[Overcoming of multidrug resistance by a newly synthesized quinoline compound, MS-209].

The emergence of multidrug resistance(MDR) is a major problem in cancer chemotherapy. Many compounds are developed to reverse MDR, and some of them are under clinical trials. Among them, MS-209, a novel quinoline derivative, is one of the most potent MDR reversing agents. MS-209 at 3 microM effectively reverses MDR in various cell lines in vitro. MS-209 directly interacts with P-glycoprotein and inhibits the P-glycoprotein-mediated drug transport. Oral administration of MS-209 combined with anticancer drugs markedly increases the life span of mice bearing MDR tumor cells without causing serious side effects. Thus, MS-209 is an orally active and potent MDR reversing drug without serious side effects.