Ph I Zactima + Imatinib Mesylate & Hydroxyurea for Pts w Recurrent Malignant Glioma

vascular endothelial growth factor (VEGF) angiogenic \& Phosphoinositide 3-kinase inhibitor/Protein Kinase B (PI3K/AKT) mitogenic cascades are 2 upregulated cell signalling pathways in MG that contribute to several hallmark phenotypic features of these tumors. Regimen of Zactima + imatinib mesylate represents novel anti-glioma strategy because it targets 3 key mediators of dysregulated cell signalling involving VEGF \& PI3K-AKT pathways including VEGFR, epidermal growth factor receptor (EGFR) \& platelet derived growth factor(PDGFR). Furthermore by combining Zactima w imatinib mesylate, VEGF \& PI3-k/AKT pathways can potentially inhibit multiple mediators of each of these pathways. Regarding PI3-K/AKT signalling, regimen can inhibit activation of EGFR \& PDGFR. Regarding VEGF signalling, regimen has potential to inhibit 3 components of VEGFR directed angiogenesis. 1st, Zactima can directly inhibit VEGFR activation. 2nd, both Zactima \& imatinib mesylate can indirectly decrease activity of VEGF pathway by diminishing positive input from activated PI3-K/AKT signalling. 3rd, imatinib mesylate may inhibit PDGF-regulated pericyte maturation of tumor blood vessels. We have previously demonstrated that regimen of imatinib mesylate + hydroxyurea is active regimen among recurrent glioblastoma multiforme (GBM) pts. Furthermore this activity appears substantially better than that reported for imatinib mesylate alone. Although mechanism of enhanced activity for imatinib mesylate when combo w hydroxyurea is unclear, it is logical to build upon combo of imatinib mesylate + hydroxyurea in subsequent studies rather than imatinib mesylate alone. Current study will therefore determine MTD of Zactima when combo w standard doses of imatinib mesylate \& hydroxyurea among RMG pts. Ph II study will then be performed, incorporating maximum tolerated dose (MTD) of Zactima + imatinib mesylate in order to evaluate anti-glioma potential of regimen.