Liposome targeting to tumors using vitamin and growth factor receptors.

Liposome-encapsulated anticancer drugs reveal their potential for increased therapeutic efficacy and decreased nonspecific toxicities due to their ability to enhance the delivery of chemotherapeutic agents to solid tumors. Advances in liposome technology have resulted in the development of ligand-targeted liposomes capable of selectively increasing the efficacy of carried agents against receptor-bearing tumor cells. Receptors for vitamins and growth factors have become attractive targets for ligand-directed liposomal therapies due to their high expression levels on various forms of cancer and their ability to internalize after binding to the liposomes conjugated to receptors' natural ligands (vitamins) or synthetic agonists (receptor-specific antibodies and synthetic peptides). This chapter summarizes various strategies and advances in targeting liposomes to vitamin and growth factor receptors in vitro and in vivo with special emphasis on two extensively studied liposome-targeting systems utilizing folate receptor and HER2/neu growth factor receptor.