title: Accelerated clearance of polyethylene glycol-modified proteins by anti-polyethylene glycol IgM.
abstract: Tumor therapy by the preferential activation of a prodrug at tumor cells targeted with an antibody-enzyme conjugate may allow improved treatment efficacy with reduced side effects. We examined antibody-mediated clearance of poly(ethylene glycol)-modified beta-glucuronidase (betaG-sPEG) as a method to reduce serum concentrations of enzyme and minimize systemic prodrug activation. Enzyme-linked immunosorbent assay and immunoblot analysis of two monoclonal antibodies generated by immunization of BALB/c mice with an antibody-betaG-sPEG conjugate showed that mAb 1E8 (IgG1) bound betaG and betaG-sPEG whereas mAb AGP3 (IgM) bound poly(ethylene glycol). Neither antibody affected the betaG activity. mAb 1E8 and AGP3 were modified with 36 and 208 galactose residues (1E8-36G and AGP3-208G) with retention of 72 and 48% antigen-binding activity, respectively, to target immune complexes to the asialoglycoprotein receptor on liver cells. mAb 1E8 and AGP3 cleared betaG-PEG from the circulation of mice as effectively as 1E8-36G and AGP3-208G, respectively. mAb AGP3, however, cleared betaG-sPEG more completely and rapidly than 1E8, reducing the serum concentration of betaG-sPEG by 38-fold in 8 h. AGP3 also reduced the concentration of an antibody-betaG-sPEG conjugate in blood by 280-fold in 2 h and 940-fold in 24 h. AGP3-mediated clearance did not produce obvious damage to liver, spleen, or kidney tissues. In addition, AGP3 clearance of betaG-sPEG before administration of BHAMG, a glucuronide prodrug of p-hydroxyaniline mustard, prevented toxicity associated with systemic activation of the prodrug based on mouse weight and blood cell numbers. AGP3 should be generally useful for accelerating the clearance of PEG-modified proteins as well as for improving the tumor/blood ratios of antibody-betaG-PEG conjugates for glucuronide prodrug therapy of cancer.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: T L
authors.initials: TL
authors.lastname: Cheng
authors.forename: P Y
authors.initials: PY
authors.lastname: Wu
authors.forename: M F
authors.initials: MF
authors.lastname: Wu
authors.forename: J W
authors.initials: JW
authors.lastname: Chern
authors.forename: S R
authors.initials: SR
authors.lastname: Roffler
mesh_terms: D000816:Aniline Mustard / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism; D005260:Female; D005690:Galactose / Q000737:chemistry / Q000276:immunology; D005966:Glucuronidase / Q000737:chemistry / Q000493:pharmacokinetics*; D007075:Immunoglobulin M / Q000276:immunology* / Q000378:metabolism; D008657:Metabolic Clearance Rate; D051379:Mice; D008807:Mice, Inbred BALB C; D011092:Polyethylene Glycols / Q000737:chemistry / Q000493:pharmacokinetics*; D011355:Prodrugs / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D007075:Immunoglobulin M; D011355:Prodrugs; C071879:p-hydroxyaniline mustard glucuronide, tetra-n-butyl ammonium salt; D011092:Polyethylene Glycols; D000816:Aniline Mustard; D005966:Glucuronidase; D005690:Galactose