COMP-15. META-ANALYSIS OF CANCER CELL LINES BASED ON THEIR RESPONSE TO TUMOR TREATING FIELDS (TTFIELDS)

Abstract

Tumor Treating Fields (TTFields) therapy (low intensity, intermediate frequency (100–300 kHz alternating electric fields) is an approved modality for the treatment of glioblastoma. TTFields were shown to exert an inhibitory effect on numerous cancer cell lines with some variability in the response of different cell lines. The goal of the present study is to compare characteristics of cell lines based on their response pattern to TTFields. Forty different human cancerous cell lines were treated for 72 hours with TTFields at optimal cell-specific frequency at the same nominal intensity (1.7 V/cm). Cell survival and clonogenicity were determined. Functional analysis of differentially expressed genes and mutations associated with response to TTFields was performed based on the Cancer Cell Line Encyclopedia (CCLE) database. Sensitivity to TTFields was compared with pharmacological profiling (CCLE). TTFields application demonstrated varying degree of cytotoxic effect in all cell lines tested. The inhibitory response to TTFields was found to be distributed around an average of 50% with a cytotoxic effects ranging between 14% and 86% reductions in cell counts, and a clonogenic effect ranging between no effect and 88% reduction in the number of colonies. Pharmacological profiling based on IC50 values, revealed increased sensitivity to: Lapatinib, PHA-665752 and PLX-4720 within the group of cell lines which were less sensitive to TTFields. Functional analysis of cell line gene expression and mutation data revealed enriched pathways related to DNA damage repair response, cell migration, hypoxia signaling and oxidative stress. This meta-analysis of cancerous cell line response to TTFields demonstrates the broad effectiveness of TTFields in various cell lines and define the optimal frequency to be applied for each. The data presented in this work suggest that beside their anti-mitotic properties, TTFields may have effects on other cellular pathways. Pharmacological profiling may offer a rational for combining specific agents with TTFields.