Serum Mass Spectrometry Assay for Minimal Residual Disease Detection
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Solution Overview
Problem
Current methods for monitoring M-protein in multiple myeloma are limited by the need for invasive bone marrow sampling, low sensitivity, and inability to detect minimal residual disease (MRD) at submicroscopic levels, particularly in archived patient samples.
Innovation Solution
A fully serum-based mass spectrometry (MS) assay using de novo sequencing to quantify M-protein directly from serum samples, eliminating the need for bone marrow sampling and enabling detection of M-protein in archived protein electrophoresis gels, thereby allowing for sensitive monitoring of MRD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If serum protein electrophoresis (SPE) is used to detect M-protein, then the method is simple and widely available, but the sensitivity is insufficient (cannot detect levels lower than 0.5 g/L)
Solution Approach 1:
The patent replaces the mechanical/electrical separation system of SPE with a mass spectrometry-based detection system. The MS assay measures mass-to-charge ratios of M-protein peptides, enabling detection at picogram levels (100-1000 times more sensitive than SPE) while avoiding the sensitivity limitations of electrophoretic separation.
Solution Approach 2:
The patent introduces proteotypic peptides as intermediary markers for M-protein detection. Instead of directly detecting intact M-protein, the assay detects specific peptide fragments derived from M-protein through enzymatic digestion, which are then quantified by mass spectrometry. This intermediary approach enables highly sensitive and specific detection.
2Measurement precision
If bone marrow sampling is performed to obtain M-protein sequence information, then molecular techniques can identify patient-specific M-protein, but the procedure is invasive and carries sampling error risk
Solution Approach 1:
The patent enables the serum sample to self-reveal M-protein sequence information through de novo sequencing by mass spectrometry. The MS system analyzes peptide mass spectra to deduce amino acid sequences directly from the serum-derived M-protein, eliminating the need for external bone marrow sampling while maintaining patient-specific accuracy.
Solution Approach 2:
Instead of obtaining M-protein sequence information from bone marrow and then applying it to serum detection, the patent inverts the approach by directly sequencing M-protein from serum samples using de novo MS sequencing. This reversal eliminates the invasive bone marrow procedure while achieving the same sequence identification goal.
3Reliability
If prospective cohort studies are conducted to determine treatment effects, then comprehensive data can be collected, but the process takes years to complete
Solution Approach 1:
The patent applies the MS assay to archived serum samples that were previously collected during clinical studies. By retrospectively analyzing existing samples with the highly sensitive MS method, the study can determine treatment effects and disease progression without requiring new prospective cohort enrollment, thereby dramatically reducing study duration while maintaining data reliability.
4Measurement precision
If conventional SPE-based diagnostics are used, then current M-protein levels can be detected, but minimal residual disease at submicroscopic levels cannot be identified
Solution Approach 1:
The patent replaces the macroscopic electrophoretic separation of SPE with mass spectrometric detection, which operates at the molecular level. The MS system can detect and quantify picogram amounts of M-protein peptides, enabling identification of minimal residual disease that is far below the detection threshold of conventional SPE methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides earlier detection of disease progression by an average of 340 days compared to conventional techniques, enabling more frequent monitoring and improved assessment of treatment efficacy and relapse detection.
Implementation Method 1
quantifying a M-protein in a sample by mass spectrometry (MS)
Implementation Method 2
performing an enzymatic digestion on proteins present in said gel part or on a protein extract thereof in order to provide a peptide digest
Implementation Method 3
separating a M-protein from other immunoglobulins or free light chains in a sample by electrophoresis in a gel
Data Source
AI summary
The present invention provides a method for quantifying a monoclonal (M-) protein in a sample of a subject, the method comprising the steps of:—subjecting a serum sample of a subject to serum protein electrophoresis (SPE) in a gel, preferably serum protein electrophoresis in an agarose gel, to separate serum proteins into different serum protein fractions, optionally followed by immunofixation electrophoresis (IFE) and further optionally involving immunostaining of the gel;—excising from said gel a gel part comprising, or suspected of comprising, a M-protein;—performing an enzymatic digestion of proteins present in said gel part in order to provide a peptide digest comprising at least one M-protein peptide;—subjecting said peptide digest comprising said at least one M-protein peptide to liquid chromatography-mass spectrometry (LC-MS) to determine a quantity of said at least one M-protein peptide, thereby quantifying said M-protein in said sample.