Dofequidar is primarily used as a multidrug resistance (MDR) reversal agent in cancer therapy. It works by inhibiting drug efflux pumps, such as P-glycoprotein, which are often overexpressed in cancer cells. This inhibition helps to enhance the intracellular concentration of chemotherapeutic agents, making the cancer cells more susceptible to treatment. It is particularly useful in cases where tumors have developed resistance to standard chemotherapy drugs. Dofequidar is often studied in combination with other anticancer drugs to improve their efficacy and overcome resistance mechanisms. Its application is significant in improving outcomes for patients with drug-resistant cancers.