Effect of docetaxel with cisplatin or vinorelbine on lung cancer cell lines

Docetaxel shows substantial activity against lung cancer. To find the optimal drug combination for docetaxel, we evaluated the effects of cisplatin, etoposide, mitomycin C, irinotecan, vindesine, and vinorelbine using three human lung cancer cell lines, ABC-1, EBC-1, and SBC-3. Drug cytotoxicity was determined by MTT assay. Tumor cells were incubated for 96 hours in the presence of docetaxel and each of the test drugs stated above. The combined drug interaction was evaluated by median-effect plot analysis and improved IC50-isobologram analysis. Both methods showed strong antagonism (subadditive or protective effect) between docetaxel and etoposide when tested on ABC-1 and EBC-1 cells. Docetaxel and cisplatin displayed additive effects on all cell lines tested, when evaluated by improved IC50-isobologram analysis. The combination of docetaxel and vinorelbine exerted synergistic effect on the growth inhibition of SBC-3 cells, which showed a wide range of fractional cytotoxicity when analyzed by median-effect plot and supraadditive when analyzed by improved IC50-isobologram. These observations suggest a possibility that docetaxel can be used in combination with vinorelbine or cisplatin in the treatment of lung cancer.