Ranibizumab inhibits multiple forms of biologically active vascular endothelial growth factor in vitro and in vivo

Neovascularage-related macular degeneration (AMD) is the leading cause of blindness in older adults in the Western world. Ranibizumab(Lucentis®), a humanized antibodyfragment directed against vascular endothelial growth factor (VEGF-A), was recently approved by the US Food and Drug Administration (FDA) for the treatment of neovascularAMD. The objective of this study was to characterize the binding affinity and pharmacological activity of ranibizumabfor 3 biologically activeforms of VEGF-A: VEGF165, VEGF121, and VEGF110. The apparent equilibrium binding affinity of ranibizumabfor VEGF-A molecules was determined by Biacore® analysis; the biological activityof VEGF-A was demonstrated in a human umbilical vein endothelial cell (HUVEC) proliferation–inhibition assay. Inhibition of VEGF-A-induced vascular permeabilityby ranibizumabwas assessed in vivo using hairlessguinea pigs and a modified Miles assay. Ranibizumabwas capable of binding to recombinant human VEGF165, VEGF121, and VEGF110 (KD ≤ 192 pM), inhibiting VEGF-A-induced HUVEC proliferation in a concentration-dependent manner. Ranibizumabalso exerted potent dose-dependent inhibition (IC50 of 0.4–1.2 nM) of the vascular permeability-enhancing activity of VEGF165, VEGF121, and VEGF110 in the Miles assay. In conclusion, these results show that ranibizumabis capable of binding to and specifically inhibiting the activities of 3 biologically activeforms of VEGF-A. As VEGF-A plays a pivotal role in the pathogenesis of neovascularAMD, ranibizumabactivity, as demonstrated in this study, supports its clinical utility in the treatment of this disease.