ABSTRACT
Fc galactosylation is a critical quality attribute for anti-tumor recombinant immunoglobulin G (IgG)-based monoclonal antibody (mAb) therapeutics with complement-dependent cytotoxicity (CDC) as the mechanism of action. Although the correlation between galactosylation and CDC has been known, the underlying structure-function relationship is unclear. Heterogeneity of the Fc N-glycosylation produced by Chinese hamster ovary (CHO) cell culture biomanufacturing process leads to variable CDC potency. Here, we derived a kinetic model of galactose transfer reaction in the Golgi apparatus and used this model to determine the correlation between differently galactosylated species from CHO cell culture process. The model was validated by a retrospective data analysis of more than 800 historical samples from small-scale and large-scale CHO cell cultures. Furthermore, using various analytical technologies, we discovered the molecular basis for Fc glycan terminal galactosylation changing the three-dimensional conformation of the Fc, which facilitates the IgG1 hexamerization, thus enhancing C1q avidity and subsequent complement activation. Our study offers insight into the formation of galactosylated species, as well as a novel three-dimensional understanding of the structure-function relationship of terminal galactose to complement activation in mAb therapeutics.
Subject(s)
Antibodies, Monoclonal/pharmacology , Complement Activation/drug effects , Complement C1q/agonists , Cytotoxicity, Immunologic/drug effects , Galactose/metabolism , Immunoglobulin Fc Fragments/pharmacology , Immunoglobulin G/pharmacology , Protein Processing, Post-Translational , Animals , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/genetics , Antibodies, Monoclonal/metabolism , CHO Cells , Complement C1q/metabolism , Cricetulus , Immunoglobulin Fc Fragments/chemistry , Immunoglobulin Fc Fragments/genetics , Immunoglobulin Fc Fragments/metabolism , Immunoglobulin G/chemistry , Immunoglobulin G/genetics , Immunoglobulin G/metabolism , Kinetics , Models, Biological , Protein Multimerization , Structure-Activity RelationshipABSTRACT
BACKGROUND: A 48-year-old woman with chronic urinary tract infections presented with uremia. Imaging studies revealed bilateral hydronephrosis and segmental ureteral thickening. INVESTIGATIONS: Physical examination, urine and blood analysis, radiography of the chest, chest CT, abdominal and pelvis CT, renal ultrasonography, cystoscopy, anterograde pyelogram, bladder biopsy. DIAGNOSIS: Malacoplakia involving bilatateral ureters and bladder; cavitary pneumonia. MANAGEMENT: Hemodialysis, placement of bilateral percutaneous nephrostomy tubes, administration of ciprofloxacin, ascorbic acid and bethanechol.