title: Development and validation of receptor occupancy pharmacodynamic assays used in the clinical development of the monoclonal antibody vedolizumab.
abstract: BACKGROUND
  Vedolizumab is a monoclonal antibody approved for use in ulcerative colitis and Crohn's disease. By specifically binding to α4 β7 integrin, vedolizumab prevents trafficking of lymphocytes to the gut, thereby interfering with disease pathology. During the clinical development program, the pharmacodynamic effect of vedolizumab was evaluated by 2 flow cytometry receptor occupancy assays: act-1 (ACT-1) and mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Here we describe the development and validation of these assays.
  
  
  METHODS
  The ACT-1 assay is a receptor occupancy free-site assay that uses a monoclonal antibody with the same binding epitope as vedolizumab to detect free (unbound) sites on α4 β7 integrin. The MAdCAM-1 assay used a soluble version of the natural ligand for α4 β7 integrin to detect free sites. The assays were validated using a fit-for-purpose approach throughout the clinical development of vedolizumab.
  
  
  RESULTS
  Both the ACT-1 assay and the MAdCAM-1 assay demonstrated acceptable reproducibility and repeatability. The assays were sufficiently stable to allow for clinical use. During clinical testing the assays demonstrated that vedolizumab was able to saturate peripheral cells at all doses tested.
  
  
  CONCLUSIONS
  Two pharmacodynamic receptor occupancy assays were developed and validated to assess the effect of vedolizumab on peripheral blood cells. The results of these assays demonstrated the practical use of flow cytometry to examine pharmacodynamic response in clinical trials.
authors.affiliation: Takeda Pharmaceuticals International Company, Cambridge, Massachusetts.
authors.forename: Tim
authors.initials: T
authors.lastname: Wyant
authors.affiliation: Takeda Pharmaceuticals International Company, Cambridge, Massachusetts.
authors.forename: Jose
authors.initials: J
authors.lastname: Estevam
authors.affiliation: Takeda Pharmaceuticals International Company, Cambridge, Massachusetts.
authors.forename: Lili
authors.initials: L
authors.lastname: Yang
authors.affiliation: Takeda Pharmaceuticals International Company, Cambridge, Massachusetts.
authors.forename: Maria
authors.initials: M
authors.lastname: Rosario
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000276:immunology; D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D002448:Cell Adhesion / Q000276:immunology; D015815:Cell Adhesion Molecules; D003093:Colitis, Ulcerative / Q000097:blood / Q000188:drug therapy* / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007136:Immunoglobulins / Q000097:blood / Q000276:immunology / Q000302:isolation & purification*; D016023:Integrins / Q000276:immunology / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology; D009088:Mucoproteins / Q000097:blood / Q000276:immunology / Q000302:isolation & purification*; D010361:Patients; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000097:blood / Q000276:immunology / Q000302:isolation & purification*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D015415:Biomarkers; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D016023:Integrins; C504265:MADCAM1 protein, human; D009088:Mucoproteins; C414202:TRAF3IP2 protein, human; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; C071777:integrin alpha4beta7; C543529:vedolizumab
keywords: MADCAM-1ACT-1; crohn's disease; pharmacodynamics; ulcerative colitis; vedolizumab