Zeev Bomzon

Mitotic Spindle Disruption by Alternating Electric Fields Leads to Improper Chromosome Segregation and Mitotic Catastrophe in Cancer Cells

Tumor Treating Fields (TTFields) are low intensity, intermediate frequency, alternating electric fields. TTFields are a unique anti-mitotic treatment modality delivered in a continuous, noninvasive manner to the region of a tumor. It was previously postulated that by exerting directional forces on highly polar intracellular elements during mitosis, TTFields could disrupt the normal assembly of spindle microtubules. However there is limited evidence directly linking TTFields to an effect on microtubules. Here we report that TTFields decrease the ratio between polymerized and total tubulin, and prevent proper mitotic spindle assembly. The aberrant mitotic events induced by TTFields lead to abnormal chromosome segregation, cellular multinucleation, and caspase dependent apoptosis of daughter cells. The effect of TTFields on cell viability and clonogenic survival substantially depends upon the cell division rate. We show that by extending the duration of exposure to TTFields, slowly dividing cells can be affected to a similar extent as rapidly dividing cells.

Alternating electric fields (TTFields) in combination with paclitaxel are therapeutically effective against ovarian cancer cells in vitro and in vivo.

Long‐term survival rates for advanced ovarian cancer patients have not changed appreciably over the past four decades; therefore, development of new, effective treatment modalities remains a high priority. Tumor Treating Fields (TTFields), a clinically active anticancer modality utilize low‐intensity, intermediate frequency, alternating electric fields. The goal of this study was to evaluate the efficacy of combining TTFields with paclitaxel against ovarian cancer cells in vitro and in vivo. In vitro application of TTFields on human ovarian cancer cell lines led to a significant reduction in cell counts as compared to untreated cells. The effect was found to be frequency and intensity dependent. Further reduction in the number of viable cells was achieved when TTFields treatment was combined with paclitaxel. The in vivo effect of the combined treatment was tested in mice orthotopically implanted with MOSE‐LTICv cells. In this model, combined treatment led to a significant reduction in tumor luminescence and in tumor weight as compared to untreated mice. The feasibility of effective local delivery of TTFields to the human abdomen was examined using finite element mesh simulations performed using the Sim4life software. These simulations demonstrated that electric fields intensities inside and in the vicinity of the ovaries of a realistic human computational phantom are about 1 and 2 V/cm pk‐pk, respectively, which is within the range of intensities required for TTFields effect. These results suggest that prospective clinical investigation of the combination of TTFields and paclitaxel is warranted.

Modeling Tumor Treating Fields (TTFields) application in single cells during metaphase and telophase.

Effects of electric fields on biological cells have been extensively studied but primarily in the low and high frequency regimes. Low frequency AC fields have been investigated for applications to nerve and muscle stimulation or to examine possible environmental effects of 60 Hz excitation. High frequency fields have been studied to understand tissue heating and tumor ablation. Biological effects at intermediate frequencies (in the 100-500 kHz regime) have only recently been discovered and are now being used clinically to disrupt cell division, primarily for the treatment of recurrent glioblastoma multiforme. In this study, we develop a computational framework to investigate the mechanisms of action of these Tumor Treating Fields (TTFields) and to understand in vitro findings observed in cell culture. Using Finite Element Method models of isolated cells we show that the intermediate frequency range is unique because it constitutes a transition region in which the intracellular electric field, shielded at low frequencies, increases significantly. We also show that the threshold at which this increase occurs depends on the dielectric properties of the cell membrane. Furthermore, our models of different stages of the cell cycle and of the morphological changes associated with cytokinesis show that peak dielectrophoretic forces develop within dividing cells exposed to TTFields. These findings are in agreement with in vitro observations, and enhance our understanding of how TTFields disrupt cellular function.

