Assessment of structural and functional similarity of biosimilar products: Bevacizumab as a case study

The antiangiogenic drug bevacizumab is a blockbuster therapeutic pharmaceutical product that is used to treat many different types of cancer including kidney, colon, rectum, lung, and breast cancer. As a result, multiple biosimilars have been approved across the various regulatory jurisdictions in India (>20 in number till date). The rapidly growing market and acceptance of biosimilars was the motivation to perform comparability study of bevacizumab biosimilars that are presently available in the Indian market. A comprehensive analytical and functional biosimilarity assessment has been performed to examine and compare innovator product of bevacizumab (Avastin-innovator product, Roche Products (India) Pvt Ltd) and six biosimilars that are being marketed in India (Abevmy from Mylan Pharmaceuticals Pvt Ltd, Bevazza from Lupin Ltd, Bryxta from Zydus Cadila, Krabeva from Biocon, Ivzumab from RPG Life Sciences Ltd, and Advamab from Alkem Laboratories Ltd). Physiochemical characterization of drug products was performed with respect to their primary structure (intact mass, reduced mass, peptide mapping by LC-MS), higher order structure (secondary structure by FTIR, Far-UV-CD, and tertiary structure by Near-UV-CD, intrinsic fluorescence spectroscopy), impurity profile (SE-HPLC, SEC-MALS, extrinsic fluorescence: size heterogenicity, degradation, stability; DLS: hydrodynamic radius; WCX-HPLC: charge variants analysis) and post-translational modifications by measuring reduced glycans through fluorescence dye analysis. Functional characterization was performed by SPR and cell proliferation assay. Further, chemometrics based quantitative evaluation of biosimilarity has been performed by combining the data obtained from analytical characterization platform. The analysis of the analytical, functional and chemometric results revealed significant levels of similarity, with biosimilar4 being the sole exception. Despite being within product specifications, Biosimilar4 displayed significant deviations with respect to critical quality attributes, including a lower proportion of monomer content, a larger percentage of basic charge variant species, and a lower proportion of aglycosylated glycoform.