Tumor-associated macrophages and vascular endothelial growth factor in the tumor microenvironment

The tumor microenvironment is highly complex and incompletely-understood. Immune cells, including macrophages, play a key role in this environment. Macrophages often are polarized towards a tumor-supporting phenotype, suppressing a robust anti-tumor immune response. There is evidence to suggest that vascular endothelial growth factor, which normally supports angiogenesis, may be involved in this polarization of macrophages, as well as in creation of an ineffective tumor vascular structure that increases hypoxia and further discourages immune responses to the tumor. Therapies targeting VEGF have the potential to be a part of combination immunotherapies designed to shape a strong antitumor immune response by changing the polarization of macrophages and recruitment of vital immune cell types to the tumor microenvironment