bluuebunny/crossref_metadata_2025_split huggingface dataset:
P11.19 Glioblastoma cancer stem cells proliferation and cell cycle arrest under TTFields influence
Authors: Mazzanti M , Verduci I , Cannavale G , Pyromali I , Poloni R , Rampini D 
Published: September 2019

Abstract

BACKGROUND
Glioblastoma (GBM) is the most aggressive and fastest growing-type among brain tumours. The current standard of care is a combination of surgery, radio- and chemotherapy. However, GBM is characterized by a poor prognosis and an average life expectancy of 15 months under current treatment. Tumor treating fields (TTFields) are low-intensity electric fields alternating at an intermediate frequency (200kHz), which have been demonstrated to block cell division and interfere with organelle assembly. It has been evaluated in randomized phase 3 trials in GBM and demonstrated to prolong progression-free survival and overall survival when administered together with standard maintenance temozolomide (TMZ) chemotherapy in patients. This technology represents the biggest step forward against GBM in more than a decade.

METHODS
Primary cultures of human glioblastoma enriched in cancer stem cells (GSCs) were stimulated using the InovitroTM System (NOVOCURE) for 72 hours. Remaining cells were collected for further experiments.

RESULTS
Our investigation has targeted GSCs, a subset of cells that are considered responsible for tumour recurrence and confer resistance to chemotherapy and radiotherapy. Our data show that after 72 hours of TTFields exposure, more than 60% of the cellular population are dead. The residual GSCs were able to recover proliferation as soon as TTFields application had ended. We used different combinations of TTFields exposure times and pharmacological treatments with the main objective to impair cell proliferation relapse. Prolong TTF stimulation kills more cells but survivor cells are still able to resume proliferation. The addition of 10 mM TMX increase drastically the efficacy of the TTFields treatment even if the few cells left were able to slowly form colonies in a single cell cloning assay.

CONCLUSION
GCSs are sensitive to TTFields and to the combining pharmacological treatment with TMZ. The strategy to optimize the antiproliferative action on GCSs relapse will be to find a best combination of anticancer drugs concentration, together with TTFields exposure.
P11.21 Treating numerous secondary tumors in the brain with tumor treating fields: Simulation study to identify optimal transducer array layout
Authors: Kinzel A , Yesharim O , Naveh A , Bomzon Z 
Published: September 2019

Abstract

BACKGROUND
Tumor Treating Fields (TTFields) use alternating electric fields for the treatment of solid tumors. The therapy is approved for glioblastoma multiforme (GBM), and a phase III trial in 1–10 brain metastases from non-small cell lung cancer (METIS) is currently enrolling patients. In GBM, the layout of the transducer arrays delivering the TTFields to the tumor is optimized for high field intensity in the tumor, while the dose in other regions is decreased. In the setting of secondary brain tumors, as they manifest as brain metastases in 10–30 % of adult cancer patients - especially in melanoma, lung, breast, colon, and kidney cancer - a high TTFields dose in the entire brain would be beneficial. Thus, numerous tumors instead of only one lesion should receive therapeutic TTFields doses. In this study, transducer array layouts aiming for a homogeneous TTFields distribution in the whole brain were investigated.

MATERIAL AND METHODS
We used computer simulations in a realistic computational head model of a 40+ years old man, constructed in-house from a T1 MRI series, to compute the field distributions obtained with various transducer array layouts. The distribution of TTFields delivered by pairs of transducer arrays at different positions on the head and neck was simulated using Sim4Life v3.0 (ZMT Zürich). For each layout, we determined and compared the mean and median field intensities in five pre-determined sections of the brain: (1) the cerebellum and brain stem together with other infra-tentorial anatomical regions; and (2–5) the four cerebral quadrants.

RESULTS
One array layout could be identified yielding median intensities between 1.5 V/cm to 1.7 V/cm in all areas and a homogeneous distribution within the brain. This layout is composed of one pair of arrays positioned on the right temple and left scapula, and the other pair positioned on the left temple and right scapula.