Simplified realistic human head model for simulating Tumor Treating Fields (TTFields)

Tumor Treating Fields (TTFields) are alternating electric fields in the intermediate frequency range (100-300 kHz) of low-intensity (1-3 V/cm). TTFields are an anti-mitotic treatment against solid tumors, which are approved for Glioblastoma Multiforme (GBM) patients. These electric fields are induced non-invasively by transducer arrays placed directly on the patients scalp. Cell culture experiments showed that treatment efficacy is dependent on the induced field intensity. In clinical practice, a software called NovoTalTM uses head measurements to estimate the optimal array placement to maximize the electric field delivery to the tumor. Computational studies predict an increase in the tumors electric field strength when adapting transducer arrays to its location. Ideally, a personalized head model could be created for each patient, to calculate the electric field distribution for the specific situation. Thus, the optimal transducer layout could be inferred from field calculation rather than distance measurements. Nonetheless, creating realistic head models of patients is time-consuming and often needs user interaction, because automated image segmentation is prone to failure. This study presents a first approach to creating simplified head models consisting of convex hulls of the tissue layers. The model is able to account for anisotropic conductivity in the cortical tissues by using a tensor representation estimated from Diffusion Tensor Imaging. The induced electric field distribution is compared in the simplified and realistic head models. The average field intensities in the brain and tumor are generally slightly higher in the realistic head model, with a maximal ratio of 114% for a simplified model with reasonable layer thicknesses. Thus, the present pipeline is a fast and efficient means towards personalized head models with less complexity involved in characterizing tissue interfaces, while enabling accurate predictions of electric field distribution.

Using computational phantoms to improve delivery of Tumor Treating Fields (TTFields) to patients

This paper reviews the state-of-the-art in simulation-based studies of Tumor Treating Fields (TTFields) and highlights major aspects of TTFields in which simulation-based studies could affect clinical outcomes. A major challenge is how to simulate multiple scenarios rapidly for TTFields delivery. Overcoming this challenge will enable a better understanding of how TTFields distribution is correlated with disease progression, leading to better transducer array designs and field optimization procedures, ultimately improving patient outcomes.

Modelling Tumor Treating Fields for the treatment of lung-based tumors.

Tumor Treating Fields (TTFields), low-intensity electric fields in the frequency range of 100-500 kHz, exhibit antimitotic activity in cancer cells. TTFields were approved by the U. S. Food and Drug Administration for the treatment of recurrent glioblastoma in 2011. Preclinical evidence and pilot studies suggest that TTFields could be effective for treating certain types of lung cancer, and that treatment efficacy depends on the electric field intensity. To optimize TTFields delivery to the lungs, it is important to understand how TTFields distribute within the chest. Here we present simulations showing how TTFields are distributed in the thorax and torso, and demonstrate how the electric field distribution within the body can be controlled by personalizing the layout of the arrays used to deliver the field.

First steps to creating a platform for high throughput simulation of TTFields

Tumor Treating Fields (TTFields) are low intensity alternating electric fields in the 100-500 KHz frequency range that are known to have an anti-mitotic effect on cancerous cells. In the USA, TTFields are approved by the Food and Drug Administration (FDA) for the treatment of glioblastoma (GBM) in both the newly diagnosed and recurrent settings. Optimizing treatment with TTFields requires a deep understanding of how TTFields distribute within the brain. To address this issue, simulations using realistic head models have been performed. However, the preparation of such models is time-consuming and requires a high level of expertise, limiting the usefulness of these models for systematic studies in which the testing of multiple cases is required. Here we present a platform for rapidly simulating TTFields distributions in multiple scenarios. This platform enables high throughput computational simulations to be performed, allowing comparison of field distributions within the head in multiple clinically relevant scenarios. The simulation setup is simple and intuitive, allowing non-expert users to run simulations and evaluate results, thereby providing a valuable tool for studying how to optimize TTFields delivery in the clinic.

Abstract B79: Translational study of tumor treating fields in combination with paclitaxel in ovarian cancer.

