title: Using Mass Spectrometry to Quantify Rituximab and Perform Individualized Immunoglobulin Phenotyping in ANCA-Associated Vasculitis.
abstract: Therapeutic monoclonal immunoglobulins (mAbs) are used to treat patients with a wide range of disorders including autoimmune diseases. As pharmaceutical companies bring more fully humanized therapeutic mAb drugs to the healthcare market analytical platforms that perform therapeutic drug monitoring (TDM) without relying on mAb specific reagents will be needed. In this study we demonstrate that liquid-chromatography-mass spectrometry (LC-MS) can be used to perform TDM of mAbs in the same manner as smaller nonbiologic drugs. The assay uses commercially available reagents combined with heavy and light chain disulfide bond reduction followed by light chain analysis by microflow-LC-electrospray ionization-quadrupole-time-of-flight mass spectrometry (ESI-Q-TOF MS). Quantification is performed using the peak areas from multiply charged mAb light chain ions using an in-house developed software package developed for TDM of mAbs. The data presented here demonstrate the ability of an LC-MS assay to quantify a therapeutic mAb in a large cohort of patients in a clinical trial. The ability to quantify any mAb in serum via the reduced light chain without the need for reagents specific for each mAb demonstrates the unique capabilities of LC-MS. This fact, coupled with the ability to phenotype a patient's polyclonal repertoire in the same analysis further shows the potential of this approach to mAb analysis.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Mills
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States.|Rheumatology Department, Brest University Hospital , 29609 Brest, Cedex, France.
authors.forename: Divi
authors.initials: D
authors.lastname: Cornec
authors.affiliation: Department of Health Sciences Research, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: Surendra
authors.initials: S
authors.lastname: Dasari
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Ladwig
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: Amber M
authors.initials: AM
authors.lastname: Hummel
authors.affiliation: Genentech Inc. , South San Francisco, California 94080, United States.
authors.forename: Melissa
authors.initials: M
authors.lastname: Cheu
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: David L
authors.initials: DL
authors.lastname: Murray
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Willrich
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Snyder
authors.affiliation: Cleveland Clinic Foundation , Cleveland, Ohio 44195, United States.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Hoffman
authors.affiliation: University of Groningen , 9712 CP Groningen, The Netherlands.
authors.forename: Cees G M
authors.initials: CG
authors.lastname: Kallenberg
authors.affiliation: Cleveland Clinic Foundation , Cleveland, Ohio 44195, United States.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Langford
authors.affiliation: University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Merkel
authors.affiliation: Boston University Medical Center , Boston, Massachusetts 02115, United States.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Monach
authors.affiliation: Johns Hopkins University , Baltimore, Maryland 21218, United States.
authors.forename: Philip
authors.initials: P
authors.lastname: Seo
authors.affiliation: Hospital for Special Surgery , New York, New York 10021, United States.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spiera
authors.affiliation: Duke University , Durham, North Carolina 27710, United States.
authors.forename: E William
authors.initials: EW
authors.lastname: St Clair
authors.affiliation: Massachusetts General Hospital , Boston, Massachusetts 02114, United States.
authors.forename: John H
authors.initials: JH
authors.lastname: Stone
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Specks
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States.
authors.forename: David R
authors.initials: DR
authors.lastname: Barnidge
mesh_terms: D000465:Algorithms; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000188:drug therapy / Q000378:metabolism; D000906:Antibodies / Q000276:immunology; D061067:Antibodies, Monoclonal, Humanized / Q000097:blood / Q000276:immunology / Q000627:therapeutic use; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D057230:Limit of Detection; D010641:Phenotype; D000069283:Rituximab / Q000097:blood* / Q000276:immunology / Q000627:therapeutic use; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000906:Antibodies; D061067:Antibodies, Monoclonal, Humanized; D000069283:Rituximab; C543529:vedolizumab