bluuebunny/crossref_metadata_2025_split huggingface dataset:
CSIG-05. S6K FEEDBACK REGULATION OF THE RECEPTOR TYROSINE KINASE AXL IN PTEN-DEFICIENT GLIOBLASTOMA
Authors: Sarma Pranjal , Ennis Kelli N , Wetzel Collin , Plas David R 
Published: December 2020

Abstract
Glioblastoma multiforme (GBM), the most aggressive type of malignant brain cancer in adults, harbors frequent mutations and/or deletions in the tumor suppressor gene PTEN leading to therapeutic resistance. In PTEN-deficient GBM, mTOR complex 1 (mTORC1) and the S6 kinases (S6Ks) mediate increased metabolism and apoptosis resistance. Previously we established that combining the LY-2584702 inhibitor of S6K1 with the BMS-777607 inhibitor of the AXL receptor tyrosine kinase (RTK) was selectively cytotoxic for PTEN-deficient GBM. Here we determined the impact of these inhibitors on S6K1 and S6K2 signal transduction and tumor cell metabolism. While combination of LY-2584702 with BMS-777607 was sufficient to prevent S6K phosphorylation of ribosomal protein S6 (rpS6), treatment with either drug as a single agent was not sufficient to suppress rpS6 phosphorylation. Genetic inactivation of S6Ks revealed that inactivation of S6K2 cooperated with LY-2584702 to prevent S6K substrate phosphorylation. Similarly, persistent S6K signaling in BMS777607-treated GBM cells was significantly reduced when S6K2 was targeted. These results indicate that S6K2 integrates signal transduction inputs from both PTEN-regulated and AXL-regulated pathways. Metabolomic analysis revealed combination effects of S6K and AXL inhibitors in reducing nucleotide precursor metabolic flux. We therefore propose that combination inhibition of S6K and AXL signaling compromises S6K-dependent nucleotide synthesis in PTEN-deficient GBM.
CSIG-07. c-Src PHOSPHORYLATES AND INACTIVATES THE CIC TUMOR SUPPRESSOR PROTEIN IN GLIOBLASTOMA
Authors: Bunda Severa , Heir Pardeep , Li Annie , Yasin Mamatjan , Zadeh Gelareh , Aldape Kenneth 
Published: December 2020

Abstract
Capicua (CIC) is a transcriptional repressor that counteracts activation of genes in response to receptor tyrosine kinase (RTK)/Ras/MEK/ERK signaling. Following activation of RTK, ERK enters the nucleus and serine-phosphorylates CIC, releasing it from its targets to permit gene expression. We recently showed that ERK triggers ubiquitin-mediated degradation of CIC in glioblastoma (GBM). In this study, we examined whether another important downstream effector of RTK/EGFR, the non-receptor tyrosine kinase c-Src, affects CIC repressor function in GBM. We found that c-Src binds and tyrosine phosphorylates CIC on residue 1455 to promote nuclear export of CIC. On the other hand, CIC mutant allele (CIC-Y1455F), that escapes c-Src-mediated tyrosine phosphorylation, remains localized to the nucleus and retains strong repressor function against CIC targets, the oncogenic ETV transcription factors. Furthermore, we show that the orally available Src family kinase inhibitor, dasatinib, which prevents EGF-mediated tyrosine phosphorylation of CIC and attenuates elevated ETV levels, reduces viability of GBM cells and glioma stem cells (GSC), but not of their control cells with undetectable c-Src activity. In fact, GBM cells and GSC expressing the tyrosine-defective CIC mutant (Y1455F) lose sensitivity to dasatinib, further endorsing the effect of dasatinib on Src-mediated tyrosine phosphorylation of CIC. Importantly we show that combined inhibition of Src and MEK/ERK results in greatest stabilization of CIC and attenuation of proliferation compared to either inhibitor alone. These findings elucidate important mechanisms of CIC regulation and provide the rationale to target c-Src alongside ERK pathway inhibitors as a way to fully restore CIC tumor suppressor function in neoplasms such as GBM.
CSIG-08. TARGETING ION TRANSPORT-REGULATORY KINASES AS A NOVEL TREATMENT FOR GLIOBLASTOMA
Authors: Schiapparelli Paula , Meade Paola Suarez , Miranda-Herrera Pierre , Bechtle Alexandra R , Issacs Farren , Levchenko Andre , Rinehart Jesse , Quinones-Hinojosa Alfredo 
Published: December 2020

