2.8. Synergy Score Calculation

The fluorescence measurement data were also visualized and analyzed using freely available software, Combenefit (version 2.021, Cancer Research UK Cambridge Institute, Cambridge, UK), which simultaneously assesses synergy/antagonism from dose-response data using three classical models, namely the Loewe, the Bliss, and the Highest Single Agent (HAS). In this study, we applied the Loewe additivity theory for two-drug combinations. The analysis was performed as described by Di veroli et al. [39]. Briefly, the data were expressed as a “percentage of control” and saved in .xls files according to a template provided by the software developers. The difference between the Loewe model-based expected additive effect and the actual effect of the drug combination was calculated by the software. This difference value is called a synergy score. The software calculates a synergy score for each combination, where a positive score indicates synergy, a score of 0 is additive, and a negative score indicates antagonism [39]. The calculated values were represented as a synergy heatmap with the color scale from blue (synergism) to red (antagonism).