Macrophage-colony stimulating factor (M-CSF), a cytokine required for the differentiation of monocyte-lineage cells, promotes the formation of high-density vessel networks in tumors (Lin et al. 2001; 2006) and therefore

possesses therapeutic potential as a M-CSF inhibitor (Aharinejad et al. 2004; Paulus et al. 2006). However, the physiological role of M-CSF in vascular and lymphatic development, as well as the precise mechanisms underlying the anti-angiogenic effects of M-CSF inhibition, remains unclear. Moreover, therapeutic potential of M-CSF inhibition in other neovascular diseases has not yet been evaluated. In this study, we used osteopetrotic (op/op) mice to demonstrate that M-CSF deficiency reduces the abundance Nutlin-3a of LYVE-1+ and LYVE1- macrophages, resulting in defects in vascular and lymphatic development. In ischemic retinopathy, M-CSF was required for pathological neovascularization, but was not required for the recovery of normal vasculature. In mouse osteosarcoma (established from c-Myc–overexpressing, Ink4a/ARF −/−, bone marrow-derived stromal cells), M-CSF inhibition effectively suppressed tumor angiogenesis and lymphangiogenesis, and disorganized extracellular matrices. In contrast to VEGF blockade, interruption of M-CSF inhibition did

not promote rapid vascular regrowth. Continuous M-CSF inhibition did not affect healthy vascular and lymphatic systems outside tumors. These results suggest M-CSF-targeted therapy is an ideal strategy for treating ocular GSK2126458 neovascular diseases and cancer (Kubota et al. J. Exp.

Med. 2009). O178 Pre-Clinical Evaluation of a Potent and Selective CXCR4 Peptide Antagonist Currently in Phase 1 Trials for Cancer Sheng-Bin Peng 1 , Liang Zeng Yan1, Wayne Kohn1, Qinyuan Lou1, Lisa Russell1, Datian Lin1, Xiaoyi Zhang1, William Roell1, John Wijsman1, Kelly Credille1, Yu-Hua Hui1, Maciej Zamek-Gliszczynski1, Jacqueline Akunda1, John Stille1, Donald Thornton1, Jonathan Yingling1 1 Eli Lilly and Company, Indianapolis, IN, USA Emerging evidence demonstrates that SDF-1 (or CXCL12) selleck and CXCR4, a chemokine and chemokine receptor pair, play important roles in multiple stages of tumorigenesis. We have recently developed a series of potent and selective CXCR4 peptide antagonists, and one of which is currently in Phase 1 clinical trials for cancer. This peptide antagonist specifically blocks SDF-1 binding to human and monkey CXCR4 with IC50 values of 0.079 and 0.097 nM, respectively. It inhibits SDF-1-induced GTP binding with Kb value of 0.38 nM. In human lymphoma U937 cells expressing endogenous CXCR4, the peptide inhibits SDF-1-induced cell migration with IC50 value of 0.26 nM. It also inhibits SDF-1/CXCR4-mediated intracellular signaling, exhibiting a dose-dependent inhibition of SDF-1-stimulated pERK and pAkt in multiple tumor cell lines.