title: Evaluation of near infrared fluorescent labeling of monoclonal antibodies as a tool for tissue distribution.
abstract: The pharmacokinetic (PK) behavior of monoclonal antibodies (mAbs) is influenced by target-mediated drug disposition, off-target effects, antidrug antibody-mediated clearance, and interaction with fragment-crystallizable domain (Fc) receptors such as neonatal Fc receptor. All of these interactions hold the potential to impact mAb biodistribution. Near infrared (NIR) fluorescent probes offer an approach complementary to radionuclides to characterize drug disposition. Notably, the use of FDA-approved IRDye800 (IR800; LI-COR, Lincoln, NE) as a protein-labeling agent in preclinical work holds the potential for quantitative tissue analysis. Here, we tested the utility of the IR800 dye as a quantitative mAb tracer during pharmacokinetic analysis in both plasma and tissues using a model mouse monoclonal IgG1 (8C2) labeled with ≤1.5 molecules of IR800. The plasma PK parameters derived from a mixture of IR800-8C2 and 8C2 dosed intravenously to C57BL/6 mice at 8 mg/kg exhibited a large discrepancy in exposure depending on the method of quantitation [CLplasma = 8.4 ml/d per kilogram (NIR fluorescence detection) versus 2.5 ml/d per kilogram (enzyme-linked immunosorbent assay)]. The disagreement between measurements suggests that the PK of 8C2 is altered by addition of the IR800 dye. Additionally, direct fluorescence analysis of homogenized tissues revealed several large differences in IR800-8C2 tissue uptake when compared with a previously published study using [(125)I]8C2, most notably an over 4-fold increase in liver concentration. Finally, the utility of IR800 in combination with whole body imaging was examined by comparison of IR800-8C2 levels observed in animal sagittal cross-sections to those measured in homogenized tissues. Our results represent the first PK analysis in both mouse plasma and tissues of an IR800-mAb conjugate and suggest that mAb disposition is significantly altered by IR800 conjugation to 8C2.
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.).
authors.forename: Kip P
authors.initials: KP
authors.lastname: Conner
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.) drock@amgen.com.
authors.forename: Brooke M
authors.initials: BM
authors.lastname: Rock
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.).
authors.forename: Gayle K
authors.initials: GK
authors.lastname: Kwon
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.).
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Balthasar
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.).
authors.forename: Lubna
authors.initials: L
authors.lastname: Abuqayyas
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.).
authors.forename: Larry C
authors.initials: LC
authors.lastname: Wienkers
authors.affiliation: Biochemistry and Biophysics Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Seattle, Washington (K.P.C., B.M.R., G.K.K., L.C.W., D.A.R.); Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, New York (J.P.B.); and Quantitative Pharmacology Group in Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California (L.A.) drock@amgen.com.
authors.forename: Dan A
authors.initials: DA
authors.lastname: Rock
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019265:Spectroscopy, Near-Infrared; D014018:Tissue Distribution
chemical_list: D000911:Antibodies, Monoclonal; D005456:Fluorescent Dyes