CHAPTER 14:MRM-based Protein Quantification with Labeled Standards for Biomarker Discovery, Verification, and Validation in Human Plasma

Multiple reaction monitoring (also called selected reaction monitoring) is a targeted technique and has been proposed and used for the verification of biomarkers, which have been “discovered” by means of a different technique. This biomarker discovery step has usually been based on some type of differential expression analysis—either mass spectrometry-based or an alternative technique, such as 2-D gels—that produces results in terms of “fold changes”. MRM analysis, which can provide results in terms of protein concentration, holds great promise for the high-throughput verification and validation of candidate biomarkers in human biofluids, such as blood plasma. In addition, because MRM assays are able to include increasingly complex panels of proteins in a single assay (multiplexing), they can also be used as biomarker discovery tools, enabling the simultaneous screening of large numbers of proteins for a variety of diseases, including non-communicable diseases, such as cardiovascular disease and cancer. This enables the discovery of biomarker panels, comprised of several proteins, which often have higher diagnostic accuracies than can be obtained through the use of single proteins as biomarkers. Based on screening results, MRM-based assays for smaller sets of potential biomarkers can then be developed in order to validate these biomarker panels on large numbers of patient samples.