Anticancer therapies have long been challenging clinically due to a lack of selectivity, specificity, bioavailability, and the presence of unwanted adverse side effects. Efforts have been in place to discover novel targets in order to develop new therapies. For instance, tumor endothelial cells (TECs) are now known to manipulate the antitumor immune surveillance by reducing the expression of adhesion molecules on the luminal surface of the microvessels. This results in a decrease in immune cell infiltration in the tumor microenvironment and, consequently, a reduction in tumor cell killing. However, the underlying molecular and cellular mechanisms of these immunosuppressive machineries remain unclear. Thus, understanding these mechanisms would aid the promising and upcoming immunotherapy strategies in targeting cancers. In this chapter, we explore how TECs in the microvasculature modulate the antitumor immune response by tumor and endothelial cell-secreted vascular endothelial growth factors, galectins, epidermal growth factor-like domain 7, and basic fibroblast growth factor.