] and P = 2.5e-02, HR = 1.43 [95% CI: 1.05, 1.94], respectively; multivariable Cox regression), suggesting that effective repair of RT-induced DNA damage is detrimental to patient survival and that inhibiting c-NHEJ may be a viable strategy for improving the cancer-killing effect of radiotherapy. Taken together, the identified genomic scars as a result of radiation therapy reflect a more aggressive tumor with increased levels of resistance to follow up treatments.
EPCO-16. LACTIC ACID IS AN EPIGENETIC METABOLITE THAT DRIVES GLIOBLASTOMA SURVIVAL AND GROWTH
Authors: Torrini Consuelo , Nguyen Trang , Shu Chang , Mela Angeliki , Humala Nelson , Mahajan Aayushi , Karpel-Massler Georg , Bruce Jeffrey , Canoll Peter , Siegelin Markus
Published: December 2020

Glioblastoma (GBM) is the most common primary malignant brain tumor with an unfavorable prognosis and a reprogrammed metabolism. While tumors utilize glucose, there are other carbon sources at their disposal. Originally considered as a waste product of glucose catabolism, lactate accumulates to a significant amount in tumor tissue. We launched our studies with the central hypothesis that lactate is metabolized by GBM cells to promote their survival via modulation of the epigenome. We showed that lactate rescued patient-derived xenograft (PDX) GBM cells from nutrient deprivation mediated cell death and inhibition of growth. Transcriptome analysis, Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq), and CHIP-seq. showed that lactic acid exposure entertained a signature of cell cycle progression, oxidative phosphorylation (OXPHOS) and MYC target expression. LC/MS analysis demonstrated that U-13C-Lactate elicited substantial labeling of TCA-cycle metabolites, acetyl-CoA and histone protein acetyl-residues in PDX derived GBM cells. Given that acetyl-CoA is pivotal for histone acetylation we observed a dose-dependent elevation of histone marks (e.g. H3K27ac), which was rescued by genetic and pharmacological inhibition of lactic acid-uptake, ATP-citrate lyase, p300 histone-acetyl-transferase and OXPHOS, resulting in reversal of lactate mediated protection from cell death or facilitation of GBM growth. CHIP-seq. analysis demonstrated that lactic acid facilitated enhanced binding of H3K27ac to gene promoters and cis-regulatory elements (e.g. super-enhancers). Consistently, ATAC-seq. analysis highlighted enhanced accessibility of the chromatin by lactic acid. Finally, we assessed whether lactic acid is actively metabolized in vivo, utilizing an orthotopic PDX model of GBM. In a combined tracer experiment (U-13C-glucose and 3-C13-lactate), we made the fundamental observation that lactic acid carbons were predominantly labeling the TCA cycle metabolites over glucose, implying a critical role of lactic acid in GBMs and establishing lactic acid metabolism as a novel drug target for GBM that may be targeted with epigenetic drugs.
EPCO-19. INTEGRATED ANALYSIS OF INTRA-TUMORAL HETEROGENEITY IN GLIOBLASTOMAS THROUGH SINGLE NUCLEI ATAC-SEQ AND RNA-SEQ
Authors: Raviram Ramya , Raman Anugraha , Preissl Sebastian , Ning Jianfang , Wu Shaoping , Deynze Kinsey , Chen Clark , Ren Bing
Published: December 2020

Glioblastoma, the most common form of primary brain cancer in adult, consists of an ecosystem of cancer cells characterized by cell-to-cell variations in genotypes and phenotypes. This intra-tumoral heterogeneity forms the substrate for cancer evolution, which in turn fuels therapeutic failure and resistance. To better define this heterogeneity, we profiled clinical glioblastoma specimens using single nuclei assays for Transposase-Accessible Chromatin with sequencing (snATAC-seq), RNA-Seq (snRNA-Seq), Paired snATAC/snRNA-seq, and whole genome-seq (WGS). We found that snATAC-Seq detected focal amplifications (~40kb-2MB) of genomic regions, revealing magnitudes of intra-tumoral heterogeneity previously unappreciated. snATAC-seq and WGS provided high resolution chromatin-state maps of extrachromosomal DNA (ecDNA), while Paired-seq delineated gene expression patterns associated with these chromatin-states. sn-RNAseq confirmed distinct cell states previously defined by others, including oligodendrocyte progenitor cell (OPC), neural progenitor cell (NPC), astrocyte, and mesenchymal -like glioblastomas. Analysis of snATAC-seq profiles in this context revealed shared dependency of these cell states on the Nuclear Factor 1 complex (NFIA and NFIB). Our results demonstrate the utility of cross-platform integration of single cell genomic technologies and suggest that, despite the overwhelming genotypic and phenotypic heterogeneity, shared vulnerability of predominant glioblastoma cell states can be identified.
EPCO-21. STING PROMOTER EPIGENETIC SILENCING IN GLIOBLASTOMA
Authors: Low Justin , Bowie Michelle , Chandramohan Vidya , Fuller Rebecca , Muscat Andrea , Brown Michael , Hariharan Seethalakshmi , Hostettler Janell , Briley Aaron , Danehower Sarah , Baker Ali , Wong Nick , Ashley David
Published: December 2020

The Stimulator of interferon genes (STING) protein is a critical component of the innate immune response to pathogenic and cytosolic self DNA. The importance of STING signalling has recently been demonstrated in a number of tumor types, including glioblastoma (GBM), and its activation through STING agonism is a promising antitumor therapeutic avenue. Recent studies have shown a loss of STING expression in cancer and an overall dysregulation of the CGAS/STING pathway. A potential mechanism of STING silencing is the methylation of its promoter. Using bulk methylation array data from patient samples, we explore epigenetic control of the TMEM173 gene that encodes STING. We find that the STING promoter is highly methylated in glioblastoma and that STING RNA expression is correspondingly low. Methylation data from normal brain and non-cancer cerebral diseases reveal a consistent pattern of STING promoter hypermethylation in these diverse states. The degree of bulk STING methylation in GBM samples inversely correlates with tumor purity and markers of immune infiltration. Single-cell transcriptome sequencing reveals that STING is expressed specifically in immune cells and endothelial cells, but not glioma cells. Collectively these results suggest that STING signalling is disrupted in GBM, that STING is epigenetically silenced by DNA methylation in the tumor, and that STING expression in bulk GBM tumor samples arises from infiltrating immune cells in the tumor microenvironment. Therapeutic approaches stimulating the innate STING signalling pathway are therefore likely to be effective on infiltrating immune cells rather than tumor cells themselves. This work motivates further study into mechanisms of STING activation in the broader GBM tumor microenvironment.