Assessing the Impact of Charge Variants on Stability and Viscosity of a High Concentration Antibody Formulation

Characterizing molecular charge variants or isoforms is essential for understanding safety, potency, and bioavailability of antibody therapeutics. However, there is little information on how they influence stability and viscosity-properties governing immunogenicity and delivery. To bridge this gap, we studied antibody stability as a function of charge variant content generated via bioreactor process. We were able to systematically vary acidic variant levels as a function of bioreactor harvest time. Importantly, we do not observe any impact on aggregation behavior of a formulated antibody at high protein concentration as a function of acidic variant level. Furthermore, we confirm that acidic variants enriched using fractionation do not influence viscosity, colloidal or conformational stability. Interestingly, variants with the most acidic isoelectric points contribute disproportionately to formulation color. We discuss our findings in context of antibody manufacturing processes that may yield increased charge variant content.