Generation and Biological Characterization of an Anti-IL-6Rα Biosimilar Candidate Antibody

Tocilizumab is a monoclonal antibody (mAb) that recognizes human Interleukin 6 receptor alpha (IL-6Rα) and antagonizes IL-6 signaling. It is therefore used in the treatment of moderate to severe rheumatoid arthritis in patients with inadequate response to antirheumatic drugs, and in the treatment of systemic juvenile idiopathic arthritis. During the course of the Coronavirus Disease 2019 (COVID-19) pandemic, the potential application of Tocilizumab in severe inflammatory diseases was demonstrated. In addition, the drug is attracting increasing attention for its potential application in other pathologies, particularly cancers where the central role of Interleukin 6 (IL-6) has been described, such as pancreatic ductal adenocarcinoma. The necessity for further research in this area is far too great, which is why the development of additional biosimilars is both necessary and welcome. In this work, we describe the generation and biological characterization of a biosimilar candidate of Tocilizumab. A stable producing CHO-K1 cell line was obtained by lentiviral transduction. We demonstrated that the antibody generated, named 41TB, has similar size heterogeneity and electrophoretic profile as Tocilizumab, and high levels of purity. Moreover, 41TB exhibits comparable binding capacity to IL-6Rα, as well as the ability to interrupt IL-6/IL-6Rα binding in ELISA. Additionally, both antibodies were likewise able to inhibit DS-1 cell proliferation, IL-6 induced STAT3 phosphorylation, and C-Reactive Protein production in vitro. Galactose supplementation of the culture medium appears to be necessary to generate a glycosylation profile similar to the original antibody.