Protein Biomarker Quantification by Immunoaffinity Liquid Chromatography–Tandem Mass Spectrometry: Current State and Future Vision

Abstract

Immunoaffinity–mass spectrometry (IA-MS) is an emerging analytical genre with several advantages for profiling and determination of protein biomarkers. Because IA-MS combines affinity capture, analogous to ligand binding assays (LBAs), with mass spectrometry (MS) detection, this platform is often described using the term hybrid methods. The purpose of this report is to provide an overview of the principles of IA-MS and to demonstrate, through application, the unique power and potential of this technology. By combining target immunoaffinity enrichment with the use of stable isotope-labeled internal standards and MS detection, IA-MS achieves high sensitivity while providing unparalleled specificity for the quantification of protein biomarkers in fluids and tissues. In recent years, significant uptake of IA-MS has occurred in the pharmaceutical industry, particularly in the early stages of clinical development, enabling biomarker measurement previously considered unattainable. By comparison, IA-MS adoption by CLIA laboratories has occurred more slowly. Current barriers to IA-MS use and opportunities for expanded adoption are discussed. The path forward involves identifying applications for which IA-MS is the best option compared with LBA or MS technologies alone. IA-MS will continue to benefit from advances in reagent generation, more sensitive and higher throughput MS technologies, and continued growth in use by the broader analytical community. Collectively, the pursuit of these opportunities will secure expanded long-term use of IA-MS for clinical applications.

Construction and Validation of a Protein Prognostic Model for Lung Squamous Cell Carcinoma

“…Several studies have suggested prognostic factors for LUSCC, including proteins, mRNAs, lncRNAs and miRNAs. Tumor protein biomarkers demonstrated important roles in cancer detection, clinical outcome prediction or effective therapy selection [7][8][9]. Of note, protein biomarkers are…”

Immunoaffinity microflow liquid chromatography/tandem mass spectrometry for the quantitation of PD1 and PD‐L1 in human tumor tissues

“…Immunoaffinity LC/MS/MS is an emerging analytical platform in the analysis of protein biomarker studies as it combines the advantage of immuno‐capture to enrich analyte quantities with high specificity of detection of multiple surrogate peptides 22 . This study describes several key elements that are needed for the accurate determination of PD1 and PD‐L1 levels in human tumor tissues by IA‐LC/MS.…”

A Two-Dimensional Affinity Capture and Separation Mini-Platform for the Isolation, Enrichment, and Quantification of Biomarkers and Its Potential Use for Liquid Biopsy

“…Used separately, they can generate variations in the results they produce [ 32 ]. Conversely, the merging of solid-phase extraction (SPE)/affinity-capture with chromatographic or electrophoretic methods, allows for isolation, concentration, separation, detection, quantification, and characterization of individual target biomarkers and/or structurally related analytes [ 25 , 33 , 34 ]. Moreover, coupling on-line solid-phase extraction methods to HPLC or CE instruments have been shown to provide many advantages, including speed of analysis and reproducibility of results, particularly, when antibodies, aptamers, and/or lectins have been used for the isolation and concentration of target analytes.…”

“…The superior resolution power of CE permits the separation of closely structurally related analytes. Significant improvements in the analysis of biomarkers can also be achieved when powerful detectors, such as laser-induced fluorescence detection and/or mass spectrometry, are used for their detection and characterization [ 25 , 34 ].…”