Achieving charge variant profile of innovator molecule during development of monoclonal antibody based biosimilars – Use of media components

Recombinant monoclonal antibodies are primarily expressed in Chinese Hamster Ovary (CHO) cell lines. Post-translational modifications (PTMs) in biotherapeutics contribute significantly to population heterogeneity with respect to charge and glycosylation. Cell culture medium components are known to significantly contribute to PTMs. This study aims to target the charge variant profile of an innovator molecule Herceptin® by using metal ions as charge variant modulators. Inhouse produced trastuzumab was found to have significantly lower acidic variants (17.64 ± 1.07% acidic and 12.86 ± 0.43% basic) compared to the innovator product (24.97 ± 0.54% acidic and 11.41 ± 1.44% basic). Following a thorough investigation, zinc was chosen to regulate the basic charge variations, whereas iron was used to alter the acidic charge variants. With supplementation of the metal ion at optimal concentration, the charge variant profile for the in-house mAb (24.7 ± 0.83% acidic and 14.4 ± 0.64% basic) was near identical to that of the innovator product. While minor reduction in viable cell density and product titer were observed (~7%), there was no significant impact on other quality attributes including glycans and specific productivity of cells. This study would be of high interest to biosimilar manufacturers who strives to demonstrate the analytical and functional biosimilarity of their products to the innovator.