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e14631 Background: Phosphoglycerate kinase 1 (PGK1) has been detected overexpressed in many malignancies and usually correlated with increased tumorigenesis and poor survival. Our previous study revealed that PGK1 significantly up-regulated and positively correlated with cofilin-1 (CFL1) expression in radioresistant astrocytomas samples. However, the further mechanism remains unknown. Methods: In the present study, functional interactions among PGK1, chronophin (CIN) and CFL1 were analyzed by co-immunoprecipitation and immunofluorescence experiments. Transfection of shRNA and pcDNA3.1-plasmid were respectively utilized to silence and overexpress PGK1 or CIN in both normal glioma cells (U251 and U373) and estabilshed radioresistant (RR-U251 and RR-U373) cells. The effect of PGK1 on CIN and CFL1 expression levels was investigated with Western-blot method; while the effect of PGK1 or CIN on radiosensitivity of glioma cells was evaluated using cell viability, migration and invasion assays after irradiation. Results: Cell proliferation, migration and invasion abilities significantly increased in RR-U251 and RR-U373 cells compared with those of normal cells, indicating the successful establishment of RR-glioma cell models. Laser confocal experiment in vitro showed the colocalization of PGK1 and CIN. Meanwhile, PGK1 specifically and directly combined with CIN, while did not interplay with CFL1. Elevated PGK1 expression level was observed in radioresistant cells compared with that of normal cells. The western blot analysis showed that CFL1 and CIN levels were positively correlated with the PGK1 expression in both normal and radioresistant cells. The proliferation, migration and invasion capabilities significantly decreased in PGK1-silenced and CIN-silenced glioma cells, indicating the improvement of the radiosensitivity of radioresistant cells. Conclusions: Our research implied the effect of CIN-mediated PGK1 regulation on CFL1 level, thereby altering the migration and invasion abilities in nomal and notably radioresistant glioma cells. These findings clarify a novel underlying mechanism of radioresistance in glioma cells and provide valid basis for further explorations concerning radiotherapy.

2060 Background: Evidence is increasing for altered immune responses in malignant gliomas. Tumor-associated microglia/macrophages infiltrate human glioma tissue and produce cytokines that promote glioma growth, invasion and angiogenesis. Dimethyl fumarate (DMF), approved for relapsing-remitting multiple sclerosis, is toxic to in vitro activated microglial cells. Based on pre-clinical data demonstrating synergism with radiation (RT) and temozolomide (TMZ), we conducted a phase I study of DMF in patients with newly-diagnosed glioblastoma (GBM) in combination with RT and TMZ. Methods: Using a standard 3+3 dose escalation design (3 dose levels: 120 mg bid, 240 mg bid and 240 mg tid), newly-diagnosed GBM patients received daily DMF with RT (60 Gy) and concurrent TMZ 75 mg/m2 daily, followed by adjuvant DMF (continuously) and TMZ for up 6 maintenance cycles (150-200 mg/m2 on days 1-5 of each 28 day cycle). The maximum tolerated dose (MTD) was defined as the dose with ≤ 1/6 dose-limiting toxicities (DLT). The MTD was determined by evaluation of DLTs during the first 6 weeks of therapy. Results: Twelve patients were treated at the three dose levels, and no DLT was identified. There were no unexpected toxicities. The most common toxicities were lymphopenia (11 grade 3/4 events) and thrombocytopenia (2 grade 3/4 events). The only grade 3/4 non-heme toxicity was a grade 3 hemorrhoid event. Of the 12 evaluable patients, one remains on active treatment in maintenance phase. Three patients completed all treatment (concurrent and maintenance) with stable disease. Two patients had a partial response (RANO criteria) but then experienced disease progression during maintenance. Five patients had disease progression during study treatment and one patient chose to withdraw from the study during maintenance. Conclusions: These data suggest that DMF may be safely combined with RT and TMZ in GBM patients. A phase II study is under consideration. Clinical trial information: NCT02337426.

e22214 Background: In human glioma (U118, SF767) cell membranes,sphingomyelin (SM) levels are lower and phosphatidylethanolamine (PE) levels are higher compared to non-tumor (MRC5) cells. This memb...

