Charge heterogeneity in monoclonal antibodies can negatively impact binding affinity and potency, so it is critical to ensure that individual charge variants of biotherapeutic molecules are thoroughly characterized to ensure product quality. Dr. Chris Heger (Bio-Techne) and Dr. Mike Piazza (Nicoya Lifesciences) will illustrate a fast, simple icIEF fractionation and digital SPR workflow that provides in-depth characterization of the charge variants of a therapeutic bispecific antibody (BsAb) Mosunetuzumab and a research-grade biosimilar. Using a combination of the MauriceFlex™ system and Alto™ Digital SPR, they demonstrate a novel method that utilizes imaged capillary isoelectric focusing (icIEF)-based charge separation and fractionation followed by binding affinity analysis using surface plasmon resonance, offering a robust and efficient approach to evaluating charge variants. Prior LC-MS analysis of the fractions uncovered interesting differences between the two molecules. The speakers will show how the high-purity fractions of both the innovator drug and a research-grade biosimilar were analyzed by SPR for binding studies with their ligands CD3 and CD20, revealing notable differences in binding affinity, particularly between the biosimilar’s acidic peak and ligand CD20.