Abstract
Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Currently, treatment is focused on achieving maximal safe resection, followed by chemo- and radiotherapy. Although surgery remains the most important therapeutic component, complete surgical resection is virtually impossible, as GBM cells readily infiltrate the adjacent brain parenchyma. One fundamental mechanism for GBM cell migration is the ability of these cells to use cell volume regulation as a driving force of cell infiltration and potentially interfering with apoptosis and cell cycle progression. In this work, we targeted the master regulators of cell volume, the kinases STE20/SPS1-Related Proline-Alanine-Rich Protein Kinase (SPAK) and Oxidative stress-responsive kinase-1) (OSR1) by using a novel proprietary small molecule inhibitor. In order to study the effects of inhibiting SPAK and OSR1, we analyzed cell proliferation and migration. First, we determined the IC50 using six different patient-derived GBM cell lines; we found IC50 values ranging from 0.2–2μM. Next, cell proliferation was determined by cell cycle analysis through Edu labeling. We found a significant decrease in S phase and cell cycle arrest in G2M (p= 0.001, n=6). In addition, cell migration was determined using boyden chamber assay. We found a dose-dependent reduction in cell migration (p=0.001, n=3). These results correlated with the phenomenon observed in an orthotopic murine model of GBM, in which the inhibitor showed a decrease in tumor growth (p=0.0026, n=4) and greater survival rates in vivo (p=0.0046, n=8). When used in combination with radiation therapy, this small molecule inhibitor was capable of radio-sensitizing GBM cells decreasing clonogenicity (p=0.01, n=3) were observed in vitro. In summary, by targeting the SPAK/OSR1 kinases with a small molecule inhibitor, GBM cells become less aggressive, mainly by interfering with cell migration and proliferation and becoming more sensitive to radiation.
CSIG-09. ATRX DEFICIENCY IN GLIOMA IMPACTS TRANSCRIPTIONAL PROFILES AND THE IMMUNE MICROENVIRONMENT IN VIVO
Authors: Irvin David , Roberts Hannah , Sharin Vladislav , Farooqi Ahsan , Dharmaiah Sharvari , Alvarez Christian , Huse Jason 
Published: December 2020

Abstract
Current treatment for diffuse astrocytoma fails to address its underlying molecular mechanisms leading to inevitable disease progression and eventual patient death. Genomic studies have implicated ATRX alterations as critical to low grade glioma biology. Our lab has previously shown in vitro that ATRX influences glioma motility, cellular differentiation state, and epigenetic programming, however, the influence of ATRX alterations in vivo remains unclear. Here, we leveraged an RCAS/tva mouse tumor model to probe the role of ATRX deficiency in glioma. Atrx deficient murine tumors exhibited lower histopathological grade and were associated with longer survival than Atrx-intact counterparts, and syngeneic allografts of cell lines derived from primary tumors mirrored the differential degrees of aggressiveness seen in primary tumors. Tumor-derived Atrx-deficient cell lines showed increased susceptibility to G-quadruplex stabilizing compounds, pointing to increased replication stress and recapitulating a key phenotype of ATRX-mutant gliomas in humans. Transcriptional profiling revealed enrichments in MYC target genes, E2F targets as well as G2/M checkpoint pathways in Atrx-intact tumors and cells, and enrichment in RAS signaling in Atrx-deficient tumors and cells. Finally, Atrx deficient murine gliomas displayed increased levels of NK cells, a phenotype recapitulated in ATRX-mutant human gliomas, and primary Atrx-deficient glioma lines exhibited increased levels of NK cell-attracting cytokines. These latter findings suggest that ATRX deficiency could influence interactions between glioma cells and their immune microenvironment by way of phenotypically relevant molecular mechanisms.
CSIG-10. GENOTYPE – KINOME GUIDED DEVELOPMENT OF PRECISION EGFR-TARGETED THERAPEUTICS FOR GLIOBLASTOMA
Authors: Smithberger Erin , Shelton Abigail , Butler Madison , Stamper Allie , Bash Ryan , Angus Steven , East Michael , Johnson Gary , Berens Michael , Furnari Frank , Miller C Ryan 
Published: December 2020