CONCLUSION
This study was able to determine a novel TTFields transducer array layout that might be used for treatment of the entire brain with therapeutic intensities, as would be beneficial in patients with brain metastases.
P11.22 Radiotherapy effects in GBM Rat model CNS1
Authors: Furman O , Daniels D , Guez D , Last D , Sharabi S , Talianski A , Mardor Y , Zach L 
Published: September 2019

Abstract

BACKGROUND
CNS1 is a syngeneic glioma model in Lewis Rats. It is an aggressive infiltrating tumor cell line that mimics important aspects of human GBM such as rapid growth, dispersal along blood vessels and white matter, pseudopallisading cells with features of hemorrhage and necrosis. CNS1 tumors are infiltrated with macrophages and T-cells, and were studied in the context of immunotherapy and gene therapy, extracellular matrix and invasion, but CNS1 response to radiation has not yet been described. If we wish to combine novel immune-based therapies with existing GBM protocols that include radiation and chemotherapy, we will need models that respond to these protocols. As a first step in this direction, we sought to describe CNS1 response to radiation in vitro and in vivo.

MATERIAL AND METHODS
In vitro, survival of irradiated CNS1 cells was assessed with clonogenic assay. Radiation varied in dose from 0 to 10 Gy and was delivered via Kimtron Polaris X-ray generator. In vivo, male Lewis rats were intra-cranially inoculated with 0.5*106 CNS1 tumor cells and monitored for survival. Treated rats (N=6) were subjected to a single 20Gy whole-head radiation treatment under full anesthesia, delivered five days post-inoculation. Control rats (N=5) were anesthetized but not irradiated. Tumor size was monitored using contrast enhanced T1-weighted MRI in both treated and control rats at several time points (4, 6, 11, 18 and 32 days post tumor inoculation).

RESULTS
CNS1 cells are sensitive to radiation in vitro, as cell survival decreased after exposure to increasing amounts of radiation. In vivo, while initial tumor size did not significantly differ between groups, rats treated with radiation survived significantly longer than control rats (23.8 ± 5.0 days vs. 11 ± 4.1 days, p<0.005). Growth arrest following irradiation in vivo was not detected 1d after treatment but was observed 6d post-irradiation. Growth arrest was recorded in half of the treated rats, showing no increase in tumor size (N=2) or reduction in tumor volume (N=1) relative to 1d post-irradiation. Tumor growth rates were lower in all irradiated rats relative to control rats. Survival time was negatively correlated with initial tumor size in the control group but not in the treatment group.

CONCLUSION
CNS1 rat model of GBM is a valid model of radiotherapy effects on GBM tumors. Further studies combining radiation and chemotherapy are the next step. Support for this work was provided by Israel Cancer Association.
P11.28 Alteration of blood brain barrier (BBB) permeability by Tumor Treating Fields (TTFields) in vivo
Authors: Keßler A F , Salvador E , Domröse D , Burek M , Tempel Brami C , Voloshin Sela T , Giladi M , Ernestus R , Löhr M , Förster C , Hagemann C 
Published: September 2019

Abstract

BACKGROUND
Alternating electric fields with intermediate frequency (100 - 300 kHz) and low intensity (1 - 3 V/cm), known as Tumor Treating Fields (TTFields), have been established as a novel adjuvant therapy for glioblastoma (GBM) patients. The blood brain barrier (BBB) tightly controls the influx of the majority of compounds from blood to brain. Due to this regulation, the BBB may block delivery of drugs for treatment of brain tumors, in particular GBM. In this study, we investigated the influence of TTFields on BBB permeability in vivo.

MATERIAL AND METHODS
For determination of BBB permeability, rats were treated with 100 kHz TTFields for 72 h. At the end of treatment, rats were i.v. injected with Evan′s Blue (EB), which binds Albumin (~70 kDa) upon injection to the blood. EB was extracted after brain homogenization and quantified at 610 nm. In addition, cryosections of rat brains were prepared following TTFields application at 100 kHz for 72 h, and sections were stained for Claudin 5, Occludin and immunoglobulin G (IgG) to assess vessel structure. Moreover, serial dynamic contrast-enhanced DCE-MRI with Gadolinium contrast agent (Gd) was performed before and after TTFields application.

RESULTS
In vivo, the EB accumulation in the brain was significantly increased by application of TTFields to the rat head. Claudin 5 and Occludin staining was visible in vessel endothelial cells and localized at the cells’ edges in control cryosections of rat brains. In TTFields-treated rats, the vessel structure became diffuse; Claudin 5 and Occludin were delocalized and IgG was found throughout the brain tissue and not solely inside the vessels, as it is normally the case. Serial DCE-MRI demonstrated significantly increased accumulation of Gd in the brain, detected directly after 72 h of TTFields application. 96 h after end of TTFields treatment the effect on the BBB disappeared and no difference in contrast enhancement between controls and TTFields treated animals was observable.

