Receptor-Mediated Drug Delivery

The development of receptor-targeted therapeutic agents has been initiated primarily to limit the distribution of toxic drugs to only the pathologic cells, thus minimizing collateral damage to normal cells. Receptor-mediated drug delivery can also enable otherwise membrane-impermeable drugs to enter target cells by receptor-mediated endocytosis, or it can induce desirable changes in cell behavior by activating a receptor's normal signaling pathway. This chapter begins by summarizing the basic characteristics of the receptor-mediated endocytosis process. It then elaborates on two important characteristics for selection of a receptor for drug delivery: receptor specificity and internalization/recycling. While the ligand, linker, and drug can all take on a diversity of sizes, shapes, and chemistries, a few fundamental principles can be followed to enhance therapeutic efficacy. The chapter describes the preferred characteristics of both the ligand and the drug. It also illustrates the techniques of folate-targeted drug delivery, folate-targeted radiodiagnostic imaging, chemotherapy, and immunotherapy.