No impact on patient safety and efficacy is identified since the products are within release/stability specifications. This investigation is to perform data analysis to understand whether any potential changes/variability may affect product quality. Detailed and extensive data analysis concluded that the CUB assay is potentially one of the contributing factors; and there is no direct evidence of the DP above mean trend being due to a DS quality shift. The trend was observed probably because the CUB assay variability outweighs the trend based on the facts that Glycan PG1 is a direct indication of enzyme update and the observed significant statistical relationship between combined site DS PG1 and DP CUB. Since this current CUB assay is being performed using self-control, an independent assay control as a CAPA action (PR965715) is being evaluated to improve assay performance and/or capacity.