Abstract 1065: Concomitant dexamethasone treatment and tumor treating fields induced cell death in glioblastoma

Abstract

Abstract Objective: Patients suffering from Glioblastoma (GBM) usually present with perilesional edema which is the major contributor of neurologic deficit. Dexamethasone (Dex) has become the corticoid of choice due to its fast and effective alleviation of perilesional edema. The impact of concomitant Dex treatment on TTFields efficacy is unexplored to date. Methods: Human GBM cell lines MZ54 and U251 were treated with TTF in combination with Dex and the effects on cell counts and cell death were determined via flow cytometry. We furthermore investigated the influence of Dex on the cell cycle distribution/cell cycle arrest with and without double thymidine block for synchronisation via flow cytometry in both cell lines. Results: TTF treatment (200 kHz/250 kHz) for 72 h was able to induce massive cell death (70 %) in the cultures of both cell lines. Cell cycle analysis performed after synchronization showed that Dex treatment (65 µM/165 µM) evoked an accumulation of both cell lines in the G0/G1 phase. Concurrent Dex treatment had no significant influence on the extent of apoptosis induced by TTFields. Conclusions: Despite the partial G0/G1 arrest induced by Dex, our results show no interference of Dex with the antitumorous capacity of TTF in vitro. These data support the hypothesis that concomitant therapy with Dex does not negatively interfere with TTF efficacy in primary GBM. Citation Format: Abigail Schiesl, Benedikt Linder, Franz Rödel, Stephanie Hehlgans, Ömer Güllülü, Volker Seifert, Donat Koegel, Christian Senft, Daniel Dubinski. Concomitant dexamethasone treatment and tumor treating fields induced cell death in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1065.