Phenotypic knockout of VEGF-R2 and Tie-2 with an intradiabody reduces tumor growth and angiogenesisin vivo

Abstract

The endothelial cell receptor-tyrosine kinases, VEGF receptor 2 (VEGF-R2) and Tie-2, and their ligands, vascular endothelial growth factor (VEGF) and angiopoietins 1 and 2, respectively, play key roles in tumor angiogenesis. Several studies suggest that the VEGF receptor pathway and the Tie-2 pathway are independent and essential mediators of angiogenesis, leading to the hypothesis that simultaneous interference with both pathways should result in additive effects on tumor growth. In this study, a human melanoma xenograft model (M21) was used to analyze the effects of simultaneous intradiabody depletion of vascular endothelial growth receptor-R2 and Tie-2 on tumor angiogenesis and tumor xenograft growth. The intradiabodies were expressed from recombinant adenovirus delivered through subtumoral injection. Blockade of both VEGF-R2 and Tie-2 pathways simultaneously or the VEGF receptor pathway alone resulted in a significant inhibition of tumor growth and tumor angiogenesis (92.2% and 74.4%, respectively). In addition, immunohistochemical staining of intradiabody-treated tumors demonstrated a decreased number of tumor-associated blood vessels versus control treatment. Previous studies with intrabodies had demonstrated that the Tie-2 receptor pathway was essential for tumor growth. The simultaneous blockade of the VEGF and Tie-2 pathways resulted in effective inhibition of tumor growth and demonstrated the potential of simultaneous targeting of multiple pathways as a therapeutic strategy

Cotargeting of VEGFR-1 and -3 and angiopoietin receptor Tie2 reduces the growth of solid human ovarian cancer in mice

“…In a melanoma xenograft model, VEGFR-2 and Tie2 intradiabodies have reduced subcutaneous tumor growth. 38 In a prostate tumor model, combined local delivery of endostatin-angiostatin and sTie2 revealed increased treatment effect. 39 Inhibition of Tie2 has been utilized in cancer models including mammary tumors, 32 melanoma 32,40 and glioblastoma multiforme 41 and reduced tumor growth has been achieved.…”

Experimental anti‐angiogenesis causes upregulation of genes associated with poor survival in glioblastoma

“…9 Consequently, impairing two anti-angiogenic pathways at a time is more efficient than monotherapy. 10,11 Given the heterogeneous responses to anti-angiogenesis in animal models and the increasing use of anti-VEGF therapy in humans (Bevacizumab, Avastin TM ), it is important to comprehend how tumor cells react to such therapies on a molecular level. This knowledge most certainly will help to identify new ''druggable'' targets 12 for adjuvant anti-angiogenic intervention.…”

Research and development of next generation of antibody-based therapeutics

“…The most commonly used intrabodies are in the form of scFv as a single polypeptide. Other antibody formats have also been used, including Fab fragments [79] , single domain antibodies [80] , conventional IgG antibodies, and multivalent bispecific fragments (for example, "intradiabody" [81] ). Intrabodies, through the use of N-or C-terminal tags that encode natural intracellular trafficking signals, can direct the antibody-antigen interaction to a specific cellular compartment [82] .…”