title: Charge variants in IgG1: Isolation, characterization, in vitro binding properties and pharmacokinetics in rats.
abstract: Antibody charge variants have gained considerable attention in the biotechnology industry due to their potential influence on stability and biological activity. Subtle differences in the relative proportions of charge variants are often observed during routine biomanufacture or process changes and pose a challenge to demonstrating product comparability. To gain further insights into the impact on biological activity and pharmacokinetics (PK) of monoclonal antibody (mAb) charge heterogeneity, we isolated the major charge forms of a recombinant humanized IgG1 and compared their in vitro properties and in vivo PK. The mAb starting material had a pI range of 8.7-9.1 and was composed of about 20% acidic variants, 12% basic variants, and 68% main peak. Cation exchange displacement chromatography was used to isolate the acidic, basic, and main peak fractions for animal studies. Detailed analyses were performed on the isolated fractions to identify specific chemical modification contributing to the charge differences, and were also characterized for purity and in vitro potency prior to being administered either subcutaneously (SC) or intravenously (IV) in rats. All isolated materials had similar potency and rat FcRn binding relative to the starting material. Following IV or SC administration (10 mg/kg) in rats, no difference in serum PK was observed, indicating that physiochemical modifications and pI differences among charge variants were not sufficient to result in PK changes. Thus, these results provided meaningful information for the comparative evaluation of charge-related heterogeneity of mAbs, and suggested that charge variants of IgGs do not affect the in vitro potency, FcRn binding affinity, or the PK properties in rats.
authors.affiliation: Department of Pharmacokinetic and Pharmacodynamic Sciences, Genentech, Inc., South San Francisco, CA, USA. khawli.leslie@gene.com
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Khawli
authors.forename: Sirj
authors.initials: S
authors.lastname: Goswami
authors.forename: Ryan
authors.initials: R
authors.lastname: Hutchinson
authors.forename: Zephania W
authors.initials: ZW
authors.lastname: Kwong
authors.forename: Jihong
authors.initials: J
authors.lastname: Yang
authors.forename: Xiangdan
authors.initials: X
authors.lastname: Wang
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Yao
authors.forename: Alavattam
authors.initials: A
authors.lastname: Sreedhara
authors.forename: Tony
authors.initials: T
authors.lastname: Cano
authors.forename: Devin
authors.initials: D
authors.lastname: Tesar
authors.forename: Ihsan
authors.initials: I
authors.lastname: Nijem
authors.forename: David E
authors.initials: DE
authors.lastname: Allison
authors.forename: Pin Yee
authors.initials: PY
authors.lastname: Wong
authors.forename: Yung-Hsiang
authors.initials: YH
authors.lastname: Kao
authors.forename: Cynthia
authors.initials: C
authors.lastname: Quan
authors.forename: Amita
authors.initials: A
authors.lastname: Joshi
authors.forename: Reed J
authors.initials: RJ
authors.lastname: Harris
authors.forename: Paul
authors.initials: P
authors.lastname: Motchnik
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000493:pharmacokinetics*; D002852:Chromatography, Ion Exchange; D007074:Immunoglobulin G / Q000737:chemistry*; D007700:Kinetics; D051381:Rats
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G
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