Liposomes and Polymers in Folate-Targeted Cancer Therapeutics

In this chapter, we will address the therapeutic potential of targeting liposomes and polymers to the folate receptor for delivery of anticancer drugs and review the experimental data in this field. By exploiting the pharmacologic attributes of liposomes and polymers together with their cellular internalization by folate receptor-mediated endocytosis, these systems should allow for improved selectivity and control of drug delivery to folate receptor expressing cancers. Particularly, extension of circulation time and enhanced deposition in tumors coupled with reduced toxicity of liposome- and polymer-associated drugs are important assets of the nanomedicine platform when compared to free drugs or low-molecular weight conjugates. In addition, the high drug:ligand ratio of liposomes and some polymers enable the delivery of a high drug payload per ligand–receptor interaction. However these systems have also some in vivo limitations that will be discussed. It remains unclear whether folate-targeted nanomedicines can provide a significant added value in clinical applications vis-à-vis folate-targeted drug conjugates.