In past few years many rituximab (RTX) biosimilars have been launched in India. Biosimilars are products that are similar in terms of quality, safety, and efficacy to its innovator product and are expected to offer improved affordability. The less clinical examination is a significant source of reduction in the cost of development of a biosimilar. However, this clinical relief is predicated on the assumption that there is analytical similarity between the biosimilar and the innovator product. Therefore, the role of National Control Laboratory become very important to ensure the quality of these drugs by carrying out analytical characterization at the point of drug product release level as when referred by National Regulatory Authority for quality evaluation. To assess the similarity between innovator and biosimilars, different physicochemical and biological quality attributes were assessed. A multitude of state-of-the-art analysis of N = 3 RTX biosimilars marketed in India revealed that the impurity profiles of these biosimilars measured by charge variant analysis (cation exchange chromatography-high performance liquid chromatography [HPLC], capillary zone electrophoresis, and capillary isoelectric focusing), aggregates profiling (size exclusion chromatography-HPLC), fragments analysis (capillary electrophoresis-sodium dodecyl sulfate) were found to be significantly varying as compared with the innovator product. There were significant variations in acidic variants (p = 0.023) and basic variants (p = 0.0005), isoelectric point value (p < 0.0001), aggregates (p = 0.0231), and fragments (p < 0.0001) of biosimilars were found as that of innovator product. However, these differences were not affecting the biological activity in the cell-based potency analysis by complement-dependent cytotoxicity (CDC) assay (p = 0.1026), antibody-dependent cell-mediated cytotoxicity (ADCC) (p = 0.3736), and binding assay by flow cytometer fluorescence-activated cell sorting (p = 0.4005) of these biosimilars as compared with the innovator product.
Keywords: CD20; CZE; FACS; bioassay; cIEF; rituximab.