Abstract
Glioblastoma (GBM) is an aggressive primary brain tumor with poor survival and limited treatment options. However, it is an attractive candidate for precision therapeutic approaches due to the frequency of amplification and/or activating mutations in the epidermal growth factor receptor (EGFR) gene and the availability of several brain penetrant second- and third-generation EGFR tyrosine kinase inhibitors (TKI). We used comprehensive molecular profiling of a panel of genetically engineered mouse astrocyte models to examine whether mutational profiles, particularly EGFR and PTEN status, could be used to identify kinases upregulated in specific mutational backgrounds. Using RNA-seq and multiplex inhibitor bead/mass spectrometry (MIB-MS) to analyze the kinase transcriptomes and proteomes, respectively, we have identified several potential targets for combination therapy. Overexpression of wild type EGFR in immortalized, Cdkn2a-/- astrocytes resulted in mild rewiring of the GBM kinome. Only 5 kinases aside from EGFR itself were overexpressed on either the transcript or protein levels. One overexpressed kinase, Hck, has been shown to be involved in cell survival, proliferation, adhesion, and migration. In contrast, overexpression of EGFRvIII, a constitutively active, extracellular domain truncation mutant of EGFR, resulted in significant alteration of the GBM kinome – 81 kinases showed differential expression, with 27 upregulated. One potentially attractive target among these was Cdk6, a drug-targetable, prognostically significant cyclin-dependent kinase implicated in proliferation, migration, and invasion. Finally, overexpression of EGFRvIII in cells lacking Pten dysregulated 46 kinases, including 15 upregulated. One particularly interesting target in these cells was Ddr2, a tyrosine kinase involved in migration, invasion, and extracellular matrix remodeling. We conclude that Hck, Cdk6, and Ddr2 represent attractive targets for therapeutic intervention in their relevant genetic contexts. These findings also suggest that molecular diagnostics for EGFR and PTEN status may be useful in guiding development of rational, EGFR TKI-centric drug combinations.
CSIG-12. HDACs-Sp1-BMI1 PATHWAY IS INVOLVED IN THE ATTENUATION OF STRESS- AND THERAPY-INDUCED DEATH IN GLIOMA
Authors: Lo Wei-Lun , Tsai Yu-Ting , Chuang Jian-Ying 
Published: December 2020

Abstract
BMI-1 is a transcriptional repressor and overexpresses in various human cancer tissues, which is also known to involve in the maintenance of “stem cell” features in a cell sub-population within the tumor. Here, we investigate the roles of BMI1 oncogene in brain tumors, notably involving drug-resistant metabolism. Interestingly, microarray datasets in OMCOMINE indicated that BMI1 is not commonly increased in clinical brain tumors, and survival plots in PROGgeneV2 also showed that BMI1 expression is not statistically associated with glioma patients. However, stressful serum starvation and anchorage independence growth conditions enabled to induce upregulation of BMI1. Further investigation, we identified HDAC-Sp1 is a stress-responsive pathway, critically promoting BMI1 expression. HDAC inhibition via vorinostat treatment prevented the binding of Sp1 to BMI1 promoter, leading to decreased BMI1 expression and attenuated tumor growth of TMZ-resistant glioma xenografts. Importantly, increased expression of the HDAC-Sp1-BMI1 axis but not BMI1 alone showed an increased risk of death in both high- and low-grade glioma. Thus, the HDAC-Sp1-BMI1 axis is critical to attenuate stress- and therapy-induced death in glioma cells and the axis inhibition may prevent the recurrence of malignant cells persisting after primary therapy.
CSIG-17. PRMT5 INHIBITION SENSITIZES GLIOBLASTOMA MODELS TO TRAMETINIB TREATMENT
Authors: Otani Yoshihiro , Namagiri Sriya , Thammegowda Shilpa , Sur Hannah , Chowdhury Ashis , Lewis Cole , Shimizu Toshihiko , Lee Tae Jin , Maric Dragan , Yoo Ji Young , Heiss John , Kaur Balveen , Banasavadi-Siddegowda Yeshavanth Kumar 
Published: December 2020

