Analysis of Charge Variant Profiles in Antibody Conjugates

The aim of this study was to analyze the charge variant profiles of both unconjugated and conjugated antibodies. The first antibody exhibited the lowest alkalinity, with isoelectric point (pI) values ranging from 7.7 to 8.2. This was followed by the second antibody, which had pI values between 8.3 and 8.6. The third antibody was identified as the most alkaline, displaying pI values from 8.95 to 9.00. The first antibody was conjugated to a maytansine derivative via linkers, while the second and third antibodies were linked to tomaymycin. The conjugated antibodies demonstrated increased heterogeneity and more acidic characteristics compared to their unconjugated counterparts. Specifically, the first antibody conjugated with the maytansine derivative had a pI range of 7.0 to 8.1 (∆pI: 1.1), the second antibody with tomaymycin ranged from 7.8 to 8.4 (∆pI: 0.6), and the third antibody had pI values from 8.3 to 8.8 (∆pI: 0.5). The charge variant profiles obtained through imaging capillary isoelectric focusing exhibited high repeatability both within and across days.