Comparative analysis of Herceptin N-Linked glycosylation by HILIC-FLD and LC-MS/MS methods

Monoclonal antibodies like Herceptin play a pivotal role in modern therapeutics, with their glycosylation patterns significantly influencing their bioactivity. To characterize the N-glycan profile and their relative abundance in Herceptin, we employed two analytical methods: hydrophilic interaction chromatography with fluorescence detection (HILIC-FLD) for released glycans and liquid chromatography tandem mass spectrometry (LC-MS/MS) for glycopeptides. Our analysis included 21 European Union (EU)-Herceptin lots and 14 United States (US)-Herceptin lots. HILIC-FLD detected 25 glycan species, including positional isomers, revealing comparable chromatographic profiles for both EU and US lots. On the other hand, LC-MS/MS identified 26 glycoforms within the glycopeptide EEQYNSTYR. Both methods showed that a subset of glycans dominated the total abundance. Notably, EU-Herceptin lots with an expiration date of October 2022 exhibited increased levels of afucosylated and high mannose N-glycans. Our statistical comparisons showed that the difference in quantitative results between HILIC-FLD and LC-MS/MS is significant, indicating that the absolute quantitative values depend on the choice of the analytical method. However, despite these differences, both methods demonstrated a strong correlation in relative glycan proportions. This study contributes to the comprehensive analysis of Herceptin's glycosylation, offering insights into the influence of analytical methods on glycan quantification and providing valuable information for the biopharmaceutical industry.

Impacts of fast production of afucosylated antibodies and Fc mutants in ExpiCHO-S™ for enhancing FcγRIIIa binding and NK cell activation

This study has employed mammalian transient expression systems to generate afucosylated antibodies and antibody Fc mutants for rapid candidate screening in discovery and early development. While chemical treatment with the fucose analogue 2-fluoro-peracetyl-fucose during transient expression only partially produced antibodies with afucosylated N-glycans, the genetic inactivation of the FUT8 gene in ExpiCHO-S™ by CRISPR/Cas9 enabled the transient production of fully afucosylated antibodies. Human IgG₁ and murine IgG_2a generated by the ExpiCHOfut8KO cell line possessed a 8-to-11-fold enhanced FcγRIIIa binding activity in comparison with those produced by ExpiCHO-S™. The Fc mutant S239D/S298A/I332E produced by ExpiCHO-S™ had an approximate 2-fold higher FcγRIIIa affinity than that of the afucosylated wildtype molecule, although it displayed significantly lower thermal-stability. When the Fc mutant was produced in the ExpiCHOfut8KO cell line, the resulting afucosylated Fc mutant antibody had an additional approximate 6-fold increase in FcγRIIIa binding affinity. This synergistic effect between afucosylation and the Fc mutations was further verified by a natural killer (NK) cell activation assay. Together, these results have not only established an efficient large-scale transient CHO system for rapid production of afucosylated antibodies, but also confirmed a cooperative impact between afucosylation and Fc mutations on FcγRIIIa binding and NK cell activation.

Enhancement of effector functions of anti-CD20 monoclonal antibody by increased afucosylation in CHO cell line through cell culture medium optimization

Background

Recombinant therapeutic anti-CD20 monoclonal antibody (mAb) is used for the treatment of non-Hodgkin’s lymphoma, a common B cell lymphoma constituting 80% of all lymphomas. Anti-CD20 mAb contains an Fc-linked biantennary glycan. Although, anti-CD20 monoclonal antibodies are being increasingly used for immunotherapy, their efficacy is limited in a section of patients with drug resistance to immunotherapy. There is a need to improve the efficacy by increasing the effector functions, such as the antibody-dependent cellular cytotoxicity (ADCC) activity of anti-CD20 monoclonal antibodies.

