Challenges in development of targeted liposomal therapeutics.

Liposomes, phospholipid vesicles with a bilayered membrane structure, have been widely used as pharmaceutical carriers for drugs and genes, in particular for treatment of cancer. To enhance the efficacy of the liposomal drugs, drug-loaded liposomes are targeted to the tumors by means of passive (enhanced permeability and retention mediated) targeting, based on the longevity of liposomes in blood and its accumulation in pathological sites with compromised vasculature, and active targeting, based on the attachment of specific ligands to the liposomal surface to bind certain antigens on the target cells. Antibody-targeted liposomes loaded with anticancer drugs demonstrate high potential for clinical applications. This review highlights evolution of liposomes for both passive and active targeting and challenges in development of targeted liposomal therapeutics specifically antibody-targeted liposomes.