Abstract 5808: Designing arrays for delivering tumor treating fields (TTFields) to the mouse head
Authors: Zbidat Sewar , Blatt Roni , Sellevoll Mariell , Gabay Martin , Schlachet Inbar , Cahal Shay , Davidi Shiri , Tzchori Itai , Haber Adi , Giladi Moshe , Palti Yoram 
Published: March 2024

Abstract
Introduction: Tumor Treating Fields (TTFields) therapy is an approved treatment for glioblastoma (GBM), the most abundant malignant brain tumor. TTFields therapy is delivered to patients suffering from GBM continuously by two array pairs placed on their scalp. Since arrays for TTFields application to the mouse head are lacking, and as most GBM animal models are based on mice, in vivo studies of GBM treatment with TTFields are limited. The development of such arrays is challenging due to the small dimensions and specific geometries of the mouse head, but is needed to allow continued preclinical studies to broaden the understanding of the effects of TTFields on GBM.
Methods: We tested various array layouts to identify one that will be suited to the specific geometries of the mouse head. For animal well-being, the selected array was required to minimally restrict head movement. Additionally, we investigated adhesive tapes to allow on one hand good adherence of the arrays to the skin, and on the other hand easy array removal. To examine the feasibility of treating mice with these arrays, they were applied to mice for 11 days, while recording the electric currents and the actual treatment time (from which the percent usage could be calculated). To validate that the selected array layout delivers meaningful field intensity to the desired region, we performed field measurements using a floating scope.
Results: To tackle the limitation of the small head size, we developed an array layout in which only two arrays were situated on the head, while the opposing arrays were located on the mouse torso. Additionally, the arrays on the head were divided into two smaller disks. We also identified a thin and transparent adhesive tape (facilitating correct arrays positioning), that offered good tackiness and allowed easy removal without leaving residual adhesive on the skin. The arrays met the minimum treatment requirements: current ≥50 mA, usage ≥75%, field intensity ≥1 V/cm RMS. At the posterior side of the mouse head, at a location more directly underneath the arrays, field intensity was higher than at the anterior position.
Conclusion: TTFields could be delivered at sufficient intensities to mice heads by utilizing specifically engineered arrays. Our newly developed arrays are flexible and strongly adhering to enable efficient electric field delivery. By allowing TTFields delivery to mice heads, we will facilitate further advancing this research field.
Citation Format: Sewar Zbidat, Roni Blatt, Mariell Sellevoll, Martin Gabay, Inbar Schlachet, Shay Cahal, Shiri Davidi, Itai Tzchori, Adi Haber, Moshe Giladi, Yoram Palti. Designing arrays for delivering tumor treating fields (TTFields) to the mouse head [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5808.