Figure 4. Synergy analysis of glioblastoma cell lines treated with varying concentrations of gartisertib and/or TMZ and/or RT.

(A) ZIP synergy scores were calculated for each combination as an average across all concentrations tested, with each data point representing one cell line. Combinations of gartisertib with TMZ and/or RT had significantly higher synergy scores than TMZ+RT (^**** p < 0.0001, ^*** p < 0.001, ^** p < 0.01). (B) ZIP synergy scores are shown across the various concentrations of gartisertib tested when combined with the clinically relevant doses of RT (2 Gy) and TMZ (33 μM). Asterisks denote statistically significant synergy scores compared to TMZ+RT from a one-way ANOVA (^** p < 0.01, ^* p < 0.05). Overall, gartisertib was significantly more synergistic than a clinically relevant dose of TMZ+RT when combined with TMZ and/or RT at lower gartisertib concentrations (0.039–0.156 μM). (C–E) Cell viability (mean + SEM) of all glioblastoma cell lines treated with gartisertib alone (blue) and in combination with clinically relevant doses of TMZ (33 μM) (C), RT (2 Gy) (D) or TMZ (33 μM) + RT (2 Gy) (E) (red) are depicted for each concentration of gartisertib tested. The average cell viability for single agent treatment of TMZ, RT and TMZ+RT (green) is also shown. Data points represent the mean ± SEM of synergy scores and cell viability of combined data across all 12 glioblastoma cell lines. This shows that low doses of gartisertib achieve favourable reduction in cell viability with TMZ and/or RT, while at higher doses (>2.5 μM) there is less change compared to gartisertib alone.