Results

We developed a simple and cost-effective approach to enhance ADCC effector activity in an in-house developed clone of anti-CD20 monoclonal antibody by increasing afucosylation in a new clone of Chinese Hamster Ovary (CHO) cells using 8X uridine, manganese, and galactose (UMG) to modulate the osmolality of the medium. The purified anti-CD20 monoclonal antibody from 8X UMG-containing medium showed a 2-fold increase in afucose content and 203% ADCC activity in comparison to control antibody.

Conclusions

Our study reports enhanced ADCC activity by modulating afucosylation using osmolality by altering simple feed additives in the culture medium.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00421-5.

Identification of a Guinea Pig Fcγ Receptor that Exhibits Enhanced Binding to Afucosylated Human and Mouse IgG

Glyco-engineered recombinant antibodies are currently being developed as the next generation therapeutics to treat human diseases, including cancer, autoimmunity and infection. Antibodies lacking core fucosylation show great increase in affinity for FcγRIIIA, leading to an improved receptor-mediated effector function. While afucosyl human IgG1 exhibits 50-100-fold increase in antibody-mediated cellular cytotoxicity (ADCC), a key immune effector mechanism underlying the anti-cancer effect of some approved therapeutic antibodies, it is not clear whether such glyco-engineered antibodies would find similar use for infectious disease. Due to the species difference, human antibodies may have different binding properties towards corresponding IgG receptors from animals used for modeling infection and intoxication. During the course of studying a recombinant human IgG1 in neutralizing diphtheria toxin (DT) in Guinea pigs (Cavia porcellus), we identified a previously uncharacterized Guinea pig protein H0VDZ8 from UNIPROT database that shows high sequence homologies to human FcγRIIIA and mouse FcγRIV. This Fcγ receptor, which we named as gpFcγRIV, also demonstrates functional similarity although not to the same extent as the human and mouse counterparts, in that it binds to afucosyl human and mouse IgG much stronger than to the wild type antibodies. Thus, Guinea pigs can be used to compare the efficacies of wild type vs. afucosyl anti-DT human IgG1 in toxin removal and animal protection. Molecular and functional characterization of human FcγRIIIA and mouse FcγRIV equivalents in other species could expand the list of preclinical animal models for testing afucosyl human antibodies in treating various human diseases.

In vivo anti-tumor efficacy of afucosylated anti-CS1 monoclonal antibody produced in glycoengineered Pichia pastoris

Monoclonal antibody (mAb) therapy has been successfully used for the treatment of B-cell lymphomas and is currently extended for the treatment of multiple myeloma (MM). New developments in MM therapeutics have achieved significant survival gains in patients but the disease still remains incurable. Elotuzumab (HuLuc63), an anti-CS1 monoclonal IgG1 antibody, is believed to induce anti-tumor activity and MM cytotoxicity through antibody dependent cellular cytotoxicity (ADCC) and inhibition of MM cell adhesion to bone marrow stromal cells (BMSCs). Modulations of the Fc glycan composition at the N297 site by selective mutations or afucosylation have been explored as strategies to develop bio-better therapeutics with enhanced ADCC activity. Afucosylated therapeutic antibodies with enhanced ADCC activity have been reported to possess greater efficacy in tumor growth inhibition at lower doses when compared to fucosylated therapeutic antibodies. The N-linked glycosylation pathway in Pichia pastoris has been engineered to produce human-like N-linked glycosylation with uniform afucosylated complex type glycans. The purpose of this study was to compare afucosylated anti-CS1 mAb expressed in glycoengineered Pichia pastoris with fucosylated anti-CS1 mAb expressed in mammalian HEK293 cells through in vitro ADCC and in vivo tumor inhibition models. Our results indicate that Fc glycosylation is critical for in vivo efficacy and afucosylated anti-CS1 mAb expressed in glycoengineered Pichia pastoris shows a better in vivo efficacy in tumor regression when compared to fucosylated anti-CS1 mAb expressed in HEK293 cells. Glycoengineered Pichia pastoris could provide an alternative platform for generating homogeneous afucosylated recombinant antibodies where Fc mediated immune effector function is important for efficacy.