Overcoming Multidrug Resistance in Cancer: An Update on the Clinical Strategy of Inhibiting P-Glycoprotein

Multidrug resistance (MDR) is a significant obstacle to providing effective chemotherapy to many patients. Multifactorial in etiology, classic MDR is associated with the overexpression of P-glycoprotein (P-gp), resulting in increased efflux of chemotherapy from cancer cells. Inhibiting P-gp as a method to reverse MDR in cancer patients has been studied extensively, but the results have generally been disappointing.

The development of P-gp inhibitors is reviewed, including a discussion of early agents that are no longer being developed and third-generation agents that are currently in clinical trials.