title: Integrin alphaIIbbeta3-specific synthetic human monoclonal antibodies and HCDR3 peptides that potently inhibit platelet aggregation.
abstract: The interaction of fibrinogen with integrin alphaIIbbeta3 (GPIIb/IIIa), in part mediated by an RGD tripeptide motif, is an essential step in platelet aggregation. Based on their inhibition of platelet aggregation, three integrin alphaIIbbeta3 inhibitors are clinically approved. The clinically most widely used integrin alphaIIbbeta3 inhibitor abciximab is a chimeric mouse/human antibody that induces thrombocytopenia, often severe, in 1-2% of patients due to a human anti-mouse antibody (HAMA) response. In addition, unlike other ligands mimicking small molecular drugs, abciximab cross-reacts with integrin alphavbeta3 and alphaMbeta2. Here we used phage display to select monoclonal antibodies specific to integrin alphaIIbbeta3 from a synthetic human antibody library based on the randomized HCDR3 sequence VGXXXRADXXXYAMDV. The selected antibodies revealed a strong consensus in HCDR3 (V(V/W)CRAD(K/R)RC) and high specificity toward integrin alphaIIbbeta3 but not to other RGD binding integrins such as alphavbeta3, alphavbeta5, and alpha5beta1. The selected antibodies as well as three synthetic peptides (VWCRADRRC, VWCRADKRC, and VVCRADRRC) whose sequences were derived from the HCDR3 sequences of the selected antibodies strongly inhibited the interaction between integrin alphaIIbbeta3 and fibrinogen and platelet aggregation ex vivo. To our knowledge, these are the first fully human monoclonal antibodies that are specific to integrin alphaIIbbeta3 and can potently inhibit platelet aggregation.
authors.affiliation: The Skaggs Institute for Chemical Biology and the Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: Junho
authors.initials: J
authors.lastname: Chung
authors.forename: Christoph
authors.initials: C
authors.lastname: Rader
authors.forename: Mikhail
authors.initials: M
authors.lastname: Popkov
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Hur
authors.forename: Hyun-Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Lee
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Barbas
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology*; D000918:Antibody Specificity; D022801:Complementarity Determining Regions / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology*; D004220:Disulfides / Q000378:metabolism; D005340:Fibrinogen / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D022801:Complementarity Determining Regions; D004220:Disulfides; D007140:Immunoglobulin Fab Fragments; D019151:Peptide Library; D010455:Peptides; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D005340:Fibrinogen