Abstract
The various mechanism of anticancer drug resistance is well known. Currently published data, however, do not yet show that MDR reversal agents will be useful clinically. In the present study, polymer micelle-based or immunoliposome-based drug delivery system also could not overcome multidrug-resistance. There is a natural drug resistance in solid tumors in terms of drug delivery: sufficient drug delivery can not be achieved in cancers having very few tumor vessels and an abundant collagen-rich interstitium. Such cancers include scinhous stomach cancer, inflammatory breast cancer, and pancreatic cancer. It is described how to cope with the natural drug resistance in this paper.
