Effects of thermal treatment on quality of biosimilar and originator monoclonal antibodies

Investigating products under stress conditions provides valuable information for assessing stability, biosimilarity, and degradation behaviors during monoclonal antibody (mAb) development. Proper sample preparation is crucial for accurately evaluating the biosimilarity and effects of stress conditions in comparability assessment, where these studies guide biosimilar mAb development steps. Enzymatic and chemical treatments applied during sample preparation of mAbs generally require treatment of samples in temperatures higher than the storage temperatures of antibodies.

In this study, samples of a TNF-α inhibitor IgG1 biosimilar (BIO) and its originator (OR) were treated for 7 days at commonly used temperatures during sample preparation. Alterations in the intact IgG, size variants, charge variants, binding kinetics, and post-translational modifications (PTMs) were investigated with CE-SDS, SE-UPLC, icIEF, SPR, and LC-MS/MS, respectively. Samples treated at 50 °C exhibited significant degradation, while minor differences were observed in samples treated at 37 °C. Monomer and intact IgG levels were decreased to levels below 97 % and 94 %, respectively, after 7 days of thermal treatment at 50 °C for both BIO and OR samples. Similar rates of degradation were observed between the treated biosimilar and originator samples. The percent monomer degradation rate between the biosimilar and the originators was similar at 50 °C (p = 0.32). Thermal treatment increased acidic variant levels in the products of the BIO (23.10 %) and OR (23.16 %). During post-translational modification monitoring, an increase in pyroglutamic acid formation and a decrease in C-terminal lysine were observed after thermal treatments. Acidic variant alterations were associated with asparagine deamidation and N-terminal pyroglutamic acid formation. Post-translational modifications were mainly located at the Fc domain, with methionine oxidation and asparagine deamidation as the main modifications occurring at the Fab domain.

In conclusion, these results revealed that prolonged thermal treatment under elevated temperatures induces molecular alterations, thereby facilitating the degradation of IgG1. In addition, our findings indicate that both BIO and OR lots exhibit similar degradation profiles when subjected to thermal treatments.