Characterization and comparison of commercially available TNF receptor 2-Fc fusion protein products

624 mAbs Volume 5 Issue 5 Dear Dr Reichert, The emerging area of biosimilars to large complex protein molecules such as antibodies brings with it many challenges, both for biotechnology manufacturers as well as regulatory authorities. We read with interest your recent article by Tan et al. that, for us, highlighted these challenges previously referred to as a knowledge gap between the innovator and the biosimilar developer. It is of considerable importance for patients that biosimilars become available on the market, however it is equally imperative that these biosimilars meet the same standards of safety and efficacy as the innovator products. With this in mind, we have a number of comments on the article by Tan et al. The authors performed an analysis of two purported etanercept biosimilars which they obtained from the Chinese market. The analysis included primary sequence, peptide mapping, intact mass, charge variants, glycosylation, bioactivity, and affinity. The comparisons were made against Enbrel as the innovator molecule. Analyses were performed on four lots of “biosimilar 1,” one lot of “biosimilar 2,” and one lot of Enbrel. Etanercept drug substance (DS) has been commercially manufactured since 1998, and marketed as the drug product (DP) Enbrel. The manufacturing process for Enbrel has been optimised over time and extensive biochemical characterization analyses have been performed to demonstrate comparability and ensure consistency. This long manufacturing history has allowed Pfizer to develop a Characterization and comparison of commercially available TNF receptor 2-Fc fusion protein products Letter to the Editor