title: Implications of the presence of N-glycolylneuraminic acid in recombinant therapeutic glycoproteins.
abstract: Recombinant glycoprotein therapeutics produced in nonhuman mammalian cell lines and/or with animal serum are often modified with the nonhuman sialic acid N-glycolylneuraminic acid (Neu5Gc; refs. 1,2). This documented contamination has generally been ignored in drug development because healthy individuals were not thought to react to Neu5Gc (ref. 2). However, recent findings indicate that all humans have Neu5Gc-specific antibodies, sometimes at high levels. Working with two monoclonal antibodies in clinical use, we demonstrate the presence of covalently bound Neu5Gc in cetuximab (Erbitux) but not panitumumab (Vectibix). Anti-Neu5Gc antibodies from healthy humans interact with cetuximab in a Neu5Gc-specific manner and generate immune complexes in vitro. Mice with a human-like defect in Neu5Gc synthesis generate antibodies to Neu5Gc after injection with cetuximab, and circulating anti-Neu5Gc antibodies can promote drug clearance. Finally, we show that the Neu5Gc content of cultured human and nonhuman cell lines and their secreted glycoproteins can be reduced by adding a human sialic acid to the culture medium. Our findings may be relevant to improving the half-life, efficacy and immunogenicity of glycoprotein therapeutics.
authors.affiliation: Glycobiology Research and Training Center, Department of Medicine and Cellular & Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
authors.forename: Darius
authors.initials: D
authors.lastname: Ghaderi
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Taylor
authors.forename: Vered
authors.initials: V
authors.lastname: Padler-Karavani
authors.forename: Sandra
authors.initials: S
authors.lastname: Diaz
authors.forename: Ajit
authors.initials: A
authors.lastname: Varki
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology; D061067:Antibodies, Monoclonal, Humanized; D000918:Antibody Specificity; D002460:Cell Line; D000068818:Cetuximab; D003470:Culture Media / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry* / Q000276:immunology / Q000627:therapeutic use; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D051379:Mice; D019158:N-Acetylneuraminic Acid; D009438:Neuraminic Acids / Q000737:chemistry / Q000276:immunology*; D000077544:Panitumumab; D011994:Recombinant Proteins / Q000737:chemistry* / Q000276:immunology / Q000627:therapeutic use
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D003470:Culture Media; D006023:Glycoproteins; D007074:Immunoglobulin G; D009438:Neuraminic Acids; D011994:Recombinant Proteins; C032592:N-glycolylneuraminic acid; D000077544:Panitumumab; D019158:N-Acetylneuraminic Acid; D000068818:Cetuximab