title: Active immunization against the vascular endothelial growth factor receptor flk1 inhibits tumor angiogenesis and metastasis.
abstract: The vascular endothelial growth factor (VEGF) receptor fetal liver kinase 1 (flk1; VEGFR-2, KDR) is an endothelial cell-specific receptor tyrosine kinase that mediates physiological and pathological angiogenesis. We hypothesized that an active immunotherapy approach targeting flk1 may inhibit tumor angiogenesis and metastasis. To test this hypothesis, we first evaluated whether immune responses to flk1 could be elicited in mice by immunization with dendritic cells pulsed with a soluble flk1 protein (DC-flk1). This immunization generated flk1-specific neutralizing antibody and CD8+ cytotoxic T cell responses, breaking tolerance to self-flk1 antigen. Tumor-induced angiogenesis was suppressed in immunized mice as measured in an alginate bead assay. Development of pulmonary metastases was strongly inhibited in DC-flk1-immunized mice challenged with B16 melanoma or Lewis lung carcinoma cells. DC-flk1 immunization also significantly prolonged the survival of mice challenged with Lewis lung tumors. Thus, an active immunization strategy that targets an angiogenesis-related antigen on endothelium can inhibit angiogenesis and may be a useful approach for treating angiogenesis-related diseases.
authors.affiliation: ImClone Systems Incorporated, New York, NY 10014, USA. yiwen@imclone.com
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Li
authors.forename: Mei-Nai
authors.initials: MN
authors.lastname: Wang
authors.forename: Hongli
authors.initials: H
authors.lastname: Li
authors.forename: Karen D
authors.initials: KD
authors.lastname: King
authors.forename: Rajiv
authors.initials: R
authors.lastname: Bassi
authors.forename: Haijun
authors.initials: H
authors.lastname: Sun
authors.forename: Angel
authors.initials: A
authors.lastname: Santiago
authors.forename: Andrea T
authors.initials: AT
authors.lastname: Hooper
authors.forename: Peter
authors.initials: P
authors.lastname: Bohlen
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hicklin
mesh_terms: D000818:Animals; D018827:Carcinoma, Lewis Lung / Q000098:blood supply* / Q000473:pathology; D005260:Female; D007167:Immunotherapy; D008546:Melanoma, Experimental / Q000098:blood supply* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009362:Neoplasm Metastasis / Q000517:prevention & control*; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology*; D017978:Receptors, Growth Factor / Q000276:immunology*; D040262:Receptors, Vascular Endothelial Growth Factor
chemical_list: D017978:Receptors, Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor