Drop-Off ddPCR Assay for Sensitive ESR1 Hotspot Mutation Detection
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Solution Overview
Problem
Current methods for detecting ESR1 mutations in breast cancer are complex, costly, and limited in sensitivity, often missing less frequent mutations associated with endocrine therapy resistance, and require invasive serial biopsies for monitoring.
Innovation Solution
A drop-off digital PCR (ddPCR) assay using a single hydrolysis probe for detecting ESR1 hotspot mutations at codons 380, 536, and 538, combined with a reference probe, allows for sensitive and specific identification and characterization of multiple mutations in a single reaction, reducing sample and cost requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current methods for detecting ESR1 mutations are used, then detection can be performed, but the methods are complex and costly
Solution Approach 1:
The patent divides the detection process into two distinct phases: enrichment (using COLD-PCR to selectively amplify mutant alleles) and detection (using ddPCR with mutation-specific probes). This segmentation allows each phase to be optimized independently, reducing overall complexity while maintaining high reliability in detecting rare ESR1 mutations amidst wild-type background.
Solution Approach 2:
The patent introduces COLD-PCR enrichment as an intermediary step between sample preparation and final detection. This intermediary process selectively amplifies mutant alleles before the ddPCR detection phase, enabling reliable detection of low-frequency mutations without requiring direct complex analysis of the entire DNA sample.
2Reliability
If current methods are used to detect all ESR1 mutations, then comprehensive detection is achieved, but sensitivity is limited and less frequent mutations are missed
Solution Approach 1:
The patent changes the thermal parameters during PCR amplification by implementing a cold denaturation step (COLD-PCR) where the denaturation temperature is lowered below the melting temperature of wild-type probe-target hybrids. This parameter change selectively enriches mutant alleles that have lower melting temperatures, dramatically improving analytical sensitivity for detecting rare mutations including less frequent variants.
Solution Approach 2:
The patent replaces conventional PCR amplification mechanics with COLD-PCR selective enrichment mechanics. Instead of uniformly amplifying all DNA sequences, the system uses temperature-controlled selective amplification that physically distinguishes and enriches mutant alleles based on their thermal stability differences, enabling detection of mutations at very low frequencies.
3Reliability
If serial biopsies are performed for monitoring, then treatment response can be tracked, but the procedure is invasive
Solution Approach 1:
The patent uses circulating tumor DNA (ctDNA) in blood plasma as a non-invasive copy or surrogate of the tumor genome. Instead of repeatedly performing invasive tissue biopsies, the system analyzes DNA released by tumor cells into the circulation, providing the same monitoring information about ESR1 mutation status and treatment response through simple blood draws.
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 achieves high sensitivity in detecting up to 95% of activating ESR1 mutations, including polyclonal mutations, with improved analytical sensitivity for monitoring treatment response and predicting resistance, enabling early treatment adaptation and reducing the risk of metastasis.
Implementation Method 1
an oligonucleotide reference (REF) hydrolysis probe, labeled with a fluorophore
Implementation Method 2
oligonucleotide hotspot (HOTSPOT) hydrolysis probe
Implementation Method 3
a drop-off digital polymerase chain reaction (PCR)
Data Source
AI summary
The present invention relates to an in vitro method for identifying and/or characterizing one or more mutations in a hotspot mutation sequence of at least one ESR1 target fragment from a DNA sample, with a drop-off digital polymerase chain reaction (PCR).