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Sandeep Yadav, Barthélemy Demeule, Jun Liu, Steven J Shire; The Relative Affinities of Ranibizumab and Aflibercept for Vascular Endothelial Growth Factor A (VEGF) - an Analytical Ultracentrifugation Study. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1942.
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To evaluate the relative VEGF binding affinities of ranibizumab and aflibercept in free solution using sedimentation velocity analytical ultracentrifugation in a competitive binding mode.
Analytical ultracentrifugation experiments were performed at 20°C in phosphate-buffered saline (pH 7.2, 137 mM NaCl, 27 mM KCl, 8 mM Na2HPO4 and 1.5 mM KH2PO4). Sedimentation velocity was assessed in an Optima XL-I analytical ultracentrifuge equipped with absorbance optics, interference optics (Beckman Coulter, Fullerton, CA, USA), and fluorescence optics (Aviv Biomedical). Alexa Fluor 488 protein labeling kits were purchased from Molecular Probes (Eugene, OR, USA). First, the sedimentation coefficients of VEGF, ranibizumab, aflibercept and pre-formed ranibizumab-VEGF and aflibercept-VEGF complexes were obtained; second, competition experiments were conducted by challenging the pre-formed anti-VEGF/VEGF complexes with a different VEGF inhibitor.
At equivalent molar ratio ranibizumab was able to displace aflibercept from preformed aflibercept-VEGF complexes in solution (Figure) whereas aflibercept was not able to displace ranibizumab from preformed ranibizumab-VEGF complexes.
These new data show that in solution ranibizumab is capable of displacing aflibercept from pre-formed complexes with VEGF indicating that it is very unlikely that aflibercept has 100-fold higher affinity for VEGF than ranibizumab as previously published by Papadopoulos et al. (Angiogenesis. 2012 Jun;15(2):171-85).
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