Impact of photo-oxidation on long term storage of affinity chromatography media used in multi-specific antibody...

Large scale manufacture of complex biotherapeutic formats such as multi-specific antibodies can require development of custom biomanufacturing platforms, particularly for purification processes. Substantial advances in affinity chromatography media have allowed monoclonal antibody-like processes for these formats, and simplified process development to enable fast speed to the clinic. Thorough assessment of chromatography media performance and stability is critical to ensure robust operation and consistent product quality over repeated cycles throughout its lifetime. However, evaluation of repeated cycling and extended storage for chromatography media is resource consuming, which typically delays rigorous study to later development stages and often is acquired through increased operational experience. These areas can present quality risks if not properly understood. In this work, a class of affinity chromatography media employing camelid antibody-fragment ligands were evaluated for extended storage in benzyl alcohol solution as an alternative to ethanol storage. Initial laboratory studies revealed resin discoloration after 12 months of exposure to ambient light at room temperature. Resin photo-stress studies confirmed light exposure as the root cause, with benzyl alcohol storage conditions producing a substantially greater degree of discoloration compared to ethanol. Extreme photo-stress over the course of 7 days was also found to negatively impact resin dynamic binding capacities, with more severe declines observed with benzyl alcohol storage conditions. Binding capacity loss of 54 % was observed for photo-stressed CaptureSelect Kappa XP compared to control conditions. Addition of antioxidants reduced or eliminated resin discoloration during photo-stress, indicating that benzyl alcohol storage accelerates photo-oxidation of the affinity chromatography ligands. The addition of l-methionine to benzyl alcohol solution prevented resin discoloration and maintained a dynamic binding capacity of 41 g/L for CaptureSelect Kappa XP even after extreme photo-stress. Of practical importance, a study of LambdaFabSelect resin used and stored in benzyl alcohol solution, under recommended conditions (2-8 °C storage, protected from light) in an internal GMP facility over a period of three years, showed no impact to resin color, performance, or product quality.