CONCLUSION
Application of TTFields at 100 kHz could have the potential to deliver drugs to the brain, which normally are unable to cross the BBB by altering BBB integrity and permeability. Utilizing TTFields to open the BBB and its subsequent recovery, as demonstrated by the data presented herein, could lead to a clinical approach of drug delivery for treatment of malignant brain tumors and other diseases of the central nervous system. These results will be further validated in clinical trials.
P11.37 Evaluating water content and electrical properties at 200 kHz in brain and GBM tumor tissue of three TTFields patients with conventional imaging
Authors: Bomzon Z , Wenger C , Hershkovich H K , Tempel Brami C , Giladi M 
Published: September 2019

Abstract

BACKGROUND
Electrical properties (EPs) of brain tissue, specifically brain tumors, crucially determine the field distribution of Tumor Treating Fields (TTFields), an anti-mitotic treatment approved for glioblastoma multiforme (GBM). Due to the correlation of TTFields efficacy and field intensity at the tumor region, the knowledge of EPs in each patient is of great importance for patient-specific planning of treatment. Water content electrical properties tomography (wEPT) is a non-invasive imaging technique using water content (WC) maps obtained from rapidly acquired and processed conventional sequences to estimate the EPs of brain tissue at 128 MHz. The WC maps of this approach are constructed from two spin echo sequences similar to a T1 and a PD image. Following previous studies in rat tumor models demonstrating promising wEPT mapping of EPs in the brain at 200, this study examines the feasibility of this approach in human GBM patients.

MATERIAL AND METHODS
For three patients of the EF-14 trial population, we divided T1 and PD images pixel-by-pixel to obtain the image ratio. Using a transfer function, WC maps were generated and maps of the electrical conductivity σ and the relative permittivity ε r at 200 kHz were calculated with two different equations.

RESULTS
The median value of estimated WC remains similar in healthy brain tissues among all patients, ~73.5% in the white matter, ~82% in the gray matter. The median values of wEPT-estimated σ at 200 kHz in the white matter is ~0.09 S/m and in the gray matter ~0.18 S/m, corresponding median values of ε r at 200 kHz are ~2100 and ~3000 in white and gray matter respectively. Contrary, in the tumor the spread between the median values of WC and EPs is much higher. Stating the most important findings, in the necrosis median WC are 90.3%, 92.3%, 85.2% in patients 1–3 respectively with corresponding median σ values of 0.494, 0.657, 0.25 S/m. In the enhancing tumor the spread of median WC is even higher (67.2%, 83.6%, 85.5%), yet lower spread but also very heterogeneous median σ values of 0.075 S/m, 0.208, 0.259 S/m are estimated with wEPT.

CONCLUSION
Our results demonstrate the adaption of wEPT for mapping of WC and EPs at 200 kHz in three human GBM patients. In contrast to the vastly irregular tumor tissue, our estimations in healthy brain tissue are similar between patients and in accordance with EPs experimentally measured during our animal experiments and consistent with reported values in the literature. Hence, wEPT is a promising, fast technique based on regular MRI that might help patient-specific treatment planning of TTFields therapy, although the mapping of tumor tissue needs further confirmation in a greater population and investigations of EPs of excised tumor tissue samples should be conducted.
P11.44 Conception of a promising future therapy: Drug loaded-microbubbles against glioblastoma
Authors: Schulz E , Mawamba V , Sturm V , Ernestus R , Schatzschneider U , Löhr M , Hagemann C 
Published: September 2019

Abstract

BACKGROUND
Major obstacles for an effective chemotherapy of glioblastomas (GBM) are the blood-brain-barrier (BBB) and serious systemic side effects of the cytotoxic drugs. A new promising strategy could be the delivery of microbubbles, encapsulating the chemotherapeutics, across the BBB to the tumor site. This will shield the drug from detrimental systemic effects. Low intensity focused ultrasound (LIFU) is able to open the BBB and triggers targeted release of the drugs within the tumor. First data on the synthesis of microbubbles, specifically designed new drugs and the targeted rupture of microbubbles by LIFU are presented.

