ABSTRACT
This review focuses on cationic liposomes and lipid complexes as neovascular targeting agents or so-called vascular-disrupting agents (VDAs) (1) for tumor treatment. Attacking the already established tumor blood vessel system with VDAs is an emerging concept in the treatment of cancer. In contrast to conventional chemotherapy, which targets the tumor tissue compartment, the VDA action is directed against the endothelial cells lining the newly formed tumor vasculature. Destruction of the tumor endothelial cells should ultimately lead to thrombus formation with subsequent occlusion of the tumor blood vessels. The following reduction or even collapse of tumor blood flow may cause a reduction or complete remission of the tumor cell mass (2). Both the vascular-disrupting approach and the antiangiogenic therapy are antivascular treatments, but there are important conceptional differences between the respective drug classes. VDAs target the existing tumor vasculature, thereby allowing the treatment of already established tumors. Inhibitors of angiogenesis interfere with the formation of new blood vessels and should prevent further tumor growth. Although new reports show that antiangiogenic agents do more than merely stop growth of new blood vessels (3-5), the key differences between the two antivascular treatment strategies still remain substantial.
