Solid Tumors: a Review

The therapeutics of tumor is largely confined upon directly encountering the tumor cells. The current cytostatic agents mainly interfere with processes involved in cell growth while the aim in immunotherapy is to make immune effector cells to selectively attack the tumor cells. A recent approach to fight tumor is to impede and interfere with its blood supply, i.e., turning off angiogenesis or neovascularisation. Drug delivery systems including polymeric carriers and colloidal carriers like liposomes, immunoliposomes, microspheres, nanoparticles are often directed against epitopes present on tumor cells and/or receptors expressed on tumor cells and carry drugs which interfere with tumor growth. In all cases, the bioactive has to cross the tumour blood vessel wall consisting of endothelial cells and basement membrane. Especially in drug delivery strategies in which polymeric, macromolecular or particulate carriers are used to increase treatment selectively, the endothelial barriers form a major obstacle.