The LM609 antibody specifically recognizes α <sub>V </sub>β <sub>3 </sub> integrin and inhibits angiogenesis, bone resorption, and viral infections in an arginine-glycine-aspartate-independent manner. LM609 entered phase II clinical trials for the tr ...
The LM609 antibody specifically recognizes α V β 3 integrin and inhibits angiogenesis, bone resorption, and viral infections in an arginine-glycine-aspartate-independent manner. LM609 entered phase II clinical trials for the treatment of several cancers and was also used for α V β 3 -targeted radioimmunotherapy. To elucidate the mechanisms of recognition and inhibition of α V β 3 integrin, we solved the structure of the LM609 antigen-binding fragment by X-ray crystallography and determined its binding affinity for α V β 3 . Using single-particle electron microscopy, we show that LM609 binds at the interface between the β-propeller domain of the α V chain and the βI domain of the β 3 chain, near the RGD-binding site, of all observed integrin conformational states. Integrating these data with fluorescence size-exclusion chromatography, we demonstrate that LM609 sterically hinders access of large ligands to the RGD-binding pocket, without obstructing it. This work provides a structural framework to expedite future efforts utilizing LM609 as a diagnostic or therapeutic tool.
Organizational Affiliation:
Unité de Virologie Structurale, Institut Pasteur, Paris, France; CNRS UMR 3569 Virologie, Paris, France. Electronic address: marija@pasteur.fr.,Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.,Department of Hematology and Oncology, University of California at San Diego, La Jolla, CA 92093-0726, USA.,Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.,Unité de Virologie Structurale, Institut Pasteur, Paris, France; CNRS UMR 3569 Virologie, Paris, France.,Department of Biochemistry, University of Washington, Seattle, WA 98195, USA. Electronic address: dveesler@uw.edu.
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