Immunotherapy targeting the Wilms tumor 1 (WT1) gene product is a promising treatment modality for patients with malignant gliomas, and there have been reports of encouraging results.
Bioinformatics analysis emphasized key roles of integrin β3, hypoxia and vitronectin and their strong correlations with EGFRvIII expression in malignant glioma patient samples in vivo.
These results suggest that glioma cells themselves express Ang2 and that expression may be induced by hypoxic stimulation and may play a crucial role in the vessel maturation, angiogenesis, and vessel regression in malignant glioma.
Modulated expression patterns of vimentin and RhoA GTPase indicate a potentially increasing grade of malignancy in treated cell fractions correlating well with extremely aggressive tumour phenotypes observed clinically at recidivation of treated malignant gliomas.
In this study, we demonstrate the feasibility of combining adenovirus-mediated soluble VEGF receptor-1 anti-angiogenic gene therapy with AdHSV-tk/GCV suicide gene therapy to treat experimental MGs.
Using DNA microarray analysis, we examined VEGF and related gene expression in 71 newly diagnosed malignant gliomas and analyzed the relationship to edema and survival.
Several antiangiogenic drugs targeting vascular endothelial growth factor (VEGF) or its receptors are currently in clinical trials as therapy for high-grade glioma and bevacizumab was recently approved by the FDA for treatment of recurrent glioblastoma.
In conclusion, p38 MAPK and JNK pathways play an important role in VEGF secretion from malignant glioma cells under normoxic conditions, possibly contributing to VEGF-induced angiogenesis in malignant gliomas at vital tumor areas where there is no hypoxia.
Statistical analysis revealed that the Ang2 expression was negatively correlated with vessel maturation in malignant gliomas and that vascular endothelial growth factor expression was positively correlated with vessel maturation in low-grade gliomas (P < 0.05).
Antiangiogenesis with bevacizumab, an antibody against vascular endothelial growth factor (VEGF), has been used for devascularization to limit the growth of malignant glioma.
We found that these tumors expressed significant amounts of VEGF mRNA in comparison with other brain tumors, including malignant gliomas and meningiomas.
Based on these results, we performed three different antiangiogenic experiments targeted to inhibit VEGF expression in a human malignant glioma (U87) mouse model: anti-VEGF neutralized antibody intraperitoneal injection; interferon-beta intramusclar injection; and transfection of an endogenous nonspecific angiogenesis inhibitor, thrombospondin-1, into glioma cells caused inhibition of VEGF secretion and/or mRNA expression and resulted in glioma growth inhibition of 70%, 84%, and 50%, respectively, compared with control.
Determining the mechanism of treatment failure of the VEGF monoclonal antibody bevacizumab for malignant glioma would provide insight into approaches to overcome therapeutic resistance.