2072 Background: Human glioma stem cells and xenograft lines are common translational models in neuro-oncology but it has not been established if they are genetically and phenotypically comparable. This study aimed to determine if human glioma xenografts and stem cell-derived tumors had similar genotypes. Methods: Matched glioma stem cell cultures and subcutaneous xenograft lines were generated from four human glioblastoma specimens (BT114, BT116, BT120, BT132). Comparison was made between subcutaneous stem cell-derived tumors (flank) and xenografts established in nude mice. Copy number variation (CNV) and gene expression microarray studies were performed. Results: Various differences in copy number and gene expression were seen. Observed CNVs included regions within EGFR, myc, and p16 (INK). For example, EGFR copy number was two fold higher in xenografts vs. stem cell-derived tumor in one line (BT114). This difference was corroborated by western blot. Other differences included a heat shock protein homolog (DNAJA4), tetraspanin 13, and a p53 family target gene (ISG20L1). Two lines (BT114, BT116) had a greater than two fold increase in DNAJA4 expression in xenografts vs. stem cell-derived tumors (p = 0.04, 0.01). Two cell lines (BT116, BT120) had a two to eight fold increase in tetraspanin 13 expression in xenografts (p = 0.02, 0.05). However, neither copy number nor gene expression variations were consistent across all cell lines. Conclusions: Xenografts and glioma stem cell-derived tumors established from the same patient specimens have distinct genotypes. Further work is needed to establish if these differences are random or represent characteristic changes selected by different in vitro or in vivo pressures. However, these variations raise questions regarding which model is ideal for studying glioma biology, and which ones best replicate glioma characteristics in human patients.

2044 Background: Prognosis remains poor for glioma and therefore requires new approaches. We have previously developed a genetically-engineered strain of Salmonella typhimurium, A1-R, that targets tumors without overt toxicity in mouse models (Proc. Natl. Acad. Sci. USA 102, 755-760, 2005; Cancer Research 66, 7647-7652, 2006; Proc. Natl. Acad. Sci. USA 104, 10170-10174, 2007; Expert Opinion on Drug Discovery 7, 73-83, 2012). In the present study, we demonstrated that Salmonella typhimurium A1-R can inhibit and eradicate human glioma in an orthotopic nude mouse model. Methods: S. typhimuirum A1-R was administered by injection through a craniotomy open-window or intravenously in nude mice. To establish the model, 2×105 U87 human glioma cells, expressing red fluorescent protein (RFP), were injected stereotactically into the mouse brain through the craniotomy open window. Two weeks after glioma-cell implantation, mice were treated with S. typhimurium A1-R (2×107 CFU / 200 μl intravenous injection [i.v.] or 1×106 CFU / 1 μl intracranial injection [i.c.]) once a week for 3 weeks. Results: Brain tumors were observed by fluorescence imaging through the craniotomy open window over time. S. typhimurium A1-R, administered i.c., inhibited brain tumor growth 7.6-fold compared with untreated mice (p = 0.009) and improved survival 73% (p = 0.001). Two of ten mice had their tumors eradicated. Intravenous administration of S. typhimurium A1-R was not effective. Conclusions: The results of the present study demonstrate that bacterial therapy of glioma is a novel, effective and safe treatment strategy in a highly treatment-resistance cancer in an orthothopic model, a first step toward clinical development.

e12524 Background: Glioblastoma multiforme (GBM) is one of the deadliest forms of cancer, with an average survival time of approximately one year despite aggressive surgery, radiotherapy and chemot...

2083 Background: Sagopilone (ZK-EPO) is a fully synthetic epothilone that exhibits activity in MDR tumors, and has demonstrated antitumor activity in orthotopic human glioma models in vivo. This 2-...

11506 Background: ATO is effective in the treatment of acute promyelocytic leukemia, but its role in the management of solid tumors has yet to be defined. Post-operative therapy consisting of TMZ with and without RT is considered the standard of care for patients with newly-diagnosed glioblastoma multiforme (GBM). ATO has been shown to potentiate the effects of RT in preclinical models. Therefore, we investigated the cytotoxicity of ATO and TMZ both together and in combination with RT in the U251T human glioma cell line. Methods: U251T cells in log phase growth were treated with ATO (0.05–5 μM) and/or TMZ (0.05–5 μM) for 24 hours or sequentially according to the following schedules: ATO for 18 hours followed by TMZ for 6 hours or the reverse sequence. For RT experiments, cells were treated with 0–10 Gy of ionizing RT using a Cesium-137 source. Following drug and/or RT treatment, cells were replated onto 1.5 cm tissue culture dishes in triplicate and incubated at 37oC for 8 to 10 days to form colonies. Colonies of more than 40 cells each were counted and the IC50 values and combination indices (CI) were derived using Calcusyn software (Biosoft, Cambridge, UK). Each combination was repeated at least 3 times. Results: The mean single agent IC50 for ATO, TMZ, and RT were 1.10 ± 0.28 μM, 1.88 ± 0.91 μM, and 2.62 ± 0.23 Gy, respectively. Simultaneous treatment with ATO and TMZ was slightly synergistic, while sequential treatment was either additive (TMZ→ATO) or synergistic (ATO→TMZ). Combinations of RT with ATO, TMZ or both were all synergistic, with the triple agent combination showing the greatest synergy. Conclusions: RT followed by ATO and TMZ given sequentially demonstrated striking synergy in U251T human glioma cells. A clinical trial of this combination therapy in patients with newly-diagnosed GBM is currently under development. [Table: see text] No significant financial relationships to disclose.

9522 Background: Gliomas are among the most lethal of human tumors. A hallmark genomic feature of gliomas is the presence of complex chromosomal aberrations that result in altered gene copy numbers...