[Therapeutic approaches for multidrug resistance].

One of the major problems in cancer chemotherapy is the development of drug resistance during treatment. In the treatment of tumors with antitumor agents, tumor cells can acquire resistance to the drugs. This type of resistance is called as acquired drug resistance and the acquired drug resistances is a major factor for limiting the clinical use of antitumor agents. The elucidation of the resistance mechanisms has progressed well recently owing to the application of cellular and molecular techniques in addition to the usual biological and biochemical techniques. In this article, the mechanisms of cellular resistance, especially those of multidrug resistance at a molecular level, and possible approaches to overcoming drug resistance are described and discussed.