Charge variants of proposed biosimilar to Omalizumab: Isolation, purification and analysis by HPLC methods

Omalizumab (Xolair) is a humanized monoclonal antibody derived by recombinant DNA technology. It binds specifically to immunoglobulin E (IgE) which plays a major role in allergic reaction by releasing histamine and other inflammatory factors from mast cells. Omalizumab binds circulatory IgE with high affinity and prevents from its binding to mast cell receptor. Charge variants are one of the critical quality attributes (CQAs) in biological drug development and sources of heterogeneity which needs to be considered in biosimilarity assessment. In this study, biosimilar product of Xolair was expressed in mammalian cell culture process in laboratory to isolate charge variants (acidic, main peak and basic). Different charge variants were isolated from intermediate purified biosimilar product of Xolair. Isolated charge variants were purified with preparative cation exchange chromatography technique and characterized with different analytical tools includes size exclusion chromatography (SEC-HPLC) and cation exchange chromatography (CEX-HPLC). Purity of acidic, main peak and basic variants was 99.58%, 99.98% and 98.64% respectively as per SEC-HPLC and according to CEX-HPLC purity was 94.25%, 95.58% and 91.33% respectively. The study data indicates that isolated charge variants were purified with desired purity and can be further used for process characterization, in vitro potency and in vivo kinetics studies.