Fig. (3).

Targeted toxins for the treatment of glioma. Human brain tumors have been shown to overexpress several receptors, including urokinase-type plasminogen activator receptor, transferring receptor, pleiotropic immunoregulatory cytokine receptors and growth factor receptors. The expression of these receptors seems to be more abundant in malignant tumors, than in benign, slow growing tumors. Since these receptors are virtually absent in the normal brain, they have been targeted in several therapeutic approaches in the treatment of glioma, to avoid toxicity to normal brain tissue. Ligands of these receptors, such as IL-13, IL-4, uPA, transferrin, EGF and TGF have been fused to the catalytic and translocation domains of highly cytotoxic bacterial products, including Pseudomonas and Diphteria toxins (T), in order to kill selectively malignant glioma cells, but preserving surrounding normal brain tissue.