MATERIAL AND METHODS
Thin-film hydration of lipids was utilized to prepare microbubbles, which were tested for toxicity on the GBM cell lines GaMG, U87, U138 and U343. In addition these cells were treated with 6 platinum(II) and palladium(II) complexes conjugated to lipophilic side chains of different length (C1, C8, C10) for 72h. To evaluate cell viability and calculate EC50 values MTT assays and a real-time proliferation assay using the impedance-based xCELLigence DP-System were executed.

RESULTS
Microbubbles ≤ 2µm in diameter were synthesized and could be disintegrated by applying LIFU. Neither the intact bubbles nor the lipids alone had any toxic effects on the GBM cells. In contrast, all six drugs were highly effective with EC50 values far below those of Temozolomide (67µM) and in the range of the reference drug cisplatin (3µM). Especially the palladium(II) compound with the C1-chain displayed a very low EC50 value (<10µM), while the longer chains and the platinum(II) compounds were less effective (EC50 10–40µM). An early and concentration-dependent onset of the cytotoxic effect of drugs with C1 and C8 side chains was revealed in the real time proliferation assay.

CONCLUSION
All components for a new microbubble-based therapeutic strategy are in place. Microbubbles were synthesized without having toxic effects in cell culture. New highly potent palladium(II) and platinum(II) compounds with low EC50 values were developed. The next step will be their encapsulation into the microbubbles via their lipophilic side chains to develop an effective drug-delivery system for the treatment of GBM in combination with LIFU. This will allow increasing the local concentration of chemotherapeutic agents at the tumor site, irrespectively of their molecular size and BBB penetration capacity.
P11.55 Thymoquinone enhances the sensitivity of B16-F10 melanoma cell line to Gamma Knife radiosurgery
Authors: Hatiboglu M A , Kocyigit A , Guler E M , Akdur K , Khan I , Nalli A , Karatas E , Tuzgen S 
Published: September 2019

Abstract

BACKGROUND
Melanoma patients with brain metastasis have poor prognosis. Gamma Knife radiosurgery (GKR) is an effective treatment to control brain metastasis from melanoma. Thymoquinone (TQ) has gained attention as a potential therapeutic option due to its anti-tumor effects on various cancers. The aim of the study was to invetsigate the effect of GKR in B16-F10 melanoma cells in vitro and in established intracerebral melanoma model in mice in vivo, and the sensitizing efficacy of TQ towards GKR.

MATERIAL AND METHODS
Effects of GKR and combination treatment of GKR and TQ were studied on B16-F10 melanoma cells via analyzing cytotoxicty by adenosine triphosphate (ATP) assay; apoptosis induction by acridine orange staining and genotoxicity by comet assay. Expression of STAT3, p-STAT3 (Tyr705) and apoptotic pathway proteins was investigated by western blot analysis. Enzyme Linked Immunosorbent Assay (ELISA) was performed to assess the expression of inflammatory cytokines. Also survival was evaluated in mice with brain tumor after GKR and its combination treatment with TQ.

RESULTS
The effects of GKR on cytotoxicity, apoptosis and genotxicity were significantly enhanced by TQ on B16-F10 melanoma cells. GKR induced apoptosis through inhibition of p-STAT3 expression, which subsequently regulated pro- and anti-apoptotic proteins such as caspase-3, Bax, Bcl-2, survivin. Combination TQ with GKR irradiation enhanced the apoptotic effect of GKR irradiation. Furthermore, GKR decreased the levels of tumor-related inflammatory cytokines on B16-F10 melanoma cells. This effect was more pronounced when TQ was added to GKR irradiation. GKR with 15 Gy improved the survival of mice with intracerebral melanoma compared to untreated mice. Although, the additive effect of TQ in combination with GKR irradiation on B16-F10 melanoma cells in vitro, TQ did not add any significant survival benefit to GKR treatment in mice with intracerebral melanoma.

CONCLUSION
Our findings indicate that TQ would be a potential therapeutic and sensitizing agent in addition to GKR to enhance the anti-tumor effect of irradiation. Further studies are required to support our findings.
P11.58 Astrocytic Environment Aid the Evolution of Immunosuppressive Environment in Glioblastoma
Authors: Heiland D H , Ravi V M , Behringer S P , Schnell O 
Published: September 2019

Abstract

BACKGROUND
Glioblastomas are referred to as immunologically “cold” tumors since their cellular environment promotes an anti-inflammatory environment leading to an unresolved barrier to immunotherapy. Although the role of reactive astrocytes in other inflammatory diseases has been investigated in several studies, the immunoregulatory functions of astrocytes in the tumor environment remains poorly understood.

