Fig. 2

Strong synergism between tamoxifen and lovastatin evident from the dual-drug assays of tamoxifen plus lovastatin on Day 2. The data from six biologic replicates are included in the calculations. a. Single agent dose-response data and fitted curve for lovastatin, calculated from the normalized cell density data recorded from Column 9 of the 96-well plate (Additional file 2: Fig. S1). In the case of lovastatin, data from 49 experiments are aggregated to generate the curve (see Methods). b. Single agent dose-response data and fitted curve for tamoxifen (N = 6), generated from normalized Column 10 data (Additional file 2: Fig. S1). The Loewe model generates the reference concentration space from the two single agent dose-response curves. c. Shown here is the experimental two-drug combination dose-response surface, expressed as a percentage of the control value, calculated from the cells-only data and normalized to a value of 1 (see Methods). The plot thus portrays the efficacy of each of the 49 dual-drug combinations. Overlain on the dose-response surface are the Loewe synergy levels depicted in (d), colored without regard to statistical significance, according to the Synergism/Antagonism scale at the right of the graph. d. Shown in matrix format are synergy scores calculated according to the Loewe additivity model from the dual-drug experimental dose-response in comparison to the reference dose-response surface. The larger numeral in each box is the synergy score; negative values indicate antagonism. The number below the synergy score is the standard deviation. Boxes are coloured green if the synergy score is not significant. The boxes coloured according to the Synergism/Antagonism scale indicate results that are statistically significant by the one-sample t-test. The degrees of significance are as follows: * p < 5 × 10–2; **p < 10–3, ***p < 10–4. The number of biologic replicates (N) is indicated at the top left of the matrix