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Table 2 Tumor endothelial cell antigens investigated as targets of ValloVax™

From: Safety of targeting tumor endothelial cell antigens

Tumor endothelial target protein Role of antigen in tumor angiogenesis Refs.
Vascular endothelial growth factor receptor-1 (VEGFR-1); fms-like tyrosine kinase (flt)-1 Receptor that binds VEGF with high affinity
Dominant receptor in the tumor microenvironment that is required for endothelial cell survival
[70, 71]
Vascular endothelial growth factor receptor-2 (VEGFR2); Flk-1, KDR Also known as FLK-1 and KDR
Binds to VEGF and is considered the most important receptor with regard to tumor angiogenesis
Expressed on proliferating endothelium
Low expression on healthy vascular endothelium
[62, 72]
Endoglin/CD105 Selectively expressed by endothelial cells undergoing vasculogenesis, angiogenesis, and inflammation
Promotes endothelial cell proliferation, migration, and tube formation during early development and in tumors
Fibroblast growth factor receptor (FGFR) Bind to fibroblast growth factor family members, having diverse roles in organogenesis, proliferation, pro-survival cell signaling and cellular migration
FGF/FGFR system contributes to both adult angiogenesis and tumor angiogenesis
FGFR signaling is implicated in escape of tumor vasculature from VEGF inhibitor treatment
[61, 7982]
Integrin αvβ3; CD51/CD61 An extracellular matrix adhesion receptor that coordinates endothelial cell responses during angiogenesis
Expressed in neo-angiogenic vessels; therefore, it is upregulated in the vasculature of solid tumors, while expression is low in quiescent vasculature
Tumor endothelial marker 1 (TEM1); endosialin or CD248 One of the most abundantly expressed proteins on tumor vasculature and tumor stroma of human tumors
Expression is variable among tumor types; however, this protein can reportedly be expressed on endothelial cells, pericytes, and/or fibroblasts of human and animal tumors
[67, 8893]