Vascular Normalization as an Emerging Strategy to Enhance Cancer Immunotherapy

The recent approval of Provenge has brought new hope for anticancer vaccine therapies. However, the immunosuppressive tumor microenvironment seems to impair the efficacy of vaccine therapies. The abnormal tumor vasculature creates a hypoxic microenvironment that polarizes inflammatory cells toward immune suppression. Moreover, tumors systemically alter immune cells' proliferation, differentiation, and function via secretion of growth factors and cytokines. For example, VEGF, a major proangiogenic cytokine induced by hypoxia, plays a critical role in immunosuppression via these mechanisms. Hence, antiangiogenic treatment may be an effective modality to potentiate immunotherapy. Here, we discuss the local and…