Investigating residual trace metals in recombinant monoclonal antibodies to facilitate drug development with...

The biopharmaceutical industry is increasingly interested in the analysis of trace metals due to their significant impact on product quality and drug safety. Certain metals can potentially accelerate the formation of degradants or aggregates in biotherapeutic proteins, leading to drug product quality concerns. A better understanding of metal-mAb interactions would aid in the development of purification processes and formulations, thereby ensuring better drug quality and safety. An efficient analytical method to analyze metal-mAb interactions and identify metal binding molecules is needed.

This article presents a novel approach combining native size-exclusion chromatography (nSEC)-UV detection with inductively coupled plasma mass spectrometry (ICPMS) and nano-electrospray ionization (nano-ESI) high resolution mass spectrometry (HRMS) for simultaneous detection of metals and identification of metal binding molecules, including biotherapeutics and small molecules in drug substances and products. With this method, several metals, including chromium, manganese, iron, cobalt, nickel, copper and zinc, were found to bind the bispecific antibody mAb1. In addition, iron and copper were found to bind small molecules, such as histidine, citrate or sucrose present in drug substances. The developed platform was further used to study an IgG1 mAb (mAb2). A high iron binding capacity was observed for mAb2. Through integrated enzyme assisted subunit analysis, we further identified that iron binds predominantly the mAb Fab domain.

This LC-UV-ICPMS-HRMS method enables deeper understanding of metal-mAb interactions and offers information on both metal and metal-binding molecules in a single experiment, thus saving time and minimizing sample consumption. Consequently, this method can effectively and directly facilitate exploration of metal-mAb interactions during drug development.