Physicochemical and Biological Characterization of the Proposed Biosimilar Tocilizumab.

HS628 has been developed as a proposed biosimilar product of originator tocilizumab (Actemra®). An extensive physicochemical and biological characterization was conducted to assess similarity between HS628 and originator tocilizumab. The amino acid sequence was shown to be identical between HS628 and originator tocilizumab. The higher order structure was found to be indistinguishable from originator tocilizumab. Concerning purity and heterogeneity, HS628 was demonstrated to have similar posttranslational modifications, charge heterogeneity, size heterogeneity, and glycosylation to originator tocilizumab. Moreover, HS628 exhibited highly similar binding affinity and antiproliferative activity as well as capability of inhibiting STAT3 phosphorylation compared to originator tocilizumab. Taken together, HS628 can be considered as a highly similar molecule to originator tocilizumab in terms of physicochemical and biological properties.