Critical Quality Attribute Investigation and Analytical Method Establishment for Glyco-Site-Specific Anti-HER2 Bispecific ADC

Background/Objectives: Bispecific antibody–drug conjugates (bispecific ADCs) are among the most rapidly advancing antibody therapeutic modalities, with only one product (BL-B01D1) currently approved for marketing worldwide to date. In this study, we investigated several critical quality attributes (CQAs) of a glyco-site-specific antibody–drug conjugate (ADC) targeting two distinct epitopes of HER2. Methods: We established quality control methods for the assessment of mispaired species, conjugation site, drug-to-antibody ratios (DARs), charge variants, residual free drugs, residual β1,4-galactosyltransferase I (GalT) enzyme, relative binding activity, and cell proliferation inhibition activity. Conclusions: An analytical method suite was developed for the bispecific ADC to comprehensively characterize and appropriately control its critical quality attributes, thereby guiding the research, development, and manufacturing process optimization of the ADC product and ensuring its safety, efficacy, and quality consistency.