Fighting cancer: from the bench to bedside using second generation cationic liposomal therapeutics

The use of second generation cationic liposomes to deliver cytotoxic drugs to solid tumors is a rational and promising therapeutic approach, given the natural affinity of cationic carrier molecules for the tumor microvasculature. Cationic liposomal therapeutics are effective in the treatment of cancers that are resistant to conventional chemotherapy and other treatment modalities. Researchers are now exploring novel ways to combine cationic nanosystems with other treatment approaches. For example, strategies for using cationic liposomes with hyperthermia or magnetic fields have been evaluated. Drug-loaded cationic liposomes have been documented to induce tumor vascular defects, alter vascular function and limit the growth of the primary tumors and metastasis. In this review, we discuss general features of the endothelium as a function of its tissue environment. We discuss the rationale for targeting tumor vessels over the tumor interstitial matrix, and for the development of second generation cationic lipids and liposomes for tumor vascular targeting. We evaluate the benefits of incorporating the polymer polyethylene-glycol (PEG) in conventional and cationic liposomes for nonspecific and relatively vascular-specific tumor targeting, respectively. Finally, we review preclinical and clinical investigations evaluating drug-loaded cationic liposomes in cancer treatment.