Combination of metformin and PEITC. A. Combination of low doses of metformin and PEITC on CAOV3 show an improved effect on cell death after 72 hours compared to either drug individually. Combination can reduce doses necessary to achieve high levels of cell death. B. In the cisplatin resistant ovarian cancer line A2780cis, metformin and PEITC work synergistically and are more effective than cisplatin. Cell death is significantly increased when metformin and PEITC are given together. Cisplatin, even at higher doses, is unable to produce similar cell death. C. Combination index (CI) values for A2780cis calculated using CalcuSyn software. CI values below 1 are considered synergistic combinations, with greater synergy as the value approaches zero. Metformin and PEITC are synergistic at equal ratio effective doses (ED). * p < 0.01 when compared to control treatment.