Tumor Treating Fields (TTFields), a clinically active anticancer modality, are based on low intensity intermediate frequency alternating electric fields that exert their cytotoxicity by disrupting mitosis. The present study examines whether concomitant paclitaxel and TTFields have a beneficial impact on ovarian cancer growth both in vitro and in vivo. Moreover, on the basis of the preclinical observations, an open-label pilot clinical study evaluating the effect of the combined modalities in 30 patients with recurrent ovarian cancer was initiated. Preclinical studies: To investigate the inhibitory effect of TTFields on ovarian cancer cell growth in vitro and determine optimal therapeutic frequency of TTFields in ovarian cancer, human ovarian cancer cell lines were treated with TTFields (100-400 kHz) for 72 hours using the inovitro system (Novocure, Haifa, Israel). To assess whether adding TTFields to paclitaxel increases the response of ovarian cancer cells to paclitaxel, we treated these cell lines with paclitaxel alone and in combination with TTFields. In vivo efficacy of the combined treatment was tested in female C57Bl/6 mice, orthotopically implanted with MOSE-L FFL luciferase positive cells. The feasibility of effective regional delivery of TTFields therapy to the ovaries, pelvis and abdomen of human subjects was examined using Finite Element Mesh (FEM) simulations performed using the Sim4life software. The FEM simulations demonstrated effective distribution of fields at intensities of 1-2 V/cm, which is above the minimal threshold required for TTFields response. The INNOVATE Trial (NCT02244502): Based on positive preclinical studies demonstrating the combined efficacy of TTFields and paclitaxel in different ovarian cancer models, a pilot clinical trial was initiated to evaluate this therapeutic combination in recurrent ovarian carcinoma patients. In this prospective, pilot, single arm study, 30 patients will receive bi-directional TTFields at 200 kHz applied to the ovaries and surrounding intra-abdominal tissues using 4 transducer arrays located on the surface of the lower abdominal region. In addition, patients will receive concomitant paclitaxel at a standard regimen and dose. The combined treatment will be administered until further radiological progression. Inclusion criteria include ECOG score of 0-1 and no serious co-morbidities. The trial9s primary endpoint is adverse events frequency and severity. The study will also collect preliminary efficacy data through the analysis of progression-free survival, 1-year survival rate and overall survival. Compliance data will be analyzed as an additional secondary endpoint. The INNOVATE study started to enroll patients in October 2014, and is currently accruing patients in Switzerland, Belgium and Spain. So far the trial has enrolled half of the planned 30 patients. In summary, we present the first preclinical evidence in ovarian cancer of the combined efficacy of paclitaxel and TTFields, a new anticancer treatment modality. Our results suggest that it may represent a novel, effective therapeutic strategy against ovarian cancer. Pilot clinical testing is ongoing. Citation Format: Mijal Munster, Roni Blat, Paul C. Roberts, Eva M. Schmelz, Moshe Giladi, Rosa S. Schneiderman, Yaara Porat, Zeev Bomzon, Noa Urman, Aviran Itzhaki, Tali Voloshin, Shay Cahal, Eilon D. Kirson, Uri Weinberg, Yoram Palti. Translational study of tumor treating fields in combination with paclitaxel in ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B79.

Abstract 5361: In vitro results and electric fields simulations suggest Tumor Treating Fields (TTFields) to be an effective treatment against Mesothelioma