Abstract

INTRODUCTION
Glioblastoma (GBM) is the most common malignant primary brain tumor. With limited effective therapeutic strategies, prognosis for GBM is very poor. Our previous study shows that the expression of Protein Arginine Methyltransferase 5 (PRMT5) is upregulated in GBM; its inhibition promotes anti-GBM effect through apoptosis and senescence of mature and immature tumor cells, respectively. In GBM, RAS-RAF- MEK-ERK signaling is aberrantly activated and promotes tumor growth. Therefore, MEK inhibitors, including trametinib are currently under investigation for GBM therapy. In this study, we tested whether inhibition of PRMT5 can enhance the anti-tumor efficacy of trametinib in GBM.

METHODS
Patient-derived primary GBM neurospheres (GBMNS) with transient PRMT5 knockdown were treated with trametinib and cell viability, proliferation, cell cycle progression, and western blot analysis were conducted. In vivo, PRMT5-intact and -depleted GBMNS were intracranially implanted in NSG mice and treated with trametinib by daily oral gavage, and tumor progression and mice survival rate were analyzed by MRI and Kaplan-Meier survival curve, respectively.

RESULTS
Trametinib treatment upregulated the expression of PRMT5 in GBMNS. Depletion of PRMT5 increased the cytotoxic effect of trametinib in GBMNS. In concurrence with the trametinib-induced PRMT5 upregulation, trametinib treatment increased the activity of AKT that was blocked with PRMT5 knockdown. In vivo, PRMT5-depletion extended the survival of the tumor bearing mice that further increased in combination with trametinib treatment. Interestingly, trametinib treatment alone had no survival benefit.

CONCLUSION
Trametinib treatment induces PRMT5 expression. Depletion of trametinib-induced PRMT5 expression sensitizes GBMNS for trametinib by inhibiting AKT activity.
CTIM-04. UPDATES FOR A PHASE 2 OPEN-LABELED STUDY OF PEMBROLIZUMAB PLUS TTFIELDS PLUS MAINTENANCE TEMOZOLOMIDE IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA (2-THE-TOP)
Authors: Ghiaseddin Ashley , Warren Sonisha , Allen Annie , Sampson Deborah , Chen Dongjiang , Sherman Alexandra , Greene Valerie , Rahman Maryam , Tran David 
Published: December 2020

Abstract

INTRODUCTION
Tumor-treating fields (TTFields) are a new standard anti-mitotic treatment for newly diagnosed glioblastoma (ndGBM). Emerging data indicate that TTFields also stimulate innate immunity, leading to adaptive immunity. We hypothesize that immune checkpoint inhibitors synergize with TTFields to promote anti-tumor immunity in ndGBM.

METHODS
24 adult patients with ndGBM will be enrolled following radiotherapy with concurrent temozolomide. To identify TTFields-induced immune effects that are augmented by pembrolizumab, TTFields (200 kHz) is started with cycle 1 of maintenance TMZ while pembrolizumab (200mg Q3W) is added at cycle 2 and continued up to 2 years or until disease progression or unacceptable toxicities. The primary endpoint is PFS vs. historical controls (JAMA, 318:2306–2316). Secondary endpoints include toxicity/tolerability and immune activation by TTFields before and after pembrolizumab as determined by single-cell analysis of peripheral blood mononuclear cells.

RESULTS
As of 06/19/2020, there are 17 evaluable patients. The median follow-up is 12.2 months from cycle 1 of maintenance TMZ. 10 (59%) patients are progression-free, and 13 (76%) are alive. Of 9 patients with follow-up &gt; 12 months, the median PFS is at least 11.2 months vs. historical median PFS of TTFields plus maintenance TMZ of 6.7 months. The most common serious adverse events are pain, weakness, lymphatic swelling, and metabolic disturbances observed in 3 (18%), 2 (12%), 2 (12%), and 1 (6%) patients, respectively. In response to TTFields, we detect a 2.26 (p=0.01) and 5.2-fold (p=0.07) mean increase in the number of classical and plasmacytoid dendritic cells (DC), respectively. Network analysis shows wide-spread pathway upregulation in responders, especially type 1 interferon response genes in DC (FDR=0.02) and cytotoxicity genes in CD8 T cells (FDR=0.03).

