With the development of targeted therapeutics, especially for small-molecule inhibitors, it is important to understand whether the observed in vivo efficacy correlates with the modulation of desired/intended target in vivo. We have developed a small-molecule inhibitor of all three vascular endothelial growth factor (VEGF) receptors (VEGFR), platelet-derived growth factor receptor, and c-Kit tyrosine kinases, pazopanib (GW786034), which selectively inhibits VEGF-induced endothelial cell proliferation. It has good oral exposure and inhibits angiogenesis and tumor growth in mice. Because bolus administration of the compound results in large differences in C max and C trough , we investigated the effect of continuous infusion of a VEGFR inhibitor on tumor growth and angiogenesis.
Colony-stimulating-factor-1 (CSF-1) signaling through cFMS receptor kinase is increased in several diseases. To help investigate the role of cFMS kinase in disease, we identified GW2580, an orally bioavailable inhibitor of cFMS kinase. GW2580 completely inhibited human cFMS kinase in vitro at 0.06 M and was inactive against 26 other kinases. GW2580 at 1 M completely inhibited CSF-1-induced growth of mouse M-NFS-60 myeloid cells and human monocytes and completely inhibited bone degradation in cultures of human osteoclasts, rat calvaria, and rat fetal long bone. In contrast, GW2580 did not affect the growth of mouse NS0 lymphoblastoid cells, human endothelial cells, human fibroblasts, or five human tumor cell lines. GW2580 also did not affect lipopolysaccharide (LPS)-induced TNF, IL-6, and prostaglandin E2 production in freshly isolated human monocytes and mouse macrophages. After oral administration, GW2580 blocked the ability of exogenous CSF-1 to increase LPS-induced IL-6 production in mice, inhibited the growth of CSF-1-dependent M-NFS-60 tumor cells in the peritoneal cavity, and diminished the accumulation of macrophages in the peritoneal cavity after thioglycolate injection. Unexpectedly, GW2580 inhibited LPS-induced TNF production in mice, in contrast to effects on monocytes and macrophages in vitro. In conclusion, GW2580's selective inhibition of monocyte growth and bone degradation is consistent with cFMS kinase inhibition. The ability of GW2580 to chronically inhibit CSF-1 signaling through cFMS kinase in normal and tumor cells in vivo makes GW2580 a useful tool in assessing the role of cFMS kinase in normal and disease processes.CSF-1 ͉ macrophage colony-stimulating factor
Inhibition of the vascular endothelial growth factor (VEGF) signaling pathway has emerged as one of the most promising new approaches for cancer therapy. We describe herein the key steps starting from an initial screening hit leading to the discovery of pazopanib, N(4)-(2,3-dimethyl-2H-indazol-6-yl)-N(4)-methyl-N(2)-(4-methyl-3-sulfonamidophenyl)-2,4-pyrimidinediamine, a potent pan-VEGF receptor (VEGFR) inhibitor under clinical development for renal-cell cancer and other solid tumors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.