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Mesothelioma is an aggressive cancer affecting the membrane lining of the lungs and abdomen, and is associated with poor prognosis. Current available treatment options for Mesothelioma, including surgery, radiation therapy and chemotherapy, offer only modest improvement in survival, therefore emphasizing the desperate need for new treatment options. Tumor Treating Fields (TTFields) is a treatment modality based on non-invasive application of low intensity intermediate frequency alternating electric fields that disrupt mitosis. The goal of the present work was to determine whether TTFields in combination with standard of care drugs, could serve as an effective treatment against Mesothelioma. TTFields were applied to Mesothelioma cell cultures using the inovitro system. Cytotoxicity and effect on clonogenicity were determined following 72 hours of TTFields treatment. Combination index (CI) was calculated for the treatment of TTFields with each of the following drugs: Paclitaxel, Cisplatin, Pemetrexed and Vinorelbine. Finite Element Mesh (FEM) simulations were performed using the Sim4life software package (ZMT, Zurich, Switzerland) for the calculations of the electric fields intensities in the mesothelium of a realistic human computational phantom. Frequency titration experiments revealed 150 kHz to be the optimal TTFields frequency for Mesothelioma cell cultures, leading to 69% reduction in the number of cells (p<0.001) and 78% reduction in clonogenicity (p<0.05) as compared to control. The combined treatment of TTFields with Paclitaxel, Cisplatin, Pemetrexed and Vinorelbine resulted in combination index of 0.99, 0.88, 1.29 and 1.13, respectively. FEM simulations demonstrated that electric field intensities within the mesothelium are approximately 2 V/cm RMS which is above the minimal threshold required for TTFields effect. Taken together, these results suggest that combining TTFields therapy with systemic chemotherapy may be an approach that offers enhanced treatment efficacy for Mesothelioma. A clinical study testing the combined efficacy of TTFields Cisplatin and Pemetrexed is under development. Citation Format: Moshe Giladi, Mijal Munster, Roni Blat, Rosa Schneiderman, Yaara Porat, Zeev Bomzon, Noa Urman, Tali Voloshin, Eilon David Kirson, Uri Weinberg, Yoram Palti. In vitro results and electric fields simulations suggest Tumor Treating Fields (TTFields) to be an effective treatment against Mesothelioma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5361. doi:10.1158/1538-7445.AM2015-5361

Abstract CT082: TTFields concurrent with standard of care for the treatment of stage 4 non-small cell lung cancer (NSCLC) following platinum failure: phase III LUNAR study

Tumor Treating Fields (TTFields) are a non-invasive, anti-mitotic treatment modality. TTFields disrupt the formation of the mitotic spindle, and dislocation of intracellular constituents. TTFields significantly extend the survival of newly diagnosed glioblastoma patients when combined with temozolomide. Efficacy of TTFields in NSCLC has been shown preclinically and their safety in a phase I/II pilot study with pemetrexed. We hypothesize that adding TTFields to immune checkpoint inhibitor or docetaxel following platinum doublet failure will increase OS. Methods: Patients (N=534) with squamous or non-squamous NSCLC are enrolled in the LUNAR phase III study [NCT02973789]. Patients are stratified by their selected standard therapy (immune checkpoint inhibitors or docetaxel), histology (squamous vs. non-squamous) and geographical region. Key inclusion criteria are disease progression while on or after platinum-based systemic therapy, ECOG 0-2, no electronic medical devices in the upper torso, and absence of brain metastasis. Docetaxel or immune checkpoint inhibitors are given at standard doses. TTFields are applied to the upper torso for 18 hours/day, allowing patients to maintain daily activities. TTFields are continued until progression in the thorax and/or liver. Follow up is performed every 6 weeks, including CT scans of the chest and abdomen. On progression in the thorax and/or liver, patients have three post-progression follow up visits and are later followed monthly for survival. The primary endpoint is superiority in OS between patients treated with TTFields in combination with the standard of care treatments, compared to standard of care treatments alone. Key secondary endpoints compare the OS in patients treated with TTFields and docetaxel Vs. those treated with docetaxel alone, and patients treated with TTFields and immune checkpoint inhibitors Vs. those treated with immune checkpoint inhibitors alone. An exploratory analysis will test non-inferiority of TTFields with docetaxel compared to checkpoint inhibitors alone. Secondary endpoints include progression-free survival, radiological response rate, quality of life based on the EORTC QLQ C30 questionnaire and severity & frequency of adverse events. The sample size is powered to detect a HR of 0.75 in TTFields-treated patients versus control group. Citation Format: Uri Weinberg, Ori Farber, Moshe Giladi, Zeev Bomzon, Eilon Kirson. TTFields concurrent with standard of care for the treatment of stage 4 non-small cell lung cancer (NSCLC) following platinum failure: phase III LUNAR study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT082.