Liposomal technology in cancer therapy

The current status of liposomal technology in cancer therapy was described in this review. The newly developed polyethyleneglycol coated liposomes (PEG-liposomes) have demonstrated considerable potential as a carrier for the delivery of drugs in cancer therapy. It has been shown that PEG-liposomes are not readily taken up by the macrophages in the reticuloendothelial system (RES) but also stay in the circulation for a relatively long period of time. Elevated liposomal accumulation to the solid tumor has been shown after injection of PEG-liposomes. Small PEG-liposomes are able to traverse the endothelium of blood vessels in solid tumor and extravasate into interstitial spaces. Results from clinical studies with DOXIL® (PEG-liposomes encapsulating doxorubicin) in AIDS-related Kaposi's sarcoma revealed an increased therapeutic efficacy compared to free-drugs. Combined treatments with the thermosensitive PEG-liposomes and local hyperthermia were able to deliver the anti-cancer drug with high concentration to the tumor site. Pendant type PEG-liposomes (Fab'-PEG- immunoliposomes and transferrin-PEG-liposomes) were newly designed to gain circulate long enough to extravasate and bind the cell surface to the targeted solid tumor in vivo. Such liposomal formulations should be useful for endocytotic internalization of plasmid DNA and other bioactive materials.