Multiple reaction monitoring for quantitative biomarker analysis in proteomics and metabolomics

The conventional pipeline for biomarker development involves a discovery phase, typically conducted by mass spectrometry (MS), followed by validation and clinical application, usually on an alternative platform, such as immunoassay. Whilst this approach is suitable for the development of single biomarkers, with the current drive towards larger panels of multiplexed biomarkers, the process becomes inefficient and costly. Consequently, the emphasis is now shifting towards performing full biomarker discovery, qualification and quantification on the same technology platform. The ease of multiplexing and ability to determine protein modifications makes MS an attractive alternative to antibody-based technologies. In addition, developments in quantitative MS, through the application of stable isotope labelling and scanning techniques, such as multiple reaction monitoring (MRM), have greatly enhanced both the specificity and sensitivity of MS-based assays to the point that they can rival immunoassay for some analytes. This review focuses on the application of MRM for quantitative MS analysis, particularly with respect to proteins and peptides.