Cell-Free DNA Monitoring via Mutually Exclusive Mutation Controls
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Solution Overview
Problem
Current cancer therapies face limitations due to the inability to accurately monitor molecular changes in tumors over time, particularly in cancers like EGFR mutant lung cancer and BRAF mutant melanoma, where drug resistance develops, and existing blood-based assays lack sensitivity and specificity for detecting tumor DNA markers.
Innovation Solution
A method involving the isolation and measurement of cell-free nucleic acids from plasma samples, using a quality control step with housekeeping genes and a 'gold standard' control population to differentiate between tumor-specific mutations and assay artifacts, enabling non-invasive monitoring of cancer progression and treatment efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sensitivity assays are used to detect low concentrations of tumor DNA in blood, then detection sensitivity is improved, but false positives increase and specificity deteriorates
Solution Approach 1:
The patent introduces cell-free DNA as an intermediary substance that mediates between the tumor and the detection assay. By detecting tumor-derived cell-free DNA in plasma rather than directly detecting tumor cells or using invasive biopsies, the assay achieves high sensitivity while maintaining specificity through the use of tumor-specific genetic markers in the cell-free DNA population
Solution Approach 2:
The patent changes the detection parameter from detecting intact tumor cells or tissue to detecting fragmented cell-free DNA molecules in plasma. This parameter change enables non-invasive sampling while maintaining the ability to detect tumor-specific mutations, thereby improving both sensitivity and specificity simultaneously
2Measurement precision
If conventional tumor genotyping is performed, then mutation detection is achieved, but false negatives occur and inability to perform repeat biopsies prevents monitoring
Solution Approach 1:
The patent creates a liquid copy of the tumor's genetic information in the form of cell-free DNA circulating in plasma. This copy can be obtained repeatedly through simple blood draws, eliminating the need for invasive repeat biopsies while maintaining accurate mutation detection capability for monitoring treatment response and resistance development
Solution Approach 2:
The patent performs preliminary genotyping of the tumor to identify specific mutations, then uses these identified mutations as targets for subsequent monitoring of cell-free DNA in plasma. This preliminary action establishes a baseline that enables sensitive and specific tracking of tumor burden and treatment response over time
3Ease of operation
If blood-based assays are used for non-invasive monitoring, then ease of operation is improved, but detection sensitivity deteriorates due to low concentrations of tumor DNA
Solution Approach 1:
The patent applies local quality by focusing the detection assay on tumor-specific genetic markers within the cell-free DNA population rather than attempting to detect all DNA equally. By designing assays that target specific mutations or tumor-associated genetic features, the method achieves high sensitivity for tumor DNA detection despite its low concentration in the overall plasma DNA pool
Data Source
AI summary
The invention provides methods to monitor cell free nucleic acids. The method comprises obtaining a plasma sample from a subject known to have a cancer characterized by a pair of mutually exclusive mutations specific to the cancer; isolating cell free nucleic acids from the plasma sample obtained from the subject; measuring the amount a housekeeping gene and/or total DNA in the cell free nucleic acids isolated from the plasma sample to confirm that the amount of housekeeping gene and/or total DNA in the sample is within a selected range; measuring the amount of a first of the pair of mutually exclusive mutations specific to the cancer in the cell free nucleic acids isolated from the plasma sample; and indicating in a report that the subject has the first mutation when (a) the amount of the housekeeping gene and/or total DNA in the cell free nucleic acids isolated from the plasma sample is within the selected range and (b) the amount of the first mutation is increased as compared to a control amount, wherein the control amount is determined by measuring the apparent amount of the first mutation in control cell free nucleic acids isolated from plasma samples obtained from control subjects known to have the second of the pair of mutually exclusive mutations specific to the cancer using measuring conditions substantially the same as those used to measure the amount of the first mutation in the cell free nucleic acids isolated from the plasma sample from the subject.