title: Absolute quantification of a therapeutic domain antibody using ultra-performance liquid chromatography-mass spectrometry and immunoassay.
abstract: BACKGROUND
  Domain antibodies (dAbs; ∼10-15 kDa) are made up of the variable heavy chain or the variable light chain of the antibody structure, and retain binding capability. dAbs have proved difficult to detect in plasma using immunoassay without specific antibodies raised against the dAb.
  
  
  RESULTS
  A sensitive and selective UPLC-MS/MS method for the absolute quantification of a dAb in monkey plasma was developed (range: 1 to 500 ng/ml) without the need for a specific capture antibody. This method was used to analyze pharmacokinetic studies early on in drug development. Furthermore, an immunoassay was developed and the pharmacokinetic samples were reanalyzed.
  
  
  CONCLUSIONS
  The two assays show good correlation (r(2) = 0.92), giving confidence in using either method for quantification of the dAb.
authors.affiliation: Worldwide Bioanalysis, Drug Metabolism & Pharmacokinetics, GlaxoSmithKline, 709 Swedeland Rd, King of Prussia, PA 19406, USA. matthew.e.szapacs@gsk.com
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Szapacs
authors.forename: James J
authors.initials: JJ
authors.lastname: Urbanski
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Kehler
authors.forename: Robert
authors.initials: R
authors.lastname: Wilson
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Boram
authors.forename: Charles S
authors.initials: CS
authors.lastname: Hottenstein
authors.forename: David R
authors.initials: DR
authors.lastname: Citerone
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D007118:Immunoassay / Q000379:methods*; D007128:Immunoglobulin Fragments / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism / Q000627:therapeutic use; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology; D007275:Injections, Intravenous; D008252:Macaca fascicularis; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014357:Trypsin / Q000378:metabolism
chemical_list: D007128:Immunoglobulin Fragments; D007074:Immunoglobulin G; D014357:Trypsin