Synergistic Therapeutic Effects of Cimetidine/Famotidine in Combination with Doxorubicin on Cancer Cell Lines

Combination therapy in cancer is a promising approach to increase efficacy and tolerability and to decrease adverse effects and drug resistance. Recently, anti-cancer properties of H2-receptor antagonists have been reported in several pre-clinical and clinical studies. The aim of this study was to examine the effect of cimetidine and famotidine H2-blockers on cytotoxicity of doxorubicin (DOX) on A549, MCF-7, and HT-29 human cancer cell lines. The cytotoxicity of cimetidine and famotidine, alone and in combination with DOX, was determined using MTT assay after 24 h incubation. Co-administration of H2-blockers with DOX led to an increase in cytotoxicity of the cell lines studied. While DOX at 1 μM could not reduce the viability of the cultured cells below 50%, its use in combination with cimetidine or famotidine at 25 μM reduced the percentage of viable cells below 50%. Combination of cimetidine/famotidine with DOX could be a potential candidate for chemotherapy.