By Fang Wang, Andras Guttman, Mark Lies, and Sahana Mollah, SCIEX
Therapeutic proteins are a rapidly growing class of biologics. The introduction of monoclonal antibody (mAb) drugs has transformed the pharmaceutical landscape to combat a number of clinical conditions, including cancer and autoimmune disease. The introduction of new modalities, including bi- and tri-specific antibodies, antibody-drug conjugates, and fusion proteins, is increasing. Protein therapeutic charge variant assessment is essential at different manufacturing stages as they are subjected to instability, causing alterations in their primary amino acid sequence and variable post-translational modification (PTM). These changes can often be detected by changes in the protein isoelectric point. Therefore, robust and reproducible techniques for charge variant characterization are of high importance. A frequently used high precision technique to characterize charge heterogeneity of recombinant protein therapeutics is isoelectric focusing. In this technical note, we demonstrate parallel, highly reproducible capillary isoelectric focusing analysis using a multi-capillary separation approach to accelerate analysis time.