Intact Mass Quantitation of Therapeutic Antibodies for Pharmacokinetic Studies Using Immuno-Purification

The quantitation of therapeutic antibodies by mass spectrometry often utilizes a surrogate peptide approach following enzymatic digestion of the antibody. Although this approach has been widely adopted, it is labor intensive with limited throughput in most instances. In addition, this approach can pose challenges when attempting to infer details such as quantity and modification state of the intact analyte. Recent enhancements in instrumentation and sample preparation have enabled quantitation through mass spectrometry detection of the intact protein circumnavigating many limitations of the surrogate peptide approach. Presented here is a method for quantitative analysis of therapeutic monoclonal antibodies (mAb) at the fully intact level in a complex pharmacokinetic study. This methodology yielded sensitivity down to 0.1μg/mL from 30μL of a biological sample volume to be utilized across multiple preclinical species without the need for pooling.