P10.30.B COMBINATION TREATMENT WITH ERIBULIN AND TTFIELDS INDUCES APOPTOSIS AND G2/M CELL CYCLE ARREST IN HUMAN GLIOBLASTOMA CELLS

Abstract BACKGROUND TTFields has emerged to a first line treatment in newly diagnosed glioblastoma (GBM) patients. Several preclinical studies showed that the alternating electric fields inhibit proliferation and survival of human glioblastoma cells by disruption of the spindle apparatus and impairment of mitotic segregation. Eribulin is an antimitotic drug, that is currently used in the third line treatment of breast cancer. As it is also able to inhibit the pro-mitotic function of TERT, which is mutated in 80% of human glioblastoma, the drug was also shown to have a radiosensitizing and antiproliferative effect on human glioblastoma and ovarian cancer cell lines. This study aims to evaluate the effect of the combination of Eribulin and TTFields on the survival and cell cycle of glioblastoma cells. MATERIAL AND METHODS U87, A172 and four patient derived glioblastoma cell lines were cultured and plated to 80% confluence. Cells were then treated with TTFields at a frequency of 200kHz for 24 hours and/or received the ED50 and 0.5-fold ED50 of Eribulin. Controls remained untreated respectively. After 24 hours cells were harvested and counted by automatic cell count. Survival and cell cycle status were evaluated by FACS analysis. RESULTS The rate of early apoptotic cells was 82.28% in the group treated with TTFields and Eribulin. With TTFields treatment only 50.99% and with Eribulin alone 14.38% of cells were in an early apoptotic state. Untreated control cells had an apoptosis rate of 4.25%. The combination of TTFields and Eribulin was significantly more effective than the single treatment modalities (p>0.05). Treatment with TTFields increased the rate of cells an G2/M status. This effect was even stronger in the group with combination treatment. CONCLUSION Combination treatment of the antimitotic drug Eribulin with TTFields is able to improve the inhibitory effect of the drugs on cell survival. Furthermore the combination therapy effects the cell cycle of glioblastoma cells inducing G2/M arrest. Future preclinical studies should focus on the antimitotic effect and the influence of the treatment on genome integrity for a more detailed insight into the mechanisms of action.