Folate Receptor Targeted Liposomes

Tumor cell targeting is a promising drug delivery strategy. Folate receptor (FR) is a cellular marker selectively overexpressed in a significant fraction of human neoplasms. Folate derivatized liposomes loaded with therapeutic agents have been shown to be efficiently taken up and to exhibit selective cytotoxicity in receptor positive tumor cells. FRtargeted liposomes have thus been evaluated for the targeted delivery of a variety of bioactive agents, including chemotherapeutic agents, antisense oligos, plasmid DNA, photosensitizers, and neutron capture agents. In addition, FRtargeted liposomal anthracyclines have been shown to overcome Pgp-mediated drug resistance in vitro and to have superior antitumor activity to non-targeted control liposomes in several preclinical murine solid tumor as well as leukemia models. Furthermore, strategies have been developed to selectively upregulate FR expression in tumor cells, which might further enhance the translational potential of this targeting strategy. The small size and presumed lack of immunogenicity of folate as a targeting ligand make these liposomes particularly attractive candidates for future clinical development.