[Drug-carrier complex in targeted cancer chemotherapy]

To achieve the targeting of anticancer drugs, a variety of drug-carrier complexes such as conjugates with macromolecules, particulates or oils has been widely investigated, experimentally or clinically. These are classified into 1) topical (intratumoral and intracavital) use, 2) systemic (intravenous and per oral) use, and 3) intra-arterial (chemoembolization) use. A drug delivery system (DDS) should be designed for the complex or the drug itself to accumulate at target areas (1st-order targeting), to be directed to tumor cells (2nd-order targeting), and finally to be incorporated by tumor cells (3rd-order targeting). The first order targeting will be the gateway to targeted therapy. Our experiences in 759 patients treated with arterial chemoembolization by microencapsulated drugs showed the benefits of this prototype of first-order drug targeting, in terms of enhanced drug effects with decreased drug toxicity and improved survival in combination with surgical or systemic treatments. Further studies on DDS contributed by pharmaceutical science and biophysiology will establish the place of targeted chemotherapy, for a definite improvement in the low therapeutic index of anticancer drugs.