MATERIAL AND METHODS
We purified reactive astrocytes from de-novo glioblastoma and non-infiltrated cortex specimens by immunoprecipitation and analyzed the transcriptional phenotype by RNA sequencing. In order to investigate the origin of astrocytic transformation, we used a microglia loss-of-function model in human organotypic slices. Microglia was depleted by clodronat stimulation. We injected tumor cells and analyzed gene expression of the astrocytes after 7d incubation by RNA sequencing. Environmental cytokines were analyzed by multi-ELISA. Immunostainings of slices were processed by confocal microscopy and 3D reconstruction.

RESULTS
Here we address the immunological impact of tumor-associated astrocytes, we were able to identify a novel reactive subtype marked by JAK/STAT pathway activation and CD274 expression. Our results show a distinct astrocytic transcriptional phenotype that mutually arises from both microglia and astrocytes of the tumor environment. This interaction leads to a large release of anti-inflammatory cytokines such as TGFß and IL10. The reactive subtype switch of astrocytes was recovered by inhibition of the JAK pathway, which caused an increase of pro-inflammatory environment.

CONCLUSION
Our results can form the basis for a novel therapeutic approach by directly targeting tumor-associated astrocytes in order to transformimmunologically “cold” into “warm” tumors.
P11.62 Brain distribution models to select polymer-delivered drugs for the intra-cavity treatment of malignant glioma
Authors: Rowlinson J , McCrorie P , Smith S , Barrett D , Kim D , Grundy R , Scurr D , Rahman R 
Published: September 2019

Abstract

BACKGROUND
Conventional oral or intravenous chemotherapy distributes drugs to the whole body whereby systemic toxicity to healthy parts of the body (e.g. bone marrow failure) limits the maximum dose that can be achieved in the brain. This presents a particular concern for CNS tumours where the blood-brain-barrier (BBB) restricts drug influx from the circulation. The ability to deliver chemotherapy locally at the tumour site offers the opportunity to target residual cancer cells post-surgery whilst minimising systemic toxicity. We have developed a poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) polymer matrix that forms a porous paste at room temperature when mixed with chemotherapy-containing saline, solidifying only at body temperature, with close apposition to the irregular surgical cavity. It is important that we can observe whether the drugs released from PLGA/PEG can penetrate brain parenchyma beyond the surgical resection margin at therapeutic doses. Currently the only way to measure the distribution of drugs in the body is to inject radioactive drugs into an animal. We aim to establish drug distribution parameters using label-free mass spectrometry imaging methods, prior to selection of drug formulations for clinically-relevant in vivo models. Drugs that penetrate the brain the furthest will be identified as good candidates for localised brain cancer drug delivery using PLGA/PEG paste.

MATERIAL AND METHODS
Diffusion rates were measured by examining the proportion of olaparib, dasatnib, carboplatin, etoposide, paclitaxel and gemcitabine at 2mg/ml concentration, which passes through 1mm slices of rat brain tissue within Franz cell chambers over a 6 hour period. The spatio-temporal distribution of label-free olaparib and dasatinib within mouse brain homogenate was quantitatively measured using innovative 3D OrbiSIMS, a hybrid time-of-flight / OrbitrapTM secondary ion mass spectrometer.

RESULTS
Within the Franz cell model, carboplatin and gemcitabine showed the highest diffusion rate diffusion at 16.4 and 6.53 µg/cm2/h respectively whereas olaparib, etoposide and paclitaxel were relatively poorly diffused at 1.87, 3.82 and 2.27 µg/cm2/h respectively. The minimum threshold of OrbiSIMS detection for label-free olaparib and dasatinib ions was 0.025 mg/ml and 0.2 mg/ml respectively throughout brain homogenate.

CONCLUSION
This study demonstrates different diffusion rates through brain tissue, between label-free chemotherapy drugs of distinct chemistries, with highest diffusion rates observed for carboplatin and gemcitabine. We also demonstrate label-free detection of olaparib and dasatinib using the innovative 3D OrbiSIMS method. These models will facilitate the rapid identification of agents most amenable for localised biomaterial-based chemotherapy delivery with high brain penetrance.