CONCLUSIONS
Pembrolizumab in combination with TTFields plus maintenance TMZ is generally well tolerated in patients with ndGBM. Preliminary data demonstrates activation of adaptive immunity and improved efficacy and will be updated.
CTIM-05. COMBINATION OF CONTROLLED INTERLEUKIN-12 GENE THERAPY WITH IMMUNE CHECKPOINT BLOCKADE IN RECURRENT GLIOBLASTOMA: UPDATED RESULTS OF A MULTI-INSTITUTIONAL, OPEN LABEL PHASE 1 TRIAL
Authors: Antonio Chiocca E , Lukas Rimas , Chen Clark , Rao Ganesh , Amidei Christina , Buck Jill , Hadar Nira , Demars Nathan , Miao John , Estupinan Taylor , Loewy John , Wang Yunxia , Gelb Arnold , Cooper Laurence 
Published: December 2020

Abstract
A published clinical trial of veledimex (V)-regulatable interleukin-12 (IL-12) gene therapy (“Controlled IL-12”) under the control of a transcriptional switch (RheoSwitch Therapeutic Systemâ, RTSâ) as monotherapy in recurrent glioblastoma (rGBM) showed sustained infiltration of activated T cells within the tumor months after treatment (Sci Transl Med. 2019;11(505)). These T cells demonstrated up-regulation of immune checkpoint signaling, providing a rationale for combination therapy with the PD-1 inhibitor, nivolumab (nivo). We report interim findings following completion of enrollment (with follow-up ongoing) for a multi-institutional, open label, dose-escalation phase 1 trial (NCT03636477) evaluating safety and tolerability of loco-regional Controlled IL-12 in combination with nivo in adults with rGBM. Replication-incompetent adenovirus coding for RTS-IL-12 (Ad) was administered during surgery by free-hand injection into the tumor and periphery (2 x 1011 viral particles, Day 0) accompanied by V (10 or 20 mg) PO QD x 15 (Days 0 to 14) in combination with nivo (1 or 3 mg/kg) IV on Days -7, 15, then Q2W. Twenty-one subjects were treated (Cohort 1: V 10 mg, nivo 1 mg/kg, n=3; Cohort 2: V 10 mg, nivo 3 mg/kg, n=3; and Cohort 3: V 20 mg, nivo 3 mg/kg, n=3 & 12 in expansion). Safety data were comparable to Ad+V monotherapy. Adverse reactions (ARs) during follow-on nivo dosing were consistent with nivo labeling. ARs were manageable and generally reversible with no synergistic toxicities. Updated overall survival findings will be presented. Baseline and post-treatment histochemical staining and multiplex immunofluorescence analyses for a subgroup of subjects will be discussed. The safety of this combination immunotherapy has been established, leading to a currently accruing phase 2 clinical trial of loco-regional Controlled IL-12 gene therapy in combination with the PD-1 inhibitor cemiplimab-rwlc (NCT 04006119).
CTIM-09. DOUBLE-BLINDED, PLACEBO CONTROLLED PHASE 2 STUDY OF ERC1671 IN RECURRENT GLIOBLASTOMA: VACCINE OVERALL SURVIVAL IN BEVACIZUMAB NAIVE AND BEVACIZUMAB RESISTANT PATIENTS
Authors: Bota Daniela , Taylor Thomas , Kong Xiao-Tang , Fu Beverly , Hsu Frank , Strik Ankie , Schijns Virgil , Stathopoulos Apostolos 
Published: December 2020

