LAUSR

Introduction: Tumor treating fields (TTF) are used for treatment of glioblastoma. Its utilization for spinal metastasis has never been described. We investigate the anti-mitotic effect of TTF to inhibit the growth of human cancer cells in vitro and in vivo models of spinal metastasis. Methods: In vitro: human derived osteosarcoma (Krib-luc-1) and lung adenocarcinoma (A549-luc) cells were seeded in 5 × 3mm human demineralized bone grafts kept in culture while treated with 0kHz (control) or 150kHZ of TTF for 14 days. Bioluminescence images (BLI) were obtained at baseline and 14 days. In vivo: Krib-Luc-1 cells were surgically implanted via transperitoneal approach to L3 vertebra in nude mice. Animals were treated with 0kHz or 150kHz for 30 days or until death. BLI were obtained at day 0 and every 7 days. MRI was obtained at day 22. Histological analysis was performed at the end of the experiment. Control and TTF-treated groups were compared with two-tailed t-tests. Results: In vitro: BLI of the control groups demonstrated 5-fold and 34-fold higher tumor signal (photons/sec) than corresponding 150 kHz TTF treatment groups at 14 days (A549 p=0.0289; KRIB p=0.00895). In vivo: All mice receiving 0 kHz treatment displayed hind limb paralysis by day 30, while mice treated with 150 kHz TTF displayed tail drop or no signs of paralysis. MRI and histology confirmed smaller tumors corroborating to BLI (3.67-fold change in photons/sec) (p=0.0212) when the 150 kHz TTF treatment group was compared to controls. Conclusions: Application of TTF at 150kHz reduced cellular proliferation in both in vitro and in vivo models of spinal metastasis. This is the first report of utilization of TTF for treatment of bony tumors and represents the first evidence that TTF could become a revolutionary therapy for spinal metastasis. Citation Format: Claudio Esteves Tatsui, Daniel Ledbetter, Christopher Alvarez-Breckenridge. In vitro and in vivo investigation of tumor treating fields for treatment of spinal metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 20.