New non-cytotoxic taxanes synthesized from 1Odeacetylbaccatin III and special hydrophobic acylating
agents show remarkable MDR reversal activity (<99.8%) against drug-resistant human breast cancer cells when
co-administered with paclitaxel or doxorubicin. This activity is ascribed to the highly efficient blocking of
p-glycoprotein efflux by these new taxanes.