Digital Droplet PCR Assay for AR Variant Detection
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Solution Overview
Problem
Prostate cancer drug resistance is primarily due to the expression of androgen receptor (AR) splice variants, which confers resistance to current therapies, including enzalutamide, abiraterone, and taxanes.
Innovation Solution
A method involving the capture of circulating cancer cells, extraction of mRNA, and detection and quantification of full-length androgen receptor (AR-FL), AR-V7, and AR-V567 using parallel digital droplet PCR assays, allowing for precise identification and monitoring of AR variants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR methods are used to detect AR variants, then the detection process is simpler, but the sensitivity and specificity are insufficient to distinguish between similar variants like AR-V7 and AR-V9
Solution Approach 1:
The patent divides the detection process into separate parallel assays for different AR variants (AR-FL, AR-V7, AR-V9) using distinct primer sets. Each variant is detected in an independent reaction, allowing high specificity while maintaining manageable complexity through modular assay design.
Solution Approach 2:
The patent employs digital droplet PCR technology which changes the physical parameter of the reaction system by partitioning the sample into thousands of individual droplets. This parameter change enables absolute quantification and significantly improves detection precision for distinguishing between similar AR variants.
2Quantity of substance
If mRNA is extracted from limited clinical samples, then the sample requirement is reduced, but the detection sensitivity must be sufficiently high to detect low abundance transcripts
Solution Approach 1:
The patent replaces conventional mechanical amplification methods with digital droplet PCR, which uses stochastic partitioning and fluorescence detection to achieve high sensitivity. This substitution allows detection of low abundance AR variant transcripts from minimal clinical samples with precise quantification.
Solution Approach 2:
The patent adds a spatial dimension to the detection system by partitioning the reaction into thousands of individual droplets in three-dimensional space. This dimensional change enables simultaneous detection of multiple targets with high sensitivity while requiring minimal input material.
3Adaptability or versatility
If multiple AR variants are detected simultaneously, then comprehensive diagnostic information is obtained, but the assay complexity increases
Solution Approach 1:
The patent creates a universal digital droplet PCR platform that can detect multiple AR variants (AR-FL, AR-V7, AR-V9) simultaneously using distinct primer sets in parallel reactions. This multi-functional approach provides comprehensive diagnostic information while the standardized ddPCR methodology keeps the overall system complexity manageable.
Data Source
Figure 1A~1B
Figure 1C-1
Figure 1C-2
AI summary
Sensitive assay methods are described herein that involve (a) capturing circulating cancer cells (e.g., by any method); (b) extracting mRNA and (c) detecting and quantifying each of full-length androgen receptor (AR-FL), androgen receptor variant 7 (AR-V7), and androgen receptor variant 5,6,7 (AR-V567) in parallel digital droplet PCR assays. Additional methods are described herein for detecting and/or isolating circulating cancer cells by selecting for cells that express transferrin receptor.