Zhengqi Zhang

Senior Scientist at Merck

Speaker

Antibody-drug conjugates (ADCs) are monoclonal antibodies linked to potent small-molecule chemotherapy agents. They are designed to improve targeted cancer therapy by reducing systemic toxicity and enhancing efficacy. A critical step in cysteine-based ADC manufacturing is the conjugation reaction, which involves reducing interchain disulfide bonds. Optimizing this process is complex and time-intensive, requiring thorough evaluation of multiple parameters to achieve optimal reduction and conjugation efficiency.

The drug-to-antibody ratio (DAR) is a key quality attribute influencing ADC pharmacokinetics and pharmacodynamics. Therefore, robust, real-time monitoring of DAR throughout manufacturing is essential to support process development and ensure consistent product quality. Traditional methods such as HIC-LC and RP-LC (with UV detection) face challenges including lengthy sample preparation, long analysis times, and limited peak identification capabilities, hindering real-time monitoring.

To overcome these limitations, we developed and systematically evaluated a high-throughput, online desalting size-exclusion chromatography-mass spectrometry (SEC-MS) method coupled with a post-column denaturation strategy for rapid assessment of reduction efficiency and DAR measurement. This method requires no sample preparation and achieves data acquisition in one minute per sample. Its analytical performance was benchmarked against HIC-LC and RP-LC standards.