Abstract
ERC1671 is an allogeneic/autologous therapeutic vaccine – composed of whole, inactivated tumor cells mixed with tumor- cell lysates. The hypothesized action of ERC1671 is to potentiate the patients’ immune system against the tumor. Goals of this ongoing, phase 2 study are to determine the safety and effectiveness (overall survival) of ERC1671 in combination with GM-CSF and cyclophosphamide as an add-on treatment to bevacizumab at the time of GBM recurrence. To date 22 recurrent bevacizumab-naïve rGBM patients have been randomized to ERC1671/GM-CSF/Cyclophosphamide + Bevacizumab or Placebo + Bevacizumab. Median age is 56.5 (33–74), 7 patients (32%) are female, and average KPS is 82.3 (70–100). Of the 22, two discontinued before completing one cycle of therapy and two remain on blinded treatment. Currently 18 patients are unblinded due to further progression: 8 were on vaccine and 10 on placebo. Five of those on placebo crossed to vaccine at progression. All but one of the 18 are now deceased. Median overall survival of unblinded patients randomized to ERC1671 + Bevacizumab (n = 8) is 264.5 days from the start of study treatment, compared to 182 days for those randomized to placebo + Bevacizumab who did not cross over (n = 5). Median overall survival of unblinded patients on vaccine at randomization or crossover is 328 days after first study treatment (n = 13). While sparse, the data to date suggest pre-treatment and maximal CD4+T lymphocyte count in the peripheral blood correlate with OS more strongly in the ERC1671 group than in the placebo group. First clinical results for toxicity show no difference in the distribution of AEs between the Vaccine and Placebo groups, with no Gr4/Gr5 AEs in either group. This phase 2 randomized, double-blinded study is ongoing, with the addition of one more site.
CTIM-11. PHASE I/II STUDY TO EVALUATE THE SAFETY AND CLINICAL EFFICACY OF ATEZOLIZUMAB (ATEZO) IN COMBINATION WITH TEMOZOLOMIDE (TMZ) AND RADIATION IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA (GBM)
Authors: Weathers Shiao-Pei , Kamiya-Matsuoka Carlos , Harrison Rebecca , Liu Diane , Sanqui Edmund , Dervin Shannon , Yun Cindy , Loghin Monica , Penas-Prado Marta , Majd Nazanin , Yung W K Alfred , O’Brien Barbara , de Groot John 
Published: December 2020

Abstract

BACKGROUND
Immunotherapy strategies such as PD-1/PD-L1 inhibition may work synergistically with radiation, which is known to increase antigen presentation and promote a pro-inflammatory tumor microenvironment. This trial evaluated the safety and clinical efficacy of concurrent atezo (anti-PD-L1) with radiation therapy and TMZ followed by adjuvant atezo and TMZ in patients with newly diagnosed GBM, unselected for MGMT status.

METHODS
Eligibility criteria included patients age &gt; 18 yrs who had undergone only surgery. The primary endpoint was safety in Phase I (n = 10) and OS in Phase II (n = 50). Secondary endpoints included progression free survival (PFS), overall response rate (ORR), and duration of response. All 60 patients were evaluated for efficacy. Correlative endpoints include profiling tumor immune cell populations, peripheral blood for circulating chemokines/cytokines, and stool for gut microbiome.

RESULTS
60 patients were enrolled. With a median follow-up time of 17.1 months (data cutoff = 15 April 2020), 37 patients have progressed, of which 30 patients have died. Median OS was 19 months (95% CI: 14.9, not reached). Median PFS was 10.6 months (95% CI: 8.2–16.7). Median OS in MGMT methylated patients (n = 18) was 29.9 months (95% CI: 11.4, not reached) and 16.3 months (95% CI: 13.9, not reached) in MGMT unmethylated patients (n = 33). Treatment-related adverse events with maximum CTCAE grade &gt; 3 occurred in 33 patients; the most common were LFT elevation (n = 5) and lymphopenia (n = 23). To date, 20 of the enrolled 60 patients underwent re-resection post atezo treatment. The matched paired tumor analysis of pre and post treatment tissue will provide valuable insights into mechanisms of anti-PD-L1 therapy resistance. Tumor immunocorrelative studies are pending.

CONCLUSIONS
Concurrent use of atezo with radiation and TMZ was tolerable and demonstrated efficacy in line with published trials for newly diagnosed GBM.