Development and validation of aggregates analysis method in analytical similarity assessment of HLX04 vs Avastin®

Aggregate of therapeutic antibodies is usually considered as one of the most important critical quality attributes (CQA). The propensity of aggregates formation for bevacizumab is higher than other monoclonal antibody (mAb) drugs due to its tendency of self-association via the non-covalent interaction between the Fab arm of one bevacizumab molecule and the K445 residue on the heavy chain of another bevacizumab molecule. HLX04 has been developed as a biosimilar to bevacizumab (Avastin®) by Shanghai Henlius Biotech. To perform a head-to-head similarity evaluation with respect to aggregates or higher molecular weight species (HMWS) between HLX04 and Avastin®, we developed a robust high performance liquid chromatography (SEC-HPLC) method for aggregates analysis. Our characterization data indicated that HMWS of bevacizumab were mainly composed of dimers, and the dimer formation-dissociation equilibrium was influenced by protein concentration and storage temperature. Based on the characterization data of aggregates, we optimized the key parameters for SEC-HPLC based aggregates analysis method including mobile phase components and pH, autosampler temperature, as well as incubation conditions for sample pretreatment. The developed method was applied in HLX04 and Avastin® aggregates assessment and the similarity were confirmed among HLX04, China-sourced, and Europe-sourced Avastin® using both the pharmaceutical dosage forms and forced degradation samples. The method was also validated per ICH Q2 (R1) guidelines by challenging the parameters including specificity, accuracy, precision, linearity, range, limit of quantitation, and robustness. The validated method was applied in release test and stability study of HLX04 samples generated from commercial manufacturing process.