ABSTRACT
CVX-22 is a CovX-Body, produced by covalently attaching a thrombospondin-1 (TSP-1) type 1 repeat peptide mimetic to a humanized IgG1 molecule. To dissect the antiangiogenic mechanism of CVX-22, the numbers and proliferative status of defined tumor endothelial cell (TEC) subsets from the B16 and C32 melanoma models were examined. CVX-22 treatment reduced the numbers of activated, vascular endothelial growth factor receptor 2 (VEGFR2)-positive TECs. Because the vast majority of mitotically active TECs reside in the VEGFR2 subset, a reduction in numbers of this compartment resulted in an 82% overall decrease in BrdU labeling of TEC. However, the rate of proliferation and VEGFR2 receptor density of this VEGFR2-positive subpopulation were unaffected. Instead, CVX-22 induced endothelial cell apoptosis both in vitro and in vivo, indicating that CVX-22 acts by selective deletion of activated, VEGFR2-positive TEC. The overrepresentation of activated cells in sites of tumor angiogenesis may confer a unique specificity of CVX-22 for tumor vasculature.
Subject(s)
Cell Proliferation , Endothelium, Vascular/drug effects , Immunoglobulin G/metabolism , Melanoma, Experimental/blood supply , Neovascularization, Pathologic , Peptide Fragments/therapeutic use , Thrombospondin 1/therapeutic use , Animals , Apoptosis , Dose-Response Relationship, Drug , Endothelium, Vascular/pathology , Female , Flow Cytometry , Immunoglobulin G/immunology , Melanoma, Experimental/metabolism , Melanoma, Experimental/prevention & control , Mice , Mice, Inbred C57BL , Mice, Nude , Molecular Mimicry , Peptide Fragments/pharmacokinetics , Thrombospondin 1/pharmacokinetics , Tissue Distribution , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Vascular Endothelial Growth Factor Receptor-2/immunology , Vascular Endothelial Growth Factor Receptor-2/metabolismABSTRACT
Aryl sulfonamide-based endothelin antagonists were synthesized and covalently linked to the reactive lysine of the m38C2 antibody to create a series of CovX-Bodies. These chemically programmed antibodies behaved as potent endothelin receptor antagonists in vitro and had antitumor efficacy in a prostate cancer xenograft model which, on a molar basis, far exceeded the activity of the parent small molecule.
