Analysis of combined drug effects of combination treatments. Cells treated with different doses of A. docetaxel and/or carboplatin, B. PNP-GDEPT (Fludara (1 μg/mL (2.7 μM)) and/or docetaxel, C. PNP-GDEPT and/or carboplatin D. PNP-GDEPT (Fludara (1 μg/mL (2.7 μM)) and/or docetaxel and/or carboplatin were analysed for cell viability using WST-1 assay on day 5. Graphs representing inhibition of cell growth plotted as a function of increasing doses of docetaxel and/or carboplatin and/or PNP-GDEPT for OVCAR-3 cells are shown in Additional file 7 (Figure A2). Values represent mean (± SEM) of three independent experiments. Based on these, Combination Indices (CIs) for different combinations against the fraction affected (Fa) were plotted to generate CI/Fa plots using Chou and Talalay's statistical software (CalcuSyn). Data for OVCAR-3 cells are shown. Similar data were obtained for SKOV-3 cells. Synergy is indicated at CI values of < 0.90, Additive interaction is indicated at CI values of 0.90-1.10 and antagonism at CI values of > 1.10.