MS-073, also known as CP-162398, is a P-glycoprotein inhibitor (P-gp). MS-073 was compared with verapamil with regard to its ability to overcome MDR in vitro and in vivo. MS-073 at 0.1 microM almost completely reversed in vitro resistance to vincristine (VCR) in VCR-resistant P388 cells. MS-073 also reversed in vitro VCR, adriamycin (ADM), etoposide, and actinomycin D resistance in ADM-resistant human myelogenous leukemia K562 (K562/ADM) cells, MS-073 reverses MDR by competitively inhibiting drug binding to P-glycoprotein.
